Creatinine clearance as a substitute for the glomerular filtration rate in the assessment of glomerular hemodynamics.
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A method for the clinical assessment of glomerular hemodynamics has been published previously. We here examined whether, when using this method, renal creatinine clearance (Ccr) can be substituted for the glomerular filtration rate (GFR). The study subjects comprised 57 inpatients from Osaka City General Hospital: 30 with type 2 diabetes mellitus and 27 with chronic glomerulonephritis. During the 2-wk study, patients received a high-salt diet for 1 wk and a low-salt diet for 1 wk. Urinary sodium excretion and systemic blood pressure were measured daily. The renal plasma flow, Ccr, and plasma total protein concentration were also evaluated simultaneously on the last day of the high-salt diet. The GFR was also calculated from the fractional renal accumulation of 99mTc-diethylenetriaminepentaacetic acid (DTPA). Glomerular hemodynamics, represented by the glomerular capillary hydraulic pressure and the resistance of afferent and efferent arterioles, were calculated using the renal clearance, the plasma total protein concentration, and the pressure-natriuresis relationship. Values for renal hemodynamics with the Ccr-derived GFR were compared with those from the 99mTc-DTPA-derived GFR. Ccr values of 53 to 169 ml/min correlated with the 99mTc-DTPA-derived clearance of 39 to 179 ml/min (n=57, r=.71, p<.001). Values for the glomerular pressure and the resistances of afferent and efferent arterioles calculated using the Ccr-derived GFR correlated significantly with those calculated using the 99mTc-DTPA-derived GFR (r=.99, p<.001 and r=.99, p<.001, respectively). These results indicate that the Ccr is an accurate representation of the GFR for use in glomerular hemodynamic analysis of the pressure-natriuresis relationship. (+info)
Lack of chemokine receptor CCR1 enhances Th1 responses and glomerular injury during nephrotoxic nephritis.
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During the development of nephrotoxic nephritis (NTN) in the mouse, we find that a variety of chemokines and chemokine receptors are induced: CCR1 (RANTES, MIP-1alpha), CCR2 (MCP-1), CCR5 (RANTES, MIP-1alpha, MIP-1beta), CXCR2 (MIP-2), and CXCR3 (IP-10). Their timing of expression indicated that CXCR2 and CCR1 are probably important in the neutrophil-dependent heterologous phase of the disease, whereas CCR1, CCR2, CCR5, and CXCR3 accompany the subsequent mononuclear cell infiltration characteristic of autologous disease. We therefore assessed the role of CCR1 in NTN using CCR1(-/-) mice. We found that neutrophil accumulation in CCR1(-/-) mice was comparable to that in wild-type animals but that renal recruitment of CD4(+) and CD8(+) T cells and macrophages increased significantly. Moreover, CCR1(-/-) mice developed more severe glomerulonephritis than did controls, with greater proteinuria and blood urea nitrogen, as well as a higher frequency of crescent formation. In addition, CCR1(-/-) mice showed enhanced Th1 immune responses, including titers of antigen-specific IgG2a antibody, delayed-type hypersensitivity responses, and production of IFN-gamma and TNF-alpha. Lastly, using recombinant proteins and transfected cells that overexpressed CCR1, we demonstrated that MIP-1alpha, but not RANTES, bound CCR1 and induced cell chemotaxis. Thus, rather than simply promoting leukocyte recruitment during NTN, CCR1 expression profoundly alters the effector phase of glomerulonephritis. Therapeutic targeting of chemokine receptors may, on occasion, exacerbate underlying disease. (+info)
The role of selectins in glomerular leukocyte recruitment in rat anti-glomerular basement membrane glomerulonephritis.
