Selective activation of human dendritic cells by OM-85 through a NF-kB and MAPK dependent pathway

European Respiratory Society Research Seminar on Preventing Pediatric Asthma

This report is a summary of the presentations given at the European Respiratory Society's Research Seminar on Asthma Prevention. The seminar reviewed both epidemiological and mechanistic studies and concluded that; (i) reducing exposure of pregnant women and children to air pollution will reduce incident asthma, (ii) there are promising data that both fish oil and a component of raw cow's milk prevent asthma, and (iii) modulating trained immunity by either mimicking helminth infection or oral and sublingual bacterial products is a promising area of research.

OM-85 attenuates high-fat diet-induced obesity, insulin resistance, gut dysbiosis and nonalcoholic steatohepatitis in a murine model

BACKGROUND

Obesity is a global epidemic that is tied to a wide range of human disorders. Chronic consumption of a high-fat diet is linked to disruption of the intestinal microbiome, which drives obesity-related pathophysiology. Broncho-Vaxom® (OM-85), a bacterial lysate used for prophylaxis of recurrent respiratory tract infections, has both immunostimulatory and immunomodulatory functions.

METHODS

Male C57Bl/6 mice were maintained on normal control vs. high-fat diets for 8 weeks and treated or untreated with OM-85 or with the probiotic Lactobacillus plantarum, as a positive control. Mice were evaluated for weight gain, glucose tolerance, insulin tolerance, gut microbiome composition and non-alcoholic steatohepatitis (NASH).

RESULTS

High-fat diet mice developed obesity, insulin resistance, NASH and gut dysbiosis with a shift from the Bacteroidetes phylum, such as Bacteroidales order and Muribaculaceae family organisms to Firmicutes groups, such as the Clostridium and Blautia genuses. Treatment with OM-85 led to 1) prevention of obesity, 2) prevention of insulin resistance, 3) attenuation of NASH and 4) attenuation of gut dysbiosis, with decreased levels of the organisms mentioned above and increases in Verrucomicrobiae phylum organisms such as Akkermansia family microbes as well as Muribaculaceae organisms. These shifts in the gut microbiome predict favorable effects on the short chain fatty acid profile in the gut and increased integrity of the intestinal barrier. Pathway analysis showed that OM-85 decreases rates of carbohydrate metabolism, providing an additional mechanism whereby OM-85 prevents obesity.

CONCLUSION

Immune modulators such as OM-85 should be investigated for their potential therapeutic effects on metabolism.

Is There a Role for Immunostimulant Bacterial Lysates in the Management of Respiratory Tract Infection?

Bacterial Lysates are immunostimulants clinically prescribed for the prevention of respiratory tract infections (RTIs). It has been shown that Bacterial Lysates upregulate the immune system, acting both on innate and adaptive reactions. In fact, there are demonstrations of their efficacy in restoring the integrity and immune function of epithelial barriers, activating ILC3 and dendritic cells with an enhanced Th1 response, and producing serum IgG and serum and salivary IgA specific to the administered bacterial antigens. The activated immune system also protects against other bacteria and viruses due to a trained immunity effect. Most studies show that the number of RTIs and their severity decrease in Bacterial Lysates-pretreated patients, without relevant side effects. The Bacterial Lysates treatment, in addition to reducing the number of RTIs, also prevents the deterioration of the underlying disease (i.e., COPD) induced by repeated infections. Despite these positive data, the most recent meta-analyses evidence the weakness of the studies performed, which are of low quality and have an inadequate number of patients, some of which were non-randomized while others were without a control group or were performed contemporarily in different clinical conditions or with different ages. The high heterogeneity of the studies does not allow us to state Bacterial Lysates' effectiveness in preventing RTIs with sufficient certainty. To completely define their indications, double-blind, placebo-controlled, multicenter, randomized clinical trials should be performed for each product and for each indication. The study population should be adequate for each indication. For this purpose, an adequate run-in phase will be necessary.

Advances in Bacterial Lysate Immunotherapy for Infectious Diseases and Cancer

Antigenic cell fragments, pathogen-associated molecular patterns, and other immunostimulants in bacterial lysates or extracts may induce local and systemic immune responses in specific and nonspecific paradigms. Based on current knowledge, this review aimed to determine whether bacterial lysate has comparable functions in infectious diseases and cancer treatment. In infectious diseases, including respiratory and urinary tract infections, immune system activation by bacterial lysate can identify and combat pathogens. Commercially available bacterial lysates, including OM-85, Ismigen, Lantigen B, and LW 50020, were effective in children and adults in treating respiratory tract infections, chronic obstructive pulmonary disease, rhinitis, and rhinosinusitis with varying degrees of success. Moreover, OM-89, Uromune, Urovac, Urivac, and ExPEC4V showed therapeutic benefits in controlling urinary tract infections in adults, especially women. Bacterial lysate-based therapeutics are safe, well-tolerated, and have few side effects, making them a good alternative for infectious disease management. Furthermore, a nonspecific immunomodulation by bacterial lysates may stimulate innate immunity, benefiting cancer treatment. "Coley's vaccine" has been used to treat sarcomas, carcinomas, lymphomas, melanomas, and myelomas with varying outcomes. Later, several similar bacterial lysate-based therapeutics have been developed to treat cancers, including bladder cancer, non-small cell lung cancer, and myeloma; among them, BCG for in situ bladder cancer is well-known. Proinflammatory cytokines, including IL-1, IL-6, IL-12, and TNF-α, may activate bacterial antigen-specific adaptive responses that could restore tumor antigen recognition and response by tumor-specific type 1 helper cells and cytotoxic T cells; therefore, bacterial lysates are worth investigating as a vaccination adjuvants or add-on therapies for several cancers.

The bacterial lysate OM-85 engages Toll-like receptors 2 and 4 triggering an immunomodulatory gene signature in human myeloid cells

OM-85 is a bacterial lysate used in clinical practice to reduce duration and frequency of recurrent respiratory tract infections. Whereas knowledge of its regulatory effects in vivo has substantially advanced, the mechanisms of OM-85 sensing remain inadequately addressed. Here, we show that the immune response to OM-85 in the mouse is largely mediated by myeloid immune cells through Toll-like receptor (TLR) 4 in vitro and in vivo. Instead, in human immune cells, TLR2 and TLR4 orchestrate the response to OM-85, which binds to both receptors as shown by surface plasmon resonance assay. Ribonucleic acid-sequencing analyses of human monocyte-derived dendritic cells reveal that OM-85 triggers a pro-inflammatory signature and a unique gene set, which is not induced by canonical agonists of TLR2 or TLR4 and comprises tolerogenic genes. A largely overlapping TLR2/4-dependent gene signature was observed in individual subsets of primary human airway myeloid cells, highlighting the robust effects of OM-85. Collectively, our results suggest caution should be taken when relating murine studies on bacterial lysates to humans. Furthermore, our data shed light on how a standardized bacterial lysate shapes the response through TLR2 and TLR4, which are crucial for immune response, trained immunity, and tolerance.

