Serum interleukin-8 levels relate to disease activity in patients with rheumatoid arthritis

Interleukin 8 (IL-8) is a chemokine involved in the pathogenesis of rheumatoid arthritis (RA). However, the clinical significance of its circulating levels remains poorly defined, partly due to technical challenges in measuring IL-8 in serum. Consequently, data on the relationship between serum IL-8 concentrations and specific disease manifestations in RA are limited.

In this study, we aimed to investigate the associations between serum IL-8 levels and clinical, serological, and cardiovascular features in patients with RA.

Cross-sectional study.

A total of 216 RA patients were recruited. They underwent comprehensive evaluations, including disease-related characteristics and disease activity indices. Moreover, complete lipid profile, insulin resistance indices, metabolic syndrome criteria, and carotid ultrasound for carotid stiffness, intima-media thickness and carotid plaque detection were assessed. The SCORE2 -Systemic Cardiovascular Risk Estimation- was also calculated. IL-8 serum levels were measured using Simoa (Single Molecule Array) technique. A multivariable linear regression analysis was performed to examine the associations between disease characteristics and IL-8.

C-reactive protein and IL-6 were significantly associated with higher IL-8 levels after multivariable adjustment. Likewise, disease activity scores were independently and positively correlated with higher serum IL-8 concentrations after adjustment for covariates. In contrast, rheumatoid factor and anti-citrullinated protein antibodies positivity showed no association with IL-8 levels. With respect to cardiovascular features, higher SCORE2 and carotid intima media thickness values were positively related to increased IL-8 concentrations.

Serum IL-8 levels are independently and positively associated with disease activity scores in patients with RA. These findings suggest that IL-8 may have potential as a biomarker in this population but requires prospective validation and comparison with standard markers. The observed relationship between IL-8 levels and the SCORE2 risk calculator suggests a potential association between IL-8 and cardiovascular disease.