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Vaccination is the most effective way to confer potent and long-term protection from infectious diseases. However, poorer responses to immunization are common in young adults with sub-optimal immune health and the elderly because of immunosenescence and increased comorbidities. Recent mechanistic studies have highlighted that the microbiota and its compounds modulate many molecular pathways that can influence the host immune system. Consequently, altering the microbiota composition or ac-tivity with immunonutrition, specifically with biotic interventions (probiotics, prebiotics, synbiotics, or postbiotics), may enhance the immune response and vaccine efficacy. This review aims to examine the available data for these biotic strategies to provide clinicians, researchers, and vaccine developers with a mechanistically driven synthesis of how biotic interventions could modulate the immune responses to vaccination. The article describes some postulated mechanistic pathways involved in immunological responses to vaccines and immunomodulation with biotic interventions. Randomized clinical trials were also reviewed to evaluate the impact of specific biotic interventions on vaccination outcomes in different age groups. Few strains and formulations significantly increased antigen-specific antibody titers in in-dividual of all ages. However, studies have also pointed to a substantial heterogeneity that can be attributed to the difference in biotic intervention, strain, dose, viability, type of vaccine antigen, study location, as well as duration, and timing of administration. Future investigations should focus on establishing optimal strains, doses, and timing of administration with respect to vaccination, especially in the elderly and children, where vaccine effectiveness and duration of immunization matter.(c) 2023 Published by Elsevier Ltd.

Beneficial bacteria represent an emerging tool against topical diseases, including infection caused by Staphylococcus aureus. Here, we investigated several anti-pathogenic mechanisms of the model probiotic Lacticaseibacillus rhamnosus GG against a clinical S. aureus isolate by implementing various mutants lacking important cell surface molecules. We analysed adhesion of L. rhamnosus and competitive adhesion with S. aureus to primary human keratinocytes, L. rhamnosus and S. aureus auto- and co-aggregation, S. aureus growth inhibition, keratinocyte viability increase, and monocyte Toll-like receptor (TLR) activation by L. rhamnosus as such, or with S. aureus. L. rhamnosus mutated in SpaCBA pili exhibited reduced adhesion to keratinocytes, reduced ability to prevent S. aureus adhesion to keratinocytes and reduced co-aggregation with S. aureus. Mutants in cell wall exopolysaccharides showed enhanced adhesion to keratinocytes and TLR activation in monocytes, suggesting involvement of additional cell surface molecules masked by exopolysaccharides. All L. rhamnosus strains inhibited S. aureus growth, likely due to acidification of the medium. Live (but not UV-inactivated) L. rhamnosus significantly reduced inflammatory TLR activation in monocytes by S. aureus. These data suggest the key role of SpaCBA pili and additional contribution of other cell surface molecules as well as secreted components of L. rhamnosus GG in the multifactorial inhibition of S. aureus adhesion and toxicity in the skin niche.

Riboflavin-producing lactic acid bacteria represent a promising and cost-effective strategy for food biofortification, but production levels are typically insufficient to support daily human requirements. In this study, we describe the novel human isolate

The vaginal microbiome is crucial for women’s health and reproduction, but its ecology and determinants in the general population are still unclear. This lack of a reference framework hampers much-needed innovations in diagnostics and therapeutics. Here, we remotely mapped the vaginal microbiome of 3,345 women in Western Europe via a citizen-science approach. More than 75% of the vaginal samples were dominated by Lactobacillus taxa, but not in discrete community state types. Compositional correlation network analysis validated with public data pointed at six main modules of interacting microbes: a Lactobacillus crispatus-, Lactobacillus iners-, Gardnerella-, Prevotella-, Anaerococcus-, and gut-derived module. In the first module, Limosilactobacillus taxa were functionally connected to L. crispatus and Lactobacillus jensenii. This module was positively associated with the luteal phase of the menstrual cycle and negatively with the number of vaginal complaints, while the Gardnerella-module was associated with discharge and increasing age. Contraceptives with oestrogen correlated with higher levels of the L. crispatus- and less of the Gardnerella-module, with the opposite found for a hormonal intrauterine device or having multiple partners. Mothers had lower relative abundance of the L. crispatus-module and more Bifidobacterium, Lactobacillus gasseri and Streptococcus. Other covariates such as BMI, menstrual pads and cups, smoking and dietary habits were also associated with the microbial constellation. These findings suggest that lifestyle interventions have potential to improve vaginal health when combined with dedicated therapies.

