Pears are ancient functional foods for modern times. Particularly, Korean pears (Pyrus pyrifolia cv.) have been used as folk medicine for respiratory diseases and have strong potential for the treatment of hazardous aerosol-related diseases. Thus, the effects of pear ethanol extracts on air pollution-related respiratory hypersensitivity were studied by toxicokinetics, pro-inflammatory cytokines, and microbiomics in preclinical and randomized double-blind clinical studies. The mild-asthma subjects, who lived in the same city, Seoul, Korea, were separated into the placebo and the treatment (pear extracts, as brix 55; arbutin 5.01 mg and chlorogenic acid 0.18 mg/3 mL per day) groups for 4 weeks (n = 20). As results, there were positive associations between urinary 2-naphthol (NT) or 1-hydroxypyrene (OHP), exposure biomarkers for polyaromatic hydrocarbons in PM2.5, and pro-inflammatory cytokines, interleukin (IL)-4 or IgE, respectively, in the human subjects. The pear extracts somewhat reduced 2-NT and 1-OHP levels. The proportions of fiber-degrading bacteria that stimulate growth of beneficial microflora for immune defense, that is, Bifidobacterium and Eubacterium, were significantly higher in the pear consuming group than in the placebo group. Moreover, pro-inflammatory cytokines, including IgE, IL-4, IL-5, and IL-13, were significantly suppressed by the pear extracts in the preclinical tests of the ovalbumin-induced asthma mice. Thus, we suggest that air pollution-related respiratory hypersensitivity can be alleviated by Korean pear extracts by modulation of microbiome and immunocytokines.
Keywords: Korean pears; PM2.5; cytokine; immune modulation; microbiome.