Analysis on soluble MPO, IL-8 levels and lung function characteristics in neutrophil asthma

Objective: To observe the characteristics of induced sputum, peripheral blood neutrophil (NEU) myeloperoxidase (MPO), interleukin 8 (IL-8) levels, lung function and their changes after standardized treatment in patients with neutrophil asthma(NA).Methods: 47 patients with chronic persistent asthma admitted to our hospital from January 2018 to December 2022 without standard treatment were selected and divided into NA group(n=18) and non-NA(NNA) group (n=29).Asthma control test (ACT) and lung function test were performed before and one month after treatment, respectively, including percentage of forced expiratory volume in one second to the predicted value (FEV1%), percentage of forced vital capacity in one second to forced vital capacity (FEV1/FVC%), maximum mid expiratory flow rate (MMEF75%/25%).Enzyme-linked immunosorbent assay (ELISA)was used to detect the levels of MPO and IL-8 in fasting venous blood and induced sputum and Pearson correlation analysis was used to analyze the correlation of each index.Results: Before treatment, the FEV1%、FEV1/FVC%、MMEF75%/25% in NA group were lower than those in NNA group (P＜0.05), there was no significant difference in ACT score (P＞ 0.05), and the above indexes in both groups were higher after treatment (P＜0.05).The levels of MPO, IL-8 and the percentage of NEU(NE%) in induced sputum in NA group were significantly higher than those in NNA group before and after treatment (P＜0.05), the levels of IL-8 and NE% in induced sputum in NA group decreased After treatment (P＜0.05), while MPO remained unchanged (P＞ 0.05).Before treatment, the level of IL-8 in peripheral blood of NA group was higher than that of NNA group(P＜0.05), peripheral blood IL-8 levels decreased significantly after treatment (P＜0.05), while MPO and NE%remained unchanged (P＞ 0.05).Sputum NE% was positively correlated with FEV1% and MMEF75%/25% before treatment, and peripheral blood MPO level was positively correlated with IL-8, and negatively correlated with ACT score (all P＜0.05).After treatment, peripheral blood MPO level was positively correlated with IL-8(P＜0.05).Conclusion: Sputum and peripheral blood MPO and IL-8 levels in NA patients are higher than those in NNA patients, and lung function is worse; MPO and IL-8 levels correlate with NA lung function and asthma control levels, and monitoring MPO and IL-8 levels can guide NA treatment.