Promising Immunomodulatory Effects of Bacterial Lysates in Allergic Diseases

A critical analysis of the effect of OM-85 for the prevention of recurrent respiratory tract infections or wheezing/asthma from systematic reviews with meta-analysis

Acute respiratory tract infections (RTIs) are one of the most common causes of pediatric consultations/hospitalizations and a major trigger for asthma exacerbations. Some consensus statements have recommended the use of immunostimulants to boost natural defenses against severe or repeated infections. One of the most common immunostimulants is OM-85; while several randomized clinical trials (RCTs) have evaluated its efficacy in preventing acute RTIs and wheezing/asthma exacerbations, results have been conflicting. Similarly, various systematic reviews with meta-analyses (SRMs) on OM-85 have used different strategies, populations, and outcomes; moreover, SRM conclusions are limited when the original studies are highly heterogeneous or have a low quality, hindering the generalizability of the findings. Here we summarize the evidence on the effect of OM-85 to prevent acute RTIs, wheezing/asthma episodes, or loss of asthma control in children, by including and critically evaluating all SRMs published to date. We searched for SRMs on OM-85 in three publication databases and found nine SRMs (seven for RTI, and two for wheezing/asthma). Among those, one had a high confidence evaluation of quality (AMSTAR-2 tool) and found a reduction in the total number of acute RTIs among the OM-85 group. Overall, no strong recommendations can be derived from the existing literature, mainly due to the high heterogeneity among included RCTs and SRMs. Further, large, high-quality RCTs are needed to confirm the true efficacy of OM-85 for the prevention of acute RTIs, asthma development, and asthma exacerbations.

Prevention of IgE-Mediated Food Allergy: Emerging Strategies Through Maternal and Neonatal Interventions

Whereas the early introduction of highly allergenic foods has been shown to be effective at preventing the onset of food allergy (FA) in high-risk infants, sensitization to food antigens can occur prior to complementary food introduction, and thus, additional earlier FA prevention strategies are urgently needed. Currently, aside from early introduction of peanut and egg, no therapies are strongly recommended by international professional allergy societies for the primary prevention of FA. This review focuses on maternal- and neonatal-directed interventions that are being actively investigated and developed, including maternal dietary factors and supplementation, specific elimination diets, breastfeeding, cow's milk formula supplementation, microbiome manipulations, bacterial lysate therapy, and skin barrier therapies. Evaluating how these factors and various prenatal/early life environmental exposures may impact the development of FA is crucial for accurately counseling caregivers in the prevention of FA.

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.

A quantitative systems pharmacology workflow toward optimal design and biomarker stratification of atopic dermatitis clinical trials

BACKGROUND

The development of atopic dermatitis (AD) drugs is challenged by many disease phenotypes and trial design options, which are hard to explore experimentally.

OBJECTIVE

We aimed to optimize AD trial design using simulations.

METHODS

We constructed a quantitative systems pharmacology model of AD and standard of care (SoC) treatments and generated a phenotypically diverse virtual population whose parameter distribution was derived from known relationships between AD biomarkers and disease severity and calibrated using disease severity evolution under SoC regimens.

RESULTS

We applied this workflow to the immunomodulator OM-85, currently being investigated for its potential use in AD, and calibrated the investigational treatment model with the efficacy profile of an existing trial (thereby enriching it with plausible marker levels and dynamics). We assessed the sensitivity of trial outcomes to trial protocol and found that for this particular example the choice of end point is more important than the choice of dosing regimen and patient selection by model-based responder enrichment could increase the expected effect size. A global sensitivity analysis revealed that only a limited subset of baseline biomarkers is needed to predict the drug response of the full virtual population.

CONCLUSIONS

This AD quantitative systems pharmacology workflow built around knowledge of marker-severity relationships as well as SoC efficacy can be tailored to specific development cases to optimize several trial protocol parameters and biomarker stratification and therefore has promise to become a powerful model-informed AD drug development and personalized medicine tool.

