Distinct effects of Broncho-Vaxom (OM-85 BV) on gp130 binding cytokines

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.

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.

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.

Prospective, randomized comparison of OM-85 BV and a prophylactic antibiotic in children with recurrent infections and immunoglobulin A and/or G subclass deficiency

BACKGROUND

Patients with immunoglobulin (Ig)A and/or IgG subclass deficiency may be asymptomatic or may have recurrent, mainly respiratory infections.

OBJECTIVE

This study compared the clinical efficacy and tolerability of prophylactic therapy with either the oral immunomodulator bacterial extract OM-85 BV or benzathine penicillin G (BPG) in the prevention of recurrent infections in symptomatic patients.

METHODS

In this 26-month, prospective, randomized study conducted at the Department of Pediatric Immunology, Ege University (Izmir, Turkey), children aged 1 to 12 years with recurrent infections and IgA and/or IgG subclass deficiency were enrolled. After an initial 12-month control period, patients were randomized to receive OM-85 BV or BPG. OM-85 BV (3.5-mg capsule) was given once daily for the first 10 days of each month for the first 3 months of the study. IM injections of BPG were given at a dose of 1.2 million units (for patients with body weight > 27 kg) or at a half-dose (for patients with body weight ≤27 kg) every 3 weeks for 12 months. In nonresponders (ie, those who continued to have recurrent infections at 12-month follow-up), IV immunoglobulin (IVIG) replacement therapy at 400 mg/kg body weight was given every 4 weeks for an additional 12 months. The results of IVIG therapy were assessed by the authors using clinical observation. Adverse effects and adverse drug reactions were documented by the authors for each vaccine, prophylactic therapy, and IVIG.

RESULTS

A total of 91 children (56 boys, 35 girls; mean [SD] age at the start of the control period, 46.4 [31.0] months) were enrolled. Of these, 44 were randomized to the OM-85 BV group and 47 to the BPG group. The year before prophylactic therapy, the mean (SD) number of reported infections was 10.7 (3.6) and the mean (SD) number of antibiotic courses was 9.7 (3.6) (OM-85 BV group: mean [SD] number of reported infections, 10.5 [3.3]; mean (SD) number of antibiotic courses, 9.3 [3.3]; BPG group: mean [SD] number of reported infections, 10.8 [3.9], mean (SD) number of antibiotic courses, 10.1 [3.9]). At 12 months, the number of infections and antibiotic courses decreased significantly in the entire study population, but the between-group difference was not significant. Five patients in each group (OM-85 BV group, 11.4%; BPG group, 10.6%) were considered nonresponders and received IVIG treatment. Compared with responders, nonresponders were significantly younger (mean [SD] age, 34.40 [21.70] months vs 52.65 [30.52] months; P = 0.036) and had lower serum IgG (P<0.001), IgG1 (P = 0.006), IgG2 (P = 0.003), IgG3 (P = 0.035), and IgM (P = 0.008) levels and antibody responses to tetanus toxoid and Haemophilus influenzae type b (Hib) vaccines (P = 0.036 and 0.013, respectively). At 12-month follow-up, a protective effect of the prophylactic IVIG therapy was seen, with a statistically significant reduction in the number of infections to 3.3 (2.4) and in the number of antibiotic courses to 2.7 (2.5) (both P = 0.005).

CONCLUSIONS

In this study population of children with recurrent infections and IgA and/or IgG subclass deficiency, prophylactic therapy with either OM-85 BV or an antibiotic significantly decreased the number of infections per year. In addition, nonresponders benefited from IVIG replacement therapy.

