Research Marc De Broe

Abstract

In the last 30 years, a worldwide increase in chronic kidney disease was reported in agricultural regions and hence was named Chronic Interstitial Nephritis in Agricultural Communities (CINAC). The exact cause and molecular disease mechanism underlying CINAC remain unknown. However, increasing evidence points towards exposure to agrochemicals (e.g. pesticides) as a causal factor. Recently, in kidney biopsies from CINAC-patients, we discovered a lysosomal lesion in proximal tubular cells (PTCs). Moreover, we discovered the same lesion in transplant patients treated with nephrotoxic immunosuppressive calcineurin inhibitors (CNIs), leading to the paradigm that CINAC indeed is caused by a toxin. Yet, the nature of the toxin, as well as cell biological mechanisms involved remain elusive. Therefore, we will focus our investigation on human renal biopsies of CINAC- and transplant-patients, who will be subjected to single nucleus RNA sequencing to generate a molecular profile of the renal cells. With this information, we will conduct reverse toxicogenomics to identify possible causal toxins. Next, gene expression analysis, complemented with functional analyses in primary human renal cell cultures as well as in rodents, allows an extensive mechanistic investigation supplementing our in silico analyses. Finally, molecular markers obtained from these efforts will be visualized in human samples in their histopathological context to link our molecular findings translational diagnosis.

Researcher(s)

• Promoter: Vervaet Benjamin
• Co-promoter: De Broe Marc
• Fellow: da Silva Fernandes Sylvina

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Farmers rely on Plant Protection Products (PPPs) to maximise their yields. However, some PPPs are potentially harmful to environmental, plant, animal and human health. Data on the risks and impacts associated with PPPs' is, at present, scarces and fragmented. There is a need to deliver an integrated approach to fill this research gap. SPRINT is built around 4 objectives: 1) Develop, test, validate and deliver a Global Health Risk Assessment Toolbox for the integrated assessment of the impacts of pesticides on terrestrial and aquatic ecosystems as well as on plant, animal and human health. Three main attributes for health status will be examined: resilience, reproduction/productivity and manifestation of diseases. The goal is integrated risk assessment at the local, regional, national and European level, focusing on different PPP use patterns and detected residue mixtures in contrasting farming systems (conventional, integrated, organic). 2) Harmonise data collection approaches across Europe and collect the critical data needed to inform integrated approaches to fully assess overall risks and impacts of pesticide formulations, residues and metabolites. 3) Assess the environmental and economic sustainability of alternative strategies to pesticide use. 4) Develop transition pathways towards more sustainable plant protection in a multi-actor approach SPRINT is based on a multi-actor approach to engage stakeholders and identify needs, improving farmer and citizen awareness, joint development of novel strategies for reduced reliance on PPP use, and creation of an enabling environment for adoption and change. SPRINT consists of 9 interlinked work packages. The distribution and the impacts of PPP on environmental, plant, animal and human health will be evaluated at 11 case study sites (CSS), ten located in diverse agricultural European landscapes, and one in Argentina (soy production for feed for EU market). SPRINT's encompasses a multidisciplinary approach: PPP environmental pathways, and direct (food/feed ingestion) and indirect (air/dust inhalation and dermal uptake) animal and human exposure routes will be assessed to improve current fate, exposure, and toxicokinetic models (e.g. EFSA-FOCUS, BROWSE, BREAM). (Eco)toxicological assays will be performed based on CCS findings, using existing and improved procedures, including alternative testing criteria and new target organisms. Such assays will cover direct and indirect exposure to multiple PPP residues, realistic ranges of PPP concentrations, multi-species scenarios, and short- and long-term time horizons. Modelling of sustainability and cost-benefit analysis at the farm and macroeconomic level will be conducted to derive recommendations for sustainable transition pathways, and a research agenda on PPPs.

Researcher(s)

• Promoter: Vervaet Benjamin
• Co-promoter: De Broe Marc
• Co-promoter: D'Haese Patrick

Research team(s)

• Pathophysiology

Project website

Project type(s)

• Research Project

Abstract

This multi-centre, practice-oriented, repurposing, double-blind, placebo-controlled, randomized clinical trial evaluates the effect of metformin treatment on the progression of chronic renal failure

Researcher(s)

• Promoter: D'Haese Patrick
• Promoter: Vanden Berghe Tom
• Co-promoter: De Broe Marc
• Co-promoter: D'Haese Patrick

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Chronische nierinsufficiëntie (CKD) is een klinische conditie gekenmerkt door the progressief verlies van functionele renale massa. Gedurende de laatste 20 jaar werd in een aantal agrarische gemeenschappen een continue stijging van patiënten met chronische nierinsufficiëntie waargenomen, die wereldwijd miljoenen menen treft. De ziekte werd Chronische Interstitiële Nefritis in Agrarische Culturen genoemd (CINAC). Daar waar chronische dehydratie door sommigen als de voornaamste oorzaak van de aandoening werd voorgesteld, is er momenteel meer en meer evidentie voor blootstelling aan agrochemicaliën als belangrijkste oorzaak. De oorzakelijke oorzaak en onderliggende mechanismen blijven echter nog steeds een onderwerp van discussie.

Researcher(s)

• Promoter: D'Haese Patrick
• Co-promoter: De Broe Marc
• Co-promoter: Vervaet Benjamin

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Goals of the project: 1. To investigate the bio-physicochemical mechanism of crystal clearance and the role of pH and inflammation therein. 2. To study the fundamental effects of acute hyperphosphatemia induced by therapeutic oral sodium phosphateintake on (i) the systemic regulators of the phosphate balance, (ii) the tubular epithelial phenotype and (iii) renal function, and investigate if these effects can be eliminated by limiting or inhibiting phosphate absorption in the intestine.

Researcher(s)

• Promoter: D'Haese Patrick
• Co-promoter: De Broe Marc
• Co-promoter: Verhulst Anja

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Promoter: D'Haese Patrick

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Co-promoter: D'Haese Patrick
• Fellow: Neven Ellen

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Promoter: D'Haese Patrick
• Fellow: Persy Veerle

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Promoter: D'Haese Patrick
• Co-promoter: Bosmans Jean-Louis
• Fellow: Spaepen Gie

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Retention of crystals in renal tubuli leads to the formation of kidney stones. Multiple factors have been correlated with this initial phase of nephrolithiasis: renal injury/-regeneration, upregulation of osteopontin (OPN) and hyaluronan (HA) - known crystal binding molecules - and redistribution of their common receptor CD44. In this study we will try to elucidate the role of renal injury, OPN and HA in crystal retention by using animal models of nephrolithiasis on one hand and OPN knock-out mice, where both in vivo and in vitro experiments will be performed, on the other.

