Prevalence Of Asthma Among People Aged 45 And Older In China And The Role And Mechanism Of GSDMB In Asthma

BACKGROUND Bronchial asthma is one of the most common chronic respiratory diseases in the world.Much attention has focused on childhood and adult asthma,but the population is aging rapidly in China.Therefore,it is urgent to update and explore the prevalence and risk factors of asthma in middle-aged and elderly people in China.In addition,Genome-wide association study(GWAS)have shown that the Gasdermin B(GSDMB)gene is highly associated with asthma.GSDMB is associated with the development of asthma both in gene polymorphism and protein expression.GSDMB-overexpressing bronchial epithelial cells may be involved in airway remodeling by up-regulating Transforming growth factorβ1(TGF-β1),5-Lipoxygenase(5-LO)and Matrix metalloproteinase-9(MMP9).Recent studies have revealed the mechanism of GSDMB protein mediating pyroptosis.The purpose of this study was to describe the latest prevalence and risk factors of asthma in Chinese individuals aged 45 years and older and to explore the role and mechanism of GSDMB in bronchial asthma.METHOD 1.The data for this study came from the China Health and Retirement Longitudinal Study(CHARLS)conducted by the National School of Development of Peking University in 2018.A total of 19,816 participants aged 45 and older from 28 provinces and cities in mainland China were selected as the research objects.The prevalence of asthma in this population was analyzed.The potential risk factors were analyzed by multivariate logistic regression.2.We recruited 105 subjects from the China-Japan Friendship Hospital.The basic characteristic and plasma GSDMB of all people were collected.In addition,clinical data of asthma patients were collected and plasma Interleukin-1β(IL-1β)and IL-18 were detected.The plasma GSDMB levels were compared between the asthma group and the healthy control group.Receiver operator characteristic(ROC)curve of plasma GSDMB in the diagnosis of asthma was drawn.The correlation between plasma GSDMB and clinical features was performed by Spearman Rank Analysis.3.Ovalbumin(OVA)was used to establish the allergic inflammation model of epithelium.GSDMB gene was overexpressed by plasmid transfection,and GSDMB gene was knocked out by siRNA.Transfection efficiency and the expression of GSDMB,Nuclear factorkappaB1(NF-κB1),phosphorylationp NF-κB-p65(p-p65),Inducible Nitric Oxide Synthase(iNOS)were detected by Western blot.Hoechst 33342/PI fluorescence staining combined with IL-1β and IL-18 was used to detect pyroptosis.Cell supernatant TGF-β1 was detected by ELISA,BEAS-2B cells were pre-stained with Calcein-AM and cocultured with NK-92MI cells with different effect-target ratios(1:2,1:4,1:8,1:16),then the calcein release were detected.RESULTS 1.A total of 18395 participants were eligible for the final data analysis.The estimated prevalence of asthma among Chinese people aged≥45 years in 2018 was 2.16%.Furthermore,the minority ethnicities(OR=1.55,P=0.008),older age(60-69 years group:OR=1.85,P=0.008;≥70 years group:OR=2.63,P<0.001),an education level of middle school or below(middle-school education:OR=1.88,P=0.011;primary education:OR=2.48,P<0.001;literate:OR=2.53,P<0.001;illiterate:OR=2.78),smoking(OR=1.37,P=0.003),and North(OR=1.52,P=0.01)or Northwest China(OR=1.71,P=0.005)were associated with prevalent asthma.2.In this part,70 asthmatic patients and 35 healthy individuals were collected.Gender,age,height,and weight were all matched,the median level of plasma GSDMB in the asthma group was higher than that in the healthy control group.The area under the ROC curve of plasma GSDMB in the diagnosis of asthma was 0.659(P=0.008),the optimal cut-off value was 1334pg/ml,corresponding sensitivity,specificity were 44.30%and 82.90%,respectively.In addition,the plasma GSDMB level in asthma patients was weakly positively correlated with IL-1β(r=0.265,P=0.027).There was no correlation with IL-18,FEV1%pred,Fractional exhaled nitric oxide(FeNO),sputum Eos%,blood Eos%,Serum total Immunoglobulin E(IgE)and Asthma control test(ACT)score(P>0.05).3.0.2 mg/ml OVA could increase the expression levels of GSDMB mRNA and protein in BEAS-2B cells.Overexpression of GSDMB can up-regulate the expression levels of GSDMB,NF-κB1 and p-p65 proteins.The expression levels of GSDMB,NF-κB1 and pp65 proteins were increased after OVA intervention,while the expression levels of GSDMB,NF-κB1 and p-p65 proteins were decreased treated with OVA by knocking out the GSDMB gene.In addition,overexpression of GSDMB protein could increase the percentage of cells double-stained by Hoechst 33342/PI and the levels of IL-1β,IL-18 and TGF-β1 in the supernatant of cells.The percentage of cells double-stained with Hoechst 33342/PI and the levels of IL-1β,IL-18 and TGF-β1 were increased after OVA intervention.However,the percentage of cells double-stained with Hoechst 33342/PI decreased,and the levels of IL-1β,IL-18,and TGF-β1 were decreased treated with OVA by knocking out the GSDMB gene.Futhermore,After NK-92MI cells were co-cultured for 6 h,compared with the empty plasmid,there was no significant difference in the release of calcein in different E/T(1:2,1:4,1:8,1:16)in the overexpression GSDMB group.CONCLUSION 1.The estimated prevalence of asthma among Chinese people aged ≥45 years in 2018 was 2.16%.And the risk factors include race,age,education,smoking status,and geographic region.2.The median level of plasma GSDMB in the asthma group was higher than that in the healthy control group.In addition,plasma GSDMB levels in asthma patients were weakly positively correlated with IL-1β,but not correlated with IL-18,FEV1%pred,FeNO,sputum/blood eosinophils,serum total IgE and ACT scores.3.OVA can not only activate the NF-κB canonical pathway in BEAS-2B by up-regulating GSDMB,but also increase the pyroptosis of BEAS-2B cells and promote the secretion of TGF-β1 by up-regulating GSDMB.It is speculated that GSDMB may play an important role in pro-inflammatory and remodeling in asthma.