Sublingual therapeutic immunization with a polyvalent bacterial preparation in patients with recurrent respiratory infections: immunomodulatory effect on antigen-specific memory CD4+ T cells and impact on clinical outcome

Recurrent respiratory tract infections (RRTIs) are common clinical conditions in individuals with alterations of the immune function. A prospective open pilot study in a cohort of patients with RRTIs has been performed to assess whether sublingual immunization with a polyvalent bacterial vaccine could exert an immunomodulatory effect on the antigen-specific immunological responses and have an impact on the clinical outcome. Seventeen patients with RRTIs were recruited. An oral polyvalent bacterial preparation (Bactek®) was administered to all patients daily for 6 months. Immunological assessment was performed at baseline and at the end of immunization. Immunological measurements included: T cell-specific proliferations of CD3+CD4+ and CD3+CD8+ to Bactek® antigens, total immunoglobulin levels, antibodies to pneumococcal polysaccharide and tetanus toxoid and B, T and natural killer (NK) cell subsets. There was a significant increase in the proliferative capacity of CD3+CD4+ T cells specific to Bactek® antigens at month 6 in comparison to baseline (P < 0·0001). A significant increase in total CD3+ T cells was also observed (P < 0·05). No significant differences were observed between baseline and month 6 in levels of total immunoglobulins, specific antibodies and B, T or NK cell subsets. A significant reduction in the patient's rate of RRTIs was observed compared with 1 year prior to initiation of therapy (P < 0·0001). The results demonstrate that long-term administration of a sublingual polyvalent bacterial preparation in patients with RRTIs exerts an immune stimulating effect on CD4+ T helper cell responses to bacterial antigens which could be associated with clinical benefit.

Rhinovirus infection induces expression of airway remodelling factors in vitro and in vivo

BACKGROUND AND OBJECTIVE

A hallmark of asthma is airway remodelling, which includes increased deposition of extracellular matrix (ECM) protein. Viral infections may promote the development of asthma and are the most common causes of asthma exacerbations. We evaluated whether rhinovirus (RV) infection induces airway remodelling, as assessed by ECM deposition.

METHODS

Primary human bronchial epithelial cells and lung parenchymal fibroblasts were infected with RV-2 or RV-16, or treated with RV-16 RNA, imiquimod (Toll-like receptor (TLR) 7/8 agonist) or polyinosinic : polycytidylic acid (poly I : C) (activator of TLR 3, retinoic-acid-inducible protein I and melanoma-differentiated-associated gene 5). Changes in ECM proteins and their transcription were measured by ELISA and quantitative real-time PCR. In addition, gene expression for ECM proteins was assessed in a mouse model of RV infection.

RESULTS

RV infection increased deposition of the ECM protein, perlecan, by human bronchial epithelial cells, and collagen V and matrix-bound vascular endothelial growth factor were increased in both human bronchial epithelial cell and fibroblast cultures. Purified RV-16 RNA, poly I : C and imiquimod induced similar increases in ECM deposition to those observed with RV-infected fibroblasts. However, only poly I : C induced ECM deposition by bronchial epithelial cells, suggesting that RV-induced ECM deposition is mediated through TLR. Furthermore, gene expression for fibronectin and collagen I was increased in lung homogenates of mice infected with RV-1b.

CONCLUSIONS

RV infection and TLR ligands promote ECM deposition in isolated cell systems and RV induces ECM gene expression in vivo, thus demonstrating that RV has the potential to contribute to remodelling of the airways through induction of ECM deposition.

Immunomodulatory activity of shikimic acid and quercitin in comparison with oseltamivir (Tamiflu) in an in vitro model

The risk of an avian influenza pandemic has put oseltamivir (Tamiflu) in the spotlight and has given rise to rumors that shikimic acid (SK), which is used for the synthesis of Tamiflu, possesses therapeutic activity. This study was undertaken to determine whether SK, either alone or in combination with quercitin (QT) is able to modulate the release of IL-6 and IL-8 from peripheral blood mononuclear cells (PBMCs). The experiments were conducted comparing the properties of SK, both alone and in combination, with those of Tamiflu. The incubation of PBMCs with 100 nM Tamiflu or SK at two concentrations (10 nM; 100 nM) did not produce any change in IL-6 and IL-8 baseline levels (data expressed as incremental change vs. baseline). On the contrary, incubation with SK and QT at both concentrations (10 and 100 nM) produced a significant increase in the release of IL-8 as compared to other groups (4.19 +/- 0.82, SK-QT 10 nM; 3.83 +/- 1.17 SK-QT 100 nM, P < 0.05 vs. baseline 1.00 +/- 0.10, Tamiflu 100 nM 1.35 +/- 0.16, SK 10 nM 1.68 +/- 0.15 and SK 100 nM 1.80 +/- 0.48). The SK-QT combination also proved to be effective in the upregulation of IL-6 (3.08 +/- 0.46, SK-QT 10 nM; 3.60 +/- 0.74 SK-QT 100 nM, P < 0.05 vs. baseline 1.00 +/- 0.26). According to these findings SK alone is not able to modulate innate immunity in antiviral terms. However, the data show that the SK + QT combination, even at low doses, may be effective for the modulation of innate immunity.

