Tubular and interstitial expression of ICAM-1 as a marker of renal injury in IgA nephropathy

BACKGROUND: The upregulated renal expression of intercellular adhesion molecule 1 (ICAM-1) is associated with glomerular and interstitial infiltration of leukocytes. AIM: To test the hypothesis that renal expression of ICAM-1 may be predictive in the highly variable IgA nephropathy (IgAN). METHODS: ICAM-1 (CD54) in tubular epithelium and interstitial leukocytes, macrophages (CD14), and T cells (CD3) were assessed using avidin-biotin-peroxidase in renal biopsy specimens from 45 patients with IgAN and from 29 patients with no glomerulonephritis. RESULTS: In IgAN, tubular ICAM-1+ was seen in 25 of 45 (55%) biopsy specimens, associated with glomerular hypercellularity, glomerulosclerosis involving less than 50% of the glomerular area, interstitial cellular infiltration, tubular atrophy, and proteinuria (U = 44, p = 0.005). Interstitial ICAM-1+ leukocytes were correlated with glomerulosclerosis involving less and more than 50% of the glomerular area, tubular atrophy, interstitial fibrosis, and serum creatinine concentration (r = 0.6343, p < 0.001). In patients with an increase of 50% in the serum creatinine concentration, interstitial ICAM-1+ leukocytes and CD14+ and CD3+ cells were significantly more numerous than in patients with a stable creatinine concentration. In patients with no glomerulonephritis, tubular ICAM-1+ was seen in 7 of 29 (24%) biopsy specimens, inversely correlated with the number of normal glomeruli and associated with glomerulosclerosis covering more than 50% of the glomerular area, tubular atrophy, and creatinine. CONCLUSIONS: Tubular and interstitial expression of ICAM-1 can be a marker of tubulointerstitial disturbance in IgAN. Interstitial ICAM-1 may be an adverse predictor of disease progression.     

Differences in glomerular leukocyte infiltration between IgA nephropathy and membranoproliferative glomerulonephritis

Background: An important aspect in glomerular nephritic processes is the enhanced influx of leukocytes into the glomerulus. Methods: To investigate the mechanisms of intraglomerular leukocyte infiltration in IgA nephropathy (IgA-N) and membranoproliferative glomerulonephritis type I (MPGN-I), we immunohistochemically examined the intraglomerular expression of leukocyte function-associated antigen-1 (LFA-1, CD11a/CD18), macrophage-1 (Mac-1, CD11b/CD18) and intercellular adhesion molecule-1 (ICAM-1, CD54) together with glomerular deposition of C3c and fibrinogen. Results: In IgA-N (n=42), LFA-1⁺ cells were distributed mainly in glomeruli with intense expression of ICAM-1, and there was a positive correlation (P<0.001) between the number of LFA-1⁺ cells and the degree of ICAM-1 expression. Mac-1⁺ cells had no correlation with glomerular C3c deposition, but had a significant correlation with fibrinogen deposition (P<0.05). The number of LFA-1⁺ cells was significantly greater than of Mac-1⁺ cells (P<0.05). The number of LFA-1⁺ cells was strongly correlated with that of CD68⁺ cells (P<0.00001). In MPGN-I (n=43), on the contrary, Mac-1⁺ cells correlated only with C3c deposition (P<0.001), and they were observed mainly in peripheral loops of glomerular capillaries where C3c was deposited with a similar distribution. However, there was no relationship between LFA-1⁺ cells and ICAM-1 expression. The number of Mac-1⁺ cells was greater than that of LFA-1⁺ cells (P<0.0001), and most Mac-1⁺ cells were identical to CD15⁺ cells. Conclusion: These results indicate the possibility that different mechanisms may cause glomerular leukocyte infiltration in various forms of human glomerulonephritis. The LFA-1/ICCAM-1 pathway may play an important role in glomerular leukocyte infiltration in IgA-N, while the Mac-1/complement pathway may be important in MPGN-I. The former may promote mainly the infiltration of CD68⁺ cells, and the latter may promote that of CD15⁺ cells. In addition, Mac-1⁺ cells may act as fibrinogen and complement receptors in IgA-N and MPGN-I, respectively. Key words: adhesion molecules; complements; glomerular leukocytes infiltration; IgA nephropathy; membranoproliferative glomerulonephritis      

Role of β2 integrins in glomerular leucocytes in Henoch-Schoenlein purpura nephritis: an age-matched comparative study with immunoglobulin A nephropathy

