Epithelial–mesenchymal transition (EMT) of renal tubular cells in canine glomerulonephritis

Tubulo-interstitial fibrosis in dogs may result from primary injury to the interstitium or develop secondary to other renal diseases. As in human renal pathology, tubular epithelial cells (TEC) are believed to actively participate in the mechanisms of renal fibrosis. In this study, we examined the changes in the tubular epithelial component in two specific canine diseases. Immunohistochemistry showed the expression of the epithelial marker cytokeratin, the smooth muscle marker α-SMA, the mesenchymal marker vimentin and PCNA in 20 dogs with membranous glomerulonephritis and membrano-proliferative glomerulonephritis. Results showed that the loss of the epithelial marker in TEC was directly correlated to the grade of tubulo-interstitial disease present and independent of the type of glomerulonephritis. Varying degrees of vimentin positivity were detected in tubular epithelium in areas of inflammation, and low numbers of scattered α-SMA-positive cells were also observed. Immunohistochemistry showed that epithelial tubular cells lose their cytokeratin staining characteristics and transdifferentiate into cells exhibiting key mesenchymal immunophenotypic feature of vimentin-positive staining in both diseases investigated. The integrity of the tubular basement membrane is likely to be fundamental in maintaining the epithelial phenotype of TEC. Animal models provide opportunities for investigating the pathogenesis of renal fibrosis in humans.     

Interacting roles of myofibroblasts,apoptosis and fibrogenic growth factors in the pathogenesis of renal tubulo-interstitial fibrosis

The interrelationship between myofibroblasts and fibrogenic growth factors in the pathogenesis of renal fibrosis is poorly defined. A temporal and spatial analysis of myofibroblasts, their proliferation and death, and presence of transforming growth factor-beta1 (TGF-beta1) and platelet-derived growth factor-B (PDGF-B) was carried out in an established rodent model in which chronic renal scarring and fibrosis occurs after healed renal papillary necrosis (RPN), similar to that seen with analgesic nephropathy. Treated and control groups (N = 6 and 4, respectively) were compared at 2, 4, 8 and 12 weeks. A positive relationship was found between presence of tubulo-interstitial myofibroblasts and development of fibrosis. Apoptotic myofibroblasts were identified in the interstitium and their incidence peaked 2 weeks after treatment. Levels of interstitial cell apoptosis and fibrosis were negatively correlated over time (r = -0.57, p < 0.01), suggesting that as apoptosis progressively failed to limit myofibroblast numbers, fibrosis increased. In comparison with the diminishing apoptosis in the interstitium, the tubular epithelium had progressively increasing levels of apoptosis over time, indicative of developing atrophy of nephrons. TGF-beta1 protein expression had a close spatial and temporal association with fibrosis and myofibroblasts, whilst PDGF-B appeared to have a closer link with populations of other chronic inflammatory cells such as infiltrating lymphocytes. Peritubular myofibroblasts were often seen near apoptotic cells in the tubular epithelium, suggestive of a paracrine toxic effect of factor/s secreted by the myofibroblasts. In vitro, TGF-beta1 was found to be toxic to renal tubular epithelial cells. These findings suggest an interaction between myofibroblasts, their deletion by apoptosis, and the presence of the fibrogenic growth factor TGF-beta1 in renal fibrosis, whereby apoptotic deletion of myofibroblasts could act as a controlling factor in progression of fibrosis.     

