ObjectiveThis study aims to provide new targets for blocking the inflammatory injury of bronchial asthma combined with ulcerative colitis by analyzing the expression characteristics of Tfh cells and STAT3 in patients with bronchial asthma combined with ulcerative colitis. MethodsPatients with bronchial asthma, ulcerative colitis, bronchial asthma combined with ulcerative colitis, and healthy individuals were included in the study. The levels of IL-4, IL-17A, IL-10, IL-21, and IFN-γ in the serum of the participants were detected by ELISA. The proportions of Tfh cells and Tfh1, Tfh2, Tfh17, and Tfr cells in the serum were analyzed by flow cytometry. The expression levels of CXCR5, Bcl-6, Blimp-1, STAT3, and pSTAT3 in different groups were analyzed by PCR. ResultsA total of 36 subjects were included in this study. The ACT score of the bronchial asthma combined with ulcerative colitis group was lower than that of the bronchial asthma group, and the lung function was worse. The Mayo score of the bronchial asthma combined with ulcerative colitis group was higher than that of the ulcerative colitis group. Compared with the other three groups, the proportion of Tfh17 cells in the bronchial asthma combined with ulcerative colitis group was higher, and the expression of IL-4, IL-17A, IL-21and IFN-γ was higher, while the expression of IL-10 was lower. The expression of CXCR5, Bcl-6, and pSTAT3 was higher, and the expression of Blimp-1 was lower. The differences in the above results were statistically significant (P<0.05).ConclusionCompared with patients with simple bronchial asthma and simple ulcerative colitis, patients with bronchial asthma combined with ulcerative colitis present a more severe inflammatory response, which may be related to the increased proportion of STAT3 molecules and Tfh cells.