Moraxella catarrhalis stimulates the release of proinflammatory cytokines and prostaglandin E from human respiratory epithelial cells and monocyte-derived macrophages

Haemophilus influenzae and Moraxella catarrhalis in sputum of severe asthma with inflammasome and neutrophil activation

BACKGROUND

Because of altered airway microbiome in asthma, we analysed the bacterial species in sputum of patients with severe asthma.

METHODS

Whole genome sequencing was performed on induced sputum from non-smoking (SAn) and current or ex-smoker (SAs/ex) severe asthma patients, mild/moderate asthma (MMA) and healthy controls (HC). Data were analysed by asthma severity, inflammatory status and transcriptome-associated clusters (TACs).

RESULTS

α-diversity at the species level was lower in SAn and SAs/ex, with an increase in Haemophilus influenzae and Moraxella catarrhalis, and Haemophilus influenzae and Tropheryma whipplei, respectively, compared to HC. In neutrophilic asthma, there was greater abundance of Haemophilus influenzae and Moraxella catarrhalis and in eosinophilic asthma, Tropheryma whipplei was increased. There was a reduction in α-diversity in TAC1 and TAC2 that expressed high levels of Haemophilus influenzae and Tropheryma whipplei, and Haemophilus influenzae and Moraxella catarrhalis, respectively, compared to HC. Sputum neutrophils correlated positively with Moraxella catarrhalis and negatively with Prevotella, Neisseria and Veillonella species and Haemophilus parainfluenzae. Sputum eosinophils correlated positively with Tropheryma whipplei which correlated with pack-years of smoking. α- and β-diversities were stable at one year.

CONCLUSIONS

Haemophilus influenzae and Moraxella catarrhalis were more abundant in severe neutrophilic asthma and TAC2 linked to inflammasome and neutrophil activation, while Haemophilus influenzae and Tropheryma whipplei were highest in SAs/ex and in TAC1 associated with highest expression of IL-13 type 2 and ILC2 signatures with the abundance of Tropheryma whipplei correlating positively with sputum eosinophils. Whether these bacterial species drive the inflammatory response in asthma needs evaluation.

Nasal Symptoms Reduction and Decreased Neutrophilia in Japanese Cedar Pollinosis With Prophylactic Treatment With a Combination of Montelukast, Fexofenadine, and Fluticasone Nasal Spray

Background and Objective

We reported neutrophil-associated tissue damage in cedar pollinosis subjects with refractory nasal symptoms prior to pollinosis season. Because the leukotriene receptor antagonist, montelukast, can inhibit neutrophil recruitment and activation, we investigated its effects on symptom relief and nasal neutrophilia in pollinosis subjects in the preseason.

Methods

In the pollinosis preseason, symptomatic (PreSyP, n = 149) and asymptomatic subjects (PreAsP, n = 145) were prophylactically treated, and in season symptomatic subjects (InSyP, n = 134) were treated. Individuals were assigned to 1 of 2 treatment protocols: administration of cetirizine and fluticasone nasal spray (Cet-Flu) or montelukast, fexofenadine, and fluticasone nasal spray (Mo-Fex-Flu). Differences in symptom relief and inflammatory cell infiltration in nasal swabs were investigated.

Results

In pollen season, 59% of PreSyP subjects given Cet-Flu and 88% of those treated with Mo-Fex-Flu had none or mild symptoms ( P < .00001). In PreAsP subjects in season, 71% of Cet-Flu and 98% of Mo-Fex-Flu recipients had none to mild symptoms ( P < .0000001). The proportions of subjects in the PreSyP group with nasal swabs with neutrophils 1+ to 3+ before and after treatment by Mo-Fex-Flu were 59% and 18%, respectively ( P < .0001), and in PreAsyP, subjects with neutrophils 2+ to 3+ were 17% and 5%, respectively ( P = .034). In PreSyP, a significant reduction in the percentage of subjects with mast cells >1+ was seen following both Cet-Flu ( P = .027) and Mo-Fex-Flu ( P = .0014) treatments.

Conclusion

In PreSyP and PreAsP subjects, treatments with Mo-Fex-Flu were more effective than Cet-Flu to reduce nasal symptom scores. These effects were associated with reduction in the number of neutrophils and mast cells in nasal swabs.

