'Ignorance' of antigen-specific murine CD4+ and CD8+ T cells is overruled by lipopolysaccharide and leads to specific induction of IFN-gamma

Effect of γ-aminobutyric acid on growth performance and immune function in chicks under beak trimming stress

This experiment was undertaken to examine the effect of beak trimming stress on the growth performance and immune system, and to consider possible roles of γ-aminobutyric acid (GABA) in this stress response. Results showed that body weight, feed intake and relative spleen weight were significantly increased by GABA at 80 mg/kg (P < 0.05) under beak trimming stress, whereas the relative organ weights of the bursa of fabricius and thymus were not significantly affected (P > 0.05). Adrenocorticotropic hormone concentration in serum was highest for chicks fed the GABA-deficient water and was significantly decreased by the supplement of GABA at days 1, 3 and 5 after beak trimming (P < 0.05). The supplement of GABA significantly increased the proportions of CD4(+) and CD8(+) lymphocytes, especially at the dose of 60 mg/kg (P < 0.05). The levels of interleukin (IL)-1β, lipopolysaccharide-induced tumor necrosis factor-α and IL-6 in serum were significantly decreased by GABA at 80 mg/kg (P < 0.05). All the three cytokines expressed in the spleen were significantly decreased by GABA at 80 mg/kg when birds were under beak trimming stress (P < 0.05). It is concluded that beak trimming suppressed the immune response of chicks, whereas the immune response of chicks could be improved by GABA supplementation.

Helicobacter pylori with a truncated lipopolysaccharide O chain fails to induce gastritis in SCID mice injected with splenocytes from wild-type C57BL/6J mice

The goal of this study was to determine whether Helicobacter pylori lipopolysaccharide (LPS) O-chain polysaccharide contributes to gastritis in a mouse model. C57BL/6J or C57BL/6-Prkdc(scid) (severe combined immunodeficient [SCID]) mice were inoculated with H. pylori strain SS1 or SS1::0826kan, in which a beta-1,4-galactosyltransferase (HP0826), an LPS biosynthetic enzyme, had been disrupted. H. pylori strain SS1::0826kan expresses truncated LPS lacking O chain. Recipient SCID mice were given C57BL/6J splenocytes by intraperitoneal injection. Bacterial colonization, gastric lesions (gastritis, neutrophilic infiltration, and gastric epithelial metaplasia), cellular (delayed-type hypersensitivity) and humoral immune responses to H. pylori sonicate, and gastric gamma interferon (IFN-gamma) mRNA expression were quantified. Recipient SCID mice colonized by H. pylori strain SS1 developed extensive gastritis with loss of normal fundic gland morphology. In contrast, gastric mucosa of recipient SCID mice colonized by H. pylori strain SS1::0826kan was not statistically distinguishable from that of uninfected recipient mice. Delayed-type hypersensitivity and humoral immune responses were detected in infected mice inoculated with wild-type SS1, but not with SS1::0826kan. IFN-gamma transcription was lower in mice infected with SS1::0826kan than in mice infected with SS1. In this model of rapidly progressive gastritis due to H. pylori, the O chain contributed to the extent of gastritis and to the host immune response. These data support a role for H. pylori LPS O chain in direct induction of the host immune response leading to gastritis and gastric damage and are in contrast to protein antigens, such as urease and cag products which do not contribute to gastritis in mice.