Effects of miR-195 on diabetic nephropathy rats through targeting TLR4 and blocking NF-κB pathway

Potential role of microRNA-503 in Icariin-mediated prevention of high glucose-induced endoplasmic reticulum stress

BACKGROUND

Dysregulated microRNA (miRNA) is crucial in the progression of diabetic nephropathy (DN).

AIM

To investigate the potential molecular mechanism of Icariin (ICA) in regulating endoplasmic reticulum (ER) stress-mediated apoptosis in high glucose (HG)-induced primary rat kidney cells (PRKs), with emphasis on the role of miR-503 and sirtuin 4 (SIRT4) in this process.

METHODS

Single intraperitoneal injection of streptozotocin (65 mg/kg) in Sprague-Dawley rats induce DN in the in vivo hyperglycemic model. Glucose-treated PRKs were used as an in vitro HG model. An immunofluorescence assay identified isolated PRKs. Cell Counting Kit-8 and flow cytometry analyzed the effect of ICA treatment on cell viability and apoptosis, respectively. Real-time quantitative polymerase chain reaction and western blot analyzed the levels of ER stress-related proteins. Dual luciferase analysis of miR-503 binding to downstream SIRT4 was performed.

RESULTS

ICA treatment alleviated the upregulated miR-503 expression in vivo (DN) and in vitro (HG). Mechanistically, ICA reduced HG-induced miR-503 overexpression, thereby counteracting its function in downregulating SIRT4 levels. ICA regulated the miR-503/SIRT4 axis and subsequent ER stress to alleviate HG-induced PRKs injury.

CONCLUSION

ICA reduced HG-mediated inhibition of cell viability, promotion of apoptosis, and ER stress in PRKs. These effects involved regulation of the miR-503/SIRT4 axis. These findings indicate the potential of ICA to treat DN, and implicate miR-503 as a viable target for therapeutic interventions in DN.

Astragalus Polysaccharide Ameliorates Renal Inflammatory Responses in a Diabetic Nephropathy by Suppressing the TLR4/NF-κB Pathway

Background

Diabetic nephropathy (DN), as a chronic inflammatory complication of diabetes, is characterized by hyperglycemia, albuminuria and edema, which ultimately becomes the leading cause of end-stage renal disease (ESRD). Astragalus polysaccharide (APS), extracted from the Astragalus membranaceus, was widely used in the treatment of diabetes mellitus. However, the functional roles of APS ameliorate inflammatory responses in DN, which remain poorly understood. Therefore, the purpose of this study was to explore the molecular mechanism of APS on DN in vivo and vitro models.

Methods

We explored the beneficial effects of APS in streptozotocin (STZ)-induced DN rat model and high glucose (HG)-treated glomerular podocyte model. The fasting blood glucose (FBG) and ratio of kidney weight to body weight were measured after 4 weeks of APS treatment. The renal injury parameters containing serum creatinine (Scr), blood urea nitrogen (BUN) and 24 h urinary protein were evaluated. The renal pathological examination was observed by hematoxylin-eosin (HE) staining. The levels of IL-1β, IL-6 and MCP-1 were evaluated by ELISA assay. The proliferation of podocytes was determined using CCK-8 assay and flow cytometry. qRT-PCR and Western blot analysis were performed to determine the amounts of TLR4/NF-κB-related gene expression.

Results

Our results indicated that APS effectively decreased the levels of FBG, BUN, Scr and renal pathological damage when compared with STZ-induced DN model group. Additionally, APS significantly ameliorated renal injury by reducing inflammatory cytokines IL-1β, IL-6, MCP-1 expression and inhibiting the TLR4/NF-κB pathway activity in DN rats. Consistent with the results in vitro, the HG-induced inflammatory response and proliferation of glomerular podocytes were also alleviated through APS administration.

Conclusion

We found that APS ameliorated DN renal injury, and the mechanisms perhaps related to relieving inflammatory responses and attenuating the TLR4/NF-κB signaling pathway.

MicroRNA-195a-5p Regulates Blood Pressure by Inhibiting NKCC2A

BACKGROUND

Previous studies showed that miR-195a-5p was among the most abundant microRNAs (miRNAs) expressed in the kidney.

METHODS

Lentivirus silencing of tumor necrosis factor-α (TNF) was performed in vivo and in vitro. Luciferase reporter assays confirmed that bumetanide-sensitive Na+-K+-2Cl- cotransporter isoform A (NKCC2A) mRNA is targeted and repressed by miR-195a-5p. Radiotelemetry was used to measure mean arterial pressure.

