Faculty Bibliography

INTRODUCTION: Azithromycin (AZM) reduces pulmonary inflammation and exacerbations in patients with COPD having emphysema. The antimicrobial effects of AZM on the lower airway microbiome are not known and may contribute to its beneficial effects. Here we tested whether AZM treatment affects the lung microbiome and bacterial metabolites that might contribute to changes in levels of inflammatory cytokines in the airways. METHODS: 20 smokers (current or ex-smokers) with emphysema were randomised to receive AZM 250 mg or placebo daily for 8 weeks. Bronchoalveolar lavage (BAL) was performed at baseline and after treatment. Measurements performed in acellular BAL fluid included 16S rRNA gene sequences and quantity; 39 cytokines, chemokines and growth factors and 119 identified metabolites. The response to lipopolysaccharide (LPS) by alveolar macrophages after ex-vivo treatment with AZM or bacterial metabolites was assessed. RESULTS: Compared with placebo, AZM did not alter bacterial burden but reduced alpha-diversity, decreasing 11 low abundance taxa, none of which are classical pulmonary pathogens. Compared with placebo, AZM treatment led to reduced in-vivo levels of chemokine (C-X-C) ligand 1 (CXCL1), tumour necrosis factor (TNF)-alpha, interleukin (IL)-13 and IL-12p40 in BAL, but increased bacterial metabolites including glycolic acid, indol-3-acetate and linoleic acid. Glycolic acid and indol-3-acetate, but not AZM, blunted ex-vivo LPS-induced alveolar macrophage generation of CXCL1, TNF-alpha, IL-13 and IL-12p40. CONCLUSION: AZM treatment altered both lung microbiota and metabolome, affecting anti-inflammatory bacterial metabolites that may contribute to its therapeutic effects. TRIAL REGISTRATION NUMBER: NCT02557958.

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.

BACKGROUND: Airway abnormalities and lung tissue citrullination are found in both rheumatoid arthritis (RA) patients and individuals at-risk for disease development. This suggests the possibility that the lung could be a site of autoimmunity generation in RA, perhaps in response to microbiota changes. We therefore sought to test whether the RA lung microbiome contains distinct taxonomic features associated with local and/or systemic autoimmunity. METHODS: 16S rRNA gene high-throughput sequencing was utilized to compare the bacterial community composition of bronchoalveolar lavage fluid (BAL) in patients with early, disease-modifying anti-rheumatic drugs (DMARD)-naive RA, patients with lung sarcoidosis, and healthy control subjects. Samples were further assessed for the presence and levels of anti-citrullinated peptide antibodies (including fine specificities) in both BAL and serum. RESULTS: The BAL microbiota of RA patients was significantly less diverse and abundant when compared to healthy controls, but similar to sarcoidosis patients. This distal airway dysbiosis was attributed to the reduced presence of several genus (i.e., Actynomyces and Burkhordelia) as well as reported periodontopathic taxa, including Treponema, Prevotella, and Porphyromonas. While multiple clades correlated with local and systemic levels of autoantibodies, the genus Pseudonocardia and various related OTUs were the only taxa overrepresented in RA BAL and correlated with higher disease activity and erosions. CONCLUSIONS: Distal airway dysbiosis is present in untreated early RA and similar to that detected in sarcoidosis lung inflammation. This community perturbation, which correlates with local and systemic autoimmune/inflammatory changes, may potentially drive initiation of RA in a proportion of cases.

Smoking induced inflammation leads to distal airway destruction. However, the relationship between distal airway dysfunction and inflammation remains unclear, particularly in smokers prior to the development of airway obstruction. Seven normal controls and 16 smokers without chronic obstructive pulmonary disease (COPD) were studied. Respiratory function was assessed using the forced oscillation technique (FOT). Abnormal FOT was defined as elevated resistance at 5 Hz (R5). Parameters reflecting distal lung function included frequency dependence of resistance (R5-20) and dynamic elastance (X5). Inflammation was quantified in concentrated bronchoalveolar lavage utilising cell count differential and cytokines expressed as concentration per mL epithelial lining fluid. All control subjects and seven smokers had normal R5. Nine smokers had elevated R5 with abnormal R5-20 and X5, indicating distal lung dysfunction. The presence of abnormal FOT was associated with two-fold higher lymphocyte and neutrophil counts (p<0.025) and with higher interleukin (IL)-8, eotaxin and fractalkine levels (p<0.01). Reactivity of R5-20 and X5 correlated with levels of IL-8, eotaxin, fractalkine, IL-12p70 and transforming growth factor-alpha (r>0.47, p<0.01). Distal airway dysfunction in smokers without COPD identifies the presence of distal lung inflammation that parallel reported observations in established COPD. These findings were not evident on routine pulmonary function testing and may allow the identification of smokers at risk of progression to COPD.

Background/Purpose: Psoriasis (PsO) is a chronic immune-mediated skin condition affecting ~3% of adults worldwide. Up to a third of PsO patients go on to develop psoriatic arthritis (PsA), a heterogeneous inflammatory arthritis characterized by concomitant bone erosion and osteoproliferation. Although multiple advances have been made in the pathogenesis and therapeutics of these disorders, it is currently not possible to predict which individuals will progress from PsO to PsA. The role of the microbiome as a potential trigger for autoimmunity and rheumatic disease has recently been implicated. The goal of this study was to characterize the cutaneous microbiota of patients with PsO and PsA (in both psoriatic plaques and unaffected skin) to determine if there are characteristic features related to disease phenotype. Methods: Skin swabs from subjects with PsO (n=29) and PsA (n=62) were collected from both psoriatic plaque lesions and contralateral unaffected skin. 16S rDNA was extracted per protocol (MoBio, USA) and amplicons targeting the hypervariable V4 region were sequenced using MiSeq (Illumina) to define the microbiota composition. The obtained 16S rRNA sequences were analyzed using the Quantitative Insights into Microbial Ecology (QIIME) pipeline. Taxonomic relative abundance was determined to compare their prevalence among different phenotypes using Kruskal-Wallis statistical analysis. Alpha diversity plots and weighted Unifrac analysis (beta diversity) of cutaneous bacterial communities were generated. False discovery rate analysis was applied to identify unique differentiating taxa. Results: Baseline characteristics were comparable in both groups. PsO samples had, on average, a similar number of operational taxonomic units as compared to PsA samples. Beta diversity plots did not demonstrate statistically distinct clustering of microbial communities between PsO and PsA subjects, PsO and PsA nonlesional skin, or PsO and PsA lesional skin. Staphylococcus and Corynebacterium were the most abundant genera across all samples. However, several genera were statistically more abundant in PsO compared to PsA lesions, including unclassified Bradyrhizobiaceae (p<0.0006), Rahnella (p<0.0006), unclassified Prevotellaceae (p<0.001), and Parvibaculum (p<0.002). Rothia was more abundant in PsA (p<0.02). Conclusion: Our results characterize, for the first time, the cutaneous microbial composition of individuals with PsO compared to those with PsA both in psoriatic lesions and unaffected skin. Although we did not find overall community differences among the various phenotypes, our preliminary observations point towards differences in specific genera, which are characteristically more abundant in PsO. Further in-depth analysis is required to better understand the significance of this dysbiotic process in PsA and whether it contributes to the pathogenesis of the psoriatic disease spectrum. Current efforts are devoted to incorporating healthy controls into our analysis, and analyzing the cutaneous microbiome (and metagenome) across multiple body sites, multiple visits, as well as pre- and post-immunosuppressive/biologic therapy