实验性肾小管间质纤维化中肾小管上皮细胞表型转化的研究

目的 观察和研究肾小管间质纤维化过程中肾小管上皮细胞发生表型转化的现象及其形态特点。方法 结扎大鼠一侧肾静脉,制作大鼠肾小管间质纤维化模型,连续饲养25d。每5d杀检5只,对肾脏重点检查,未结扎肾静脉的对侧肾作为对照,采用光镜、透射电镜、偏振光显微镜及免疫组织化学方法[链霉素抗生物素蛋白一过氧化物酶(sP)法]观察肾组织的病理变化以及肾小管上皮细胞的表型转化情况。结果肾静脉结扎侧肾逐渐出现肾小管萎缩,肾间质淋巴、单核细胞浸润和纤维化等肾小管间质纤维化的典型病变。免疫组织化学观察发现,随着病变的发展,损伤的肾小管上皮细胞角蛋白表达逐渐减弱,而a平滑肌肌动蛋白、波形蛋白、转化生长因子β1和Ⅰ、Ⅲ型胶原的表达逐渐增强,肾间质中也出现角蛋白阳性的间质细胞。透射电镜下可见肾小管上皮细胞内线粒体减少,内质网和微丝增多,并可见肾小管上皮细胞突破基底膜游离到肾间质中。天狼星红染色偏振光显微镜观察显示早期肾间质中Ⅲ型胶原增生为主,后期以Ⅰ型胶原为主。结论 在大鼠肾小管间质纤维化病变的发生和发展中,肾小管上皮细胞可转化为间质成纤维细胞,是成纤维细胞的来源之一。     

Interacting Roles of Myofibroblasts,Apoptosis and Fibrogenic Growth Factors in the Pathogenesis of Renal Tubulo-interstitial Fibrosis

The interrelationship between myofibroblasts and fibrogenic growth factors in the pathogenesis of renal fibrosis is poorly defined. A temporal and spatial analysis of myofibroblasts, their proliferation and death, and presence of transforming growth factor- &#103 1 (TGF- &#103 1) and platelet-derived growth factor-B (PDGF-B) was carried out in an established rodent model in which chronic renal scarring and fibrosis occurs after healed renal papillary necrosis (RPN), similar to that seen with analgesic nephropathy. Treated and control groups (N =6 and 4, respectively) were compared at 2, 4, 8 and 12 weeks. A positive relationship was found between presence of tubulo-interstitial myofibroblasts and development of fibrosis. Apoptotic myofibroblasts were identified in the interstitium and their incidence peaked 2 weeks after treatment. Levels of interstitial cell apoptosis and fibrosis were negatively correlated over time (r = &#109 0.57, p <0.01 ), suggesting that as apoptosis progressively failed to limit myofibroblast numbers, fibrosis increased. In comparison with the diminishing apoptosis in the interstitium, the tubular epithelium had progressively increasing levels of apoptosis over time, indicative of developing atrophy of nephrons. TGF- &#103 1 protein expression had a close spatial and temporal association with fibrosis and myofibroblasts, whilst PDGF-B appeared to have a closer link with populations of other chronic inflammatory cells such as infiltrating lymphocytes. Peritubular myofibroblasts were often seen near apoptotic cells in the tubular epithelium, suggestive of a paracrine toxic effect of factor/s secreted by the myofibroblasts. In vitro, TGF- &#103 1 was found to be toxic to renal tubular epithelial cells. These findings suggest an interaction between myofibroblasts, their deletion by apoptosis, and the presence of the fibrogenic growth factor TGF- &#103 1 in renal fibrosis, whereby apoptotic deletion of myofibroblasts could act as a controlling factor in progression of fibrosis.     

Involvement of matrix metalloproteinase-2 in the development of renal interstitial fibrosis in mouse obstructive nephropathy