Respiratory viruses such as influenza viruses, respiratory syncytial virus (RSV), and coronaviruses initiate infection at the mucosal surfaces of the upper respiratory tract (URT), where the resident respiratory microbiome has an important gatekeeper function. In contrast to gut-targeting administration of beneficial bacteria against respiratory viral disease, topical URT administration of probiotics is currently underexplored, especially for the prevention and/or treatment of viral infections. Here, we report the selection and formulation of a broad-acting throat spray with live lactobacilli which induce interferon regulatory pathways and are able to inhibit respiratory viruses. Rational selection of Lactobacillaceae strains was based on safety, applicability, and potential antiviral and immunostimulatory efficacy in the URT. Three strains, Lacticaseibacillus casei AMBR2, Lacticaseibacillus rhamnosus GG and Lactiplantibacillus plantarum WCFS1 significantly reduced the cytopathogenic effects of RSV, influenza A/H1N1 and B viruses, and HCoV-229E coronavirus in co-culture models with bacteria, virus and host cells. Subsequently, these strains were formulated in a throat spray and human monocytes were employed to confirm the formulation process did not reduce the interferon regulatory pathway-inducing capacity. Administration of the throat spray in healthy volunteers revealed that the lactobacilli were capable of temporary colonization of the throat in a metabolically active form.

Tailored skin microbiome modulation approaches with probiotics are highly challenging. Here, we show that lactobacilli are underestimated members of the skin microbiota. We select specific strains of nomadic lactobacilli for their functional applicability on the skin and capacity to inhibit growth and inflammation by skin pathobionts. The strains are formulated as microcapsules for topical formulations and tested in patients with mild-to-moderate acne. The selected lactobacilli are able to reduce inflammatory lesions in a pilot and placebo-controlled study. Daily application for 8 weeks is associated with an in vivo temporary modulation of the microbiome, including a reduction in relative abundance of staphylococci and Cutibacterium acnes, and an increase in lactobacilli. The reduction in inflammatory lesions is still apparent 4 weeks after the topical application of the lactobacilli ended, indicating a possible additional immunomodulatory effect. This study shows that carefully selected and formulated lactobacilli are a viable therapeutic option for common acne lesions.

Summary Comparing the nasal microbiome of healthy individuals and chronic rhinosinusitis (CRS) patients revealed Dolosigranulum pigrum as a species clearly associated with nasal health, although isolates obtained from healthy individuals are scarce. In this study, we explored the properties of this understudied lactic acid bacterium by integrating comparative genomics, habitat mining, cultivation, and functional characterization of interaction capacities. Mining 10.000 samples from the Earth Microbiome Project of 17 habitat types revealed that Dolosigranulum is mainly associated with the human nasal cavity. D. pigrum AMBR11 isolated from the nose of a healthy individual exerted antimicrobial activity against Staphylococcus aureus, decreased proinflammatory cytokine production in airway epithelial cells, and Galleria mellonella larvae mortality induced by this important nasal pathobiont. Furthermore, the strain protected the nasal barrier function in a mouse model using interleukin-4 as disruptive cytokine. Hence, D. pigrum AMBR11 is a mutualist with high potential as topical live biotherapeutic product., Graphical abstract, Highlights • Habitat mining reveals that Dolosigranulum pigrum prefers the human nasal cavity • D. pigrum AMBR11 has immunomodulatory and nasal barrier-enhancing capacities • D. pigrum AMBR11 exerts antimicrobial activity against S. aureus, Immunology; Microbiology; Microbiome

Emerging evidence suggests that microbial therapeutics can prevent and treat respiratory viral diseases, especially when applied directly to the airways. This review presents established beneficial effects of locally administered microbial therapeutics against respiratory viral diseases and the inferred related molecular mechanisms. Several mechanisms established in the intestinal probiotics field as well as novel, niche-specific insights are relevant in the airways. Studies at cellular and organism levels highlight biologically plausible but strain-specific and host and virus context-dependent mechanisms, underlying the potential of beneficial bacteria. Large-scale clinical studies can now be rationally designed to provide a bench-to-bedside translation of the multifactorial bacterial mechanisms within the host respiratory tract, to diminish the incidence and severity of viral infections and the concomitant complications.

