Abstract: Objective: To investigate the relationships between the levels of serum interleukin-17(IL-17),interleukin-33(IL-33) and the concentration of fractional exhaled nitric oxide (FeNO) in the patients with chronic cough,and to further evaluate their effects in the pathogenesis of chronic cough. Methods: A total of 160 patients diagnosed with chronic cough for more than 8 weeks were chosenand used as chronic cough group.At the same time,60 healthy controlsreceived physical examination were selected as healthy control group.The levels of serum IL-17 and IL-33 of the subjects were examined and pulmonary function test,FeNO concentration test and comprehensive allergen test were performed.All data were analyzed by GraphPad Prism statistical software.The levels of serum IL-17 and IL-33 were compared between chronic cough group and healthy control groups.The correlations between the levels of serum IL-17 or IL-33 and lung function or FeNO in the patients with chronic cough were further analyzed. Results: The serum IL-17 and IL-33 levels of the patients in chronic cough groups were higher than those in healthy control group (P<0.05).The serum IL-17 and IL-33 levels in the patients with chronic cough showed a significant negative correlations with the percentage of the first second force expiratory volume to the estimated value(FEV1%) of the patients(r=-0.624 5,r=-0.672 2),and the level of serum IL-33 in the patients with chronic cough was positively correlated with the concentration of FeNO;the higher the concentration of FeNO,the higher the level of serum IL-33 (r_s=0.758,P<0.05).The FeNO concentration geometric mean of the patients with the serum total IgE<100 IU·mL^-1 (33 ppb) was significantly lower than those with the serum total IgE>200 IU·mL^-1 (78 ppb) and IgE 100-200 IU·mL^-1 (69 ppb) among the chronic cough patients (P<0.01),but there was no significant difference between the later two groups(P=0.082 4). Conclusion: The serum IL-17 and IL-33 may play an important role in the pathogenesis of chronic cough as proinflammatory factors.The levels of serum IL-17 or IL-33 have negative correlations with the pulmonary ventilation function in the patients with chronic cough.The increasing of serum IL-33 level may predict the formation of eosinophilic airway inflammation and reflect the severity of eosinophilic airway inflammation.

Key words: chronic cough, interleukin-17, fractional exhaled nitric oxide, interleukin-33, lung function