Miyagawa-Hayashino Aya, Imura Tetsuya, Takezawa Toshiaki, Hirai Maki, Shibata Saya, Ogi Hiroshi, Tsujikawa Takahiro, Konishi Eiichi
Department of Surgical Pathology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Faculty of Pharmacy, Chiba Institute of Science, Chiba, Japan.
PLoS One. 2025 Jan 24;20(1):e0317568. doi: 10.1371/journal.pone.0317568. eCollection 2025.
Immunologic bile duct destruction is a pathogenic condition associated with vanishing bile duct syndrome (VBDS) after liver transplantation and hematopoietic stem-cell transplantation. As the bile acid receptor sphingosine 1-phosphate receptor 2 (S1PR2) plays a critical role in recruitment of bone marrow-derived monocytes/macrophages to sites of cholestatic liver injury, S1PR2 expression was examined using cultured macrophages and patient tissues. Bile canaliculi destruction precedes intrahepatic ductopenia; therefore, we focused on hepatocyte S1PR2 and the downstream RhoA/Rho kinase 1 (ROCK1) signaling pathway and bile canaliculi alterations using three-dimensional hepatocyte culture models that form obvious bile canaliculus-like networks. Multiplex immunohistochemistry revealed increased numbers of S1PR2+CD45+CD68+FCN1+ inflammatory macrophages and S1PR2+CD45+CD68+MARCO+ Kupffer cells in liver tissues showing ductopenia due to graft-versus-host disease and rejection post-liver transplant compared with normal liver. Macrophage expression of proinflammatory cytokines, including MCP1, was reduced following S1PR2 inhibition. Taurocholic acid and S1P2 agonist induced hepatocyte S1PR2 and reduced RhoA/ROCK1 expression, resulting in bile canaliculi dilatation. S1PR2 inhibition reversed the effect on RhoA/ROCK1 expression, resulting in maintenance of bile canaliculi through myosin light chain 2 (MLC2) phosphorylation. Activation of S1PR2 on macrophages and S1PR2 on hepatocytes may disrupt bile canaliculi dynamics in VBDS under regulation by RhoA/ROCK1 through MLC2 phosphorylation.
免疫性胆管破坏是一种与肝移植和造血干细胞移植后出现的胆管消失综合征（VBDS）相关的致病状态。由于胆汁酸受体鞘氨醇-1-磷酸受体2（S1PR2）在骨髓来源的单核细胞/巨噬细胞募集至胆汁淤积性肝损伤部位的过程中起关键作用，因此利用培养的巨噬细胞和患者组织对S1PR2表达进行了检测。胆小管破坏先于肝内胆管减少；因此，我们利用形成明显胆小管样网络的三维肝细胞培养模型，重点研究了肝细胞S1PR2及下游RhoA/Rho激酶1（ROCK1）信号通路和胆小管改变。多重免疫组化显示，与正常肝脏相比，因移植物抗宿主病和肝移植后排斥反应导致胆管减少的肝组织中，S1PR2+CD45+CD68+FCN1+炎性巨噬细胞和S1PR2+CD45+CD68+MARCO+库普弗细胞数量增加。S1PR2抑制后，包括MCP1在内的促炎细胞因子的巨噬细胞表达降低。牛磺胆酸和S1P2激动剂诱导肝细胞S1PR2表达并降低RhoA/ROCK1表达，导致胆小管扩张。S1PR2抑制可逆转对RhoA/ROCK1表达的影响，通过肌球蛋白轻链2（MLC2）磷酸化维持胆小管结构。巨噬细胞上S1PR2的激活和肝细胞上S1PR2的激活可能会在RhoA/ROCK1通过MLC2磷酸化的调控下破坏VBDS中胆小管的动态变化。
