Loss of the Golgi Matrix Protein 130 Cause Aberrant IgA1 Glycosylation in IgA Nephropathy.

BACKGROUND: Aberrant O-glycosylation IgA1 production is a major factor in the pathogenesis of IgA nephropathy, but the underlying mechanism is still unclear. IgA1 glycosylation modification is in Golgi, and downregulation of the Golgi peripheral membrane protein Golgi matrix protein 130 (GM130) could lead to glycosylation deficiency. In this study, we aimed to explore the role of GM130 in glycosylate deficiency IgA1 (Gd-IgA1) production. METHODS: We enrolled 27 IgA nephropathy patients, 12 patients with chronic tonsillitis, 15 non-IgAN chronic kidney disease patients, and 15 healthy volunteers as healthy control. We explored GM130 expression in Tonsillar tissue by immunofluorescence staining and Western blotting and expression in peripheral blood mononuclear cells (PBMCs) by flow cytometry. The concentration of IgA1 and level of O-glycosylation were determined by ELISA and Vicia Villosa lectin-binding assay. Real-time PCR and Western blot were used to analyze the levels of ß1,3-Gal transferase (C1GALT1) and ST6GalNAC2, respectively. To explore the contribution of GM130 in IgA1 O-glycosylation modification, cells were subjected to experiments for evaluation of GM130 silencing by GM130-siRNA transfection. RESULTS: GM130 expression was significantly decreased in tonsil tissues and PBMC of IgAN patients; the expression of C1GALT1 decreased and Gd-IgA1 level increased significantly in patients with IgAN patients. The expression of GM130 was negatively related to Gd-IgA1 production. By siRNA transfection, our results clearly indicated that the downregulation of GM130 can increase IgA1 O-glycosylation deficiency, which is thought to reduce C1GALT1 expression but not affect the expression of ST6GalNAC2. CONCLUSION: We identified and demonstrated that GM130 plays an important role in IgA1 O-glycans deficiency in IgAN patients, by negatively regulating C1GALT1 expression. We believe that this finding will provide theoretical foundations for a new mechanism of Gd-IgA1 production in IgAN patients.

Spontaneous Left Renal Subcapsular Hematoma and Right Hip Hematoma in a Hemodialysis Patient: A Case Report and Review of the Literature.

For maintenance hemodialysis (MHD) patients, the blood is in low hypercoagulable state due to the use of heparin or low molecular weight heparin during dialysis. It is not rare to see hematoma in the puncture site. In recent years, several cases have been reported of spontaneous kidney rupture, but no hip hematoma, let alone both occurred in succession. There was one MHD patient with spontaneous kidney bleeding and hip hematoma in our hospital in 2014, and we provided effective treatment and follow-up.

Efficacy of triptolide on the apoptosis of tonsillar mononuclear cells from patients with IgA nephropathy.

AIMS: This study aimed to evaluate the extent of apoptosis of tonsillar mononuclear cells (TMCs) derived from patients with IgA nephropathy (IgAN) and the effects of triptolide (TP) on the apoptosis of these TMCs. METHODS: TMCs were isolated from tonsillar tissues of patients with IgAN or chronic tonsillitis (control group). Rates of TMCs apoptosis were measured by annexin V-fluorescein isocyanate (FITC)/propidium iodide (PI)-labeled flow cytometry (FCM). Expression levels of Bcl-2 family proteins were quantified by immunohistochemistry of fixed tonsillar sections and Western blot analyzes of TMCs lysates. TMCs from IgAN patients were treated 10, 20, or 30 ng/mL TP for 24 h and then evaluated for viability by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, for the percentage of apoptotic cells by FCM, and for the relative expression levels of Bcl-2 family proteins by Western blot analysis. RESULTS: Compared to TMCs from the control group, TMCs from the IgAN group demonstrated lower rates of apoptosis, higher expression levels of the anti-apoptosis proteins Bcl-2 and Bcl-xL, and lower expression levels of the pro-apoptosis protein Bax. Treatment of IgAN patient-derived TMCs with 10, 20, or 30 ng/mL TP for 24 h suppressed the viability and promoted the apoptosis of TMCs in a dose-dependent manner. Western blot analysis revealed a TP dose-dependent decrease in Bcl-2 and Bcl-xL expression levels, in parallel with increased Bax protein levels. CONCLUSION: TMCs from IgAN patients may be in a state of inhibited apoptosis mediated by Bcl-2 family proteins, which may be reversed by TP treatment.

