Tacrolimus and mycophenolate regimen and subclinical tubulo‐interstitial inflammation in low immunological risk renal transplants

The aim was to evaluate the relationship between maintenance immunosuppression, subclinical tubulo‐interstitial inflammation and interstitial fibrosis/tubular atrophy (IF/TA) in surveillance biopsies performed in low immunological risk renal transplants at two transplant centers. The Barcelona cohort consisted of 109 early and 66 late biopsies in patients receiving high tacrolimus (TAC‐C₀ target at 1‐year 6–10 ng/ml) and reduced MMF dose (500 mg bid at 1‐year). The Oslo cohort consisted of 262 early and 237 late biopsies performed in patients treated with low TAC‐C₀ (target 3–7 ng/ml) and standard MMF dose (750 mg bid). Subclinical inflammation, adjusted for confounders, was associated with low TAC‐C₀ in the early (OR: 0.75, 95% CI: 0.61–0.92; P = 0.006) and late biopsies (OR: 0.69, 95% CI: 0.50–0.95; P = 0.023) from Barcelona. In the Oslo cohort, it was associated with low MMF in early biopsies (OR: 0.90, 95% CI: 0.83–0.98; P = 0.0101) and with low TAC‐C₀ in late biopsies (OR: 0.77, 95% CI: 0.61–0.97; P = 0.0286). MMF dose was significantly reduced in Oslo between early and late biopsies. IF/TA was not associated with TAC‐C₀ or MMF dose in the multivariate analysis. Our data suggest that in TAC‐ and MMF‐based regimens, TAC‐C₀ levels are associated with subclinical inflammation in patients receiving reduced MMF dose.