Bacterial extracts for the prevention of acute exacerbations in chronic obstructive pulmonary disease: a point of view

Given the high prevalence of chronic obstructive pulmonary disease (COPD), the impact of exacerbations on quality of life, and the costs incurred, effective ways for the prevention of exacerbations, and for reductions in the severity and duration of COPD symptoms are needed. Bacterial immunostimulation has been advocated as a management strategy in COPD for the purposes of preventing acute exacerbations. In particular, it suggests that the use of oral multicomponent vaccines may reduce the severity and duration of acute episodes. The way in which bacterial extracts may exert their effects is not fully understood although a number of possible specific mechanisms have been suggested. Given the high prevalence of COPD worldwide and the high cost of acute exacerbations, some cost-effectiveness analyses suggest that bacterial immunostimulants may become a key element in the improved control of this condition. Nonetheless, larger and longer clinical trials are needed to investigate efficacy before oral vaccination could be recommended as part of the routine clinical management of COPD, mainly in advanced COPD. It remains also to be investigated whether this protective effect may be additive to the other treatments. In any case, it is well known that for Streptococcus pneumoniae, non-typable Haemophilus influenzae and Moraxella catarrhalis, recurrent infections occur because of strain heterogeneity. Therefore, a single or even multiple strain vaccine with a killed whole cell formulation is possibly not the ideal vaccine. Moreover, the method of inactivation can affect the immunogenicity of essential antigens through denaturation. For this reason, the efficacy of bacterial immunostimulants should not only be assessed but also compared.

Clinical efficacy of OM-85 BV in COPD and chronic bronchitis: a systematic review

OM-85 BV is an immunomodulatory agent used for prevention of exacerbations in persons with chronic lung disease. We conducted a systematic review of OM-85 BV to evaluate its efficacy and safety. A systematic search for relevant articles was performed. Studies were included if they involved persons with chronic obstructive pulmonary disease or chronic bronchitis and were randomized to OM-85 BV or placebo. Investigators extracted data on study design, participant characteristics, and clinical outcomes. Thirteen trials involving 2066 individuals met inclusion criteria. Three trials enrolled an older, more homogenous population with chronic obstructive pulmonary disease. Utilizing quantitative pooled analysis in these studies, with one or more acute exacerbations as the endpoint, we found a non-statistically significant trend in favor of OM-85 BV [relative risk 0.83, 95% confidence interval 0.65-1.05]. Ten trials enrolled a heterogeneous population with chronic bronchitis. In these trials, exacerbation rates were less with OM-85 BV in 4 of 9 trials reporting this outcome. Varied results in the outcomes of hospitalization, symptom scores, and antibiotic or steroid use were found across studies. Withdrawals and adverse events were similar between OM-85 BV and placebo. While OM-85 BV is used to prevent exacerbations in persons with chronic lung disease, consistent evidence across multiple important outcomes does not exist to clearly demonstrate clinical benefit. Further randomized controlled trials enrolling large numbers of persons with well-defined COPD are necessary to confirm the effectiveness of this agent.