Targeting Renal Proximal Tubule Cells in Obesity-Related Glomerulopathy.

As a metabolic disorder, obesity can cause secondary kidney damage, which is called obesity-related glomerulopathy (ORG). As the incidence of obesity increases worldwide, so does the incidence of end-stage renal disease (ESRD) caused by ORGs. However, there is still a lack of effective strategies to prevent and delay the occurrence and development of ORG. Therefore, a deeper understanding and elaboration of the pathogenesis of ORG is conducive to the development of therapeutic drugs for ORG. Here, we review the characteristics of pathological lesions of ORG and describe the roles of lipid metabolism disorders and mitochondrial oxidative stress in the development of ORG. Finally, we summarize the current available drugs or compounds for the treatment of ORG and suggested that ameliorating renal lipid metabolism and mitochondrial function may be potential therapeutic targets for ORG.

The influences of α-hemolytic Streptococcus on class switching and complement activation of human tonsillar cells in IgA nephropathy.

While ß-hemolytic streptococcus (ß-HS) infections are known to predispose patients to acute poststreptococcal glomerulonephritis, there is evidence that implicates α-hemolytic streptococcus (α-HS) in IgA nephropathy (IgAN). The alternative pathway of the complement system has also been implicated in IgAN. We aimed to explore the association between α-HS and complement activation in human tonsillar mononuclear cells (TMCs) in IgAN. In our study, α-HS induced higher IgA levels than IgG levels, while ß-HS increased higher IgG levels than IgA levels with more activation-induced cytidine deaminase, in TMCs in the IgAN group. Aberrant IgA1 O-glycosylation levels were higher in IgAN patients with α-HS. C3 and C3b expression was decreased in IgAN patients, but in chronic tonsillitis control patients, the expression decreased only after stimulation with ß-HS. Complement factor B and H (CFH) mRNA increased, but the CFH concentration in culture supernatants decreased with α-HS. The percentage of CD19 + CD35 + cells/complement receptor 1 (CR1) decreased with α-HS more than with ß-HS, while CD19 + CD21 + cells/complement receptor 2 (CR2) increased more with ß-HS than with α-HS. The component nephritis-associated plasmin receptor (NAPlr) of α-HS was not detected on tonsillar or kidney tissues in IgAN patients and was positive on cultured TMCs and mesangial cells. We concluded that α-HS induced the secretion of aberrantly O-glycosylated IgA while decreasing the levels of the inhibitory factor CFH in culture supernatants and CR1 + B cells. These findings provide testable mechanisms that relate α-HS infection to abnormal mucosal responses involving the alternative complement pathway in IgAN.

RBP4 Is Associated With Insulin Resistance in Hyperuricemia-Induced Rats and Patients With Hyperuricemia.

Objective: Hyperuricemia (HUA) is strongly associated with abnormal glucose metabolism and insulin resistance (IR). However, the precise molecular mechanism of HUA-induced IR is still unclear. Retinol binding protein 4 (RBP4) has been shown to induce IR in type 2 diabetes mellitus. This study was designed to clarify the relationship between RBP4 and HUA-induced IR and its potential mechanisms. Methods: Patients with HUA were collected to detect the levels of plasma RBP4 and clinical biochemical indicators. Rats were fed with 10% high yeast and oteracil potassium (300 mg/kg) via intraperitoneal injection once daily for eight weeks, and gavage with adenine (100 mg/kg) once daily from the fifth week to induce the HUA model. Glucose consumption testing was performed to determine the capacity of glucose intake and consumption in 3T3-L1 adipocytes. Real-time polymerase chain reaction (RT-PCR) and western blot were used to detect the mRNA and protein level of RBP4 and insulin receptor substrate-phosphatidylinositol 3-kinase-active protein kinase (IRS/PI3K/Akt) signaling pathway-related proteins. Results: The levels of plasma RBP4 in both HUA patients and HUA rat models were significantly higher than that in the control groups. The level of plasma RBP4 was positively correlated with plasma uric acid, creatinine, fasting insulin, IR index, total cholesterol and triglyceride levels in patients with HUA. In HUA rats, the level of plasma RBP4 was positively correlated with plasma uric acid, IR index, and triglycerides. HUA rats also exhibited IR. After inhibition of RBP4 expression, the phosphorylation levels of the IRS/PI3K/Akt signaling pathway were increased, and IR was significantly improved. Conclusion: HUA induced IR both in vitro and in vivo. RBP4 may be involved in HUA-induced IR by inhibiting IRS/PI3K/Akt phosphorylation. Our findings may provide a new insight for the treatment of IR caused by HUA.

microRNA-630 Regulates Underglycosylated IgA1 Production in the Tonsils by Targeting TLR4 in IgA Nephropathy.

