The miR-26a-5p/IL-6 axis alleviates sepsis-induced acute kidney injury by inhibiting renal inflammation

Sepsis-induced acute kidney injury (AKI) is a common and life-threatening complication in hospitalized and critically ill patients and has unacceptable morbidity and mortality rates. However, effective approaches for the diagnosis and treatment of septic AKI are still lacking. Here, we demonstrated significant increases in the miR-26a-5p levels in renal tubular cells of LPS-induced septic AKI models both in vivo and in vitro. Mechanistically, we provided evidence of the involvement of NF-κB in miR-26a-5p induction. LPS treatment of renal tubular cells led to the activation of NF-κB, and inhibition of NF-κB by TPCA-1 prevented the induction of miR-26a-5p. These results indicated that NF-κB was a key upstream factor for the induction of miR-26a-5p in septic AKI. Anti-miR-26a-5p enhanced the expression of IL-6 at both the protein and mRNA levels following LPS treatment. Furthermore, our luciferase microRNA target reporter assay verified that IL-6 is a direct target of miR-26a-5p. Blocking miR-26a-5p promoted renal inflammation and worsened kidney injury. Thus, our study indicated that the miR-26a-5p/IL-6 axis can alleviate sepsis-induced acute kidney injury by inhibiting renal inflammation. This mechanism may represent a therapeutic target for septic AKI.     

miR-34b-5p promotes renal cell inflammation and apoptosis by inhibiting aquaporin-2 in sepsis-induced acute kidney injury

ObjectiveThis study was designed to uncover the mechanism of miR-34b-5p-mediated aquaporin-2 (AQP2) in sepsis-induced injury using human renal tubular epithelial cells (HK-2).MethodsSerum levels of miR-34b-5p, TNF-α, IL-1β, IL-6, serum creatinine (SCr), and blood urea nitrogen (BUN) in septic patients with acute kidney injury (AKI) and healthy controls were detected. Lipopolysaccharide (LPS) was used to induce sepsis in HK-2 cells. LPS-induced HK-2 cells were transfected with miR-34b-5p inhibitor, miR-34b-5p mimic, pcDNA3.1-AQP2, si-AQP2, miR-34b-5p inhibitor + si-NC, or miR-34b-5p inhibitor + si-AQP2. The expressions of miR-34b-5p, AQP2, Bax, Bcl-2, cleaved caspase-3, TNF-α, IL-1β, and IL-6 in HK-2 cells were detected. TUNEL staining revealed the apoptosis of HK-2 cells. Dual-luciferase reporter assay verified the binding between miR-34b-5p and AQP2.ResultsThe expression of miR-34b-5p and the inflammatory responses were augmented in septic AKI patients. miR-34b-5p was up-regulated and AQP2 was down-regulated in LPS-induced HK-2 cells. miR-34b-5p inhibition or AQP2 overexpression ameliorated apoptosis and inflammation in LPS-induced HK-2 cells. In contrast, overexpressing miR-34b-5p deteriorated LPS-induced injury in HK-2 cells. AQP2 was a downstream target of miR-34b-5p. AQP2 silencing abolished the suppressive effects of miR-34b-5p inhibition on LPS-induced apoptosis and inflammatory response in HK-2 cells.ConclusionmiR-34b-5p inhibits AQP2 to promote LPS-induced injury in HK-2 cells.     

LncRNA MALAT1-deficiency restrains lipopolysaccharide (LPS)-induced pyroptotic cell death and inflammation in HK-2 cells by releasing microRNA-135b-5p