Renal fibrosis is a common finding in progressive renal diseases. Matrix metalloproteinases (MMPs) are involved in epithelial-to-mesenchymal transition (EMT). We investigated the role of MMP-2 and the effect of inhibition of MMPs on the development of renal fibrosis. Renal fibrosis was induced in MMP-2 wild-type (MMP-2?/?) mice by unilateral ureteral obstruction (UUO). Renal histopathology, EMT-associated molecules, and activity of MMP-2 and MMP-9 were examined during the development of interstitial fibrosis. UUO-renal fibrosis was also induced in MMP-2 deficient (MMP-2?/?) and MMP-2?/? mice treated with minocycline (inhibitor of MMPs). In MMP-2?/? mice, MMP-2 and MMP-9 were expressed in damaged tubules, and their activities increased in a time-dependent manner after UUO. Interstitial fibrosis was noted at day 14, with deposition of types III and I collagens and expression of markers of mesenchymal cells (S100A4, vimentin, α-smooth muscle actin, and heat shock protein-47) in damaged tubular epithelial cells, together with F4/80+ macrophage infiltration. Fibrotic kidneys expressed EMT-associated molecules (ILK, TGF-β1, Smad, Wnt, β-catenin, and Snail). In contrast, the kidneys of MMP-2?/? mice and minocycline-treated MMP-2?/? mice showed amelioration of renal fibrosis with reduced expression of markers of mesenchymal cells in tubular epithelial cells, inhibition of upregulated EMT-associated molecules, and suppression of macrophage infiltration. The results suggested that MMP-2 have a pathogenic role in renal interstitial fibrosis, possibly through the induction of EMT and macrophage infiltration. Inhibition of MMPs may be beneficial therapeutically in renal fibrosis.     

肾小管损伤内皮素1,肿瘤坏死因子α的表达及其对离体肾间质成 …

目的 研究内皮素１、肿瘤坏死因子在肾这上皮细胞的表达、肾小管的损伤及它们对肾间质成纤维细胞的影响。方法 应用肾小管上皮细胞及肾间质成纤维细胞的体外培养;建立肾小管损伤动物模型;应用逆转录－聚合酶链反应、免疫组化ＳＰ法染色、放射免疫测定及双重免疫组织化学染色技术,并测定＾３Ｈ－ＴＤＲ掺入率。结果 肾小管上皮细胞既有ＥＴ－１ ｍＲＮＡ和ＴＮＦα ｍＲＮＡ的表达,还有ＥＴ－１及ＴＮＦ－α的蛋白合成及分泌     

Dog as model for down-expression of E-cadherin and β-catenin in tubular epithelial cells in renal fibrosis

Mechanism of renal fibrosis leading to end stage kidney remains still a challenge of interest in humans. The pathogenesis of chronic kidney disease is characterized by progressive loss of kidney function and fibrosis. The mechanism of epithelial–mesenchymal transition (EMT) has been predominantly studied in in vitro studies, and we previously demonstrated the EMT of tubular epithelial cells in dogs. In this study, we examined and quantified the modifications of cadherin–catenin complex by immunohistochemistry of E-cadherin and β-catenin and the mesenchymal marker vimentin in 25 dogs with three different spontaneous inflammatory renal diseases. Results showed a significant down-expression of levels of E-cadherin and β-catenin directly correlated with the tubular–interstitial damage (TID). In TID grades 2 and 3, E-cadherin expression was significantly reduced (p < 0.001). β-catenin expression was overall similar to E-cadherin. The mesenchymal-associated protein, vimentin, was de novo identified in tubules within areas of inflammation. In this work, we identified the loss of cadherin or catenin expression as a progressive mechanism in tubulo-interstitial fibrosis, which allows dissociation of structural integrity of renal epithelia and loss of epithelial polarity. The dog might result more significant as model for new therapies.     

Alkaptonuria and renal failure: a case report and review of the literature.