IgA nephropathy (IgAN) is the most common primary glomerular disease. The characteristic pathology involves immune complexes formed by the deposition of IgA1 and underglycosylated IgA1 aggregates in the mesangial area, which may be accompanied by the deposition of IgG and/or IgM and complement components. However, the molecular mechanisms of IgAN remain unclear. In the present study, microarray analysis showed that the expression of microRNA-630 (miR-630) was significantly reduced in palatal tonsils from IgAN patients compared with chronic tonsillitis. Additionally, bioinformatic analysis showed that Toll-like receptor 4 (TLR4) was the predicted target gene of miR-630 and was regulated by miR-630. When miR-630 was overexpressed in palatal tonsil mononuclear cells from IgAN patients, the expression of TLR4 was reduced and the content of IgA1 in the cell culture supernatant was decreased, and the level of galactosylation in the IgA1 hinge region was increased. Moreover, immunohistochemical analysis showed that the expression of TLR4 in IgAN patients was significantly increased. After knocking down the expression of TLR4, both the concentration of IgA1 and the binding force of IgA1 with broad bean lectin were significantly reduced in IgAN. Furthermore, the mechanism study demonstrated that TLR4 might regulate the expression of IL-1ß and IL-8 through NF-κB signaling pathway to modulate the concentration of IgA1 and the glycosylation level of IgA1. This interesting finding may offer new insight into the molecular mechanism of IgAN.

LncRNA MALAT1 promoted high glucose-induced pyroptosis of renal tubular epithelial cell by sponging miR-30c targeting for NLRP3.

Diabetic nephropathy (DN), characterized by the chronic loss of kidney function during diabetes, is a long-term kidney disease that affects millions of populations. However, the etiology of DN remains unclear. DN cell model was established by treating HK-2 cells with high glucose (HG) in vitro. Expression of metastasis-associated lung adenocarcinoma transcript-1 (MALAT1), miR-30c, nucleotide binding and oligomerization domain-like receptor protein 3 (NLRP3), caspase-1, IL-1ß, and IL-18 in treated HK-2 cells were tested by quantitative polymerase chain reaction. HK-2 cell pyroptosis was assessed using flow cytometry analysis. Lactate dehydrogenase (LDH) activity was examined with a LDH assay kit. Correlation among MALAT1, miR-30c, and NLRP3 was examined via dual-luciferase reporter assay. Here, we revealed that MALAT1 was upregulated, but miR-30c was downregulated in HG-treated HK-2 cells, leading to upregulation of NLRP3 expression and cell pyroptosis. Knockdown of MALAT1 or overexpression of miR-30c protected HK-2 cells from HG-induced pyroptosis. Meanwhile, we found that MALAT1 promoted NLRP3 expression by sponging miR-30c through dual-luciferase reporter assay. Moreover, the co-transfection of sh-MALAT1 and miR-30c inhibitor could reverse the protective effects of the sh-MALAT1 on the HG-induced pyroptosis. These results confirmed that MALAT1 regulated HK-2 cell pyroptosis by inhibiting miR-30c targeting for NLRP3, contributing to a better understanding of DN pathogenesis and help to find out the effective treatment for DN.

Functional Role of SUV39H1 in Human Renal Tubular Epithelial Cells Under High-glucose Ambiance.

SUV39H1, the histone methyltransferase (HMTase) of histone H3 lysine 9 trimethylation (H3K9me3), is a known transcriptional repressor of inflammatory genes. The effect of SUV39H1 on inflammatory gene promoters under high-glucose stimulation in vascular smooth muscle cells (VSMCs), macrophages, and cardiomyocytes has been studied, but how SUV39H1 functions in renal tubules under diabetic conditions is unclear. Renal biopsy specimens of ten diabetic nephropathy (DN) subjects and seven non-DN minimal change diseases (MCD) subjects were collected. SUV39H1, IL-6, and MCP-1 expression in renal tissues were measured using immunohistochemical, while SUV39H1, H3K9me3, IL-6, and MCP-1 in human proximal tubular epithelial cells (HK-2) under varying glucose conditions were assayed by Western blot and ELISA. SUV39H1 was overexpressed in HK-2 cells; the regulation of SUV39H1 and H3K9me3 on NF-κB, IL-6, MCP-1, caspase 3, and apoptosis was measured. SUV39H1 was expressed more in diabetic human renal tubules. HK-2 cells with high glucose up-regulated IL-6 and MCP-1 in a dose- and time-dependent manner, and SUV39H1 expression was reduced with greater glucose and prolonged stimulation. Expression of H3K9me3 was synchronized with SUV39H1. Moreover, overexpression of SUV39H1 in high glucose environment was accompanied with increased H3K9me3 and decreased inflammation and apoptosis. SUV39H1 dysregulation may be involved in DN progression. Overexpression of SUV39H1 may reduce renal inflammation and apoptosis via epigenetic modulation, thus plays a protective role in DN.

