MiR-155 is Involved in Renal Ischemia-Reperfusion Injury via Direct Targeting of FoxO3a and Regulating Renal Tubular Cell Pyroptosis

Abstract

Background/Aims: Ischemia/reperfusion injury (IRI) plays a crucial role in renal transplantation and can cause renal failure associated with pyroptosis, a pro-inflammatory-induced programmed cell death. Small endogenous non-coding RNAs have been shown to be involved in renal ischemia/reperfusion injury. This study was performed to investigate which miRNAs regulate pyroptosis in response to renal ischemia/reperfusion injury and determine the mechanism underlying this regulation. Methods: An in vivo rat model of renal IRI was established, and the serum and kidneys were harvested 24 h after reperfusion to assess renal function and histological changes. For the in vitro study, the cultured human renal proximal tubular cell line HK-2 was subjected to 24 h of hypoxia (5% CO₂, 1% O₂, and 94% N2) followed by 12 h of reoxygenation (5% CO₂, 21% O₂, and 74% N₂). The mRNA expression levels were analyzed by real-time PCR, and the protein expression levels were analyzed using Western blot, immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA). Bioinformatics analyses were applied to predict miR-155 targets, which were then confirmed by a luciferase reporter assay. Results: We found that the levels of pyroptosis-related proteins, including caspase-1, caspase-11, IL-1β and IL-18, were significantly increased after renal ischemia/reperfusion injury. Similarly, hypoxia-reoxygenation injury (HRI) also induced pyroptosis in HK2 cells. Furthermore, our study revealed that miR-155 expression was substantially increased in the renal tissues of IRI rats and in HRI HK2 cells. Up-regulation of miR-155 promoted HK2 cell pyroptosis in HRI; conversely, knockdown of miR-155 attenuated this process. To understand the signaling mechanisms underlying the pro-pyroptotic activity of miR-155, we found that exogenous expression of miR-155 up-regulated the expression of caspase-1 as well as the pro-inflammatory cytokines IL-1β and IL-18. Moreover, miR-155 directly repressed FoxO3a expression and its downstream protein apoptosis repressor with caspase recruitment domain (ARC). Conclusions: Our study proposes a new signaling pathway of miR-155/FoxO3a/ARC leading to renal pyroptosis under ischemia/reperfusion injury conditions.

Pioglitazone Confers Neuroprotection Against Ischemia-Induced Pyroptosis due to its Inhibitory Effects on HMGB-1/RAGE and Rac1/ROS Pathway by Activating PPAR-ɤ

“…Therefore, caspase-1 dependence is a definitive feature of pyroptosis that is characterized by the release of pro-inflammatory contents and plasma membrane rupture. Recent studies have demonstrated that pyroptosis mediated the death of renal and cardiac cells, leading to kidney and heart failure [11, 12, 43]. Our findings were consistent with those previously reported results.…”

“…Its activation by danger signals can mediate the maturation of capase-1, which results in the conversions of precursors of interleukin-1β and 18 into their active forms [10]. Recent researches further demonstrated that pyroptosis mediated the death of renal tubule epithelial cells after renal ischemia reperfusion injury [11, 12]. Therefore, it is of great significance to understand the mechanism that suppresses the inflammatory response and is responsible for the pyroptosis inhibition during the development and progression of cerebral ischemia injury.…”

Predictive Effects of Circulating miR-221, miR-130a and miR-155 for Coronary Heart Disease: A Multi-Ethnic Study in China

“…miRNAs are endogenous, small non-coding RNAs which are ∼22 nucleotides in length, and are involved in the post-transcriptional regulation of genes. Functional changes, including up-regulation and down-regulation of miRNAsare known to be involved in the pathogenesis of many diseases such as myocardial infarction [6-9], coronary artery calcification (CAC) [10], arrhythmia [11], cardiomyocyte hypertrophy [12-13], heart failure [14], renal ischemia-reperfusion injury [15], non-alcoholic fatty liver disease [16], tuberculosis [17], pancreatic ductal adenocarcinoma [18], and diabetes mellitus [19]. miRNAs are reported to not only exist within the cell but also reside stably in the extracellular compartments such as the circulation, which enables relatively simple detection of miRNAs as disease biomarkers.…”

Bone Marrow–Derived Mononuclear Cell Therapy Accelerates Renal Ischemia-Reperfusion Injury Recovery by Modulating Inflammatory, Antioxidant and Apoptotic Related Molecules

“…The improved function was associated with a reduced amount of tubular damage and decreased expression of pro-inflammatory molecules, including IL-18. IL-18 is well known to contribute to the worsening of renal injury induced by IRI, whereas TNF-α is an important mediator in the causation and perpetuation of previously observed kidney injury [56-58]. …”