Toll-like receptor expression and clinical outcomes in incident renal transplant recipients and dialysis patients.

Aim: To assess (i) differences between Toll-like receptor (TLR2 and TLR4) expression in healthy controls and dialysis patients, and (ii) relationships between TLR expression and clinical outcomes (rejection, BK infection and renal function) in the 6-month period post-transplantation. Background(s): Increased expression of TLR has been variably associated with renal allograft rejection and function. Method(s): TLR expression on peripheral blood monocytes from 16 healthy controls and 49 dialysis patients was analysed by flow cytometry, using anti-human monoclonal antibodies and isotype control antibodies (expressed as a ratio of mean fluorescence of antibodies to isotype control antibodies). TLR measurements in 28 incident renal transplant recipients (RTR) from the dialysis cohort were obtained at 0, 3, 7 and 14 days, and 1, 2, 3 and 6 months. Linear regression models fitted to longitudinal data were used to determine associations between TLR expression and clinical outcomes. Result(s): Baseline TLR did not differ by age or 25-OH vitamin D levels; TLR2 was higher in males (2.76 vs. 2.34, p = 0.02). Baseline TLR4 (2.22 vs. 1.80, p = 0.05) but not TLR2 (2.62 vs. 2.39, p = 0.12) was higher in the dialysis group compared to controls. In RTRs, TLR4 was significantly elevated at 6 months compared to baseline (2.78 vs. 2.19, p = 0.02), however there was no significant association between baseline TLR2 and TLR4 and rejection (p = 0.70 and 0.09, respectively) or incident BK infection (p = 0.20 and 0.28, respectively). Longitudinal analysis showed no association between TLR2 and TLR4 and rejection (p = 0.21 and 0.49, respectively) or graft function (p = 0.47 and 0.53, respectively). Conclusion(s): TLR4 expression was significantly higher in dialysis patients, and TLR4 expression was significantly higher at six months in RTRs. There was no association between TLR expression and clinical outcomes.