Neferine Attenuates HDM-Induced Allergic Inflammation by Inhibiting the Activation of Dendritic Cell

House dust mite (HDM) acts as an environmental antigen that might cause chronic allergic diseases. Neferine (NEF) shows anti-inflammation therapeutic effects. This study is to explore the protection role of NEF against HDM-induced allergic inflammation. HDM-induced allergic asthmatic C57BL/6J mice models were established. Differential histological staining was used to analyze lung tissue pathological scores. Flow cytometry was used to analyze subtypes and biomarker expression of immune cells. RT-PCR and ELISA were used to test cytokines-related gene and/or protein expression levels. Western blot was performed to investigate the signaling pathway that mediates allergic inflammation from mice lung tissue and bone marrow-derived dendritic cells (BMDCs). H&E and PAS staining results indicate NEF significantly attenuated inflammatory index and the percentage of goblet cells in the lung tissue induced by HDM. The HDM-elevated TH2 and TH17 cells were significantly decreased by NEF; inflammatory cytokines Il-4, Il-13 and Il-17 were dramatically downregulated in the NEF plus HDM group compared with HDM alone. CD40+ and CD86+ DCs, eosinophils and mast cells, and ILC2 cells were decreased by NEF which was elevated under HDM stimulation. In vivo and ex vivo investigations indicated NEF can attenuate the activated NF-κB signaling induced by HDM is involved in allergic inflammatory immune response and regulates cytokines-related gene expression. HDM-activated DCs promoted differentiation of TH2 and TH17 cells but were attenuated by NEF. This study suggests NEF interrupts the overexpression of some cytokines released by DCs, TH2, and TH17 cells; NEF attenuates HDM-induced allergic inflammation via inhibiting NF-κB signaling of DCs.

Effect of Broncho-Vaxom (OM-85) on the frequency of chronic obstructive pulmonary disease (COPD) exacerbations

BACKGROUND

Efforts have been made to reduce the risk of chronic obstructive pulmonary disease (COPD) exacerbations using a variety of measures. Broncho-Vaxom (BV) is an immunomodulating agent that has shown potential benefit by balancing between immune stimulation and regulation in patients with COPD. In this study, we evaluated the clinical efficacy of BV for reducing the risk of COPD exacerbations.

METHODS

This study was based on the Korean National Health Insurance database, which contains reimbursement information for almost the entire population of South Korea. We extracted data from 2016 to 2019 for patients started on BV during 2017-2018. We collected baseline data on demographics, comorbidities, inhaler use, hospital type, and insurance type 1 year before starting BV. We also analyzed exacerbation history, starting from the year before BV initiation.

RESULTS

In total, 238 patients were enrolled in this study. Their mean age was 69.2 ± 9.14 years, 79.8% were male, and 45% experienced at least one exacerbation. BV reduced the risk of moderate (odds ratio [OR] = 0.59, 95% confidence interval [CI]: 0.38-0.91) and moderate-to-severe exacerbations compared to pre- and post-BV (OR = 0.571, 95% CI: 0.37-0.89). BV use also reduced the incidence of moderate and moderate-to-severe exacerbations (incidence rate ratio [IRR] = 0.75, p = 0.03; and IRR = 0.77, p = 0.03, respectively). The use of BV was significantly delayed moderate exacerbations (hazard ratio = 0.68, p = 0.02), but not with moderate-to-severe or severe exacerbations.

CONCLUSION

The use of BV was associated with fewer moderate and moderate-to-severe exacerbations. Additionally, BV was associated with a delay in moderate COPD exacerbations.

Bacterial immunotherapy is highly effective in reducing recurrent upper respiratory tract infections in children: a prospective observational study

PURPOSE

Whilst immunotherapy is an appealing option as it could reduce the burden of recurrent pediatric respiratory tract infections (RTI), there is limited evidence on its effectiveness and more research was requested in order to better understand this therapeutic modality.

METHODS

We performed a prospective cohort study involving 57 subjects to assess the safety and effectiveness a 3-month regimen of either typified or patient-specific bacterial lysates could have in reducing the number of RTIs in children aged 0 to 11 years with histories of recurrent episodes.

RESULTS

After a 6-month follow-up, the number of RTIs and school absenteeism dropped sharply and significantly, from an adjusted mean (standard error) of 0.6 (0.04) episodes/month to 0.1 (0.03) episodes/month (74.7% reduction, P < 0.001), and from an adjusted mean score of 4.6 (1.06) points to 0.0 (0.01) points over 10 (99.5% reduction, P < 0.001), respectively. There was also a significant decrease in the severity of symptoms. No adverse reactions were observed.

CONCLUSION

The use of the study product is associated with a decreased risk of recurrent RTIs in children, with a very favorable safety profile that warrants further investigation in randomized clinical trials.

The Use of Bacterial Lysate for the Prevention of Wheezing Episodes in Preschool Children: A Cost-Utility Analysis

BACKGROUND

Although increasing recent evidence has shown the efficacy of bacterial lysate therapy for the prevention of wheezing episodes and asthma exacerbations in pediatric patients, evidence of its cost-effectiveness in preschool patients is scarce.

OBJECTIVES

To evaluate the cost-utility of bacterial lysate therapy as an add-on to standard care of preschool children with recurrent wheezing.

METHODS

To achieve the objectives of the study, we used a Markov simulation model with 3 mutually exclusive nonabsorbent states (regular Markov chain). Effectiveness parameters were obtained from a recent systematic review of the literature with meta-analyses (5 randomized controlled trials, 433 children). Cost data were obtained from hospital bills and from the national manual of drug prices in Colombia. The study was carried out from the perspective of the national health care system in Colombia. The main outcome of the model was quality-adjusted life-years. To assess the robustness of the model's results, we performed deterministic and probabilistic sensitivity analysis.

RESULTS

Compared with standard care, bacterial lysate add-on therapy to standard care was associated with lower overall treatment costs (US $694.03 vs $830.71 average cost per patient) and the greatest gain in QALYs (0.9211 vs 0.9154 QALYs on average per patient), thus showing dominance.

CONCLUSIONS

In Colombia, compared with standard care, bacterial lysate add-on therapy to standard care for treating preschool children with recurrent wheezing is a dominant strategy because it showed a greater gain in QALYs at lower total treatment costs.

Promising Immunomodulatory Effects of Bacterial Lysates in Allergic Diseases

In light of an escalating prevalence of allergic disorders, it is crucial to fully comprehend their pathophysiology and etiology. Such knowledge would play a pivotal role in the search for new therapeutic approaches concerning not only diseases' symptoms, but also their underlying causes. The hygiene hypothesis indicates a high correlation between limited exposure to pathogens in early childhood and the risk of developing allergic disorders. Bearing in mind the significance of respiratory and digestive systems' mucous membrane's first-line exposure to pathogens as well as its implications on the host's immune response, a therapy targeted at aforesaid membranes could guarantee promising and extensive treatment outcomes. Recent years yielded valuable information about bacterial lysates (BLs) known for having immunomodulatory properties. They consist of antigen mixtures obtained through lysis of bacteria which are the most common etiologic agents of respiratory tract infections. They interact with dendritic cells located in the mucous membranes of the upper respiratory tract and the gastrointestinal tract by toll-like receptors. The dendritic cells present acquired antigens resulting in innate immune response development on the release of chemokines, both stimulating monocytes and NK cells maturation and promoting polymorphonuclear neutrophil migration. Moreover, they influence the adaptive immune system by stimulating an increase of specific antibodies against administered bacterial antigens. The significance of BLs includes not only an anti-inflammatory effect on local infections but also restoration of Th1/Th2 balance, as demonstrated mainly in animal models. They decrease Th2-related cytokine levels (IL-4, IL-13) and increase Th1-related cytokine levels (IFN-γ). The reestablishment of the balance of the immune response leads to lowering atopic reactions incidence which, in addition to reduced risk of inflammation, provides the alleviation and improvement of clinical manifestations of allergic disorders. In this review, we hereby describe mechanisms of BLs action, considering their significant immunomodulatory role in innate immunity. The correlation between local, innate, and adaptive immune responses and their impact on the clinical course of allergic disorders are discussed as well. To conclude our review, we present up-to-date literature regarding the outcomes of BLs implemented in atopic dermatitis, allergic rhinitis, and asthma prevention and treatment, especially in children.

