核因子-κB/IκB信号通路介导实验性肾炎肾组织中单核细胞趋化蛋白-1表达

目的　探讨核因子 κB(NF κB) /IκB信号通路在肾毒血清性肾炎肾组织单核细胞趋化蛋白 1(MCP 1)表达中的作用。方法　肾毒血清肾炎应用兔抗鼠肾小球基底膜肾毒血清制备。应用凝胶电泳迁移率 (EMSA)和Western印迹检测肾毒血清肾炎大鼠肾组织中NF κB活化、p6 5亚基核转位以及IκBα和IκBβ的降解 ;采用免疫组织化学及核酸酶保护法检测肾组织中MCP 1表达 ,并分析其与NF κB活化的关系。结果　模型组肾小球及肾小管中MCP 1表达分别为 (2 4 37± 7 0 6 )个 /肾小球横切面和 (5 4 78± 11 4 9) % ,较正常对照组显著升高 (P <0 0 1) ;肾组织中NF κB活化显著增强 ,p6 5由胞质转移至胞核 ,胞质内IκBα和IκBβ降解明显增加 ;NF κB活化与MCP 1表达呈显著正相关。 结论　NF κB/IκB信号通路介导肾小球肾炎肾组织中MCP 1表达。     

Mononuclear cell-infiltrate inhibition by blocking macrophage-derived chemokine results in attenuation of developing crescentic glomerulonephritis

Glomerular monocyte/macrophage (Mo/M phi) infiltrates play a role in many forms of glomerulonephritis (GN), and the intensity of Mo/M phi trafficking correlates with the loss of renal function and histological damage. We analyzed the functional role of macrophage-derived chemokine (MDC), a potent mononuclear cell chemoattractant, during the progression of anti-glomerular basement membrane (GBM) antibody (Ab) GN, a model of crescentic GN in the WKY rat, and whether the effects of MDC were dependent on its receptor CCR4. MDC mRNA and protein expression were markedly induced in nephritic glomeruli throughout the disease. Blocking the function of MDC did not affect the developing of the disease from days 2 to 7, but it dramatically blocked M omicron/M phi infiltration in the glomeruli, prevented crescent formation, and reversed renal function impairment during days 7 to 14 of the anti-GBM GN. In this study, we also found that MDC activity on M omicron/M phi in this GN was at least partly dependent on a new variant of CCR4. These results suggest that MDC is critically involved in the development of anti-GBM GN from acute glomerular injury to irreversible tissue damage. In addition, an antagonist to MDC may represent a prime drug target for therapeutic application to intervene in the progression of anti-GBM GN and in other M omicron/M phi-dominant GN.     

Urinary cystatin C as a renal biomarker and its immunohistochemical localization in anti-GBM glomerulonephritis rats

The usefulness of urinary cystatin C for the early detection of renal damage in anti-glomerular basement membrane (GBM) glomerulonephritis rats was investigated and compared to other biomarkers (β2-microglobulin, calbindin, clusterin, epidermal growth factor (EGF), alpha-glutathione S-transferase (GST-α), mu-glutathione S-transferase (GST-μ), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), osteopontin, tissue inhibitor of metalloprotease-1 (TIMP-1), and vascular endothelial growth factor (VEGF)). Urinary levels of cystatin C increased in anti-GBM glomerulonephritis rats, whereas the conventional markers, plasma creatinine and UN did not, demonstrating its usefulness for the early detection of renal damage associated with anti-GBM glomerulonephritis. As well as cystatin C, urinary β2-microglobulin, clusterin, GST-α, GST-μ, KIM-1, and NGAL also had the potential to detect renal damage associated with anti-GBM glomerulonephritis.Furthermore, the immunohistochemical localization of cystatin C in the kidney was examined. Cystatin C expression was mainly observed in the proximal renal tubules in anti-GBM glomerulonephritis rats, and its expression barely changed with the progression of glomerulonephritis. Cystatin C expression was also observed in the tubular lumen of the cortex and medulla when glomerulonephritis was marked, which was considered to be characteristic of renal damage.In conclusion, urinary cystatin C, β2-microglobulin, clusterin, GST-α, GST-μ, KIM-1, and NGAL could be useful biomarkers of renal damage in anti-GBM glomerulonephritis rats. Immunohistochemical cystatin C expression in the proximal renal tubules was barely changed by the progression of glomerulonephritis, but it was newly observed in the tubular lumen when renal damage was apparent.     

