肺肠轴如何影响COPD？2024微生物组机制与临床证据解析

The respiratory and gastrointestinal mucosae both originate from the endoderm, and they share certain similarities in anatomical structure and physiological function, potentially interacting through microorganisms [35]. Based on this, modern medicine has proposed the concept of the "lung-gut" axis, which posits that symbiotic microbial communities participate in host nutritional, immune, and metabolic functions, influencing the occurrence and development of respiratory diseases [39,40]. The lungs and gut interact and regulate each other through the lymphatic circulation, blood circulation, and mucosal immune system, influenced by the balance of their respective microbiota, participating in local and systemic immune responses to achieve bidirectional regulation [41]. Studies have shown that chronic pulmonary diseases such as COPD and asthma often co-occur with chronic gastrointestinal diseases like inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS) [42]. Research indicates that approximately 50% of adult IBD patients and 33% of IBS patients have lung tissue involvement, such as inflammation or impaired lung function, with most patients having no history of acute or chronic respiratory diseases [43]. Additionally, patients with COPD are 2-3 times more likely to be diagnosed with IBD, and patients with asthma exhibit functional and structural changes in the intestinal mucosa. Patients with COPD also typically show increased gut permeability [24]. In terms of gut microbial composition, there are significant differences between the overall community compositions of COPD and healthy guts [44]. 16S rRNA gene sequencing results show that bacterial genera with increased abundance in COPD feces include Streptococcus and Rothia, which are common oral bacteria also found in the gut, originating from the Streptococcaceae family and the Enterobacteriaceae family, including Escherichia coli, Lactobacillus, and Enterobacter. Bacterial genera with decreased abundance in COPD include Bacteroides, Roseburia, and Lachnospira from the Lachnospiraceae family, as well as several unnamed genera from the Ruminococcaceae family. Furthermore, smoking is a major causative factor for COPD [45], and the gut microbiota varies with different smoking statuses. Smoking exerts a downregulating effect on Firmicutes and an upregulating effect on Bacteroidetes, changes that can be reversed after quitting smoking [46].