# Clonorchis sinensis excretory/secretory proteins ameliorate inflammation in rheumatoid arthritis and ankylosing spondylitis

## TL;DR

This study shows that proteins from a parasitic worm can reduce inflammation in arthritis and spondylitis by suppressing harmful immune responses.

## Contribution

The study identifies specific proteins (Cs-GT and Cs-Severin) from Clonorchis sinensis that have anti-inflammatory effects in arthritis models.

## Key findings

- CS-ESP treatment reduced IL-17A and GM-CSF producing cells in PBMCs from RA and AS patients.
- CS-ESP significantly suppressed arthritis and enthesitis in a mouse model of AS.
- Cs-GT and Cs-Severin proteins also reduced inflammatory cytokine production without affecting cell viability.

## Abstract

We aimed to investigate whether substances secreted by Clonorchis sinensis excretory/secretory protein (CS-ESP) have an effect on the inflammation of rheumatoid arthritis (RA) and ankylosing spondylitis (AS) and to identify specific peptides through related proteomic analysis to determine which proteins exhibit anti-inflammatory effects more specifically.

Peripheral blood mononuclear cells (PBMCs) were obtained from healthy controls (HCs), RA and AS patients. Cytotoxicity of CS-ESP at different doses was assessed by MTS and flow cytometry before performing experiments. Inflammatory cytokine producing cells were analyzed using flow cytometry. To determine the effect of CS-ESP in an arthritis mouse model, 8-week-old SKG mice were injected intraperitoneally with curdlan and treated with CS-ESP; body weight and paw swelling were checked twice a week. Inflammation was evaluated using immunohistochemistry. We conducted proteomic analysis on CS-ESP and identified specific Cs-GT and Cs-Severin proteins. In vitro effect of coculture with Cs-GT and Cs-Severin was determined by inflammatory cytokine measurements.

Treatment with CS-ESP resulted in no reduced cell viability of PBMCs. In experiments culturing PBMCs, the frequencies of IL-17A and GM-CSF producing cells were significantly reduced after CS-ESP treatment. In the SKG mouse model, CS-ESP treatment significantly suppressed clinical score, arthritis and enthesitis. Treatment with Cs-GT and Cs-Severin resulted in no reduced cell viability of HC PBMCs. After Cs-GT and Cs-Severin treatment of HC PBMC, the frequencies of IL-17A and GM-CSF producing cells were significantly reduced.

We provide evidence showing that CS-ESP, Cs-GT and Cs-Severin can ameliorate clinical signs and cytokine derangements in AS.