Researcher(s)

• Promoter: De Broe Marc
• Co-promoter: D'Haese Patrick
• Fellow: Vervaet Benjamin

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

All current immunosuppressive treatments in transplantation medicine use calcineurin inhibitors (CI's) in particular cyclosporin and/or tacrolimus. Chronic allograft nephropathy (CAN) limits the long term survival of transplanted kidneys. It is already proven that treatment with CI's plays a roll in the development CAN but the precise contribution of CI's in this pathology is still not known. New non-nephrotoxic immunosuppressive agents, eg Sirolimus, offer interesting perspectives. In this study we'll analyse human kidney biopsies coming from a randomized multicentric study where patients are treated with cyclosporin or Sirolimus.. Fine needle biopsies are taken before implantation and after 6 months. We want to investigate the process of cellular infiltration, inflammation and fibrosis in the transplanted kidney using molecular and immunohistochemic techniques.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Spaepen Gie

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

In a prospective, randomized study in de novo kidney transplant recipients, we will compare the influence of a combination therapy with prednisolone, mycophenolate mofetil, and cyclosporine with a combination therapy with prednisolone, mycophenolate mofetil, and rapamycine, on the expression of genes, associated with inflammation and fibrosis in protocol biopsies of the graft, six months after transplantation. Glomeruli, tubulo-epithelial cells and interstitial cells will be isolated by means of the laser capture microscope. After RNA-extraction, we will perform semiquantitative RT amplification with Taqman PCR for the genes of interest: i.e. IL 10, IL 12, TNF alpha, B7-1, B7-RP1, CD40, CXCR3, CCR5, perforine, granzyme, angiotensine II, TGF-ß1, PAI-1, TIMP-1, and endotheline.

Researcher(s)

• Promoter: Bosmans Jean-Louis
• Co-promoter: Bogers John-Paul
• Co-promoter: De Broe Marc
• Co-promoter: Van Rompay An
• Co-promoter: Verpooten Gert
• Co-promoter: Ysebaert Dirk

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Persy Veerle

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: D'Haese Patrick
• Co-promoter: De Broe Marc

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Esmans Edgard
• Co-promoter: De Broe Marc
• Co-promoter: De Coen Wim
• Co-promoter: Moens Luc
• Co-promoter: Van Onckelen Harry

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Co-promoter: Bosmans Jean-Louis
• Co-promoter: Van Marck Eric
• Co-promoter: Van Rompay An
• Co-promoter: Vermeulen Peter

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

Following previous findings in the Laboratory of Nephrology-Hypertension demonstrating both strontium and lanthanum to induce bone lesions in an experimental rat model with chronic renal failure, which histologically are expressed as osteomalacia, it will in the present research project be investigated wether the mineralization defect resulting from exposure to these elements, develops via an identical pathway. Therefore it will be assessed whether the disturbed mineralization is due to a pure physicochemical, extracellular process or on the other hand occurs via a direct effect on the osteoblast. Also will the interference of both elements with the secretion/synthesis of a series of relevant bone matrix proteins be investigated. To find an answer to these questions in vitro (primary osteoblast cultures) as well as in vivo (rat model with chronic renal failure) set-ups will be applied.

Researcher(s)

• Promoter: D'Haese Patrick
• Co-promoter: De Broe Marc
• Fellow: Bervoets An

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Acute renal failure was and continues to be a common renal disease with high incidence and mortality (50-60 %) and is mainly caused by an ischemia/reperfusion injury (IRI). Besides an acute ischemic toxic renal failure, a kidney transplant is always accompanied with a period of warm and cold IRI. This last form of ischemic injury can lead to a delayed graft function and might have a negative impact on long-term graft survival. Unfortunately, the mechanisms underlying this syndrome are still poorly understood. Therefore, limiting the morbidity and mortality of this syndrome will require more research trying to unravel the pathophysiological mechanism of these pathologies. We have explored the effects of renal IRI in the presence of chronic renal failure. In a first study rats underwent a renal mass reduction (remnant kidney model) to induce a stable chronic renal failure (Vercauteren SR, J. Am. Soc. Nephrol. 1999,10:2551-2561). In this model, after a 12-week stable chronic renal failure, an ischemic injury was introduced and the rats were sacrificed after 0-1-3-6-10-15-21 and 35 days. The animals with chronic renal failure were partially protected against IRI. In a second study we explored the influence of chronic renal failure on acute renal failure with a transplantation experiment. Inbred male rats were used in order to avoid rejection as a confounding factor. In normal Lewis rats (normal renal function, NRF) and in remnant kidney rats (chronic renal failure, CRF) a normal kidney was transplanted after 60 minutes of ischemia and the rats were sacrificed at day 1-3 and 10. Filtration capacity of the isografts in CRF rats was preserved to approximately ' of its normal capacity on the 1st day post-transplantation, whereas it fell to 0 in NRF rats. This was reflected by a significantly higher increase in serum creatinine in the latter group. The isografts in CRF rats had a significantly lower degree of acute tubular necrosis and no increase in number of macrophages and T lymphocytes in the first 24 hours in contrast to NRF rats. Epithelial regeneration and repair started earlier in the CRF group. In conclusion, the present study indicated that chronic uremia blunts ischemia/reperfusion injury of a transplanted kidney, and that its regeneration capacity was certainly not hampered by the presence of chronic uremia. These results are currently the basis for a third study on modulation of early leukocyte-endothelial interactions due to immunological disturbances inherent to the uremic environment. All the obtained results suggest that chronic renal failure has an influence on the expression of adhesion molecules, endothelins and costimulatory molecules on the endothelial cells. In addition, the biochemical status associated with renal failure can induce a switch in T cells and macrophages to an anti-inflammatory phenotype. In this third study the transplanted rats have been sacrificed at 2 and 6 hours reperfusion. Evaluation of the kidney injury is performed by functional and morphological parameters and evaluation of the cellular infiltration is currently under progress. The RNA expression level of various adhesionmolecules like E-selectin, ICAM-1, endothelin-1, and costimulatory ligands like B7-1, B7-2 and possible other relevant molecules will be temporally compared by a semi-quantitative/real-time RT-PCR. The expression level and localization of ICAM-1, B7-1, B7-2, and other relevant molecules will be compared at the protein level using immunohistochemical stainings.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Van Rompay An

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

ARF still affects 5% of all hospitalized patients, a disease for which no specific therapy is available. ARF still carries a very high mortality rate of more than 50%. The mechanisms underlying this syndrome are still poorly understood. An ischemic insult of the kidney results in ARF, going along with tubular necro-sis of the S3-segment of the proximal tubular cells. This leukocyte infiltrate exists of mononuclear cells, i.e. monocytes/macrophages and helper-T cell. Accumu-lation of polymorphonuclear cells is absent after IRI. Evidence that these inflammatory cells play a role in renal IRI came from studies showing that antibodies against adhesion molecules such as ICAM-1 and an-tibodies against T-cell/antigen-presenting cell 'costimulatory pathway B7-CD28' (CTLA-4 Ig/anti-B7) resulted in a clear protection (functional and morphological). Stimulation of B7-1 results in a Th-1 cytokine profile whereas B7-2 results in a Th-2 profile. Which kind of acti-vated inflammatory cells, trapped in the vasa recta of the ischemic kidney, expressing CD28 needs further investigation. The ever-increasing proportion of marginal donors for kidney transplantation and the problems these en-tail got our research group interested in studying chronic renal failure and the effect of superposition of an acute ischemic insult on chronic renal failure. In remnant kidney model (in the rat), 5/6 nephrectomy in-duces a moderate chronic renal failure, accompanied histologically by tubulointerstitial injury and a leu-kocyte infiltrate rich in macrophages. We demonstrated that these chronic renal failure animals were par-tially protected, both functionally and morphologically, against an acute ischemic insult to the kidney. It is as yet unknown which factors are responsible for this absence of increase in leukocyte infiltration in chronic renal failure animals after acute I/R injury. We showed a dramatic upregulation of this protein after acute IRI, with OPN being expressed in perinuclear, vesicular structures in proximal tubules and at the apical cell side in distal tubules. We have recently confirmed this role in OPN knockout mice: after I/R these animals showed significantly less macrophage infiltration in comparison with nor-mal mice.