c-fms blockade reverses glomerular macrophage infiltration and halts development of crescentic anti-GBM glomerulonephritis in the rat

Depletion and adoptive transfer studies have demonstrated that macrophages induce glomerular lesions in experimental anti-glomerular basement membrane (anti-GBM) glomerulonephritis. However, there is no current therapeutic strategy that can rapidly and selectively remove these cells from the glomerulus in order to halt disease development. This study examined whether inhibition of the receptor for macrophage colony-stimulating factor (known as c-fms), which is selectively expressed by monocyte/macrophages, can eliminate the macrophage infiltrate in a rat model of crescentic anti-GBM glomerulonephritis. Wistar-Kyoto rats were treated with 10 or 30 mg/kg bid of fms-I (a selective c-fms kinase inhibitor) from the time of anti-GBM serum injection until being killed 1, 5 or 14 days later. fms-I treatment had only a minor effect upon the glomerular macrophage infiltrate on day 1 and did not prevent the subsequent induction of proteinuria. However, fms-I treatment reduced the glomerular macrophage infiltrate by 60% at day 5 and completely reversed the macrophage infiltrate by day 14. In addition, fms-I treatment downregulated the glomerular expression of pro-inflammatory molecules (TNF-α, NOS2, MMP-12, CCL2 and IL-12) on days 1 and 5, suggesting a suppression of the macrophage M1-type response. Despite a significant early loss of glomerular podocytes, ongoing proteinuria and glomerular tuft adhesions to Bowman's capsule, the reversal of the macrophage infiltrate prevented the development of glomerulosclerosis, crescent formation, tubulointerstitial damage and renal dysfunction. In conclusion, this study has identified c-fms kinase inhibition as a selective approach to target infiltrating macrophages in acute glomerular injury, which may have therapeutic potential in rapidly progressive crescentic glomerulonephritis.     

Inhibition of CXCL16 attenuates inflammatory and progressive phases of anti-glomerular basement membrane antibody-associated glomerulonephritis

Chemokines recruit and activate leukocytes during inflammation. CXCL16 is a recently discovered chemokine that is expressed as a transmembrane protein that is cleaved to form the active, soluble chemokine. We analyzed the role of CXCL16 in the development of inflammation and in the progression of the anti-glomerular basement membrane (GBM) antibody-induced experimental glomerulonephritis in Wistar-Kyoto rats. CXCL16 was expressed in glomerular endothelial cells and mediated adhesion of macrophages expressing CXCL16 and its cognate receptor, CXCR6. Glomerular infiltrates displayed a strong migratory response to soluble CXCL16. Soluble CXCL16 and its receptor CXCR6 were induced in nephritic glomeruli throughout the disease, and CXCL16 expression correlated with the up-regulation of ADAM10, suggesting that this disintegrin and metalloproteinase mediates the chemokine activity of CXCL16. Blocking CXCL16 in the acute inflammatory phase or progressive phase of established glomerulonephritis significantly attenuated monocyte/macrophage infiltration and glomerular injury; proteinuria also improved. We conclude that CXCL16/CXCR6 plays a critical role in stimulating leukocyte influx, which causes glomerular damage during anti-GBM glomerulonephritis. Blocking CXCL16 actions limits the progression of anti-GBM glomerulonephritis even when the disease is established.     

