Anti-inflammatory role of microRNA let-7c in LPS treated alveolar macrophages by targeting STAT3

Objective:To explore the expression of microRNA(miRNA) let-7c and its function in chronic obstructive pulmonary disease(COPD) and alveolar macrophage cells.Methods:Real time PCR was performed to detect the expression of miRNA let-7c in the lung tissue of COPD patients and COPD model in mice.MiRNA let-7c was overexpresscd in alveolar macrophages isolated from mice and its effect was measured by the production of pro-inflammation cytokines and the protein level of signal transducer and activator of transcription 3(STAT3) as well as phosphorylation level of STAT3 after LPS stimulation.Luciferase assay was used to detect the binding of miRNA let-7c and 3'UTR of STAT3.Results:MiRNA let-7c expression was significantly lower in patients with COPD compared with control group,and the similar result was found in COPD mice and LPS stimulated alveolar macrophages.Overexpression of miRNA lct-7c in alveolar macrophages inhibited LPS-induced increasing of tumor necrosis factor alpha,interleukin-6 and interleukin-1β.Luciferase assay showed STAT3 was a targeting of miRNA lct-7c in alveolar macrophages.Conclusions:MiRNA lct-7c low expression in COPD can regulate inflammatory responses by targeting STAT3 in alveolar macrophage,which may provide a new target for COPD treatment strategies.

Effect of PPARγagonist(rosiglitazone)on the secretion of Th2 cytokine in asthma mice

Objective: To explore the effect of PPAR γ agonist(rosiglitazone) on the secretion of Th2 cytokines and the proportion of immune cell subsets in asthma mice,Methods: Ovalbumin(OVA)-sensitized mice were used to build asthma models,Those mice were divided into the normal control group,model group and rosiglitazone group,Differences of the changes in lung histopathology of mice in the three group were observed through hematoxylin and eosin(HE) strain,and the numbers of the total cells,eosinophils and neutrophils in BALF of mice in the three groups were compared,ELISA and real-time PCR were employed to detect the protein levels of interleukin(IL)-5,IL-13,IL-4 and IL-10 and m RNA level,respectively,Flow cytometry number was implied to analyze the proportion of immune cell subsets in peripheral blood of mice,Results: Compared with the mice in the control group,and mice of the model group,the infiltration of inflammatory cells in BALF increased,bronchial smooth muscle became thickened,a large amount of collagen deposited,the secretion of Th2 cytokine increased significantly,the ratio of regulatory T cells(Treg) decreased,the ratio of T17 cells rose distinctly; while in mice of the rosiglitazone group,the changes of their lung histopathology were improved obviously,the number of infiltration of inflammatory cells declined,the thickened smooth muscle relieved,the deposition of collagen decreased,the secretion of Th2 cytokine was inhibited,the ratio of Treg went up,and the increased of the ratio of T17 cells was inhibited but still not return to normal level,Conclusions: Rosiglitazone can regulate the proportion of Treg and Th17 cells and inhibit the secretion of Th2 cytokines,which inhibit the airway inflammatory response for asthma mice effectively.