Researcher(s)

• Promoter: De Broe Marc
• Promoter: D'Haese Patrick

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Proteomics is the large-scale analysis of total protein-expression in cells or tissues. Proteome studies include areas such (1) protein expression; (2) the regulation of protein activity; (3) protein interactions and complex formation; (4) protein trafficking and sequestration in subcellular compartments; (5) signaling and metabolic pathways (6) protein function; (7) characterization of post-translational modifications; (8) structural analysis; (9) drug mode-of-action; and (10) toxicity studies.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Ysebaert Dirk

Research team(s)

• Laboratory Experimental Medicine and Pediatrics (LEMP)

Project type(s)

• Research Project

Abstract

Acute renal failure (ARF) is a common renal disease, characterized by a rapid decline in renal function over a period of hours to days, resulting in the failure to excrete nitrogenous waste products and to maintain fluid electrolyte homeostasis. Although the care of injured patients has improved, ARF causes a very high mortality rate of more than 50%. A manifest and intriguing effect during acute tubular necrosis (ATN) is the prompt adherence/infiltration of inflammatory cells, immediately following injury, and their disappearance when the regeneration is complete. Evidence for a critical role for these inflammatory cells (T-cells) in ARF comes from blocking one of the costimulatory pathways necessary for T-cell activation. Indeed, blocking the B7-CD28 costimulation pathway with CTLA4-Ig ameliorated renal dysfunction and prevented cellular adherence/infiltration. We previously reported on the early expression and the critical localization of B7-1 molecule at the level of the endothelial cells of the ascending vasa recta in the rat using indirect methods. Since from the literature it appeared that B7 molecules could be directly visualized in the mouse (heart endothelial cells), we will set up an ischemia/reperfusion (I/R) mouse model to investigate the expression of B7 proteins in the endothelial cells of the ascending vasa recta. Serum creatinine will be used as a biochemical marker for renal function. Histological evaluation of renal injury and cell proliferation will be determined with PAS and PCNA staining. Immunohistochemical staining of B7-1 and B7-2 will be used to demonstrate the presence of these proteins on the endothelial cells of the ascending vasa recta in the mouse. Since the endothelial expression of B7 proteins seem to be very fast, we will investigate whether B7-1 and/or B7-2 are enriched on internal vesicles of Major Histocompatibility Complex (MHC) class II-enriched compartments or on exosomes in the endothelium. Previous studies showed that cultured endothelial cells could express MHCII proteins in hypoxic conditions. Immunohistochemical staining of the endothelial markers endothelin, MHCII proteins and CD40/CD40L will be used in the study of the activation of the endothelium of the vasa recta after acute ischemia/reperfusion injury (IRI). Our research group identified the early expression and the critical localization of the B7-1 molecule at the level of the endothelial cells of the vasa recta. T-lymphocytes and macrophages accumulated in the vasa recta very early after IRI through their binding of CD28 with B7-1. Anti-B7-1 treatment reduces the adhesion/infiltration of monocytes/macrophages and T-lymphocytes at the level of the vasa recta, and improved the blood flow to the outer medulla, resulting in a better-preserved kidney function. Identification and phenotyping of T-cells (CD4+/CD8+ and Th1/Th2) will be performed by antibody (CD4/CD8) and cytokine (IL2, IL4, IL10, IFN?) immunohistochemical staining. Differentiation between suppressive and proinflammatory macrophages, will be done by IL12 and IL10 staining. On tissue slides as well as on cells, isolated by laser capture microdissection in combination with real-time PCR (TaqMan assay), the determination of IL2, IL4, IL10, IL12 en IF? mRNA will be performed. The activation of CD4+ T-cells requires the binding of the T-cell receptor (TCR) to MHCII proteins. It is unknown whether the TCR/MHCII complex plays a role in T-cell mediated damage in acute IRI. Rat anti-mouse anti-Ia.19 will be used to block the TCR/MHCII binding and its possible effect on IRI will be evaluated. This study will contribute to a better view in the physiopathological mechanisms involved in acute renal failure after I/R, and in the long run may contribute to a decrease in morbidity and mortality.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: De Beuf Annelies

Research team(s)

Project type(s)

• Research Project

Abstract

In patients with chronic renal failure the interaction between the reduced renal function and increased exposure to a number of trace elements such as lanthanum, strontium and aluminum may result in the development of a mineralisation defect. In the frame of the present BOF project using both in vivo (chronic renal failure rat model) and in vitro (mineralizing osteoblast cultures) set ups we are aiming to assess whether the effe cts of the above mentioned trace elements (i) result from pure physicochemical, extracellul ar processes (ii) are mediated by the interference of these elements with a number of functional osteoblastic parameters (iii) are influenced by the degree of bone turnover (adynamic bone vs. hyperparathyroidism).

Researcher(s)

• Promoter: D'Haese Patrick
• Co-promoter: De Broe Marc

Research team(s)

• Pathophysiology

Project type(s)

• Research Project

Abstract

Osteopontin (OPN) is a glycosylated phosphoprotein, with a molecular structure that comprises several functional domains, including an RGD (arginine- glycine- aspartic acid) cell adhesion motif. In several experimental models of renal injury upregulated OPN expression was found during kidney damage and repair. However, the exact function of OPN in this setting remains unknown. In this research project we will investigate renal handling, molecular expression forms and subcellular localization of OPN in the kidney. We will investigate the function of OPN by blocking OPN expression in vivo by administration of neutralizing antibodies and antisense oligodeoxynucleotides on the one hand, and by studies in OPN knockout mice on the other. The effect of modified OPN expression on kidney damage and regeneration will be studied in models of ischemic and toxic acute tubular necrosis.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Persy Veerle

Research team(s)

Project type(s)