Can bacterial lysates be useful in prevention of viral respiratory infections in childhood? The results of experimental OM-85 studies

Respiratory tract infections (RTI) are mainly viral in origin and among the leading cause of childhood morbidity globally. Associated wheezing illness and asthma are still a clear unmet medical need. Despite the continuous progress in understanding the processes involved in their pathogenesis, preventive measures and treatments failed to demonstrate any significant disease-modifying effect. However, in the last decades it was understood that early-life exposure to microbes, may reduce the risk of infectious and allergic disorders, increasing the immune response efficacy. These results suggested that treatment with bacterial lysates (BLs) acting on gut microbiota, could promote a heterologous immunomodulation useful in the prevention of recurrent RTIs and of wheezing inception and persistence. This hypothesis has been supported by clinical and experimental studies showing the reduction of RTI frequency and severity in childhood after oral BL prophylaxis and elucidating the involved mechanisms. OM-85 is the product whose anti-viral effects have been most extensively studied in vitro, animal, and human cell studies and in translational animal infection/disease models. The results of the latter studies, describing the potential immune training-based activities of such BL, leading to the protection against respiratory viruses, will be reported. In response to human rhinovirus, influenza virus, respiratory syncytial virus and severe acute respiratory coronavirus-2, OM-85 was effective in modulating the structure and the functions of a large numbers of airways epithelial and immune cells, when administered both orally and intranasally.

OM-85 Broncho-Vaxom®, a Bacterial Lysate, Reduces SARS-CoV-2 Binding Proteins on Human Bronchial Epithelial Cells

In clinical studies, OM-85 Broncho-Vaxom®, a bacterial lysate, reduced viral respiratory tract infection. Infection of epithelial cells by SARS-CoV-2 depends on the interaction of its spike-protein (S-protein) with host cell membrane proteins. In this study, we investigated the effect of OM-85 on the expression of S-protein binding proteins by human bronchial epithelial cells. Human bronchial epithelial cells were treated with OM-85 over 5 days. The expression of SARS-CoV-2 receptor angiotensin converting enzyme 2 (ACE2), transmembrane protease serine subtype 2 (TMPRSS2), dipeptidyl peptidase-4 (DPP4), and a disintegrin and metalloprotease 17 (ADAM17) were determined by Western blotting and quantitative RT-PCR. Soluble (s)ACE2, heparan sulfate, heparanase, and hyaluronic acid were assessed by ELISA. OM-85 significantly reduced the expression of ACE2 (p < 0.001), TMPRSS2 (p < 0.001), DPP4 (p < 0.005), and cellular heparan sulfate (p < 0.01), while ADAM17 (p < 0.02) expression was significantly upregulated. Furthermore, OM-85 increased the level of sACE2 (p < 0.05), hyaluronic acid (p < 0.002), and hyaluronan synthase 1 (p < 0.01). Consequently, the infection by a SARS-CoV-2 spike protein pseudo-typed lentivirus was reduced in cells pretreated with OM-85. All effects of OM-85 were concentration- and time-dependent. The results suggest that OM-85 might reduce the binding of SARS-CoV-2 S-protein to epithelial cells by modification of host cell membrane proteins and specific glycosaminoglycans. Thus, OM-85 might be considered as an add-on for COVID-19 therapy.

IRF7-Associated Immunophenotypes Have Dichotomous Responses to Virus/Allergen Coexposure and OM-85-Induced Reprogramming

High risk for virus-induced asthma exacerbations in children is associated with an IRF7lo immunophenotype, but the underlying mechanisms are unclear. Here, we applied a Systems Biology approach to an animal model comprising rat strains manifesting high (BN) versus low susceptibility (PVG) to experimental asthma, induced by virus/allergen coexposure, to elucidate the mechanism(s)-of-action of the high-risk asthma immunophenotype. We also investigated potential risk mitigation via pretreatment with the immune training agent OM-85. Virus/allergen coexposure in low-risk PVG rats resulted in rapid and transient airways inflammation alongside IRF7 gene network formation. In contrast, responses in high-risk BN rats were characterized by severe airways eosinophilia and exaggerated proinflammatory responses that failed to resolve, and complete absence of IRF7 gene networks. OM-85 had more profound effects in high-risk BN rats, inducing immune-related gene expression changes in lung at baseline and reducing exaggerated airway inflammatory responses to virus/allergen coexposure. In low-risk PVG rats, OM-85 boosted IRF7 gene networks in the lung but did not alter baseline gene expression or cellular influx. Distinct IRF7-associated asthma risk immunophenotypes have dichotomous responses to virus/allergen coexposure and respond differentially to OM-85 pretreatment. Extrapolating to humans, our findings suggest that the beneficial effects OM-85 pretreatment may preferentially target those in high-risk subgroups.

Plantaricin NC8 αβ prevents Staphylococcus aureus-mediated cytotoxicity and inflammatory responses of human keratinocytes

Multidrug resistance bacteria constitue an increasing global health problem and the development of novel therapeutic strategies to face this challenge is urgent. Antimicrobial peptides have been proven as potent agents against pathogenic bacteria shown by promising in vitro results. The aim of this study was to characterize the antimicrobial effects of PLNC8 αβ on cell signaling pathways and inflammatory responses of human keratinocytes infected with S. aureus. PLNC8 αβ did not affect the viability of human keratinocytes but upregulated several cytokines (IL-1β, IL-6, CXCL8), MMPs (MMP1, MMP2, MMP9, MMP10) and growth factors (VEGF and PDGF-AA), which are essential in cell regeneration. S. aureus induced the expression of several inflammatory mediators at the gene and protein level and PLNC8 αβ was able to significantly suppress these effects. Intracellular signaling events involved primarily c-Jun via JNK, c-Fos and NFκB, suggesting their essential role in the initiation of inflammatory responses in human keratinocytes. PLNC8 αβ was shown to modulate early keratinocyte responses, without affecting their viability. The peptides have high selectivity towards S. aureus and were efficient at eliminating the bacteria and counteracting their inflammatory and cytotoxic effects, alone and in combination with low concentrations of gentamicin. We propose that PLNC8 αβ may be developed to combat infections caused by Staphylococcus spp.

