Faecalibacterium duncaniae as a novel next generation probiotic against influenza.

The gut-lung axis is critical during viral respiratory infections such as influenza. Gut dysbiosis during infection translates into a massive drop of microbially produced short-chain fatty acids (SCFAs). Among them, butyrate is important during influenza suggesting that microbiome-based therapeutics targeting butyrate might hold promises. The butyrate-producing bacterium Faecalibacterium duncaniae (formerly referred to as F. prausnitzii) is an emerging probiotic with several health-promoting characteristics. To investigate the potential effects of F. duncaniae on influenza outcomes, mice were gavaged with live F. duncaniae (A2-165 or I-4574 strains) five days before infection. Supplementation of F. duncaniae was associated with less severe disease, a lower pulmonary viral load, and lower levels of lung inflammation. F. duncaniae supplementation impacted on gut dysbiosis induced by infection, as assessed by 16S rRNA sequencing. Interestingly, F. duncaniae administration was associated with a recovery in levels of SCFAs (including butyrate) in infected animals. The live form of F. duncaniae was more potent that the pasteurized form in improving influenza outcomes. Lastly, F. duncaniae partially protected against secondary (systemic) bacterial infection. We conclude that F. duncaniae might serve as a novel next generation probiotic against acute viral respiratory diseases.

Kynurenine Pathway in Respiratory Diseases.

The kynurenine pathway is the primary route for tryptophan catabolism and has received increasing attention as its association with inflammation and the immune system has become more apparent. This review provides a broad overview of the kynurenine pathway in respiratory diseases, from the initial observations to the characterization of the different cell types involved in the synthesis of kynurenine metabolites and the underlying immunoregulatory mechanisms. With a focus on respiratory infections, the various attempts to characterize the kynurenine/tryptophan (K/T) ratio as an inflammatory marker are reviewed. Its implication in chronic lung inflammation and its exacerbation by respiratory pathogens is also discussed. The emergence of preclinical interventional studies targeting the kynurenine pathway opens the way for the future development of new therapies.

IL-20 Cytokines Are Involved in the Repair of Airway Epithelial Barrier: Implication in Exposure to Cigarette Smoke and in COPD Pathology.

BACKGROUND: Dysregulated inflammation as seen in chronic obstructive pulmonary disease (COPD) is associated with impaired wound healing. IL-20 cytokines are known to be involved in wound healing processes. The purpose of this study was to use ex vivo and in vitro approaches mimicking COPD to evaluate the potential modulatory role of interleukin-20 (IL-20) on the inflammatory and healing responses to epithelial wounding. METHODS: The expression of IL-20 cytokines and their receptors was investigated in lung-derived samples collected from non-COPD and COPD patients, from mice chronically exposed to cigarette smoke and from airway epithelial cells from humans and mice exposed in vitro to cigarette smoke. To investigate the role of IL-20 cytokines in wound healing, experiments were performed using a blocking anti-IL-20Rb antibody. RESULTS: Of interest, IL-20 cytokines and their receptors were expressed in bronchial mucosa, especially on airway epithelial cells. Their expression correlated with the disease severity. Blocking these cytokines in a COPD context improved the repair processes after a lesion induced by scratching the epithelial layer. CONCLUSIONS: Collectively, this study highlights the implication of IL-20 cytokines in the repair of the airway epithelium and in the pathology of COPD. IL-20 subfamily cytokines might provide therapeutic benefit for patients with COPD to improve epithelial healing.

Exposure to atmospheric Ag, TiO2, Ti and SiO2 engineered nanoparticles modulates gut inflammatory response and microbiota in mice.

