Aging considerations of cytokines (IL-18, IL-36α, IL-37, and IL-38) associated with rheumatoid arthritis

ABSTRACT

The pro-inflammatory cytokines IL-18 and IL-36α and the anti-inflammatory cytokines IL-37 and IL-38 are proposed to have a pathophysiological role in rheumatoid arthritis (RA). However, this role has not been well investigated in relation to aging. In this study, serum IL-18, IL-36α, IL-37, and IL-38 levels were examined in 100 RA patients who were classified as young adults (<40 years) and elderly (>60 years). A similar classification was applied to 100 healthy controls. Serum IL-18, IL-36α, and IL-38 levels were significantly elevated in all RA patients compared to controls. When comparing young adult patients to elderly patients, only IL-18 showed significantly elevated levels in elderly patients. IL-18, IL-36α, and IL-38 showed excellent performance in differentiating between young adult patients and young adult controls, whereas in elderly patients, only IL-37 retained this performance. IL-18, IL-36α, and IL-38 were associated with an increased risk of RA in young adults, whereas in the elderly, only IL-37 was associated with an increased risk of RA. In conclusion, aging is an important factor proposed to influence the association pattern of IL-18, IL-36α, IL-37, and IL-38 in RA. These findings may reshape our understanding of the role of cytokines in the pathophysiology of RA.

KEYWORDS:

• Aging
• cytokines, pro-inflammatory
• anti-inflammatory
• ROC curve
• logistic regression

Acknowledgments

The authors express their gratitude to the medical staff at Baghdad and Kadhimiya Teaching Hospitals and the National Blood Transfusion Center (Baghdad) for their assistance. We extend our thanks to the people who volunteered to participate in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.