SUMMARY: A comparative immunohistological study was performed for the glomerular deposition of complements (C1q and C3c), fibrin/fibrinogen‐related antigen (FRA), the expression of intercellular adhesion molecule‐1 (ICAM‐1), and the infiltration of leucocytes bearing β₂ integrins (leucocyte function associated antigen‐1 (LFA‐1), complement receptor 3 (CR3) and complement receptor 4 (CR4)) on renal biopsy specimens from 49 cases with Henoch‐Schoenlein purpura nephritis (HSPN), and 49 age‐matched cases with immunoglobulin A nephropathy (IgAN). the glomerular expression of ICAM‐1 was signifcantly correlated with the glomerular infiltration of leucocyte function associated antigen (LFA)‐1⁺ leucocytes in both diseases, and with that of CR3⁺ leucocytes in HSPN. the expression of ICAM‐1 was closely localized with the infiltration of LFA‐1⁺ leucocytes in the study with double immunostaining. the incidence and intensity of glomerular deposition of FRA were significantly higher in HSPN than in IgAN (P< 0.001), and those of C3c were significantly lower in HSPN than in IgAN (P< 0.001). the glomerular deposition of FRA was significantly correlated with the glomerular infiltration of CR4⁺ leucocytes in HSPN (P<0.05) but not in IgAN. In contrast, the glomerular deposition of C3c was significantly correlated with the glomerular infiltration of CR4⁺ leucocytes in IgAN (P<0.05), but not in HSPN. Studies with double immunostaining revealed a close association of CR4⁺ leucocytes with FRA deposition in HSPN and with C3c deposition in IgAN, respectively. the number of glomerular leucocytes bearing β₂ integrins was significantly correlated with urinary protein at the time of renal biopsy in both diseases. These results suggested the differential roles of β₂ integrins in the induction of glomerular injury in HSPN and IgAN. the ICAM‐1/LFA‐1 interaction may commonly be involved in the glomerular infiltration of leucocytes in both diseases. the ICAM‐1/CR3 interaction may be involved only in HSPN. Complement receptor 4 may function as a fibrin/fibrinogen receptor in HSPN, while CR4 may function as a complement receptor in IgAN.     

Intercellular adhesion molecule-1 and tumour necrosis factor-α expression in human glomerulonephritis

Summary: The relationship between renal expression of intercellular adhesion molecule-1 (ICAM-1), glomerular hypercellularity, renal function and renal tumour necrosis factor-α (TNF-α) expression was examined by immunohistochemistry staining in 64 cases of human glomerulonephritis. Glomerular anti-ICAM-1 antibody staining was increased in most cases of IgA nephropathy and lupus nephritis, but was unchanged compared to normal in membranous nephropathy and minimal change disease, and reduced in glomerular sclerosis. However, when taken together, patients with mild or no glomerular hypercellularity (group A) showed normal ICAM-1 expression, those with moderate to severe hypercellularity (group B) had increased glomerular ICAM-1 expression (P<0.001), while those with glomerular sclerosis (group C) had reduced glomerular ICAM-1 expression. Patients in groups B and C also showed a significant increase in tubular ICAM-1 expression (P<0.01) and interstitial infiltration of ICAM-1 ⁺ cells (P<0.001). Indeed, tubular ICAM-1 expression correlated with decreased creatinine clearance (r= -0.352; P<0.05). In situ hybridization demonstrated that increase in tubular ICAM-1 staining was due to de novo gene expression, rather than absorption of soluble ICAM-1 from the lumen. Focal expression of tumour necrosis factor-α was seen in areas of leucocyte infiltration and strong ICAM-1 expression. Indeed, TNF-α staining correlated with increased renal ICAM-1 expression in both glomerular and tubulointerstitial compartments (r=0.81; P<0.01). to confirm that TNF-α can directly stimulate renal ICAM-1 expression, TNF-α was shown to transiently increase ICAM-1 mRNA synthesis for 4-8 h and cause a progressive increase in ICAM-1 protein on the surface of cultured human mesangial cells. In summary; (i) increased glomerular ICAM-1 expression was restricted to cases of moderate to severe hypercellularity; (ii) tubular ICAM-1 expression correlated with both creatinine clearance and interstitial infiltration of ICAM-1⁺ cells; and (iii) TNF-α expression was shown to correlate with the degree of renal ICAM-1 expression, suggesting that local TNF-α plays an important role in the up-regulation of ICAM-1 in human glomerulonephritis.     

Glomerular CD8+ cells predict progression of childhood IgA nephropathy

The aim of this study was to evaluate whether the infiltrating T-lymphocyte can be a predictor in the disease progression of IgA nephropathy (IgAN). Twenty children with IgAN, followed for more than 5 years, were divided into progressive (n=5) and non-progressive groups (n=15). We assessed glomerular and interstitial infiltration of T-lymphocytes (CD4⁺ and CD8⁺ cells) and expression of α-smooth muscle actin (α-SMA) and transforming growth factor- β (TGF- β) using an indirect immunofluorescence method on the renal biopsies. We analyzed their relationship to the degree of proteinuria, histological changes, and prognosis. The number of CD8⁺ cells in glomeruli and in interstitium was higher in the progressive group than in the non-progressive group. The glomerular α-SMA staining was more intensive in the progressive group than in the non-progressive group. Urinary protein and the degree of histological changes were also higher in the progressive group than in the non-progressive group. Among these markers, the number of glomerular CD8⁺ cells was the most apparent difference between the two groups. In conclusion, these results indicate that the number of glomerular CD8⁺ cells is the most sensitive predictor of disease progression in childhood IgAN. Received: 20 June 2000 / Revised: 7 February 2001 / Accepted: 8 February 2001     