Comparing the nasal microbiome of healthy individuals and chronic rhinosinusitis (CRS) patients revealed Dolosigranulum pigrum as a species clearly associated with nasal health, although it was not yet cultured from healthy individuals. In this study, we explored the properties of this understudied lactic acid bacterium by integrating comparative genomics, habitat mining, cultivation, and functional characterization of interaction capacities. Mining 10.000 samples from the Earth Microbiome Project of 17 habitat types revealed that Dolosigranulum is mainly associated with the human nasal cavity. D. pigrum AMBR11 isolated from the nose of a healthy individual exerted antimicrobial activity against Staphylococcus aureus , and decreased proinflammatory cytokine production in airway epithelial cells and Galleria mellonella larvae mortality induced by this important nasal pathobiont. Furthermore, the strain protected the nasal barrier function in a mouse model using interleukin-4 as disruptive cytokine. Hence, D. pigrum AMBR11 is a mutualist with high potential as topical live-biotherapeutic product.

Comparing the nasal microbiome of healthy individuals and chronic rhinosinusitis (CRS) patients revealed Dolosigranulum pigrum as a species clearly associated with nasal health, although isolates obtained from healthy individuals are scarce. In this study, we explored the properties of this understudied lactic acid bacterium by integrating comparative genomics, habitat mining, cultivation, and functional characterization of interaction capacities. Mining 10.000 samples from the Earth Microbiome Project of 17 habitat types revealed that Dolosigranulum is mainly associated with the human nasal cavity. D. pigrum AMBR11 isolated from the nose of a healthy individual exerted antimicrobial activity against Staphylococcus aureus, decreased proinflammatory cytokine production in airway epithelial cells, and Galleria mellonella larvae mortality induced by this important nasal pathobiont. Furthermore, the strain protected the nasal barrier function in a mouse model using interleukin-4 as disruptive cytokine. Hence, D. pigrum AMBR11 is a mutualist with high potential as topical live biotherapeutic product. ispartof: ISCIENCE vol:24 issue:9 ispartof: location:United States status: published

During the current COVID-19 pandemic, the use of face masks has become increasingly recommended and even mandatory in community settings. To evaluate the risk of bacterial cross-contamination, this study analyzed the bacterial bioburden of disposable surgical masks and homemade cotton masks, and surveyed the habits and face mask preferences of the Flemish population. Using culture approaches and 16S rRNA gene amplicon sequencing, we analyzed the microbial community on surgical and/or cotton face masks of 13 healthy volunteers after 4 h of wearing. Cotton and surgical masks contained on average 1.46 × 105 CFU/mask and 1.32 × 104 CFU/mask, respectively. Bacillus, Staphylococcus, and Acinetobacter spp. were mostly cultured from the masks and 43% of these isolates were resistant to ampicillin or erythromycin. Microbial profiling demonstrated a consistent difference between mask types. Cotton masks mainly contained Roseomonas, Paracoccus, and Enhydrobacter taxa and surgical masks Streptococcus and Staphylococcus. After 4 h of mask wearing, the microbiome of the anterior nares and the cheek showed a trend toward an altered beta-diversity. According to dedicated questions in the large-scale Corona survey of the University of Antwerp with almost 25,000 participants, only 21% of responders reported to clean their cotton face mask daily. Laboratory results indicated that the best mask cleaning methods were boiling at 100°C, washing at 60°C with detergent or ironing with a steam iron. Taken together, this study suggests that a considerable number of bacteria, including pathobionts and antibiotic resistant bacteria, accumulate on surgical and even more on cotton face masks after use. Based on our results, face masks should be properly disposed of or sterilized after intensive use. Clear guidelines for the general population are crucial to reduce the bacteria-related biosafety risk of face masks, and measures such as physical distancing and increased ventilation should not be neglected when promoting face mask use.

Scope: Chlorogenic acid (5-caffeoylquinic acid), the most prominent polyphenolic compound in coffee, has been attributed multiple health-promoting effects such as anti-inflammatory, antidiabetic and antioxidative effects. These effects are dependent on the bioavailability of chlorogenic acid, which is determined by the pharmacokinetic properties: absorption, distribution, metabolism and excretion (ADME). In order to have a better understanding of the biological properties of chlorogenic acid and to optimize formulation and dosing of chlorogenic acid-containing food supplements, information on the absorption of chlorogenic acid and its microbial biotransformation products is of essence. Methods and results: In the present work, the intestinal absorption of chlorogenic acid and quinic acid, one of its most prominent intestinal biotransformation products, was studied by an in vitro permeability assay using a human Caco-2 cell line model. For both chlorogenic acid and quinic acid, the involvement of an active efflux mechanism was demonstrated, suggesting an overall low intestinal absorption. Conclusions: An overall low intestinal absorption for chlorogenic acid and quinic acid was reported given the involvement of an active efflux mechanism. These findings could aid in the development of optimal formulation and dosing strategies of chlorogenic acid in food supplements in order to obtain beneficial health effects.

