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D J Nikolic-Paterson

Publications and source records attributed to D J Nikolic-Paterson.

At least 19 recordsLinked to original sources
PubMed2006

Monocyte chemoattractant protein-1-induced tissue inflammation is critical for the development of renal injury but not type 2 diabetes in obese db/db mice.

AIMS/HYPOTHESIS: Tissue macrophage accumulation is thought to induce insulin resistance during obesity and stimulate the progression of diabetic nephropathy. Monocyte chemoattractant protein-1 (MCP-1) is a potent stimulator of macrophage recruitment. It is increased in adipose tissue during obesity and in diabetic kidneys, suggesting that inflammation of these tissues may be MCP-1-dependent. Based on these findings, the aim of this study was to examine whether a deficiency in MCP-1 would alter the development of type 2 diabetes and its renal complications. MATERIALS AND METHODS: The role of MCP-1 in the progression of type 2 diabetes and its associated renal injury was assessed in obese db/db mice that were deficient in the gene encoding MCP-1 (Ccl2). RESULTS: The incidence and development of type 2 diabetes were similar in Ccl2(+/+) and Ccl2(-/-) db/db mice between 8 and 32 weeks of age. Body mass, hyperglycaemia, hyperinsulinaemia, glucose and insulin tolerance, plasma triacylglycerol and serum NEFA were not different between these strains. Pathological changes in epididymal adipose tissue, including increases in macrophage accumulation and Tnfa mRNA and reductions in Adipoq mRNA, were unaffected by the absence of MCP-1. In contrast, kidney macrophage accumulation and the progression of diabetic renal injury (albuminuria, histopathology, renal fibrosis) were substantially reduced in Ccl2(-/-) compared with Ccl2(+/+) db/db mice with equivalent diabetes. CONCLUSIONS/INTERPRETATION: Our study demonstrates that MCP-1 promotes type 2 diabetic renal injury but does not influence the development of obesity, insulin resistance or type 2 diabetes in db/db mice. MCP-1 plays a critical role in inflammation of the kidney, but not adipose tissue, during the progression of type 2 diabetes.

Animals↗
PubMed2006

Monocyte chemoattractant protein-1 promotes the development of diabetic renal injury in streptozotocin-treated mice.

Diabetic nephropathy involves a renal inflammatory response induced by the diabetic milieu. Macrophages accumulate in diabetic kidneys in association with the local upregulation of monocyte chemoattractant protein-1 (MCP-1); however, the contribution of macrophages to renal injury and the importance of MCP-1 to their accrual are unclear. Therefore, we examined the progression of streptozotocin (STZ)-induced diabetic nephropathy in mice deficient in MCP-1 in order to explore the role of MCP-1-mediated macrophage accumulation in the development of diabetic kidney damage. Renal pathology was examined at 2, 8, 12 and 18 weeks after STZ treatment in MCP-1 intact (+/+) and deficient (-/-) mice with equivalent blood glucose and hemoglobin A1c levels. In MCP-1(+/+) mice, the development of diabetic nephropathy was associated with increased kidney MCP-1 production, which occurred mostly in tubules, consistent with our in vitro finding that elements of the diabetic milieu (high glucose and advanced glycation end products) directly stimulate tubular MCP-1 secretion. Diabetes of 18 weeks resulted in albuminuria and elevated plasma creatinine in MCP-1(+/+) mice, but these aspects of renal injury were largely suppressed in MCP-1(-/-) mice. Protection from nephropathy in diabetic MCP-1(-/-) mice was associated with marked reductions in glomerular and interstitial macrophage accumulation, histological damage and renal fibrosis. Diabetic MCP-1(-/-) mice also had a smaller proportion of kidney macrophages expressing markers of activation (inducible nitric oxide synthase or sialoadhesin) compared to diabetic MCP-1(+/+) mice. In conclusion, our study demonstrates that MCP-1-mediated macrophage accumulation and activation plays a critical role in the development of STZ-induced mouse diabetic nephropathy.

