Purpose: To explore the possible mechanism of the rapid progression of liver fibrosis in BA (biliary atresia) through multi-omics methods.
Method: BA liver tissues with different degrees of liver fibrosis (n=4), liver tissues of choledochal cyst (n=2), and liver tissues of the NC (normal control) group (n=2) were selected. Single-cell RNA sequencing, spatial transcriptomics, and Mendelian randomization were integrated for analysis. The clinical data of the sequenced samples, GSE176189 and GSE122340, were used to verify the results.
Results: The level of inflammation in the severe fibrosis group was significantly higher than that in the mild fibrosis group (adjusted P < 0.0001). The results of MR showed that CCL2 had a causal relationship with BA and was a risk factor (odds ratio = 1.70, 95% confidence interval: 1.19 - 2.43, P = 0.004). The results of scRNA-seq and ST showed that the expression level of CCL2 in BA was significantly higher than that in NC (P < 0.001), and its expression level increased with the progression of fibrosis, mainly expressed in fibrotic areas. CCL2 was highly expressed in the three monocyte-macrophage subtypes with the top three fibrosis scores. CCL2+ monocyte-macrophage cells showed the strongest correlation with gamma-glutamyl transferase (R = 0.88, P = 0.0072). The interactions between CCL2+ monocyte-macrophage cells and hepatocytes, hepatic stellate cells, and bile duct epithelial cells were significantly upregulated in BA (P < 0.01). These interactions were more prominent in mild than severe fibrosis (P < 0.01).
Conclusion: Severe liver fibrosis in BA is associated with a pronounced inflammatory response. CCL2 may be crucial in the occurrence and progression of liver fibrosis in BA. Targeting CCL2+ monocyte-macrophage cells by reducing their proportion or interaction with fibrotic effector cells may provide a potential treatment for liver fibrosis in BA.
Keywords: biliary atresia, liver fibrosis, inflammation, single-cell RNA sequencing, spatial transcriptomics, mendelian randomization, CCL2
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