The development of nanotechnologies is leading to greater abundance of engineered nanoparticles (EN) in the environment, including in the atmospheric air. To date, it has been shown that the most prevalent EN found in the air are silver (Ag), titanium dioxide (TiO2), titanium (Ti), and silicon dioxide (SiO2). As the intestinal tract is increasingly recognized as a target for adverse effects induced by inhalation of air particles, the aim of this study was to assess the impact of these 4 atmospheric EN on intestinal inflammation and microbiota. We assessed the combined toxicity effects of Ag, Ti, TiO2, and SiO2 following a 28-day inhalation protocol in male and female mice. In distal and proximal colon, and in jejunum, EN mixture inhalation did not induce overt histological damage, but led to a significant modulation of inflammatory cytokine transcript abundance, including downregulation of Tnfα, Ifnγ, Il1ß, Il17a, Il22, IL10, and Cxcl1 mRNA levels in male jejunum. A dysbiosis was observed in cecal microbiota of male and female mice exposed to the EN mixture, characterized by sex-dependent modulations of specific bacterial taxa, as well as sex-independent decreased abundance of the Eggerthellaceae family. Under dextran sodium sulfate-induced inflammatory conditions, exposure to the EN mixture increased the development of colitis in both male and female mice. Moreover, the direct dose-response effects of individual and mixed EN on gut organoids was studied and Ag, TiO2, Ti, SiO2, and EN mixture were found to generate specific inflammatory responses in the intestinal epithelium. These results indicate that the 4 most prevalent atmospheric EN could have the ability to disturb intestinal homeostasis through direct modulation of cytokine expression in gut epithelium, and by altering the inflammatory response and microbiota composition following inhalation.

IL-20 Cytokines Are Involved in Epithelial Lesions Associated with Virus-Induced COPD Exacerbation in Mice.

(1) Background: viral infections are a frequent cause of chronic obstructive pulmonary disease (COPD) exacerbations, which are responsible for disease progression and mortality. Previous reports showed that IL-20 cytokines facilitate bacterial lung infection, but their production and their role in COPD and viral infection has not yet been investigated. (2) Methods: C57BL/6 WT and IL-20 Rb KO mice were chronically exposed to air or cigarette smoke (CS) to mimic COPD. Cytokine production, antiviral response, inflammation and tissue damages were analyzed after PVM infection. (3) Results: CS exposure was associated with an increase in viral burden and antiviral response. PVM infection in CS mice enhanced IFN-γ, inflammation and tissue damage compared to Air mice. PVM infection and CS exposure induced, in an additive manner, IL-20 cytokines expression and the deletion of IL-20 Rb subunit decreased the expression of interferon-stimulated genes and the production of IFN-λ2/3, without an impact on PVM replication. Epithelial cell damages and inflammation were also reduced in IL-20 Rb-/- mice, and this was associated with reduced lung permeability and the maintenance of intercellular junctions. (4) Conclusions: PVM infection and CS exposure additively upregulates the IL-20 pathway, leading to the promotion of epithelial damages. Our data in our model of viral exacerbation of COPD identify IL-20 cytokine as a potential therapeutic target.

An innate contribution of human nicotinic receptor polymorphisms to COPD-like lesions.

Chronic Obstructive Pulmonary Disease is a generally smoking-linked major cause of morbidity and mortality. Genome-wide Association Studies identified a locus including a non-synonymous single nucleotide polymorphism in CHRNA5, rs16969968, encoding the nicotinic acetylcholine receptor α5 subunit, predisposing to both smoking and Chronic Obstructive Pulmonary Disease. Here we report that nasal polyps from rs16969968 non-smoking carriers exhibit airway epithelium remodeling and inflammation. These hallmarks of Chronic Obstructive Pulmonary Disease occur spontaneously in mice expressing human rs16969968. They are significantly amplified after exposure to porcine pancreatic elastase, an emphysema model, and to oxidative stress with a polymorphism-dependent alteration of lung function. Targeted rs16969968 expression in epithelial cells leads to airway remodeling in vivo, increased proliferation and production of pro-inflammatory cytokines through decreased calcium entry and increased adenylyl-cyclase activity. We show that rs16969968 directly contributes to Chronic Obstructive Pulmonary Disease-like lesions, sensitizing the lung to the action of oxidative stress and injury, and represents a therapeutic target.

Erratum: Rémy et al. Modelling the Impact of Chronic Cigarette Smoke Exposure in Obese Mice: Metabolic, Pulmonary, Intestinal, and Cardiac Issues. Nutrients 2020, 12, 827.

The authors have requested that the following changes be made to their paper [...].