Characteristics of Lactococcus petauri GB97 lysate isolated from porcine feces and its in vitro and in vivo effects on inflammation, intestinal barrier function, and gut microbiota composition in mice

IMPORTANCE

Weaning is a crucial step in piglet management to improve pork production. During the weaning phase, disruption of epithelial barrier function and intestinal inflammation can lead to decreased absorption of nutrients and diarrhea. Therefore, maintaining a healthy intestine, epithelial barrier function, and gut microbiota composition in this crucial phase is strategic for optimal weaning in pigs. We isolated a lysate of Lactococcus petauri GB97 (LPL97) from healthy porcine feces and evaluated its anti-inflammatory activities, barrier integrity, and gut microbial changes in LPS-induced murine macrophages and DSS-induced colitis mice. We found that LPL97 regulated the immune response by downregulating the TLR4/NF-κB/MAPK signaling pathway both in vitro and in vivo. Furthermore, LPL97 alleviated the disruption of intestinal epithelial integrity and gut microbiota dysbiosis in colitis mice. This study indicates that LPL97 has the potential to be developed as an alternative feed additive to antibiotics for the swine industry.

Frequently asked questions about the ISAPP postbiotic definition

The term postbiotic was defined by the International Scientific Association of Probiotics and Prebiotics (ISAPP) as "a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host." Although the ISAPP definition is widely cited, some concerns were aired after publication, and alternative definitions of postbiotic, as well as different terms for inactivated microbes, have been previously suggested. This paper addresses questions about the ISAPP definition that have been raised in different forums, including scientific meetings, social media commentary and personal communications. We focus on the rationale, scope, wording, composition and commercial implementation, as well as what is expected of postbiotics regarding safety, efficacy, quantification and mechanisms of action. We hope that exploring these questions will further clarify the definition and its scope and support a common understanding of the concept of postbiotics.

Broncho-Vaxom bacterial lysate prevents asthma via acetate enhancement in mouse model

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Disturbed microbiota-metabolites-immune interaction network is associated with olfactory dysfunction in patients with chronic rhinosinusitis

Purpose

Olfactory dysfunction (OD) is a debilitating symptom frequently reported by patients with chronic rhinosinusitis (CRS) and it is associated with a dysregulated sinonasal inflammation. However, little information is available about the effect of the inflammation-related nasal microbiota and related metabolites on the olfactory function in these patients. Therefore, the current study aimed to investigate the nasal microbiota-metabolites-immune interactions and their role in the pathogenesis of OD in CRS patients.

Methods

23 and 19 CRS patients with and without OD, respectively, were enrolled in the present study. The "Sniffin' Sticks" was used to measure the olfactory function, while the metagenomic shotgun sequencing and the untargeted metabolite profiling were performed to assess the differences in terms of the nasal microbiome and metabolome between the two groups. The levels of nasal mucus inflammatory mediators were investigated by a multiplex flow Cytometric Bead Array (CBA).

Results

A decreased diversity in the nasal microbiome from the OD group compared to the NOD group was evidenced. The metagenomic analysis revealed a significant enrichment of Acinetobacter johnsonii in the OD group, while Mycoplasma arginini, Aeromonas dhakensis, and Salmonella enterica were significantly less represented (LDA value > 3, p < 0.05). The nasal metabolome profiles were significantly different between the OD and NOD groups (P < 0.05). The purine metabolism was the most significantly enriched metabolic subpathway in OD patients compared with NOD patients (P < 0.001). The expressions of IL-5, IL-8, MIP-1α, MCP-1, and TNF were statistically and significantly increased in the OD group (P < 0.05). All these data, including the dysregulation of the nasal microbiota, differential metabolites, and elevated inflammatory mediators in OD patients demonstrated a clear interaction relationship.

Conclusion

The disturbed nasal microbiota-metabolite-immune interaction networks may be implicated in the pathogenesis of OD in CRS patients and the underlying pathophysiological mechanisms need to be further investigated in future studies.

