Hepatic Stellate Cell-derived IL-11 Exacerbates Liver Fibrosis via Interplay between HSCs and Macrophages

It has been a consensus that hepatic microenvironment composed by the non-parenchymal cells networks play a critical role during liver fibrogenesis, with the crosstalk between hepatic stellate cells (HSCs) and macrophages being of paramount importance. Interleukin 11(IL-11) has been implicated as a pro-fibrogenic cytokine, where its function in/between hepatocytes and HSCs has been revealed. But whether IL-11 participates in the interaction of HSCs and macrophages and related mechanism remains obscure. Our research demonstrates that HSC-derived IL-11 operates through a dual mechanism of autocrine activation and paracrine reprogramming to drive the fibrosis. AAV6-mediated IL-11 overexpression in the HSCs aggravated hepatic fibrosis induced by CCl₄ in C57/B6 mice, accompanied by a marked increase of M2 macrophages. Mechanistically, the autocrine signaling of IL-11 activated HSCs directly, potently enhancing the contractility, migration, and collagen production of HSCs through GP130-SFK-YAP pathway. Furthermore, IL-11 also functioned as a paracrine signal of HSCs activation that synergized with IL-4 to polarize macrophages into a profibrotic M2-like phenotype. This reprogramming was achieved through the coordinated activation of PI3K-mTOR signaling to promote TGF-β synthesis and STAT3 pathway to elevate chemokine levels. The necessity of macrophages in this process was proven when their depletion blunted the pro-fibrogenic effects of IL-11 overexpression. Consequently, therapeutic inhibition of IL-11 with a nanobody alleviated fibrosis and reversed macrophage polarization. Our findings proposed a self-amplifying loop where HSC-derived IL-11 directly activates fibrogenesis and simultaneously reprograms macrophages to create a feed-forward cycle that relentlessly drives disease progression.