In alkaptonuric ochronosis, the absence of homogentisic acid oxidase results in the accumulation of homogentisic acid in the body. Associated renal failure is rare and usually occurs in the later stages of the disease. We report a 19-yr-old girl who presented initially with severe renal failure, without family or past history of illness. There was no significant proteinuria or hematuria. No clinical evidence of pigmentation such as skin and subcutaneous cartilages was noted. However, pigment deposits were identified in the renal biopsy specimens obtained within a week after admission and another after a month. Two months later the peritoneal dialysis fluid and skin progressively darkened, suggesting ochronosis. This was confirmed by the detection of homogentisic acid in the serum and urine. The patient expired in renal failure. Renal biopsy tissues showed diffuse chronic tubulo-interstitial disease characterized by widespread tubular atrophy, interstitial fibrosis, and a moderate degree of inflammation. Many tubular cells contained brown, coarsely granular ochronotic pigment (OP) and a few pigment casts were in the lumina. Similar deposits were also in the interstitium and within histiocytes. Ultrastructural studies of the glomeruli revealed small sparse OP deposits in the visceral and parietal epithelial cells, mesangial cells, and rare extracellular and basement membrane deposits. The tubulointerstitial changes were varied: atrophy and dilatation of tubules, varying degrees of lysosomal OP and degeneration of tubular cells, casts containing OP with crystalline material, histiocytes distended with OP, and free interstitial pigment deposition.(ABSTRACT TRUNCATED AT 250 WORDS)     

S100A8/A9 promotes parenchymal damage and renal fibrosis in obstructive nephropathy

Despite advances in our understanding of the mechanisms underlying the progression of chronic kidney disease and the development of fibrosis, only limited efficacious therapies exist. The calcium binding protein S100A8/A9 is a damage‐associated molecular pattern which can activate Toll‐like receptor (TLR)‐4 or receptor for advanced glycation end‐products (RAGE). Activation of these receptors is involved in the progression of renal fibrosis; however, the role of S100A8/A9 herein remains unknown. Therefore, we analysed S100A8/A9 expression in patients and mice with obstructive nephropathy and subjected wild‐type and S100A9 knock‐out mice lacking the heterodimer S100A8/A9 to unilateral ureteral obstruction (UUO). We found profound S100A8/A9 expression in granulocytes that infiltrated human and murine kidney, together with enhanced renal expression over time, following UUO. S100A9 KO mice were protected from UUO‐induced renal fibrosis, independently of leucocyte infiltration and inflammation. Loss of S100A8/A9 protected tubular epithelial cells from UUO‐induced apoptosis and critical epithelial–mesenchymal transition steps. In‐vitro studies revealed S100A8/A9 as a novel mediator of epithelial cell injury through loss of cell polarity, cell cycle arrest and subsequent cell death. In conclusion, we demonstrate that S100A8/A9 mediates renal damage and fibrosis, presumably through loss of tubular epithelial cell contacts and irreversible damage. Suppression of S100A8/A9 could be a therapeutic strategy to halt renal fibrosis in patients with chronic kidney disease.     

Nitric oxide is an important mediator of renal tubular epithelial cell death in vitro and in murine experimental hydronephrosis

Macrophages play a pivotal role in tissue injury and fibrosis during renal inflammation. Although macrophages may induce apoptosis of renal tubular epithelial cells, the mechanisms involved are unclear. We used a microscopically quantifiable co-culture assay to dissect the cytotoxic interaction between murine bone marrow-derived macrophages and Madin-Darby canine kidney cells and primary murine renal tubular epithelial cells. The induction of tubular cell apoptosis by cytokine-activated macrophages was reduced by inhibitors of nitric oxide synthase whereas tubular cell proliferation was unaffected. Furthermore, cytokine-activated macrophages derived from mice targeted for the deletion of inducible nitric oxide synthase were noncytotoxic. We then examined the role of nitric oxide in vivo by inhibiting inducible nitric oxide synthase in the model of murine experimental hydronephrosis. l-N(6)-(1-iminoethyl)-lysine was administered in the drinking water between days 5 and 7 after ureteric obstruction. Macrophage infiltration was comparable between groups, but treatment significantly inhibited tubular cell apoptosis at day 7. Tubular cell proliferation was unaffected. Inducible nitric oxide synthase blockade also reduced interstitial cell apoptosis and increased collagen III deposition. These data indicate that nitric oxide is a key mediator of macrophage-directed tubular cell apoptosis in vitro and in vivo and also modulates tubulointerstitial fibrosis.     

