Exploring the Role of Gut-Lung Interactions in COPD Pathogenesis: A Comprehensive Review on Microbiota Characteristics and Inflammation Modulation

Chronic Obstr Pulm Dis. 2024 Apr 1. doi: 10.15326/jcopdf.2023.0442. Online ahead of print.

Abstract

Chronic obstructive pulmonary disease (COPD) is a paramount contributor to global morbidity and mortality. Over the past decade, the concept of the "gut-lung axis" has emerged, offering a lens through which to examine the intricate interplay between the host, microbiome, and respiratory diseases, including COPD. An expanding body of evidence underscores that the composition of both the gastrointestinal and respiratory microbiome deviates in COPD patients compared to healthy individuals, leading to distinct host immune responses and clinical manifestations. The objective of this review is to provide a concise overview of the role of both gut and respiratory microbiome plays in the development of COPD. This will be accomplished by compiling current literature on the microbiome profile in stable and exacerbated cases of COPD, as well as exploring the biological mechanisms through a discussion of relevant experiments conducted on murine models. Hallmark characteristics of the microbial profile in COPD encompass reduced Prevotella spp. in the respiratory microbiome, culminating in a loss of anti-inflammatory protection, and diminished Bacteroidetes in the gut microbiome, leading to a decrease in protective short-chain fatty acids (SCFAs). The proliferation of Proteobacteria, particularly Haemophilus spp., Moraxella spp. and Pseudomonas spp. contributes to COPD pathologies via recognition of proinflammatory lipopolysaccharide (LPS) via Toll-like receptors (TLRs). As a consequence, deteriorated pulmonary function, enhanced severity, increased onset of exacerbations and elevated mortality were observed.

Keywords: COPD; gut microbiota; gut-lung axis; inflammation; lung microbiota.