ABSTRACT
Immune depression associated with prepubescent malnutrition underlies a staggering burden of infection-related morbidity. This investigation centered on dendritic cells as potentially decisive in this phenomenon. C57BL/6J mice, initially 19 days old, had free access for 14 days to a complete diet or to a low-protein formulation that induced wasting deficits of protein and energy. Mice were sensitized by i.p. injection of sheep red blood cells on day 9, at which time one-half of the animals in each dietary group received a simultaneous injection of 10(6) syngeneic dendritic cells (JAWS II). All mice were challenged with the immunizing antigen in the right hind footpad on day 13, and the 24-hour delayed hypersensitivity response was assessed as percentage increase in footpad thickness. The low-protein diet reduced the inflammatory immune response, but JAWS cells, which exhibited immature phenotypic and functional characteristics, increased the response of both the malnourished group and the controls. By contrast, i.p. injection of 10(6) syngeneic T cells did not influence the inflammatory immune response of mice subjected to the low-protein protocol. Antigen-presenting cell numbers limited primary inflammatory cell-mediated competence in this model of wasting malnutrition, an outcome that challenges the prevailing multifactorial model of malnutrition-associated immune depression. Thus, a new dendritic cell-centered perspective emerges regarding the cellular mechanism underlying immune depression in acute pediatric protein and energy deficit.
Subject(s)
Dendritic Cells/immunology , Diet, Protein-Restricted/adverse effects , Immunity, Cellular , Inflammation/immunology , Protein-Energy Malnutrition/immunology , Adoptive Transfer , Animals , Dendritic Cells/transplantation , Female , Flow Cytometry , Male , Mice , Mice, Inbred C57BL , T-Lymphocytes/immunology , T-Lymphocytes/transplantation , Wasting Syndrome/etiology , WeaningABSTRACT
In type 2 diabetes (T2DM) beta-cell responsiveness to glucose-dependent insulinotropic polypeptide (GIP) is reduced. In a model of T2DM, the VDF Zucker rat, GIP receptor mRNA and protein levels were shown to be down-regulated. Possible restoration of responsiveness to GIP in Zucker rats by reducing hyperglycemia has been examined. ZDF rats with extreme hyperglycemia demonstrated greater islet GIP receptor mRNA down-regulation (94.3+/-3.8%) than ZF rats (48.8+/-22.8%). GIP receptor mRNA levels in ZDF rats returned to 83.0+/-17.9% of lean following normalization of hyperglycemia by phlorizin treatment and pancreas perfusions demonstrated markedly improved GIP responsiveness. Treatment of VDF rats with a DP IV inhibitor (P32/98) resulted in improved glucose tolerance and restored sensitivity to GIP in isolated pancreata. These findings support the proposal that GIP receptor down-regulation in rodent T2DM is secondary to chronic hyperglycemia and that normalization of glycemia can restore GIP sensitivity.
