# Increased Intestinal Permeability and Articular Involvement in Systemic Lupus Erythematosus Patients—A Mutually Exclusive Relationship?

## TL;DR

This study explores the relationship between intestinal permeability and joint involvement in systemic lupus erythematosus patients.

## Contribution

The study reveals a paradoxical inverse relationship between intestinal permeability and articular involvement in SLE patients.

## Key findings

- Caucasian SLE patients had significantly higher plasma zonulin levels compared to controls.
- SLE patients with articular involvement had lower zonulin levels than those without.
- Zonulin levels did not correlate with disease activity measured by SLEDAI.

## Abstract

Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disorder characterized by complex interactions between the innate and adaptive immune systems, being potentially associated with an enhanced intestinal permeability. Zonulin represents a key protein in the modulation of intestinal permeability, being a gut leakage marker. The purpose of the present work was to evaluate the intestinal permeability, through serum zonulin levels, and to explore the relationships between zonulin, disease activity, and organ involvement in Caucasian SLE patients. The study had a cross-sectional design and included two groups of subjects: the SLE group (n = 41) and the control group (n = 29). Plasma zonulin level was measured using indirect ELISA. Despite the fact that Caucasian SLE patients exhibited higher plasma zonulin levels compared to the control group (7.566 ± 1.368 ng/mL vs. 2.306 ± 0.286 ng/mL, p < 0.01, Mann–Whitney-U-test), plasma zonulin levels did not correlate with disease activity measured by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). SLE patients with clinical articular involvement had paradoxically lower plasma zonulin levels than those without this manifestation. The results support the hypothesis of a mutually exclusive inflammatory “signature” between intestinal mucosa and synovium.