人类IgA肾病间质小管中炎性细胞的研究

目的探讨人类IgA肾病(IgAN)间质小管中炎性细胞(CD4+、CD8+、CD25+、MAC387+、27E10+)与临床肾功能以及病理的关系。方法对36例IgAN患者肾组织石蜡切片行PAS染色及免疫组化染色(CD4、CD8、CD25、MAC387、27E10),利用电子图像分析系统测量间质小管面积(mm2),计算单位面积间质小管中炎性细胞数目。结合病理指数(肾小球硬化,肾小管萎缩,间质纤维化程度)及肾活检前后肾功能,用SPSS软件包进行统计学分析。结果在肾间质小管中,CD4+、CD8+细胞均与间质纤维化呈正相关(r=0.38、0.37,P均<0.05):CD8+细胞与肾小球硬化相关(r=0.40,P<0.05)。间质CD4+、CD8+以及MAC387+细胞数均与肾活检前Scr呈正相关(r=0.37、0.39、0.36,P均<0.05)。多元逐步回归分析显示,CD8+以及MAC387+细胞数是预测肾功能的主要相关因素。4例ESRD患者27E10+细胞数明显多于非ESRD患者组。结论浸润于间质小管中的CD4+、CD8+、MAC387+在IgAN的肾功能和肾组织损伤中可能发挥重要作用。CD8+、MAC387+细胞数是影响IgAN预后的独立因素。间质27E10+细胞可能是预测IgAN进展的有效因子。     

Myofibroblasts and the progression of crescentic glomerulonephritis

Background: The cellular and humoral factors involved in the pathogenesis of glomerulosclerosis and renal fibrosis following a crescentic glomerulonephritis have not been fully elucidated. Myofibroblasts and transforming growth factor-{beta} (TGF-{beta}) have been implicated in the development of experimental and clinical renal fibrosis. We have attempted to identify these mediators in crescentic glomerulonephritis and determine their role in the progression of the disease. Patients and methods. We have studied retrospectively 21 patients with crescentic and necrotizing glomerulonephritis (CNG) with emphasis on the renal expression (detected by immunohistochemistry) of myofibroblasts (&agr;-smooth muscle actin⁺ cells), TGF-{beta} and collagen (III and IV) as well as their relationship with the clinical outcome of these patients. In situ hybridization histochemistry was applied to determine the site of synthesis of TGF-{beta}1 and collagen III. All the patients were treated by immunosuppression and followed up for a median period of 14 months. Results: Myofibroblasts and TGF-{beta} were detected in the crescents as well as in the periglomerular and tubulointerstitial areas in CNG biopsies. TGF-{beta}1 was also detected within renal tubular cells. The percentage of glomeruli with fibrotic and fibrocellular crescents was positively correlated with the severity of Bowman's capsule disruption (r-0.631, P<0.01) and with the intensity of myofibroblast expression in the interstitium (r-0.504, P<0.05). Strong interstitial immunostain for myofibroblasts and TGF-{beta} was also noted in association with interstitial fibrosis. In situ hybridization revealed the site of synthesis of TGF-{beta}1 to be the renal tubular cells of patients with CNG. By contrast, the site of synthesis of collagen III appeared to be confined to interstitial cells surrounding vessels, tubules and the glomeruli in a distribution identical to that of myofibroblasts. There was a significant positive correlation between the number of interstitial &agr;-SMA⁺ cells and both interstitial TGF-{beta} (r=0.591, P<0.01) and interstitial collagen IV (r=0.588, P<0.01). In addition, the number of interstitial &agr;-SMA⁺ cells and the extent of immunostain for collagen IV were positively correlated with the final serum creatinine (r=0.517, P<0.05 and r=0.612, P<0.01 respectively) and partially predicted functional outcome (R²=26.7% and 37.5% respectively) as well as the response to treatment. An association was observed between periglomerular myofibroblasts and the generation of fibrotin and fibrocellular crescents. Conclusion: These observations suggest a causal link between myofibroblasts and fibrotic crescent formation. We also believe that interstitial myofibroblasts are actively involved in the pathogenesis of interstitial fibrosis in CNG.     