Polyvalent Bacterial Lysate Protects Against Pneumonia Independently of Neutrophils, IL-17A or Caspase-1 Activation

Polyvalent bacterial lysates have been in use for decades for prevention and treatment of respiratory infections with reported clinical benefits. However, besides claims of broad immune activation, the mode of action is still a matter of debate. The lysates, formulated with the main bacterial species involved in respiratory infections, are commonly prepared by chemical or mechanical disruption of bacterial cells, what is believed influences the biological activity of the product. Here, we prepared two polyvalent lysates with the same composition but different method of bacterial cell disruption and evaluated their biological activity in a comparative fashion. We found that both bacterial lysates induce NF-kB activation in a MyD88 dependent manner, suggesting they work as TLR agonists. Further, we found that a single intranasal dose of any of the two lysates, is sufficient to protect against pneumococcal pneumonia, suggesting that they exert similar biological activity. We have previously shown that protection against pneumococcal pneumonia can also be induced by prior S. pneumoniae sub lethal infection or therapeutic treatment with a TLR5 agonist. Protection in those cases depends on neutrophil recruitment to the lungs, and can be associated with increased local expression of IL-17A. Here, we show that bacterial lysates exert protection against pneumococcal pneumonia independently of neutrophils, IL-17A or Caspase-1/11 activation, suggesting the existence of redundant mechanisms of protection. Trypsin-treated lysates afford protection to the same extent, suggesting that just small peptides suffice to exert the protective effect or that the molecules responsible for the protective effect are not proteins. Understanding the mechanism of action of bacterial lysates and deciphering the active components shall allow redesigning them with more precisely defined formulations and expanding their range of action.

Silence of the Lambs: The Immunological and Molecular Mechanisms of COVID-19 in Children in Comparison with Adults

Children infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can suffer from severe coronavirus disease 2019 (COVID-19). However, compared to adults and the elderly, susceptibility to SARS-CoV-2 infection in children seems to be lower; when infection does develop, most infected children remain asymptomatic or develop a mild disease. Understanding why children seem generally protected from severe COVID-19 and only rarely develop clinical conditions that can cause hospitalization, admission to the pediatric intensive care unit and death can be important. More details on the mechanism of action of SARS-CoV-2 could be defined. Moreover, the role played by children in virus diffusion should be better analyzed, and the development of effective preventive and therapeutic measures against COVID-19 could be favored. The main aim of this paper is to discuss the present knowledge on immunological and molecular mechanisms that could explain differences in COVID-19 clinical manifestations between children and adults. Literature analysis showed that although most children are clearly protected from the development of severe COVID-19, the reasons for this peculiarity are not fully understood. Developmental variations in immune system function together with the potential role of repeated antigen stimulation in the first periods of life on innate immunity are widely studied. As the few children who develop the most severe form of pediatric COVID-19 have certain alterations in the immune system response to SARS-CoV-2 infection, studies about the relationships between SARS-CoV-2 and the immune system of the host are essential to understand the reasons for the age-related differences in the severity of COVID-19.

[BCG, muramylpeptides, trained immunity (part II): a low molecular weight alternative to multicomponent bacterial immunostimulants for prevention of respiratory infections during a pandemic]

During a pandemic, nonspecific immunoprophylaxis of SARS-CoV-2 infection and other acute respiratory infections (ARI), which can worsen the course of COVID-19, is increasingly in demand in addition to specific immunization. BCG vaccine appears to be one of the candidate immunostimulants in this regard. At the same time, other microbe-derived preparations capable of inducing a state of trained immunity deserve attention. BCG and other bacterial immunostimulatory agents containing a large number of biologically active subunits have long been considered as objects of search for promising pharmacological substances. The review analyzes the linkages between BCG, mycobacterial adjuvants, bacterial lysates, trained immunity, muramylpeptides (MPs) and NOD2 receptors in light of the choice of a low molecular weight alternative to multicomponent bacterial immunostimulants for ARI prevention during the COVID-19 pandemic. The search for key molecules by which bacteria stimulate innate and adaptive immune responses proceeds in a spiral. On different loops of this spiral, MPs have repeatedly reproduced the nonspecific effects of multicomponent bacterial adjuvants, vaccines and immunostimulants. MPs and peptidoglycans containing MPs determine the adjuvant properties of the cell walls of mycobacteria and their peptide-glycolipid fraction (wax D). MPs were able to replace Mycobacterium tuberculosis in complete Freunds adjuvant. MPs determine the NOD2-dependent ability of BCG to induce trained immunity. Probably, MPs provide NOD2-mediated long-term prophylactic action of bacterial lysates. All of the above has prompted revisiting the previously obtained evidence of the efficacy of glucosaminylmuramyl dipeptide (GMDP) as a NOD2 agonist in treatment/prevention of respiratory infections. We speculate here that MPs, in particular GMDP, at rational dosing regimens will be able to reproduce many aspects of the nonspecific effects of BCG and multicomponent bacterial immunostimulants in preventing ARI during the COVID-19 pandemic and in the post-pandemic period.

Bacterial lysate therapy for the prevention of wheezing episodes and asthma exacerbations: a systematic review and meta-analysis

Wheezing and asthma are a growing cause of morbidity in children and adults. Treatment is aimed at prevention of disease exacerbations and preservation of lung function. Respiratory viruses are involved in ∼40-60% of exacerbations. Bacterial lysates prevent recurrent respiratory tract infections and might reduce exacerbations. Moreover, immunomodulatory effects have been observed in human and animal studies. Here we aimed to assess the effects of bacterial lysate therapy on preschool wheezing episodes and asthma exacerbation frequency. We performed a systematic literature review based on the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) statement and a meta-analysis using Cochrane Review Manager. Out of 2016 retrieved articles, 22 studies were included, of which five provided sufficient data for a meta-analysis.The use of bacterial lysates showed a decrease of both wheezing episodes (mean difference -2.35 (-3.03- -1.67), p<0.001) and asthma exacerbations in children (mean difference -0.90 (-1.23- -0.57), p<0.001). Additionally, antibiotic use was reduced, and the duration of wheezing episodes was also decreased. No data for adults with asthma are currently available. The immunomodulatory effect seems to be dependent on increased T-helper (Th)1-cell activation and Th2-cell suppression.These favourable effects of bacterial lysates indicate that they show promise as add-on therapy in preschool wheezing and childhood asthma.

Involvement of Mesenchymal Stem Cells in Oral Mucosal Bacterial Immunotherapy

Recent clinical observations indicate that bacterial vaccines induce cross-protection against infections produced by different microorganisms. MV130, a polyvalent bacterial sublingual preparation designed to prevent recurrent respiratory infectious diseases, reduces the infection rate in patients with recurrent respiratory tract infections. On the other hand, mesenchymal stem cells (MSCs) are key cell components that contribute to the maintenance of tissue homeostasis and exert both immunostimulatory and immunosuppressive functions. Herein, we study the effects of MV130 in human MSC functionality as a potential mechanism that contributes to its clinical benefits. We provide evidence that during MV130 sublingual immunization of mice, resident oral mucosa MSCs can take up MV130 components and their numbers remain unchanged after vaccination, in contrast to granulocytes that are recruited from extramucosal tissues. MSCs treated in vitro with MV130 show an increased viability without affecting their differentiation potential. In the short-term, MSC treatment with MV130 induces higher leukocyte recruitment and T cell expansion. In contrast, once T-cell activation is initiated, MV130 stimulation induces an up-regulated expression of immunosuppressor factors in MSCs. Accordingly, MV130-primed MSCs reduce T lymphocyte proliferation, induce the differentiation of dendritic cells with immunosuppressive features and favor M2-like macrophage polarization, thus counterbalancing the immune response. In addition, MSCs trained with MV130 undergo functional changes, enhancing their immunomodulatory response to a secondary stimulus. Finally, we show that MSCs are able to uptake, process and retain a reservoir of the TLR ligands derived from MV130 digestion which can be subsequently transferred to dendritic cells, an additional feature that also may be associated to trained immunity.