Long non-coding RNAs (LncRNAs) participate in the regulation of chronic kidney disease (CKD), and acute kidney injury (AKI) is identified as an important risk factor for CKD. This study investigated the involvement of a novel LncRNA MALAT1 in regulating lipopolysaccharide (LPS)-induced cell pyroptosis and inflammation in the human renal tubular epithelial HK-2 cells. Here, the HK-2 cells were subjected to LPS (2 μg/mL) treatment to establish cellular AKI models in vitro, and we validated that LPS triggered NLRP3-mediated pyroptotic cell death, promoted cell apoptosis and inflammation-associated cytokines secretion to induce HK-2 cell injury. Then, a novel LncRNA MALAT1/miRNA (miRNA)-135b-5p axis was verified to rescue cell viability in LPS treated HK-2 cells by targeting NLRP3. Mechanistically, miRNA-135b-5p bound to LncRNA MALAT1, and LncRNA MALAT1 positively regulated NLRP3 through acting as RNA sponger for miRNA-135b-5p. Further gain- and loss-of-function experiments evidenced that both LncRNA MALAT1 ablation and miRNA-135b-5p overexpression reversed LPS-induced cell pyroptosis, apoptosis, and inflammation in the HK-2 cells, and the protective effects of LncRNA MALAT1 knock-down on LPS-treated HK-2 cells were abrogated by silencing miRNA-135b-5p. In general, our study firstly investigated the role of the LncRNA MALAT1/ miRNA-135b-5p/NLRP3 signaling cascade in regulating LPS-induced inflammatory death in HK-2 cells.     

长链非编码核糖核酸LINC00261通过miR-148b-3p/PTEN途径对高糖环境中HK-2细胞的保护作用

目的探讨长链非编码RNA(lncRNA)LINC00261在糖尿病肾病中的表达,及其可能通过微小核糖核酸miR-148b-3p/PTEN途径对高糖环境中HK-2细胞的保护作用。 方法选择2016年3月至2018年5月本院的19例糖尿病肾病患者和23例健康对照者,采集血样,通过实时定量PCR(qRT-PCR)测定LINC00261和miR-148b-3p的表达。在细胞实验中,将HK-2肾小管上皮细胞分为7组：正常葡萄糖组(5.5 mmol/L培养,NG组)、高葡萄糖糖组(30.0 mmol/L培养,HG组)、其余5组也均为高葡萄糖培养：空质粒转染pcDNA(HG+pcDNA组)、转染LINC00261(HG+pcDNA-LINC00261组)、转染阴性对照anti-miR-NC(HG+anti-miR-NC组)、转染抑制剂anti-miR-148b-3p(HG+anti-miR-148b-3p组)、LncRNA和miRNA同时转染(HG+pcDNA-LINC0026+miR-148b-3p组)。应用Western印迹、细胞计数试剂盒8和流式细胞术分别检测PTEN蛋白表达、细胞增殖与凋亡。测超氧化物歧化酶(SOD)试剂盒和丙二醛(MDA)试剂盒分别检测SOD活性和MDA含量。双荧光素酶报告实验用于LINC00261、miR-148b-3p、PTEN的相互关系鉴定。 结果与健康对照者比较,糖尿病肾病患者的LINC00261表达明显降低,而miR-148b-3p表达则明显增高(P<0.05)。过表达LINC00261或抑制miR-148b-3p后,高糖环境中HK-2细胞的miR-148b-3p表达、细胞凋亡及MDA含量均下降,而PTEN蛋白表达、细胞增殖及SOD活性均增高(P<0.05)。 结论LINC00261可能通过调控miR-148b-3p/PTEN途径,促进高糖环境中HK-2肾小管上皮细胞增殖、降低氧化应激、减少细胞凋亡。     

MicroRNA-122-5p ameliorates tubular injury in diabetic nephropathy via FIH-1/HIF-1α pathway

Diabetes kidney disease (DKD) affects approximately one-third of diabetes patients, however, the specific molecular mechanism of DKD remains unclear, and there is still a lack of effective therapies. Here, we demonstrated a significant increase of microRNA-122-5p (miR-122-5p) in renal tubular cells in STZ induced diabetic nephropathy (DN) mice. Moreover, inhibition of miR-122-5p led to increased cell death and serve tubular injury and promoted DN progression following STZ treatment in mice, whereas supplementation of miR-122-5p mimic had kidney protective effects in this model. In addition, miR-122-5p suppressed the expression of factor inhibiting hypoxia-inducible factor-1 (FIH-1) in vitro models of DN. microRNA target reporter assay further verified FIH-1 as a direct target of miR-122-5p. Generally, FIH-1 inhibits the activity of HIF-1α. Our in vitro study further indicated that overexpression of HIF-1α by transfection of HIF-1α plasmid reduced tubular cell death, suggesting a protective role of HIF-1α in DN. Collectively, these findings may unveil a novel miR-122-5p/FIH-1/HIF-1α pathway which can attenuate the DN progression.     

