Hepatic stellate cell-derived microfibrillar-associated protein 2 prevents liver fibrosis by regulating extracellular matrix and inflammation

Microfibrillar-associated protein 2 (MFAP-2) is a crucial component of the extracellular matrix (ECM) microfibrils, yet its role in liver fibrosis remains elusive. Methods: Human tissue arrays and mouse models of fibrosis progression and resolution were used to investigate MFAP-2 expression patterns. Mfap2 deficiency (Mfap2 ^-/-) or overexpression (ovMfap2) mice were subjected to carbon tetrachloride (CCl₄) injection or bile duct ligation (BDL) to induce liver fibrosis. Histological, biochemical, bulk, or single-cell RNA-sequencing (scRNA-seq), proteomics to analyze the matrisome, and in vitro studies were conducted. Results: MFAP-2 was predominantly enriched in activated hepatic stellate cells (HSCs) and upregulated in advanced liver fibrosis. Although Mfap2 ablation had minimal impact on collagen deposition during CCl₄ injection, it significantly delayed fibrosis regression after CCl₄ cessation. The delayed fibrosis regression due to Mfap2 deficiency was likely linked to aggravated intrahepatic inflammation, ECM stabilization, and activated focal adhesion signaling in HSCs. Mechanically, inhibiting HSC-derived Mfap2 enhanced HSC interactions and increased matrisome protein production, while reducing the interaction between HSCs and liver-resident macrophages by decreasing macrophage migration inhibitory factor secretion from HSCs. Additionally, we validated the role of Mfap2 deletion in liver fibrosis using the BDL mouse model, demonstrating a more pronounced effect on fibrosis progression. Adeno-associated virus vector (serotype 6)-mediated Mfap2 overexpression in HSCs conferred protection against liver fibrosis in both models. Conclusion: This study reveals the compensatory protective effects of HSC-derived MFAP-2 on liver fibrosis and its underlying mechanisms. Enhancing MFAP-2 in HSCs may therefore benefit patients with liver fibrosis.