Mesenchymal stem cell-derived exosomes protect against liver fibrosis via delivering miR-148a to target KLF6/STAT3 pathway in macrophages

Abstract

Background Despite emerging evidence on the therapeutic potential of mesenchymal stem cells (MSCs) for liver fibrosis, the underlying mechanisms remain unclear. At present, MSC-derived exosomes (MSC-EXOs) are widely accepted as crucial messengers for intercellular communication. This study aimed to explore the therapeutic effects of MSC-EXOs on liver fibrosis and identify the mechanisms underlying the action of MSC-EXOs. Methods Carbon tetrachloride was used to induce a liver fibrosis model, which was intravenously administered with MSCs or MSC-EXOs to assess treatment efficacy. The resulting histopathology, fibrosis degree, inflammation and macrophage polarization were analyzed. RAW264.7 and BMDM cells were used to explore the regulatory effects of MSC-EXOs on macrophage polarization. Then, the critical miRNA mediating the therapeutic effects of MSC-EXOs was screened via RNA sequencing and validated experimentally. Furthermore, the target mRNA and downstream signaling pathways were elucidated by luciferase reporter assay, bioinformatics analysis and western blot. Results MSCs alleviated liver fibrosis largely depended on their secreted exosomes, which were visualized to circulate into liver after transplantation. In addition, MSC-EXOs were found to modulate macrophage phenotype to regulate inflammatory microenvironment in liver and repair the injury. Mechanically, RNA-sequencing illustrates that miR-148a, enriched in the MSC-EXOs, targets Kruppel-like factor 6 (KLF6) to suppress pro-inflammatory macrophages and promote anti-inflammatory macrophages by inhibiting the STAT3 pathway. Administration of miR-148a-enriched MSC-EXOs or miR-148a agomir shows potent ameliorative effects on liver fibrosis. Conclusions These findings suggest that MSC-EXOs protect against liver fibrosis via delivering miR-148a that regulates intrahepatic macrophage functions through KLF6/STAT3 signaling and provide a potential therapeutic target for liver fibrosis.

Exosomes in liver fibrosis: The role of modulating hepatic stellate cells and immune cells, and prospects for clinical applications

“…found that MSC-EXO could ameliorate LF by promoting the shift of macrophages from the M1 pro-inflammatory phenotype to the M2 anti-inflammatory phenotype. This effect is attributed to the ability of miR-148a delivered by MSC-EXO to regulate KLF6/STAT3 signaling ( 72 ). Bone marrow mesenchymal stem cell-derived exosome(BMSC-EXO) have been demonstrated to be more effective than BMSC in alleviating LF It has been reported that BMSC-EXO can inhibit HSC activation by inhibiting the Wnt/β-catenin pathway, thereby alleviating CCl4-induced LF in rats ( 73 ).…”

MicroRNA: role in macrophage polarization and the pathogenesis of the liver fibrosis

“…MiR-155 knockdown in KCs could positively regulate the immunosuppressive function of KCs and prolong the survival of liver allografts. MiR-148a-enriched mesenchymal stem cell-derived exosomes (MSC-EXOs) modulated macrophages towards the anti-inflammatory phenotype and exerted ameliorative effects on liver fibrosis ( 48 ). In a mouse model of Schistosomiasis japonicum , miR-130a-3p promoted the differentiation of macrophages toward the Ly6Clo phenotype and alleviated liver granulomatous inflammation ( 49 ).…”

Extracellular vesicles in fatty liver disease and steatohepatitis: Role as biomarkers and therapeutic targets

“…MSC‐EVs modulate macrophage phenotype by inhibiting M1 macrophage activation, which is induced by the lipopolysaccharide (LPS)‐TLR4 pathway, with consequent production of inflammatory cytokines including TNF‐α, IL‐1β and IL‐6 in a NASH rat model 51 . MSC‐EV‐encapsulated miR‐148a modulates macrophage polarization that suppresses pro‐inflammatory macrophages and promotes anti‐inflammatory macrophages by inhibiting the Kruppel‐like factor 6/STAT3 pathway, resulting in a protection of liver fibrosis using a liver fibrosis mouse model 52 . Furthermore, MSC‐EVs recruit anti‐inflammatory macrophages, CD11b + F4/80 + Ly6c low , to the liver of NASH mice to eliminate dead cells, pathogens and cell debris via the high phagocytic activity of F4/80 + macrophages 53 .…”

“…51 MSC-EV-encapsulated miR-148a modulates macrophage polarization that suppresses pro-inflammatory macrophages and promotes anti-inflammatory macrophages by inhibiting the Kruppel-like factor 6/STAT3 pathway, resulting in a protection of liver fibrosis using a liver fibrosis mouse model. 52 Furthermore, MSC-EVs recruit antiinflammatory macrophages, CD11b + F4/80 + Ly6c low , to the liver of NASH mice to eliminate dead cells, pathogens and cell debris via the high phagocytic activity of F4/80 + macrophages. 53 MSC-EVs inhibit HSC activation, including a reduction in α-smooth muscle actin (α-SMA) and collagen 1, via the suppression of the Wnt/β-catenin pathway in a rat liver fibrosis model.…”