Kohya Hishinuma

The effect of dietary restriction on mouse T cell functions

Forty percent dietary restriction on 9-weeks-old C3H/He mice caused decrease of the weight of central lymphoid organs in parallel with the reduction of body weight. However, the percentage of splenic T cells was dramatically increased in diet-restricted mouse spleen cells. Generally, normal mouse spleen cells contained about 30% of Thy 1.2+ T cells, but the restricted mouse spleen cells contained 80% Thy 1.2+ T cells. Ly 1+, L3T4+ T cells, but not Ly 2+ T cells, also increased in diet-restricted mouse compared with the unrestricted mice. In parallel with the dramatic changes of splenic T cells, spleen cells obtained from diet-restricted mice showed higher immunological responses against alloantigen and interleukin 2. It was also demonstrated than nylon-passed splenic T cells obtained from diet-restricted mice showed higher levels of T cell responses against r-IL-2 and alloantigen, indicating that dietary restriction modulates T cell functions themselves.

Augmentation of mouse immune functions by dietary restriction : an investigation up to 1 year of age

Mice fed a 40% restricted diet until 1 year of age showed a 35% drop in body weight and markedly lower weights in the central lymphoid organs such as spleen and thymus than those of unrestricted mice. In contrast, the percentage of splenic Thy 1.2+ T cells was dramatically increased by dietary restriction. Splenic Ly 1+ T cells were also increased in the restricted mice. Spleen cells of the restricted mice revealed significantly higher responses not only in macrophage (MP)-dependent responses such as concanavalin A response and mixed-lymphocyte reaction but also in MP-independent T cell responses to recombinant interleukin 2 even at 1 year of age. These results strongly suggest that dietary restriction causes an enrichment of Thy 1.2+ T cells in spleen and augments the functions of T cells in mice.

Dietary restriction reduces the incidence of 3-methylcholanthrene-induced tumors in mice: close correlation with its potentiating effect on host T cell functions

SummaryAll mice treated with 3-methylcholanthrene (MC) suffered with tumor 114 days after treatment. However, 40% dietary restriction caused a great inhibition of tumor incidence. In order to understand the mechanisms by which dietary restriction decreased the occurrence of tumor in mice, we investigated the correlation between tumor incidence and host T cell immune responses. At 114 days after MC administration, the mice were sacrificed and their T cell immune responses were assessed. Flow cytometry studies demonstrated that dietary restriction caused a marked increase of the proportion of Thy1.2+, L3T4+ T cells in MC-treated diet-restricted mice. Consistent with this result, T cell responses against concanavalin A and interleukin-2 were also potentiated in spleen cells obtained from MC-treated diet-restricted mice, while spleen cells obtained from MC-treated unrestricted mice showed decreased T cell responses because of their tumor burden. Such potentiation of T cell functions by dietary restriction was also observed at earlier stages of MC-induced tumorigenesis. During the course of carcinogenesis, spleen cells obtained from diet-restricted mice showed decreased natural killer activity in vivo. However, in vitro induction of cytotoxic T cells was markedly augmented in MC-treated diet-restricted mice compared with unrestricted mice. These results strongly suggest that the increase of host T cell immune responses might be one of the major causes for the reduction of tumor occurrence by dietary restriction.

Glycolytic Inhibitor Failed to Inhibit Superoxide Generation in Mouse Macrophages: An Investigation Using a Chemiluminescence Probe Specific for Superoxide Anion

Glucose is widely known to be required during superoxide generation in phagocytic cells. However, when an specific chemiluminescence probe with the Cypridina luciferin analog 2-methyl-6-(p-methoxyphenyl)-3, 7 -dihydroimidazo[ 1,2-a]pyrazin-3-one (MCLA) was used, about 60% of the chemiluminescence remained in stimulated macrophages in the presence of the glycolytic inhibitor 2-deoxyglucose. -nonspecific luminol-dependent chemiluminescence disappeared when the same drug was added. These results clearly demonstrate that the generation of by macrophages is not completely glucose-dependent, and strongly suggest that macrophages have both glucoseindependent NADPH-supplying pathway(s) and glucose dependent pathway(s) which generate reactive oxygen species other than .

Identification of distinct pathways for superoxide generation in mouse macrophages: an investigation using a chemiluminescence probe specific for superoxide anion

Dependency of superoxide anion () generation on protein kinase C (PKC) or calmodulin (CaM) in macrophages (MPs) was investigated using a -specific chemiluminescence probe with the Cypridina luciferin analog 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[l,2-a]-pyrazin-3-one (MCLA). In opsonized zymosan (OZ)-stimulated MPs, 40% of the MCLA-dependent chemi-luminescence disappeared when the PKC inhibitor l-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) or the CaM antagonist N-(6-aminohexyl)-5-chloro-l-naphthalenesulfon-amide (W-7) was added. In MPs stimulated by 12-o-tetra-decanoylphorbol-13-acetate (TPA), addition of H-7 strikingly lowered MCLA-dependent chemiluminescence, but W-7 had only a little effect. These results indicate that both PKC and CaM are involved in OZ-stimulated generation in MPs and that TPA-stimulated generation depends not on CaM but on PKC.