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

## TL;DR

This study explores saliva and blood cytokine levels in kidney transplant patients to identify potential non-invasive biomarkers for monitoring immune responses and complications.

## Contribution

The study is the first to report salivary cytokine profiles in kidney transplant recipients and their correlations with clinical outcomes.

## Key findings

- Serum cytokines like TNF-α, IL-8, and IL-10 correlated with CMV, BKPyV viremia, and anemia.
- Salivary TNF-α was elevated in anemia, and IL-8 in patients with diarrhea.
- Salivary IL-8 levels were reduced in patients without acute rejection.

## Abstract

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.