老年大鼠肾脏微分离肾小球、肾小管及动脉血管紧张素Ⅱ受体的表达

目的: 观察老年大鼠肾脏不同部位不同亚型的血管紧张素Ⅱ受体(ATR)基因表达的改变。方法: 取3月龄及24月龄雄性Wistar大鼠肾脏,行Western印迹杂交及Northern 印迹杂交检测肾皮质AT₁R的蛋白及基因表达,行冰冻切片(厚5 μm),通过激光切割、弹射微分离系统分离肾小球、肾小管及动脉,提取RNA,利用RT-PCR方法观察AT_1aR mRNA、AT_1bR mRNA及AT₂R mRNA的表达。结果: 24月龄大鼠肾脏的AT₁R在蛋白水平及基因水平均低于3月龄大鼠。应用自动激光微分离技术成功分离了大鼠肾脏的肾小球、肾小管及小动脉。24月龄大鼠肾小球AT_1aR mRNA的表达与3月龄大鼠比较无明显差异,在肾小管表达低于3月龄大鼠,动脉表达高于3月龄大鼠;AT_1bR mRNA在肾小球、肾小管表达均低于3月龄大鼠,在动脉的表达高于3月龄大鼠;AT₂R mRNA的表达在肾小管明显高于3月龄大鼠,在肾小球及动脉的表达无明显差异。结论: 老年大鼠的肾小球、肾小管及肾内动脉各型血管紧张素受体的改变不同,有可能在肾脏增龄性改变中起重要作用。     

Interleukin-10 inhibits experimental mesangial proliferative glomerulonephritis

Conflicting reports exist regarding the effects of interleukin-10 (IL-10) on mesangial cells. There have been reports of both proliferative and antiproliferative effects, and both proinflammatory and anti-inflammatory effects of IL-10 on mesangial cells. However, the potential for IL-10 to affect glomerulonephritis characterized by mesangial proliferation is not known. To test the hypothesis that IL-10 would limit experimental mesangial proliferative glomerulonephritis, IL-10 was administered to rats in which mesangial proliferative glomerulonephritis was induced by administration of anti-Thy 1 antibody. Compared to control treated rats, IL-10 treated rats showed less proliferation, with fewer cells in glomeruli. Glomerular cellular proliferation was reduced, assessed by the numbers of cells within glomeruli expressing either proliferating cell nuclear antigen (PCNA) or bromodeoxyuridine. Glomerular macrophage influx (but not the proportion of glomerular macrophages that were PCNA positive) was reduced by IL-10 administration. There was no significant reduction in glomerular alpha-smooth muscle actin staining. IL-10 treatment resulted in reduced renal IL-1beta mRNA expression and reduced glomerular ICAM-1 expression, but renal expression of MCP-1 and osteopontin mRNA was unaltered. This study demonstrates that in experimental mesangial proliferative glomerulonephritis IL-10 diminishes inflammatory cell recruitment and mesangial cell proliferation. The effects of IL-10 in inhibiting mesangial cell proliferation are likely to be due to a combination of direct effects of IL-10 on mesangial cells and effects mediated by macrophages.     

Isologous monoclonal antibodies can induce anti-GBM glomerulonephritis in rats.

Injection of isologous monoclonal antibodies (SR2, SR3) caused anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM nephritis) in WKY/NCrj rats. The antibodies were obtained from hybridoma cells derived from fusion of the spleen of a nephritic WKY/NCrj rat injected with rat solubilized renal basement membranes with adjuvant, and mouse SP2-myeloma cells. They belonged to the rat IgG2a subclass and bound to rat kidney in a linear pattern along the glomerular and tubular basement membranes. Histological changes in glomeruli were detected at day 1 after the injection; proteinuria with haematuria appeared on day 2; and proteinuria became severe and reached a plateau by day 5. These results demonstrate that anti-GBM nephritis can even be induced by an isologous monoclonal antibody and that the rat IgG2a subclass is at least nephritogenic. The experimental model of anti-GBM nephritis with isologous monoclonal antibodies makes it possible and easier to analyse further the mechanism of anti-GBM nephritis.     

The participation of macrophages, glomerular procoagulant activity, and factor VIII in glomerular fibrin deposition. Studies on anti-GBM antibody-induced glomerulonephritis in rabbits.

