The Role And Mechanism Of IL-37 In Cigarette Smoke-induced Lung Inflammation In Mice

ObjectiveInterleukin(IL)-37 is the seventh member of the IL-1 family and has five subtypes(a-e).The current research focuses on IL-37 b,which plays an important anti-inflammatory role in a variety of inflammatory diseases.Cigarette smoke is a critical environmental factor in the pathogenesis of chronic obstructive pulmonary disease(COPD).The recent studies found that the serum level of IL-37 in patients with COPD was significantly higher than that in healthy control group.It suggests that IL-37 may be involved in the pathogenesis of inflammation of COPD.Therefore,IL-37 lentivirus were prepared in the study and cigarette smoke-induced pulmonary inflammation mice model were constructed.IL-37 lentivirus were dropped into the lungs through mice noses.To investigate the role and mechanism of IL-37 in lung inflammation induced by cigarettes in mice.It will provide an experimental basis for the clinical application of IL-37.Methods1.IL-37 lentiviral plasmids and three lentivirus packaging helper plasmids were extracted and co-transfected into 293 T cells.The virus supernatant was collected several times,purified and concentrated to obtain IL-37 lentivirus.The virus titers were measured by gradient dilution and viral infection activity was measured.2.A model of cigarette smoke-induced mouse pulmonary inflammation was constructed and the the lentivirus was nasally given into mice.Twenty mice were randomly divided into four groups: blank control group,negative control group,cigarette smoke(CS)group,experimental group.Mice(except the blank control group)were placed in an inclosed chamber and exposed to six 1R5 F research cigarettes(Tobacco and Health Research Institute,University of Kentucky,Lexington,KY,USA),each exposure lasted for about 1 h and was performed 3 times a day.The exposure was continued for 10 days.After the mice were sacrificed,bronchoalveolar lavage fluid and lung tissues were collected for detection.To investigate the effect of IL-37 on cigarette smoke-induced pulmonary inflammation in mice.Results1.After co-transfected 293 T cells with IL-37 lentiviral plasmids and three lentiviral packaging helper plasmids,green fluorescent protein expression was found after 48 h.It suggests that the lentivirus with IL-37 was successfully packaged.The lentiviral titers reached 1011TU/m L to meet the follow-up experimental requirements.Lentivirus activity assay showed that IL-37 can be highly expressed in eukaryotic cells.2.We successfully constructed a cigarette smoke-induced mouse lung inflammation model.For this,we found that IL-37 can inhibit the release of inflammatory cells.The expression levels of inflammatory cytokines like MCP-1,IL-1?,TNF-?,IL-6 and IL-17 in the IL-37 group were significantly lower compared with CS group(P<0.05).It can also inhibit the activation of NF-?B signaling pathway to reduce pulmonary inflammation in mice.The results of HE staining and PAS staining showed that the pathological symptoms in the IL-37 group were reduced compared with the CS group.ConclusionWe successfully packaged IL-37 lentivirus and high expression in eukaryotic cells.The cigarette smoke-induced model of pulmonary inflammation in mice was successfully constructed.IL-37 lentivirus can be over-expressed in the lungs of mice.IL-37 can alleviate cigarette smoke-induced pulmonary inflammation in mice by inhibiting activation of NF-?B signaling pathway.