Characterisation of gut, lung, and upper airways microbiota in patients with non-small cell lung carcinoma: Study protocol for case-control observational trial

BACKGROUND

Several studies have confirmed the important role of the gut microbiota in the regulation of immune functions and its correlation with different diseases, including cancer. While brain-gut and liver-gut axes have already been demonstrated, the existence of a lung-gut axis has been suggested more recently, with the idea that changes in the gut microbiota could affect the lung microbiota, and vice versa. Likewise, the close connection between gut microbiota and cancer of proximal sites (intestines, kidneys, liver, etc.) is already well established. However, little is known whether there is a similar relation when looking at world's number one cause of death from cancer-lung cancer.

OBJECTIVE

Firstly, this study aims to characterise the gut, lung, and upper airways (UAs) microbiota in patients with non-small cell lung cancer (NSCLC) treated with surgery or neoadjuvant chemotherapy plus surgery. Secondly, it aims to evaluate a chemotherapy effect on site-specific microbiota and its influence on immune profile. To our knowledge, this is the 1st study that will analyse multi-site microbiota in NSCLC patients along with site-specific immune response.

METHODS

The study is a case-controlled observational trial. Forty NSCLC patients will be divided into 2 groups depending on their anamnesis: Pchir, patients eligible for surgery, or Pct-chir, patients eligible for neoadjuvant chemotherapy plus surgery. Composition of the UAs (saliva), gut (faeces), and lung microbiota (from broncho-alveolar lavage fluid (BALF) and 3 lung pieces: "healthy" tissue distal to tumour, peritumoural tissue and tumour itself) will be analysed in both groups. Immune properties will be evaluated on the local (evaluation of the tumour immune cell infiltrate, tumour classification and properties, immune cell phenotyping in BALF; human neutrophil protein (HNP) 1-3, β-defensin 2, and calprotectin in faeces) and systemic level (blood cytokine and immune cell profile). Short-chain fatty acids (SCFAs) (major products of bacterial fermentation with an effect on immune system) will be dosed in faecal samples. Other factors such as nutrition and smoking status will be recorded for each patient. We hypothesise that smoking status and tumour type/grade will be major factors influencing both microbiota and immune/inflammatory profile of all sampling sites. Furthermore, due to non-selectivity, the same effect is expected from chemotherapy.

Microbiome in the pathogenesis of cystic fibrosis and lung transplant-related disease

Significant advances in culture-independent methods have expanded our knowledge about the diversity of the lung microbial environment. Complex microorganisms and microbial communities can now be identified in the distal airways in a variety of respiratory diseases, including cystic fibrosis (CF) and the posttransplantation lung. Although there are significant methodologic concerns about sampling the lung microbiome, several studies have now shown that the microbiome of the lower respiratory tract is distinct from the upper airway. CF is a disease characterized by chronic airway infections that lead to significant morbidity and mortality. Traditional culture-dependent methods have identified a select group of pathogens that cause exacerbations in CF, but studies using bacterial 16S rRNA gene-based microarrays have shown that the CF microbiome is an intricate and dynamic bacterial ecosystem, which influences both host immune health and disease pathogenesis. These microbial communities can shift with external influences, including antibiotic exposure. In addition, there have been a number of studies suggesting a link between the gut microbiome and respiratory health in CF. Compared with CF, there is significantly less knowledge about the microbiome of the transplanted lung. Risk factors for bronchiolitis obliterans syndrome, one of the leading causes of death, include microbial infections. Lung transplant patients have a unique lung microbiome that is different than the pretransplanted microbiome and changes with time. Understanding the host-pathogen interactions in these diseases may suggest targeted therapies and improve long-term survival in these patients.

Looking Beyond Respiratory Cultures: Microbiome-Cytokine Signatures of Bacterial Pneumonia and Tracheobronchitis in Lung Transplant Recipients

Bacterial pneumonia and tracheobronchitis are diagnosed frequently following lung transplantation. The diseases share clinical signs of inflammation and are often difficult to differentiate based on culture results. Microbiome and host immune-response signatures that distinguish between pneumonia and tracheobronchitis are undefined. Using a retrospective study design, we selected 49 bronchoalveolar lavage fluid samples from 16 lung transplant recipients associated with pneumonia (n = 8), tracheobronchitis (n = 12) or colonization without respiratory infection (n = 29). We ensured an even distribution of Pseudomonas aeruginosa or Staphylococcus aureus culture-positive samples across the groups. Bayesian regression analysis identified non-culture-based signatures comprising 16S ribosomal RNA microbiome profiles, cytokine levels and clinical variables that characterized the three diagnoses. Relative to samples associated with colonization, those from pneumonia had significantly lower microbial diversity, decreased levels of several bacterial genera and prominent multifunctional cytokine responses. In contrast, tracheobronchitis was characterized by high microbial diversity and multifunctional cytokine responses that differed from those of pneumonia-colonization comparisons. The dissimilar microbiomes and cytokine responses underlying bacterial pneumonia and tracheobronchitis following lung transplantation suggest that the diseases result from different pathogenic processes. Microbiomes and cytokine responses had complementary features, suggesting that they are closely interconnected in the pathogenesis of both diseases.

