Ultrasensitive serum interleukin-8 levels show no association with disease activity or autoantibody profile but relate to cardiovascular comorbidity in systemic lupus erythematosus.

OBJECTIVES

Interleukin 8 (IL-8) is a chemokine responsible for attracting neutrophils to inflammatory foci, facilitating their migration through interactions with adhesion molecules. Although cytokines play an important role in the pathogenesis of systemic erythematosus (SLE), the clinical relevance of circulating IL-8 levels remains uncertain due to technical difficulties in its measurement in serum. Consequently, information linking serum IL-8 concentrations with specific clinical features of SLE is limited. This study aimed to explore the relationship between serum IL-8 levels and disease activity, serological, and cardiovascular features in patients with SLE.

METHODS

In this observational and cross-sectional study, a total of 235 patients with SLE were enrolled and underwent comprehensive characterisation, including assessment of autoantibody profiles, disease activity indices (SLEDAI-2K, LLDAS), damage index (SLICC-DI), and remission status (DORIS). Cardiovascular characteristics were also assessed, including lipid profiles, insulin resistance indices, and carotid ultrasound parameters such as plaque presence, intima-media thickness, and arterial stiffness. Serum IL-8 concentrations were quantified using an innovative ultrasensitive technique, the Single Molecule Array (Simoa®). Multivariable linear regression analyses were conducted to examine the associations between circulating IL-8 levels and clinical as well as cardiovascular manifestations of SLE.

RESULTS

Disease activity scores, damage indices, and autoantibody profiles did not show significant associations with IL-8 levels. Regarding cardiovascular factors, IL-8 was inversely associated with total and non-HDL cholesterol levels in the adjusted models. The Systematic Coronary Risk Evaluation 2 (SCORE2) cardiovascular risk score showed a significant positive association with IL-8.

CONCLUSIONS

In SLE, IL-8 is not associated with disease activity or autoantibody profile but may contribute mechanistically to dyslipidaemia and accelerated atherosclerosis.