Th17/Treg balance, IL-6 mRNA and STAT3 mRNA levels in children with bronchial asthma combined with respiratory tract infection

OBJECTIVE To investigate the balance of helper T cell 17 (Th17) / regulatory T cell (Treg), interleukin-6 (IL-6) mRNA and activator of transcription 3 (STAT3) mRNA levels in children with bronchial asthma combined with respiratory infections, as well as the correlation between each index and infection.

METHODS Ninety-four children with bronchial asthma complicated with respiratory tract infection (infection group) and 71 children with simple bronchial asthma (non-infection group) admitted to the Qingdao Hiser Hospital Affiliated of Qingdao University from Sep. 2022 to Sep. 2023 were selected for retrospectively analysis, and 54 healthy children who underwent physical examination in the hospital during the same period were selected as the control group. The levels of Th17 cells, Treg cells, IL-6, IL-6 mRNA and STAT3 mRNA were compared among the three groups, and Pearson correlation coeffient was used to analyze the correlation of IL-6, IL-6 mRNA and STAT3 mRNA with Th17 cells and Treg cells in children with bronchial asthma complicated with respiratory tract infection.

RESULTS Respiratory pathogens in the infection group were mainly respiratory syncytial virus, accounting for 46.81%. The forced vital capacity (FVC), forced expiratory volume in one second (FEV₁) and FEV₁/FVC in the infection group were (2.31±0.36) L, (1.65±0.32) L and (0.74±0.13) L, respectively, which were low compared with those in the non-infection group and the control group, and the non-infection group was lower than the control group (P < 0.05). The levels of Th17 cells, Th17/Treg, IL-6, IL-6 mRNA and STAT3 mRNA in the infection group were (2.58±0.63) %, (0.65±0.13), (16.24±4.45) ng/L, (6.81±1.92) and (1.79±0.43), respectively, which were higher than those in the non-infection group and the control group, and those in the non-infection group was higher than those in the control group (P < 0.05). The Treg cells in the infection group was (3.95±0.89) %, lower than that in the non-infection group and the control group, and that in the non-infection group was lower than that in the control group (P < 0.05). Spearman correlation analysis showed that IL-6 mRNA and STAT3 mRNA were positively correlated with Th17 cells (r=0.575, 0.553, P < 0.001), and negatively correlated with Treg cells (r=-0.682, -0.533, P < 0.001).

CONCLUSION Respiratory tract infections significantly aggravate the imbalance of Th17/Treg in children with bronchial asthma and activate the activity of IL-6/STAT3 pathway.