Involvement of Staphylococcus aureus and Moraxella catarrhalis in Japanese cedar pollinosis

BACKGROUND AND OBJECTIVE

From mid February to the end of March, each year ∼30% of Japanese have Japanese cedar pollinosis. Moreover, 10-50% of patients with this pollinosis exhibit nasal manifestations in the preseason. These patients have a predominance of neutrophils but not eosinophils in nasal swabs and high carriage of Staphylococcus aureus. We hypothesized that S. aureus or other bacteria and associated neutrophilia were involved in preseasonal symptoms.

METHODS

Cytology and bacterial colony growth were assessed in nasal swabs in the groups of asymptomatic patients in the preseason (PreAsP) (n = 53) and symptomatic patients in the preseason (PreSyP) (n = 60), and in group of symptomatic patients in season (InSyP) (n = 72).

RESULTS

In the preseason, high neutrophilia was present in only 20% of the PreAsP group but in 47% of the PreSyP group (p < 0.01). Nasal carriage of S. aureus in the PreAsP and PreSyP groups were 79%, 75%, respectively, whereas, for Moraxella catarrhalis, these were 9% versus 25% (PreAsP versus PreSyP group; p < 0.05). In patients with positive results for S. aureus and M. catarrhalis, the degrees of neutrophilia (-, ±, +, 2+, 3+) in the PreSyP group were larger than in the PreAsP groups (p < 0.01). In the PreSyP group, the magnitude of neutrophilia was greater (p < 0.05) in subgroups with more colonies of S. aureus than in subgroups with fewer colonies.

CONCLUSION

Nasal symptoms in the preseason are associated with neutrophilia and nasal colonization with S. aureus and M. catarrhalis. Patients with symptoms in the preseason had improved symptom scores when given prophylactic treatment early in season but had more-severe symptom scores late in season than asymptomatic patients in the preseason. Neutrophil-associated tissue damage related to bacterial colonization may underlie these associations.

Are respiratory viruses involved in preseasonal symptoms or severity in Japanese cedar pollinosis?

BACKGROUND

Respiratory virus infections are involved in asthma exacerbations. However, there are no reports of the relationship between respiratory virus infections and Japanese cedar pollinosis.

OBJECTIVE

We studied the relationship between respiratory viral infection and the appearance of preseasonal symptoms and the severity of seasonal symptoms in Japanese cedar pollinosis.

METHODS

In 36 patients with asthma and with no symptoms (PreAsyP) and 54 patients with asthma and with symptoms (PreSyP) before the cedar pollen shedding commenced (preseason), and 37 patients with mild-to-moderate severity (InMild/Mod) and 45 patients with severe to extreme severity (InSev/Ext) after cedar shedding commenced (in season), the occurrence of respiratory viruses and nasal smear cytology were examined.

RESULTS

In total, seven infections with respiratory viruses were detected among the subjects. Human rhinovirus (HRV) C infection was detected in one subject in each of the PreAsyP and PreSyP groups, and one HRVA infection occurred in the InMild/Mod group. In the InSev/Ext group, one HRVA, one HRVC, one respiratory syncytial virus, and one human metapneumovirus were detected. There was no significant difference in the rate of detection of viral infections between the PreAsyP and the PreSyP groups (p = 0.077), and between the InMild/Mod group and the InSev/Ext group (p = 0.24, Wilcoxon rank sum test). When cells types in nasal smears were identified and their abundance examined, the rate of neutrophilia in the subjects in the PreSyP group was 54%, which was statistically higher (p < 0.01) than the subjects in the PreAsyP group (25%). Interestingly, in the subjects in the InSev/Ext group, the proportion of eosinophils (40%) was larger (p < 0.05) than in the subjects in the InMild/Mod group (19%).

CONCLUSION

These results provided no evidence that respiratory virus infections contributed to preseasonal symptoms and severity in season of Japanese cedar pollinosis. Nasal neutrophilia was related to preseasonal symptoms, whereas nasal eosinophilia was related to severity of symptoms during the pollen season.

