Faculty Bibliography

Objective: To characterize the gut microbiota and host gene interactions in Reactive Arthritis (ReA) and postinfectious SpA. Methods: 32 patients with ReA and 32 controls with preceding Gastrointestinal (GI) and/or Genitourinary (GU) infections that did not develop arthritiswere prospectively recruited in Guatemala, a highly prevalent geographic region for this disease. Clinical variables, HLA status and 16S ribosomal RNA gene sequencing of intestinal microbiota were analysed. Results: Subjects with ReA showed no significant differences from controls in gut bacterial richness, alpha or beta diversity. However there was a higher abundance of Erwinia and Pseudomonas, and increased prevalence of typical enteropathogens associated with ReA. In Fact, at least one enteropathogen was present in 71.9% of ReA subjects vs 46.8% of controls (p<0.05). Subjects with ultrasound evidence of enthesitiswere enriched with Campylobacter,while subjects with Uveitis and radiographic sacroiliitis were enriched with Erwinia and unclassified Ruminococcaceae, respectively. Both were enriched in Dialister (log LDA>2). Host genetics, particularly HLA-A24 were associated with differences in gut microbiota diversity irrespective of disease status. We identified several co-occurring taxa that were also predictive of HLA-A24 status, including Ruminococcaceae-Rikenellaceae-Coriobacteriacea and Prevotellaceaeunclassified Sphingobacteriales-Elusimicrobiaceae. Conclusion: This is the first culture-independent study characterizing the gut microbial community of ReA. Although bacterial factors correlated with disease presence and clinical features of ReA, host genetics also appeared to be a major independent driver of intestinal community composition. Understanding of these gut microbiota host-genetic relationships may further clarify the pathogenesis of ReA and related Spondyloarthritis

Changes in lung microbiota associated with smoking might contribute to the development of acute respiratory distress syndrome in subjects with blunt trauma.

OBJECTIVE: Reactive arthritis (ReA) is an inflammatory disorder occurring several weeks after gastrointestinal or genitourinary infections. HLA-B27 positivity is considered a risk factor, though not necessarily predictive of disease incidence. Among non-genetic factors, the intestinal microbiome may play a role in disease susceptibility. The objective of this study was to characterize the gut microbiota and host gene interactions in ReA and post-infectious spondyloarthritis. METHODS: Adult peripheral spondyloarthritis and control subjects with preceding infections that did not develop arthritis were prospectively recruited from a highly prevalent geographic region. Clinical variables, HLA status, and 16S rRNA gene sequencing of intestinal microbiota were analyzed. RESULTS: ReA subjects showed no significant differences from controls in gut bacterial richness or diversity. However, there was a significantly higher abundance of Erwinia and Pseudomonas, and increased prevalence of typical enteropathogens associated with ReA. Subjects with ultrasound evidence of enthesitis were enriched in Campylobacter, while subjects with uveitis and radiographic sacroiliitis were respectively enriched in Erwinia and unclassified Ruminococcaceae, and both enriched in Dialister. Host genetics, particularly HLA-A24, were associated with differences in gut microbiota diversity irrespective of disease status. We determined several co-occurring taxa that were also predictive of HLA-A24 status. CONCLUSION: This is the first culture-independent study characterizing the gut microbial community of post-infectious arthritis. Although bacterial factors correlated with disease presence and clinical features of ReA, host genetics also appeared to be a major independent driver of intestinal community composition. Understanding of these gut microbiota host-genetic relationships may further clarify the pathogenesis of post-infectious spondyloarthropathies.

The use of culture-independent techniques has allowed us to appreciate that the upper and lower respiratory tract contain a diverse community of microbes in health and disease. Research has only recently explored the effects of the microbiome on the host immune response. The exposure of the human body to the bacterial environment is an important factor for immunological development; thus, the interaction between the microbiome and its host is critical to understanding the pathogenesis of disease. In this article, we discuss the mechanisms that determine the composition of the airway microbiome and its effects on the host immune response. With the use of ecological principles, we have learned how the lower airways constitute a unique niche subjected to frequent microbial migration (e.g., through aspiration) and constant immunological pressure. The discussion will focus on the possible inflammatory pathways that are up- and downregulated when the immune system is challenged by dysbiosis. Identification of potential markers and microbial targets to address the modulation of inflammation in early disease, when changes may have the most effect, will be critical for future therapies.