E. coli Phagelysate: A Primer to Enhance Nanoparticles and Drug Deliveries in Tumor

The tumor microenvironment (TME), where cancer cells reside, plays a crucial role in cancer progression and metastasis. It maintains an immunosuppressive state in many tumors and regulates the differentiation of precursor monocytes into M1 (anti-tumor)- and M2 (pro-tumor)-polarized macrophages, and greatly reduces anticancer drug and nanoparticle delivery. As a result, the effectiveness of recently developed chemo- and/or nanotechnology-mediated immune and magnetic nanoparticle hyperthermia (mNPH) therapies is inhibited significantly. One of the ways to overcome this limitation is to use E. coli phagelysate as a primer to modify the tumor microenvironment by switching tumor-associated M2 macrophages to anti-tumor M1 macrophages, and initiate the infiltration of tumor-associated macrophages (TAMs). Recently, bacteriophages and phage-induced lysed bacteria (bacterial phagelysates-BPLs) have been shown to be capable of modifying the tumor-associated environment. Phage/BPL-coated proteins tend to elicit strong anti-tumor responses from the innate immune system, prompting phagocytosis and cytokine release. It has also been reported that the microenvironments of bacteriophage- and BPL-treated tumors facilitate the conversion of M2-polarized TAMS to a more M1-polarized (tumoricidal) environment post-phage treatment. This paper demonstrates the feasibility and enhanced efficacy of combining E. coli phagelysate (EcPHL) and mNPH, a promising technology for treating cancers, in a rodent model. Specifically, we illustrate the EcPHL vaccination effect on the TME and mNP distribution in Ehrlich adenocarcinoma tumors by providing the tumor growth dynamics and histology (H&E and Prussian blue) distribution of mNP in tumor and normal tissue.

Serum antibodies to periodontal pathogens are related to allergic symptoms

BACKGROUND

The association between periodontitis and allergic symptoms has been investigated. However, the difference in immune signatures between them remains poorly understood. This cross-sectional study assessed the relationship between serum immunoglobulin G (IgG) antibodies to periodontal pathogens and allergic symptoms in a nationwide population cohort.

METHODS

Two phases of the Third National Health and Nutrition Examination Survey (NHANES III) were used as discovery dataset (n = 3700) and validation dataset (n = 4453), respectively. Based on the antibodies against 19 periodontal pathogens, we performed an unsupervised hierarchical clustering to categorize the population into three clusters. In the discovery dataset, cluster 1 (n = 2847) had the highest level of IgG antibodies, followed by clusters 2 (n = 588) and 3 (n = 265). Data on allergic symptoms (asthma, hay fever, and wheezing) were obtained using a self-reported questionnaire. Survey-weighted multivariable logistic regression evaluated the association between these clusters and allergic symptoms.

RESULTS

In the discovery dataset, the participants with lower levels of antibodies to periodontal pathogens exhibited a higher risk of asthma (odds ratio [OR]_{cluster 3 vs. cluster 1} = 1.820, 95% confidence interval [CI]: 1.153-2.873) and wheezing (OR_{cluster 3 vs. cluster 1} = 1.550, 95% CI: 1.095-2.194) compared to those with higher periodontal antibodies, but the non-significant association with hay fever. Consistent results were found in the validation dataset.

CONCLUSIONS

Serum IgG titers to periodontal pathogens were inversely associated with the risk of asthma and wheezing, suggesting the potentially protective role against allergic conditions.

Effect of immunostimulation with bacterial lysate on the clinical course of allergic rhinitis and the level of γδT, iNKT and cytotoxic T cells in children sensitized to grass pollen allergens: A randomized controlled trial

Background

There are many drugs for allergic rhinitis (AR), however, these drugs show variable clinical effectiveness and some side effects. Therefore, new methods of AR pharmacotherapy are being sought.

