Global immune characterization of HBV/HCV-related hepatocellular carcinoma identifies macrophage and T-cell subsets associated with disease progression

Abstract

Diverse immune cells in the tumor microenvironment form a complex ecosystem, but our knowledge of their heterogeneity and dynamics within hepatocellular carcinoma (HCC) still remains limited. To assess the plasticity and phenotypes of immune cells within HBV/HCV-related HCC microenvironment at single-cell level, we performed single-cell RNA sequencing on 41,698 immune cells from seven pairs of HBV/HCV-related HCC tumors and non-tumor liver tissues. We combined bio-informatic analyses, flow cytometry, and multiplex immunohistochemistry to assess the heterogeneity of different immune cell subsets in functional characteristics, transcriptional regulation, phenotypic switching, and interactions. We identified 29 immune cell subsets of myeloid cells, NK cells, and lymphocytes with unique transcriptomic profiles in HCC. A highly complex immunological network was shaped by diverse immune cell subsets that can transit among different states and mutually interact. Notably, we identified a subset of M2 macrophage with high expression of CCL18 and transcription factor CREM that was enriched in advanced HCC patients, and potentially participated in tumor progression. We also detected a new subset of activated CD8+ T cells highly expressing XCL1 that correlated with better patient survival rates. Meanwhile, distinct transcriptomic signatures, cytotoxic phenotypes, and evolution trajectory of effector CD8+ T cells from early-stage to advanced HCC were also identified. Our study provides insight into the immune microenvironment in HBV/HCV-related HCC and highlights novel macrophage and T-cell subsets that could be further exploited in future immunotherapy.

Applications of single-cell sequencing in cancer research: progress and perspectives

“…In tumor tissues, regulatory T cells (Tregs) undergo abnormal changes in expression, such as the change in LAG3 expression observed in classic Hodgkin lymphoma, upregulated LAYN expression in FOXP3 + Helios + Tregs, and changes in CCR8 and IL1R2 expression in HCC [ 134 , 135 ]. In addition, the chronic remodeling of tumor antigens alters Treg cell frequencies and subsequently promotes the recurrence of HCC [ 136 , 137 ].…”

“…To the best of our knowledge, TAMs undergo polarized activation upon distinct exposure. Some single-cell sequencing studies demonstrated that the classically activated (M1) macrophage signature and alternatively activated (M2) macrophage signature could coexist in single macrophages, thus identifying various subsets of myeloid cells [ 136 , 149 ]. Apart from the traditional M1/M2 activation paradigm in macrophages, scRNA-seq has revealed the complexity of macrophage expression profiling.…”

“…Exhausted T cells are characterized by the high expression of inhibitory receptors, including PD-1, CTLA-4, TIM3 and LAG3, and hierarchical loss of effector functions, which is the target of ICI therapy [ 154 ]. Activated CD8 + T cells that express XCL1 at high levels are characterized as in a potential “pre-exhaustion” status and may function by recruiting cDC1 cells [ 136 ]. Moreover, the heterogeneity of CD4 + T cells might partially explain their distinct responses to tumor antigens and viral infection [ 155 ].…”

Immunopathology of Chronic Hepatitis B Infection: Role of Innate and Adaptive Immune Response in Disease Progression

“…In addition, hepatic macrophages promote HCC development by producing TNF-α and IL-6 [ 151 ]. CCL18 + M2 macrophages present in the tumors of advanced HCC promote angiogenesis, tumor invasion, metastasis, and associate with poor prognosis [ 152 ]. Hence, monocytes and macrophages play a key role in the immunopathogenesis of HBV infection.…”

Single-Cell Transcriptomic Analysis Reveals Two Molecularly and Clinically Distinct Subtypes of Intrahepatic Cholangiocarcinoma

“…5d). Indeed, we observed that, SPP1 + macrophages, which have been reported in colon cancer and closely interact with cancer-associated broblasts (CAFs) 22 , were more in ltrated in S100P-SPP1+ iCCA pps , while CCL18 + macrophages, which were abundant in advanced hepatocellular carcinoma 23 , were mostly in ltrated in S100P+SPP1-iCCA phl (Fig. 4c, d).…”