Animals↗
PubMed2004

Abnormal p38 mitogen-activated protein kinase signalling in human and experimental diabetic nephropathy.

AIMS/HYPOTHESIS: Inflammation and fibrosis are pathological mechanisms that are partially regulated by cell signalling through the p38 mitogen-activated protein kinase (MAPK) pathway. Elements of the diabetic milieu such as high glucose and advanced glycation end-products induce activation of this pathway in renal cells. Therefore, we examined whether p38 MAPK signalling is associated with the development of human and experimental diabetic nephropathy. METHODS: Immunostaining identified phosphorylated (active) p38 MAPK in human biopsies with no abnormality ( n=6) and with Type 2 diabetic nephropathy ( n=12). Changes in kidney levels of phosphorylated p38 were assessed by immunostaining and western blotting in mice with streptozotocin-induced Type 1 diabetes that had been killed after 0.5, 2, 3, 4 and 8 months, and in Type 2 diabetic db/db mice at 2, 4, 6 and 8 months of age. RESULTS: Phosphorylated p38 was detected in some intrinsic cells in normal human kidney, including podocytes, cortical tubules and occasional interstitial cells. Greater numbers of these phosphorylated p38+ cells were observed in diabetic patients, and phosphorylated p38 was identified in accumulating interstitial macrophages and myofibroblasts. A similar pattern of p38 activation was observed in both mouse models of diabetes. In mice, kidney levels of phosphorylated p38 increased (2-6 fold) following the onset of Type 1 and Type 2 diabetes. In both mouse models, interstitial phosphorylated p38+ cells were associated with hyperglycaemia, increased HbA(1)c levels and albuminuria. Further assessment of streptozotocin-induced diabetic nephropathy showed that interstitial phosphorylated p38+ cells correlated with interstitial fibrosis (myofibroblasts, collagen). CONCLUSIONS/INTERPRETATION: Increased p38 MAPK signalling is a feature of human and experimental diabetic nephropathy. Time course studies in mouse models suggest that phosphorylation of p38 plays a pathological role, particularly in the development of interstitial fibrosis.

Animals↗
PubMed2002

IL-10 induces mesangial cell proliferation via a PDGF-dependent mechanism.

Interleukin-10 (IL-10) is a mesangial cell growth factor in vivo and in vitro. However, the mechanism by which IL-10 exerts its mitogenic activity is not known. The aim of this study was to determine whether IL-10 induces mesangial cell proliferation in a PDGF-dependent or independent fashion. A well--characterized rat mesangial cell line (1097) was used in a series of cell proliferation experiments in which cells were serum-starved and then incubated with recombinant IL-10 in the presence or absence of STI 571 (a specific inhibitor of signalling via the PDGF-alpha and beta receptors) or a neutralizing anti-PDGF-AB antibody. IL-10 induced significant mesangial cell proliferation at 24 and 48 h after cytokine addition. This response was inhibited totally by the addition of STI-571, demonstrating that IL-10 mitogenic activity has an absolute requirement for signalling through the PDGF receptor. In further studies, it was found that STI-571 could be added 24 h after IL-10 stimulation and still exert a profound inhibition of IL-10 mitogenic activity. The ability of a neutralizing anti-PDGF-AB antibody to inhibit completely IL-10-induced mesangial cell proliferation confirmed that IL-10 acts via induction of an autocrine PDGF response rather than the possibility that IL-10 may transactivate the PDGF receptor in a PDGF-independent fashion. In conclusion, this study has demonstrated that IL-10 induces mesangial cell proliferation via an autocrine PDGF-mediated mechanism. Thus, therapies which antagonize PDGF signalling will also inhibit any contribution of IL-10 to mesangial proliferation.

Animals↗
PubMed2002

Expression of monocyte chemoattractant protein-1 and macrophage colony-stimulating factor in normal and inflamed rat testis.

