Abstract
BackgroundExtended exposure to high concentrations of PM2.5 changes the human microbiota profile, which in turn may increase morbidity and mortality due to respiratory system damage. A balanced microecosystem is crucial to human health, and certain health-related problems may be addressed by effective microecosystem regulation. Recent studies have confirmed that probiotics may reduce the incidence of respiratory diseases. However, few studies have investigated probiotic treatment outcomes in subjects exposed to high concentrations of PM2.5.MethodsThis study is designed as a prospective, randomized, participants- and assessor-blinded, placebo-controlled trial. One hundred and twenty eligible volunteers recruited from October 2019 to July 2020 in downtown Chengdu, China, will be treated with either probiotics or placebo over 4 consecutive weeks. The primary outcome will be 16SrRNA sequencing assay data from nasal and intestinal secretions. Secondary outcomes will be pulmonary function, score on a gastrointestinal symptom rating scale, COOP/WONCA charts, and the Short-Form Health Survey 36 for quality of life. Results will be analyzed to assess differences in clinical efficacy between groups. Six-month follow-up examinations will evaluate the long-term value of probiotics on cardiovascular and respiratory disease end-point events.DiscussionWe will explore the characteristics of nasal and intestinal microbiota in a population with high exposure to PM2.5. Probiotics and placebo interventions will be tested for efficacy in microbial balance regulation, effects on lung and physical functions, and quality of life improvement. This study is expected to provide reliable evidence to support the widespread promotion of probiotics in clinical practice for the protection of individuals with high exposure to PM2.5.Trial registrationChinese Clinical Trial Registry ChiCTR1900025469. Registered on 27 August 2019.
Highlights
Extended exposure to high concentrations of PM2.5 changes the human microbiota profile, which in turn may increase morbidity and mortality due to respiratory system damage
Several studies demonstrated that high-levels of PM2.5/PM10 were related to alterations in the human pharyngeal [21], nasal [22], and intestinal [23] microbiota composition
The microorganisms carried by PM2.5 induce the pro-inflammatory response of resident immune cells, increase intestinal permeability, and change the lumen environment of the intestine, leading to growth of specific microbial strains better suited for survival in an inflammatory environment
Summary
Extended exposure to high concentrations of PM2.5 changes the human microbiota profile, which in turn may increase morbidity and mortality due to respiratory system damage. PM2.5 may adsorb a variety of organic compounds, heavy metals, pathogenic microorganisms, and acid oxides and may enter the lower respiratory tract during respiratory movement, reaching the alveoli and possibly the blood circulation These characteristics implicate PM2.5 as a potential cause of the recent increase in respiratory disease incidence [5]. Numerous epidemiological studies have revealed that long-term exposure to PM2.5 pose great risks to human health Such as, the increase of PM2.5 concentration is closely correlated to the hospitalization rate and mortality associated with respiratory diseases [6,7,8,9]. The studies suggest that air pollution is one of the residual risk factors of CAD, and long-term exposure to fine particulate air pollution is associated with degree of coronary artery calcification, ischemic heart disease, and stroke mortality [13,14,15]. It has been reported that exposure to environmental fine particles can change the structure of nasal [26] and intestinal microbiota [27], so we choose nasal and intestinal microbiota as evaluation indicators
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