Insights into the Mechanism and Catalysis of Peptide Thioester Synthesis by Alkylselenols Provide a New Tool for Chemical Protein Synthesis.

While thiol-based catalysts are widely employed for chemical protein synthesis relying on peptide thioester chemistry, this is less true for selenol-based catalysts whose development is in its infancy. In this study, we compared different selenols derived from the selenocysteamine scaffold for their capacity to promote thiol-thioester exchanges in water at mildly acidic pH and the production of peptide thioesters from bis(2-sulfanylethyl)amido (SEA) peptides. The usefulness of a selected selenol compound is illustrated by the total synthesis of a biologically active human chemotactic protein, which plays an important role in innate and adaptive immunity.

The Toll-Like Receptor 5 agonist flagellin prevents Non-typeable Haemophilus influenzae-induced infection in cigarette smoke-exposed mice.

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. The major bacterial cause of COPD exacerbations is non-typeable Haemophilus influenzae (NTHi). 25 to over 80% of cases are associated with NTHi. This susceptibility to infection involves a defective production of interleukin (IL)-22 which plays an important role in mucosal defense. Prophylactic administration of flagellin, a Toll-like receptor 5 (TLR5) agonist, protects healthy mice against respiratory pathogenic bacteria. We hypothesized that TLR5-mediated stimulation of lung immunity might prevent COPD exacerbations. Mice chronically exposed to cigarette smoke (CS), which presented COPD symptoms, were infected with NTHi and intraperitoneally treated with recombinant flagellin following a prophylactic or therapeutic protocol. Compared with control, cigarette smoke-exposed mice treated with flagellin showed a lower bacterial load in the airways, the lungs and the blood. This protection was associated with an early neutrophilia, a lower production of pro-inflammatory cytokines and an increased IL-22 production. Flagellin treatment decreased the recruitment of inflammatory cells and the lung damages related to exacerbation. Morover, the protective effect of flagellin against NTHi was altered by treatment with anti-IL-22 blocking antibodies in cigarette smoke-exposed mice and in Il22-/- mice. The effect of flagellin treatment did not implicated the anti-bacterial peptides calgranulins and defensin-ß2. This study shows that stimulation of innate immunity by a TLR5 ligand is a potent antibacterial treatment in CS-exposed mice, suggesting innovative therapeutic strategies against acute exacerbation in COPD.

Impact of domestic mould exposure on Aspergillus biomarkers and lung function in patients with chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease (COPD) are frequently colonised or sensitised by Aspergillus, but clinical significance remains unclear. Furthermore, little is known on the impact of indoor mould exposure during COPD. In this study, we assessed the relationship between domestic mould exposure, Aspergillus biomarkers and COPD severity during acute exacerbation and at stable state. Aspergillus section Fumigati culture in sputum and anti-Aspergillus antibodies detection (IgG and precipitins) were followed up in COPD patients that were prospectively recruited during exacerbation (n = 62), and underwent a visit at stable state after 18 months (n = 33). Clinical characteristics were collected at inclusion. Electrostatic dust collectors (EDCs) were used to measure domestic mould contamination. Aspergillus section Fumigati was more frequently detected during exacerbation (16.9%) than at stable state (4.0%), but the frequency of patients presenting with anti-Aspergillus antibodies was similar (32.2% and 33.3%, respectively). Aspergillus section Fumigati detection was associated with a higher body-mass index (BMI) during exacerbation, whereas patients with anti-Aspergillus antibodies presented a lower BMI and forced expiratory volume in 1 s, as well as a higher frequency of inhaled corticoids and higher total mould and Penicillium exposure at final visit (P < 0.05). The frequency of patients with anti-Aspergillus antibodies was higher for total mould counts >30 CFU/cm2 (P = 0.03). Aspergillosis was diagnosed in 2 patients (6.1%) who presented increased levels of antibodies. Our data suggest that anti-Aspergillus antibodies are associated with chronic lung function alteration and/or domestic mould exposure, thereby supporting the consideration of indoor mould contamination and anti-Aspergillus antibodies kinetics in COPD management.