Identification of an outer membrane lipoprotein involved in nasopharyngeal colonization by Moraxella catarrhalis in an animal model

Colonization of the human nasopharynx by Moraxella catarrhalis is presumed to involve attachment of this bacterium to the mucosa. DNA microarray analysis was used to determine whether attachment of M. catarrhalis to human bronchial epithelial (HBE) cells in vitro affected gene expression in this bacterium. Attachment affected expression of at least 454 different genes, with 163 being upregulated and 291 being downregulated. Among the upregulated genes was one (ORF113) previously annotated as encoding a protein with some similarity to outer membrane protein A (OmpA). The protein encoded by ORF113 was predicted to have a signal peptidase II cleavage site, and globomycin inhibition experiments confirmed that this protein was indeed a lipoprotein. The ORF113 protein also contained a predicted peptidoglycan-binding domain in its C-terminal half. The use of mutant and recombinant M. catarrhalis strains confirmed that the ORF113 protein was present in outer membrane preparations, and this protein was also shown to be at least partially exposed on the bacterial cell surface. A mutant unable to produce the ORF113 protein showed little or no change in its growth rate in vitro, in its ability to attach to HBE cells in vitro, or in its autoagglutination characteristics, but it did exhibit a reduced ability to survive in the chinchilla nasopharynx. This is the first report of a lipoprotein essential to the ability of M. catarrhalis to persist in an animal model.

Moraxella catarrhalis: from interactions with the host immune system to vaccine development

Moraxella catarrhalis is a human-restricted commensal that over the last two decades has developed into an emerging respiratory tract pathogen. The bacterial species is equipped with various adhesins to facilitate its colonization. Successful evasion of the human immune system is a prerequisite for Moraxella infection. This strategy involves induction of an excessive proinflammatory response, intervention of granulocyte recruitment to the infection site, activation of selected pattern recognition receptors and cellular adhesion molecules to counteract the host bacteriolytic attack, as well as, finally, reprogramming of antigen presenting cells. Host immunomodulator molecules are also exploited by Moraxella to aid in resistance against complement killing and host bactericidal molecules. Thus, breaking the basis of Moraxella immune evasion mechanisms is fundamental for future invention of effective therapy in controlling Moraxella infection.

Divergent pro-inflammatory profile of human dendritic cells in response to commensal and pathogenic bacteria associated with the airway microbiota

Recent studies using culture-independent methods have characterized the human airway microbiota and report microbial communities distinct from other body sites. Changes in these airway bacterial communities appear to be associated with inflammatory lung disease, yet the pro-inflammatory properties of individual bacterial species are unknown. In this study, we compared the immune stimulatory capacity on human monocyte-derived dendritic cells (DCs) of selected airway commensal and pathogenic bacteria predominantly associated with lungs of asthma or COPD patients (pathogenic Haemophillus spp. and Moraxella spp.), healthy lungs (commensal Prevotella spp.) or both (commensal Veillonella spp. and Actinomyces spp.). All bacteria were found to induce activation of DCs as demonstrated by similar induction of CD83, CD40 and CD86 surface expression. However, asthma and COPD-associated pathogenic bacteria provoked a 3-5 fold higher production of IL-23, IL-12p70 and IL-10 cytokines compared to the commensal bacteria. Based on the differential cytokine production profiles, the studied airway bacteria could be segregated into three groups (Haemophilus spp. and Moraxella spp. vs. Prevotella spp. and Veillonella spp. vs. Actinomyces spp.) reflecting their pro-inflammatory effects on DCs. Co-culture experiments found that Prevotella spp. were able to reduce Haemophillus influenzae-induced IL-12p70 in DCs, whereas no effect was observed on IL-23 and IL-10 production. This study demonstrates intrinsic differences in DC stimulating properties of bacteria associated with the airway microbiota.

Identification of a bacteriocin and its cognate immunity factor expressed by Moraxella catarrhalis

Background

Bacteriocins are antimicrobial proteins and peptides ribosomally synthesized by some bacteria which can effect both intraspecies and interspecies killing.