RESULTS

TNF upregulates mmu-miR-195a-5p, and -203 and downregulates mmu-miR-30c and -100 in the medullary thick ascending limb of male mice. miR-195a-5p was >3-fold higher in the renal outer medulla of mice given an intrarenal injection of murine recombinant TNF, whereas silencing TNF inhibited miR-195a-5p expression by ≈51%. Transient transfection of a miR-195a-5p mimic into medullary thick ascending limb cells suppressed NKCC2A mRNA by ≈83%, whereas transfection with Anti-miR-195a-5p increased NKCC2A mRNA. Silencing TNF in medullary thick ascending limb cells prevented increases in miR-195 induced by 400 mosmol/kg H2O medium, an effect reversed by transfection with a miR-195a-5p mimic. Expression of phosphorylated NKCC2 increased 1.5-fold in medullary thick ascending limb cells transfected with Anti-miR-195a-5p and a miR-195a-5p mimic prevented the increase, which was induced by silencing TNF in cells exposed to 400 mosmol/kg H2O medium after osmolality was increased by adding NaCl. Intrarenal injection of TNF suppressed NKCC2A mRNA, whereas injection of miR-195a-5p prevented the increase of NKCC2A mRNA abundance and phosphorylated NKCC2 expression when TNF was silenced. Intrarenal injection with miR-195a-5p markedly attenuated MAP after renal silencing of TNF in mice given 1% NaCl.

CONCLUSIONS

The study identifies miR-195a-5p as a salt-sensitive and TNF-inducible miRNA that attenuates NaCl-mediated increases in blood pressure by inhibiting NKCC2A.

Poor expression of miR-195-5p can assist the diagnosis of cerebral vasospasm after subarachnoid hemorrhage and predict adverse outcomes

OBJECTIVE

Patients with spontaneous subarachnoid hemorrhage (SAH) may develop refractory arterial cerebral vasospasm (CVS), which is the leading cause of death in SAH patients. This study explored the clinical diagnostic value of serum miR-195-5p levels in CVS after SAH (SAH + CVS) and its relationship with the prognosis of SAH + CVS.

METHODS

A total of 110 patients with spontaneous SAH were divided into the SAH group (N = 62) and SAH + CVS group (N = 58), with 60 healthy subjects as controls. The clinical data of blood glucose, blood sodium fluctuation, and serum lactic acid were recorded. miR-195-5p serum level was detected by RT-qPCR and its diagnostic value on SAH + CVS was analyzed by receiver operating characteristic curve. Serum levels of PDGF/IL-6/ET-1 and their correlation with miR-195-5p were analyzed using RT-qPCR, enzyme-linked immunosorbent assay, and Pearson's method. The patient prognosis was evaluated by Glasgow Outcome Scale. The effect of miR-195-5p levels on adverse prognosis was analyzed by Kaplan-Meier method and Cox regression analysis.

RESULTS

miR-195-5p was lowly expressed in the serum of SAH patients and lower in SAH + CVS patients. Serum miR-195-5p level assisted the diagnosis of SAH and SAH + CVS and was negatively correlated with PDGF/IL-6/ET-1 levels and was an independent risk factor together with ET-1 and blood glucose for SAH + CVS. miR-195-5p low expression predicted a higher cumulative incidence of adverse outcomes and was an independent predictor of adverse outcomes.

CONCLUSION

Poor expression of miR-195-5p can assist the diagnosis of SAH + CVS and predict higher adverse outcomes.

lncRNA MALAT1 Promotes Diabetic Nephropathy Progression via miR-15b-5p/TLR4 Signaling Axis

Objective

The long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) are closely associated with the pathogenesis of diabetic nephropathy (DN). But a complete mechanism for MALAT1 in DN has yet to be identified. This study investigated the effect of MALAT1 on DN through the regulation of miR-15b-5p/TLR4 signaling.

Method

Renal tissues were collected from DN patients. Human renal tubular epithelial cells (HK-2) were used as a model of DN induced by high glucose (HG). We then measured the viability, apoptosis, and inflammatory cytokine levels of HK-2 cells using the corresponding assays. Following transfections of si-MALAT1, si-MALAT1+miR-15b-5p inhibitor, or si-MALAT1+vector TLR4 into HG-stimulated HK-2 cells, cell viability, apoptosis, and inflammatory cytokines were again measured. Furthermore, dual-luciferase reporter assay validated the interactions of MALAT1/miR-15b-5p and miR-15b-5p/TLR4. In addition, the interaction between MALAT1 and miR-15b-5p was investigated by RNA immunoprecipitation (RIP).

Results

A significant upregulation of MALAT1 was observed in DN kidney tissues, as well as in HG-stimulated HK-2 cells. MALAT1 knockdown attenuates the inhibition of cell viability, apoptosis, and inflammatory response induced by HG in HK-2 cells. Moreover, a miR-15b-5p inhibitor or TLR4 overexpression reversed the above effects induced by MALAT1 knockdown.

Conclusion

These results indicate that reduced MALAT1 ameliorates HG-stimulated HK-2 cell damage through an inhibition of the miR-15b-5p/TLR4 axis. MALAT1 may serve as a biomarker and potential therapeutic target for DN.