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.

Aerosol inhalation of Mycobacterium bovis can reduce the Th2 dominant immune response induced by ovalbumin sensitization.

OBJECTIVE: To investigate whether M. vaccae inhalation affects asthma via γδ T cell regulation. METHODS: Forty male Balb/c mice were randomly divided into 4 groups: normal group, asthma group, control group and intervention group. The normal group was given no treatment. For the asthma group, control group and intervention group, the mice were sensitized and stimulated with ovalbumin (OVA) to establish asthma models. Mice in the asthma group were not treated. Mice in the control group were treated with γδ T cell suspension from normal mice, and those in the intervention group were treated with γδ T cell suspension from mice intervened by Mycobacterium bovis. ELISA assay was adopted for quantification of IL-4 and IFN-γ in mouse alveolar fluid (BALF), and flow cytometry for determining the percentage of IL-4 and IFN-γ from mononuclear cells of lung tissues. RESULTS: The airway responsiveness of the asthma group was higher than that of the normal group. The degree of airway inflammation in the intervention group was lighter than that in the control group, and it was significantly alleviated compared with the asthma group (P<0.05). Compared with the asthma group, the level of IL-4 in the BALF of the control group and the intervention group decreased significantly, while the level of IFN-γ increased significantly (P<0.05). Compared with the control group, the level of IL-4 in the BALF of the intervention group was significantly lower, while the level of IFN-γ was significantly higher (P<0.05). In addition, the results of flow cytometry were basically consistent with the results of Elisa. CONCLUSION: Aerosol inhalation of Mycobacterium bovis can alleviate the Th2 dominant immune response induced by OVA sensitization and regulate the Th1/Th2 immune imbalance in patients with asthma.

Probiotics for Preventing Upper Respiratory Tract Infections in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Upper respiratory tract infections (URTIs) are common and burdensome infectious illness. Several trials have reported that probiotics can prevent URTIs in adults. OBJECTIVES: To evaluate the efficacy and safety of probiotics in the prevention of URTIs in adults. METHODS: PubMed, Web of Science, Embase, and Cochrane Library were searched for reports published from database inception to May 14, 2020. Randomized controlled trials (RCTs) comparing probiotics with placebo for the prevention of URTIs in adults were included. RESULTS: Six RCTs with 1551 participants were included. Compared with the placebo group, the probiotics intervention group significantly reduced the incidence of URTI episodes (RR: 0.77; 95% CI: 0.68 to 0.87; P < 0.0001; I 2 = 26%), the episode rate of URTIs (rate ratio: 0.72; 95% CI: 0.60 to 0.86; P = 0.0002; I 2 = 99%), and the mean duration of one episode of URTI (MD: -2.66; 95% CI: -4.79 to -0.54; P = 0.01; I 2 = 80%). The adverse events of probiotics were mainly mild gastrointestinal symptoms. There were no significant differences in occurrence rate of adverse effects between probiotics intervention and placebo group (rate ratio: 1.01; 95% CI: 0.80 to 1.26; P = 0.96; I 2 = 99%). CONCLUSION: Low-quality evidence provides support that probiotics have potential efficacy for preventing URTI episodes in adults. More trials are required to confirm this conclusion.