Inhibition of microRNA-376b Protects Against Renal Interstitial Fibrosis via Inducing Macrophage Autophagy by Upregulating Atg5 in Mice with Chronic Kidney Disease

Abstract

Background/Aims: Renal interstitial fibrosis (RIF) is a common feature that facilitates the progression of chronic kidney disease (CKD), and emerging lines of evidence suggest that microRNA-376b (miR-376b) is capable of promoting RIF. In this study, we examined collagen deposition in kidney tissues, the autophagy and mitochondrial reactive oxygen species (ROS) of macrophages, and the apoptosis of kidney fibroblasts (KFBs) after the promotion or suppression of endogenous miR-376b in cultured macrophages and renal fibroblasts obtained from mice with CKD. Methods: FVB/N mice were prepared to establish a CKD model. A target prediction program and luciferase activity determination were used to confirm that autophagy-related gene 5 (Atg5) was a direct target of miR-376b. Macrophages and KFBs were isolated after the treatment to study the mechanisms and functions of miR-376b in relation to Atg5 in CKD. The autophagy level was determined, and KFB proliferation and apoptosis were assessed through MTT and EdU assays and flow cytometry, respectively. Results: Atg5 was confirmed as a direct target of miR-376b. miR-376b and Atg5 exhibited high and low expression in kidney tissues from mice with CKD. The mice treated with a miR-376b inhibitor exhibited reduced collagen deposition, suppressed interstitial fibrosis, a higher level of autophagy, higher ROS production, enhanced apoptosis, and inhibited proliferation of KFBs, which suggested that the downregulation of miR-376b could exert beneficial effects on CKD through Atg5. Conclusion: miR-376b downregulation promotes macrophage autophagy to relieve RIF by negatively regulating Atg5 in mice with CKD. Thus, miR-376b might represent a potential focus of future investigations on treatments for CKD.

microRNA Crosstalk Influences Epithelial-to-Mesenchymal, Endothelial-to-Mesenchymal, and Macrophage-to-Mesenchymal Transitions in the Kidney

“…Differential miRNA expression data suggest a role of altered miRNA in the pathogenesis of kidney disease (Bhatt et al, 2011; Lorenzen et al, 2011; Zhong et al, 2011; Chau et al, 2012; Chung and Lan, 2015; Van Der Hauwaert et al, 2015; Schauerte et al, 2017; Zhang et al, 2017; Hajarnis et al, 2018; Thomas et al, 2018; Xi et al, 2018; Yang et al, 2018; Zheng et al, 2018; Fujii et al, 2019; Liu et al, 2019a; Liu et al, 2019c; Zhao et al, 2019). The term fibromiR has been suggested for those miRNAs that regulate fibro-proliferative diseases (Pottier et al, 2014).…”

Incremental load training improves renal fibrosis by regulating the TGF‑β1/TAK1/MKK3/p38MAPK signaling pathway and inducing the activation of autophagy in aged mice

“…Autophagy is a conserved process of cell component degradation and cycling depending on lysosomes that eliminates damaged organelles and abnormal proteins to maintain a stable intracellular environmental and stress response (36). To date, numerous basic and clinical studies have reported on the critical function of autophagy in the occurrence and development of fibrosis (37,38). Ceylan-Isik et al (37) indicated that aging-induced cardiac interstitial fibrosis is closely linked to the decrease of autophagic activity.…”

Regulation of autophagy by miRNAs in human diseases

“…Administration of Atg5 shRNA, with and without miR-376b inhibitor, also validates this finding. This study, which also shows increased ROS in mice treated with miR-376b inhibitor, highlights the importance of miRNAs in the crosstalk between different pathways of programmed cell death (autophagy, apoptosis) in the pathogenesis of the end-stage renal disease (ESRD) [ 90 ]. Renal tubulointerstitial fibrosis is also an essential feature of diabetic nephropathy (DN), a pathological condition already discussed above in the context of microRNAs regulating autophagy.…”