Interleukin-35 Enhances Regulatory T Cell Function by Potentially Suppressing Their Transdifferentiation into a T Helper 17-Like Phenotype in Kawasaki Disease

ABSTRACT

Interleukin-35 (IL-35) modulates immune cell activity in inflammation and autoimmune disorders. However, its specific effects on regulatory T cells (Tregs) in Kawasaki disease remain ambiguous. We enrolled 37 patients with Kawasaki disease and 20 healthy controls in this study. The percentages of CD4⁺CD25⁺CD127^dim/- Tregs and CD4⁺IL-17A⁺ T helper 17 (Th17) cells were determined via flow cytometry. Tregs were enriched and stimulated by recombinant IL-35. Immunosuppressive activity of Tregs was via co-culture with autologous CD4⁺CD25⁻ T cells. Purified Tregs were cultured for Th17 polarization, and the influence of IL-35 on Tregs transdifferentiation into a Th17-like phenotype was determined. The percentage of Tregs was elevated in patients with Kawasaki disease and positively correlated with C-reactive protein levels. There was no significant difference in the percentage of Th17 cells between the two groups. IL-35 stimulation increased the percentage of Tregs in both groups, but decreased the percentage of Tregs Th17 cells in affected patients. IL-35 enhanced the immunosuppressive activity of Tregs in both groups, resulting in decreased cellular proliferation and increased IL-35 subunit mRNA relative levels in co-culture system. IL-35 did not affect the immune checkpoint molecule expression in Tregs, but inhibited the transdifferentiation of Tregs into a Th17-like phenotype in affected patients, indicating by the down-regulations of C-C motif chemokine receptor-4/6 expression, retinoid-related orphan nuclear receptor γt mRNA levels, and IL-17 secretion. IL-35 contributes to the immunosuppressive function of Tregs by inhibiting the cellular proliferation and transdifferentiation of Tregs into a Th17-like phenotype, which may be a protective mechanism against Kawasaki disease.

KEYWORDS:

• Interleukin-35
• Kawasaki disease
• regulatory T cells
• T helper 17 cells

Disclosure statement

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

Data availability statement

The data that support the findings of this study are available from the corresponding author Haijian Xing, upon reasonable request.

Additional information

Funding

This work is supported by the grants from Key Research & Development Plan of Shaanxi Province [2022SF-574] and Xi’an Medical Research Program [21YXYJ007].