[Dynamic changes in percentages of CD4⁺ CD25⁺ regulatory T cells and Th17 cells in process of airway remodeling in mouse model of asthma].

Objective: To study the dynamic changes in Th17 cells and CD4⁺ CD25⁺ regulatory T cells (Treg) in the spleen and to analyze their relationship with airway remodeling.

Methods: A total of 48 female specific pathogen-free Balb/c mice were randomly divided into control and asthmatic groups. To establish the asthmatic airway remodeling model, the mice were sensitized to ovalbumin (OVA) through intraperitoneal injection of OVA and aluminum hydroxide suspension and challenged by inhalation of aerosol OVA. The matched control group was treated with normal saline instead. In 24 hours after 2-week, 4-week, and 8-week aerosol inhalation, 8 mice were randomly selected from each group and sacrificed. Then histopathological examination of the left lung was performed to measure the degree of airway remodeling. The percentages of Th17 and CD4⁺ CD25⁺ Treg cells in total CD4(+) cells from the spleen were determined by flow cytometry.

Results: In the asthmatic group, the ratios of total bronchial wall area to bronchial basement membrane perimeter (WAt/Pbm) and bronchial smooth muscle area to bronchial basement membrane perimeter (WAm/Pbm) significantly increased as the challenge proceeds (P<0.01). The percentage of Th17 cells derived from the cell suspension of the spleen gradually increased and it was positively correlated with the degree of asthmatic airway remodeling (P<0.01). The percentage of CD4⁺ CD25⁺ Treg cells from the suspension gradually decreased and it was negatively correlated with the degree of asthmatic airway remodeling (P<0.01).

Conclusions: In mice with asthma, as the challenge proceeds, the airway remodeling becomes more severe, the percentage of Th17 cells increases, and the percentage of CD4⁺ CD25⁺ Treg cells decreases. The immunological imbalance is possibly one of the important factors inducing airway remodeling.