To explore the role of interleukin (IL)-9 and other T helper (Th) cell-related cytokines in the pathogenesis of acute anterior uveitis.

A cross-sectional study was conducted.Thirty-six patients (36 eyes) with acute anterior uveitis who were treated at Gansu Provincial Hospital from May 2018 to May 2019 and 40 matched healthy subjects (40 eyes) who had no eye diseases or systemic diseases in the same period were enrolled as the acute anterior uveitis group and healthy control group, respectively.The disease severity of the subjects in the acute anterior uveitis group was graded and the subjects were divided into mild, moderate and severe groups according to the grading.Serum of all subjects was collected to determine the concentration of serum IL-9, IL-17, transforming growth factor-β₁ (TGF-β₁), interferon-γ (IFN-γ), IL-4, IL-35 and IL-22 by enzyme linked immunosorbent assay (ELISA) method.Spearman rank correlation analysis was used to evaluate the relationship between IL-9 concentration and other Th cell-related cytokines.This study adhered to the Declaration of Helsinki.The study protocol was approved by an Ethics Committee of Gansu Provincial Hospital (No.2019-204). Written informed consent was obtained from each subject prior to any medical examination.

The serum levels of IL-9, IFN-γ, IL-4, TGF-β₁, IL-35 and IL-22 in the acute anterior uveitis group were significantly higher than those in the healthy control group, and the differences were statistically significant (all at P<0.05). There was no statistically significant difference in the concentration of IL-17 between the two groups (U=704.500, P=0.872). The IL-9 concentration of patients with acute anterior uveitis in the mild, moderate and severe groups was 57.24 (47.47, 65.10), 71.68 (67.55, 78.91) and 114.01 (74.78, 139.30) ng/L, respectively, and the overall difference was statistically significant (Z=8.766, P=0.012), and the IL-9 concentration of the mild group and the moderate group was significantly lower than that of the severe group (both at P<0.05). The concentration of IL-9 in the patients with acute anterior uveitis was positively correlated with the concentration of IL-17, TGF-β₁ and IL-35 (r_s=0.449, 0.517, 0.400; all at P<0.05), and no significant correlations were found between the concentration of IL-9 and the concentration of IFN-γ, IL-4 and IL-22 (r_s=0.293, 0.286, 0.316; all at P>0.05).

IL-9 plays a role in promoting the immune inflammatory response in the occurrence and development of acute anterior uveitis, and it is closely related to Th17 and Treg cell-related cytokines (TGF-β₁, IL-35).

Anterior uveitis, acute; Interleukin-9; T helper cell; Cytokines