Interleukin-27 and Interleukin-2 Cooperatively Regulate CD4⁺ T Cell Subsets and Immune Imbalance in Coronary Artery Disease.

BACKGROUND: Coronary artery disease (CAD) is an immune-mediated disorder driven by dysregulated T cell responses. Interleukin-27 (IL-27) has immunoregulatory properties, but its role in CAD remains unclear. This study is the first to investigate the effects of IL-27 on CD4⁺LAP⁺ T cells in CAD and to explore its interaction with interleukin-2 (IL-2) in modulating immune imbalance. METHODS: CAD severity was quantified by the Gensini score. Plasma IL-27 and oxidized low-density lipoprotein (ox-LDL) were measured by ELISA. Flow cytometry assessed CD4⁺ T cell subsets, while qRT-PCR and Western blot evaluated lineage-specific transcription factors. RESULTS: IL-27 levels were elevated in acute coronary syndrome and correlated with ox-LDL and Gensini scores. Patients with severe CAD showed a Th1/Th17-dominant profile and reductions in Th2, CD4⁺LAP⁺, and Tregs. In vitro, IL-27 promoted Th1 differentiation via T-bet/IFN-γ upregulation and suppressed Th2, Th17, and regulatory subsets, counteracting IL-2-induced expansion of Tregs and CD4⁺LAP⁺ cells. These effects were dose dependent and favored pro-inflammatory responses. CONCLUSION: IL-27 drives immune imbalance in CAD by reinforcing Th1 polarization and antagonizing IL-2-mediated regulation. Beyond mechanistic insights, these findings identify IL-27 as a potential biomarker for disease severity and a candidate therapeutic target in CAD.