TABLE 6.

The heightened and lowered oral microbiota in COPD.

No	Studies	Outcomes	References
1	Characterization of periodontal microbiome from 55 COPD (n = 30 patient COPD with periodontitis (age 65.2 ± 7.4) and n- 25 patient COPD without periodontitis (age 65.6 ± 7.1) and 50 non-COPD (n = 25 patient with periodontitis (age 63.4 ± 7.0)) and n = 25 patient without periodontitis (age 64.8 ± 6.7) using 16S rRNA analysis gene metagenomic sequencing	- Patients with COPD exhibit a decrease in both the richness and diversity of bacteria in the periodontal tissues of individuals without periodontal disease - Three genera (Johnsonella, Campylobacter, and Oribacterium) and five species (J. ignava, P. canis, Fusobacterium simiae, Campylobacter showae, and Gemella cunicola) were found to be associated with COPD but not with periodontitis - The genera Johnsonella and J. ignava were linked to COPD but not to periodontitis. These genera are associated with oral squamous cell carcinoma - In this study, six genera related to periodontitis and eight species were identified in COPD patients. Genera Dysgonomonas, Desulfobulbus, and Catonella, as well as P. intermedia, P. endodontalis, D. wimpennyi, and C. morbi, were more abundant in COPD patients compared to non-COPD patients. Increasing of these microorganisms in periodontal tissue could be related to the development of COPD. - P. intermedia induces strong expression of antimicrobial peptides and IL-8, leading to migration of innate immune cells to the local infection site, resulting in an imbalance in local flora and inflammation - A decrease in the genera Oribacterium, Streptomyces, and Arcanobacterium was observed in the periodontal tissues of COPD patients. Understanding the microbial relationships and differences between COPD and periodontitis may provide a new strategy for the diagnosis, monitoring, and treatment of COPD.	Wu et al. (2017)
2	Investigated saliva microbiome of patients with COPD and periodontitis (n = 21 (age 60.36 ± 8.78)) compared with patients periodontitis (n = 36 (age 59.75 ± 8.00)), and healthy controls (n = 14 (age 60.24 ± 8.84)) using pyrosequencing of polymerase chain reaction-amplified 16s rRNA genes	- Indicates that the bacterial genera Rothia, Veillonella, and Actinomyces significantly increase during periodontitis and increase even more in patients with both periodontitis and COPD compared to healthy individuals - The bacterial genus Fusobacterium significantly decreases during periodontitis and decreases even more in patients with both periodontitis and COPD compared to healthy individuals	Lin et al. (2020)
3	Characterization oral microbiome from subgingival plaque and gingival crevicular fluid samples from healthy controls (n = 31 (age 25 (23–38)), patients with periodontitis (n = 24 (age 53.5 (47.25–61.25)), patients with COPD (n = 28 (age 61 (51,75–67.75)), and patients with both periodontitis and COPD (n = 29 (age 66 (60.5–72.5)) using16S rRNA gene sequencing	- According to LEfSe analysis in the GCF samples, the genera Mogibacterium increased in the group with COPD without periodontitis, while in patients with periodontitis and COPD, there was an increase in the genera Phocaeicola and Schwartzia - According to DESeq2 analysis, the genera Serratia decreased in COPD patients, while in patients with periodontitis and COPD, the genera Alloprevotella, Kingella, and Dialister experienced a decrease	Liu et al. (2023)