Objectives

The objectives of this study were to evaluate the efficacy of polyvalent mechanical bacterial lysate (PMBL) therapy in improving the clinical course of grass pollen-induced AR (seasonal AR, SAR) in children and its effect on changes in the blood level of the γδT, iNKT and cytotoxic T cell subsets.

Methods

Fifty children with SAR were enrolled in this study and were randomly assigned to either the PMBL group or the placebo group. The severity of SAR symptoms was assessed using the total nasal symptom score (TNSS) and visual analogue scale (VAS). During two visits (V1, V2), peak nasal inspiratory flow (PNIF) was measured and peripheral blood was collected for immunological analyses. The study also included 2 telephone contacts (TC1, TC2).

Results

The severity of the nasal symptoms of SAR on the TNSS scale was revealed to have a significantly lower impact in the PMBL group vs the placebo group at measuring points TC1 and V2 (p = 0.01, p = 0.009, respectively). A statistically significantly lower mean severity of nasal symptoms of SAR on the VAS scale was recorded for children in the PMBL group compared to the placebo group at measuring points TC1, V2 and TC2 (p = 0.04, p = 0.04, p = 0.03, respectively). The compared groups do not show significant differences in terms of PNIF values at individual measuring points. There were no statistically significant changes in immune variables. For both groups, there was a statistically significant association between the level of Th1-like γδT cells and the severity of SAR symptoms expressed on the TNSS scale (p = 0.03) - the lower the level of Th1-like γδT cells, the higher the TNSS value.

Conclusion

Administration of sublingual PMBL tablets during the grass pollen season proves to have a high efficacy in alleviating SAR symptoms in children sensitized to grass pollen allergens. Th1-like γδT cells may be used as potential markers for SAR severity in children.

Clinical trial registration

ClinicalTrials.gov, identifier (NCT04802616).

Molecular Mechanisms of Luteolin Against Atopic Dermatitis Based on Network Pharmacology and in vivo Experimental Validation

PURPOSE

To undercover the underlying mechanisms of luteolin against atopic dermatitis (AD), clinically characterized by recurrent eczematous lesions and intense itching, based on network pharmacology, molecular docking and in vivo experimental validation.

METHODS

TCMSP, STITCH and SwissTargetPrediction databases were utilized to screen the corresponding targets of luteolin. Targets related to AD were collected from DisGeNET, GeneCards and TTD databases. PPI network of intersection targets was constructed through STRING 11.0 database and Cytoscape 3.9.0 software. GO and KEGG enrichment analysis were performed to investigate the critical pathways of luteolin against AD. Further, the therapeutic effects and candidate targets/signaling pathways predicted from network pharmacology analysis were experimentally validated in a mouse model of AD induced by 2, 4-dinitrofluorobenzene (DNFB).

RESULTS

A total of 31 intersection targets were obtained by matching 151 targets of luteolin with 553 targets of AD. Among all, 20 core targets were identified by PPI network topology analysis, including IL-6, TNF, IL-10, VEGFA, IL-4, etc., and molecular docking indicated that luteolin binds strongly to these core targets. KEGG pathway enrichment analysis suggested that the intersected targets were significantly enriched in IL-17 signaling pathway, Th17 cell differentiation, Th1 and Th2 cell differentiation, JAK/STAT signaling pathway, etc. The in vivo experiment validated that luteolin could alleviate AD-like skin symptoms, as evidenced by the lower SCORAD score, the reduced infiltration of mast cells and the recovery of skin barrier function. Furthermore, luteolin restored immune balance by regulating the production of Th1/Th2/Th17-mediated cytokines, which were both the predicted core targets. Moreover, luteolin inhibited the phosphorylation of JAK2 and STAT3 in the lesional skin.

CONCLUSION

Together, the present study systematically clarifies the ameliorative effects and possible molecular mechanisms of luteolin against AD through the combination of network pharmacology and experimental validation, shedding light on the future development and clinical application of luteolin.

