Study On The Role Of Interleukin-33in The Pathogenesis Of Chronic Obstructive Pulmonary Disease

Objective: Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease characterized by inflammatory cell activation and the release of inflammatory mediators. Interleukin-33(IL-33) is a new member of the IL-1family, and plays a critical role in various inflammatory and immunological pathologies, but evidence for its role in COPD is lacking. The purpose of this study was to investigate the expression of IL-33, ST2and interleukin-1receptor accessory protein (IL-1RAcP) in Chronic Obstructive Pulmonary Disease (COPD).Methods:Serum IL-33, ST2and IL-1RAcP levels of112patients with COPD and30healthy adults (controls) were measured by ELISA. Meanwhile, flow cytometry was used to investigate the source of IL-33in peripheral blood. The peripheral lung tissues were obtained from6patients with COPD and6smokers with normal lung function (controls). We used immunohistofluorescence to measure the expression of IL-33in the lung tissue. The protein levels of IL-33in airway tissue were determined by Western blot.Results:Serum contents of IL-33, ST2and IL-1RAcP were increased in patients with COPD compared with control subjects. IL-33mainly expressed in lymphocytes in peripheral blood. The percentage of IL-33positive lymphocytes in COPD group was obviously higher than that of control group. IL-33positive neutrophils ratio is very low. IL-33was detected in the nuclei of epithelial cells. Additionally, the IL-33staining intensity of COPD was obviously higher than that of the control groups. In COPD patients, The IL-33protein levels of airway tissue were elevated significantly compared with those in control group.Conclusion:Our results suggest that IL-33, ST2and IL-1Racp expression was increased in COPD. IL-33mainly expressed in lymphocytes and HBEs. Objective: Smoking is one of the important risk factor of COPD, which participate in the occurrence and progression of COPD by inducing the production of various inflammatory mediators. Whether cigarette smoke can promote expression of IL-33is not yet clear. Therefore, the present study was aimed to explore the impacts of cigarette smoke on the expression and release of IL-33in vitro and vivo.Methods: Twelve mouse were randomly divided into a normal control group and a smoking model group. Mouse smoking model was established by passive smoking for8months. The lung tissue pathology was observed with HE staining. The protein levels of IL-33and ST2in plasma were measured by ELISA. The levels of IL-33and ST2mRNA in PBMCs were determined by Real-time PCR. Western blot was used to investigate the expression of IL-33in airway tissues. The HBEs were randomly divided into four groups: control group (CM group), cigarette smoke extract (CSE) group, lipopolysaccharides (LPS) group and CSE+LPS group. The levels of IL-33protein were detected by Western blot and ELISA, respectively. Cell injury and apoptosis was detected by flow cytometry with Annexin V-FITC/PI double staining.Results:Compared with the control group, lung interval damage of mouse in the smoke group declined is more obvious. The mRNA levels of IL-33and ST2in PBMCs and the protein levels of IL-33and ST2in plasma were increased in smoke group compared with control group. The expressions of IL-33in airway tissues in smoke group were significantly elevated as well. In addition, CSE and LPS stimulated IL-33expression of HBEs in vitro, and the concentrations of IL-33in the cell culture supernatant were increased accordingly.Conclusion:The expression of IL-33significantly increased in lung and peripheral blood of mouse with passive smoking induced COPD. CSE and LPS could promote IL-33expression and release in HBEs In vitro. Objective:We are aimed to investigate whether cigarette smoke could lead to increased expression of IL-33through TLR4, and to explore the relationship of TLR4gene single nucleotide polymorphisms and the different expression of IL-33in smokers.Methods:Twenty four mouse were randomly divided into four groups, including control group, intraperitoneal injection of TAK242group, cigarette smoke exposure group(S group), intraperitoneal injection of TAK242+cigarette smoke exposure group(S+TAK242group). Western blot were used to investigate the expression of TLR4and IL-33in airway tissues. The levels of TLR4and IL-33mRNA in PBMCs were determined by real Real-time PCR. The HBEs were randomly divided into six groups: control group, TAK242group, CSE group, CSE+TAK242group, lipopolysaccharides (LPS) group and LPS+TAK242group. The levels of IL-33and TLR4mRNA and protein levels were detected by real-time PCR and Western blot, respectively. The single nucleotide polymorphisms (SNPs) of TLR4polymorphism (rs4986790, rs4986791and rs11536889) in20COPD cases and20healthy controls was performed using DNA sequencing methods.Results:In the mouse model, the protein expression levels of TLR4and IL-33in airway tissues in S group were significantly elevated compared with the control group. The mRNA levels of TLR4and IL-33in PBMCs in S group were significantly increased as well. TAK242significantly prevented IL-33expression in airway tissue and PBMCs in cigarette smoke exposure mouse. CSE could promote the mRNA and protein levels of TLR4in HBEs. The IL-33expression induced by CSE and LPS was inhibited by TAK242. Detection of gene single nucleotide polymorphisms in the TLR4gene indicated that the minor alleles of the2TLR4SNPs (rs4986790and rs4986791) were not detected in all the objects in this study. There was no significant difference in the frequency of rs11536889allele in healthy controls and COPD patients. The IL-33levels in plasma did not show significant differences between subjects with GG and CG genotype in rs11536889SNP loci.Conclusion:TLR4participates in the IL-33expression induced by cigarette smoke. TLR4gene single nucleotide polymorphisms may not be related to the different expression of IL-33in smokers.