Downregulation of miR-574-5p inhibits HK-2 cell viability and predicts the onset of acute kidney injury in sepsis patients

BackgroundIncreased levels of microRNA-574-5p (miR-574-5p) have been found to be associated with increased survival of septic patients, indicating the potential role of miR-574-5p in protecting against septic progression and complications. Acute kidney injury (AKI) is one of the most common and serious complications of sepsis. Therefore, the aim of this study was to test these hypotheses: (1) in a renal cell culture line (HK-2), upregulated expression of miR-574-5p increases, and downregulated expression of miR-574-5p decreases cell viability, and (2) serum levels of miR-574-5p from patients with sepsis and AKI are lower than those of patients with sepsis but no AKI.MethodsThe expression of miR-574-5p was regulated by cell transfection in HK-2 cells, and HK-2 cell viability was measured using the Cell Counting Kit-8. Serum miR-574-5p expression was analyzed using qRT-PCR. The predictive value of miR-574-5p for AKI onset was evaluated using the receiver operating characteristic curve and logistic regression analysis.ResultsThe overexpression of miR-574-5p promoted HK-2 cell viability. Fifty-eight sepsis patients developed AKI, who had significantly lower miR-574-5p expression. miR-574-5p expression was decreased with AKI stage increase and correlated with kidney injury biomarker and had relatively high accuracy to predict AKI occurrence from sepsis patients.ConclusionOverexpression of miR-574-5p in cultured HK-2 cells increases cell viability and knocked-down expression of miR-574-5p decreases cell viability. Consistently, septic patients with AKI were found to have less upregulation of miR-574-5p expression compared to septic patients without AKI. Thus, serum miR-574-5p may provide a novel biomarker for septic AKI.     

miR-134-5p靶向MRPL58调控乳腺癌细胞MCF7的凋亡研究

目的:探讨miR-134-5p靶向MRPL58调控乳腺癌细胞MCF7凋亡的潜在分子机制。方法:通过高通量测序检测正常乳腺上皮细胞MCF10A与乳腺癌细胞MCF7中的差异miRNA。在乳腺癌细胞MCF7中过表达差异倍数大于7的miRNA,检测其凋亡水平。通过miRDB在线分析miRNA潜在的靶标基因。通过过表达或敲低miRNA和荧光素酶报告实验确定miRNA的靶标基因。结果:正常乳腺上皮细胞MCF10A与乳腺癌细胞MCF7的总miRNA高通量测序结果发现,MCF10A细胞中miRNA比乳腺癌细胞MCF7表达量大于7倍的有30种。过表达上述miRNA后,miR-134-5p增强了乳腺癌细胞MCF7的凋亡水平(P<0.05)。敲低miR-134-5p后,乳腺癌细胞MCF7的凋亡水平下降(P<0.05)。miR-134-5p在癌旁组织中的表达水平高于乳腺癌组织(P<0.05)。过表达miR-134-5p后,KIAA0040,ZMAT5,RAB27A,TESMIN,MRPL58,ZFPM2,NUP98的表达水平下降(P<0.05)。敲低上述基因后,敲低MRPL58时乳腺癌细胞MCF7的凋亡水平上升(P<0.05)。过表达MRPL58后,乳腺癌细胞MCF7的凋亡水平下降。敲低miR-134-5p后,MRPL58的表达水平上升。过表达miR-134-5p后,MRPL58的表达水平下降。同时,miR-134-5p靶向MRPL58的3端非编码区(P<0.05)。同时敲低miR-134-5p和MRPL58后,乳腺癌细胞MCF7的凋亡水平没有显著改变(P>0.05)。同时过表达miR-134-5p和MRPL58后,乳腺癌细胞MCF7的凋亡水平没有显著改变(P>0.05)。结论:miR-134-5p通过靶向MRPL58 mRNA的3端非编码区以降低MRPL58的翻译水平,最终促进了乳腺癌细胞MCF7的凋亡。     

