Clinical and serological associations of interferon-α and interferon-γ in rheumatoid arthritis patients

Interferons (IFNs) are implicated in the pathogenesis of rheumatoid arthritis (RA). However, the relationship between serum levels of IFN-α and IFN-γ and the clinical manifestations of RA, particularly regarding cardiovascular comorbidity, remains poorly established. In this study, we aimed to investigate the associations between serum concentrations of IFN-α and IFN-γ and the spectrum of disease manifestations in RA, with special attention to cardiovascular involvement.

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. IFN-α and IFN-γ serum levels were measured using the Simoa (single molecule array) technique. A multivariable linear regression analysis was performed to examine the associations between the disease characteristics and IFN-α and IFN-γ.

Serum levels of IFN-α and IFN-γ were significantly correlated with each other and were also associated with circulating levels of IL-2, IL-6 and IL-8. After multivariable adjustment, higher serum IFN-α levels were positively associated with rheumatoid factor and anti-citrullinated protein antibody positivity, as well as with increased disease activity scores. In contrast, IFN-γ levels showed no significant associations with most clinical manifestations of RA. Furthermore, neither IFN-α nor IFN-γ levels were related to cardiovascular comorbidities, including lipid profiles, insulin resistance indices or carotid ultrasound findings.

Serum levels of IFN-α, but not IFN-γ, are associated with disease activity in patients with RA. However, neither IFN is correlated with the cardiovascular comorbidities commonly observed in this population.