Salivary and Serum Cytokine Concentrations in Kidney Transplantation: A Prospective Study

Kidney transplant recipients (KTRs) experience immune modulation, which may lead to graft rejection and other adverse outcomes. Although serum cytokines are well-established systemic immune markers, the role of salivary biomarkers has never been reported in the literature.

To investigate salivary and serum cytokine levels in KTRs and their correlations with clinical outcomes over time.

We evaluated the same group of 38 KTRs at T1 (< 6 months post-transplantation) and T2 (> 6 months post-transplantation). Samples were analysed with Human 6-Plex Cytokine Panel (Luminex) and clinical data were collected from medical records. Statistical analyses included Wilcoxon tests, Fisher's exact tests, Spearman's correlation, and Benjamini-Hochberg procedure for multiple comparisons (p < 0.05 significant).

Serum cytokines showed lower IFN-γ levels in cardiac events and associations of TNF-α, IL-8, and IL-10 with cytomegalovirus (CMV), BK polyomavirus (BKPyV) viremia and anaemia. Salivary cytokines showed distinct profiles, with elevated levels of TNF-α in anaemia and IL-8 in patients with diarrhoea. Those not experiencing acute rejection in both cases showed reduced salivary IL-8 levels.

Integrating serum and salivary measurements highlighted the potential of salivary biomarkers, particularly TNF-α and IL-8, in complementing traditional blood-based assays and other invasive monitoring methods in kidney transplantation.