Kyoko Oh-Oka

University of Yamanashi, Kōhu, Yamanashi, Japan

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Publications (6)15.16 Total impact

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    ABSTRACT: Background: Maternal milk-borne transforming growth factor (TGF-β plays a potential role in the development of the mucosal immune system in infants. However, it remains unclear what factors determine TGF-β levels in breast milk. We hypothesized that microbial pressures during pregnancy might affect the expression levels of TGF-β in colostrum.
    Asian Pacific journal of allergy and immunology / launched by the Allergy and Immunology Society of Thailand 06/2014; 32(2):178-184. · 0.79 Impact Factor
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    Allergology International 03/2014;
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    ABSTRACT: The aryl hydrocarbon receptor (AhR) recognizes environmental xenobiotics and is originally thought to be involved in the metabolism (detoxification) of the substances. Recently, AhR is highlighted as an important regulator of inflammation. Notably, accumulating evidence suggests that activation of the AhR suppresses inflammatory bowel diseases (IBDs). Therefore, non-toxic AhR activators become attractive drug candidates for IBD. This study identified 1,4-dihydroxy-2-naphthoic acid (DHNA), a precursor of menaquinone (vitamin K2) abundantly produced by Propionibacterium freudenreichii ET-3 isolated from Swiss-type cheese, as an AhR activator. DHNA activated the AhR pathway in human intestinal epithelial cell line Caco2 cells and in the mouse intestine. Oral treatment of mice with DHNA induced anti-microbial proteins RegIIIβ and γ in the intestine, altered intestinal microbial flora and inhibited dextran sodium sulfate (DSS)-induced colitis, which recapitulated the phenotypes of AhR activation in the gut. As DHNA is commercially available in Japan as a prebiotic supplement without severe adverse effects, DHNA or its derivatives might become a promising drug candidate for IBD via AhR activation. The results also implicate that intestinal AhR might act not only as a sensor for xenobiotics in diet and water but also for commensal bacterial activity because DHNA is a precursor of vitamin K2 produced by vitamin K2-synthesizing commensal bacteria as well as propionic bacteria. Hence, DHNA might be a key bacterial metabolite in the host-microbe interaction to maintain intestinal microbial ecosystem.Immunology and Cell Biology advance online publication, 11 February 2014; doi:10.1038/icb.2014.2.
    Immunology and Cell Biology 02/2014; · 3.93 Impact Factor
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    ABSTRACT: The circadian clock drives daily rhythms in behavior and physiology. A recent study suggests that intestinal permeability is also under control of the circadian clock. However, the precise mechanisms remain largely unknown. Because intestinal permeability depends on tight junction (TJ) that regulates the epithelial paracellular pathway, this study investigated whether the circadian clock regulates the expression levels of TJ proteins in the intestine.
    PLoS ONE 01/2014; 9(5):e98016. · 3.53 Impact Factor
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    ABSTRACT: Resveratrol is a bioactive polyphenol enriched in red wine that exhibits many beneficial health effects via multiple mechanisms. However, it is unclear whether resveratrol is beneficial for the prevention of food allergy. This study investigated whether resveratrol inhibited the development of food allergy by using a mouse model of the disease. Mice fed standard diet or standard diet plus resveratrol were sensitized by intragastric administration of ovalbumin (OVA) and mucosal adjuvant cholera toxin (CT). Several manifestations of food allergy were then compared between the mice. The effects of resveratrol on T cells or dendritic cells were also examined by using splenocytes from OVA-specific T cell-receptor (TCR) transgenic DO11.10 mice or mouse bone marrow-derived dendritic cells (BMDCs) in vitro. We found that mice fed resveratrol showed reduced OVA-specific serum IgE production, anaphylactic reaction, and OVA-induced IL-13 and IFN-ã production from the mesenteric lymph nodes (MLNs) and spleens in comparison to the control mice, following oral sensitization with OVA plus CT. In addition, resveratrol inhibited OVA plus CT-induced IL-4, IL-13, and IFN-ã production in splenocytes from DO11.10 mice associated with inhibition of GATA-3 and T-bet expression. Furthermore, resveratrol suppressed the OVA plus CT-induced CD25 expression and IL-2 production in DO11.10 mice-splenocytes in association with decreases in CD80 and CD86 expression levels. Finally, resveratrol suppressed CT-induced cAMP elevation in association with decreases in CD80 and CD86 expression levels in BMDCs. Ingestion of resveratrol prevented the development of a food allergy model in mice. Given the in vitro findings, resveratrol might do so by inhibiting DC maturation and subsequent early T cell activation and differentiation via downregulation of CT-induced cAMP activation in mice. These results suggest that resveratrol may have potential for prophylaxis against food allergy.
    PLoS ONE 01/2012; 7(9):e44338. · 3.53 Impact Factor
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    ABSTRACT: Cytokines in breast milk may play crucial roles in the beneficial effects of breastfeeding in protecting against allergic and infectious diseases in infants. In particular, breast milk-borne transforming growth factor-beta (TGF-β) has an important potential role in developing the mucosal immune system in infants. However, little is known about what factors influence TGF-β expression in human milk. We investigated whether the behavioral and psychosocial characteristics of mothers affect breast milk TGF-β levels. We conducted a survey of all 139 mothers who were lactating between February and October 2010 in Koshu City, Japan. Participants completed a questionnaire and provided breast milk at the health checkups for their 3-month-old child (N = 129, 93%). Breast milk was assayed for total TGF-β2 levels by ELISA. We took an exploratory approach based on linear and ordered logistic regressions to model TGF-β2 concentrations with their multiple potential determinants. Mothers with depression or poor self-rated health had higher TGF-β2 concentrations than mothers without depression (odds ratio for a higher TGF-β2 quartile: 3.11, 95% confidence intervals: 1.03-9.37) or those reporting better health (odds ratio: 2.34, 1.21-4.55). Smoking, drinking alcohol, probiotics supplementation, social support, and maternal history of allergic diseases were not associated with milk TGF-β2 levels. Milk gathered between August and October or later in the afternoon (3-4 pm vs. 12-2 pm) contained less TGF-β2. Depression, as the consequence of psychosocial stress, may be a strong determinant of TGF-β levels in breast milk. Seasonal and daily fluctuations in milk TGF-β2 concentrations warrant further study.
    Pediatric Allergy and Immunology 09/2011; 22(8):853-61. · 3.38 Impact Factor