• Research Project

Abstract

Rationale: Until now dialysis osteomalacia (OM) has been associated with aluminum accumulation and vitamin D deficiency. This type of renal osteodystrophy is mainly characterized by a defective mineralisation and histologically expressed by an increased osteoid volume. Recently we noted increased bone strontium (Sr) concentrations in patients with OM as compared to patients presenting the other types of renal osteodystrophy. In an experimental study, using a chronic renal failure rat model, OM was induced which was accompanied by an increased calcium (Ca) excretion after oral administration of the element. By histochemical staining and X-ray microanalysis (EPXMA) we found the element to be localized in calcified bone and at areas surrounding the osteoid. Findings of an epidemiological study further indicated that within the dialysis population, patients from particular centers are at an increased risk for accumulation of the element. These observations are highly indicative for a causative role of Sr in the development of OM; in other words there is some evidence for the existence of a disease entity within the dialysis population of which nothing is known at he moment concerning the underlying physiopathological mechanisms. Aims and objectives: it will be investigated whether Sr (1) plays a direct role in the development of OM by direct interference with the mineralisation process (Ca-apatite formation, disturbance of the crystal lattice ...); (2) plays an indirect role in the development of OM by interfering with secretion/synthesis of the collagen and major non-collagenous matrix proteins (i.e. osteopontin (OPN), bone sialoprotein (BSP), osteocalcin (OC) and alkaline phosphatase (ALP)); (3) interferes with the biosynthesis of vitamin D at the level of the proximal tubule, (4) acts as an agonist of the Ca-sensing receptor in the thick ascending limb of the distal nefron causing hypercalciuria; (5) interferes with the mineralisation process via interaction with osteopontin as assessed in the OPN 'knock-out' mouse. Direct effect of Sr on the in vitro mineralisation: Using the already optimized mineralizing primary rat osteoblast cultures the direct effect of Sr, added in several doses to the culture medium, on the mineralisation will be studied. Quantification of the mineral deposition will be done by a computer-aided image analysis for nodule quantification. This will be correlated with the Ca-incorporation/efflux measured as the decrease/increment of Ca in the culture medium during the experiment. The incorporation of Sr and its interference with the crystal lattice will be investigated by EPXMA and histochemistry. Indirect effect of Sr on the in vitro mineralisation: (i) Using the same culture system as above, the possible interference of the element with the secretion of the major non-collagenous proteins will be studied. Here standard biochemical assays (ELISA, RIA, IRMA, ...) will be used to investigate the secretion of collagen propeptide, OPN, OC, ALP and BSP into culture medium samples taken at regular time intervals. (ii) To examine whether the effect of Sr on the mineralisation process is mediated by endocrine factors as PTH and vitamin D3 several doses of these hormones will be added to the medium in presence or absence of the element. (iii) Using suitable fluorochromes, the effect of Sr on the intracellular acid-base metabolism coupled to the intracellular Ca-concentration will be investigated.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verberckmoes Steven

Research team(s)

Project type(s)

• Research Project

Abstract

Rationale: Until now dialysis osteomalacia (OM) has been associated with aluminum accumulation and vitamin D deficiency. This type of renal osteodystrophy is mainly characterized by a defective mineralisation and histologically expressed by an increased osteoid volume. Recently we noted increased bone strontium (Sr) concentrations in patients with OM as compared to patients presenting the other types of renal osteodystrophy. In an experimental study, using a chronic renal failure rat model, OM was induced which was accompanied by an increased calcium (Ca) excretion after oral administration of the element. By histochemical staining and X-ray microanalysis (EPXMA) we found the element to be localized in calcified bone and at areas surrounding the osteoid. Findings of an epidemiological study further indicated that within the dialysis population, patients from particular centers are at an increased risk for accumulation of the element. These observations are highly indicative for a causative role of Sr in the development of OM; in other words there is some evidence for the existence of a disease entity within the dialysis population of which nothing is known at he moment concerning the underlying physiopathological mechanisms. Aims and objectives: it will be investigated whether Sr (1) plays a direct role in the development of OM by direct interference with the mineralisation process (Ca-apatite formation, disturbance of the crystal lattice ...); (2) plays an indirect role in the development of OM by interfering with secretion/synthesis of the collagen and major non-collagenous matrix proteins (i.e. osteopontin (OPN), bone sialoprotein (BSP), osteocalcin (OC) and alkaline phosphatase (ALP)); (3) interferes with the biosynthesis of vitamin D at the level of the proximal tubule, (4) acts as an agonist of the Ca-sensing receptor in the thick ascending limb of the distal nefron causing hypercalciuria; (5) interferes with the mineralisation process via interaction with osteopontin as assessed in the OPN 'knock-out' mouse. Direct effect of Sr on the in vitro mineralisation: Using the already optimized mineralizing primary rat osteoblast cultures the direct effect of Sr, added in several doses to the culture medium, on the mineralisation will be studied. Quantification of the mineral deposition will be done by a computer-aided image analysis for nodule quantification. This will be correlated with the Ca-incorporation/efflux measured as the decrease/increment of Ca in the culture medium during the experiment. The incorporation of Sr and its interference with the crystal lattice will be investigated by EPXMA and histochemistry. Indirect effect of Sr on the in vitro mineralisation: (i) Using the same culture system as above, the possible interference of the element with the secretion of the major non-collagenous proteins will be studied. Here standard biochemical assays (ELISA, RIA, IRMA, ...) will be used to investigate the secretion of collagen propeptide, OPN, OC, ALP and BSP into culture medium samples taken at regular time intervals. (ii) To examine whether the effect of Sr on the mineralisation process is mediated by endocrine factors as PTH and vitamin D3 several doses of these hormones will be added to the medium in presence or absence of the element. (iii) Using suitable fluorochromes, the effect of Sr on the intracellular acid-base metabolism coupled to the intracellular Ca-concentration will be investigated.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verberckmoes Steven

Research team(s)

Project type(s)

• Research Project

Abstract

Osteopontin (OPN) is a protein present in different tissues and organs including the kidney. In the kidney, the constitutive expression of this glycosylated phosphoprotein is confined to the apical cell surface in the lis of Henle and more distal parts of the nephron. After acute renal damage OPN is also present in perinuclear vesicles in proximal tubular cells. OPN function is unknown, but a role in tissue remodelling is suggested both by its molecular structure and upregulated expression during increased cell turnover in a variety of tissues. However, knowledge concerning its expression, metabolism and activity is insufficient to define the function of OPN in a precise and well-founded manner. Its renal biology has never been studied in cultures of human kidney cells. The general aim of this project is to gain a better insight in the function of renal OPN. Primary kidney cell cultures will allow the study of the heterogenic nephron cell population in both a mixed and separated manner. First, expression and metabolism of OPN will be studied, either or not after induction of cell damage, which can be considered as an in vitro analogue of acute renal failure. Next, blocking of OPN expression during further experiments may reveal some of its activities related to tissue remodelling. In a first part of this project primary kidney cell cultures will be established. Human mixed and separated (for example distal versus proximal) cultures have already been developed in our laboratory. Immunocytochemical identification and separation of cells is based on specific cell surface markers. Mixed cultures of rat and mice kidney cells will also be developed in view of the availability of OPN knockout mice and to allow the comparison with in vivo rat models of acute renal failure, respectively. The second part of this study will entail the development of detection methods for OPN expression and phosphorylation in cell culture. Both the mRNA level (Northern blotting, in situ hybridisation) and the protein level (immunocytochemistry, immunoblotting and ELISA) will be studied. During part three of this project OPN binding and possible internalisation by tubular cells will be studied by the addition of labeled OPN, either or not phosphorylated, to primary kidney cell cultures. In a fourth part it will be investigated whether induction of cell damage by hypoxia, lipopolysaccharide or HgCl2 results in a different expression and metabolization pattern of OPN. A number of parameters in relation to tissue remodelling will be examined (before and after cell damage) in kidney cell cultures from OPN knockout versus wild-type mice during the fifth part of this study. Parameters that will be examined are viability, growth, adhesion, differentiation, vimentin expression and inhibition of NO synthase (iNOS). Observed differences may be abrogated by adding recombinant or native bovine OPN to the cultures. In order to confirm the observations in knockout mice, OPN function will be studied during the sixth and last part of this study by the addition of oligodeoxynucleotides to the cell cultures before and after induction of cell damage. A dose-dependent effect may be observed. Moreover it will enable to perform measurements in the same system before and after blocking of OPN synthesis. The results of this research project may contribute to the development of diagnostic applications and the implementation of new therapeutic approaches of acute renal failure.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verhulst Anja