Morphometric analysis of the glomerular capillary area--a comparison of minimal change nephrotic syndrome, focal glomerular sclerosis, and pre-eclampsia.

A morphometric analysis was performed to compare the capillary area in non-sclerotic glomeruli in focal glomerular sclerosis (FGS), pre-eclampsia with focal sclerotic change of the glomeruli, and minimal change nephrotic syndrome (MCNS). The mean and standard deviation of the capillary area was greater in FGS than in pre-eclampsia and MCNS. Tubulo-interstitial lesions, such as tubular atrophy, interstitial fibrosis, and lymphocytic infiltration, were more severe in FGS than in pre-eclampsia. The presence of tubulo-interstitial changes including tubular atrophy and interstitial fibrosis with lymphocytic infiltration is thought to be an important prognostic factor in pre-eclampsia as well as in FGS. Unequal dilatation of the glomerular capillaries in non-sclerotic glomeruli may be harmful to the glomeruli and may lead to the development of glomerular sclerosis.     

肾小管上皮间充质转化与肾脏纤维化

 [摘要] 在肾脏损伤过程中,多种因子可诱导上皮细胞转化为成纤维细胞/肌成纤维细胞,引起肾小管缺失与细胞外基质蛋白沉积,这一过程被称为上皮间充质转化(epithelial-mesenchymal transition, EMT)。在肾脏损伤或应激时,肾小管上皮细胞发生EMT,对肾脏纤维化具有重要作用。肾小管上皮细胞微环境存在多种调节因子,调控EMT相关信号如TGF-β/Smad、Wnt/β-catenin等的表达与传导。本文就近年来肾小管上皮细胞EMT在肾脏纤维化的作用及机制研究进展进行综述。     

IKKα aggravates renal fibrogenesis by positively regulating the Wnt/β-catenin pathway

AKI (acute kidney injury) with maladaptive repair plays exacerbated role in renal fibrosis characterized by tubulointerstitial fibrosis. Previously, we reported that IKKα contributed to kidney regeneration and inhibited inflammation. Here, we first identified the role and mechanism of IKKα on TGF-β1-induced fibrosis in human tubular epithelial cells and fibrotic kidneys. IKKα was up-regulated in kidney tubular epithelium in unilateral ureteral obstruction (UUO) and unilateral ischemic reperfusion injury (UIRI) mice. Immunohistochemical staining showed that IKKα was positively correlated with the extent of kidney fibrosis in tissue biopsies from chronic kidney disease (CKD) patients. Compared with wild-type controls, Ksp-IKKα^−/− mice exhibited inactivated Wnt/β-catenin pathway, decreased serum creatinine and interstitial fibrosis in the kidney after IRI. In TGF-β1-stimulated human tubular epithelial cells, IKKα overexpression enhanced β-catenin nuclear translocation. Blocking IKKα by siRNA specifically suppressed β-catenin activation and downstream profibrotic genes such as fibronectin and α-smooth muscle actin (α-SMA). Taken together, our study demonstrated that IKKα aggravated renal fibrogenesis by activating Wnt/β-catenin signalling pathway, providing a new target for the treatment of kidney fibrosis.     

Role of atrophic tubules in development of interstitial fibrosis in microembolism-induced renal failure in rat

