Sharma Akanksha, Wang Jiang, Gandhi Chandrashekhar R
Cincinnati Veterans Administration Medical Center, Cincinnati, Ohio, USA.
Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
J Cell Physiol. 2023 Jul;238(7):1530-1541. doi: 10.1002/jcp.31030. Epub 2023 Apr 26.
Binding of lipopolysaccharide (LPS) to CD14 is required for its cellular effects via TLR4. A role of LPS/TLR4-mediated signaling in activated hepatic stellate cells (aHSCs), the major fibrogenic cells, in liver fibrosis has been reported. We investigated effects of LPS on carbon tetrachloride (CCl4)-induced fibrosis in CD14-knockout (KO) mice in vivo, and culture-activated HSCs in vitro. CCl4 (biweekly; 4 weeks)-treated wild type (WT) and CD14-KO mice were challenged with single LPS administration for 24 h. Liver injury, inflammation and fibrosis were determined. Culture-activated HSCs from WT or CD14-KO mice were stimulated with LPS. Parameters of fibrogenic activity (expression of collagen1a1 [Col1a1], α-smooth muscle actin [αSMA] and TGFβ1) and inflammatory cytokines/chemokines were measured. CCl4 treatment caused similar liver injury and fibrosis in WT and CD14-KO mice. LPS increased liver injury and inflammation similarly in CCl4-treated WT and CD14-KO mice, but downregulated Timp1 and upregulated Mmp13. LPS elicited similar NFκB activation and inflammatory response in WT and CD14-KO aHSCs. LPS similarly downregulated Acta2 (encodes αSMA), Pdgfrb, Col1a1 and Mmp13 expression but did not affect Timp1 expression in WT and CD14-KO aHSCs. LPS did not alter Tgfb1 but increased expression of decorin (Dcn) (inhibitor of TGFβ1) expression in WT and CD14-KO aHSCs. The results indicate that the effects of LPS on HSCs are CD14-independent, and CD14 is not required for hepatic fibrosis. LPS-induced down-modulation of fibrogenic markers in aHSCs is also CD14-independent.
脂多糖（LPS）与CD14结合是其通过Toll样受体4（TLR4）产生细胞效应所必需的。据报道，LPS/TLR4介导的信号传导在肝纤维化中主要的致纤维化细胞——活化肝星状细胞（aHSCs）中发挥作用。我们在体内研究了LPS对四氯化碳（CCl4）诱导的CD14基因敲除（KO）小鼠肝纤维化的影响，并在体外研究了其对培养的活化肝星状细胞的影响。每两周一次（共4周）给予野生型（WT）和CD14-KO小鼠CCl4处理，之后单次给予LPS刺激24小时，测定肝损伤、炎症和纤维化情况。用LPS刺激来自WT或CD14-KO小鼠的培养活化肝星状细胞，检测纤维化活性参数（I型胶原α1[Col1a1]、α平滑肌肌动蛋白[αSMA]和转化生长因子β1[TGFβ1]的表达）以及炎性细胞因子/趋化因子。CCl4处理在WT和CD14-KO小鼠中引起相似的肝损伤和纤维化。LPS在CCl4处理的WT和CD14-KO小鼠中同样增加了肝损伤和炎症，但下调了金属蛋白酶组织抑制因子1（Timp1）并上调了基质金属蛋白酶13（Mmp13）。LPS在WT和CD14-KO aHSCs中引发相似的核因子κB（NFκB）激活和炎症反应。LPS同样下调了肌动蛋白α2（Acta2，编码αSMA）、血小板衍生生长因子受体β（Pdgfrb）、Col1a1和Mmp13的表达，但不影响WT和CD14-KO aHSCs中Timp1的表达。LPS不改变Tgfβ1，但增加了WT和CD14-KO aHSCs中核心蛋白聚糖（Dcn，TGFβ1的抑制剂）的表达。结果表明，LPS对肝星状细胞的作用不依赖于CD14，肝纤维化也不需要CD14。LPS诱导的aHSCs中纤维化标志物的下调同样不依赖于CD14。
