Objective: Chronic obstructive pulmonary disease (COPD) is a major cause of global illness and death, most commonly caused by cigarette smoke. The mechanisms of pathogenesis remain poorly understood, limiting the development of effective therapies. The gastrointestinal microbiome has been implicated in chronic lung diseases via the gut-lung axis, but its role is unclear. Design: Using an in vivo mouse model of cigarette smoke (CS)-induced COPD and faecal microbial transfer (FMT), we characterised the faecal microbiota using metagenomics, proteomics and metabolomics. Findings were correlated with airway and systemic inflammation, lung and gut histopathology and lung function. Complex carbohydrates were assessed in mice using a high resistant starch diet, and in 16 patients with COPD using a randomised, double-blind, placebo-controlled pilot study of inulin supplementation. Results: FMT alleviated hallmark features of COPD (inflammation, alveolar destruction, impaired lung function), gastrointestinal pathology and systemic immune changes. Protective effects were additive to smoking cessation, and transfer of CS-associated microbiota after antibiotic-induced microbiome depletion was sufficient to increase lung inflammation while suppressing colonic immunity in the absence of CS exposure. Disease features correlated with the relative abundance of Muribaculaceae, Desulfovibrionaceae and Lachnospiraceae family members. Proteomics and metabolomics identified downregulation of glucose and starch metabolism in CS-associated microbiota, and supplementation of mice or human patients with complex carbohydrates improved disease outcomes. Conclusion: The gut microbiome contributes to COPD pathogenesis and can be targeted therapeutically.

Bifidobacterium are prominent gut commensals that produce the short-chain fatty acid (SCFA) acetate, and they are often used as probiotics. Connections between the gut and the lung, termed the gut–lung axis, are regulated by the microbiome. The gut–lung axis is increasingly implicated in cigarette smoke-induced diseases, and cigarette smoke exposure has been associated with depletion of Bifidobacterium species. In this study, we assessed the impact of acetate-producing Bifidobacterium longum subsp. longum (WT) and a mutant strain with an impaired acetate production capacity (MUT) on cigarette smoke-induced inflammation. The mice were treated with WT or MUT B. longum subsp. longum and exposed to cigarette smoke for 8 weeks before assessments of lung inflammation, lung tissue gene expression and cecal SCFAs were performed. Both strains of B. longum subsp. longum reduced lung inflammation, inflammatory cytokine expression and adhesion factor expression and alleviated cigarette smoke-induced depletion in caecum butyrate. Thus, the probiotic administration of B. longum subsp. longum, irrespective of its acetate-producing capacity, alleviated cigarette smoke-induced inflammation and the depletion of cecal butyrate levels.

This randomised controlled trial examined the effect of a 4-week, high-dose (Lf-High, 600 mg/d) or low-dose (Lf-Low, 200 mg/d) oral lactoferrin (Lf) intervention v . placebo on immune cell responses to respiratory virus, immune cell subsets and systemic inflammation. In healthy older adults ( n 103, ≥50 years old), ex vivo cytokine release of interferon (IFN)-α2, IFN-γ, IL-6 and TNF-α from rhinovirus A-16 (RV-16) or influenza A virus (H1N1) stimulated peripheral blood mononuclear cells, circulating immune cell subsets, and plasma IL-6, C-reactive protein (CRP) and TNF-α were assessed. Ninety-seven participants completed the 4-week intervention (Lf-High n 32, Lf-Low n 31, placebo n 34, withdrawals n 6). There was no difference in RV-16 or H1N1-induced IFN-γ release between groups. RV-16-induced IL-6 was lower in Lf-High v . placebo ( P = 0·001), and RV-16-induced IFN-α2 was higher in Lf-High v . Lf-Low ( P = 0·04). Lf-High increased total T cells ( P = 0·03) and CD4 ⁺ T cells ( P = 0·03) v . placebo. Lf-Low reduced neutrophil ( P = 0·04), natural killer cell ( P = 0·045), activated CD8 ⁺ T cell ( P = 0·03) and γδ T cell ( P = 0·03) frequency v . placebo. Plasma IL-6 ( P = 0·004) and CRP ( P = 0·03) were lower following Lf-High v . Lf-Low, but not placebo. Both high- and low-dose Lf altered ex vivo immune cell responses after 4 weeks. High-dose increased T-cell subsets, promoting adaptive immunity, and reduced systemic inflammation, while low-dose reduced proinflammatory and cytotoxic immune cells. High- and low-dose Lf supplements may have immunoceutical benefits in older adults.