Research team(s)

Project type(s)

• Research Project

Abstract

Following previous findings in the Laboratory of Nephrology-Hypertension demonstrating both strontium and lanthanum to induce bone lesions in an experimental rat model with chronic renal failure, which histologically are expressed as osteomalacia, it will in the present research project be investigated wether the mineralization defect resulting from exposure to these elements, develops via an identical pathway. Therefore it will be assessed whether the disturbed mineralization is due to a pure physicochemical, extracellular process or on the other hand occurs via a direct effect on the osteoblast. Also will the interference of both elements with the secretion/synthesis of a series of relevant bone matrix proteins be investigated. To find an answer to these questions in vitro (primary osteoblast cultures) as well as in vivo (rat model with chronic renal failure) set-ups will be applied.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Bervoets An

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

The evaluation of the function or dysfunction of specific cells within a given organ requires in many cases the preceding viable isolation of these cells from a -sometimes- abundant amount of unwanted accessory cells. For this a number of cell separation techniques are available based on physical properties such as differences in cell density, cell adhesion, immunoaffinity etc' However, the flow cytometric cell sorting technique (based on electrostatic droplet formation) is the only separation technique that permits to separate different cell populations (up to 4) while simultaneously evaluating quite a number of properties such as size, internal complexity, DNA-content, presence or absence of up to 4 or 5 surface or cytoplasmic antigens. Since different cell populations may differ in subtle ways from others, this multiparametric flow cytometric sorting approach is in many cases a prerequisite to isolate the cells of interest: the primitive hematopoietic cell can only be defined by multiparametric labelling, kidney cell subpopulations, malignant versus normal cells, cell populations that are different in terms of cell cycle rate etc' It is clear that the availability of a cell sorter is a prerequisite for the four applying groups to study their respective cell(s) of interest. From 1990 onwards three of the four groups have built up expertise in the field, by joining forces and collaborating in the purchase of a FACStarPlus cell sorter. The output of numerous articles and several PhD theses may serve as proof of the good management of this interdisciplinary sorting facility. After 8 years of continuous heavy use, and in order to guarantee continuity in their research, the three initial groups, together with a fourth group (Tropical Medicine, Immunology) that meanwhile established close collaboration, now consider the purchase of a new generation cell sorter to be a priority. The growing number of users and applications have made the workload on the old instrument critically high. More elaborate simultaneous labelling and multiple and faster sorts are necessary to efficiently use the 'sometimes- scarce available starting material. This can only be accomplished by the new generation machines that guarantee much higher sort rates (up to > 30,000 cells/second, compared to 3000 cells/second on the old equipment) . Aerosol control systems implemented in the new machines offers prospects for work with potentially infectuous material (tropical medicine) The laser configuration of the old system is inadequate and the storage capacity and compatibility of the old computer system do not satisfy anymore the actual needs of a multi-user multidisciplinary facility. In what follows we will highlight the objectives and activities of the different research groups. It should be clear that no effort is made to link the respective topics: indeed the research topics described in this funding application are heterogeneous. Apart from some obvious common interests, the major link of these groups is the awareness that they all need cell sorting facilities to reach their goals.

Researcher(s)

• Promoter: Van Bockstaele Dirk
• Co-promoter: Berneman Zwi
• Co-promoter: De Broe Marc
• Co-promoter: D'Haese Patrick
• Co-promoter: Lardon Filip

Research team(s)

Project type(s)

• Research Project

Abstract

In the search for efficient, less toxic agents, lanthanum carbonate has been introduced as an alternative phosphate binder. Being a strong cationic, trivalent element lanthanum (La) has a very high affinity for phosphate. Physicochemically, the element shows a number of characteristics that are very similar to Ca and Al which in turn implies possible effects on bone. In a pilot study, using a chronic renal failure rat model, we recently were able to induce an osteomalacia (a type of renal osteodystrophy). In the frame of the present project we will investigate whether the effect of lanthanum on bone is also dose-dependent and occurs also at lower doses. Therefore, 5 groups of rats with normal renal function and 5 groups with chronic renal failure (8 anaimals per group) will be administered lanthanum by daily gavage of doses of respectively 0, 100, 500, 1000, 2000 mg/kg. After the loading period the animals will be sacrificed whereafter the bone will be examined histologically and histodynamically. During the loading period and at sacrifice blood and urine samples will also be taken for the determination of a number of relevant parameters.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

In clinical medicine, functional recovery of the kidney after acute renal failure due to ischemia is slower in order patients and patients with chronic renal failure. However, no experimental evidence exists whether or not chronic renal failure with its metabolic charges, has an influence on the regenerative capacity of the kidney after injury. Aftor renal injury, an inflammatory infiltrate of leukocytes develops in the renal interstitium, varying from one type of acute injury to another. The exact role of this influx of leucocytes is not fully clarified: besides having an injurious potential, the leukocytes could also enhance regeneration. The aim of the project is to examine the influence of chronic renal failure on the process of regeneration after ischemialreperfusion injury of the kidney in the rat, with special attention te the interstitial infiltrate of leukocyten.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Vercauteren Sven

Research team(s)

Project type(s)

• Research Project

Abstract

5-ASA (5-amino-salicylic acid) forms the main treatment in inflammatory bowel disease (IBD). Nephrotoxicity of 5-ASA therapy in IBD patients is recently described. The association is not clearly established since IBO itself can cause renal impairment. Therefore, all IBD patients seen at the outpatient clinic in 5 European countries (n=50 centres, n=2000 patients) will be registered and invited for a renal screening, aiming to determine incidence /prevalence of renal impairment in IBD patients and to investigate the association with 5-ASA therapy.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Osteopontin (OPN) is a glycosylated phosphoprotein, with a molecular structure that comprises several functional domains, including an RGD (arginine- glycine- aspartic acid) cell adhesion motif. In several experimental models of renal injury upregulated OPN expression was found during kidney damage and repair. However, the exact function of OPN in this setting remains unknown. In this research project we will investigate renal handling, molecular expression forms and subcellular localization of OPN in the kidney. We will investigate the function of OPN by blocking OPN expression in vivo by administration of neutralizing antibodies and antisense oligodeoxynucleotides on the one hand, and by studies in OPN knockout mice on the other. The effect of modified OPN expression on kidney damage and regeneration will be studied in models of ischemic and toxic acute tubular necrosis.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Persy Veerle

