Purinergic signaling is important in the activation and differentiation of macrophages, which play divergent roles in the pathophysiology of liver fibrosis. The ectonucleotidase CD39 is known to modulate the immunoregulatory phenotype of macrophages, but whether this specifically impacts cholestatic liver injury is unknown. Here, we investigated the role of macrophage-expressed CD39 on the development of biliary injury and fibrosis in a mouse model of sclerosing cholangitis. Myeloid-specific CD39-deficient mice (LysMCreCd39^fl/fl) were generated. Global CD39 null (Cd39^−/−), wild-type (WT), LysMCreCd39^fl/fl, and Cd39^fl/fl control mice were exposed to 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) to induce biliary fibrosis. Hepatic hydroxyproline levels, liver histology, immunohistochemistry, mRNA expression levels, and serum biochemistry were then assessed. Following 3 weeks of DDC-feeding, Cd39^−/− mice exhibited more severe fibrosis, when compared to WT mice as reflected by morphology and increased liver collagen content. Myeloid-specific CD39 deletion in LysMCreCd39^fl/fl mice recapitulated the phenotype of global Cd39^−/−, after exposure to DDC, and resulted in similar worsening of liver fibrosis when compared to Cd39^fl/fl control animals. Further, DDC-treated LysMCreCd39^fl/fl mice exhibited elevated serum levels of transaminases and total bilirubin, as well as increased hepatic expression of the profibrogenic genes Tgf-β1, Tnf-α, and α-Sma. However, no clear differences were observed in the expression of macrophage-elaborated specific cytokines between LysMCreCd39^fl/fl and Cd39^fl/fl animals subjected to biliary injury. Our results in the DDC-induced biliary type liver fibrosis model suggest that loss of CD39 expression on myeloid cells largely accounts for the exacerbated sclerosing cholangitis in global CD39 knockouts. These findings indicate that macrophage expressed CD39 protects from biliary liver injury and fibrosis and support a potential therapeutic target for human hepatobiliary diseases.

中文翻译：

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在硬化性胆管炎的小鼠模型中，巨噬细胞中ENTPD1 / CD39的选择性缺失加剧了胆汁纤维化。

嘌呤能信号在巨噬细胞的激活和分化中很重要，而巨噬细胞在肝纤维化的病理生理中起着不同的作用。已知外切核苷酸酶CD39可调节巨噬细胞的免疫调节表型，但尚不清楚其是否特异性影响胆汁淤积性肝损伤。在这里，我们调查了硬化性胆管炎的小鼠模型中巨噬细胞表达的CD39在胆道损伤和纤维化发展中的作用。产生了髓样特异性CD39缺陷小鼠（LysMCre Cd39 ^{fl / fl}）。全局CD39 null（Cd39 ^-/-），野生型（WT），LysMCre Cd39 ^{fl / fl}和Cd39 ^{fl / fl}对照小鼠暴露于3，5-二乙氧基羰基-1，4-二氢可力丁（DDC）以诱导胆汁纤维化。然后评估肝羟脯氨酸水平，肝脏组织学，免疫组织化学，mRNA表达水平和血清生物化学。用DDC喂养3周后，与WT小鼠相比，Cd39 ^-/-小鼠表现出更严重的纤维化，这是通过形态学和肝胶原含量增加所反映的。LysMCre Cd39 ^{fl / fl}小鼠的髓样特异性CD39缺失重现了暴露于DDC后的整体Cd39 ^-/-表型，与Cd39 ^{fl / fl}对照动物相比，导致肝纤维化的恶化。此外，DDC处理的LysMCre Cd39^{fl / fl}小鼠的血清转氨酶和总胆红素水平升高，并且肝纤维化原基因Tgf-β1， Tnf-α和α-Sma的表达增加。然而，在LysMCre Cd39 ^{fl / fl}和Cd39 ^{fl / fl}之间巨噬细胞修饰的特定细胞因子的表达中没有观察到明显差异。动物受到胆道伤害。我们在DDC诱导的胆汁型肝纤维化模型中的结果表明，髓样细胞上CD39表达的丧失在很大程度上导致了总体CD39基因敲除中硬化性硬化性胆管炎的发生。这些发现表明巨噬细胞表达的CD39保护免受胆道肝损伤和纤维化，并支持人类肝胆疾病的潜在治疗目标。