Increasing evidence suggests that acquired dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel occurs as a result of cigarette smoke exposure in Chronic obstructive pulmonary disease (COPD). CFTR-targeted therapies were developed for the treatment of genetic CFTR defects in cystic fibrosis, but they have not demonstrated consistent clinical efficacy in small trials of patients with COPD. Here, we aimed to characterise CFTR activity, other ion channels, and differentiation to cilia in primary bronchial epithelial cells (pBECs) from COPD donors, compare to healthy controls, and to determine the extent to which CFTR dysfunction can be rescued by clinically relevant CFTR modulators. Conditionally reprogrammed (CR) air-liquid interface (ALI) cultures of pBECs from healthy controls (n = 7) and COPD donors (n = 7) were comprehensively assessed for transepithelial electrical resistance, immunofluorescence, cilia activity, ion channel function and expression of cell markers at transcript level. COPD cultures exhibited reduced active area of ciliated cells, accompanied by significantly decreased forskolin/IBMX stimulated CFTR-mediated Cl- transport and ATP induced calcium activated chloride currents compared to healthy controls cultures, despite preserved CFTR mRNA expression. Treatment with CFTR potentiators (VX-770, GLPG1837 and Icenticaftor) resulted in modest and highly variable functional responses, with no statistically significant improvement compared with vehicle-treated control. Notably, CFTR function did not correlate with cumulative smoking exposure (pack-years), indicating that smoking burden alone does not predict the extent of acquired CFTR dysfunction. Collectively, these findings demonstrate that COPD airway epithelium exhibits intrinsic defects in ion transport and mucociliary differentiation consistent with acquired CFTR dysfunction phenotype but this is not readily reversible with the tested CFTR modulators. These results highlight fundamental differences between genetic and acquired CFTR dysfunction and underscore the need for alternative or combinatorial therapeutic strategies targeting epithelial dysfunction in COPD.

Introduction: Primary air liquid interface (ALI) cultures of bronchial epithelial cells are used extensively to model airway responses. A recent advance is the development of conditional reprogramming that enhances proliferative capability. Several different media and protocols are utilized, yet even subtle differences may influence cellular responses. We compared the morphology and functional responses, including innate immune responses to rhinovirus infection in conditionally reprogrammed primary bronchial epithelial cells (pBECs) differentiated using two commonly used culture media. Methods: pBECs from healthy participants (n = 5) were CR using γ-irradiated 3T3 fibroblasts and Rho Kinase inhibitor. CRpBECs were differentiated at ALI in either PneumaCult™ (PN-ALI) or Bronchial Epithelial Growth Medium (BEGM)-based differentiation media (BEBM:DMEM, 50:50, Lonza™) - (AB-ALI) for 28 days. Transepithelial electrical resistance (TEER), immunofluorescence, histology, cilia activity, ion channel function, and expression of cell markers were analyzed. Viral load was assessed by RT-qPCR and anti-viral factors quantified by Legendplex following Rhinovirus-A1b (RVA1b) infection. Results: CRpBECs differentiated in PneumaCult™ were smaller and had a lower TEER and cilia beat frequency (CBF) compared to BEGM media. PneumaCult™ media cultures exhibited significantly increased FOXJ1 expression, more ciliated cells with a larger active area, increased intracellular mucins, and increased calcium-activated chloride channel current. However, there were no significant changes in viral RNA or host antiviral responses. Conclusion: There are distinct structural and functional differences in CRpBECs cultured in the two commonly used ALI differentiation media. Such factors need to be taken into consideration when designing and comparing CRpBECs ALI experiments.