| Summary: | 碩士 === 國立成功大學 === 微生物暨免疫學研究所 === 96 === The prevalence of childhood allergy and asthma has increased during the past few decades in the developed world. The hygiene hypothesis suggests that the increase in the prevalence of allergic disease is related to reduced exposure to microbes at an early age as a result of improved hygiene and living conditions, vaccines, antibiotics therapy and smaller family sizes. Clinical trails have demonstrated that earlier introduction and continuous ingestion of Lactobacillus paracasei 33 (LP33) yogurts can improve the symptoms of allergic rhinitis but the mechanisms responsible for these benefits remain unclear. First, we used murine macrophage cell line RAW 264.7 and dendritic cell line DC2.4 to investigate the effects of LP33 on modulating cytokine productions via ELISA and RT-PCR analysis. LP33 induced IL-12, IL-10 and TGF-β productions in RAW 264.7 cells and IL-10 messenger RNA expression in DC2.4 cells in a does-dependent manners. Second, we sought to investigate the effects of Lactobacillus paracasei 33 yogurts in a mouse model of allergic airway inflammation. BALB/c mice were treated with two different doses of LP33, 3x106 CFU/700 μl and 9x106 CFU/700 μl, respectively, via gavaging needles for two weeks daily before Dermatophoides pteronyssinus (Der p) allergen sensitization and for another two weeks during sensitization and allergen challenge. The results showed that 9x106 CFU LP33 yogurts-treated mice exhibited decreased airway hyperresponsiveness and less influx of total leukocytes, monocytes and lymphocytes to the airway as compared to non-treated Der p-sensitized mice. The histological analysis also showed attenuated peribronchial inflammation and lung epithelial cells damage. Moreover, the Th1 cytokine IL-12 production in bronchoalveolar lavage fluid (BAL), Der p-specific IgG2a in sera, and IFN-γ production in Der p -stimulated splenocytes were significantly increased. In contrast, treatment of 3x106 CFU LP33 yogurts only elevated IFN-γ production in Der p-stimulated splenocytes and reduced the splenocyte proliferation activity. Taken together, our results showed that oral administration with Lactobacillus paracasei 33 yogurts can attenuate allergic airway inflammation by enhancing Th1 immune response.
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