The temporal relationships of macrophage accumulation, glomerular fibrin deposition, the expression of glomerular procoagulant activity (PCA), and Factor VIII antigen deposition were studied in rabbits in which antiglomerular basement membrane antibody-induced glomerulonephritis (anti-GBM GN) developed. The initiation of injury coincided with the accumulation of glomerular macrophages. Glomerular fibrin, assessed by immunofluorescence and by deposition of 125I-fibrinogen, paralleled the development of glomerular crescents and renal impairment. Macrophage ingress clearly preceded the deposition of 125I-fibrinogen within glomeruli. Augmented levels of PCA were present in glomeruli prior to the initiation of fibrin deposition, and peak levels coincided with the peak glomerular macrophage presence. Factor VIII related antigen was apparent late in the disease and was present mainly at the margins of fibrinous crescents. These data demonstrate that accumulation of glomerular macrophages precedes glomerular fibrin deposition in anti-GBM GN. The augmentation of PCA, coincident with the appearance of glomerular macrophages, suggests a role for macrophage PCA in the initiation of fibrin deposition within the glomerular tuft in this model.     

De Novo renal expression of macrophage migration inhibitory factor during the development of rat crescentic glomerulonephritis.

Macrophage migration inhibitory factor (MIF), a key mediator of the delayed-type hypersensitivity response, was originally thought to be produced by activated T cells. However, recent studies have found that MIF is produced in many cell types including monocytes/macrophages and anterior pituitary cells. The current study has examined MIF expression in normal and diseased kidney using in situ hybridization, immunohistochemistry, and Northern blotting. MIF mRNA and protein are constitutively expressed in normal kidney, being largely restricted to tubular epithelial cells and some glomerular visceral and parietal epithelial cells. During the development of rat anti-glomerular basement membrane glomerulonephritis, a model of macrophage-mediated renal injury, there was marked de novo expression of MIF by intrinsic kidney cells including endothelium and glomerular and tubular epithelial cells. Up-regulation of MIF expression correlated with macrophage accumulation within the glomerulus (P < 0.001) and tubulointerstitium (P < 0.001). Of significance, the accumulation of macrophages was exclusively localized to areas of strong MIF expression, contributing to focal glomerular and tubulointerstitial lesion formation. In addition, up-regulation of MIF expression by parietal epithelial cells was associated with macrophage accumulation within Bowman's space and crescent formation. Combined in situ hybridization and immunostaining also demonstrated MIF expression by macrophages, T cells, and fibroblast-like cells within renal lesions. In conclusion, these data provide the first demonstration that renal epithelial cells are a major source of MIF in both normal and diseased kidney. Furthermore, the up-regulation of MIF expression may play an important role in macrophage accumulation and progressive renal injury in rat crescentic glomerulonephritis.     

Fc receptor-mediated accumulation of macrophages in crescentic glomerulonephritis induced by anti-glomerular basement membrane antibody administration in WKY rats

Anti-glomerular basement membrane (GBM) glomerulonephritis induced in WKY rats is characterized by glomerular accumulation of CD8(+) T cells and monocytes/macrophages, followed by crescent formation. The mechanism of leukocyte accumulation after antibody binding to GBM is still unclear. To unveil an involvement of Fcgamma receptors (FcgammaR) in leukocytes recruitment we examined the expression of FcgammaR in glomeruli and the effects of the administration of F(ab')(2) fragment of anti-GBM antibody or FcgammaR blocking on the initiation and progression of this model. A gradual increase of FcgammaR mRNA expression in glomeruli during the time course of disease suggested their significance in the development of glomerulonephritis. Glomerular lesions and proteinuria were induced only in rats injected with intact IgG of anti-GBM antibody, but not with the F(ab')(2) fragment. In vivo blocking of FcgammaR by administering heat-aggregated IgG led to the decrease of mRNA expression for all types of FcgammaR (types 1, 2 and 3) and a significant amelioration of glomerulonephritis manifestations. By flow cytometry and immunohistochemistry FcgammaR2-expressing cells in glomeruli were identified as macrophages, but not CD8(+) T cells. The expression of FcgammaR1 and 3 was significantly decreased, and that of FcgammaR2 became undetectable in CD8(+) T cell-depleted rats. Thus, CD8(+) T cells may stimulate FcgammaR expression on macrophages, contributing to their glomerular accumulation and injury. These studies provide direct evidence for a crucial involvement of IgG Fc-FcgammaR interaction in glomerular recruitment of macrophages and following induction of anti-GBM glomerulonephritis in WKY rats.     

