IGF2-NR4A2 Signaling Regulates Macrophage Subtypes to Attenuate Liver Cirrhosis

BACKGROUND AND AIMS: Liver cirrhosis can lead to liver failure and eventually death. Macrophages are the main contributors to cirrhosis and have a bidirectional role in regulating matrix deposition and degradation. Macrophage-based cell therapy has been developed as an alternative to liver transplantation. However, there is insufficient evidence regarding its safety and efficacy. In this study, we aimed to explore the effect of combining insulin-like growth factor 2 (IGF2) with bone marrow-derived macrophages (BMDMs) to treat mice with liver cirrhosis. METHODS: We assessed liver inflammation, fibrosis regression, liver function, and liver regeneration in mice with CCl(4)-induced cirrhosis and treated with BMDM only or IGF2 + BMDM. We performed in vitro experiments in which activated hepatic stellate cells (HSCs) were co-cultured with macrophages in the presence or absence of IGF2. The polarity of macrophages and the degree of inhibition of HSCs were examined. The effect of IGF2 on macrophages was also verified by the overexpression of IGF2. RESULTS: Combining IGF2 with BMDM reduced liver inflammation and fibrosis and increased hepatocyte proliferation. Combining IGF2 with BMDM was more effective than using BMDM alone. In vitro experiments demonstrated that IGF2 inhibited HSCs activation by upregulating NR4A2 to promote the anti-inflammatory macrophages phenotype. IGF2 also increased the synthesis of matrix metalloproteinases (MMPs) by macrophages, which may explain why administering IGF2 combined with BMDM was more effective than administering BMDM only. CONCLUSIONS: Our study provides a theoretical basis for the future use of BMDM-based cell therapy to treat liver cirrhosis.