肝巨噬细胞（Mø）在肝纤维化中有双重作用，但关键调控分子不清。我们发现MANF在纤维化肝脏高表达，重组人MANF抑制鼠肝纤维化，增加M2型Mø数；单核/Mø特异性MANF敲除（MKO）增加肝脏M1型Mø数和促炎因子水平；重组人MANF进入Mø受TLR4调节。推测肝脏炎症上调Mø表达和分泌MANF，通过调节Mø的TLR4/NF-B信号通路改变Mø表型和功能，抑制肝星状细胞（HSC）活化和肝纤维化。拟研究内容：1.观察人肝炎和鼠纤维化肝组织MANF表达与Mø异质性、肝纤维化关系；2.观察MANF敲低或过表达或给予重组人MANF对Mø表型和功能的影响；3.采用MKO鼠研究MANF缺失对Mø异质性、HSC活化及肝纤维化影响；4.阐明MANF通过TLR4/NF-B信号通路抑制肝纤维化机制。该研究将阐释MANF调控Mø可塑性抑制肝纤维化的新机制，也为将MANF作为药物靶点或靶点药物的临床实践奠定基础。

Hepatic macrophages have been proved to play a dual role of pro-inflammation and anti-inflammation in the progression of liver fibrosis due to their heterogeneity, but there are still insufficient evidences to demonstrate the key factors that involved in the heterogeneity modulation. Our previous studies have showed that mesencephalicastrocyte-derived neurotrophic factor (MANF) was up-regulated in macrophages in the fibrosic liver tissues. Recombinant human MANF inhibited CCl4-induced mice liver fibrosis and increased the number of M2 macrophages. On the contrary, mono-macrophage-specific MANF knockout increased the number of M1 macrophages and the production of pro-inflammatory factors. Therefore, we hypothesized that chronic inflammation promotes the high expression of MANF in Kupffer cells and monocyte-derived hepatic macrophages that promotes transformation of macrophages subpopulation and initiates hepatic stellate cells activation and liver fibrosis via regulation of TLR4/NF-B signal pathway. To address this hypothesis, we will do as follows: (1) We will examine MANF expression in human hepatic tissues with hepatitis B infection and mouse hepatic tissues with CCl4-induce hepatic fibrosis. Meanwhile, the correlation between MANF expression and hepatic macrophages phenotypes and function and hepatic fibrosis degree will be analyzed; (2) We will use the stable cell lines in that MANF was knocked down or over-expressed or use the cells treated with recombinant human MANF to study the regulation of MANF in hepatic macrophages subpopulation and function under environmental stimuli (inflammation, ER stress, etc); (3) We have established the monocyte/macrophage-specific MANF knock-out mice. The impact of MANF on hepatic macrophages subpopulation/function and hepatic fibrosis will be explored by using the mice model. (4) We will further explore the underlying mechanisms by which MANF regulates macrophages differentiation and hepatic stellate cells function via TLR4/NF-kappa B signal pathway. This study may uncover a novel mechanism that MANF contributes to the heterogeneity of hepatic macrophages, which may be helpful for understanding the pathogenesis of hepatic fibrosis and the function of MANF in tissue-specific immunoregulation and shed a light on the further study on developing new therapeutic agents for chronic liver injury.