Macrophages are numerous in the testicular interstitial tissue under normal conditions and increase during inflammation. The mechanisms involved are poorly characterized. Expression of the macrophage-regulating cytokines monocyte chemoattractant protein (MCP)-1 and macrophage colony-stimulating factor (M-CSF) was examined in the adult rat testis before and after an i.p. injection of an inflammatory stimulus, lipopolysaccharide (LPS). In the normal testis, M-CSF was readily observed using Northern blot and Western blot analysis. In contrast, MCP-1 was not detectable by Northern blot in the normal testis, but was detected using RT-PCR amplification and a sensitive ELISA. After LPS treatment, testicular MCP-1 mRNA and protein expression increased dramatically (up to 400-fold). In-situ hybridization for MCP-1 revealed that production was confined to the interstitium of the inflamed testis, in Leydig cells, peritubular cells, perivascular cells and monocyte-like macrophages, but not in tissue-resident macrophages. Unlike MCP-1, M-CSF mRNA and protein expression in the testis increased only marginally, if at all, after LPS treatment. These results suggest that MCP-1 stimulates the increase in intratesticular macrophages that accompanies LPS-induced inflammation in vivo. Together with M-CSF, MCP-1 may also play a role in maintaining the resident macrophage population of the normal testis.

Animals↗
PubMed2001

Urine macrophage migration inhibitory factor concentrations as a diagnostic tool in human renal allograft rejection.

BACKGROUND: Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that is a potent activator of macrophages and T cells. Previous studies have shown that local MIF production is increased in acute renal allograft rejection, suggesting that it may play an important role in the rejection process. AIMS: To determine if urine and serum MIF concentrations: (1) are increased in acute rejection, and (2) can be used as noninvasive tools to discriminate between acute rejection (AR) and cyclosporine nephrotoxicity (CyA toxicity). METHODS: In a prospective study of nine renal allograft patients (five acute rejection and four stable), serial urine MIF concentrations were measured by ELISA in the first 14 days after transplantation. In a retrospective study, MIF concentrations in urine and serum were measured in 24 patients who were biopsied for acute renal transplant dysfunction (11 AR, 13 CyA toxicity). Urine and serum MIF were also measured in 23 stable renal transplant patients and 10 normals. RESULTS: MIF was readily detected in the urine of normal healthy controls (106+/-61 pg/micromol creatinine). In the prospective study, the urinary MIF concentration was increased substantially on day 1 posttransplantation and subsequently fell in parallel with the serum creatinine. However, urine MIF increased before episodes of biopsy proven acute rejection. The retrospective study showed that urine MIF concentrations in patients with AR were increased 5-fold compared to normal controls (439+/-313 pg/micromol Cr; P<0.01). In contrast, urine MIF concentrations in CyA toxicity were not significantly different to normal controls (145+/-119 pg/micromol Cr; P=NS). A marked increase in MIF immunostaining was seen in biopsies of AR, but not in CyA toxicity. No significant differences were evident in serum MIF levels between normals and any transplant patient group. CONCLUSIONS: These results suggest that measurement of urine MIF concentration may be useful in monitoring renal transplant patients for acute rejection and as a discriminator from cyclosporine nephrotoxicity.

Adult↗
PubMed2001

Glomerular permselectivity factors are not responsible for the increase in fractional clearance of albumin in rat glomerulonephritis.