Research team(s)

Project type(s)

• Research Project

Abstract

Rationale: Until now dialysis osteomalacia (OM) has been associated with aluminum accumulation and vitamin D deficiency. This type of renal osteodystrophy is mainly characterized by a defective mineralisation and histologically expressed by an increased osteoid volume. Recently we noted increased bone strontium (Sr) concentrations in patients with OM as compared to patients presenting the other types of renal osteodystrophy. In an experimental study, using a chronic renal failure rat model, OM was induced which was accompanied by an increased calcium (Ca) excretion after oral administration of the element. By histochemical staining and X-ray microanalysis (EPXMA) we found the element to be localized in calcified bone and at areas surrounding the osteoid. Findings of an epidemiological study further indicated that within the dialysis population, patients from particular centers are at an increased risk for accumulation of the element. These observations are highly indicative for a causative role of Sr in the development of OM; in other words there is some evidence for the existence of a disease entity within the dialysis population of which nothing is known at he moment concerning the underlying physiopathological mechanisms. Aims and objectives: it will be investigated whether Sr (1) plays a direct role in the development of OM by direct interference with the mineralisation process (Ca-apatite formation, disturbance of the crystal lattice ...); (2) plays an indirect role in the development of OM by interfering with secretion/synthesis of the collagen and major non-collagenous matrix proteins (i.e. osteopontin (OPN), bone sialoprotein (BSP), osteocalcin (OC) and alkaline phosphatase (ALP)); (3) interferes with the biosynthesis of vitamin D at the level of the proximal tubule, (4) acts as an agonist of the Ca-sensing receptor in the thick ascending limb of the distal nefron causing hypercalciuria; (5) interferes with the mineralisation process via interaction with osteopontin as assessed in the OPN 'knock-out' mouse. Direct effect of Sr on the in vitro mineralisation: Using the already optimized mineralizing primary rat osteoblast cultures the direct effect of Sr, added in several doses to the culture medium, on the mineralisation will be studied. Quantification of the mineral deposition will be done by a computer-aided image analysis for nodule quantification. This will be correlated with the Ca-incorporation/efflux measured as the decrease/increment of Ca in the culture medium during the experiment. The incorporation of Sr and its interference with the crystal lattice will be investigated by EPXMA and histochemistry. Indirect effect of Sr on the in vitro mineralisation: (i) Using the same culture system as above, the possible interference of the element with the secretion of the major non-collagenous proteins will be studied. Here standard biochemical assays (ELISA, RIA, IRMA, ...) will be used to investigate the secretion of collagen propeptide, OPN, OC, ALP and BSP into culture medium samples taken at regular time intervals. (ii) To examine whether the effect of Sr on the mineralisation process is mediated by endocrine factors as PTH and vitamin D3 several doses of these hormones will be added to the medium in presence or absence of the element. (iii) Using suitable fluorochromes, the effect of Sr on the intracellular acid-base metabolism coupled to the intracellular Ca-concentration will be investigated.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verberckmoes Steven

Research team(s)

Project type(s)

• Research Project

Abstract

Osteopontin (OPN) is a protein present in different tissues and organs including the kidney. In the kidney, the constitutive expression of this glycosylated phosphoprotein is confined to the apical cell surface in the lis of Henle and more distal parts of the nephron. After acute renal damage OPN is also present in perinuclear vesicles in proximal tubular cells. OPN function is unknown, but a role in tissue remodelling is suggested both by its molecular structure and upregulated expression during increased cell turnover in a variety of tissues. However, knowledge concerning its expression, metabolism and activity is insufficient to define the function of OPN in a precise and well-founded manner. Its renal biology has never been studied in cultures of human kidney cells. The general aim of this project is to gain a better insight in the function of renal OPN. Primary kidney cell cultures will allow the study of the heterogenic nephron cell population in both a mixed and separated manner. First, expression and metabolism of OPN will be studied, either or not after induction of cell damage, which can be considered as an in vitro analogue of acute renal failure. Next, blocking of OPN expression during further experiments may reveal some of its activities related to tissue remodelling. In a first part of this project primary kidney cell cultures will be established. Human mixed and separated (for example distal versus proximal) cultures have already been developed in our laboratory. Immunocytochemical identification and separation of cells is based on specific cell surface markers. Mixed cultures of rat and mice kidney cells will also be developed in view of the availability of OPN knockout mice and to allow the comparison with in vivo rat models of acute renal failure, respectively. The second part of this study will entail the development of detection methods for OPN expression and phosphorylation in cell culture. Both the mRNA level (Northern blotting, in situ hybridisation) and the protein level (immunocytochemistry, immunoblotting and ELISA) will be studied. During part three of this project OPN binding and possible internalisation by tubular cells will be studied by the addition of labeled OPN, either or not phosphorylated, to primary kidney cell cultures. In a fourth part it will be investigated whether induction of cell damage by hypoxia, lipopolysaccharide or HgCl2 results in a different expression and metabolization pattern of OPN. A number of parameters in relation to tissue remodelling will be examined (before and after cell damage) in kidney cell cultures from OPN knockout versus wild-type mice during the fifth part of this study. Parameters that will be examined are viability, growth, adhesion, differentiation, vimentin expression and inhibition of NO synthase (iNOS). Observed differences may be abrogated by adding recombinant or native bovine OPN to the cultures. In order to confirm the observations in knockout mice, OPN function will be studied during the sixth and last part of this study by the addition of oligodeoxynucleotides to the cell cultures before and after induction of cell damage. A dose-dependent effect may be observed. Moreover it will enable to perform measurements in the same system before and after blocking of OPN synthesis. The results of this research project may contribute to the development of diagnostic applications and the implementation of new therapeutic approaches of acute renal failure.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verhulst Anja

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

This project aims at studying molecular and cellular events involved in tissue remodeling after injury. The following issues will be addressed : the activation of endothelial cells, recruitment of leukocytes and platelets, the effects of infiltrating and residents on the turn-over of the extracellular matrix and the pharmacological modulation of these processes.

Researcher(s)

• Promoter: Herman Arnold
• Co-promoter: Brutsaert Dirk
• Co-promoter: De Broe Marc
• Co-promoter: De Keulenaer Gilles

Research team(s)

• Physiopharmacology (PHYSPHAR)

Project type(s)

• Research Project

Abstract

In order to get a better insight in the mechanisms underlying the development of strontium-induced osteomalacia it will be looked for whether strontium either plays a direct (e.g. disturbance of the crystal cattice), or indirect role (e.g. interference with alkaline phosphatase and osteopontin at the level of the osteoblast, interference with 1-alfa hydroxylase at the level of the tubular cell).

