Aerosol inhalation of Mycobacterium vaccae ameliorates airway structural remodeling in chronic asthma mouse model.

Background: Airway remodeling is accepted to be a determining component within the natural history of asthma. Nebulized inhalation of Mycobacterium vaccae (M. vaccae) has a protective effect on asthmatic mice. However, little is known regarding the effect of M. vaccae on airway structural remodeling in asthmatic mice. The purpose of this study was to explore the effect and the underlying mechanism of M. vaccae aerosol inhalation on airway structural remodeling in an asthma mouse model. Methods: Chronic asthma mouse models were established by ovalbumin induction. The number of inflammatory cells in bronchoalveolar lavage fluid (BALF), pathological alterations in lung tissue, and levels of associated cytokines (IL-5, IL-13, TNF-α, and ovalbumin-specific immunoglobulin E [OVA-sIgE]) were all assessed after M. vaccae therapy. The relative expression of interleukin (IL)-1ß, tumor necrosis factor-alpha (TNF-α), nuclear factor kappa B (NF-κB), and Wnt1-induced signaling protein 1 (WISP1) mRNA were detected. Western blotting and immunohistochemistry detected the expression of Wnt/ß-catenin pathway-related proteins in lung tissue. Results: M. vaccae aerosol inhalation relieved airway inflammation, airway hyper-responsiveness, and airway remodeling. M. vaccae reduced the levels of IL-5, IL-13, TNF-α, and OVA-sIgE in and downregulated the expression of IL-1ß, TNF-α, NF-κB, and WISP1 mRNA in the pulmonary. In addition, M. vaccae inhibited the expression of ß-catenin, WISP1, and Wnt1 protein and upregulated the expression of glycogen synthase kinase-3beta (GSK-3ß). Conclusion: Nebulized inhalation of M. vaccae can reduce airway remodeling during asthma.

Transcriptomic Analysis Reveals a Link Between Hippo Signaling Pathway and Macrophages in Lungs of Mice with OVA-Induced Allergic Asthma.

PURPOSE: The Hippo signaling pathway participates in the restriction of cell proliferation and organ growth. Activated macrophages have been implicated in the pathogenesis of allergic asthma. Recent studies have shown that Hippo signaling pathway may also be involved in the regulation of asthma. However, the link between Hippo signaling pathway and macrophages in the context of allergic asthma has not been investigated. The purpose of this study was to explore the link between Hippo signaling pathway and macrophages using a mice model of OVA-induced allergic asthma. METHODS: Mice models of asthma were established. Lung tissues were collected from mice and pooled for mRNA sequencing and bioinformatics analysis. The relative mRNA expression of Hippo signalling pathway-related proteins Yap1, Lef1 and Ctgf was also measured. Double immunofluorescence staining was performed on lung tissues to evaluate macrophage marker F4/80 expression and Yap1/Lef1/Ctgf expression. RESULTS: Results of the RNA-Seq of lung tissues demonstrated that the Hippo signaling pathway was down-regulated in OVA-induced allergic asthma. Using the cytoHubba tool kits in Cytoscape, the following top 10 hub genes of Hippo signalling pathway were identified: Yap1, Lef1, Ctgf, Ccnd1, Axin2, Smad7, Wnt4, Wnt3a, Pard6b, and Wwc1. Using the seq-ImmuCC (http://218.4.234.74:3200/immune/), a negative correlation was found between macrophages and Hippo signaling pathway activity (R2 = 0.93). The mRNA expression levels of pulmonary Yap1, Lef1, and Ctgf were down-regulated in the mice model of OVA-induced allergic asthma. Moreover, double-stained immunofluorescence for F4/80 and Yap1, Lef1, Ctgf in mouse lung sections respectively revealed that macrophage proliferation was correlated with downregulation of the Hippo signaling pathway in the mice model of OVA-induced allergic asthma. CONCLUSION: These results demonstrated that the Hippo signaling pathway was down-regulated in asthma mice, and the proliferation of macrophages was associated with downregulation of the Hippo signaling pathway. These findings reveal novel insights into the pathogenesis and treatment of asthma.

Effects of Mycobacterium vaccae Aerosol Inhalation on Airway Inflammation in Asthma Mouse Model.

Background:Mycobacterium vaccae vaccine, a composition of Mycobacterium proteins, has been known to have bidirectional immunomodulatory functions. Recent studies have shown that M. vaccae has a therapeutic potential for treating asthma. However, little is known regarding the effect of M. vaccae aerosol inhalation during allergen sensitization or challenge on asthma. The purpose of this study was to explore the effect and the underlying mechanism of M. vaccae aerosol inhalation during allergen sensitization or challenge on airway inflammation in an asthma mouse model. Methods: Asthma mouse models were established. Mice received aerosol inhalation with M. vaccae once daily during allergen sensitization or challenge for 5 days successively. Airway responsiveness, bronchoalveolar lavage fluid (BALF) cell count, histology, and cytokine concentrations (IL-4, IFN-γ, IL-10, and IL-17) were measured. The relative mRNA expression of ASC, caspase-1, TNF-α, and IL-1ß was also determined. Expression of pulmonary NLRP3 and nuclear factor kappa B (NF-κB) protein was measured using immunohistochemistry and Western blot. Results:M. vaccae aerosol inhalation suppressed airway hyperresponsiveness and inflammation, reduced levels of IL-4, upregulated expression of IFN-γ and IL-10 in BALF, inhibited mRNA expression of pulmonary ASC, caspase-1, TNF-α, and IL-1ß, and also inhibited expression of pulmonary NLRP3 and NF-κB protein during allergen sensitization or challenge. Conclusion:M. vaccae aerosol inhalation can suppress airway hyperresponsiveness and inflammation during allergen sensitization or challenge, and may be a promising approach for asthma therapy.