Significance of CD25 Positive Cells and Macrophages in Noncrescentic IgA Nephropathy

The aim of this study was to determine whether infiltration by CD25 positive cells, macrophages, and activated macrophages in the kidney is predictive of chronic histological injury and renal prognosis in adults with noncrescentic IgA nephropathy. Renal biopsies of 36 patients with noncrescentic IgA nephropathy were examined by immunohistochemistry for glomerular and interstitial CD4, CD8, and CD25 positive cells, monocytes/macrophage (Mac387), and activated macrophages (27E10). Renal injury (glomerulosclerosis, mesangial cell hypercellularity, tubular atrophy, and interstitial fibrosis) at the time of biopsy and renal prognosis (follow-up creatinine and creatinine clearance) were assessed. The mean follow-up period was 22.5 ± 16.5 months. The number of interstitial CD8 positive cells was the best predictor of renal injury at the time of biopsy, and was positively correlated with glomerulosclerosis (p = 0.04), tubular atrophy (p = 0.04), and interstitial fibrosis (p = 0.01) but not with mesangial cell hypercellularity. The number of interstitial Mac387 and 27E10 positive cells were the best predictors of renal prognosis (r² = 0.33 and 0.34 respectively, both p < 0.01). These data suggest the presence of CD8 cells and macrophages in the kidney at the time of biopsy could potentially serve as pathological markers to identify patients with IgA nephropathy, which may warrant more aggressive medical therapy.     

VCAM-1, ICAM-1, and E-selectin in IgA nephropathy and Schönlein-Henoch syndrome: differences between tissue expression and serum concentration

The tissue expressions of vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1) and endothelial leukocyte adhesion molecule 1 (E-selectin-1) were investigated in biopsy specimens from 28 patients with different stages of IgA nephropathy (IgAN) and 20 patients with acute renal failure (ARF) or chronic renal diseases (amyloidosis, Alport's glomerulopathy) by immunohistochemistry. The results were compared with the serum levels of the three adhesion molecules. VCAM-1 expression was significantly increased on parietal/tubular epithelial cells in IgAN and ARF. Significantly elevated circulating VCAM-1 levels were measured in IgAN and amyloidosis, but did not correlate with renal function (creatinine clearance). Significantly increased glomerular endothelial/epithelial ICAM-1 expression was found in IgAN and ARF. Intense mesangial ICAM-1 expression was found in mild stages of IgAN and in Sch?nlein-Henoch syndrome. Circulating ICAM-1 was not significantly elevated in IgAN and different renal diseases. VCAM-1 and ICAM-1 expressions of interstitial infiltrating cells were significantly higher in severe than in mild IgAN and associated with an increased infiltration of inflammatory leukocytes. Patients with IgAN and different renal diseases had decreased mesangial and almost absent interstitial E-selectin expression as compared with controls. The circulating E-selectin levels were significantly elevated in ARF. In conclusion, the tissue expression of adhesion molecules in IgAN reflects a continuous inflammatory renal activity. However, only increased circulating VCAM-1 serum levels correlated significantly with the histological state of renal inflammation and could be used as a disease marker.     

Relationship between intermedin and renal interstitial capillary loss in IgA nephropathy patients

Objective To explore the relationship between intermedin (IMD) and renal interstitial capillary loss in IgA nephropathy (IgAN) patients. Methods Renal biopsy specimens collected from primary IgAN patients in our hospital (n=80) were compared with normal renal tissues. Expressions of IMD, CD31 and VE-cadherin were examined by immunohistochemical method, and plasma concentrations of IMD and TGF-β1 in 37 cases from the 80 cases were compared. The relationship between IMD and renal interstitial capillary loss in IgAN patients was analyzed. Results IMD and VE-cadherin in renal tubule interstitium expressions increased compared to the control group at the early stage of IgAN (P＜0.05). CD31 expression remained unchanged at the early stage of pathological lesions of IgAN (P＞0.05), but decreased at the early stage of clinical stage of IgAN compared to the control (P＜0.05). Expressions of IMD, CD31 and VE-cadherin were reducing as the disease progressed, and the correlations of CD31 and VE-cadherin (r=0.517, P＜0.01), IMD and CD31 (r=0.655, P＜0.01) or IMD and VE-cadherin (r=0.576, P＜0.01) were positive. Plasma concentrations of IMD and TGF-β1 were higher than those of the control group at the early stage of IgAN (P＜0.05), and the changes of IMD and TGF-β1were correlated positively (r=0.582, P＜0.01). Conclusion Compared with the control group, expression of IMD in kidney tubules increases at the early stage of IgAN, and change of IMD correlates closely with the renal interstitial capillary loss. Plasma concentrations of IMD and TGF-β1 increase compared with the control group at the early stage of IgAN, and the changes of IMD and TGF-β1 are related closely.     

