# Elevated type-17 cytokines are present in axial spondyloarthritis stool

## TL;DR

This study shows that axial spondyloarthritis patients have higher levels of Th17-related cytokines in their stool, linking intestinal inflammation to immune activity and gut metabolism.

## Contribution

The study identifies Th17 cytokines in stool and connects them to systemic immune activation and gut metabolites in axial spondyloarthritis.

## Key findings

- AxSpA patients have elevated stool IL-17A, IL-23, GM-CSF, and calprotectin.
- Circulating IL-17A+ and IL-17F+ T-helper cells are increased in AxSpA patients.
- Stool amino acids are negatively correlated with IL-23 concentrations in AxSpA.

## Abstract

Axial spondyloarthritis (axSpA) is characterized by type-17 immune-driven joint inflammation, and intestinal inflammation is present in around 70% of patients. In this study, we asked whether axSpA stool contained Th17-associated cytokines and whether this related to systemic Th17 activation. We measured stool cytokine and calprotectin levels by ELISA and found that patients with axSpA have increased stool IL-17A, IL-23, GM-CSF, and calprotectin. We further identified increased levels of circulating IL-17A+ and IL-17F+ T-helper cell lymphocytes in patients with axSpA compared to healthy donors. We finally assessed stool metabolites by unbiased nuclear magnetic resonance spectroscopy and found that multiple stool amino acids were negatively correlated with stool IL-23 concentrations. These data provide evidence of type-17 immunity in the intestinal lumen, and suggest its association with microbial metabolism in the intestine.

Graphical Abstract