Effect of Omega-3 Fatty Acids on TH1/TH2 Polarization in Individuals with High Exposure To Particulate Matter ≤ 2.5 μm (PM2.5): A Randomized, Double-Blind, Placebo-Controlled Clinical Study

Abstract Background: Long-term exposure to high concentrations of PM2.5 may cause immune system dysfunction and damage to the respiratory and cardiovascular systems. PM2.5 may cause CD4 + T helper cells to polarize toward TH1 or TH2 cell types, which may be associated with the onset and progression of many human diseases. Recent studies have shown that omega-3 fatty acids can regulate human immune function and reduce physiological damage caused by air pollution; however, only limited research has examined the therapeutic effects of omega-3 fatty acids on subjects with high exposure to PM2.5 in mass transit systems such as subways.Methods: This study was designed as a prospective, randomized, double-blinded (to participants and researchers), placebo-controlled trial. The research plan is to recruit 120 qualified volunteers in the Chengdu Metro Station. All participants will receive omega-3 fatty acids or placebo for 8 weeks. The primary outcomes will be changes in the TH1/TH2 cell polarization index and changes in serum cytokine concentrations. Secondary outcomes will be changes in early indicators of atherosclerosis, pulmonary function, COOP/WONCA charts, and scores on the Short Form 36 Health Survey for quality of life. Results will be analyzed to evaluate differences in clinical efficacy between the two groups. A six-month follow-up period will be used to assess the long-term value of omega-3 fatty acids for respiratory and cardiovascular disease end-points.Disscussion: We will explore the characteristics of TH1/TH2 cell polarization index in a population with high exposure to PM2.5. Omega-3 fatty acids and placebo will be compared in many ways to test the effect on people exposed to PM2.5 subway stations. This study is expected to provide reliable evidence to support the promotion of omega-3 fatty acids in clinical practice to protect individuals who are highly exposed to PM2.5.Trial registration: Chinese Clinical Trial Registry (ChiCTR2000038065). Registered on September 9, 2020.