The Crosstalk between the Gut Microbiota Composition and the Clinical Course of Allergic Rhinitis: The Use of Probiotics, Prebiotics and Bacterial Lysates in the Treatment of Allergic Rhinitis

Although massive progress in discovering allergic rhinitis (AR) aetiology has been made in recent years, its prevalence is still rising and it significantly impacts patients' lives. That is why further and non-conventional research elucidating the role of new factors in AR pathogenesis is needed, facilitating discoveries of new treatment approaches. One of these factors is the gut microbiota, with its specific roles in health and disease. This review presents the process of gut microbiota development, especially in early life, focusing on its impact on the immune system. It emphasizes the link between the gut microbiota composition and immune changes involved in AR development. Specifically, it elucidates the significant link between bacteria colonizing the gut and the Th1/Th2 imbalance. Probiotics, prebiotics and bacterial lysates, which are medications that restore the composition of intestinal bacteria and indirectly affect the clinical course of AR, are also discussed.

Respiratory syncytial virus, recurrent wheeze and asthma: A narrative review of pathophysiology, prevention and future directions

Globally, respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in young children, and the association between severe RSV disease and later recurrent wheeze and asthma is well established. Whilst a causal link between RSV and wheeze/asthma is not yet proven, immunological evidence suggests skewing towards a Th2-type response, and dampening of IFN-γ antiviral immunity during RSV infection underpins airway hyper-reactivity in a subset of susceptible children after RSV infection. Age at primary RSV infection, viral co-infection and genetic influences may act as effect-modifiers. Despite the significant morbidity and mortality burden of RSV disease in children, there is currently no licensed vaccine. Recent advancements in RSV preventatives, including long-acting monoclonal antibodies and maternal vaccinations, show significant promise and we are on the cusp of a new era in RSV prevention. However, the potential impact of RSV preventatives on subsequent wheeze and asthma remains unclear. The ongoing COVID-19 pandemic and associated public health measures have disrupted the usual seasonality of RSV. Whilst this has posed challenges for health-care services it has also enhanced our understanding of RSV transmission. The near absence of RSV cases during the first year of the pandemic in the context of strict public health measures has provided a rare opportunity to study the impact of delayed age of primary RSV infection on asthma prevalence. In this review, we summarise current understanding of the association between RSV, recurrent wheeze and asthma with a focus on pathophysiology, preventative strategies and future research priorities.

Anti-allergic function of the cell wall (DeinoWall) from Deinococcus radiodurans

Deinococcus radiodurans is an extremophile, well known to be extremely resistant to external stresses due to its unique physiological system and structure of cellular components. Although the proportion of D. radiodurans has been reported to be negatively correlated with atopic dermatitis, the exact function of D. radiodurans in allergic diseases and its precise mechanisms have not been studied. In the present study, we hypothesize that D. radiodurans or its cellular constituents play a critical role in the skin to prevent allergic inflammatory responses by modulating immunity. Heat-killed D. radiodurans inhibited the production of Th2 cytokines, such as IL-4 and IL-5, induced by ovalbumin (OVA) stimulation in splenocytes from OVA-sensitized mice. Among the cellular constituents of D. radiodurans, such as cell wall (DeinoWall), cell membrane (DeinoMem), and exopolysaccharide (DeinoPol), only DeinoWall inhibited the production of Th2 cytokines and 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD), a Th2-predominant allergic disease in mice. Moreover, serum IgE levels and infiltration of mast cells into skin lesions, the markers of Th2 response induced by DNCB application, were significantly inhibited by treatment with DeinoWall. Remarkably, DeinoWall induced the maturation of bone marrow-derived dendritic cells (BMDCs) that promote Th1-biased immunity, which might balance Th1/Th2 and regulate allergic inflammatory responses. Collectively, these results suggest that DeinoWall acts as a major cellular constituent in the negative regulation of allergic inflammatory responses by D. radiodurans and might be a viable candidate for the treatment of allergic diseases.