Chiharu Kubo

Bio: Chiharu Kubo is an academic researcher from Kyushu University. The author has contributed to research in topics: Anxiety & Anorexia nervosa (differential diagnoses). The author has an hindex of 40, co-authored 179 publications receiving 7438 citations. Previous affiliations of Chiharu Kubo include Oklahoma Medical Research Foundation & University of Oklahoma.

Postnatal microbial colonization programs the hypothalamic-pituitary-adrenal system for stress response in mice.

Abstract: Indigenous microbiota have several beneficial effects on host physiological functions; however, little is known about whether or not postnatal microbial colonization can affect the development of brain plasticity and a subsequent physiological system response. To test the idea that such microbes may affect the development of neural systems that govern the endocrine response to stress, we investigated hypothalamic–pituitary–adrenal (HPA) reaction to stress by comparing germfree (GF), specific pathogen free (SPF) and gnotobiotic mice. Plasma ACTH and corticosterone elevation in response to restraint stress was substantially higher in GF mice than in SPF mice, but not in response to stimulation with ether. Moreover, GF mice also exhibited reduced brain-derived neurotrophic factor expression levels in the cortex and hippocampus relative to SPF mice. The exaggerated HPA stress response by GF mice was reversed by reconstitution with Bifidobacterium infantis. In contrast, monoassociation with enteropathogenic Escherichia coli, but not with its mutant strain devoid of the translocated intimin receptor gene, enhanced the response to stress. Importantly, the enhanced HPA response of GF mice was partly corrected by reconstitution with SPF faeces at an early stage, but not by any reconstitution exerted at a later stage, which therefore indicates that exposure to microbes at an early developmental stage is required for the HPA system to become fully susceptible to inhibitory neural regulation. These results suggest that commensal microbiota can affect the postnatal development of the HPA stress response in mice.

The requirement of intestinal bacterial flora for the development of an IgE production system fully susceptible to oral tolerance induction.

Abstract: The role of intestinal bacterial flora in oral tolerance induction to the IgE response was investigated using germfree (GF) mice. When GF mice were orally administered 20 mg of OVA as tolerogen before a systemic challenge with OVA, the Th1-mediated responses, such as the production of IgG2a and IFN-gamma, were abrogated, while the Th2-mediated immune responses, such as the production of IgE, IgG1, and IL-4, were maintained. Moreover, the basal level of IL-4 production in vitro was significantly higher in the GF mice than that of IL-4 in specific pathogen-free mice when challenged systemically with OVA. On the other hand, both Th1 and Th2 responses were fully sensitive to such tolerance induction in specific pathogen-free mice. The reconstitution of intestinal flora of GF mice with Bifidobacterium infantis, one of the predominant bacteria in the intestinal flora, restored the susceptibility of these Th2 responses to oral tolerance induction; however, this was only effective when such reconstitution was performed in neonates, but not in mice at an older age. These results thus suggested that intestinal bacterial flora play a crucial role in generating a Th2 cell population whose size and response are adequately regulated and, consequently, fully susceptible to oral tolerance induction, probably by affecting the development of gut-associated lymphoid tissue at the neonatal stage.

Aggressive behavior and serum testosterone concentration during the maturation process of male mice: the effects of fetal exposure to bisphenol A.

Abstract: The relationship between exposure to endocrine-disrupting chemicals (EDs) and risk to reproductive organs is well documented, but the influence of EDs on behavioral development has not been studied. In this study we evaluated the effect of fetal exposure to bisphenol A, which mimics estrogenic activity, on aggressive behavior and hormonal change in male mice. On gestation days 11-17, female mice were fed bisphenol A at 2 ng/g or 20 ng/g of body weight (environmentally relevant concentration). Aggression rating and blood sampling of the offspring were done at 8, 12, and 16 weeks of age. Aggression scores increased significantly (p < 0.01) at 8 weeks of age in male mice exposed to bisphenol A at both the 2 ng/g and 20 ng/g concentrations compared with a control group, but no difference was found after 12 weeks. Relative testis weight (per gram of body weight) was significantly lower at 8 and 12 weeks in mice treated with 2 ng/g than in controls (p < 0.05) and was significantly lower at 12 weeks in mice treated with 20 ng/g than in controls (p < 0.01). The serum testosterone concentration in treated mice was not significantly different from that in controls. These results demonstrate that bisphenol A temporarily activated aggressive behavior in mice at 8 weeks of age and that low doses of bisphenol A interfered with the normal development of reproductive organs. The mechanism activating this aggressive behavior was not elevated testosterone concentration.