Vibration Induces BAFF Overexpression and Aberrant O-Glycosylation of IgA1 in Cultured Human Tonsillar Mononuclear Cells in IgA Nephropathy.

Objective. To investigate the influence of in vitro vibratory stimulation of human tonsillar mononuclear cells (TMCs). Methods. Fourteen IgA nephropathy (IgAN) patients with chronic tonsillitis (CT) and 12 CT patients with no renal pathology were enrolled. Group A TMCs were collected after 24 hours of culture and used to determine baseline levels. TMCs in groups B, C, D, E, and F were exposed to vibratory stimulation (60 Hz) for 0 (as the control group), 1, 3, 5, and 10 minutes, respectively. Results. Baseline concentrations of B-cell-activation factor (BAFF) and IgA1, BAFF mRNA expression, and aberrant O-glycosylation IgA1 level were higher in the IgAN group as compared to that in the CT group, and all increased after vibratory stimulation. Baseline mRNA expressions of core ß1,3-galactosyltransferase (C1GALT1) and core ß1,3GalT-specific molecular chaperone (Cosmc) were lower in the IgAN group; the levels decreased further after vibratory stimulation. Conclusion. In patients with IgAN, vibratory stimulation of TMCs appears to induce IgA1 secretion through activation of BAFF release and to aberrant O-glycosylation IgA1 by suppressing C1GALT1 and Cosmc expression. In vitro vibratory stimulation of human TMCs mimics the vibratory simulation of palatine tonsils produced by vocal cords during phonation.

Potential diagnostic biomarkers for IgA nephropathy: a comparative study pre- and post-tonsillectomy.

OBJECTIVE: The proteins BAFF, ST6GALNAC2, C1GALT1, and COSMC in peripheral blood mononuclear cells (PBMCs) and plasma levels of IgA1 and galactose-deficient IgA1 (Gd-IgA1) are potential biomarkers for IgAN nephropathy. In this study, we comparatively studied the changes of those biomarkers before and after tonsillectomy. METHODS: Peripheral blood samples were obtained from 16 IgAN patients with pre- and post-tonsillectomy. IgAN was diagnosed based on results from analysis of percutaneous renal biopsy tissue. Peripheral blood samples from three patients without renal diseases (non-IgAN), before and after tonsillectomy, and 16 healthy controls were also examined. BAFF, ST6GALNAC2, C1GALT1, and COSMC mRNA levels in PBMCs were detected using real-time PCR. Plasma IgA1 content was measured by ELISA. Gd-IgA1 levels were determined using the VV lectin-ELISA method. RESULTS: BAFF, ST6GALNAC2, C1GALT1, and COSMC mRNA levels and the plasma concentrations of IgA1 and Gd-IgA1 in IgAN patients before tonsillectomy were significantly higher than those in healthy controls (P < 0.05). Tonsillectomy significantly increased the expression of BAFF and ST6GALNAC2, and plasma IgA1 level, while it downregulated that of C1GALT1 and COSMC (P < 0.05). However, in non-IgAN patients, tonsillectomy did not affect the mRNA levels of BAFF, ST6GALNAC2, C1GALT1, and COSMC, plasma IgA1 content and Gd-IgA1 level. Positive correlations were established between BAFF and IgA1 (r = 0.604, P < 0.01) and between ST6GALNAC2 and Gd-IgA1 (r = 0.623, P < 0.01). CONCLUSIONS: Tonsillectomy changes the mRNA levels of BAFF, ST6GALNAC2, C1GALT1, and COSMC in PBMCs, as well as the plasma IgA1 level in IgAN patients. BAFF and ST6GALNAC2 might regulate IgA1 secretion and O-glycosylation.