The human skin microbiota forms a key barrier against skin pathogens and is important in modulating immune responses. Recent studies identify lactobacilli as endogenous inhabitants of healthy skin, while inflammatory skin conditions are often associated with a disturbed skin microbiome. Consequently, lactobacilli-based probiotics are explored as a novel treatment of inflammatory skin conditions through their topical skin application. This review focuses on the potential beneficial role of lactobacilli (family Lactobacillaceae) in the skin habitat, where they can exert multifactorial local mechanisms of action against pathogens and inflammation. On one hand, lactobacilli have been shown to directly compete with skin pathogens through adhesion inhibition, production of antimicrobial metabolites, and by influencing pathogen metabolism. The competitive anti-pathogenic action of lactobacilli has already been described mechanistically for common different skin pathogens, such as Staphylococcus aureus, Cutibacterium acnes, and Candida albicans. On the other hand, lactobacilli also have an immunomodulatory capacity associated with a reduction in excessive skin inflammation. Their influence on the immune system is mediated by bacterial metabolites and cell wall-associated or excreted microbe-associated molecular patterns (MAMPs). In addition, lactobacilli can also enhance the skin barrier function, which is often disrupted as a result of infection or in inflammatory skin diseases. Some clinical trials have already translated these mechanistic insights into beneficial clinical outcomes, showing that topically applied lactobacilli can temporarily colonize the skin and promote skin health, but more and larger clinical trials are required to generate in vivo mechanistic insights and in-depth skin microbiome analysis.

Probiotic bacteria are being explored for the in situ delivery of various therapeutic agents. In this study, we aimed to express two HIV-inhibiting lectins, actinohivin (AH) and griffithsin (GRFT), in the probiotic strains Lactobacillus rhamnosus GG and L. rhamnosus GR-1 for gastrointestinal and vaginal mucosal delivery, respectively. Constructs were generated for the intracellular and extracellular production of AH and GRFT under the control of the promoter of their Major Secreted Protein Msp1. Also, intracellular expression of GRFT was investigated under the control of the nisA promoter from the inducible nisin-controlled expression (NICE) system. For the extracellular localization, the signal leader peptide of Msp1/p75 from L. rhamnosus GG was translationally fused with the genes encoding AH and GRFT. Construction of recombinant strains expressing the AH monomer and dimer was unsuccessful, probably due to the intracellular toxicity of AH for the lactobacilli. On the other hand, recombinant strains for intra- and extracellular production of GRFT by L. rhamnosus GG and GR-1 were successfully constructed. The highest expression levels of recombinant GRFT were observed for the constructs under the control of the inducible nisA promoter and we demonstrated anti-HIV activity against an M-tropic and a T-tropic HIV-1 strain. We can conclude that recombinant Lactobacillus expressing anti-HIV lectins could contribute to the development of enhanced probiotic strains that are able to inhibit HIV transmission and subsequent replication, although further research and development are required. ispartof: INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS vol:52 issue:5 pages:599-607 ispartof: location:Netherlands status: published

Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefit on the host. The therapeutic effects of probiotics have been mostly studied in the gastrointestinal tract, but recent evidence points toward the potential of these bacteria to prevent and/or treat chronic airway diseases. In this review, possible mechanisms of action of probiotics in the airways are described, with a particular focus on their capacity to modulate the epithelial barrier function and their mode of interaction with the immune system. Indeed, probiotic bacteria, mostly lactobacilli, can promote the expression and regulation of tight junctions and adherence junctions, resulting in the restoration of a defective epithelial barrier. These bacteria interact with the epithelial barrier and immune cells through pattern recognition receptors, such as Toll-like receptors, which upon activation can stimulate or suppress various immune responses. Finally, the clinical potential of probiotics to treat inflammatory diseases of the upper and lower respiratory tract, and the difference between their mode of application (eg, oral or nasal) are discussed here. ispartof: ALLERGY vol:73 issue:10 pages:1954-1963 ispartof: location:Denmark status: published

