Serum BAFF strongly correlates with PsA activity in male patients only--is there a role for sex hormones?

OBJECTIVES To determine the relationship between serum levels of B cell activating factor belonging to the TNF family (BAFF) and disease activity (DAS28) in psoriatic arthritis (PsA) patients. METHODS Twenty-two male and 31 female psoriasis patients fulfilling the CASPAR criteria for PsA were recruited for the study. Disease activity was recorded using the disease activity score for 28 joints (DAS28). Whole blood and serum samples were analysed for serum BAFF, estradiol, and testosterone levels. RESULTS Serum BAFF levels were positively correlated with DAS28 only in male PsA patients (r=0.669, p<0.001). In male but not female patients, serum testosterone was negatively correlated with DAS28 (r=-0.632, p=0.002), and serum BAFF (r=-0.520, p=0.018), respectively. The serum BAFF/ serum testosterone (B/T) ratio showed a strong correlation with DAS28 in male patients (r=0.743, p<0.0001) and, again, no correlation was found in female participants (r=0.019, p=0.93). A linear regression analysis showed that the B/T is a good predictor of DAS28 (r2=0.586, p<0.001). On the other hand, estradiol levels did neither correlate with PsA activity in male nor female patients in our study population. CONCLUSIONS Even though a role for B cells in the pathogenesis of PsA has not been established, BAFF levels correlate with disease activity in male PsA patients. Furthermore, serum testosterone in male patients negatively correlates with disease activity and BAFF, respectively. The serum BAFF/serum testosterone ratio might be used as predictor of disease activity in male PsA patients.