Prevention of New Respiratory Episodes in Children with Recurrent Respiratory Infections: An Expert Consensus Statement

In healthy infants and young children, the development of respiratory tract infections (RTIs) is extremely common. In this paper, we present an international consensus of the available approaches for the prevention of recurrent RTIs in children, including the atopic/allergic ones as well as those with asthma. Few convincing measures for reducing the frequency and clinical relevance of recurrent respiratory episodes in RTI-prone children have been developed until now. Among the most recently suggested measures, immunotherapy is attractive, but only for OM-85 is there a sufficient number of well-conducted clinical trials confirming efficacy in RTIs prevention with an adequate safety profile. In the case of probiotics, it is not clear which bacteria can offer the best results and which dosage and schedule of administration are the most effective. The problems of dosage and the schedule of administration are not solved also for vitamin D, despite some promising efficacy results. While we wait for new knowledge, the elimination or reduction as much as possible of the environmental factors that favor RTIs, vaccination when available and/or indicated, and the systematic application of the traditional methods for infection prevention, such as hand washing, remain the best measures to prevent recurrent infections in RTI-prone children.

Epithelial dysfunction, respiratory infections and asthma: the importance of immunomodulation. A focus on OM-85

INTRODUCTION

Damage to the respiratory epithelium, is often a multifactorial phenomenon. The risk for developing a damage in respiratory epithelium and recurrent respiratory infections may vary among individuals. Preventive measures are based on strengthening the immune function, thus increasing the natural response to pathogens. Immunomodulatory agents are: i. synthetic molecules; ii. Probiotics, prebiotics, symbiotics; iii. Lysates, bacterial extracts immunomodulators: OM-85, RU 41740, D53; iv. Trace elements, vitamins. OM-85 is used for the prevention of recurrent respiratory tract infections and/or exacerbations both in adults and children, showing a good efficacy and safety profile. Its active principle, an extract of bacterial lysates isolated from 21 known respiratory pathogenic strains, shows protection against airway infections of bacterial and viral origin.

AREAS COVERED

This non-systematic review focuses on bacterial lysates and in particular on OM-85 and its effects on respiratory epithelium function and activity in asthma respiratory infections. Studies were selected by PubMed search of "bacterial lysate" or "OM-85" and "respiratory epithelium" or "respiratory infections", from 1993 to 2019.

EXPERT OPINION

Results highlight the ability of OM-85 to trigger immunomodulatory and protective immune responses against different pathogens in vivo, including influenza and respiratory syncytial virus as well bacterial superinfection following influenza.

Viral infections and wheezing-asthma inception in childhood: is there a role for immunomodulation by oral bacterial lysates?

Severe and recurrent infections of the respiratory tract in early childhood constitute major risk factors for the development of bronchial hyper-responsiveness and obstructive respiratory diseases in later life. In the first years of life, the vast majority of respiratory tract infections (RTI) leading to wheezing and asthma are of a viral origin and severity and recurrence are the consequence of a greater exposure to infectious agents in a period when the immune system is still relatively immature. Therefore, boosting the efficiency of the host immune response against viral infections seems to be a rational preventative approach. In the last decades it has been demonstrated that living in farm environments, i.e. early-life exposure to microbes, may reduce the risk of allergic and infectious disorders, increasing the immune response efficacy. These findings have suggested that treatment with bacterial lysates could promote a nonspecific immunomodulation useful in the prevention of recurrent RTIs and of wheezing inception and persistence. Experimental and clinical studies showing the reduction of RTI frequency and severity in childhood and elucidating the involved mechanisms can support this hypothesis.

[The efficacy of OM85-BV in the treatment of recurrent upper respiratory tract infection with adenoid hypertrophy and the preliminary exploration of potential therapeutic mechanism]

Objective:To observe the efficacy of OM85-BV in the treatment of recurrent upper respiratory tract infection with adenoid hypertrophy and to explore its possible mechanism. Method:Four hundred and forty-eight children with recurrent upper respiratory tract infection and adenoid hypertrophy were collected. Three hundred and twenty-six patients in the control group were treated with conventional drugs, and one hundred and twenty-two patients in the observation group were treated with OM85-BV+conventional drugs, and the treatment lasted 12 weeks. The sleep obstructive symptoms of adenoid hypertrophy were scored according to OSA-18 before and after the treatment respectively（0, 6, 12 weeks）. The symptoms scores and effective rate of treatment between the study and the control group were compared. The patients in the control group and the observation group who were unresponsive to drug treatment received surgery after 12 weeks of drug treatment. The levels of serum IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ and IgE, the ratio of serum CD3, CD4, CD8 in lymphocytes and the ratio of CD4/CD8 were compared between the study and the control group before operation. The levels of HBD-2, IFN-γ, IL-4, IL-6 cytokines in the adenoid were compared between the control group and the observation group. The expression and distribution of adenoid HBD-2, IFN-γ, IL-4, IL-6 were compared between the control group and the observation group. Result:After 12 weeks of treatment, the total effective rate of the observation group was significantly higher than that of the control group, and the improvement of sleep respiratory obstruction symptoms of children with recurrent upper respiratory tract infection and adenoid hypertrophy was also much better than that of the control group. The serum IFN-γ of the observation group was significantly higher than that of the control group, and there was no significant difference in serum IL-2, IL-4, IL-6, IL-10, TNF, IgE between the observation group and the control group. There was no significant difference in serum CD3, CD4, CD8 and CD4/CD8 between the observation group and the control group. In the observation group, the adenoid HBD-2 was significantly higher but IL-4, IFN-γ were significantly lower than that in the control group, and IL-6 had no significant difference compared with the control group. Conclusion:OM85-BV can significantly improve the sleep apnea symptoms but can not rise the level of immune lymphocytes in children with adenoid hypertrophy and recurrent upper respiratory tract infection.OM85-BV can improve the Th1 immune response, enhancing the ability of human body to fight against pathogens and induce the release of HBD-2, increasing the resistance to microorganisms, reducing the bacteria aggregation, weakening the local inflammatory response in adenoids.

Paediatric Recurrent Ear, Nose and Throat Infections and Complications: Can We Do More?

Recurrent respiratory tract infections (rRTIs), of which there are three main groups-otitis media, tonsillitis and sinusopathies-are very common in paediatric populations and are associated with significant morbidity and mortality due to complications. These infections substantially reduce quality of life for paediatric patients and their families and are a significant personal, medical and economic burden on the patients, the patients' families and the healthcare system. Most rRTIs are of viral origin; however, indiscriminate use of antibiotics in their treatment has led to development of bacterial resistance. Effective management of rRTIs to reduce the burden of disease and to avoid overuse of antibiotics has become a great therapeutic challenge. New strategies for the management of paediatric rRTIs include focus on prevention using non-specific immunomodulators to boost the body's natural defences against infection and to downregulate infection- and allergen-induced airway inflammation. The oral immunomodulator, OM-85, a bacterial lysate, acts on the innate and adaptive branches of the immune system, conferring protection against viral and bacterial infections, and controls inflammation, thereby reducing tissue damage. OM-85 has demonstrated good tolerability and clinical efficacy in reducing the number and duration of RTIs in children with recurrent airway infections. It has also been reported to reduce the use of concomitant medications, including antibiotics, time to cure and school absenteeism. OM-85 is efficacious and well tolerated when administered concomitantly with inactivated influenza vaccine (IIV) and has been shown to reduce wheezing attacks induced by RTI in young children. Clinical results show that the greater the risk of rRTIs, the greater the benefit with OM-85. OM-85 may be considered a promising tool to add to the limited armamentarium of the ear, nose and throat (ENT) physician dealing with rRTIs and their complications, such as recurrent wheeze and asthma inception.