Results

Moraxella catarrhalis strain E22 containing plasmid pLQ510 was shown to inhibit the growth of M. catarrhalis strain O35E. Two genes (mcbA and mcbB) in pLQ510 encoded proteins predicted to be involved in the secretion of a bacteriocin. Immediately downstream from these two genes, a very short ORF (mcbC) encoded a protein which had some homology to double-glycine bacteriocins produced by other bacteria. A second very short ORF (mcbI) immediately downstream from mcbC encoded a protein which had no significant similarity to other proteins in the databases. Cloning and expression of the mcbI gene in M. catarrhalis O35E indicated that this gene encoded the cognate immunity factor. Reverse transcriptase-PCR was used to show that the mcbA, mcbB, mcbC, and mcbI ORFs were transcriptionally linked. This four-gene cluster was subsequently shown to be present in the chromosome of several M. catarrhalis strains including O12E. Inactivation of the mcbA, mcbB, or mcbC ORFs in M. catarrhalis O12E eliminated the ability of this strain to inhibit the growth of M. catarrhalis O35E. In co-culture experiments involving a M. catarrhalis strain containing the mcbABCI locus and one which lacked this locus, the former strain became the predominant member of the culture after overnight growth in broth.

Conclusion

This is the first description of a bacteriocin and its cognate immunity factor produced by M. catarrhalis. The killing activity of the McbC protein raises the possibility that it might serve to lyse other M. catarrhalis strains that lack the mcbABCI locus, thereby making their DNA available for lateral gene transfer.

Outer membrane porin M35 of Moraxella catarrhalis mediates susceptibility to aminopenicillins

Background

The outer membrane protein M35 is a conserved porin of type 1 strains of the respiratory pathogen Moraxella catarrhalis. It was previously shown that M35 is involved in the uptake of essential nutrients required for bacterial growth and for nasal colonization in mice. The aim of this study was (i) to characterize the potential roles of M35 in the host-pathogen interactions considering the known multifunctionality of porins and (ii) to characterize the degree of conservation in the phylogenetic older subpopulation (type 2) of M. catarrhalis.

Results

Isogenic m35 mutants of the type 1 strains O35E, 300 and 415 were tested for their antimicrobial susceptibility against 15 different agents. Differences in the MIC (Minimum Inhibitory Concentration) between wild-type and mutant strains were found for eight antibiotics. For ampicillin and amoxicillin, we observed a statistically significant 2.5 to 2.9-fold MIC increase (p < 0.03) in the m35 mutants. Immunoblot analysis demonstrated that human saliva contains anti-M35 IgA. Wild-type strains and their respective m35 mutants were indistinguishable with respect to the phenotypes of autoagglutination, serum resistance, iron acquisition from human lactoferrin, adherence to and invasion of respiratory tract epithelial cells, and proinflammatory stimulation of human monocytes. DNA sequencing of m35 from the phylogenetic subpopulation type 2 strain 287 revealed 94.2% and 92.8% identity on the DNA and amino acid levels, respectively, in comparison with type 1 strains.

Conclusion

The increase in MIC for ampicillin and amoxicillin, respectively, in the M35-deficient mutants indicates that this porin affects the outer membrane permeability for aminopenicillins in a clinically relevant manner. The presence of IgA antibodies in healthy human donors indicates that M35 is expressed in vivo and recognized as a mucosal antigen by the human host. However, immunoblot analysis of human saliva suggests the possibility of antigenic variation of immunoreactive epitopes, which warrants further analysis before M35 can be considered a potential vaccine candidate.

Outer membrane protein UspA1 and lipooligosaccharide are involved in invasion of human epithelial cells by Moraxella catarrhalis

Invasion of non-professional phagocytes is a strategy employed by several mucosal pathogens, but has not been investigated in detail for Moraxella catarrhalis, a major cause of human respiratory tract infections. We investigated the role of outer membrane protein (OMP) UspA1 and lipooligosaccharide (LOS) in M. catarrhalis invasion into epithelial cells. An isogenic mutant of strain O35E, which lacked expression of the UspA1 adhesin, demonstrated not only severely impaired adherence (86%) to but also reduced invasion (77%) into Chang conjunctival cells in comparison with the wild-type strain. The isogenic, LOS-deficient mutant strain O35E.lpxA was attenuated in adherence (93%) and its capacity to invade was severely reduced (95%), but not abolished. Inhibition assays using sucrose and cytochalasin D, respectively, demonstrated that clathrin and actin polymerization contribute to internalization of M. catarrhalis by Chang cells. Furthermore, inhibition of UspA1-mediated binding to cell-associated fibronectin and alpha5beta1 integrin decreased invasion of M. catarrhalis strain O35E (72% and 41%, respectively). These data indicate that OMP UspA1 and LOS profoundly affect the capacity of M. catarrhalis to invade epithelial cells.