Single-cell RNA-seq Revealed that Altered Tumor Infiltrating Lymphocytes in Cirrhotic Liver Indicate Development of Hepatocellular Carcinoma

Background and Aims: Cirrhosis is the precursor lesion for most hepatocellular carcinoma (HCC) cases. However, no biomarker effectively predicted HCC initiation before diagnosis by imaging. We aimed to investigate the hallmarks of immune microenvironments in healthy, cirrhotic livers and HCC tumor tissues and to identify immune biomarkers of cirrhosis-HCC transition. Methods: Expression matrices of single-cell RNA sequencing studies were downloaded and integrated with Seurat package vignettes. Clustering was performed to analyze the immune cell compositions of different sample types. Results: The cirrhotic liver and HCC tumors had distinct immune microenvironments, but the immune landscape of cirrhotic livers was not markedly modified compared with healthy livers. Two subsets of B cells and three subsets of T cells were identified in the samples. Among the T cells, naïve T cells were more prominent in the cirrhotic and healthy liver samples than in the HCC samples. In contrast, the neutrophil count was lower in cirrhotic livers. Two macrophage clusters were identified, one that actively interacted with T cells and B cells and was enriched in cirrhotic blood compared with HCC blood samples. Conclusions: Decreased naïve T cell infiltration and increased neutrophil infiltration in the liver may indicate the development of HCC in cirrhotic patients. Alterations in blood-resident immune cells may also be a sign of HCC development in cirrhotic patients. The dynamics of the immune cell subsets may serve as novel biomarkers to predict the transition from cirrhosis to HCC.