Genomic attributes of airway commensal bacteria and mucosa

Microbial communities at the airway mucosal barrier are conserved and highly ordered, in likelihood reflecting co-evolution with human host factors. Freed of selection to digest nutrients, the airway microbiome underpins cognate management of mucosal immunity and pathogen resistance. We show here the initial results of systematic culture and whole-genome sequencing of the thoracic airway bacteria, identifying 52 novel species amongst 126 organisms that constitute 75% of commensals typically present in heathy individuals. Clinically relevant genes encode antimicrobial synthesis, adhesion and biofilm formation, immune modulation, iron utilisation, nitrous oxide (NO) metabolism and sphingolipid signalling. Using whole-genome content we identify dysbiotic features that may influence asthma and chronic obstructive pulmonary disease. We match isolate gene content to transcripts and metabolites expressed late in airway epithelial differentiation, identifying pathways to sustain host interactions with microbiota. Our results provide a systematic basis for decrypting interactions between commensals, pathogens, and mucosa in lung diseases of global significance.

Mepolizumab for the treatment of eosinophilic granulomatosis with polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare but potentially life-threatening antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis which affects, to varying degrees, the lungs, paranasal sinuses, heart, kidneys, skin and peripheral nervous system. It is strongly associated with asthma. Peripheral eosinophilia is a defining feature of EGPA and eosinophilic inflammation is often observed in biopsies of affected tissues. Acute and chronic management focuses on the control of inflammation with systemic corticosteroids and other immunosuppressants, all of which carry a significant burden of adverse effects. The development of monoclonal antibody therapies against interleukin-5 (IL-5), the major driver of eosinophilic inflammation, has therefore garnered significant interest among clinicians treating EGPA, who are hopeful that the targeted antieosinophilic effects of such drugs observed in large-scale asthma studies may be replicated in EGPA cohorts. In this review we discuss the features of EGPA, including the current understanding of the eosinophil's role in its pathogenesis. We also review the evidence to date regarding the efficacy of mepolizumab (an anti-IL-5 monoclonal antibody) in severe eosinophilic asthma and the smaller evidence base regarding its efficacy in EGPA, an indication for which it recently received U.S. Food and Drug Administration approval. The possible limitations of mepolizumab in EGPA management are also considered and suggestions put forward regarding the issues that further studies should seek to explore.

The Biology of Eosinophils and Their Role in Asthma

This review will describe the structure and function of the eosinophil. The roles of several relevant cell surface molecules and receptors will be discussed. We will also explore the systemic and local processes triggering eosinophil differentiation, maturation, and migration to the lungs in asthma, as well as the cytokine-mediated pathways that result in eosinophil activation and degranulation, i.e., the release of multiple pro-inflammatory substances from eosinophil-specific granules, including cationic proteins, cytokines, chemokines growth factors, and enzymes. We will discuss the current understanding of the roles that eosinophils play in key asthma processes such as airway hyperresponsiveness, mucus hypersecretion, and airway remodeling, in addition to the evidence relating to eosinophil–pathogen interactions within the lungs.