Protection against neonatal respiratory viral infection via maternal treatment during pregnancy with the benign immune training agent OM-85

Oral Bacterial Lysate OM-85: Advances in Pharmacology and Therapeutics

Background

Bacterial lysates are known for having immunomodulatory properties and have been used mainly for the prevention and treatment of respiratory tract infections (RTIs). However, rigorous studies are needed to confirm the clinical efficacy of bacterial lysates with various bacterial antigen components, preparation methods, administration routes and course of treatment. OM-85, an oral standardized lysate prepared by alkaline lysis of 21 strains from 8 species of common respiratory tract pathogens, is indicated as immunotherapy for prevention of recurrent RTIs and acute infectious exacerbations of chronic bronchitis. OM-85 acts on multiple innate and adaptive immune targets and can restore type 1 helper T (Th1)/Th2 balance. Sporadic studies have shown advances in pharmacology and therapeutics of OM-85, and thus an update review is necessary.

Methods

Literature was retrieved by searching PubMed, Web of science, Embase, CNKI, and Full Text Database of Chinese Medical Journals.

Results

New roles of OM-85 were discovered in prevention and treatment of lung cancer, pulmonary tuberculosis, SARS-CoV-2 infection, allergic rhinitis, pulmonary fibrosis, atopic dermatitis, and nephrotic syndrome. Pharmacoeconomic values of OM-85 were demonstrated in prophylaxis and treatment of RTIs, chronic obstructive pulmonary disease, asthma, chronic bronchitis, rhinosinusitis and allergic rhinitis. Two consecutive courses of OM-85 (6 or 12 months apart) could prevent recurrent RTIs in children. Maternal OM-85 treatment could offer benefits for offspring. Product-specific response was observed. The efficacy of OM-85 may be associated with patient's characteristics (eg, severity of the disease, age, immune response pattern, malignancy risk stratification).

Conclusion

OM-85 can improve effectiveness of standard care for some primary diseases, and carry significant pharmacoeconomic implications. The benefits shown by OM-85 in vitro and in vivo, when extrapolated to humans, are exciting but also require caution. Individualized treatment may need to be considered. It is necessary to compare the efficacy and safety of various bacterial lysate preparations.

Preventive effects of prenatal administration of OM-85/BV on asthma and respiratory infection risk in the offspring: A review of animal models

Asthma is the most common chronic disease in childhood affecting the daily lives of many patients despite current treatment regimens. Therefore, the need for new therapeutic approaches is evident, where a primary prevention strategy is the ultimate goal. Studies of children born to mothers in farming environments have shown a lower risk of respiratory infections and asthma development. Already at birth, these newborns have demonstrated accelerated maturation and upregulation of host defense immune functions suggesting a prenatal transplacental training of the innate immune system through maternal microbial exposure. This mechanism could possibly be utilized to help prevent both respiratory infections and asthma in young children. Human studies exploring the potential preventative effects of pregnancy bacterial lysate treatment on asthma and respiratory infections are lacking, however, this has been studied in experimental studies using mice through administrations of the bacterial lysate OM-85. This review will present the current literature on the immunomodulatory effects relevant for respiratory infections and asthma in the offspring of mice treated with OM-85 throughout pregnancy. Further, the review will discuss the cellular and molecular mechanisms behind these effects. In conclusion, we found promising results of an accelerated immune competence and improved resistance to airway challenges as a result of prenatal bacterial lysate treatment that may pave the way for implementing this in human trials to prevent asthma and respiratory infections.

From trained immunity in allergy to trained immunity-based allergen vaccines

Innate immune cells experience long lasting metabolic and epigenetic changes after an encounter with specific stimuli. This facilitates enhanced immune responses upon secondary exposition to both the same and unrelated pathogens, a process termed trained immunity. Trained immunity-based vaccines (TIbV) are vaccines able to induce innate immune memory, thus conferring heterologous protection against a broad range of pathogens. While trained immunity has been well documented in the context of infections and multiple immune-mediated diseases, the role of innate immune memory and its contribution to the initiation and maintenance of chronic allergic diseases remains poorly understood. Over the last years, different studies attempting to uncover the role of trained immunity in allergy have emerged. Exposition to environmental factors impacting allergy development such as allergens or viruses induces the reprogramming of innate immune cells to acquire a more pro-inflammatory phenotype in the context of asthma or food allergy. Several studies have convincingly demonstrated that prevention of viral infections using TIbV contributes to reduce wheezing attacks in children, which represent a high-risk factor for asthma development later in life. Innate immune cells trained with specific stimuli might also acquire anti-inflammatory features and promote tolerance, which may have important implications for chronic inflammatory diseases such as allergies. Recent findings showed that allergoid-mannan conjugates, which are next generation vaccines for allergen-specific immunotherapy (AIT), are able to reprogram monocytes into tolerogenic dendritic cells by mechanisms depending on metabolic and epigenetic rewiring. A better understanding of the underlying mechanisms of trained immunity in allergy will pave the way for the design of novel trained immunity-based allergen vaccines as potential alternative strategies for the prevention and treatment of allergic diseases.

Do bacterial vaccines/adjuvants prevent wheezing episodes in children?

PURPOSE OF REVIEW

To discuss recently discovered mechanisms of action of some bacterial vaccines that may account for their clinical benefit in the prevention of recurrent wheezing and asthma exacerbations in infants and early childhood.

RECENT FINDINGS

Trained immunity has been shown to confer innate immune cells with a quite long-term nonspecific protection against a broad spectrum of pathogens. Inducers of trained immunity include some bacterial vaccines. Trained immunity-based vaccines (TIbV) of bacterial origin have the capability to induce nonspecific responses to a variety of pathogens, including respiratory viruses, in addition to their nominal bacterial antigens. Clinical data, from epidemiological surveys to well designed randomized clinical trials, indicate that TIbV formulated with bacteria prevent respiratory tract infections of viral cause, such as those associated with recurrent wheezing or asthma exacerbation, in children. Administration of these vaccines by the mucosal route may be important for their outcome in respiratory infections.

SUMMARY

Mucosal bacterial immunotherapy, including certain TIbV, confer protection against a broad spectrum of pathogens, such as viruses, through a mechanism mediated by trained immunity. Clinical studies on the use of these preparations against recurrent wheezing reflect these mechanistic effects. These findings open a new avenue for the development of new strategies for this condition.