A New Strategy to Preserve and Assess Oxygen Consumption in Murine Tissues.

Mitochondrial dysfunctions are implicated in several pathologies, such as metabolic, cardiovascular, respiratory, and neurological diseases, as well as in cancer and aging. These metabolic alterations are usually assessed in human or murine samples by mitochondrial respiratory chain enzymatic assays, by measuring the oxygen consumption of intact mitochondria isolated from tissues, or from cells obtained after physical or enzymatic disruption of the tissues. However, these methodologies do not maintain tissue multicellular organization and cell-cell interactions, known to influence mitochondrial metabolism. Here, we develop an optimal model to measure mitochondrial oxygen consumption in heart and lung tissue samples using the XF24 Extracellular Flux Analyzer (Seahorse) and discuss the advantages and limitations of this technological approach. Our results demonstrate that tissue organization, as well as mitochondrial ultrastructure and respiratory function, are preserved in heart and lung tissues freshly processed or after overnight conservation at 4 °C. Using this method, we confirmed the repeatedly reported obesity-associated mitochondrial dysfunction in the heart and extended it to the lungs. We set up and validated a new strategy to optimally assess mitochondrial function in murine tissues. As such, this method is of great potential interest for monitoring mitochondrial function in cohort samples.

Childhood asthma heterogeneity at the era of precision medicine: Modulating the immune response or the microbiota for the management of asthma attack.

Exacerbations are a main characteristic of asthma. In childhood, the risk is increasing with severity. Exacerbations are a strong phenotypic marker, particularly of severe and therapy-resistant asthma. These early-life events may influence the evolution and be involved in lung function decline. In children, asthma attacks are facilitated by exposure to allergens and pollutants, but are mainly triggered by microbial agents. Multiple studies have assessed immune responses to viruses, and to a lesser extend bacteria, during asthma exacerbation. Research has identified impairment of innate immune responses in children, related to altered pathogen recognition, interferon release, or anti-viral response. Influence of this host-microbiota dialog on the adaptive immune response may be crucial, leading to the development of biased T helper (Th)2 inflammation. These dynamic interactions may impact the presentations of asthma attacks, and have long-term consequences. The aim of this review is to synthesize studies exploring immune mechanisms impairment against viruses and bacteria promoting asthma attacks in children. The potential influence of the nature of infectious agents and/or preexisting microbiota on the development of exacerbation is also addressed. We then discuss our understanding of how these diverse host-microbiota interactions in children may account for the heterogeneity of endotypes and clinical presentations. Finally, improving the knowledge of the pathophysiological processes induced by infections has led to offer new opportunities for the development of preventive or curative therapeutics for acute asthma. A better definition of asthma endotypes associated with precision medicine might lead to substantial progress in the management of severe childhood asthma.

Severe preschool asthmatics have altered cytokine and anti-viral responses during exacerbation.

BACKGROUND: Preschool asthma/recurrent wheeze is a heterogeneous condition. Different clinical phenotypes have been described, including episodic viral wheeze (EVW), severe intermittent wheeze (SIW), and multiple-trigger wheeze (MTW). OBJECTIVE: To compare clinical, viral, and inflammatory/immune profiling at exacerbation between MTW, SIW, and EVW phenotypes. METHODS: Multicenter, prospective, observational cohort (VIRASTHMA-2). Children (1-5 years) with preschool asthma were enrolled during hospitalization for a severe exacerbation. History and anamnestic data, plasma, and nasal samples were collected at exacerbation (T1) and at steady state, 8 weeks later (T2), and sputum samples were collected at T1. RESULTS: A total of 147 children were enrolled, 37 (25%) had SIW, 18 (12.2%) EVW, and 92 (63%) MTW. They were atopic (47%), exposed to mold (22%) and cigarette smoke (50%), and prone to exacerbations (≥2 in the previous year in 70%). At exacerbation, at least one virus was isolated in 94% and rhinovirus in 75%, with no difference between phenotypes. Children with MTW and SIW phenotypes displayed lower plasma concentrations of IFN-γ (P = .002), IL-5 (P = .020), TNF-α (P = .038), IL-10 (P = .002), IFN-ß (P = .036), and CXCL10 (P = .006) and lower levels of IFN-γ (P = .047) in sputum at exacerbation than children with EVW. At T2, they also displayed lower plasma levels of IFN-γ (P = .045) and CXCL10 (P = .013). CONCLUSION: Among preschool asthmatic children, MTW and SIW, prone to exacerbations, display lower systemic levels of Th1, Th2 cytokines, pro- and anti-inflammatory cytokines, and antiviral responses during severe virus-induced exacerbation.

