Pre-Transplant Cytokine Levels as Signatures of Microvascular Inflammation in Kidney Allograft Biopsies.

BACKGROUND:  The presence of microvascular inflammation (MVI) characterized by leukocyte margination in the glomeruli (glomerulitis, Banff score 'g') and peritubular capillaries (peritubular capillaritis, Banff score 'ptc') is a hallmark histological feature of antibody-mediated rejection (AMR), even in the absence of circumferential C4d positivity. In this study, we assessed the efficacy of pre-transplant plasma cytokines as an ancillary screening tool to identify MVI in kidney allograft indication biopsies to facilitate better graft survival.

METHOD:  This single-center prospective analytical study comprises 38 kidney transplant recipients whose peripheral blood was collected before transplant and assessed for the plasma cytokine concentrations of FOXP3, IL-6, TGF beta, and IL-17 using enzyme-linked immunosorbent assays (ELISA). Histopathological assessment was done in post-transplant indication biopsies, and Banff scores of 'g+ ptc' were calculated to categorize recipients into three MVI groups. The correlational, regression, and ROC curve analyses were used to assess the association and predictive ability of the cytokines with respect to MVI.

RESULTS:  In our study cohort, 27 recipients had MVI=0, five had MVI=1, and six had MVI≥2. A significant difference in plasma cytokines was observed between these groups, and we found a strong negative correlation of FOXP3 with MVI, whereas a strong positive correlation of IL-6, TGF beta, and IL-17 was recorded with MVI. We have also assessed the predictive ability of these cytokines, FOXP3, IL-6, TGF-beta, and IL-17, through the ROC curve, which showed an AUC of 0.70, 0.76, 0.84, and 0.72, respectively.

CONCLUSION:  Our findings suggest that the pre-transplant levels of cytokines FOXP3, IL-6, TGF-beta, and IL-17 could be measured to identify recipients at risk of post-transplant MVI, which could further serve as an additional tool for effective management of the kidney allograft.