Dynamic Alterations in DNA Methylation of CD4⁺ T Cells and Macrophages in a Murine Model of Tuberculous Pleural Infection Induced by BCG Vaccination

Tuberculous pleural effusion (TPE) is a prevalent form of extrapulmonary tuberculosis, and immune abnormalities play a crucial role in promoting its development. However, the dynamic changes and regulatory characteristics of immune cells during TPE progression remain incompletely understood. This study analyzed DNA methylation and transcriptome data from macrophages and CD4⁺ T cells from pleural lavage fluid of BCG-induced tuberculous pleurisy mouse models at specific time points (Days 0, 1, 7, and 14). The results revealed substantial alterations in DNA methylation patterns associated with inflammatory factors and interferon genes. Notably, macrophages exhibited the most pronounced differences in DNA methylation profiles on Day 1, while CD4⁺ T cells demonstrated gradual changes over time. The investigation further indicated that DNA methylation primarily regulated the differentiation of Th1, Th17, and Th22 cells but not Th9 cells. Additionally, single-cell RNA sequencing analysis revealed an increasing expression of C1q during infection, which was regulated by DNA methylation. Importantly, C1q⁺ and C1q^- macrophages demonstrated distinct roles in modulating immune responses during infection. This research provides valuable insights into the DNA methylation profile of immune cells during <i>Mycobacterium bovis</i> infection-induced pleurisy in a mouse model, enhancing our understanding of the upstream regulatory mechanisms underlying immune response development in TPE.