Overexpression of p18INK4C in LLC-PK1 cells increases resistance to cisplatin-induced apoptosis

Studies have demonstrated that cyclin-dependent kinase inhibitors (CDKI) that inhibit cell-cycle progression have a protective effect against acute kidney injury (AKI). Most studies have focused on the CIP/KIP family members of CDKI; only a few have explored the role of INK4 family members in AKI. Because INK4 family members block the G1-S transition, we postulated that they should have protective effects against AKI. The most conserved INK4 member is p18, so we selected it to explore its effects on cisplatin-induced renal cell injury. We overexpressed p18 in renal tubular epithelial cells (LLC-PK1) by transient transfection and investigated its effects on the cell cycle and proliferation. After transfection, cell injury was induced by cisplatin (100 μM) incubation for 24 h in a standard medium. The effect of p18 was assayed by assessing cell necrosis and apoptosis in transfected cells. The endoplasmic reticulum stress (ERS) pathway was evaluated to interpret the possible mechanism of p18 action in cisplatin-induced renal cell injury. Overexpression of p18 arrested cell cycle progression in the G1 phase and inhibited proliferation. Compared with vehicle transfection, p18 overexpression did not affect cisplatin-induced necrosis, but it reduced the percentage of apoptotic cells significantly. The severity of ERS induced by cisplatin was also decreased by p18 overexpression. P18 protects against cisplatin-induced renal cell injury. The mechanism of p18 protection may lie in its effect on the cell death pathway.     

Cytoprotective effects of hypoxia against cisplatin-induced tubular cell apoptosis: involvement of mitochondrial inhibition and p53 suppression

Hypoxia that is caused by vascular defects or disruption is commonly associated with renal diseases. During cisplatin nephrotoxicity, hypoxic regions are identified in the outer medulla and the renal cortex. However, the regulation of cisplatin injury by hypoxia is unclear. Previous work has demonstrated the cytoprotective effects of hypoxia against apoptotic injury. This study further examines the cytoprotective mechanisms in models of cisplatin-induced tubular cell apoptosis. In cultured renal tubular cells, 20 microM cisplatin induced approximately 60% apoptosis within 16 h. The rate of apoptosis was suppressed to < 20%, when the incubation was conducted under hypoxia (2% O2). Mitochondrial events of apoptosis, namely Bax accumulation and cytochrome c release, also were ameliorated. During cisplatin treatment, cell ATP was maintained in both normoxic and hypoxic cells. Hypoxic incubation lowered extracellular pH, but prevention of the pH decrease did not restore cisplatin-induced apoptosis. The cytoprotective effects of hypoxia also were independent of hypoxia-inducible factor 1 (HIF-1). Cobalt, as hypoxia, activated HIF-1 yet did not suppress cisplatin-induced apoptosis. Moreover, hypoxia suppressed cisplatin-induced apoptosis in HIF-1-deficient mouse embryonic stem cells and renal proximal tubular cells. Conversely, mitochondrial inhibitors, particularly inhibitors of respiration complex III (antimycin A and myxothiazol), mimicked hypoxia in apoptosis suppression. The effects of hypoxia and mitochondrial inhibitors were not additive. It is interesting that both hypoxia and complex III inhibitors ameliorated cisplatin-induced p53 activation. Therefore, the cytoprotective effects of hypoxia are independent of changes in cell ATP, pH, or HIF but may involve mitochondrial inhibition and the suppression of p53.     