MyD88 mediates colorectal cancer cell proliferation, migration and invasion via NF‑κB/AP‑1 signaling pathway

The role of myeloid differentiation factor 88 (MyD88) in malignant tumors is largely unknown. Therefore, in this study, we aimed to examine the function and underlying mechanism of MyD88 in colorectal carcinoma in vitro using SW480 and HCT116 cell lines and in vivo using a nude mouse model. SW480 and HCT116 cells were infected with a lentiviral-based effective MyD88 siRNA virus. CCK-8 and colony formation assay were used to assess cell proliferation. Transwell and scratch assays were used to test the migration of colorectal cancer cells, and the Transwell assay was further used to analyze the invasiveness of colorectal cancer cells. Western blotting was performed to analyze the underlying mechanism of MyD88 regulation. In vitro experiments demonstrated that silencing MyD88 in SW480 and HCT116 cells markedly suppressed growth and invasion. Furthermore, MyD88 knockdown affected the MyD88-NF-κB/AP-1 signaling pathways in SW480 and HCT116 cells. In vivo, MyD88 knockdown inhibited tumor growth in a HCT116 cell subcutaneous nude model. We found that knockdown of the MyD88 gene can affect proliferation, invasion, and migration of colorectal cancer cells. We further verified that MyD88 knockdown can reduce the activity of NF-κB and AP-1 pathways. These results show that MyD88 gene plays an important role in promoting colorectal cancer, and thus can be exploited as a potential diagnostic and prognostic biomarker for colorectal cancer.

Immunity-targeted approaches to the management of chronic and recurrent upper respiratory tract disorders in children

Background

Upper respiratory tract infections (URTIs), including rhinitis, nasopharyngitis, tonsillitis and otitis media (OM), comprise of 88% of total respiratory infections, especially in children. Therefore effective prevention and treatment of RTIs remain a high priority worldwide. Preclinical and clinical data highlight the rationale for the use and effectiveness of immunity‐targeted approaches, including targeted immunisations and non‐specific immunomodulation in the prevention and management of recurrent upper RTIs.

Objective of review

The idea of this review was to summarise the current evidence and address key questions concerning the use of conservative and immunity‐targeted approaches to recurrent and chronic URTIs, with a focus on the paediatric population.

Search strategy/Evaluation method

Literature searches were conducted in March 2017 and updated in September 2017 using: Academic Search Complete; CENTRAL; Health Source: Nursing/Academic Edition; MEDLINE; clinicaltrials.gov; and Cochrane databases. In total, 84 articles were retrieved and reviewed. Two independent researchers focused on primary and secondary endpoints in systematic reviews, meta‐analyses and randomised, controlled trials, using immunity‐directed strategies as the control group or within a subpopulation of larger studies. Existing guidelines and interventional/observational studies on novel applications were also included.

Results

Children are particularly susceptible to RTIs due to the relative immaturity of their immune systems, as well as other potential predisposing factors such as day care attendance and/or toxic environmental factors (eg increased pathogenic microbial exposure and air pollutants). Recurrent URTIs can affect otherwise healthy children, leading to clinical sequelae and complications, including the development of chronic conditions or the need for surgery. Available pre‐clinical and clinical data highlight the rationale for the use and effectiveness of immunity‐targeted approaches, including targeted immunisations (flu and pneumococcal vaccines) and non‐specific immunomodulation (bacterial lysates), in the prevention and management of recurrent croup, tonsillitis, otitis media, recurrent acute rhinosinusitis and chronic rhinosinusitis.

Conclusions

In this review, we summarise the current evidence and provide data demonstrating that some immunity‐targeted strategies, including vaccination and immunomodulation, have proved effective in the treatment and prevention of recurrent and chronic URTIs in children.

The PDE4 inhibitor CHF6001 modulates pro-inflammatory cytokines, chemokines and Th1- and Th17-polarizing cytokines in human dendritic cells

Phosphodiesterase 4 (PDE4) inhibitors are used to treat autoimmune and inflammatory diseases, such as psoriasis and chronic obstructive pulmonary disease (COPD). CHF6001 is a novel, potent and selective inhaled PDE4 inhibitor in development for the treatment of COPD. When tested in vitro on human dendritic cells (DCs), CHF6001 decreased the release of pro-inflammatory cytokines (TNF-α and IL-6), chemokines (CXCL8, CCL3, CXCL10 and CCL19) and of Th1- and Th17-polarizing cytokines (IL-12, IL-23 and IL-1β). In contrast to β-methasone, a reference steroid anti-inflammatory drug, CHF6001 increased the secretion of CCL22, a Th2 recruiting chemokine, and the expression of the lymph node homing receptor CCR7. Accordingly, the migration of DCs to CCR7 ligands was increased, while migration to pro-inflammatory chemokines was decreased. Of note, the action of CHF6001 was apparently mediated by a promoter-specific decrease in NF-κB p65 recruitment, independent of perturbation of LPS signalling or NF-κB nuclear translocation. Our results indicate that CHF6001 can modulate DC pro-inflammatory Th1/Th17 polarizing potential by fine tuning the transcriptional activity of the master inflammatory transcription factor NF-κB. Therefore, CHF6001 may prove useful to control Th1/Th17-polarized inflammatory diseases such as COPD.

Evidence that a primary anti-viral stimulation of the immune response by OM-85 reduces susceptibility to a secondary respiratory bacterial infection in mice

BACKGROUND

Viral respiratory infections may promote bacterial super-infection decreasing the host immune response efficiency. However, using a mice model we recently demonstrated that preventive treatment with the bacterial extract OM-85 reduces the susceptibility to a secondary Streptococcus (S.) pneumoniae infection after influenza virus (I.V.) challenge.

METHODS

To better characterize the efficacy of OM-85 against S. pneumoniae super-infection, a post-hoc analysis was conducted, comparing efficacy (survival) and morbidity signs (clinical score, body temperature and weight loss) in the OM-85 and the control (BLANC) groups of mice after: a) I.V. infection; b) primary S. pneumoniae infection and c) post-I.V. S. pneumoniae super-infection.

RESULTS

After a sublethal I.V. dose, all mice stayed alive at day 5 and no differences in morbidity signs were detected between the OM-85 and the BLANC groups. However, OM-85 pretreatment led to a significantly reduction of the viral load in the lung on day 5 post viral infection and, on day 10, reduced neutrophilic inflammation while increasing influenza-specific CD8 + T-cell proportion in the airways. Conversely to viral infection, exposure to S. pneumoniae induced a dramatic reduction of survival, with no mice surviving on day 3 post infection in the BLANC group, whereas a partial protective effect was observed in OM-85 pre-treated mice (20% of mice surviving at day 3, and 10% at day 4 and 5). The morbidity data substantiated the survival results. Interestingly, in the "super-infection" study, when mice were exposed to a sublethal I.V. dose followed by a secondary S. pneumoniae infection, all mice died by day 4 in the BLANC group. In contrast, in the OM-85 treated group, the survival rate was 70% at day 4 and still 50% at day 5, with positive effects on the clinical scores and on the body temperature already detectable at days 1 and 2.