Additive effect of PPAR-�� agonist and ARB in treatment of experimental IgA nephropathy

Our recent in vitro study demonstrated peroxisome proliferator-activated receptor-γ (PPAR−γ) agonist potentiated the anti-inflammatory effect of angiotensin receptor blocker (ARB) in tubular epithelial cell under milieu mimicking IgA nephropathy (IgAN). Here we studied the therapeutic effect of combining a PPAR-γ agonist, rosiglitazone (Ros), with an ARB, losartan (Los), in experimental IgAN induced in Lewis rats by oral and intravenous immunization with bovine gamma-globulin (BGG). The rats were randomly divided into six groups: control, IgAN, IgAN with unilateral nephrectomy (IgAN/1K), and IgAN/1K receiving Ros, Los, or Ros + Los. Medication was given 1 week after nephrectomy until killing. Rats developing IgAN had hematuria, mesangial hypercellularity with IgA deposition, glomerular damage, and tubulointerstitial infiltration of CD25+ leukocytes accompanied by increased renal expression of TGF-β, AngII receptor subtype-1 (ATR1) and ICAM-1. The renal histopathology, albuminuria, and renal expression of TGF-β, ATR1 and ICAM-1 worsened with unilateral nephrectomy. Ros or Los reduced the renal expression of PCNA, TGF-β, ATR1, and ICAM-1 in IgAN rats with nephrectomy. Despite no difference between rats treated with monotherapy, combined therapy offered additive effect with decreased renal expression of TGF-β, ATR1 and ICAM-1 and attenuation of renal injury. Our animal study suggests combined PPAR-γ agonist and ARB holds promise for future therapy for IgAN.     

Tubular atrophy in the pathogenesis of chronic kidney disease progression

The longstanding focus in chronic kidney disease (CKD) research has been on the glomerulus, which is sensible because this is where glomerular filtration occurs, and a large proportion of progressive CKD is associated with significant glomerular pathology. However, it has been known for decades that tubular atrophy is also a hallmark of CKD and that it is superior to glomerular pathology as a predictor of glomerular filtration rate decline in CKD. Nevertheless, there are vastly fewer studies that investigate the causes of tubular atrophy, and fewer still that identify potential therapeutic targets. The purpose of this review is to discuss plausible mechanisms of tubular atrophy, including tubular epithelial cell apoptosis, cell senescence, peritubular capillary rarefaction and downstream tubule ischemia, oxidative stress, atubular glomeruli, epithelial-to-mesenchymal transition, interstitial inflammation, lipotoxicity and Na⁺/H⁺ exchanger-1 inactivation. Once a a better understanding of tubular atrophy (and interstitial fibrosis) pathophysiology has been obtained, it might then be possible to consider tandem glomerular and tubular therapeutic strategies, in a manner similar to cancer chemotherapy regimens, which employ multiple drugs to simultaneously target different mechanistic pathways.     

Renal interstitial tenascin immunostaining and immune cell infiltration in IgA nephropathy

SUMMARY: Interstitial expression of tenascin and interstitial leucocyte infiltration were examined by an indirect immunoperoxidase method using monoclonal antibodies against tenascin, CD45 (all leucocytes), CD45RO (T cells) and CD68 (monocytes/macrophages) on renal biopsy specimens from 25 patients with mesangial proliferative IgA-positive glomerulonephritis (IgAN). Ten biopsy kidney specimens, which were removed because of renal trauma, were used as the control group. In patients with IgAN, the mean interstitial expression of tenascin was significantly higher than in the control group. Strong tenascin staining was detected in areas with interstitial damage. In patients with IgAN there were positive correlations between the interstitial expression of tenascin and the relative interstitial cortical volume, as well as serum creatinine. In the IgAN patents, a significant increase in the total number of interstitial CD45-immunopositive cells, CD45RO-positive and CD68-positive cells was seen compared with the control group. In patients with IgAN, immunostaining of tenascin did not correlate with the number of T-cells, monocytes/macrophages or all leucocytes in the renal interstitium. These results suggest that in patients with IgAN the interstitial accumulation of tenascin did not depend on the type or the density of interstitial inflammatory infiltrates.     

Up-regulation of ICAM-1 and VCAM-1 expression during macrophage recruitment in lipid induced glomerular injury in ExHC rats

