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 Distinct differences in the immune microenvironment exist between the chronic and recovery phases of brucellosis, and analysis of these differences may facilitate the identification of more appropriate indicators for treatment efficacy evaluation. CD8 Tem cells may serve as a potential biological marker for assessing the therapeutic effect of chronic brucellosis.