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Leukocytes play a central role in the pathogenesis of anti-glomerular basement membrane glomerulonephritis (anti-GBM GN). Understanding the mechanisms underlying their recruitment in the glomerulus is of critical importance, because this may lead to more specific anti-inflammatory drug design. The requirement for integrins, especially from the beta2 group, and their Ig superfamily counter-receptors has been established, however, the role of selectins remains controversial. An intravital microscopy technique was developed to study concomitantly the glomerular and venular leukocyte kinetics and the hemodynamic alterations in a rat model of anti-GBM GN, induced by injection of 10 mg of nephrotoxic serum (NTS). Histologic studies of the kidney were performed in parallel and urinary protein excretion was measured. The animals received NTS alone or were pretreated with either a monoclonal antibody against the beta2 integrin CD11b (OX42, 4 mg/kg) or fucoidan F7 (FF7, 8 mg/kg), an oligosaccharide that blocks both L- and P-selectin function. Administration of NTS resulted in a time-dependent increase in the number of adherent leukocytes in the glomeruli and a parallel decrease of the perfused glomerular capillary area. Substantial proteinuria was observed. Pretreatment with OX42 significantly attenuated these changes. FF7 almost abolished the rolling of the leukocytes in the venules, thus demonstrating efficient anti-selectin activity. Nevertheless, FF7 had no influence on the glomerular events or on the development of proteinuria. These results confirm that glomerular leukocyte adhesion in anti-GBM GN is CD11b-dependent. However, selectin-mediated interaction between the leukocytes and the glomerular capillary endothelium does not appear to be a prerequisite for leukocyte adhesion in the glomerulus. These results therefore question the potential utility of anti-selectin therapy in the treatment of anti-GBM GN. (+info)
Role for interactions between IP-10/Mig and CXCR3 in proliferative glomerulonephritis.
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The mechanisms responsible for mesangial cell proliferation in proliferative glomerulonephritis are only partially understood. This article reports the results of an immunohistochemical study showing high expression of the chemokine receptor CXCR3 by mesangial cells of patients with IgA nephropathy, membranoproliferative glomerulonephritis, or rapidly progressive glomerulonephritis. CXCR3 was also detectable by flow cytometry in cultured human mesangial cells, in which it appeared to be functionally active, as determined by the ability of its ligand, the (interferon-gamma)-inducible protein of 10 kD (IP-10) to induce intracellular Ca2+ influx. Both IP-10 and the monokine induced by interferon-gamma (Mig) were also effective in inducing proliferation of human mesangial cells. These data suggest that in patients with proliferative glomerulonephritis, the chemokines IP-10 and/or Mig not only may act as chemoattractants for infiltrating mononuclear cells in the inflamed tissue, but also may directly induce the proliferation of mesangial cells. (+info)
Heme oxygenase-1 induction attenuates inducible nitric oxide synthase expression and proteinuria in glomerulonephritis.
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In glomerulonephritis, there is intraglomerular activation of inducible nitric oxide synthase (iNOS) leading to high output production of nitric oxide (NO). This can result in supraphysiologic amounts of NO and cause oxidative injury. It is unknown whether mechanisms of cellular defense against NO-mediated injury exist. Induction of the heme catabolizing enzyme heme oxygenase-1 (HO-1), which generates biliverdin, carbon monoxide (CO), and iron (Fe), may provide such a mechanism, as CO and Fe are two negative modulators of iNOS activity and expression. This study assessed whether upregulation of HO-1 by a specific inducer, hemin, negatively modulates iNOS expression and activity in anti-glomerular basement membrane antibody-mediated glomerulonephritis. Glomerular HO-1 expression in nephritic animals was upregulated by treatment with hemin (30 micromol/kg body wt). iNOS and HO-1 mRNA expression were assessed by reverse transcription-PCR of glomerular total RNA from nephritic animals or nephritic animals pretreated with hemin. iNOS activity in glomeruli was measured by assessing conversion of [14C] L-arginine to [14C] L-citrulline. HO-1 protein levels in glomeruli were assessed by Western blot analysis. The effect of hemin treatment on monocyte/macrophage infiltration was assessed by enumeration of ED-1-positive cells in nephritic glomeruli. iNOS and HO-1 were coinduced in nephritic glomeruli. Hemin treatment of nephritic animals resulted in upregulation of glomerular HO-1 levels and a two- to threefold reduction in glomerular iNOS mRNA levels. iNOS activity in glomeruli was significantly reduced in hemin-treated nephritic animals in which proteinuria was also attenuated without a change in monocyte/macrophage infiltration. Hemin (100 to 200 microM) also reduced iNOS protein levels and enzyme activity in cultured mesangial cells stimulated with cytokines. These studies demonstrate that in glomerular immune injury, hemin treatment upregulates glomerular HO-1 with an attendant downregulation of iNOS expression, and thus points to regulatory interaction between the two systems. The beneficial effect of hemin treatment on proteinuria could be linked to downregulation of iNOS. (+info)
Roles of E2F1 in mesangial cell proliferation in vitro.