Glomerular expression of interleukin-1 receptor antagonist and interleukin-1 beta genes in antibody-mediated glomerulonephritis.

Interleukin-1 (IL-1) is a powerful proinflammatory cytokine whose function is modulated by a natural IL-1 receptor antagonist (IL-1ra). There are few data about kinetics of in vivo synthesis of IL-1ra at tissue level, except in response to bacterial endotoxin. The purpose of this study was to examine the kinetics of local expression of IL-1ra gene in relation to IL-1 beta gene in a model of anti-glomerular basement membrane antibody-mediated glomerulonephritis. Rats were killed in groups of 5 or 6 at 0, 4, 6, 24, 48, and 96 hours after induction of glomerulonephritis. Messenger RNA for IL-1ra and IL-1 beta was undetectable by Northern blot in normal glomeruli but increased markedly 4 to 6 hours after induction of nephritis. The increase in IL-1ra mRNA was more sustained than that of IL-1 beta mRNA. In situ hybridization showed that IL-1 beta mRNA increased diffusely within glomeruli, while IL-1ra mRNA was expressed more discretely. Expression of these mRNA in noninflamed tissues, spleens and lungs, was different, particularly increase in IL-1ra mRNA was more substantial than that of IL-1 beta. These observations suggest that differential expression of IL-1ra and IL-1 beta might focus inflammation in glomeruli while protecting more distant sites. They also raise the possibility of reducing glomerular injury by therapeutic measures that upregulate glomerular synthesis of IL-1ra while reducing that of IL-1 beta.     

Lack of endothelial nitric-oxide synthase leads to progressive focal renal injury

Because endothelial nitric-oxide synthase (eNOS) is generally considered protective against renal injury, we examined eNOS knockout mice for kidney pathology. In 80% of the adults examined, the renal surface was marked by distinct indented scars containing crowded small glomeruli but lacking attached tubules. Although vasculature was intact in the scars, Bowman's space was dilated and glomerular tufts were degenerated. The atubular glomeruli were embedded in a dense interstitial matrix composed of cells positive for fibroblast (FSP-1) or macrophage (F4/80) markers, degenerated proximal tubules and collecting ducts, and diffuse fibrotic deposits. Surrounding regions of kidney contained mostly normal-appearing tubules, but enlarged or sclerotic glomeruli were also present. In neonatal animals, apoptosis and necrosis were concentrated in tubules within focal parenchymal zones, with narrowing of the glomerulotubular "neck." In summary, targeted deletion of eNOS in mice leads to progressive focal renal abnormalities, including glomerular hypoplasia, and tubular cell death, leading to separation of glomeruli from tubules and tubular disruption. These abnormalities begin developing during the normal up-regulation of eNOS in the maturing kidney and are similar to those of a variety of chronic renal disorders. Endogenous renal eNOS production therefore seems critical for the maintenance of nephron maturation and integrity.     