We explored the origin and participation of atrophic tubules in the progression of interstitial fibrosis using a new microembolic rat model of chronic renal failure in which foci of atrophic tubules with cuff-like basement membrane thickening developed at 4 weeks. Atrophic tubules, immunoreactive for vimentin and platelet-derived growth factor, were surrounded by transformed interstitial cells expressing platelet-derived growth factor receptor beta and alpha-smooth muscle actin. Some tubules in the deep cortex and the outer stripe of the outer medulla had a mosaic appearance. Tall, intact proximal tubular cells with a brush border and positivity for Phaseolus vulgaris erythroagglutinin, adjoined typical atrophic tubule cells having no brush border and an immunostaining pattern characteristic for atrophic tubules. The transformed interstitial cells expressing alpha-smooth muscle actin were located near atrophic but not intact tubular epithelial cells. Type IV collagen accumulated between damaged tubular cells and transformed interstitial cells. Heat shock protein 47 showed immunoreactivity in damaged epithelial cells and in interstitial myofibroblasts. Staining with an anti-endothelial antibody suggested damage to peritubular capillaries near atrophic tubules. By disturbance of microcirculation following microsphere injection, proximal tubular cells expressed vimentin and platelet-derived growth factor; diffusion of the latter presumably stimulated transformation of interstitial cells to myofibroblasts. Injured tubular epithelial cells and interstitial myofibroblasts both were responsible for interstitial fibrosis.     

The role of cell plasticity in progression and reversal of renal fibrosis

The need for novel insights into the mechanisms of progression of renal disease has become urgent during the last several years because of the increasing incidence of chronic renal disease worldwide. Independent of the underlying disease, the subsequent progression of renal fibrosis is characterized mainly by both an exaggerated synthesis and abnormal accumulation of extracellular matrix proteins produced by mesenchymal cells within the kidney. These cells are mainly myofibroblasts deriving from a variety of renal cells such as vascular smooth muscle, mesangial, resident stem, tubular epithelial, vascular endothelial cells or pericytes. The appearance of myofibroblasts is a reversible process, as suggested by studies in experimental models showing regression of renal fibrosis during therapy with antagonists and/or blockers of the renin-angiotensin system. An additional factor that can also affect the mechanisms of progression/regression of fibrosis is the plasticity of podocytes controlling glomerular filtration.     

Macrophages Regulate Renal Fibrosis Through Modulating TGFβ Superfamily Signaling

Renal fibrosis is the fundamental pathway leading to end-stage renal disease, while its exact molecular basis remains incompletely elucidated. Previous studies have demonstrated that transforming growth factor beta 1 (TGFβ1) is an inducer of the epithelial-to-mesenchymal transition (EMT) of renal tubular epithelial cells, while bone morphogenic protein 7 (BMP7) counteracts TGFβ1-induced EMT and reverses chronic renal injury. Although macrophage recruitment is believed to play an important role during the whole pathogenesis, the mechanism underlying their activate involvement in the formation of renal fibrosis besides phagocytosizing extracellular matrix and apoptotic cells is largely unknown. Here, in a mouse unilateral ureteral obstruction (UUO) model, we show that the recruited macrophages are mainly M1 macrophages at early stage. However, these F4/80-positive and CD301-negative M1 macrophages were shortly polarized into F4/80-positive and CD301-positive M2 macrophages, respectively, which released high levels TGFβ1, to contradict the local expression of BMP7 to facilitate EMT-induced renal fibrosis. M2 macrophages depletion specifically inhibited EMT, and subsequently the renal fibrosis. Adoptive transplantation of M2 macrophages increased the features of renal fibrosis. Our study thus identified double-edged effects of macrophages in the formation of renal fibrosis, which suggest that modulation of macrophage polarization may substantially improve the treatment of renal fibrosis.     