Researcher(s)

• Promoter: De Broe Marc
• Co-promoter: D'Haese Patrick

Research team(s)

Project type(s)

• Research Project

Abstract

In clinical medicine, functional recovery of the kidney after acute renal failure due to ischemia is slower in order patients and patients with chronic renal failure. However, no experimental evidence exists whether or not chronic renal failure with its metabolic charges, has an influence on the regenerative capacity of the kidney after injury. Aftor renal injury, an inflammatory infiltrate of leukocytes develops in the renal interstitium, varying from one type of acute injury to another. The exact role of this influx of leucocytes is not fully clarified: besides having an injurious potential, the leukocytes could also enhance regeneration. The aim of the project is to examine the influence of chronic renal failure on the process of regeneration after ischemialreperfusion injury of the kidney in the rat, with special attention te the interstitial infiltrate of leukocyten.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Vercauteren Sven

Research team(s)

Project type(s)

• Research Project

Abstract

A histological/chemical survey of 99 bone biopsies of dialysis patients from dialysis centra all over the world showed elevated concentrations of Sr, as well as increased Sr/calcium ratios in patients suffering from osteomalacia. This observation led to a number of questions, such as: (i) does renal failure cause elevated Sr concentrations in bone, (ii) are increased Sr concentrations in bone either the cause or the consequence of osteomalacia, (iii) does Sr contribute to the development of "aluminum-related" osteomalacia? In this research project we will try to find answers to these questions.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Schrooten Iris

Research team(s)

Project type(s)

• Research Project

Abstract

The risk of occupatianal exposure will be investigated retrospectively using a case-control study design. Cases (200 IDDM patients with chronic renal failure) and controls (200 IDDM patients without renal failure) will be investigated using a standardised questionnaire. Possible exposure will be scored blindly by hygienists on the hand of separate job descriptions. Odds ratio's will be calculated based on the exposure scores and rigorously controlled for confounders.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Pure cultures of human proximal and distal tubular cells and kidney interstitial fibroblasts, and cucultures, are used to investigate the expression of signaling molecules in basal conditions and after injury, and to determine the influence of inflammatory cells and their mediators on cell proliferation and extracellular matrix production.

Researcher(s)

• Promoter: Nouwen Etienne
• Co-promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Do sublethally stressed tubular epithebral cells, liberate chemotactic factors and/or cytokines that attract or activate monocytes, macrophages and fibroblasts ?

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Helbert Mark

Research team(s)

Project type(s)

• Research Project

Abstract

Renal tissue regeneration after unavoidable ischemia/reperfusion injury seems to be delayed in case of kidney transplantation, most probably due to the use of immunosuppressive drugs, e.g. cyclosporin A. Early functional and morphological events of severe post-ischemia/reperfusion injury and regeneration were investigated qualitatively and semi-quantitatively. This delayed regeneration is concommittant with a less prominent interstitial leucocyte infiltrate, suggesting a role for these cells in the repair proces after acute renal failure. The composition of this infiltrate and its kinetics and distribution in relation to the kinetics of tubular injury and repair in this ischemialreperfusion model in the rat is subject of investigation.

Researcher(s)

• Promoter: Eyskens Erik J M G
• Co-promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

In the frame of this project, silicon will be measured in biological fluids at several time points and in tissues at sacrifice after administration of silicon-enriched preparations. By calculating the area under the time- concentration curve, renal excretion, it will be checked which preparation can be used as a food supplement in animals.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

This project is dedicated to the improvement of the social integration and human dignity of several disabled MS patients by the application of electronics. Special attention will be paid to the remaining physical abilities (eye and tongue movements). A universal man-machine interface adapted to individual needs will be developed.

Researcher(s)

• Promoter: Brutsaert Dirk
• Co-promoter: De Broe Marc
• Co-promoter: Herman Arnold

Research team(s)

Project type(s)

• Research Project

Abstract

In a case-control study in Flanders, Groningen (Nl.) and the North of Italy, occupational exposure to siliconcontaining compounds is scored in a retrospective way by patients with ANCA-positive glomerulonephritis and compared with healthy control persons (sex and age matched) (epidemiological part). Toxicity of the siliconparticles on lung and kidney is evaluated by analysis of parameters such as creatinine, PLAP, ANCA, Si, ... in blood, urine and BAL samples (toxicological part) and by determination of their morphology and chemical composition (chemical part). The techniques used in this project are ETAAS, ELISA, agglutination and EM.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Rombaut Ann

Research team(s)

Project type(s)

• Research Project

Abstract

A histological/chemical survey of 99 bone biopsies of dialysis patients from dialysis centra all over the world showed elevated concentrations of Sr, as well as increased Sr/calcium ratios in patients suffering from osteomalacia. This observation led to a number of questions, such as: (i) does renal failure cause elevated Sr concentrations in bone, (ii) are increased Sr concentrations in bone either the cause or the consequence of osteomalacia, (iii) does Sr contribute to the development of "aluminum-related" osteomalacia? In this research project we will try to find answers to these questions.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Schrooten Iris

Research team(s)

Project type(s)

• Research Project

Abstract

In the present study, we will investigate the efficacy of starch containing dialysis fluids and compare this to that of a 4.25 glucose solution in this way aiming to avoid glucose-related side-effects and facilitate a sustained ultrafiltration. Moreover, we will assess the therapeutic safety of the starch solutions to that of the glucose-containing fluids. Finally, the pharmacokinetic characteristics of the starch derivatives will be studied.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

This study, aiming to study the association between occupational exposure to silicon-containing compounds and the development of ANCA-positive glomerulonephritis, consists in 4 interdependent parts. A case-control study will determine the risk ratio of nephrotoxicity after silica- exposure. In a toxicological part, broncho-alveolar lavage fluid will be investigated. During a chemical analysis, the identificatian/specification of the silicon particle will be studied. A experimental part aims to obtain more insight in the pathophysiological mechanism using a ratmodel with inhalation of silica particles.

Researcher(s)

• Promoter: De Broe Marc
• Co-promoter: De Backer Wilfried
• Co-promoter: De Clerck Luc
• Co-promoter: D'Haese Patrick
• Co-promoter: Nouwen Etienne

Research team(s)

Project type(s)

• Research Project

Abstract

In the project the (1) relationship between the exposure to silicon compounds and the prevalence of ANCA-positive glomerulonephritis (2) the value of BAL for the evaluation of exposure to silicon compounds (3) the type and the composition of silicon compounds in the working environment responsible for the development of ANCA's be investigated and an experimental rat model be developed.

Researcher(s)

• Promoter: De Broe Marc
• Co-promoter: De Backer Wilfried
• Co-promoter: De Clerck Luc

Research team(s)

Project type(s)

• Research Project

Abstract

Do sublethally stressed tubular epithebral cells, liberate chemotactic factors and/or cytokines that attract or activate monocytes, macrophages and fibroblasts ?

