Investigation on the Pathological Mechanism of Frequent Exacerbators With Chronic Obstructive Pulmonary Disease Based on the Characteristics of Respiratory Flora

Abstract

Chronic obstructive pulmonary disease (COPD) is a common obstructive respiratory disease characterized by persistent respiratory symptoms and limited airflow due to airway obstruction. The present study investigates the distribution characteristics of respiratory tract flora in both frequent and infrequent exacerbators of COPD. The 16S sequencing technique was adopted to differentiate the inherent differences of respiratory tract flora between frequent exacerbators and infrequent exacerbators. Additionally, cell counting kit 8 (CCK8), lactate dehydrogenase (LDH) test, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and western blot were carried out in human bronchial epithelial cells cultured in vitro and the regulatory effects of differential flora were verified. The results revealed that the observed species index, Chao1 index, and the ACE estimator of COPD frequent exacerbators were markedly higher than those of COPD infrequent exacerbators. The top five strains of COPD frequent exacerbators included g_Streptococcus (15.565%), g_Prevotella (10.683%), g_Veillonella (6.980%), g_Haemophilus (5.601%), and g_Neisseria (4.631%). Veillonella parvula generated obvious cytotoxicity and substantially reduced the activity of human bronchial epithelial cells (p < 0.01). Furthermore, the results of flow cytometry indicated that the proportion of human bronchial epithelial cells in both the S phase and G2 phase decreased following Veillonella parvula treatment indicated that Veillonella parvula inhibited cell proliferation. Meanwhile, being treated using Veillonella parvula, the expressions of interleukin-1 (IL-1), IL-6, Tumor Necrosis Factor α (TNF-α), and p-nuclear factor kappa B (NF-κB) of the cells were increased markedly (p < 0.01). Taken together, the current research demonstrated that the relative abundance of Veillonella in COPD frequent exacerbators was higher than that of infrequent exacerbators. Veillonella parvula activated the inflammatory pathway, ultimately destroyed the cell viability, and greatly impaired the activity of human bronchial epithelial cells, thereby inhibiting cell proliferation.

Veillonella parvula: An update from a stomatological point of view

“…It has been documented that Veillonella parvula can cause spondylitis [1] , osteomyelitis [3] , and epidural abscesses in immunocompromised patients [13] . This bacterium has been seen in children with pneumonia [14] and acromioclavicular septic arthritis [15] , reduces the activity of bronchial epithelia in obstructive pulmonary disease [16,17] and produces nasal sepsis [18] . It has also been found at a high level in patients with COVID 19 [19] , as well as with early childhood caries [20] , lung cancer [21] , nasopharyngeal carcinoma [22] , and epithelial squamous cell carcinoma [23] .…”

Detecting and quantifying Veillonella by real-time quantitative PCR and droplet digital PCR

“…However, many studies have suggested that elevated abundance of Veillonella can cause a range of diseases. For example, V. parvula has been detected in blood, bone, the oral cavity, urinary tract, heart valves, cerebrospinal fluid, respiratory tract, and gastrointestinal tract, causing multiple diseases including bacteremia, intervertebral discitis, dental caries, urinary tract infection, endocarditis, meningitis, and inflammatory bowel disease (IBD) (Chang et al 2023;Rojas-Tapias et al 2022;Li et al 2017;Bhatti and Frank 2000;Ke et al 2022;Berenger et al 2015;Chen et al 2021;Washio et al 2014). Under normal conditions, Veillonella is not present in the blood, bones, heart valves, or cerebrospinal fluid, and if detected at these sites, it is considered a potential pathogen.…”