Upregulation of Mitochondrial Transcription Factor A Promotes the Repairment of Renal Tubular Epithelial Cells in Sepsis by Inhibiting Reactive Oxygen Species-Mediated Toll-Like Receptor 4/p38MAPK Signaling

KLF13 overexpression protects sepsis-induced myocardial injury and LPS-induced inflammation and apoptosis

Sepsis remains a worldwide public health problem. This study aims to explore the role and mechanism of transcriptional factors (TFs) in sepsis-induced myocardial injury. Firstly, TF KLF13 was selected to explore its role in sepsis-induced myocardial injury. The caecal ligation and puncture (CLP) -induced sepsis mouse model was established and the septic mice were examined using standard histopathological methods. KLF13 expression was detected in the septic mouse heart and was also seen in a lipoploysaccharide (LPS) -induced cellular inflammation model. To explore this further both pro-apoptotic cleaved-caspase3/caspase3 and Bax levels and anti-apoptotic Bcl2 levels were examined, also in both models, In addition inflammatory cytokine (IL-1β, TNF-α, IL-8 and MCP-1) production and IκB-α protein level and p65 phosphorylation were examined in both septic mice and LPS-induced cells. Thus three parameters - cardiomyocyte apoptosis, inflammatory response and NF-κB pathway activation were evaluated under similar conditions. The septic mice showed significant oedema, disordered myofilament arrangement and degradation and necrosis to varying degrees in the myocardial cells. KLF13 was downregulated in both the septic mouse heart and the LPS-induced cellular inflammation model. Furthermore, both models showed abnormally increased cardiomyocyte apoptosis (increased cleaved-caspase3/caspase and Bax protein levels and decreased Bcl2 level), elevated inflammation (increased production of inflammatory cytokines) and the activated NF-κB pathway (increased p65 phosphorylation and decreased IκB-α protein level). KLF13 overexpression notably ameliorated sepsis-induced myocardial injury in vivo and in vitro. KLF13 overexpression protected against sepsis-induced myocardial injury and LPS-induced cellular inflammation and apoptosis via inhibiting the inflammatory pathways (especially NF-κB signalling) and cardiomyocyte apoptosis.

Prohibitin Protects Pulmonary Microvascular Endothelial Cells Against Cigarette Smoke Extract-Induced Cell Apoptosis and Inflammation

Background

Prohibitin has been identified to play roles in cell survival and apoptosis. Here, this study aimed to clarify the role of prohibitin in cigarette smoke extract (CSE)-induced endothelial cell apoptosis.

Methods

The protein level of prohibitin was assessed by Western blot in lung tissues from emphysema and control mice. CSE-induced human pulmonary microvascular endothelial cells (hPMECs) were applied to mimic smoke-related cell apoptosis in vitro. Prohibitin was overexpressed in hPMECs with or without CSE. Mitochondrial function was analyzed by JC-1 staining and ATP assay kits. Oxidative stress was assessed by flow cytometry, fluorescence staining and immunocytochemistry. Apoptosis was analyzed by flow cytometry, Western blot and caspase-3 activity assays. In addition, the expression of inflammatory markers was assessed by Western blot and real-time polymerase chain reaction (PCR). The secretion of inflammatory cytokines was measured by ELISA.

Results

Prohibitin was downregulated in emphysema mouse tissues compared with control experiments. Consistently, CSE inhibited both the protein and RNA levels of prohibitin in hPMECs in a dose-dependent manner. Gain-of-function experiments indicated that CSE induced collapse of mitochondrial membrane potential (MMP) and loss of ATP, while prohibitin improved mitochondrial function. CSE induced robust ROS production and oxidative DNA damage, while prohibitin decreased this damage. Upregulation of prohibitin protected the apoptosis of hPMECs from CSE. Overexpression of prohibitin significantly reduced the levels of the main proinflammatory cytokines. Finally, prohibitin inhibited nuclear factor-kappa B (NF-κB) p65 accumulation and IκBα degradation induced by CSE.