Summary: A number of studies have demonstrated an important role for macrophages (Mo) in lipid induced glomerular injury; however, little is known of the mechanisms which facilitate Mo infiltration in this disease. the present study examined the expression of adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) during the development of glomerular Mo infiltration in ExHC rats; a strain which is susceptible to lipid induced glomerular injury. Twenty-five male 6 week old ExHC rats were placed on a normal diet supplemented with 3% cholesterol, 0.6% sodium cholate and 15% olive oil (high-cholesterol diet, HCD). Groups of five rats were killed prior to the beginning of the HCD or after 3 days, 1, 2 and 6 weeks on a HCD. A group of five matched ExHC rats on a normal diet served as a control. ExHC rats fed a HCD showed marked hypercholesterolaemia in the absence of any increase in plasma triglyceride levels from day 3 (190 ± 14 vs 42 ± 2 mg/dL in control; mean ± s.e.m., P<0.01), and developed mild proteinuria (21.9 ± 2.7 vs 5.2 ± 0.5 mg/24 h in control; P<0.01) and segmental glomerular lesions at week 6. Immunoperoxidase staining identified a significant increase in glomerular ED1⁺Mo at week 1 (2.0 ± 0.2 vs 1.0 ± 0.1 ED1⁺Mo/glomerular cross-section in control, P<0.01) which was further increased at week 6 (6.9 ± 0.4 ED1⁺Mo/gcs). There was also a significant increase in glomerular cells expressing the adhesion molecule ligands lymphocyte function-associated antigen-1 (LFA-1) and very late antigen-4 (VLA-4). Coincident with Mo infiltration, there was an increase in the intensity of glomerular ICAM-1 protein expression as shown by antibody staining. In addition, northern blot analysis of cortical RNA and in situ hybridization demonstrated an increase in glomerular ICAM-1 and VCAM-1 mRNA expression from day 3 onwards. In conclusion, these results suggest that both ICAM-1/LFA-1 and VCAM-1/VLA-4 interactions play an important role in Mo recruitment and accumulation during the development of lipid induced glomerular injury.     

Cellular apoptosis and proliferation in experimental renal fibrosis

Background: The progression of chronic renal failure (CRF) is associated with the progressive deletion of renal cells along with the fibrosis of the kidney. We have studied the role of programmed cell death (apoptosis) in the progression of experimental CRF and renal scarring. Methods: The sub-total (5/6th) nephrectomy (SNx) model of CRF was studied in adult male Wistar rats, with renal tissue collected from experimental and control animals on days 7, 15, 30, 60, 90, and 120 post SNx (n-6 per group). These were examined for morphological signs of apoptosis by light and electron microscopy. Further, we stained the nuclear chromatin by the acridine orange fluorescent method and detected signs of DNA cleavage by endonucleases via the principal of TUNEL staining (ApopTag™). Rates of cellular proliferation were measured simultaneously by immunohistochemical staining for the proliferating cell nuclear antigen (PCNA). In addition, cell division was monitored by counting of morphologically mitotic motifs detectable by light microscopy. Results: Progressive renal insufficiency associated with glomerulosclerosis and tubulointerstitial fibrosis took place in the majority of SNx rats. In these animals, we noted a marked and progressive increase in the number of apoptotic glomerular, tubular as well as interstitial cells. The most significant apoptotic changes were seen in the tubules of remnant kidneys peaking at day 120 post-SNx. At this stage, the increase in apoptosis compared to controls was 10.33±2.67 (M±SEM) fold for glomerular cells (P⩽0.006), 26.20±4.56 fold for tubular cells (P<0.0001) and 4.66±0.81 fold for interstitial cells (P⩽0.01). Parallel changes in the number of PSNA positive renal cells were observed. Maximal PCNA staining was seen at day 120 when the increase with respect to controls was 14.00±4.93 fold (P⩽0.05) for glomerular cells, 60.01±12.20 fold (P⩽0.05) for tubular cells and 28.59±4.45 fold ((P⩽0.05) for interstitial cells. As expected the number of cells undergoing division and detectable by conventional light microscopy was lower at any time point to those expressing PCNA. We also observed a close correlation between the severity of tubular atrophy and tubulointerstitial fibrosis with the rate of tubular apoptosis (r=0.970, R²=0.941, P⩽0.001). Conclusions: We have shown a time-dependent increase in apoptosis and PCNA antigen positive staining in the sub-total nephrectomy model of chronic renal failure correlating with the progression of renal fibrosis. PCNA staining did not match analysis for mitosis and was considered to overestimate the number or proliferating cells in the tissue. With this reservation in mind and taking into account the relative time-frames in vivo of apoptosis and proliferation; apoptosis potentially outweighs proliferation by a factor of 2-8-fold, when examined over the same time period. Consequently, even small changes in the finite numbers of apoptotic cells become highly significant. Our results have shown the definite role of apoptosis within progression of renal damage and highlighted how it may contribute to the progression of tubular atrophy and play a role in the pathogenesis of tubulo-interstitial scarring.     

