Xueguang Zhang

Tissue inhibitor of metalloproteinase-1 exacerbated renal interstitial fibrosis through enhancing inflammation

BACKGROUND Tissue inhibitor of metalloproteinase-1 (TIMP-1) is associated with renal fibrosis. Furthermore, it is a multi-functional protein, and whether it has other roles in renal fibrosis is unknown. As several inflammatory mediators are substrates of matrix metalloproteinases (MMPs), TIMP-1 might affect renal fibrosis via inflamatory pathways. METHODS Plasmids containing the sense and antisense human TIMP-1 sequence were stably transfected into the human kidney proximal tubular epithelial cell line (HKC), MMP-2 and MMP-9 siRNA were transiently transfected into HKC and the transfected cells were stimulated with phorbol 12-myristate 13-acetate (PMA). In vivo, we established unilateral ureteral obstruction (UUO) models by using homozygote human TIMP-1 transgenic mice. The expression of intercellular adhesion molecule-1 (ICAM-1) in transfected cells and F4/80-positive cells in the renal interstitium were examined by indirect immunofluorescence. Protein levels in the cells and UUO models were examined by western blot, and the activities of the gelatinases and TIMP-1 were examined by gelatin zymography and reverse zymography, respectively. RESULTS After stimulation with PMA, the activities of the gelatinases were decreased, ICAM-1 was upregulated, and soluble ICAM-1 in the supernatant was decreased, in HKC transfected with sense TIMP-1, and ICAM-1 was increased in HKC transfected with MMP-9 siRNA. At 14 days after UUO, it was found that compared with wild-type mice, in transgenic mice, with upregulation of TIMP-1, activities of gelatinases were downregulated, ICAM-1, transforming growth factor-beta1 (TGF-beta1), collagens I and III were upregulated, and the extent of renal fibrosis and infiltration of macrophages was more severe. CONCLUSION Overexpression of TIMP-1 could promote renal interstitial fibrosis through the inflammatory pathway, which might be partly induced by upregulating ICAM-1.

TIMP-1 Transgenic Mice Recover From Diabetes Induced by Multiple Low-Dose Streptozotocin

Type 1 diabetes results from autoimmune destruction of the insulin-producing β-cells of pancreatic islets, of which the capacity for self-replication in the adult is too limited to restore following extensive tissue injury. Tissue inhibitor of metalloproteinase (TIMP)-1 inhibits matrix metalloproteinase activity and regulates proliferation and apoptosis of a variety of cells types, depending on the context. Here, we show that overexpression of human TIMP-1 in pancreatic β-cells of transgenic mice counteracts the cytotoxicity and insulitis induced by multiple low-dose streptozotocin (MLDS). Nontransgenic mice developed severe hyperglycemia, hypoinsulinemia, and insulitis 2 weeks after streptozotocin administration and died within 17 weeks. However, MLDS-treated transgenic mice gradually normalized the metabolic parameters and survived. β-Cell mass increased in parallel as a result of enhancement of β-cell replication. Thus, our results have demonstrated for the first time that overexpression of TIMP-1 in β-cells enhances the replication of pancreatic islets β-cells and counteracts type 1 diabetes, indicating that the TIMP-1 gene may be a potential target to prevent, or even reverse, type 1 diabetes.

Autophagy can repair endoplasmic reticulum stress damage of the passive Heymann nephritis model as revealed by proteomics analysis

Membranous nephropathy is a common cause of nephrotic syndrome in adults. Although many mechanisms have been proposed, whole proteomic research is still lacking. We analyzed the passive Heymann nephritis animal model using label-free quantitative proteome technology. Results showed 160 differential proteins between control and PHN model groups at days 14 and 21. The expression level of endoplasmic reticulum stress (ERS)-associated protein GRP78 and GRP94 protein was up-regulated on day 14 or 21, which was confirmed by Western blotting. The results also showed that the autophagy marker LC3 was up-regulated in the models. Furthermore, we used tunicamycin to induce ERS of podocytes in vitro to investigate the mechanism. Results of Western blotting revealed that the expression of GRP78, GRP94, and LC3 was up-regulated, while that of the cytoskeletal protein tubulin-β was down-regulated, and immunofluorescence displayed disordered distribution of tubulin-β. These suggest that ERS plays an important role in podocyte damage. Autophagy can repair the cytoskeleton damage caused by ERS as a protective mechanism. This provides an important basis for a thorough understanding of the mechanism of podocyte damage and the pathogenesis of membranous nephropathy.