Conclusion

The current findings suggest that CSE-mediated mitochondrial dysfunction, oxidative stress, cell apoptosis and inflammation in hPMECs were reduced by overexpression of prohibitin. We identified prohibitin as a novel regulator of endothelial cell apoptosis and survival in the context of CSE exposure.

miR-129-5p alleviates LPS-induced acute kidney injury via targeting HMGB1/TLRs/NF-kappaB pathway

INTRODUCTION

The present study aimed to investigate whether miR-129-5p can regulate high-mobility group box protein 1 (HMGB1)-modulated TLRs/NF-kappaB inflammatory pathway that contributed to lipopolysaccharide (LPS)-induced podocyte apoptosis and acutekidneyinjury (AKI).

MATERIAL AND METHODS

In vitro and in vivo models of sepsis were simulated using LPS-administrated podocytes and mice, respectively. The effects of LPS, mR-129-5p mimics and short hairpin RNA of HMGB1 (sh-HMGB1) on podocyte apoptosis were monitored using TUNEL staining. Protein expression was measured using western blotting. Survival outcomes were analyzed in septic mice with agomir-mR-129-5p administration.

RESULTS

We observed that stimulation of podocytes with LPS significantly inhibits the expression of miR-129-5p, and overexpression of miR-129-5p protects against LPS-induced podocyte damage, over-activation of inflammatory response and apoptosis. In a mouse model, agomir-miR-129-5p administration significantly improves the survival outcomes in septic mice and LPS-induced AKI. Mechanically, LPS-induced the elevation of HMGB1, TLR2, TLR4 and nuclear NF-κB protein expression in vitro and in vivo are restrained by the overexpression of miR-129-5p.

CONCLUSIONS

Overexpression of miR-129-5p protects against LPS-induced podocyte apoptosis, inflammation and AKI in vivo and in vitro models of sepsis. The underlying molecular mechanism is mediated via attenuating HMGB1/TLRs/NF-κB signaling axis modulated inflammatory response.

Knockdown of LncRNA DLX6-AS1 inhibits HK-2 cell pyroptosis via regulating miR-223-3p/NLRP3 pathway in lipopolysaccharide-induced acute kidney injury

Sepsis-induced acute kidney injury (AKI) represents a severe medical complication. Recently, there is growing evidence indicating the regulatory role of long non-coding RNAs (lncRNAs) in AKI pathophysiology. The present study investigated lncRNA DLX6 antisense RNA 1 (DLX6-AS1) expression in septic AKI patients and to decipher the relevant mechanisms underlying DLX6-AS1-mediated HK-2 cell pyroptosis in lipopolysaccharide (LPS)-induced AKI. The results revealed that DLX6-AS1 was up-regulated in the serum from septic AKI patients. DLX6-AS1 expression were positively associated with the creatinine levels in the serum from the septic AKI patients. In vitro studies showed that LPS induced cytotoxicity and enhanced DLX6-AS1 expression of HK-2 cells; increased NLR family pyrin domain containing 3 (NLRP3), interleukin (IL)-1β and IL-18 expression. DLX6-AS1 overexpression promoted cytotoxicity and pyroptosis of HK-2 cells; while DLX6-AS1 knockdown counteracted the LPS-induced cytotoxicity and pyroptosis of HK-2 cells. More importantly, DLX6-AS1 sponged miR-223-3p resulting in repression of miR-223-3p expression in HK-2 cells. MiR-223-3p could bind to the 3' untranslated region of NLRP3, which results in the suppressed NLRP3 expression of HK-2 cells. Further rescue experiments showed that enhanced miR-223-3p expression partially reversed the cytotoxicity and pyroptosis of HK-2 cells upon LPS stimulation or with DLX6-AS1 overexpression. Conclusively, this study identified enhanced DLX6-AS1 expression in the serum from AKI patients. Further mechanistic findings deciphered that DLX6-AS1 mediated LPS-mediated cytotoxicity and pyroptosis in HK-2 via miR-223-3p/NLRP3 axis.