Although an increasing number of beneficial microbiome members are characterized for the human gut and vagina, beneficial microbes are underexplored for the human upper respiratory tract (URT). In this study, we demonstrate that taxa from the beneficial Lactobacillus genus complex are more prevalent in the healthy URT than in patients with chronic rhinosinusitis (CRS). Several URT-specific isolates are cultured, characterized, and further explored for their genetic and functional properties related to adaptation to the URT. Catalase genes are found in the identified lactobacilli, which is a unique feature within this mostly facultative anaerobic genus. Moreover, one of our isolated strains, Lactobacillus casei AMBR2, contains fimbriae that enable strong adherence to URT epithelium, inhibit the growth and virulence of several URT pathogens, and successfully colonize nasal epithelium of healthy volunteers. This study thus demonstrates that specific lactobacilli are adapted to the URT and could have a beneficial keystone function in this habitat. De Boeck et al. show that lactobacilli are decreased in patients with chronic rhinosinusitis and enriched in healthy controls. They isolate one strain adapted to the nasopharyngeal mucosa that shows beneficial probiotic effects and safety in the form of a nasal spray in healthy volunteers.

The increasing prevalence of allergic airway diseases in industrialized countries has been associated with high hygienic standards and reduced microbial exposure. Probiotic lactic acid bacteria, such as certain Lactobacillus strains, were shown to have potentially beneficial immunomodulatory properties. Therefore, we determined the effect of intranasal administration of L. rhamnosus GG (LGG) and GR-1 (LGR-1) in a mouse model of birch pollen-induced allergic asthma. The symptoms of allergic asthma were induced with 7 intranasal applications with 1- or 2-day interval with birch pollen extract. The asthma induction protocol was preceded by 8 intranasal administrations of LGG or LGR-1 at a concentration of 5 x 108 CFU/dose over the course of two weeks on four consecutive days each week. We assessed serum antibody levels, bronchoalveolar lavage (BAL) cell counts, lung histology, lung cytokine levels, airway hyperreactivity. LGG administration resulted in a significant decrease in allergic airway inflammation (BAL eosinophils, lung IL-13 and IL-5 levels) and a significantly reduced number of respiratory exacerbations. Contrary to LGG, no decisive results were obtained for LGR-1. Longitudinal in vivo lung micro-computed tomography (micro-CT) is currently ongoing to determine inflammatory exacerbation. Complementary to micro-CT, fluorescence imaging (FLI) of a fluorescent LGG strain will be performed to understand the probiotic-host interactions at the whole-body and whole-organ level. In conclusion, bacterial strain-specific beneficial effects of intranasally administered LGG were observed in a mouse model of birch pollen-induced allergic asthma.

While an increasing number of beneficial microbiome members is characterized for the human gut and vagina, beneficial microbes are underexplored for the human upper respiratory tract (URT). In this study, we demonstrate that taxa from the beneficial Lactobacillus genus might have a role as keystone species in the healthy URT. Several URT-specific Lactobacillus isolates were cultured, characterized, and further explored for their genetic and functional properties related to adaptation to the URT. Catalase genes were found in the identified Lactobacillus taxa, which is a unique feature within this mostly facultative anaerobic genus. Moreover, one of our isolated strains, Lactobacillus casei AMBR2, contained unique fimbriae enabling strong adherence to URT epithelium, inhibited the growth and virulence of several URT pathogens, and successfully colonized nasal epithelium of healthy volunteers. This study thus demonstrates that specific Lactobacillus taxa are adapted to the URT and could have a beneficial keystone function in this habitat.