Antibiotic use during infancy promotes a shift in the TH1/TH2 balance toward TH2-dominant immunity in mice

Abstract: Background: Recent epidemiologic studies indicate that antibiotic use in infancy may be associated with an increased risk of development of atopy; however, its precise mechanism remains to be elucidated. Objective: The purpose of this study is to clarify whether one such antibiotic, kanamycin, affects the T H 1/T H 2 balance. Methods: BALB/c mice at 3 and 52 weeks of age were orally administered 600 mg/d kanamycin sulfate for 7 consecutive days. Blood samples were collected on weeks 0, 10, 18, and 26 after the cessation of kanamycin treatment, and the effect of the kanamycin treatment on the T H 1/T H 2 balance was evaluated on the basis of both the in vivo antibody levels and the in vitro splenocyte cytokine secretion pattern. Results: The administration of kanamycin increased the serum levels of total IgG1 and IgE while decreasing the serum IgG2a levels. Moreover, when spleen cells were stimulated with immobilized anti-CD3 antibody in vitro, such kanamycin treatment enhanced the in vitro IL-4 secretion while reducing the in vitro IFN-γ secretion. The basal IL-12 p70 secretion levels of splenic dendritic cells in the kanamycin-treated mice were lower than those in the control mice, although no significant difference was seen in IL-12 p40 levels between either group of mice. Conclusion: These results suggested that antibiotic use during infancy may indeed quantitatively disturb, qualitatively disturb, or both the intestinal microflora and thereby prevent postnatal T H 1 cell maturation, thus resulting in a T H 2-polarized immune deviation. (J Allergy Clin Immunol 2001;107:153-9.)

The effects of psychological intervention on atopic dermatitis. A systematic review and meta-analysis.

Abstract: Background: Psychological interventions may be valuable in atopic dermatitis. We systematically reviewed and carried out a meta-analysis of randomized controlled trials of psycholog

Gut Microbiota in Health and Disease

Abstract: Gut microbiota is an assortment of microorganisms inhabiting the length and width of the mammalian gastrointestinal tract. The composition of this microbial community is host specific, evolving throughout an individual's lifetime and susceptible to both exogenous and endogenous modifications. Recent renewed interest in the structure and function of this "organ" has illuminated its central position in health and disease. The microbiota is intimately involved in numerous aspects of normal host physiology, from nutritional status to behavior and stress response. Additionally, they can be a central or a contributing cause of many diseases, affecting both near and far organ systems. The overall balance in the composition of the gut microbial community, as well as the presence or absence of key species capable of effecting specific responses, is important in ensuring homeostasis or lack thereof at the intestinal mucosa and beyond. The mechanisms through which microbiota exerts its beneficial or detrimental influences remain largely undefined, but include elaboration of signaling molecules and recognition of bacterial epitopes by both intestinal epithelial and mucosal immune cells. The advances in modeling and analysis of gut microbiota will further our knowledge of their role in health and disease, allowing customization of existing and future therapeutic and prophylactic modalities.

Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour

Abstract: Recent years have witnessed the rise of the gut microbiota as a major topic of research interest in biology. Studies are revealing how variations and changes in the composition of the gut microbiota influence normal physiology and contribute to diseases ranging from inflammation to obesity. Accumulating data now indicate that the gut microbiota also communicates with the CNS — possibly through neural, endocrine and immune pathways — and thereby influences brain function and behaviour. Studies in germ-free animals and in animals exposed to pathogenic bacterial infections, probiotic bacteria or antibiotic drugs suggest a role for the gut microbiota in the regulation of anxiety, mood, cognition and pain. Thus, the emerging concept of a microbiota-gut-brain axis suggests that modulation of the gut microbiota may be a tractable strategy for developing novel therapeutics for complex CNS disorders.