Identifying Parameters to Distinguish Non-Diabetic Renal Diseases from Diabetic Nephropathy in Patients with Type 2 Diabetes Mellitus: A Meta-Analysis

Background Renal injuries in patients with diabetes include diabetic nephropathy (DN) and non-diabetic renal diseases (NDRD). The value of a clinical diagnosis of DN and NDRD remains inconclusive. We conducted a meta-analysis of the literature to identify predictive factors of NDRD and to compare the clinical characteristics of DN and NDRD for differential diagnosis. Methods We searched PubMed (1990 to January 2012), Embase (1990 to February 2009), and CNKI (1990 to January 2012) to identify studies that enrolled patients with DN and NDRD. Then, the quality of the studies was assessed, and data were extracted. The results were summarized as odds ratios (ORs) for dichotomous outcomes and weighted mean differences (WMDs) for continuous outcomes. Results Twenty-six relevant studies with 2,322 patients were included. The meta-analysis showed that the absence of diabetic retinopathy (DR) predicts NDRD (OR, 0.15; 95% confidence interval [CI], 0.09–0.26, p<0.00001). A shorter duration of diabetes mellitus (DM) also predicted NDRD (weighted mean difference, −34.67; 95% CI, −45.23–−24.11, p<0.00001). The levels of glycosylated hemoglobin (HbA1C%), blood pressure (BP), and total cholesterol were lower in patients with NDRD, whereas triglycerides and body mass index were higher. Other clinical parameters, including age, 24-h urinary protein excretion, serum creatinine, creatinine clearance, blood urea nitrogen, and glomerular filtration rate were not different between patients with NDRD and DN. Conclusions We identified that the absence of DR, shorter duration of DM, lower HbA1C, and lower BP may help to distinguish NDRD from DN in patients with diabetes. This could assist clinicians in making a safe and sound diagnosis and lead to more effective treatments.

Tissue inhibitor of metalloproteinase-1 promotes NIH3T3 fibroblast proliferation by activating p-Akt and cell cycle progression.

Tissue inhibitor of metalloproteinase-1 (TIMP-1) plays various roles in cell growth in different cell types. However, few studies have focused on TIMP-1’s effect on fibroblast cells. In this study, we investigated the effects of TIMP-1 overexpression on NIH3T3 fibroblast proliferation and potential transduction signaling pathways involved. Overexpression of TIMP-1, by transfection of the pLenti6/V5-DESTTIMP-1 plasmid, significantly promoted NIH3T3 proliferation as determined by the BrdU array. Neither 5 nor 15 nM GM6001 (matrix metalloproteinase system inhibitor) affected NIH3T3 proliferation, but 45 nM GM6001 inhibited proliferation. TIMP-1 overexpression activated the p-Akt pathway, but not the p-ERK or p-p38 pathway. In TIMP-1-transfected cells, cyclinD1 was upregulated and p21CIP1 and p27KIP1 were downregulated, which promoted cell entry into the S and G2/M phases. The PI3-K inhibitor LY294002 abolished the TIMP-1-induced effects. Overexpression of intracellular TIMP-1 stimulated NIH3T3 fibroblast proliferation in a matrix metalloproteinase (MMP)-independent manner by activating the p-Akt pathway and related cell cycle progression.

Aging Promotes Progression of IgA Nephropathy: A Systematic Review and Meta-Analysis

