Tenofovir alters the immune microenvironment of pregnant women with hepatitis B virus infection: Evidence from single-cell RNA sequencing

Background: Mother-to-child is the main route of the transmission of hepatitis B virus (HBV) infection. Tenofovir fumarate (TDF) antiviral treatment has become the most extensive choice worldwide. However, the effects of TDF treatment on the immune function of pregnant women remains unclear. Here we investigate the effect of TDF treatment on the immune microenvironment of pregnant women with HBV infection using single-cell RNA sequencing (scRNA-seq). Methods: Three HBV-infected pregnant women were treated with TDF and six samples were collected before and after the treatment. In total, 68,200 peripheral blood mononuclear cells (PBMCs) were extracted for 10 x scRNAseq. The cells were clustered using t-distributed stochastic neighbor embedding (t-SNE) and unbiased computational informatics analysis. Results: The analysis identified four-cell subtypes, including T cells, monocytes, natural killer (NK) cells, and B cells, and unraveled the developmental trajectory and maturation of CD4+ T and CD8+ T cell subtypes. The cellular state and molecular features of the effector/memory T cells revealed a significant increase in the inflammatory state of CD4+ T cells and the cytotoxic characteristics of CD8+ T cells. Additionally, after TDF treatment, the monocytes showed a tendency for M1 polarization, and the cytotoxicity of NK cells was enhanced. Furthermore, the analysis of intercellular communication revealed the interaction of various subtypes of cells and the heterogeneous expression of key signal pathways. Conclusions: The findings of this study reveal significant differences in cellular subtypes and molecular characteristics of PBMCs of pregnant women with HBV infection before and after TDF treatment and demonstrate the recovery of immune response after treatment. These findings could help develop immune intervention measures to control HBV during pregnancy and the puerperium period.