转化生长因子β1抑制人肾小管上皮细胞的增殖

背景：慢性肾衰竭进展过程中的一个重要病理改变是炎症和纤维化,主要包括肾小球和肾小管的炎症和纤维化。目前大多数研究主要集中于肾小球,对于肾小管病变的研究相对较少。但实际上部分疾病的肾小管病变出现在肾小球病变之前,其对于疾病预后更具有指导意义。 目的：观察转化生长因子β1对人类肾小管上皮细胞HK-2增殖的影响,探索转化生长因子β1在肾小管炎症和纤维化方面的作用。 方法：将传代培养的HK-2细胞分成空白对照组和转化生长因子β1作用组,分别使用DMEM/F12培养液,以及含转化生长因子β1(2,5,10 μg/L)的DMEM/F12培养液培养,在倒置显微镜下观察各组细胞形态的改变,并使用MTT法检测细胞增殖情况。 结果与结论：转化生长因子β1能显著抑制人肾小管上皮细胞的增殖,并促使细胞向纤维样改变,与空白对照组相比差异有显著性意义(P < 0.05),其抑制增殖作用并不随转化生长因子β1质量浓度的增大而显著增强,作用时间可持续至72 h。结果可见转化生长因子β1能够抑制人肾小管上皮细胞的增殖,并具有促进肾间质纤维化的作用。     

Dissection of key events in tubular epithelial to myofibroblast transition and its implications in renal interstitial fibrosis

Myofibroblast activation is a key event playing a critical role in the progression of chronic renal disease. Emerging evidence suggests that myofibroblasts can derive from tubular epithelial cells by an epithelial to mesenchymal transition (EMT); however, the details regarding the conversion between these two cell types are poorly understood. Here we dissect the key events during the process of EMT induced by transforming growth factor-beta1. Incubation of human tubular epithelial cells with transforming growth factor-beta1 induced de novo expression of alpha-smooth muscle actin, loss of epithelial marker E-cadherin, transformation of myofibroblastic morphology, and production of interstitial matrix. Time-course studies revealed that loss of E-cadherin was an early event that preceded other alterations during EMT. The transformed cells secreted a large amount of matrix metalloproteinase-2 that specifically degraded tubular basement membrane. They also exhibited an enhanced motility and invasive capacity. These alterations in epithelial phenotypes in vitro were essentially recapitulated in a mouse model of renal fibrosis induced by unilateral ureteral obstruction. Hence, these results indicate that tubular epithelial to myofibroblast transition is an orchestrated, highly regulated process involving four key steps including: 1) loss of epithelial cell adhesion, 2) de novo alpha-smooth muscle actin expression and actin reorganization, 3) disruption of tubular basement membrane, and 4) enhanced cell migration and invasion.     

Chronic interstitial nephritis associated with gold therapy

A patient suffered chronic interstitial nephritis after receiving large quantities of gold salts for rheumatoid arthritis. Gold deposits were seen with transmission electron microscopy and confirmed by microprobe x-ray analysis both within renal tubular epithelial cells and interstitial macrophages and free within the renal interstitium. Clinical resolution of renal failure followed discontinuation of therapy with gold salts. Probable mechanisms of injury to renal tubular epithelial cells include uptake of gold by tubular epithelial cells and incorporation of gold into mitochondria, with subsequent cellular injury; interstitial deposits probably occur after necrosis of tubular epithelial cells, with release of gold into the interstitium and resultant inflammation. Thus, chronic interstitial nephritis can be added to the patterns of renal injury seen after gold therapy for rheumatoid arthritis.     

非免疫因素肾病的免疫发病机制

非免疫因素性肾病是指由许多非免疫性因素导致的肾脏损害包括急慢性肾脏局部缺血、蛋白负荷过多、高脂血症、肾大部切除、膀胱输尿管返流、尿路梗阻、多囊肾、糖尿病、年龄老年化、肾盂肾炎、高血压、肾毒性物质（药物和毒物）、血流动力学改变、代谢因素等，此类肾病在临床上越来越常见，是发展成肾间质纤维化的主要因素，其病理变化主要表现为淋巴细胞、巨噬细胞的浸润。发病机制包括RAS系统、ROS系统、免疫发病机制及肾微血管内皮细胞和肾小管上皮细胞损伤导致的免疫活性细胞的浸润及分泌的细胞因子的作用。对于非免疫肾病的治疗主要有：ACEI、ARBs、免疫抑制剂强的松、环磷酰胺、环孢霉素和霉芬酸酯等，研究的热点是共刺激分子。