Inhalation of inactivated‑Mycobacterium phlei prevents asthma‑mediated airway hyperresponsiveness and airway eosinophilia in mice by reducing IL‑5 and IL‑13 levels

Evaluation of the cross-immunity between Mycobacterium tuberculosis and Mycobacterium abscessus in vitro

Mycobacterium tuberculosis (M. tuberculosis) and Mycobacterium abscessus (M. abscessus) are important pathogens that can cause lung diseases. Given the abundance of shared antigens between these two pathogens, evaluating the cross-immunization between Mycobacterium tuberculosis and Mycobacterium abscessus has implications for the assessment of tuberculosis vaccines based on nontuberculous mycobacteria (NTM). The whole-cell proteins of Mycobacterium abscessus were lysed via ultrasonication and then were subcutaneously injected into BALB/c mice either alone or mixed with adjuvant for three times at a 10-day interval. After the final immunization, cross-immune antigens were analysed via genomic comparison and Mycobacterium tuberculosis proteome microarrays. BALB/c mice splenic lymphocytes were stimulated with TB-PPD to assess the cross-immunity of the cellular immune response. The effect of cross-immunity on the growth of Mycobacterium tuberculosis was evaluated using a Mycobacterium tuberculosis growth inhibition assay. Despite the presence of 1,953 homologous gene clusters between Mycobacterium tuberculosis and Mycobacterium abscessus, only 302 Mycobacterium tuberculosis antigens exhibited cross-immunoreactivity after three immunizations. Compared with the PBS group, TB-PPD stimulation significantly increased the secretion of TNF-α, IL-4, and IL-6 by sensitized mouse splenic lymphocytes, and significantly affected the proliferation of IL-2+CD4 T and TNF-α+CD4 T cells in the immunized group (P < 0.05), but had no impact on IFN-γ and IFN-γ+ CD4 T cells. Furthermore, there was no significant difference in the proliferation of Mycobacterium tuberculosis between the immunized group and the PBS group in spleen cells. These data indicate that proteins from Mycobacterium abscessus are highly immunogenic in mice. However, the cross-immune response between Mycobacterium abscessus and Mycobacterium tuberculosis was inadequate to effectively inhibit the proliferation of Mycobacterium tuberculosis.

Aerosol Inhalation of Heat-Killed Clostridium butyricum CGMCC0313-1 Alleviates Allergic Airway Inflammation in Mice

Epidemiological studies have shown that exposure to beneficial microorganisms can reduce the risk of asthma, but the clinical use of live probiotics is controversial due to the risk of infection. As heat-killed probiotics can also exhibit immunomodulatory activity, this study is aimed at investigating whether heat-killed Clostridium butyricum (HKCB) CGMCC0313-1 could reduce allergic airway inflammation in an ovalbumin-induced mouse model. Mice received aerosol inhalation of HKCB, oral administration of HKCB, or oral administration of live Clostridium butyricum (CB) during sensitization. Bronchoalveolar lavage fluid cell number, histology, and levels of the cytokines interferon-gamma and IL-4, the autophagy-related proteins LC3B, Beclin1, and p62, and members of the nuclear factor kappa B (NF-κB)/NLRP3 inflammasome signaling pathway were examined. Our results demonstrated that aerosol inhalation of HKCB, oral HKCB administration, and oral live CB administration alleviated allergic airway inflammation and mucus secretion in allergic mice. Aerosol inhalation of HKCB was the most effective method; it restored the Th1/Th2 balance, ameliorated autophagy, and inhibited the NF-κB/NLRP3 inflammasome signaling pathway in the lungs of allergic mice. Thus, aerosol inhalation of HKCB could be a promising strategy for the prevention or treatment of asthma.

γδT17/γδTreg cell subsets: a new paradigm for asthma treatment

Bronchial asthma (abbreviated as asthma), is a heterogeneous disease characterized by chronic airway inflammation and airway hyperresponsiveness. The main characteristics of asthma include variable reversible airflow limitation and airway remodeling. The pathogenesis of asthma is still unclear. Th1/Th2 imbalance, Th1 deficiency and Th2 hyperfunction are classic pathophysiological mechanisms of asthma. Some studies have shown that the imbalance of the Th1/Th2 cellular immune model and Th17/Treg imbalance play a key role in the occurrence and development of asthma; however, these imbalances do not fully explain the disease. In recent years, studies have shown that γδT and γδT17 cells are involved in the pathogenesis of asthma. γδTreg has a potential immunosuppressive function, but its regulatory mechanisms have not been fully elucidated. In this paper, we reviewed the role of γδT17/γδTreg cells in bronchial asthma, including the mechanisms of their development and activation. Here we propose that γδT17/Treg cell subsets contribute to the occurrence and development of asthma, constituting a novel potential target for asthma treatment.

Imbalance of γδT17/γδTreg cells in the pathogenesis of allergic asthma induced by ovalbumin

We aimed to explore the imbalance between the T helper 17 γδT cells (γδT17) and the regulatory γδT cells (γδTreg) in asthmatic mice. Male Balb/c mice were randomly divided into the normal control group and the asthmatic model group. The asthmatic model group mice were intraperitoneally injected with the mixture of ovalbumin (OVA)/Al(OH)3 and then activated by exposure of the animals to OVA atomization. Airway hyperresponsiveness (AHR) was determined by a non-invasive lung function machine. Hematoxylin and eosin and Alcian blue-periodic acid Schiff staining were done for histopathological analysis. Interleukin (IL)-17 and IL-35 levels in bronchoalveolar lavage fluid were detected by ELISA. The percentage of IL-17+ γδT cells and Foxp3+ γδT cells in spleen cells suspension were detected and the transcription levels of RORγt and Foxp3 in the lung tissue were determined. Compared with the normal control, the severity of airway inflammation and AHR were higher in the asthmatic mice. Furthermore, mice in the asthmatic group displayed significant increases of IL-17+ γδT cells, expression of IL-17A, and RORγt, whereas control mice displayed marked decreases of Foxp3+ γδT cells, expression of IL-35, and transcription factor Foxp3. In addition, the mRNA expression of RORγt was positively correlated with the percentage of IL-17+γδT cells, and the mRNA level of Foxp3 was positively correlated with the percentage of Foxp3+ γδT cells. The imbalance of γδT17/γδTreg in the asthmatic mice may contribute to the pathogenesis of OVA-induced asthma.

The effect of inhaled inactived Mycobacterium phlei as a treatment for asthma

Allergic asthma is a chronic airway disorder characterized by airway inflammation, mucus hypersecretion, and airway hyperresponsiveness (AHR). A murine model of asthma was used to examine the antiasthmatic effect of inhaled inactived Mycobacterium phlei (M. phlei). AHR, neutrophil levels, eosinophil levels and levels of interleukin (IL)-17 and IL-23 receptor (IL-23R) were monitored. The results demonstrated that inactivated M. phlei alleviates the IL-17+γδT cell-mediated immune response and attenuates airway inflammation and airway hyperresponsiveness in the asthmatic murine lung, partially through inhibiting the expression of IL-23R. In conclusion, inactivated M. phlei may be an effective antiasthmatic treatment, regulating IL-17-producing γδT (IL-17+γδT) cell-mediated airway inflammation and airway hyperresponsiveness to relieve the symptoms of mice with asthma.