Clinical significance of costimulatory molecules CD80/CD86 expression in IgA nephropathy

BACKGROUND: IgA nephropathy (IgAN) is the most common form of human glomerulonephritis. Tubulointerstitial inflammation with infiltration of mononuclear cells plays an important role in the progression of IgAN. Activation of T cells requires costimulatory signals through binding of CD28 receptor with cognate ligands (CD80/CD86) located on antigen-presenting cells (APC). To assess the clinical significance of this regulatory pathway participation in the pathogenesis of IgAN, a comprehensive immunohistologic evaluation was conducted on renal tissue of IgAN in different phases of progressive injury. METHODS: Thirty-three cases of IgAN and ten cases of non-IgA mesangial proliferative glomerulonephritis (PGN) with minor tissue damage as controls were investigated. Monoclonal antibodies were used to assess the expression of CD80, CD86, CD68, CD14, CD45RO, human leukocyte antigen-DR (HLA-DR), and intercellular adhesion molecule-1 (ICAM-1) in renal tissues. Clinical and expression data were compared at the time of renal biopsy. RESULTS: CD80+ and CD86+ cells were observed more in IgAN patients with progressive renal injury than in mild cases and controls. CD80 was limited to tubular epithelial cells and was complemented by HLA-DR expression. CD86 was expressed in the glomerulus, periglomerular area, and peritubular interstitium. Activated T cells (CD45RO+), monocytes (CD14+), macrophages (CD68+), and CD86 showed similar distributions. Positive correlations were found between CD86+ cells and CD45RO, CD14, and CD68 positive cells and between CD80+ tubuli and peritubular interstitial CD45RO+ cells. The number of interstitial CD86 positive cells and the percentage of CD80+ tubuli were correlated with renal function. Most CD86+ cells were monocyte/macrophages. CONCLUSION: This study suggested that CD80 and CD86 activate T cells in IgAN, CD80/CD86 expressions correlated with renal function at the time of renal biopsy, and monocyte/macrophages and tubular epithelial cells act as APC.     

The correlation between serum levels of oxidative stress indicators and renal interstitial fibrosis in patients with IgA nephropathy

Objective To investigate the relationship between serum levels of oxidative stress indicators and the degree of renal interstitial fibrosis in patients with IgA nephropathy (IgAN). Methods Seventy eight patients with confirmed primary IgAN in General Hospital of Ningxia Medical University from January 2013 to December 2014 were enrolled. The patients were divided into T0 group (n=30), T1 group (n=26) and T2 group (n=22) according to the grade of tubular atrophy/interstitial fibrosis of Oxford pathological classification criteria for IgAN in 2009. Meanwhile, thirty cases of health examiner were enrolled as control subjects. The levels of serum malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were detected by xanthine oxidase method, thiobarbituric acid spectrophotometry method, ultraviolet spectrophotometry method, chemical colorimetric method, respectively. The levels of serum advanced oxidation protein products (AOPPs), transforming growth factor beta 1 (TGF-β1), monocyte chemotactic protein 1 (MCP-1), transforming growth factor alpha (TGF-α), interleukin 6 (IL-6) and hypoxia inducible factor 1 alpha (HIF-1α) were detected by enzyme linked immunosorbent assay (ELISA) in all groups. Spearman correlation analysis was used to analyze the correlation between serum oxidative stress indicators and traditional risk factors of tubular atrophy/renal interstitial fibrosis. Multivariable linear regression analysis was used to analyze the correlation between oxidative stress indicators and degree of renal tubular atrophy/renal interstitial fibrosis. Results There were differences in serum levels of AOPPs, MDA, SOD, CAT and GSH-Px in IgAN patients with different degrees of renal interstitial fibrosis (all P﹤0.05). With the increase of renal interstitial fibrosis, the levels of AOPPs and MDA increased gradually, while the levels of SOD, CAT and GSH-Px decreased gradually. Serum AOPPs, MDA, SOD, CAT, GSH-Px concentration in IgAN patients were correlated with the mean arterial pressure (MAP), total blood protein (TP), albumin (Alb), Scr, uric acid (UA), 24-hour urinary protein volume and estimated glomerular filtration rate (eGFR). Multivariate regression analysis showed that the AOPPs levels of blood were positively correlated with MAP, Scr, UA and 24-hour urinary protein (all P﹤0.01), and negatively correlated with TP, Alb, eGFR (all P﹤0.05). The serum levels of AOPPs and MDA in IgAN patients were positively correlated with the levels of TGF-β1, MCP-1, TGF-α, IL-6 and HIF-1α. The levels of SOD, CAT and GSH-Px were negatively correlated with the levels of TGF-β1, MCP-1, TGF-α, IL-6 and HIF-1α. Multivariate stepwise regression analysis showed that the degree of renal interstitial fibrosis in IgAN patients was positively correlated with serum AOPPs level (β=0.285, P=0.001), negatively correlated with CAT (β=-0.346, P﹤0.001), GSH-Px (β=-0.303, P﹤0.001). Conclusions The level of serum oxidative stress in IgAN patients is elevated and positively correlated with the degree of renal interstitial fibrosis, suggesting that oxidative stress may be involved in the occurrence and development of renal interstitial fibrosis.     

