Upregulation of CX3CR1 expression in circulating T cells of systemic lupus erythematosus patients as a reflection of autoimmune status through characterization of cytotoxic capacity

Objective: This study investigated CX3CR1 expression in human peripheral blood T lymphocytes and their subsets, exploring changes in SLE patients and its diagnostic potential.

Methods: Peripheral blood samples from 31 healthy controls and 50 SLE patients were collected. RNA-Seq data from SLE patient PBMCs were used to analyze CX3CR1 expression in T cells. Flow cytometry determined CX3CR1-expressing T lymphocyte subset proportions in SLE patients and healthy controls. Subset composition and presence of GZMB, GPR56, and perforin in CX3CR1+ T lymphocytes were analyzed. T cell-clinical indicator correlations were assessed. ROC curves explored CX3CR1's diagnostic potential for SLE.

Results: CX3CR1+CD8+ T cells exhibited higher GPR56, perforin, and GZMB expression than other T cell subsets. The proportion of CX3CR1+ was higher in TEMRA and lower in Tn and TCM. PMA activation reduced CX3CR1+ T cell proportions. Both RNA-Seq and flow cytometry revealed elevated CX3CR1+ T cell proportions in SLE patients. Significantly lower perforin+ and GPR56+ proportions were observed in CX3CR1+CD8+ T cells in SLE patients. CX3CR1+ T cells correlated with clinical indicators.

Conclusion: CX3CR1+ T cells display cytotoxic features, with heightened expression in CD8+ T cells, particularly in adult SLE patients. Increased CX3CR1 expression in SLE patient T cells suggests its potential as an adjunctive diagnostic marker for SLE.