CONCLUSIONS

The efficacy of OM-85 pre-treatment against S. pneumoniae super-infection reflects a strong and immediate immune reaction from the host, an event that can be explained in part by a "non-specific" activation of the immune system, a positive "immune effect" of the general OM-85- induced immune response against I.V.

Nonspecific immunomodulators for recurrent respiratory tract infections, wheezing and asthma in children: a systematic review of mechanistic and clinical evidence

PURPOSE OF REVIEW

To provide an overview of the mechanistic and clinical evidence for the use of nonspecific immunomodulators in paediatric respiratory tract infection (RTI) and wheezing/asthma prophylaxis.

RECENT FINDINGS

Nonspecific immunomodulators have a long history of empirical use for the prevention of RTIs in vulnerable populations, such as children. The past decade has seen an increase in both the number and quality of studies providing mechanistic and clinical evidence for the prophylactic potential of nonspecific immunomodulators against both respiratory infections and wheezing/asthma in the paediatric population. Orally administered immunomodulators result in the mounting of innate and adaptive immune responses to infection in the respiratory mucosa and anti-inflammatory effects in proinflammatory environments. Clinical data reflect these mechanistic effects in reductions in the recurrence of respiratory infections and wheezing events in high-risk paediatric populations. A new generation of clinical studies is currently underway with the power to position the nonspecific bacterial lysate immunomodulator OM-85 as a potential antiasthma prophylactic.

SUMMARY

An established mechanistic and clinical role for prophylaxis against paediatric respiratory infections by nonspecific immunomodulators exists. Clinical trials underway promise to provide high-quality data to establish whether a similar role exists in wheezing/asthma prevention.

Viral infections in wheezing disorders

Over the past year, studies into virus-induced wheeze in children have shifted towards investigations that examine the mechanisms by which respiratory viruses cause wheeze and an increase in studies examining the effects of novel interventions to reduce wheezing exacerbations. Studies on rhinovirus species (RV)-C infection have found that this is associated with a decrease in expression of CDHR3, the cellular receptor specific for this virus, and a decrease in interferon-β expression, both of which are likely to favour RV-C infection. Recent clinical trials in children have found a decrease in wheezing exacerbations with both anti-respiratory syncytial virus antibody and anti-immunoglobulin E antibody therapy, and a clinical trial of prednisolone in children with their first RV-induced wheeze showed that only those with an RV viral count >7000 copies·mL−1responded. Further studies on the effects of bacterial lysates on immune system function continue to support the potential of this approach to reduce virus-induced wheezing exacerbations in children. These studies and many previous investigations into immunomodulation using bacterial lysates have led to the funding and commencement of a large study in which long-term administration of a bacterial lysate in young children will be assessed for its ability to prevent asthma.

Human dendritic cells activated with MV130 induce Th1, Th17 and IL-10 responses via RIPK2 and MyD88 signalling pathways

Recurrent respiratory tract infections (RRTIs) are the first leading cause of community- and nosocomial-acquired infections. Antibiotics remain the mainstay of treatment, enhancing the potential to develop antibiotic resistances. Therefore, the development of new alternative approaches to prevent and treat RRTIs is highly demanded. Daily sublingual administration of the whole heat-inactivated polybacterial preparation (PBP) MV130 significantly reduced the rate of respiratory infections in RRTIs patients, however, the immunological mechanisms of action remain unknown. Herein, we study the capacity of MV130 to immunomodulate the function of human dendritic cells (DCs) as a potential mechanism that contribute to the clinical benefits. We demonstrate that DCs from RRTIs patients and healthy controls display similar ex vivo immunological responses to MV130. By combining systems biology and functional immunological approaches we show that MV130 promotes the generation of Th1/Th17 responses via receptor-interacting serine/threonine-protein kinase-2 (RIPK2)- and myeloid-differentiation primary-response gene-88 (MyD88)-mediated signalling pathways under the control of IL-10. In vivo BALB/c mice sublingually immunized with MV130 display potent systemic Th1/Th17 and IL-10 responses against related and unrelated antigens. We elucidate immunological mechanisms underlying the potential way of action of MV130, which might help to design alternative treatments in other clinical conditions with high risk of recurrent infections.

Broncho Vaxom (OM-85) modulates rhinovirus docking proteins on human airway epithelial cells via Erk1/2 mitogen activated protein kinase and cAMP

BACKGROUND

Bronchial epithelial cells (BEC) are primary target for Rhinovirus infection through attaching to cell membrane proteins. OM-85, a bacterial extract, improves recovery of asthma and COPD patients after viral infections, but only part of the mechanism was addressed, by focusing on defined immune cells.

OBJECTIVE

We therefore determined the effect of OM-85 on isolated primary human BEC of controls (n = 8), asthma patients (n = 10) and COPD patients (n = 9).

METHODS

BEC were treated with OM-85 alone (24 hours) or infected with Rhinovirus. BEC survival was monitored by manual cell counting and Rhinovirus replication by lytic activity. Immuno-blotting and ELISA were used to determine the expression of Rhinovirus interacting proteins: intracellular adhesion molecule (ICAM), major histocompatibility complex class II (MHC-2), complement component C1q receptor (C1q-R), inducible T-Cell co-stimulator (ICOS), its ligand ICOSL, and myeloid differentiation primary response gene 88 (Myd88); as well as for signal transducers Erk1/2, p38, JNK mitogen activated protein kinases MAPK), and cAMP.

RESULTS

OM-85 significantly reduced Rhinovirus-induced BEC death and virus replication. OM-85 significantly increased the expression of virus interacting proteins C1q-R and β-defensin in all 3 probes and groups, which was prevented by either Erk1/2 MAPK or cAMP inhibition. In addition, OM-85 significantly reduced Rhinovirus induced expression of ICAM1 involving p38 MAPK. In BEC OM-85 had no significant effect on the expression of ICOS, ICOSL and MHC-2 membrane proteins nor on the adaptor protein MyD88.

CONCLUSION

The OM-85-induced increased of C1q-R and β-defensin, both important for antigen presentation and phagocytosis, supports its activity in host cell's defence against Rhinovirus infection.

Protection against maternal infection-associated fetal growth restriction: proof-of-concept with a microbial-derived immunomodulator

Infection-associated inflammatory stress during pregnancy is the most common cause of fetal growth restriction and/or miscarriage. Treatment strategies for protection of at-risk mothers are limited to a narrow range of vaccines, which do not cover the bulk of the common pathogens most frequently encountered. Using mouse models, we demonstrate that oral treatment during pregnancy with a microbial-derived immunomodulator (OM85), currently used clinically for attenuation of infection-associated airway inflammatory symptoms in infants-adults, markedly reduces risk for fetal loss/growth restriction resulting from maternal challenge with bacterial lipopolysaccharide or influenza. Focusing on LPS exposure, we demonstrate that the key molecular indices of maternal inflammatory stress, notably high levels of RANTES, MIP-1α, CCL2, KC, and G-CSF (granulocyte colony-stimulating factor) in gestational tissues/serum, are abrogated by OM85 pretreatment. Systems-level analyses conducted in parallel using RNASeq revealed that OM85 pretreatment selectively tunes LPS-induced activation in maternal gestational tissues for attenuated expression of TNF, IL1, and IFNG-driven proinflammatory networks, without constraining Type1-IFN-associated networks central to first-line antimicrobial defense. This study suggests that broad-spectrum protection-of-pregnancy against infection-associated inflammatory stress, without compromising capacity for efficient pathogen eradication, represents an achievable therapeutic goal.