Background: There has been considerable interest in whether old age is associated with IgA nephropathy (IgAN) progression, which is still controversial. Methods: We searched multiple databases for studies published from 1980 to 2012. The inclusion criteria were case-control, cohort studies published in any language. The included studies needed to have an older group. IgAN was proven by biopsy. Results: We included 9 studies with a total of 6,543 patients. The meta-analyses of other risk factors between the older group (>50 years old) and the non-older group (15-50 years old) found significant differences in the presence of hypertension, proteinuria, serum cholesterol levels and baseline renal function. In the overall analysis, compared to the non-older group, older age significantly increased the incidence of developing end-stage renal disease [ESRD; relative risk (RR) random model 1.95; 95% CI: 1.27-3.01]. In the subgroup analyses, we found the age limit and traditional risk factors of IgAN may be the sources of heterogeneity between studies. Moreover, the RR (2.56) of the Asian countries was much higher than the RR (1.11) of the European countries. Conclusions: This comprehensive review revealed that old age is a real risk factor for IgAN progression to ESRD. The incidence of ESRD in the older IgAN patients was 1.95 times higher than that in the non-older IgAN patients. Moreover, the risk of IgAN progression to ESRD of the older patients in Asia was higher than that of the older patients in Europe.

Genomic and Epigenomic Analyses of Monozygotic Twins Discordant for Congenital Renal Agenesis

Monozygotic twins have been widely studied to distinguish genetic and environmental factors in the pathogenesis of human diseases. For renal agenesis, the one-sided absence of renal tissue, the relative contributions of genetic and environmental factors to its pathogenesis are still unclear. In this study of a pair of monozygotic twins discordant for congenital renal agenesis, the genomic profile was analyzed from a set of blood samples using high-throughput exome-capture sequencing to detect single-nucleotide polymorphisms (SNPs), copy number variations (CNVs), and insertions and deletions (indels). Also, an epigenomic analysis used reduced-representation bisulfite sequencing to detect differentially methylated regions (DMRs). No discordant SNPs, CNVs, or indels were confirmed, but 514 DMRs were detected. KEGG analysis indicated the DMRs localized to 10 signaling pathways and 25 genes, including the mitogen-activated protein kinase pathway and 6 genes (FGF18, FGF12, PDGFRA, MAPK11, AMH, CTBP1) involved in organ development. Although methylation results from our adult patient and her sister may not represent the pattern that was present during kidney development, we could at least confirm a lack of obvious differences at the genome level, which suggests that nongenetic factors may be involved in the pathogenesis of renal agenesis.

Fasudil ameliorates rhabdomyolysis-induced acute kidney injury via inhibition of apoptosis.

During times of war or natural disasters, rhabdomyolysis leading to acute kidney injury (AKI) can assume epidemic proportions. Fasudil attenuates ischemia/reperfusion-induced AKI. We investigated the therapeutic effect of an early application of fasudil on AKI induced by rhabdomyolysis and explored the potential mechanisms. Male Wistar rats were randomly divided into a control group (saline, 7 mL/kg, i.m.), a Gly group (50% glycerol, 7 mL/kg, i.m.), and a fasudil group (50% glycerol, 7 mL/kg, i.m.; fasudil, 20 mg/kg bodyweight, i.p., three times every 24 h beginning 72 h before glycerol administration). Serum creatinine, blood urea nitrogen (BUN), and histopathological changes were used to demonstrate kidney function 24 h after the glycerol injection. Cell apoptosis and the expression of rho-associated protein kinase member (ROCK1), phosphatase and tensin homolog (PTEN), P-Akt, and caspase-8, -9, and -3 were measured. Serum creatinine and BUN levels increased significantly in Gly group compared with control group. Both levels decreased after fasudil treatment. The renal tubular damage score was significantly lower and cell apoptosis was significantly less in fasudil group compared with Gly group. The expression levels of ROCK1, PTEN, and caspase-8, -9, and -3 were upregulated significantly in Gly group, and their expression was reduced in the fasudil group. The P-Akt level was decreased in Gly group and upregulated significantly in fasudil group. Early application of fasudil reduced rhabdomyolysis-associated renal injury by inhibiting Rho kinase and thereby activating the PI-3K/Akt pathway, which decreased cell apoptosis via both the intrinsic and extrinsic apoptotic pathways.

Clinical and pathological analysis of hepatitis B virus-related membranous nephropathy and idiopathic membranous nephropathy.