The spectrum of acute renal failure in IgA nephropathy

Background: Acute renal failure rarely complicates the course of IgA nephropathy. In this study, we have tried to define the mode of presentation, the spectrum of morphology, and the prognostic factors for renal outcome. Methods: Twenty patients with biopsy-proven IgA nephropathy who developed acute renal failure were identified from 2000 to 2009 at a medical center in Taiwan. The patients' records were retrospectively reviewed with respect to clinical presentation, morphology of renal biopsy, and outcomes. Results: On histology, glomerular crescents were present in 11 patients (55%), acute tubular necrosis was identified in 11 patients (55%), acute interstitial nephritis was seen in 4 patients (20%), and extensive tubular red blood cell casts were present in 4 patients (20%). At the end of follow-up, 2 patients (10%) had died, 11 patients (55%) were in remission, and 7 patients (35%) developed end-stage renal disease. The prognostic factors for renal outcome were peak serum creatinine, dialysis support requirement, morphology (prominent glomerular/tubular injury), percentage of glomeruli affected by crescents, and interstitial infiltration (p = 0.04, <0.001, 0.013, 0.05, 0.02, respectively). Conclusions: Our findings suggested that there were four pathogenic mechanisms involved in IgA nephropathy with acute renal failure including (1) crescentic IgA nephropathy; (2) acute tubular necrosis associated with microhematuria and red blood cell casts occluding tubules; (3) acute tubular necrosis not related to microhematuria; and (4) acute interstitial nephritis, apparently induced by drugs. In general, patients with prominent tubular injury had a much higher remission rate than patients with prominent glomerular injury.     

The sialoadhesin (CD169) expressing a macrophage subset in human proliferative glomerulonephritis.

BACKGROUND: Sialoadhesin (Sn; CD169) is a lectin-like receptor whose expression is restricted to subsets of tissue and inflammatory macrophages. We have previously identified accumulation of Sn+ macrophages as an important marker of disease progression versus remission in rat mesangial proliferative nephritis. The current study examined the significance of Sn+ macrophages in human proliferative glomerulonephritis. METHODS: Frozen kidney sections from normal adult human kidney (n = 4) and pediatric nephropathy (n = 40) were stained for total macrophages (CD68+ cells), Sn+ macrophages, CD3+ T-cells and collagen type I by immunofluorescence. Leukocyte infiltration and the severity of glomerular lesions and interstitial damage were scored. A second protocol biopsy was performed in 27 cases and clinical and biopsy-based data obtained. RESULTS: Sn+ macrophages were absent from glomeruli in normal adult human kidney and in thin basement membrane disease (n = 4), but were detected in 4 of 9 cases of purpura nephritis; 7 of 17 IgA nephropathy; 5 of 5 membranoproliferative glomerulonephritis, and 5 of 5 lupus nephritis. Sn+ macrophages were localized in areas of focal glomerular and interstitial damage. Two-colour immunostaining confirmed that Sn+ cells are a subset of total CD68+ macrophages. The number of glomerular Sn+ macrophages correlated with the degree of proteinuria and glomerular lesions (r = 0.44, P = 0.0045 and r = 0.82, P<0.0001; respectively), while interstitial Sn+ macrophages correlated with the degree of proteinuria and interstitial damage (r = 0.59, P<0.0001 and r = 0.75, P<0.0001; respectively). Combined immunostaining revealed that interstitial Sn+ macrophages and CD3+ T-cells co-localized in areas of tubulointerstitial damage with increased type I collagen deposition. There was significant correlation between the number of interstitial Sn+ macrophages and CD3+ T-cells (r = 0.74, P<0.0001). Most patients responded to a 2 year period of glucocorticoid therapy with a reduction in proteinuria and glomerular lesions and this correlated with the reduction in the number of glomerular Sn+ macrophages. CONCLUSION: This study has identified Sn+ cells as a macrophage subset whose accumulation in the kidney correlates with proteinuria and histologic damage. These results, together with recent findings from animal studies, suggest that Sn+ macrophages may play an important role in progressive renal disease.     

An Unusual Cause of Renomegaly and Renal Insufficiency: A Case Report of Renal Involvement in Common Variable Immunodeficiency disease

Common variable immunodeficiency disease (CVID) represents a heterogeneous group of primary hypogammaglobulinemias of unknown etiology, characterized by decreased serum immunoglobulin levels and recurrent bacterial infections and is often accompanied by autoimmune disease. Renal involvement is rare in CVID, despite widespread involvement of other organ systems. We describe a 21-year-old girl who presented with recurrent infections, hepatosplenomegaly, renomegaly, and renal insufficiency. Renal biopsy revealed a remarkable diffused interstitial infiltration and severe degenerative tubular lesions. Interstitial infiltration consisted mainly of CD8⁺ T cells and CD68⁺ macrophages with less CD4⁺ T and rare B cells. For the cases with recurrent infections, multiple organomegaly, and renal insufficiency, clinicians should consider to exclude CVID, so as to make the timely diagnosis and appropriate management.