Modelling the Impact of Chronic Cigarette Smoke Exposure in Obese Mice: Metabolic, Pulmonary, Intestinal, and Cardiac Issues.

Unhealthy lifestyle choices, such as bad eating behaviors and cigarette smoking, have major detrimental impacts on health. However, the inter-relations between obesity and smoking are still not fully understood. We thus developed an experimental model of high-fat diet-fed obese C57BL/6 male mice chronically exposed to cigarette smoke. Our study evaluated for the first time the resulting effects of the combined exposure to unhealthy diet and cigarette smoke on several metabolic, pulmonary, intestinal, and cardiac parameters. We showed that the chronic exposure to cigarette smoke modified the pattern of body fat distribution in favor of the visceral depots in obese mice, impaired the respiratory function, triggered pulmonary inflammation and emphysema, and was associated with gut microbiota dysbiosis, cardiac hypertrophy and myocardial fibrosis.

Infection with Toxocara canis Inhibits the Production of IgE Antibodies to α-Gal in Humans: Towards a Conceptual Framework of the Hygiene Hypothesis?

α-Gal syndrome (AGS) is a type of anaphylactic reaction to mammalian meat characterized by an immunoglobulin (Ig)E immune response to the oligosaccharide α-Gal (Galα1-3Galß1-4GlcNAc-R). Tick bites seems to be a prerequisite for the onset of the allergic disease in humans, but the implication of non-tick parasites in α-Gal sensitization has also been deliberated. In the present study, we therefore evaluated the capacity of helminths (Toxocara canis, Ascaris suum, Schistosoma mansoni), protozoa (Toxoplasma gondii), and parasitic fungi (Aspergillus fumigatus) to induce an immune response to α-Gal. For this, different developmental stages of the infectious agents were tested for the presence of α-Gal. Next, the potential correlation between immune responses to α-Gal and the parasite infections was investigated by testing sera collected from patients with AGS and those infected with the parasites. Our results showed that S. mansoni and A. fumigatus produce the terminal α-Gal moieties, but they were not able to induce the production of specific antibodies. By contrast, T. canis, A. suum and T. gondii lack the α-Gal epitope. Furthermore, the patients with T. canis infection had significantly decreased anti-α-Gal IgE levels when compared to the healthy controls, suggesting the potential role of this nematode parasite in suppressing the allergic response to the glycan molecule. This rather intriguing observation is discussed in the context of the 'hygiene hypothesis'. Taken together, our study provides new insights into the relationships between immune responses to α-Gal and parasitic infections. However, further investigations should be undertaken to identify T. canis components with potent immunomodulatory properties and to assess their potential to be used in immunotherapy and control of AGS.

Production of Interleukin-20 cytokines limits bacterial clearance and lung inflammation during infection by Streptococcus pneumoniae.