The increased fractional clearance of albumin in nephrotic states has long been attributed to glomerular permselectivity dysfunction. Using radiolabeled rat serum albumin, transferrin, IgG, and polydisperse Ficoll, this study investigated the changes in their in vivo fractional clearance in puromycin aminonucleoside nephrosis and anti-glomerular basement membrane glomerulonephritis. In control rats the lack of charge selectivity was confirmed by the demonstration that carboxymethyl Ficoll (valence approximately -39) had the same fractional clearance as uncharged Ficoll. Both diseases exhibited similar effects on fractional clearance measurements suggesting an underlying common mechanism. In disease, there was good agreement between the fractional clearance of proteins determined by radioactivity as compared to those determined by radioimmunoassay. A small increase in the fractional clearance for IgG was evident in disease as compared to controls, which mirrored the change in the equivalent size Ficoll, suggesting that the increase is because of the development of a small proportion of large pores in the glomerular capillary wall. There was no increase, however, in the fractional clearance of Ficoll of equivalent size to albumin in either disease, yet the fractional clearance of the albumin increased by 12 to 14 times as determined by radioactivity and 4500 to 6600 times as determined by radioimmunoassay. This study demonstrates that glomerulonephritis is not a disease associated with changes in glomerular permeability to albumin but is because of alterations in albumin processing by cells distal to the glomerular basement membrane. It is also apparent that approaches to glomerular pathology and proteinuria as risk factors in renal disease must be reassessed.

Animals↗
PubMed2001

Interleukin-1 induces tubular epithelial-myofibroblast transdifferentiation through a transforming growth factor-beta1-dependent mechanism in vitro.

Interleukin-1 (IL-1) has been shown to exert profibrotic activity in a number of disease models, including crescentic glomerulonephritis and pulmonary fibrosis, but the mechanisms by which this operates are poorly understood. Recent studies have identified a novel mechanism promoting renal fibrosis: tubular epithelial-myofibroblast transdifferentiation (TEMT). The present study examined whether IL-1 can stimulate TEMT in vitro. Cells of the normal rat kidney tubular epithelial cell line (NRK52E) were grown to confluence on collagen-coated plates and cultured for 5 days in the presence 1 to 20 ng/mL of IL-1alpha. Doses of 10 to 20 ng/mL of IL-1 caused transdifferentiation of NRK52E cells into myofibroblast-like cells. Scanning electron microscopy identified IL-1-induced morphological changes as a loss of apical-basal polarity and microvilli, cell hypertrophy, and the development of an elongated and invasive appearance. Phenotypically, IL-1-induced TEMT was characterized by de novo messenger RNA and protein expression of the mesenchymal marker alpha-smooth muscle actin, shown by Northern blotting, immunohistochemistry, and Western blotting. This was accompanied by loss of the epithelial marker E-cadherin. The addition of an excess of IL-1-receptor antagonist completely inhibited IL-1-induced TEMT. IL-1 was shown to stimulate the secretion of active transforming growth factor-beta1 (TGF-beta1) by NRK52E cells. Furthermore, the addition of a neutralizing anti-TGF-beta1 antibody inhibited IL-1-induced TEMT. In conclusion, IL-1 is a profibrogenic cytokine capable of inducing TEMT through a TGF-beta1-dependent mechanism. This may represent a novel mechanism by which IL-1 induces renal fibrosis in vivo.

Actins↗
PubMed2001

LF15-0195 prevents the induction and inhibits the progression of rat anti-GBM disease.

BACKGROUND: LF15-0195 is a novel immunosuppressant that is currently in phase II clinical trials for the treatment of vasculitis. This study examined whether LF15-0195 could suppress the induction and progression of rat anti-glomerular basement membrane (anti-GBM) glomerulonephritis. METHODS: Rapidly progressive glomerulonephritis was induced in primed rats by the administration of anti-GBM serum. In the first experiment, LF15-0195 was given daily by subcutaneous injection (days 0 to 14) to treat the induction of anti-GBM disease analyzed at day 14. In a second experiment, rats received LF15-0195 as an intervention treatment from days 7 to 28 (continuous therapy) or days 7 to 12 (pulse therapy) to treat the progression of disease assessed at day 28. RESULTS: Continuous LF15-0195 treatment during the induction of anti-GBM disease (experiment 1) prevented proteinuria and loss of renal function, and markedly reduced histological kidney lesions and renal fibrosis. LF15-0195 also reduced kidney leukocyte infiltrate, urine excretion of interleukin-1beta (IL-1beta) and transforming growth factor-beta (TGF-beta), and the serum antibody response, but not kidney deposition of Ig and C3. When LF15-0195 treatment was initiated at day 7, both continuous and pulse therapy partially inhibited disease progression by suppressing the loss of renal function, interstitial macrophage and T-cell accumulation, tubular cell proliferation, and renal fibrosis. CONCLUSION: LF15-0195 prevents the induction and suppresses the progression of rat anti-GBM disease through multiple mechanisms of action, suggesting that this drug may have significant therapeutic potential in human glomerulonephritis. The similar efficacy of continuous and pulse intervention treatment in this model indicates that short-term LF15-0195 treatment may achieve optimal benefit without prolonged bone marrow suppression.