MicroRNA-24 Antagonism Prevents Renal Ischemia Reperfusion Injury

Ischemia-reperfusion (I/R) injury of the kidney is a major cause of AKI. MicroRNAs (miRs) are powerful regulators of various diseases. We investigated the role of apoptosis-associated miR-24 in renal I/R injury. miR-24 was upregulated in the kidney after I/R injury of mice and in patients after kidney transplantation. Cell-sorting experiments revealed a specific miR-24 enrichment in renal endothelial and tubular epithelial cells after I/R induction. In vitro, anoxia/hypoxia induced an enrichment of miR-24 in endothelial and tubular epithelial cells. Transient overexpression of miR-24 alone induced apoptosis and altered functional parameters in these cells, whereas silencing of miR-24 ameliorated apoptotic responses and rescued functional parameters in hypoxic conditions. miR-24 effects were mediated through regulation of H2A histone family, member X, and heme oxygenase 1, which were experimentally validated as direct miR-24 targets through luciferase reporter assays. In vitro, adenoviral overexpression of miR-24 targets lacking miR-24 binding sites along with miR-24 precursors rescued various functional parameters in endothelial and tubular epithelial cells. In vivo, silencing of miR-24 in mice before I/R injury resulted in a significant improvement in survival and kidney function, a reduction of apoptosis, improved histologic tubular epithelial injury, and less infiltration of inflammatory cells. miR-24 also regulated heme oxygenase 1 and H2A histone family, member X, in vivo. Overall, these results indicate miR-24 promotes renal ischemic injury by stimulating apoptosis in endothelial and tubular epithelial cell. Therefore, miR-24 inhibition may be a promising future therapeutic option in the treatment of patients with ischemic AKI.     

DAP5 Ameliorates Cisplatin-Induced Apoptosis of Renal Tubular Cells

Background: Nephrotoxicity of cisplatin limits its clinical application. Cisplatin-induced acute renal tubular epithelial cell apoptosis is one of the major mechanisms of cisplatin nephrotoxicity. Here, the role and regulation of death-associated protein 5 (DAP5) in cisplatin-induced tubular cell apoptosis were investigated. Methods: After upregulation of DAP5 expression by plasmid transfection and downregulation of DAP5 expression by small interfering RNA in human kidney tubular epithelial cell line (HKC) cells, the degree of cell apoptosis was assessed by flow cytometric analysis. The expression of Bax and Bcl-2 proteins was detected by Western blot analysis. The relationship between the PI3K/Akt/mTOR signaling pathway and DAP5 was also evaluated. Results: During cisplatin-induced apoptosis in HKC cells, DAP5 underwent proteolytic fragmentation, yielding an 86-kDa species, DAP5/p86. Overexpression of DAP5/p97 and DAP5/p86 increased the translation of Bcl-2 and reduced the extent of cisplatin-induced apoptosis. Knockdown of DAP5 expression using small interfering RNA decreased the translation of Bcl-2 and increased the degree of apoptosis. Neither manipulation affected the expression of Bax. DAP5 expression was positively regulated by the PI3K/Akt/mTOR signaling pathway. Conclusion: Collectively, the results from the present study revealed a new role for DAP5 in cisplatin-induced apoptosis: DAP5/p97 and DAP5/p86 enhanced the translation of the anti-apoptotic protein Bcl-2 and inhibited cisplatin-induced apoptosis. The PI3K/Akt/mTOR signaling pathway may positively regulate the expression of DAP5.     

Insulin-like growth factor-1 sustains stem cell mediated renal repair

In mice with cisplatin-induced acute kidney injury, administration of bone marrow-derived mesenchymal stem cells (MSC) restores renal tubular structure and improves renal function, but the underlying mechanism is unclear. Here, we examined the process of kidney cell repair in co-culture experiments with MSC and cisplatin-injured proximal tubular epithelial cells (PTEC). Exposure of PTEC to cisplatin markedly reduced cell viability at 4 days, but co-culture with MSC provided a protective effect by promoting tubular cell proliferation. This effect was mediated by insulin-like growth factor-1 (IGF-1), highly expressed by MSC as mRNA and protein, since blocking the growth factor's function with a specific antibody attenuated cell proliferation of PTEC. Confirming this, knocking down IGF-1 expression in MSC by small interfering-RNA also resulted in a significant decrease in PTEC proliferation and increased apoptosis. Furthermore, in the murine model of cisplatin-induced kidney injury, administering IGF-1 gene-silenced MSC limited their protective effect on renal function and tubular structure. These findings indicate that MSC exert beneficial effects on tubular cell repair in acute kidney injury by producing the mitogenic and pro-survival factor IGF-1.     