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Roles of E2F1 in mesangial cell proliferation in vitro. BACKGROUND: The proliferation of mesangial cells is a common feature of many glomerular diseases. E2F transcription factors play an important role in the regulation of the cell cycle. However, the regulation of the mesangial cell cycle and the participation of the E2F family (E2F1 through E2F5) in mesangial cells have not been clarified. Therefore, we investigated the roles of the E2F family in the mesangial cell cycle. METHODS: To elucidate the importance of the E2F family, we investigated the mesangial cell cycle by examining the cell count and thymidine incorporation, and compared it with the protein expression of E2F. Using adenovirus-mediated gene transfer, the cell cycle and apoptosis were examined by measurement of thymidine incorporation, flow cytometry, and caspase 3 activity. We also studied the interaction between E2F1 and G1 cyclins by promoter assay, Western blotting, and CDK kinase assay. RESULTS: E2F1 increased 20-fold in G1/S phase transition. E2F1 overexpression facilitated the mesangial cell cycle and later induced apoptosis. Furthermore, E2F1 overexpression increased the promoter activities and protein expressions of G1 cyclins, cyclin D1, cyclin E, cyclin A. The up-regulation of G1 cyclins contributed to the activation of CDK4 and CDK2. CONCLUSIONS: In mesangial cells, we conclude that E2F1 plays an important role in G1/S phase transition and in apoptosis. E2F1 regulates the mesangial cell cycle through two distinct pathways. First, E2F1 directly transcribes genes that are necessary for DNA synthesis, and second, it promotes cell cycle progression via the induction of G1 cyclins. (+info)
The chemokine receptor antagonist AOP-RANTES reduces monocyte infiltration in experimental glomerulonephritis.
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The chemokine receptor antagonist AOP-RANTES reduces monocyte infiltration in experimental glomerulonephritis. BACKGROUND: This study was designed to evaluate the role of the novel chemokine receptor antagonist amino-oxypentane RANTES (AOP-RANTES), which blocks the binding of macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and RANTES to the chemokine receptor-5 (CCR-5) on the infiltration of monocytes in experimental glomerulonephritis. METHODS: Rats were treated twice daily with 12.5 microg AOP-RANTES following an induction of anti-rat-thymocyte antibody-mediated glomerulonephritis. The white blood cell count, glomerular monocyte infiltration, chemokine expression, and collagen type IV deposition were assessed. RESULTS: The induction of glomerulonephritis increased glomerular monocyte/macrophage (M/M) infiltration at 24 hours and at 5 days was still higher than in controls. AOP-RANTES prevented glomerular M/M infiltration at 24 hours and at 5 days. This was paralleled by reduced glomerular collagen type IV deposition as a fibrotic marker in nephritic animals. CONCLUSION: These data show that the CCR-5 chemokine receptor antagonist AOP-RANTES ameliorates M/M infiltration and improves glomerular pathology in experimental glomerulonephritis. The use of chemokine receptor antagonists may offer a new therapeutic option in inflammatory renal injuries. (+info)
Development of lupus in BXSB mice is independent of IL-4.
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Although systemic lupus erythematosus appears to be a humorally mediated disease, both Th1 and Th2 type responses have been implicated in its pathogenesis. The Th1 response, as exemplified by IFN-gamma production, has been uniformly shown in mouse lupus models to be critical for disease induction. The role of Th2 type responses, however, is more complicated, with some studies showing detrimental and others beneficial effects of IL-4 in these models. To further address this issue, we generated and analyzed IL-4 gene-deficient BXSB mice. Mice homozygous for this deletion had significantly lower serum levels of total IgG1 compared with wild-type BXSB, consistent with the lack of IL-4. However, no significant differences were observed in mortality, spleen weight, severity of glomerulonephritis, levels of anti-chromatin and anti-ssDNA Abs, or frequency of activated (CD44high) CD4+ T cells. The anti-chromatin Ab isotype response was virtually all Th1 type in both the knockout and wild-type BXSB. These findings directly demonstrate that IL-4 and, by inference, Th2 cells are not obligatory participants in the induction and maintenance of lupus in this strain. (+info)