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Helbert Mark

Research team(s)

Project type(s)

• Research Project

Abstract

By using the hybridoma technology, we will try to raise monoclonal antibodies directed against antigens that are specific for the urothelial carcinomas seen in the context of analgesic abuse and Balkan Endemic nephropathy. Next, on the basis of these antibodies, an assay-system for the detection of these antigens in urine samples will be developed.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

A cohort of 60 children living in the neighbourhood of a lead smelter (Hoboken) and 60 controls will be investigated with a questionnaire and urine sampling. On all urine samples collected (n=400 children of Belgium, Italy and Germany), IAP, TNAP, NAG and a newly developed test, Epidemeral growth factor, will be determined.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

A cohort of 60 children living in the neighbourhood of a lead smelter (Hoboken) and 60 controls will be investigated with a questionnaire and urine sampling. On all urine samples collected (n=400 children of Belgium, Italy and Germany), IAP, TNAP, NAG and a newly developed test, Epidemeral growth factor, will be determined.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

In the first part of this multicentre study, blood samples of hemodialysis patients with known antibodies for HCV, are further analysed for viremia with PCR and his virus subtyping performed with Inno-Lipa. In the second part of this study, therapeutic response during and after a sixth's month course of treatment with recombinant Interferon alpha will be evaluated in these patients with biopsy proven active hepatitis. Possible correlations with virus subtyping will be analyzed.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

It will be investigated whether the uptake of aluminium by the parathryoidgland happens via transferrin mediated endocytosis and to which extent this uptake mechanism interferes with the PTH synthesis/secretion and growth of the parathyroid cell. Moreover, besides aluminium it will be looked for whether sillicon contributes to the high prevalence of adynamic bone in the dialysis population also.

Researcher(s)

• Promoter: D'Haese Patrick
• Co-promoter: De Broe Marc
• Co-promoter: Smans Karine

Research team(s)

Project type(s)

• Research Project

Abstract

Several types of tubuloepithelial cells are isolated from the human kidney, brought into culture, and immortalised by transfection. After optimalisation of the culture conditions, in order to maximally conserve their typical differentiated properties, these cells are being used to unravel the basic mechanics of toxicity for a number of drugs

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Van Der Biest Inge

Research team(s)

Project type(s)

• Research Project

Abstract

Cell lines of different tissue origin and cultures of human proximal and distal tubular cells are compared for their value in replacement of animal model for toxicity testing of different substances at the level of the proximal and distal nephron. Special attention is paid to the role of the isoenzymes of glutathion-S transferase and of the glutation detoxification system.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Bohets Hilde

Research team(s)

Project type(s)

• Research Project

Abstract

Do sublethally stressed tubular epithebral cells, liberate chemotactic factors and/or cytokines that attract or activate monocytes, macrophages and fibroblasts ?

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Helbert Mark

Research team(s)

Project type(s)

• Research Project

Abstract

A study to investigate the pharmacokinetics of lamivudine (GR 109714X) following oral doping in subjects with impaired renal functions.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Pure cultures of human proximal and distal tubular cells and kidney interstitial fibroblasts, and cucultures, are used to investigate the expression of signaling molecules in basal conditions and after injury, and to determine the influence of inflammatory cells and their mediators on cell proliferation and extracellular matrix production.

Researcher(s)

• Promoter: Nouwen Etienne
• Co-promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Cell lines of different tissue origin and cultures of human proximal and distal tubular cells are compared for their value in replacement of animal model for toxicity testing of different substances at the level of the proximal and distal nephron. Special attention is paid to the role of the isoenzymes of glutathion-S transferase and of the glutation detoxification system.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Bohets Hilde

Research team(s)

Project type(s)

• Research Project

Abstract

Study of factors involved in the regeneration of proximal tubular cells and in fibrotic reactions. For this study 3 different toxicity models are available.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verstrepen Walter

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

This study aims to establish whether heavy metals organic solvents contribute to the development of chronic renal failure. It is a case-control study comparing exposure of 300 chronic renal failure patients with 300 controls retrospectively. Exposure will be objectively evaluated by experts.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

This study will develop new screening tests for nephrotoxicity. These tests will be validated in a cross-sectional and longitudinal study of groups of workers at risk and their controls. New tests will be compared to established tests. Particularly the value of intestinal alkaline phosphatase (a specific marker of the S3-segment) will be investigated

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

This prospective study aims to investigate the early renal effects of proven analgesic abuse. A cohort of 200 active analgesic abusers (abuse = daily use of analgesics with a minimal amount of 1000 units) and their matched controls are investigated once a year during eight years (1984-1992) with a short interview and a medical examination.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

This study will develop new screening tests for nephrotoxicity. These tests will be validated in a cross-sectional and longitudinal study of groups of workers at risk and thier controls. New tests will be compared to established tests. Particularly the value of intestinal alkaline phosphatase (a specific marker of the S3-segment) will be investigated.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Cyclosporine is one of the basic therapies after kidney-, heart- and liver transplantation and is also used for the treatment of systemic diseases, but is toxic for the kidney. We will try to find an answer to the following question : which growth factors play a role in the initiation and development of interstitial fibrosis in the kidney during chronic cyclosporine administration. An experimental animal model will be used.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verpooten Gert

Research team(s)

Project type(s)

• Research Project

Abstract

Cell lines of different tissue origin and cultures of human proximal and distal tubular cells are compared for their value in replacement of animal model for toxicity testing of different substances at the level of the proximal and distal nephron. Special attention is paid to the role of the isoenzymes of glutathion-S transferase and of the glutation detoxification system.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Bohets Hilde

Research team(s)

Project type(s)

• Research Project

Abstract

Study of factors involved in the regeneration of proximal tubular cells and in fibrotic reactions. For this study 3 different toxicity models are available.

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verstrepen Walter

Research team(s)

Project type(s)

• Research Project

Abstract

Several types of tubuloepithelial cells are isolated from the human kidney, brought into culture, and immortalised by transfection. After optimalisation of the culture conditions, in order to maximally conserve their typical differentiated properties, these cells are being used to unravel the basic mechanics of toxicity for a number of drugs

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Van Der Biest Inge

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Automated amino acid micro sequencing is an essential tool in modern biochemistry. This technology is used in a variety of projects for : i) determination of total primary structures (globines, lipases) 2) generation of partial sequence data to be used for DNA probe synthesis, peptide synthesis or the identification of the protein concerned.

Researcher(s)

• Promoter: Moens Luc
• Co-promoter: De Broe Marc
• Co-promoter: Gheuens Jan

Research team(s)

Project type(s)

• Research Project

Abstract

Cell communications plays a key role in the normal functioning of any organ. Much is to be learned from the comparative analysis of cell communication in different organs : the heart, the bloodvessel wall, the kidney and in the tumoral tissue.

Researcher(s)

• Promoter: Brutsaert Dirk
• Co-promoter: De Broe Marc
• Co-promoter: Herman Arnold

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Van Der Biest Inge

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verstrepen Walter

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Smans Karine

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Co-promoter: Peetermans Marc
• Co-promoter: Van Oosterom Alan

Research team(s)

Project type(s)

• Research Project

Abstract

Bifunctional antibodies, both directed against the T-cell receptor and against a tumor antigen can activate and target T-cells to the tumor cell which will lyse consecutively. Mainly CD8+ -CD3+ cells contribute during this lytic process. An in vivo model has been developed in which the human tumor marker germ-cell alkaline phosphatase is expressed in the context of an immunocompetent mouse. The therapeutic potential of this model is evaluated.

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Van Der Biest Inge

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Verstrepen Walter

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc
• Fellow: Smans Karine

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: De Broe Marc

Research team(s)

Project type(s)

• Research Project