Study of C-X-C chemokine receptor type 4 in systemic lupus erythematosus expression on circulating B cells as a potential biomarker for systemic lupus erythematosus activity

Background
The clinical significance of C-X-C chemokine receptor type 4 (CXCR4) dysregulation in treated and untreated systemic lupus erythematosus (SLE) patients remains unclear. This work aimed to explore the possible role of CXCR4 in the pathogenesis of SLE, comparing its level among SLE cases to healthy controls and to detect the relationship between its level and disease activity.


Patients and methods
Peripheral-blood mononuclear cells were obtained from 140 participants; 56 active (23 newly diagnosed, 33 relapsed), 14 inactive SLE patients, and 70 healthy controls. The expression of CXCR4 on cluster of differentiation19+ B cells was determined by flow cytometry.


Results
There was a highly statistically significant increase in the percentage of CXCR4-expressing B cells and mean fluorescence intensity in the SLE patients group when compared with the control group (P<0.002 and P<0.009, respectively). CXCR4-expressing B cells were more frequently observed in lupus nephritis. CXCR4 can significantly predict disease activity (area under the curve=0.797) at a cutoff greater than 1181 with high specificity with negative predictive value (84.1%), and it is highly sensitive with a high positive predictive value of 73.1%.


Conclusion
The proportion and mean fluorescent intensity of CXCR4+ circulating B cells of SLE patients significantly increase during SLE activity and lupus nephritis. This suggests that CXCR4 may serve as a clinically relevant marker for assessing SLE disease activity.