Immunological Characteristics of Chronic Brucellosis and Preliminary Study on CD8 Tem for Efficacy Evaluation

Objective To investigate the immunological characteristics of chronic brucellosis and to identify potential indicators for treatment efficacy evaluation.Methods Transcriptomic data from the GEO database were integrated to identify differentially expressed genes between patients with chronic brucellosis and healthy controls. In addition, single-cell RNA sequencing (scRNA-seq) combined with flow cytometry was used to characterize the immune cell landscape of peripheral blood mononuclear cells from patients in the chronic and recovery phases.Results Compared with healthy controls, patients in the chronic phase showed an increased proportion of CD8+ T cells. A total of 11 immune cell subsets were identified at the single-cell level, among which CD8 Tem cells were enriched in the chronic phase but decreased in the recovery phase. Six candidate genes were further screened and showed potential value in evaluating treatment efficacy in chronic brucellosis. Flow cytometry results were consistent with the single-cell findings and confirmed that the proportion of CD8 Tem cells in recovery-phase patients was lower than that in chronic-phase patients.Conclusion Understanding immune microenvironment differences is key to finding better markers for evaluating chronic brucellosis treatment. Our study suggests CD8 Tem cells might serve as a promising biological indicator for assessing therapeutic outcomes in chronic brucellosis.