Genistein protects the kidney from cisplatin-induced injury

Oxidative stress and inflammation contribute to the pathogenesis of cisplatin-induced nephrotoxicity. We found that genistein, a tyrosine kinase inhibitor with broad specificities, and which also has estrogen-like activity, had protective effects on cisplatin-induced renal injury in mice. Genistein significantly decreased reactive oxygen species production, the expression of intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 proteins, as well as the translocation of the p65 subunit of nuclear factor-kappaB into the nucleus and the infiltration of macrophages, all of which were increased in the kidney by cisplatin treatment. Genistein also decreased cisplatin-induced apoptosis by regulating p53 induction in kidney. Genistein significantly reduced reactive oxygen species production in cisplatin-treated normal human kidney HK-2 cells. These studies show that genistein or similar compounds might be useful in prevention of cisplatin-induced renal injury.     

MicroRNA-503 regulates high-glucose induced apoptosis of renal tubular epithelial cells by targeting Bcl-2

Objective To investigate the expression vibration of microRNA-503(miR-503) and its effect on target gene Bcl-2, caspase enzyme activity and apoptosis of human renal tubular epithelial cells (HK-2) induced by high glucose, and to clarify the pathogenesis of renal tubular injury induced by high glucose. Methods HK-2 cells were cultured in normal glucose group (NG), mannitol hypertonic control group (MA), and high glucose group (HG). The morphology of apoptotic cells was observed using inverted microscope. The expression of miR-503 was determined using real-time quantitative PCR. The apoptosis rate of HK-2 cells was detected by Annexin Ⅴ-FITC double dye using flow cytometry instrument. The expression of Bcl-2 and cleaved caspase-9 were detected by Western blotting. Results In the high glucose and mannitol groups HK-2 cell, an obviously increased apoptotic rate was observed under inverted microscope compared with normal glucose group (P＜0.05). MA and HG up-regulated miR-503 expression (P＜0.01), down-regulated anti-apoptotic protein Bcl-2 expression (P＜0.05) and up-regulated cleaved caspase-9 (P＜0.05). Conclusions The expression of miR-503 increases in HK-2 cells cultured by high glucose and mannitol. MiR-503 promotes apoptosis of HK-2 cells via activating mitochondrial apoptotic pathways and enhancing cleaved caspase-9 for Bcl-2 insufficiency. The tubular toxicity of high glucose is partly due to osmotic pressure. The miR-503 may be involved in diabetic tubular injury and may be a new therapeutic target of DN.     

Erythropoietin protects the kidney against the injury and dysfunction caused by ischemia-reperfusion

Erythropoietin (EPO) is upregulated by hypoxia and causes proliferation and differentiation of erythroid progenitors in the bone marrow through inhibition of apoptosis. EPO receptors are expressed in many tissues, including the kidney. Here it is shown that a single systemic administration of EPO either preischemia or just before reperfusion prevents ischemia-reperfusion injury in the rat kidney. Specifically, EPO (300 U/kg) reduced glomerular dysfunction and tubular injury (biochemical and histologic assessment) and prevented caspase-3, -8, and -9 activation in vivo and reduced apoptotic cell death. In human (HK-2) proximal tubule epithelial cells, EPO attenuated cell death in response to oxidative stress and serum starvation. EPO reduced DNA fragmentation and prevented caspase-3 activation, with upregulation of Bcl-X(L) and XIAP. The antiapoptotic effects of EPO were dependent on JAK2 signaling and the phosphorylation of Akt by phosphatidylinositol 3-kinase. These findings may have major implications in the treatment of acute renal tubular damage.