Objective To explore the mechanism of Juanxiao decoction in regulating type 3 innate lymphoid cells(ILC3s)in treating obese asthma.Methods Sixty male BALB/c mice were randomly divided into a normal group,model group(high-fat diet+OVA),Juanxiao decoction groups(low,middle,and high doses of 8.5,17,and 34 g/kg,respectively),and dexamethasone group(1 mg/kg)with 10 mice in each group.Except for the normal group,the other groups were fed a high-fat diet for 12 weeks,and OVA sensitization by inhalation of an atomized OVA solution was used to establish the obese asthma model.From the first inhalation,the low-,medium-,and high-dose groups of Juanxiao decoction and the dexamethasone group were administered corresponding drugs by gavage,whereas normal and model groups were administered equal amounts of saline by gavage for 7 days.The state of mice and changes in typical symptoms of obese asthma were observed.At 24 hours after the last challenge,a fully automated biochemical analyzer was used to assess four blood lipids and count inflammatory cells in alveolar lavage fluid(BALF).Hematoxylin-eosin staining was used to observe morphological changes in lung tissue and abdominal fat.Enzyme-linked immunosorbent assays were used to measure the immunoglobulin E in BALF and serum,and interleukin(IL)-1β,IL-13,and mouse thymus activation regulating chemokine(CCL17)in lung tissue.IL-17A+ILC3 and IL-22+ILC3 in lung tissue and peripheral blood were analyzed by flow cytometry.Western blot was used to detect expression of P-STAT3 protein in lung tissue.Results Compared with the normal group,model group mice showed infiltration of airway inflammatory cells and thickening of airway walls.However,compared with the model group,lung inflammation in dexamethasone and Juanxiao decoction groups was improved,especially in middle-and high-dose groups.Compared with the normal group,IL-1β,IL-17A+ILC3,IL-13,and CCL17 in lung tissue of the model group were significantly increased(P＜0.05),whereas the proportion of IL-22+ILC3 and expression of P-STAT3 were significantly decreased(P＜0.01,P＜0.05).Compared with the model group,IL-1β,IL-17A+ILC3,IL-13,and CCL17 in lung tissue were significantly decreased and the proportion of IL-22+ILC3 and expression of P-STAT3 were significantly increased in middle-and high-dose Juanxiao decoction groups(P＜0.05,P＜0.01,P＜0.001).Conclusions Juanxiao decoction improves the inflammatory environment of obese asthmatic mice and alleviates lung inflammatory and allergic reactions.Its mechanism may be related to regulating secretion of cytokines by ILC3s.