Role Of Interleukin-38 In Airway Inflammation And Airway Remodeling Of Neutrophilic Asthma

ObjectiveAsthma is one of the most common chronic diseases in the world.Neutrophilic asthma,as a subtype of asthma,usually presents as severe and steriod-insensitive asthma,which is diffcult to cure.Interleukin(IL)-38,the tenth member of IL-1 family known as IL-1F10,plays a key role of anti-inflammatory activity in various inflammatory diseases.IL-36 receptor antagonist(IL-36Ra)inhibits the production of Th17 cells specific cytokines and IL-36 action.IL-38 share 43%similarity with IL-36 Ra,thus may be resembled.Our study aims to explore the function and underlying mechanism of IL-38 in airway inflammation and airway remodeling of neutrophilic asthma in vivo and vitro.Methods1.Neutrophilic asthma model activated by ovalbumin(OVA)and lipopolysaccharide(LPS)was established.Recombinant pc DNA3.1-m IL-38-His-V5 plasmid was injected by hydrodynamic-based delivery method.Mice were killed to collect tissue samples.Transcription factors T-bet,GATA3,RORγt and their specific cytokines interferon(IFN)-γ,IL-4,IL-17 were measured by RT-qPCR.ELISA was used to detect the content of IFN-γ and IL-17 in lung homogenates and bronchoalveolar lavage fluids(BALF).HE staining was used to measure inflammatory cell infiltration.PAS staining was added to measure mucus in pulmonary bronchi of mice.MASSON staining was to measure the amount of collagen.Immunohistochemistry was to detect hypertropy of smooth muscle.The expression of mitogen-activated protein kinase(MAPK)signaling pathway including extracelluar regulated protein kinase(ERK)1/2,phosphate(p)-ERK,c-Jun N-terminal kinase(JNK),p-JNK,p38 and p-p38 along with nuclear factor(NF)-κB andα-SMA(smooth muscle actin)were examined by Western blot.2.We cultured human bronchial smooth muscle cell(HBSMC),adding transforming growth factor(TGF)-β1 and recombinant human IL-38.The expression of T-bet,GATA3,RORγt,IFN-γ,IL-4,IL-17 were confirmed by RT-PCR.ELISA was for detection of IFN-γ and IL-17 from culture supernatants.Transwell experiment and MTT were to check the ability of cell migration and change of cell viability.The change of ERK1/2,p-ERK1/2,JNK,p-JNK,p38,p-p38,NF-κB and α-SMA were examined by Western blot.Results1.Neutrophilic asthma was successfully established by OVA and LPS challenge.IL-38 can downregulate the expression of RORγt and IL-17,reduce neutrophilic inflammatory infiltration and recruitment in lung,attenuate hypertrophy of smooth muscle and deposition of collagen which also relief airway remodeling,inhibit α-SMA and ERK1/2 signaling pathway activation.2.IL-38 can limit cell viability and migration,decrease expression of RORγt and IL-17,also restrain activation of α-SMA and ERK1/2 signaling pathway activation.ConclusionWe focus on the role of IL-38 in neutrophilic asthma mice model,found that IL-38 can downregulate the amount of inflammatory cytokines,atteunate inflammatory infiltration through ERK1/2(MAPK)signaling pathway by decreasing IL-17 expression.Low expression of α-SMA combining with the results above proved that IL-38 plays an anti-inflammatory role in neutrophilic asthma which also attenuates airway remodeling.In vitro experiments showed that IL-38 can lead to reduction of cell viability,migration,fibrosis and secretion of inflammatory cytokines.