BACKGROUND: Streptococcus pneumoniae is the leading cause of bacterial pneumonia worldwide. Previous reports showed that IL-20 cytokines (IL-19, IL-20 and IL-24) are induced and have an immuno-regulatory function during cutaneous infection. In the current study, our aim was to demonstrate the implication of IL-20 cytokines and their receptors and their role during experimental pneumococcal infection. METHODS: C57BL/6 mice were infected with S. pneumoniae by intranasal route. The bacterial burden, the immune response and the cytokine production were evaluated after treatment with an anti-IL-20 receptor-b (IL-20Rb) neutralizing antibody (anti-IL-20Rb). FINDINGS: Of interest, expression of IL-20 cytokines mRNA and protein were transiently increased in the lung tissue during infection. Blocking of the IL-20Rb decreased the bacterial burden both in the bronchoalveolar lavage and the lung whereas there was no significant drop in the blood. This treatment also reduced the pulmonary damages (as shown by the alveolar wall thickening), the recruitment of neutrophils and dendritic cells, and the levels of the pro-inflammatory cytokines IL-1ß and IL-6 in the lung. Administration of the anti-IL-20Rb antibody enhanced the synthesis of the antibacterial peptide LCN2. However, this effect is transient and did not affect the survival of the infected mice. INTERPRETATION: Collectively, this study highlights the implication of IL-20 related cytokines during lung infection by S. pneumoniae and might have therapeutic applications in bacterial pneumonia. FUNDINGS: This work was supported by CNRS, INSERM, INSERM-transfert, the University of Lille and the Fondation du Souffle (Paris, France).

Chronic ingestion of deoxynivalenol at human dietary levels impairs intestinal homeostasis and gut microbiota in mice.

The mycotoxin deoxynivalenol (DON) is a frequent contaminant of cereals and their by-products in areas with a moderate climate. Produced by Fusarium species, it is one of the most prevalent mycotoxins in cereal crops worldwide, and the most frequently occurring type B trichothecene in Europe. Due to its toxic properties, high stability and prevalence, the presence of DON in the food chain could represent a major public health risk. However, despite its well-known acute toxicological effects, information on the adverse effects of realistic exposure remains limited. We orally exposed mice during 9 months to DON at doses relevant for currently estimated human intake and explored the impact on various gut health parameters. DON exposure induced recruitment of regulatory B cells, and activation of regulatory T cells and dendritic cells in mesenteric lymph nodes. Several inflammatory parameters were increased in colon of DON-exposed mice, whereas inversely inflammatory markers were decreased in ileum. Histomorphological impairments were observed from the duodenum to the colon. Both colon and jejunum presented a hyperproliferation of epithelial cells and an increased expression of mature absorptive cells markers. Finally, DON exposure reshaped gut microbial structure and drastically disturbed the abundance of several bacterial phyla, families, and genera, leading to dysbiosis. Chronic oral exposure to human relevant doses of DON induces several disturbances of gut homeostasis with likely pathological implications for susceptible individuals.

Virus-triggered exacerbation in allergic asthmatic children: neutrophilic airway inflammation and alteration of virus sensors characterize a subgroup of patients.

BACKGROUND: Viruses are important triggers of asthma exacerbations. They are also detected outside of exacerbation. Alteration of anti-viral response in asthmatic patients has been shown although the mechanisms responsible for this defect remain unclear. The objective of this study was to compare in virus-infected and not-infected allergic asthmatic children, aged 6 to 16 years, admitted to hospital for a severe exacerbation, the innate immune response and especially the expression of pattern recognition receptor (PRR) and their function. METHODS: Virus identification was performed both during the exacerbation and at steady state (eight weeks later). Data assessed at both periods included clinical features, anti-viral response and inflammation (in sputum and plasma), and PRR expression/function in blood mononuclear cells. RESULTS: Viruses were identified in 46 out of 72 children (median age 8.9 years) during exacerbation, and among them, in 17 at steady state. IFN-ß, IFN-γ and IL-29 levels in sputum and plasma were similar between infected and not infected patients at both times, as well as the expression of TLR3, RIG-I and MDA5 in blood monocytes and dendritic cells. Airway inflammation in infected patients was characterized by significantly higher IL-5 concentration and eosinophil count. Compared to patients only infected at exacerbation, the re-infected children significantly exhibited lower levels of IFN-γ in plasma and sputum at exacerbation associated with modifications in PRR expression and function in blood mononuclear cells. These re-infected patients also presented an airway neutrophilic inflammation at steady state. CONCLUSION: Our results reports in asthmatic children that impaired anti-viral response during virus-induced exacerbation is more pronounced in a subgroup of patients prone to re-infection by virus. This subgroup is characterized by altered PRR function and a different pattern of airway inflammation. TRIAL REGISTRATION: This multicenter prospective study was approved by the regional investigational review board (ref: 08/07).