OM-85 is an immunomodulator of interferon-β production and inflammasome activity

The inflammasome–IL-1 axis and type I interferons (IFNs) have been shown to exert protective effects upon respiratory tract infections. Conversely, IL-1 has also been implicated in inflammatory airway pathologies such as asthma and chronic obstructive pulmonary disease (COPD). OM-85 is a bacterial extract with proved efficacy against COPD and recurrent respiratory tract infections, a cause of co-morbidity in asthmatic patients. We therefore asked whether OM-85 affects the above-mentioned innate immune pathways. Here we show that OM-85 induced interferon-β through the Toll-like receptor adaptors Trif and MyD88 in bone marrow-derived dendritic cells. Moreover, it exerted a dual role on IL-1 production; on the one hand, it upregulated proIL-1β and proIL-1α levels in a MyD88-dependent manner without activating the inflammasome. On the other hand, it repressed IL-1β secretion induced by alum, a well-known NLRP3 activator. In vivo, OM-85 diminished the recruitment of inflammatory cells in response to peritoneal alum challenge. Our findings therefore suggest that OM-85 favors a protective primed state, while dampening inflammasome activation in specific conditions. Taken together, these data bring new insights into the mechanisms of OM-85 action on innate immune pathways and suggest potential explanations for its efficacy in the treatment of virus-induced airway diseases.

Mechanical stretch regulates microRNA expression profile via NF-κB activation in C2C12 myoblasts

MicroRNAs (miRNAs/miRs) and nuclear factor (NF)-κB activation are involved in mechanical stretch-induced skeletal muscle regeneration. However, there are a small number of miRNAs that have been reported to be associated with NF‑κB activation during mechanical stretch-induced myogenesis. In the present study, C2C12 myoblasts underwent cyclic mechanical stretch in vitro, to explore the relationship between miRNA expression and NF‑κB activation during stretch-mediated myoblast proliferation. The results revealed that 10% deformation, 0.125 Hz cyclic mechanical stretch could promote myoblast proliferation. The miRNA expression profile was subsequently altered; miR‑500, ‑1934, ‑31, ‑378, ‑331 and ‑5097 were downregulated, whereas miR‑1941 was upregulated. These miRNAs were all involved in stretch‑mediated myoblast proliferation. Notably, the expression of these miRNAs was reversed following treatment of 0.125 Hz mechanically stretched C2C12 cells with NF‑κB inhibitors, which was accompanied by C2C12 cell growth suppression. Therefore, the present study is the first, to the best of our knowledge, to demonstrate that the NF‑κB‑dependent miRNA profile is associated with mechanical stretch-induced myoblast proliferation.

The cost-effectiveness of OM-85 in managing respiratory tract infections in China

OBJECTIVES

To demonstrate the health economic impact of OM-85, a bacterial lysates based immunostimulant, for its approved indications in China.

METHODS

A cost-effectiveness decision tree model was constructed comparing OM-85 with the best supportive care/placebo therapy for managing the acute exacerbation of chronic bronchitis and rhinosinusitis in the Chinese population. Clinical efficacy and adverse events (AE) data were included in the model based on a thorough literature review. All localized direct treatment costs, including drug cost, AE costs, and medical treatment costs for underlining diseases were included from a Chinese third party payer perspective. A Key Opinion Leaders (KOL) survey was conducted with 20 senior physicians specialized in respiratory, ENT, allergy, and immunology fields from tertiary hospitals in Beijing, Shanghai, Guangzhou, Hangzhou, Shenyang, and Wuhan to validate the local treatment costs. Incremental cost-effectiveness ratio (ICER) was calculated based on the above efficacy and cost information.

RESULTS

OM-85 is a cost-effective therapy when compared with placebo (standard care). OM-85 can treat/prevent one additional full episode exacerbation of chronic bronchitis and one additional full episode exacerbation of rhinosinusitis with only additional costs of RMB 653 and RMB 1182.84, respectively. In comparison, each acute exacerbation of chronic bronchitis will cost RMB 4510.10, and each acute exacerbation of rhinosinuisitis will cost RMB 1807.21 in a Chinese clinical management setting. One-way sensitivity analyses were performed and the ICER result was demonstrated to be consistent.

CONCLUSIONS

OM 85 reduces acute exacerbations among patients with chronic bronchitis and chronic rhinosinusitis when compared with Placebo (standard care). From a Chinese payer perspective, OM 85 is a cost-effective therapy in the clinical management of both chronic bronchitis and rhinosinusitis in the adult population.

Enhanced Mucosal Antibody Production and Protection against Respiratory Infections Following an Orally Administered Bacterial Extract

Secondary bacterial infections following influenza infection are a pressing problem facing respiratory medicine. Although antibiotic treatment has been highly successful over recent decades, fatalities due to secondary bacterial infections remain one of the leading causes of death associated with influenza. We have assessed whether administration of a bacterial extract alone is sufficient to potentiate immune responses and protect against primary infection with influenza, and secondary infections with either Streptococcus pneumoniae or Klebsiella pneumoniae in mice. We show that oral administration with the bacterial extract, OM-85, leads to a maturation of dendritic cells and B-cells characterized by increases in MHC II, CD86, and CD40, and a reduction in ICOSL. Improved immune responsiveness against influenza virus reduced the threshold of susceptibility to secondary bacterial infections, and thus protected the mice. The protection was associated with enhanced polyclonal B-cell activation and release of antibodies that were effective at neutralizing the virus. Taken together, these data show that oral administration of bacterial extracts provides sufficient mucosal immune stimulation to protect mice against a respiratory tract viral infection and associated sequelae.

Broncho-Vaxom attenuates allergic airway inflammation by restoring GSK3β-related T regulatory cell insufficiency

Background

Oral administration of bacterial extracts (eg, Broncho-Vaxom (BV)) has been proposed to attenuate asthma through modulating Treg cells. However, the underlying mechanism has not been fully characterized. This study sought to assess the effects of oral administration of BV on GSK-3β expression and Treg cells in ovalbumin (OVA)-induced asthmatic mice models.

Method

Asthmatic mice models were established with OVA challenge and treated with oral administration of BV. Next, infiltration of inflammatory cells including eosinophil and neutrophils, mucous metaplasia, levels of Th1/Th2/Treg-typed cytokines and expression of GSK3β and Foxp3 were examined in asthmatic mice models by histological analysis, Bio-Plex and western blot, respectively. Moreover, the frequencies of Treg cells were evaluated in cultured splenocytes by flow cytometry in the presence of BV or GSK3β siRNA interference.

Results

We found significant decrease of infiltrated inflammatory cells in bronchoalveolar lavage fluid (BALF) in asthmatic mice models after oral administration of BV. Oral administration of BV was shown to significantly suppress mucus metaplasia, Th2-typed cytokine levels and GSK3β expression while increasing Foxp3 production in asthmatic mice models. Moreover, BV significantly enhanced GSK3β-related expansion of Treg cells in cultured spleen cells in vitro.

Conclusion

Our findings provide evidence that oral administration of BV is capable of attenuating airway inflammation in asthmatic mice models, which may be associated with GSK3β-related expansion of Treg cells.