Animals↗
PubMed2001

PDGF signal transduction inhibition ameliorates experimental mesangial proliferative glomerulonephritis.

BACKGROUND: Platelet-derived growth factor (PDGF) has been consistently implicated in the cell proliferation and extracellular matrix accumulation, which characterize progressive glomerular disease. In the present study, the effects of a potent and selective inhibitor of PDGF receptor tyrosine kinase, STI 571, were examined in vitro and in vivo. METHODS: Cultured mesangial cells were incubated with PDGF (50 ng/mL) and fibroblast growth factor-2 (FGF-2; 50 ng/mL) and treated with STI 571 (0.13 to 2.0 micromol/L). Experimental mesangial proliferative glomerulonephritis was induced in male Wistar rats with monoclonal OX-7, anti-rat Thy-1.1 antibody with rats randomized to receive either STI 571 (50 mg/kg intraperitoneally daily) or vehicle. Animals were examined six days later. RESULTS: In vitro, both PDGF and FGF-2 induced a threefold increase in mesangial cell 3H-thymidine incorporation. STI 571 reduced PDGF but not FGF-2-stimulated mesangial cell proliferation in a dose-dependent manner, with complete abolition at 0.4 micromol/L. In animals with Thy-1.1 glomerulonephritis, PDGF receptor tyrosine kinase blockade was associated with significant reductions in mesangial cell proliferation (P < 0.001), the number of activated (alpha-smooth muscle positive) mesangial cells, and glomerular type IV collagen deposition (P < 0.001). CONCLUSION: The amelioration of the pathological findings of experimental mesangial proliferative glomerulonephritis by blockade of PDGF receptor activity suggests the potential clinical utility of this approach as a therapeutic strategy in glomerular disease.

Animals↗
PubMed2001

Tubules are the major site of M-CSF production in experimental kidney disease: correlation with local macrophage proliferation.

BACKGROUND: Local proliferation of macrophages occurs within both the glomerulus and the interstitium in severe forms of human and experimental glomerulonephritis and plays an important role in amplifying renal injury. Macrophage colony-stimulating factor (M-CSF) is thought to be the growth factor driving this local macrophage proliferation. Previous studies have found that glomeruli are the predominant source of M-CSF production. However, this is difficult to reconcile with the prominent macrophage accumulation and proliferation seen in the interstitial compartment in glomerulonephritis. To address this issue, we localized M-CSF expression in rat models of glomerular versus tubulointerstitial injury and examined its relationship to local macrophage proliferation. METHODS: M-CSF expression (Northern blotting, in situ hybridization, immunostaining, Western blotting) and local macrophage proliferation (double immunostaining) was examined in normal rat kidney on days 1 and 14 of rat anti-glomerular basement membrane (anti-GBM) glomerulonephritis and on day 5 following unilateral ureteric obstruction. RESULTS: M-CSF mRNA and protein expression were identified in small numbers of glomerular podocytes, approximately 25% of cortical tubules, and most medullary tubules in normal rat kidney. Northern blotting showed a significant increase in whole kidney M-CSF mRNA in rat anti-GBM glomerulonephritis. Up-regulation of glomerular and, most prominently, tubular M-CSF production was confirmed by three independent methods: in situ hybridization, immunostaining, and Western blotting. The increase in M-CSF expression colocalized with local macrophage proliferation (ED1+PCNA+ cells) in both the glomerulus and tubulointerstitium. On day 5 after ureter ligation, there was a significant increase in tubular M-CSF mRNA and protein expression in the obstructed kidney, with no change in glomerular M-CSF. In parallel with M-CSF expression, macrophage accumulation and proliferation was prominent in the interstitium, but was absent from glomeruli. CONCLUSIONS: The tubular epithelial cell is the major site of M-CSF production within the injured kidney. Indeed, substantial macrophage accumulation and local proliferation can occur in the tubulointerstitium in the absence of glomerular inflammation. These results suggest that M-CSF production within the kidney, particularly by tubular epithelial cells, plays an important role in regulating local macrophage proliferation in experimental kidney disease.

