Increased gene expression of TGF-β in peripheral blood mononuclear cells from renal transplant patients with polyomavirus BK viremia

We aimed to investigate the roles of cytokines during polyomavirus BK (BKV) reactivation in renal transplant patients. Forty-eight renal allograft recipients were enrolled, and their sera BKV viral load and mRNA expression levels of cytokines in peripheral blood mononuclear cells were measured by real-time polymerase chain reaction. Patient's age and gene expression levels of interleukin (IL)-2 (10.04 ± 2.63 vs. 8.70 ± 2.40, p = 0.049) and transforming growth factor (TGF)-β (12.58 ± 2.59 vs. 10.89 ± 1.91, p = 0.015) were significantly higher in BKV viremia (+) renal transplant patients. Multivariate logistic regression analysis revealed that age and mRNA expression levels of TGF-β, but not IL-2, significantly correlated with the presence of BKV viremia. Sera BKV viral loads showed a positive correlation with patient age and the levels of TGF-β and IL-6 mRNA. After adjusting for age and sex in the regression model, both age and TGF-β mRNA levels maintained a significant positive association with sera BKV viral loads. Serum TGF-β concentration tended to be higher in BKV viremia (+) patients (p = 0.079). In conclusion, expression levels of TGF-β were found to correlate with both BKV viremia positivity and sera BKV viral loads in renal transplant patients.