Background There is an increasing interest in targeted application of probiotic bacteria for prevention and treatment of airway diseases, including allergies. Here, we investigated the beneficial effects of preventive intranasal treatment with probiotics Lactobacillus rhamnosus GG and L. rhamnosus GR‐1 in a mouse model of allergic asthma. Methods Lactobacillus rhamnosus was administered intranasally eight times on days 1‐4 and 8‐11 at 5 × 108 CFU/dose, followed by a 2‐week asthma induction protocol with birch pollen extract on alternating days. Effects of preventive treatment were analyzed based on serum antibody levels, bronchoalveolar lavage cell counts, lung histology, lung cytokine levels, and airway hyperreactivity. Colonization and translocation of L. rhamnosus were assessed by bacterial cell counts in nasal mucosa, fecal samples, cervical lymph nodes, and blood. Binding of fluorescent L. rhamnosus to fixed murine nasal mucosal cells and airway macrophages was visualized by fluorescence microscopy. Results Transient colonization of the murine upper airways by L. rhamnosus GG was demonstrated and was approximately ten times higher compared to L. rhamnosus GR‐1. Marked binding of fluorescent L. rhamnosus GG to murine nasal mucosal cells and airway macrophages was visualized. Preventive treatment with L. rhamnosus GG (but not L. rhamnosus GR‐1) resulted in a significant decrease in bronchoalveolar lavage eosinophil counts, lung interleukin‐13 and interleukin‐5 levels, and airway hyperreactivity. A tendency toward a decrease in serum Bet v 1‐specific immunoglobulin G1 was likewise observed. Conclusion Intranasally administered L. rhamnosus GG prevents the development of cardinal features of birch pollen‐induced allergic asthma in a strain‐specific manner.

A meeting report on the 7th Wellcome Trust conference on Exploring Human Host-Microbiome Interactions in Health and Disease, held at Hinxton, UK, 5-7 December 2018.

SummaryThe skin is home to an important part of our commensal microbiota, despite it being a cool, acidic and desiccated environment. Tailored microbiome modulation approaches with, for example probiotics, are highly challenging for this body site. Here we show by next-generating sequencing that Lactobacillus taxa -especially those known to be dominant in the human vagina- are underestimated members of the skin microbiota. Specific Lactobacillus strains were selected in the lab and formulated in a viable form in an oil in water-based topical cream. Facial application by patients with mild-to-moderate acne symptoms was able to reduce inflammatory lesions and comedone formation. This was associated with a temporary modulation of the skin microbiome, including a reduction in relative abundance of staphylococci and an increase in lactobacilli. Skin microbiome modulation by addition of carefully formulated lactobacilli seems to be new therapeutic option to reduce antibiotic use for common acne symptoms.

The worldwide prevalence of allergic diseases has drastically increased in the past decades. Recent studies underline the importance of microbial exposure for the development of a balanced immune system. Consequently, probiotic bacteria are emerging as a safe and natural strategy for allergy prevention and treatment. However, clinical probiotic intervention studies have so far yielded conflicting results. There is increasing awareness about the importance of host-associated factors that determine whether an individual will respond to a specific probiotic treatment, and it is therefore crucial to promote a knowledge-based instead of an empirical selection of promising probiotic strains and their administration regimen. In this Review, we summarize the insights from animal model studies of allergic disease, which reveal how host-related factors – such as genetic makeup, sex, age and microbiological status – can impact the outcomes of preventive or curative probiotic treatment. We explore why and how these factors can influence the results of probiotic studies and negatively impact the reproducibility in animal experiments. These same factors might profoundly influence the outcomes of human clinical trials, and can potentially explain the conflicting results from probiotic intervention studies. Therefore, we also link these host-related factors to human probiotic study outcomes in the context of airway allergies., Summary: This Review discusses the host factors that influence the outcomes of in vivo probiotic interventions in allergy, focusing on genetics, sex, age and microbiological status in mouse models of allergic disease.

International audience; The first European Rhinology Research Forum organized by the European Forum for Research and Education in Allergy and Airway Diseases (EUFOREA) was held in the Royal Academy of Medicine in Brussels on 17th and 18th November 2016, in collaboration with the European Rhinologic Society (ERS) and the Global Allergy and Asthma European Network (GA2LEN). One hundred and thirty participants (medical doctors from different specialties, researchers, as well as patients and industry representatives) from 27 countries took part in the multiple perspective discussions including brainstorming sessions on care pathways and research needs in rhinitis and rhinosinusitis. The debates started with an overview of the current state of the art, including weaknesses and strengths of the current practices, followed by the identification of essential research needs, thoroughly integrated in the context of Precision Medicine (PM), with personalized care, prediction of success of treatment, participation of the patient and prevention of disease as key principles for improving current clinical practices. This report provides a concise summary of the outcomes of the brainstorming sessions of the European Rhinology Research Forum 2016.