Animals↗
PubMed2001

Tubular phenotypic change in progressive tubulointerstitial fibrosis in human glomerulonephritis.

There is much debate over the origins of fibroblast-type cells that accumulate in interstitial fibrosis. A controversial hypothesis, supported by data from animal and cell-culture studies, is that fibroblast-type cells can derive from tubular epithelial cells by a process of epithelial-mesenchymal transdifferentiation. However, to date, no evidence supports this postulate in human glomerulonephritis. This study sought to provide evidence that tubular epithelial cells can undergo phenotypic change toward a fibroblast-like cell in human glomerulonephritis. One hundred twenty-seven open renal biopsy specimens from patients with minimal change disease (MCD), immunoglobulin A (IgA) nephropathy, and rapidly progressive glomerulonephritis (RPGN) were examined for tubular phenotypic change by two-color immunohistochemistry using the criteria of de novo expression of alpha-smooth muscle actin (alpha-SMA), a myofibroblast marker; loss of the epithelial marker cytokeratin; and collagen production. In normal human kidney and MCD, tubular epithelial cells expressed cytokeratin with no evidence of alpha-SMA staining. However, in 36 of 90 cases of IgA nephropathy and 9 of 18 cases of RPGN, small numbers of tubular epithelial cells in areas of fibrosis showed de novo alpha-SMA expression, accounting for 0.4% +/- 0.2% (IgA nephropathy) and 3.8% +/- 1.5% (RPGN) of cortical tubules. An intermediate stage of phenotypic change was observed in some cuboidal epithelial cells that expressed both cytokeratin and alpha-SMA. Tubules containing alpha-SMA-positive (alpha-SMA(+)) cells also stained for collagen types I and III, suggesting that tubular cells undergoing phenotypic change have an active role in the fibrotic process. There also was a marked increase in transforming growth factor-beta1 (TGF-beta1) tubular expression in areas with interstitial fibrosis, including tubules with phenotypic change. There was a highly significant correlation between tubular alpha-SMA expression and interstitial fibrosis, interstitial alpha-SMA(+) myofibroblast accumulation, deposition of collagen types I and III, tubular TGF-beta1 expression, and renal dysfunction. In conclusion, this study provides evidence that tubular epithelial cells can undergo phenotypic change toward a myofibroblast-like phenotype on the basis of de novo alpha-SMA expression, loss of cytokeratin, and de novo collagen staining. These data, although not conclusive, provide the first support for the hypothesis that transdifferentiation of tubular epithelial cells has a role in progressive renal fibrosis in human glomerulonephritis.

Actins↗
PubMed2001

Local macrophage proliferation correlates with increased renal M-CSF expression in human glomerulonephritis.

