Bacterial Lysates ( OM Pharma)

Broncho-Vaxom (BV) is known to attenuate allergic airway inflammation and chronic bronchitis in humans, but the underlying mechanism of this gut-mediated immunity remains unclear. This study investigated the effects of an oral BV on gut and systemic short-chain fatty acids (SCFAs) and immune responses.

Oral BV was administered daily for 15 days prior to commencing the study in an asthma mouse model. Asthma was induced by ovalbumin (OVA) sensitization followed by a challenge with 1% OVA by inhalation. Asthmatic phenotypes, gut- and systemic- immune responses, and SCFAs in the cecum and blood were then investigated.

Airway hyperresponsiveness, total immunoglobulin E production, and pulmonary inflammation were all significantly suppressed by BV. The interleukin-13 level was also suppressed, whereas TGF-β expression was increased, in the lungs of the BV-treated mice. The regulatory T (Treg) cell numbers were increased in the small intestine, and the acetate level was increased in the cecum and serum after BV treatment. The levels of acetate in the cecum and serum were negatively correlated with airway hyperresponsiveness and with the eosinophil numbers in the BAL fluid of the OVA-induced mice. There was a positive correlation between the acetate levels in the feces and serum and the lung expression of TGF-β in the asthma mice.

Oral BV administration appears to prevent allergic inflammation by enhancing Treg cell proliferation and acetate production in an asthmatic mouse model.

It has been proposed that bacterial lysates may serve as a suitable immunomodulatory oral medication to improve and control asthma symptoms. However, the difference in its efficacy in adults and children remains unclear.

Randomized controlled trials (RCTs) evaluating OM-85 add-on therapy in asthma patients up to December 2021 were searched using PubMed, Scopus, Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang database, and WP (WeiPu) database. Risk of bias was evaluated using the Cochrane risk of bias assessment tool.

A total of 36 studies were included. The results showed that OM-85 add-on treatment provided a 24% improvement in asthma symptom control [relative rates (RR) =1.24, 95% confidence intervals (CI): 1.19-1.30], and also significantly improved lung function, increased numbers of T-lymphocytes and the subtypes, and elevated levels of interferon-γ (IFN-γ), interleukin-10 (IL-10), and IL-12. Levels of serum immunoglobulin E (IgE), eosinophil cationic protein (ECP) and pro-inflammatory cytokines (including IL-4 and IL-5) were suppressed in the OM-85 add-on treatment group. Moreover, OM-85 add-on treatment showed more prominent effects in asthmatic children than in asthmatic adults.

OM-85 add-on therapy showed important clinical benefits for patients with asthma, especially asthmatic children. Further studies focusing on the immunomodulatory function of OM-85 in personalized asthma treatment are warranted.