Probiotic Lactobacillus strains are widely used to benefit human and animal health, although the exact mechanisms behind their interactions with the host and the microbiota are largely unknown. Fluorescent tagging of live probiotic cells is an important tool to unravel their modes of action. In this study, the implementation of different heterologously expressed fluorescent proteins for the labelling of the model probiotic strains Lactobacillus rhamnosusGG (gastrointestinal) and Lactobacillus rhamnosusGR-1 (vaginal) was explored. Heterologous expression of mTagBFP2 and mCherry resulted in long-lasting fluorescence of L. rhamnosusGG and GR-1 cells, using the nisin-controlled expression (NICE) system. These novel fluorescent strains were then used to study in vitro aspects of their microbe-microbe and microbe-host interactions. Lactobacillus rhamnosusGG and L. rhamnosusGR-1 expressing mTagBFP2 and mCherry could be visualized in mixed-species biofilms, where they inhibited biofilm formation by Salmonella Typhimurium-gfpmut3 expressing the green fluorescent protein. Likewise, fluorescent L. rhamnosusGG and L. rhamnosusGR-1 were implemented for the visualization of their adhesion patterns to intestinal epithelial cell cultures. The fluorescent L. rhamnosus strains developed in this study can therefore serve as novel tools for the study of probiotic interactions with their environment. ispartof: Microbial Biotechnology vol:11 issue:2 pages:317-331 ispartof: location:United States status: published

Summary Several studies have recently pointed towards an increased occurrence and prevalence of several taxa of the lactic acid bacteria (LAB) in the microbiota of the upper respiratory tract (URT) under healthy conditions versus disease. These include several species of the Lactobacillales such as Lacticaseibacillus casei, Lactococcus lactis and Dolosigranulum pigrum. In addition to physiological studies on their potential beneficial functions and their long history of safe use as probiotics in other human body sites, LAB are thus increasingly to be explored as alternative or complementary treatment for URT diseases. This review highlights the importance of lactic acid bacteria in the respiratory tract and their potential as topical probiotics for this body site. We focus on the potential probiotic properties and adaptation factors that are needed for a bacterial strain to optimally exert its beneficial activity in the respiratory tract. Furthermore, we discuss a range of in silico, in vitro and in vivo models needed to obtain better insights into the efficacy and adaptation factors specifically for URT probiotics. Such knowledge will facilitate optimal strain selection in order to conduct rigorous clinical studies with the most suitable probiotic strains. Despite convincing evidence from microbiome association and in vitro studies, the clinical evidence for oral or topical probiotics for common URT diseases such as chronic rhinosinusitis (CRS) needs further substantiation., Several studies have recently pointed towards an increased occurrence and prevalence of several taxa of the lactic acid bacteria (LAB) in the microbiota of the upper respiratory tract (URT) under healthy conditions versus disease. This review highlights the importance of lactic acid bacteria in the respiratory tract, and their potential as topical probiotics for this body site. We focus on the potential probiotic properties and adaptation factors that are needed for a bacterial strain to optimally exert its beneficial activity in the respiratory tract.

ObjectivesPrimary care urgently needs treatments for COVID-19 patients because current options are limited, while these patients account for more than 90% of the people infected with SARS-CoV-2.MethodsWe evaluated a throat spray containing three Lactobacillaceae strains with broad antiviral properties in a randomized double-blind placebo-controlled trial. Seventy-eight eligible COVID-19 patients were randomized to verum (n=41) and placebo (n=37) within 96 hours of positive PCR-based SARS-CoV-2 diagnosis and per-protocol analysis was performed. Symptoms and severity were reported daily via an online diary. Combined nose-throat swabs and dried blood spots were collected at regular time points in the study.ResultsThe daily reported symptoms were highly variable, with no added benefit for symptom resolution in the verum group. Specific monitoring of the applied lactobacilli strains showed that they were detectable via microbiome (27%) and qPCR analysis (82%) of the verum group. Their relative abundances were also negatively correlated with the acute symptom score. At the end of the trial, a trend towards lower SARS-CoV-2 viral loads was observed for the verum group (2/30, 6.7% positive) compared to the placebo group (7/27, 26% positive) (p = 0.07).ConclusionsDespite a trend towards lower SARS-CoV-2 viral loads at the end of the trial and a negative correlation between relative abundances of the applied lactobacilli in the microbiome and acute symptoms, we did not observe a significant effect on overall symptom score for the verum group. This suggests that studies with earlier application of the spray in larger study populations are needed to further assess application potential.