BACKGROUND: Macrophage accumulation is a prominent feature in many forms of glomerulonephritis. Local proliferation of macrophages within the kidney has been described in human and experimental glomerulonephritis and may have an important role in augmenting the inflammatory response. The current study examined the relationship between local macrophage proliferation and renal expression of macrophage colony-stimulating factor (M-CSF). METHODS: A total of 118 renal biopsies of patients with a wide range of glomerulonephridities were examined for M-CSF protein and macrophage proliferation (KP1+PCNA+cells) by single and double immunohistochemistry staining, respectively. RESULTS: Biopsies of thin membrane disease (TMD) with histologically normal kidney showed M-CSF protein expression by 33% of cortical tubules, while glomerular M-CSF expression was limited to resident macrophages and some podocytes. Glomerular M-CSF expression increased significantly in proliferative forms of glomerulonephritis, with M-CSF staining of infiltrating macrophages, podocytes and some mesangial cells. Segmental areas of strong M-CSF expression, particularly in crescents, co-localized with KP1+PCNA+ proliferating macrophages. There was also an increase in tubular M-CSF expression in most types of glomerulonephritis. Tubular M-CSF staining was strongest in areas of tubular damage and co-localized with KP1+ macrophages, including KP1+PCNA+ proliferating macrophages. Many interstitial macrophages and alpha-smooth muscle actin-positive myofibroblasts showed strong M-CSF staining. Statistical analysis showed a highly significant correlation between M-CSF expression and local macrophage proliferation in both the glomerulus and tubulointerstitium. Glomerular and tubular M-CSF expression gave a significant correlation with renal dysfunction. CONCLUSIONS: Glomerular and tubulointerstitial M-CSF expression is up-regulated in human glomerulonephritis, being most prominent in proliferative forms of disease. This correlated with local macrophage proliferation, suggesting that increased renal M-CSF production plays an important role in regulating local macrophage proliferation in human glomerulonephritis.

Adult↗
PubMed2001

The role of macrophages in glomerulonephritis.

Macrophage accumulation is a prominent feature in most types of human glomerulonephritis. In particular, tubulointerstitial macrophage accumulation correlates with the degree of renal dysfunction and is predictive of disease progression. Depletion studies have shown that macrophages can induce glomerular injury in experimental glomerulonephritis. Moreover, recent studies targeting chemokines and adhesion molecules have shown that inhibiting macrophage accumulation can suppress progressive renal injury in animal models of glomerulonephritis. Macrophages can produce many molecules with the potential to cause renal damage, although the precise mechanism(s) of macrophage-mediated renal injury have yet to be determined. It is now evident that tubules-a major source of chemokines and adhesion molecules-play an active role in promoting interstitial macrophage infiltration and activation. Thus, targeting pro-inflammatory functions of tubular epithelial cells may be an effective means to inhibit macrophage-mediated tubulointerstitial injury without causing systemic immunosuppression.

Animals↗
PubMed2000

Characteristics of albumin processing during renal passage in anti-Thy1 and anti-glomerular basement membrane glomerulonephritis.

Recent studies have shown that glomerular-filtered albumin appears to be processed by two distinct cellular pathways. The major pathway, a high-capacity retrieval pathway, returns most of the filtered albumin to the blood supply intact. The albumin not taken up by the retrieval pathway is degraded by lysosomes during renal passage and excreted as fragments in urine. We studied the interplay of the albumin retrieval pathway and the degradation pathway in the disease models of anti-Thy1 nephritis, a model of mild proteinuria, and anti-glomerular basement membrane (anti-GBM) disease, a model of severe proteinuria. This is achieved by investigating the integrity of urinary albumin and its excretion rate. Total albumin excretion (intact plus fragments) did not change significantly in the rats with anti-Thy1 nephritis. However, it was established that intact albumin excretion had a strong positive correlation with increasing total-protein excretion, which showed that the degradation pathway was being predominantly affected in this disease. For the rats with anti-GBM disease, total protein excretion increased 26-fold compared with the control group, and intact albumin excretion increased 250-fold. The profound changes in albumin excretion in anti-GBM disease are consistent with inhibition primarily of the retrieval pathway.

Albumins↗
PubMed2000

Up-regulation of the tumour-associated marker CD44V6 in experimental kidney disease.