Involvement of neutrophil gelatinase-associated lipocalin and osteopontin in renal tubular regeneration and interstitial fibrosis after cisplatin-induced renal failure

The kidney has a capacity to recover from ischemic or toxic insults that result in cell death, and timely tissue repair of affected renal tubules may arrest progression of injury, leading to regression of injury and paving the way for recovery. To investigate the roles of neutrophil gelatinase-associated lipocalin (NGAL/lcn2) and osteopontin (OPN/spp1) during renal regeneration, the expression patterns of NGAL and OPN in the cisplatin-induced rat renal failure model were examined. NGAL expression was increased from day 1 after injection; it was seen mainly in the completely regenerating proximal tubules of the cortico-medullary junction on days 3–35; however, the expression was not seen in abnormally dilated or atrophied renal tubules surrounded by fibrotic lesions. On the other hand, OPN expression was increased from day 5 and the increased expression developed exclusively in the abnormal renal tubules. NGAL expression level well correlated with the proliferating activity in the regenerating renal epithelial cells, whereas OPN significantly correlated with the α-smooth muscle actin-positive myofibroblast appearance, expression of transforming growth factor (TGF)-β1, and the number of CD68-positive macrophages. Interestingly, rat renal epithelial cell line (NRK-52E) treated with TGF-β1 decreased NGAL expression, but increased OPN expression in a dose-dependent manner. Because increases of TGF-β1, myofibroblasts and macrophages contribute to progressive interstitial renal fibrosis, OPN may be involved in the pathogenesis of fibrosis; on the contrary, NGAL may play a role in tubular regeneration after injury. Expression analysis of NGAL and OPN would be useful to investigate the tubule damage in renal-toxicity.     

Hepatitis C virus RNA and core protein in kidney glomerular and tubular structures isolated with laser capture microdissection

The role of hepatitis C virus (HCV) in the production of renal injury has been extensively investigated, though with conflicting results. Laser capture microdissection (LCM) was performed to isolate and collect glomeruli and tubules from 20 consecutive chronically HCV-infected patients, namely 6 with membranoproliferative glomerulonephritis, 4 with membranous glomerulonephritis, 7 with focal segmental glomerulosclerosis and 3 with IgA-nephropathy. RNA for amplification of specific viral sequences was provided by terminal continuation methodology and compared with the expression profile of HCV core protein. For each case two glomeruli and two tubular structures were microdissected and processed. HCV RNA sequences were demonstrated in 26 (65%) of 40 glomeruli, but in only 4 (10%) of the tubules (P < 0.05). HCV core protein was concomitant with viral sequences in the glomeruli and present in 31 of the 40 tubules. HCV RNA and/or HCV core protein was found in all four disease types. The immunohistochemical picture of HCV core protein was compared with the LCM-based immunoassays of the adjacent tissue sections. Immune deposits were detected in 7 (44%) of 16 biopsy samples shown to be positive by extraction methods. The present study indicates that LCM is a reliable method for measuring both HCV RNA genomic sequences and HCV core protein in kidney functional structures from chronically HCV-infected patients with different glomerulopathies and provides a useful baseline estimate to define the role of HCV in the production of renal injury. The different distribution of HCV RNA and HCV-related proteins may reflect a peculiar 'affinity' of kidney microenvironments for HCV and point to distinct pathways of HCV-related damage in glomeruli and tubules.     

Diagnosis and classification of Goodpasture's disease (anti-GBM)

Goodpasture's disease or anti-glomerular basement membrane disease (anti-GBM-disease) is included among immune complex small vessel vasculitides. The definition of anti-GBM disease is a vasculitis affecting glomerular capillaries, pulmonary capillaries, or both, with GBM deposition of anti-GBM autoantibodies. The disease is a prototype of autoimmune disease, where the patients develop autoantibodies that bind to the basement membranes and activate the classical pathway of the complement system, which start a neutrophil dependent inflammation. The diagnosis of anti-GBM disease relies on the detection of anti-GBM antibodies in conjunction with glomerulonephritis and/or alveolitis. Overt clinical symptoms are most prominent in the glomeruli where the inflammation usually results in a severe rapidly progressive glomerulonephritis. Despite modern treatment less than one third of the patients survive with a preserved kidney function after 6 months follow-up. Frequencies vary from 0.5 to 1 cases per million inhabitants per year and there is a strong genetic linkage to HLA-DRB1¹1501 and DRB1¹1502. Essentially, anti-GBM disease is now a preferred term for what was earlier called Goodpasture's syndrome or Goodpasture's disease; anti-GBM disease is now classified as small vessel vasculitis caused by in situ immune complex formation; the diagnosis relies on the detection of anti-GBM in tissues or circulation in conjunction with alveolar or glomerular disease; therapy is effective only when detected at an early stage, making a high degree of awareness necessary to find these rare cases; 20–35% have anti-GBM and MPO-ANCA simultaneously, which necessitates testing for anti-GBM whenever acute test for ANCA is ordered in patients with renal disease.     