Oral bacterial vaccines for the prevention of acute exacerbations in chronic obstructive pulmonary disease and chronic bronchitis

Oral vaccines using killed bacterial extracts have been used to prevent acute exacerbations of chronic obstructive pulmonary disease (COPD); however, they are not recommended by current clinical guidelines. Two systematic reviews have been published on the efficacy of oral vaccines. The first, on the effects of an oral whole-cell nontypeable Haemophilus influenzae vaccine (NTHi) found a significant decrease in the incidence of acute episodes of chronic bronchitis (Poisson rate ratio 0.666; 95% confidence interval (CI) 0.500, 0.887; P = 0.005), and a 58% reduction in the prescription of antibiotics 3 months after vaccination. The second review evaluated studies that used multicomponent vaccines. It found that the duration of exacerbations was significantly shorter in the treatment group (weighted mean difference -2.7 days, 95% CI -3.5 to -1.8). These reviews suggest that oral vaccines reduce the number, severity, duration, or both, of acute exacerbations. However, many of the primary trials on which they are based are small and methodologically flawed. Further trials are needed before the use of oral vaccines could be considered as part of the routine clinical management of patients with COPD or chronic bronchitis.

Effect of IL-6 trans-signaling on the pro-remodeling phenotype of airway smooth muscle

Increased levels of IL-6 are documented in asthma, but its contribution to the pathology is unknown. Asthma is characterized by airway wall thickening due to increased extracellular matrix deposition, inflammation, angiogenesis, and airway smooth muscle (ASM) mass. IL-6 binds to a specific membrane-bound receptor, IL-6 receptor-alpha (mIL-6Ralpha), and subsequently to the signaling protein gp130. Alternatively, IL-6 can bind to soluble IL-6 recpetor-alpha (sIL-6Ralpha) to stimulate membrane receptor-deficient cells, a process called trans-signaling. We discovered that primary human ASM cells do not express mIL-6Ralpha and, therefore, investigated the effect of IL-6 trans-signaling on the pro-remodeling phenotype of ASM. ASM required sIL-6Ralpha to activate signal transducer and activator 3, with no differences observed between cells from asthmatic subjects compared with controls. Further analysis revealed that IL-6 alone or with sIL-6Ralpha did not induce release of matrix-stimulating factors (including connective tissue growth factor, fibronectin, or integrins) and had no effect on mast cell adhesion to ASM or ASM proliferation. However, in the presence of sIL-6Ralpha, IL-6 increased eotaxin and VEGF release and may thereby contribute to local inflammation and vessel expansion in airway walls of asthmatic subjects. As levels of sIL-6Ralpha are increased in asthma, this demonstration of IL-6 trans-signaling in ASM has relevance to the development of airway remodeling.

Use of OM-85 BV in children suffering from recurrent respiratory tract infections and subnormal IgG subclass levels

BACKGROUND

Recurrent acute respiratory tract infections (RARTIs) in children are related to IgG subclass deficiencies. The aim of the trial was to evaluate the effect of OM-85 BV in the number of RARTIs as well as in the IgG subclass levels.

METHODS

This was a randomized, double-blind, placebo-controlled clinical trial. Patients of ages three to six years, having three or more documented ARTIs during the last six months with subnormal IgG subclass levels were included. Patients took either one capsule of OM-85 BV (3.5 mg) or placebo orally every day for ten consecutive days per month during three consecutive months. Patients were followed three further months without drug intake. IgG subclass levels were determined before and after treatment.

RESULTS

IgG4 levels diminished after the OM-85 BV treatment (-3 [-8.0, -1.0] median difference [95 % CI] p < 0.05 by Wilcoxon test). No other significant changes in IgG subclasses were observed. After six months the patients in the OM-85 BV group (n = 20) experienced 2.8 1.4 (mean SD) ARTIs, while the patients in the placebo group (n = 20) suffered 5.2 1.5 ARTIs (-2.4 [3.3, -1.5] mean difference [95 % CI] p < 0.001 by Student's t test). Three patients with OM-85 BV had gastrointestinal events related to drug administration, as well as three placebo patients.

CONCLUSION

This study demonstrated the clinical benefit of OM-85 BV in patients suffering from RARTIs and subnormal levels of IgG subclasses. This trial opens new perspectives in the research of the mechanism of action of OM-85 BV.