CD44 is an adhesion molecule involved in a wide range of cell-cell and cell-matrix interactions. The standard form of CD44 (CD44S) is a 85-90-kD glycoprotein, but alternative splicing of RNA encoding 10 variable exons (V1-V10) can give rise to many different CD44 variant protein isoforms of higher molecular weight. CD44 isoforms containing the V6 exon play a crucial role in tumour metastasis and lymphocyte activation. However, the role of CD44V6 in the kidney is unknown. The aim of this study was to examined renal CD44V6 expression in health, disease and in vitro. Immunohistochemistry staining with the V6-specific 1.1ASML antibody identified constitutive CD44V6 expression by occasional cortical tubular epithelial cells and medullary tubules in normal rat kidney. In immune-induced kidney disease (rat anti-glomerular basement membrane glomerulonephritis), there was a marked increase in CD44V6 expression by cortical tubules, particularly in areas of tubulointerstitial damage, which was associated with focal macrophage infiltration. There was also a marked increase in CD44V6 expression by damaged tubules in a model of non-immune kidney disease (unilateral ureteric obstruction). Reverse transcription-polymerase chain reaction revealed a complex pattern of CD44V6-containing mRNA isoforms in normal rat kidney. This pattern of CD44V6 splicing was essentially unaltered in disease. The NRK52E normal rat kidney tubular epithelial cell line expresses both CD44S and CD44V6. Stimulation of NRK52E cells with IL-1 or transforming growth factor-beta 1 induced a two-to-five-fold increase in the expression of both CD44S and CD44V6. Furthermore, triggering of NRK52E cells by antibodies to CD44S or CD44V6, but not isotype control antibodies, induced secretion of monocyte chemoattractant protein-1. In conclusion, this study has identified expression of the tumour-associated marker CD44V6 in tubular epithelial cells in normal and diseased rat kidney, and suggests that signalling through the CD44V6 molecule may participate in the pathogenesis of experimental kidney disease.

Animals↗
PubMed2000

Expression of macrophage migration inhibitory factor in human glomerulonephritis.

BACKGROUND: We have recently demonstrated that macrophage migration inhibitory factor (MIF) plays a pathogenic role in experimental glomerulonephritis (GN). The aim of the current study was to investigate MIF expression in human GN. METHODS: MIF expression was examined by in situ hybridization and immunohistochemistry staining in 65 biopsies from a variety of glomerulonephridities. RESULTS: There is constitutive expression of MIF mRNA and protein in normal human kidney that is largely restricted to tubular epithelial cells and to some glomerular epithelial cells. There was little change in the pattern of MIF expression in nonproliferative forms of GN such as minimal change disease and membranous GN. However, there was a marked increase in both glomerular and tubular MIF expression in proliferative forms of GN, including focal segmental glomerulosclerosis (FGS), lupus nephritis, crescentic GN, and mesangiocapillary proliferative GN. The prominent macrophage and T-cell infiltrate in these diseases were largely restricted to areas with marked up-regulation of MIF expression, contributing to glomerular hypercellularity, glomerular focal segmental lesions, crescent formation, tubulitis, and granulomatous lesions. De novo MIF expression was evident in glomerular endothelial cells and mesangial cells in proliferative forms of GN. In addition, many infiltrating macrophages and T cells showed MIF mRNA and protein expression. Quantitative analysis found that increased glomerular and tubular MIF expression gave a highly significant correlation with macrophage and T-cell accumulation, the severity of histologic lesions, and the loss of creatinine clearance. CONCLUSIONS: Renal MIF expression is markedly up-regulated in proliferative forms of human GN, and this correlates with leukocyte infiltration, histologic damage, and renal function impairment. These results suggest that MIF may be an important mediator of renal injury in progressive forms of human GN. Based on these findings, together with the known pathogenic role of MIF in experimental GN, we propose that MIF is an attractive therapeutic target in the treatment of progressive forms of GN.

Adolescent↗