Adhesion molecules in glomerulonephritis

Conclusions The infiltration and activation of leukocytes within the glomerulus and interstitium play a key role in the initiation and progression of glomerulonephritis. The recent characterization of cellular adhesion molecules has led to the identification of mechanisms by which leukocytes enter the kidney and subsequently interact with renal parenchymal cells. The therapeutic goal of intervening in the infiltration and activation of particular leukocyte populations can be approached by strategies that interrupt binding between specific pairs of adhesion molecules. The ability of anti-ICAM-1 antibody administration to intervene in experiment disease models [29, 39, 58] holds promise for treatment of human glomerulonephritis. Indeed, anti-ICAM-1 antibodies have already proven beneficial in human kidney transplantation [32]. There are many possible alternative therapeutic strategies that do not rely upon mAb therapy. One example is the administration of carbohydrate sialyl-Lewis X, a ligand for P-selectin, which suppresses acute neutrophil-dependent lung injury in rats [54]. Another approach is to block cytokines and other soluble mediators which, amongst other functions, stimulate up-regulation of adhesion molecule expression and leukocyte adhesion. Blockade of PAF action through use of specific antagonists has been shown to reduce injury in various experimental models and part of this effect can be attributed to inhibiting firm adhesion of PMNL to endothelium. Treatment with the IL-1 receptor antagonist can suppress progressive crescentic glomerulonephritis in the rat [43], while anti-IL-8 antibody treatment has been reported to prevent neutrophil-mediated acute glomerular injury in experimental immune complex glomerulonephritis [83].In summary, the study of adhesion molecules has greatly increased our understanding of pathogenic mechanisms in glomerulonephritis and it holds tremendous potential for development of novel therapies.     

Macrophage-derived MT1-MMP and increased MMP-2 activity are associated with glomerular damage in crescentic glomerulonephritis

Membrane-type matrix metalloproteinases (MT-MMPs) have been shown to activate pro-MMP-2 on the cell surface and are suggested to be key enzymes in tissue remodelling under various physiological and pathological conditions. To investigate the role of MT-MMP in progressive renal injury, the gene expression and enzymatic activity of MT-MMP were examined in crescentic glomerulonephritis induced by anti-glomerular basement membrane (GBM) antibody in WKY rats. Isolated glomeruli were subjected to RNA and protein extraction 0, 1, 3, 7, 14, and 28 days after intravenous injection of rabbit anti-GBM antibody. Semiquantitative RT-PCR analysis revealed that among the three members of the MT-MMP family, mRNA expression of MT2-MMP remained unchanged and that of MT3-MMP was not observed in glomeruli during the development of nephritis. However, MT1-MMP gene expression increased from day 3 and reached maximum levels at day 7 (5.5+/-0.7-fold increase over day 0), closely associated with macrophage accumulation, crescent formation, and increased proteinuria. Gelatin zymography showed that the active from of MMP-2 emerged from day 7 and remained during the experimental period accompanied by increased proMMP-2, while no active form of MMP-2 was found in control rats. Using an antisense cRNA probe, intense signals of MT1-MMP mRNA were observed mostly in cells within the crescent and in some cells in the mesangial areas. Most of these cells were ED-1-positive macrophages, based on immunostaining of sequential sections. These results suggested that in the MT-MMP family, MT1-MMP was induced in infiltrating macrophages during the development of crescentic glomerulonephritis and possibly contributed to pathological degradation of glomerular extracellular matrices through the activation of proMMP-2.