OBJECTIVE The Hepatitis B virus infection rate is high in the Chinese population. The implications of HBV infection are widely recognized, and membranous glomerulonephritis is the most common renal lesion associated with HBV infection. We compared the clinicopathologic features of 119 HBV-related membranous nephropathy (HBV-MN) and 143 idiopathic membranous nephropathy (IMN) patients to identify those factors that facilitate their discrimination. METHODS Cohort analysis of demographic information, clinical manifestations, laboratory parameters, renal pathology and prognostic features of the two groups. RESULTS Most HBV-MN patients were young or middle-aged; the onset age in the HBVMN group was younger than the IMN group (p < 0.05). A male predominance was found in both groups. And the two groups both presented with heavy proteinuria or nephrotic syndrome. In contrast to IMN patients, the HBV-MN group was presented with a high occurrence of microscopic hematuria (73.95 vs. 35.66%) and renal insufficiency (47.06 vs. 24.48%). Plasma complement C3 and C4 in HBV-MN patients were significantly lower than in IMN patients (p < 0.05). The hyperlipidemia was more severe in IMN patients (p < 0.05). The occurrences of segmental glomerular damage, mesangial cell proliferation and tubulointerstitial damage were more common in the HBV-MN group (p < 0.05). Immunofluorescence staining of polyclonal immunoglobulin and polytypic complement immunoglobulin were more frequent in the HBV-MN group. The followup data showed there were no statistic differences in the prognosis between HBV-MN and IMN. CONCLUSION HBV-MN patients commonly showed nephrotic syndrome accompanied with renal and hepatic dysfunction which was different from IMN patients. The primary pathological feature of HBVMN was atypical membranous nephropathy, which is usually associated with the inflammatory changes in HBV infection. The renal survival rates did not differ between HBVMN patients and IMN patients.

Profiling and initial validation of urinary microRNAs as biomarkers in IgA nephropathy

Background. MicroRNAs (miRNAs) have been found in virtually all body fluids and used successfully as biomarkers for various diseases. Evidence indicates that miRNAs have important roles in IgA nephropathy (IgAN), a major cause of renal failure. In this study, we looked for differentially expressed miRNAs in IgAN and further evaluated the correlations between candidate miRNAs and the severity of IgAN. Methods. Microarray and RT-qRCR (real-time quantitative polymerase chain reaction) were sequentially used to screen and further verify miRNA expression profiles in urinary sediments of IgAN patients in two independent cohorts. The screening cohort consisted of 32 urine samples from 18 patients with IgAN, 4 patients with MN (membranous nephropathy), 4 patients with MCD (minimal changes disease) and 6 healthy subjects; the validation cohort consisted of 102 IgAN patients, 41 MN patients, 27 MCD patients and 34 healthy subjects. The renal pathological lesions of patients with IgAN were evaluated according to Lee’s grading system and Oxford classification. Results. At the screening phase, significance analysis of microarrays analysis showed that no miRNA was differentially expressed in the IgAN group compared to all control groups. But IgAN grade I–II and III subgroups (according to Lee’s grading system) shared dysregulation of two miRNAs (miR-3613-3p and miR-4668-5p). At the validation phase, RT-qPCR results showed that urinary level of miR-3613-3p was significantly lower in IgAN than that in MN, MCD and healthy controls (0.47, 0.44 and 0.24 folds, respectively, all P < 0.01 by Mann–Whitney U test); urinary level of miR-4668-5p was also significantly lower in IgAN than that in healthy controls (0.49 fold, P < 0.01). Significant correlations were found between urinary levels of miR-3613-3p with 24-hour urinary protein excretion (Spearman r = 0.50, P = 0.034), eGFR (estimated glomerular filtration rate) (r = − 0.48, P = 0.043) and Lee’s grades (r = 0.57, P = 0.014). Similarly, miR-4668-5p was significantly correlated with eGFR (r = − 0.50, P = 0.034) and Lee’s grades (r = 0.57, P = 0.013). For segmental glomerulosclerosis according to Oxford classification, patients scored as S0 had significantly lower levels of urinary miR-3613-3p and miR-4668-5p than those scored as S1 (0.41 and 0.43 folds, respectively, all P < 0.05). Conclusions. The expression profile of miRNAs was significantly altered in urinary sediments from patients with IgAN. Urinary expression of miR-3613-3p was down-regulated in patients with IgAN. Moreover, urinary levels of both miR-3613-3p and miR-4668-5p were correlated with disease severity. Further studies are needed to explore the roles of miR-3613-3p and miR-4668-5p in the pathogenesis and progression of IgA nephropathy.