PURPOSE: Reflux esophagitis (ReE) and eosinophilic esophagitis (EoE) are associated with the presence of eosinophils in esophageal mucosa and are considered to be important co-morbid factors for chronic cough and asthma in adults. We hypothesize that esophageal eosinophils related to ReE and EoE are present in children with refractory asthma and chronic cough and correlate with airway eosinophilia. METHODS: We performed a retrospective analysis of medical records of children who underwent "triple endoscopy" (sleep laryngoscopy, bronchoscopy with bronchoalveolar lavage (BAL) and endobronchial biopsy (EBB), and esophagogastroduodenoscopy with esophageal biopsy (EsB)) at our Aerodigestive Center for evaluation of refractory asthma and cough. Inclusion criteriawere cough for 8 weeks or more with no response to trial of antibiotics and systemic/inhaled corticosteroids (ICS), poor control of asthma symptoms, and/or airflowlimitations and air trapping despite use ICS or ICS/long-acting beta-agonist combination. Children with known cystic fibrosis, primary ciliary dyskinesia and aspiration into airway were excluded. RESULTS: Thirty-two children (22 males) met inclusion criteria. Nineteen had refractory asthma and 13 had chronic cough. There were no significant complications recorded after procedures including EBB. Eosinophils (>1%) were present in BAL of 8 (25%) children. EBB showed eosinophils in 17 (53%) children. There were a total of 19 children with eosinophils isolated from the airway (either BAL or EBB), 4 (21%) had them in BAL alone, 8 (42%) in EBB only, and 7 (37%) in both BAL and EBB. EoE was diagnosed in 6 children (19%) and ReE in 13 (41%). EsB revealed esophageal eosinophils in 47% of children. Presence of eosinophils in EsB was related to presence of eosinophils in EBB chi² (1, N = 32), p = 0.026, but not BAL (p=0.89). CONCLUSIONS: ReE and EoE with esophageal eosinophils was present in 47% of children with refractory asthma and chronic cough. There is a significant relationship between airway and esophageal eosinophils, which becomes evident only when EBB is performed for detection of airway eosinophils. Further research is required for understanding the association of airway and esophageal eosinophilia in the development and management of refractory asthma and cough

Antibiotic therapy against non-tuberculous mycobacteria (NTM) is prolonged and can be associated with toxicity. We sought to evaluate whether chest physical therapy (PT) was associated with clinical improvement in patients with NTM not receiving anti-mycobacterial pharmacotherapy. A retrospective review of 77 subjects that were followed from June 2006 to September 2014 was performed. Baseline time point was defined as the first positive sputum culture for NTM; symptoms, pulmonary function, and radiology reports were studied. Subjects were followed for up to 24 months and results analyzed at specified time points. Half of the subjects received chest PT at baseline. Cough improved at 12 (p = 0.001) and 24 months (p = 0.003) in the overall cohort when compared with baseline, despite lack of NTM antibiotic treatment. Cough decreased at 6 (p = 0.01), 9 (p = 0.02), 12 (p = 0.02) and 24 months (p = 0.002) in subjects that received chest PT. Sputum production also improved at 24 months in the overall cohort (p = 0.01). There was an increase in the percent change of total lung capacity in subjects that received chest PT (p = 0.005). Select patients with NTM may have clinical improvement with chest PT, without being subjected to prolonged antibiotic therapy. Future studies are warranted to prospectively evaluate outcomes in the setting of non-pharmacologic treatment and aid with the decision of antibiotic initiation.

Therapies targeting inflammation reveal inconsistent results in idiopathic pulmonary fibrosis (IPF). Aerosolised interferon (IFN)-gamma has been proposed as a novel therapy. Changes in the host airway microbiome are associated with the inflammatory milieu and may be associated with disease progression. Here, we evaluate whether treatment with aerosolised IFN-gamma in IPF impacts either the lower airway microbiome or the host immune phenotype. Patients with IPF who enrolled in an aerosolised IFN-gamma trial underwent bronchoscopy at baseline and after 6 months. 16S rRNA sequencing of bronchoalveolar lavage fluid (BALF) was used to evaluate the lung microbiome. Biomarkers were measured by Luminex assay in plasma, BALF and BAL cell supernatant. The compPLS framework was used to evaluate associations between taxa and biomarkers. IFN-gamma treatment did not change alpha or beta diversity of the lung microbiome and few taxonomic changes occurred. While none of the biomarkers changed in plasma, there was an increase in IFN-gamma and a decrease in Fit-3 ligand, IFN-alpha2 and interleukin-5 in BAL cell supernatant, and a decrease in tumour necrosis factor-beta in BALF. Multiple correlations between microbial taxa common to the oral mucosa and host inflammatory biomarkers were found. These data suggest that the lung microbiome is independently associated with the host immune tone and may have a potential mechanistic role in IPF.