Changes of glial Na+-K+ ATPase (alpha 1 subunit) immunoreactivity in the gerbil hippocampus after transient forebrain ischemia.

In the present study to evaluate the effects of ischemia on sodium-potassium adenosine triphosphatase (Na(+)-K+ ATPase) alpha1 subunit (alpha6F) expression in the glia, the immunodensities of both Na(+)-K+ ATPase and the glial fibrillary acidic protein in the hippocampus were measured and analyzed. In the sham hippocampus, alpha6F immunoreactivity was mainly observed in the both the molecular layer and the polymorphic layer of dentate gyrus. At 30 min after ischemic insult, the alpha6F immunoreactivity was markedly decreased in the molecular layer of the dentate gyrus, in contrast to the appearance of this immunoreactivity in the hilar neurons. Up to 12 h after ischemic insult, the alpha6F immunoreactivity was re-enhanced in the molecular layer of dentate gyrus. In addition, the alpha6F immunoreactivity appeared slightly in the glial components in the hippocampal region. Four days after ischemia-reperfusion, the intensity of alpha6F immunoreactivity in the glial cells was highest. At this time point, strong alpha6F immunoreactivity was colocalized with GFAP immunoreactivity in the strata radiatum of the CA1 and the molecular layer of the dentate gyrus. These results suggest that the enhancement of alpha6F immunoreactivity may be a compensatory response to regulate the ion homeostasis in the brain. In addition, the maintenance of Na(+)-K+ ATPase activity in the astrocytes may explain the resistant characteristics of these cells to ischemic insults.

CD4+ TH1 cells generated by Ii-PADRE DNA at prime phase are important to induce effectors and memory CD8+ T cells.

The requirement for CD4 T cells in priming and maintaining cytotoxic T-lymphocyte responses presents a long-standing paradox in cellular immunology. In this study, we used sequential coadministration of a DNA vaccine encoding an invariant (Ii) chain in which the class II-associated Ii-peptide region is replaced with CD4 T-helper epitope, PADRE [Pan human leukocyte antigen-DR reactive epitope (Ii-PADRE)] or Bcl-xL with a DNA vaccine encoding Sig/E7/LAMP-1 to verify the role of CD4 T cells for the generation of effectors and memory E7-specific CD8 T-cell immune responses. Sequential vaccination, with Ii-PADRE+Sig/E7/LAMP-1 priming followed by Bcl-xL+Sig/E7/LAMP-1 boosting led to generation of E7-specific CD8 T cells, and was nearly equivalent in effect to coadministration with Ii-PADRE+Sig/E7/LAMP-1 or Bcl-xL+Sig/E7/LAMP-1 at both prime and boost. The mice vaccinated with the Ii-PADRE+Sig/E7/LAMP-1 prime-Bcl-xL+Sig/E7/LAMP-1 boost regimen exhibited better long-term E7-specific immune responses and tumor prevention effects in vivo than the mice vaccinated with the reverse sequential coadministration. After CD4 T-cell depletion, mice primed with Ii-PADRE+Sig/E7/LAMP-1 generated low numbers of E7-specific CD8 T cells and suppressed long-term memory CD8 T-cell response regardless of the sequence or combination of DNA vaccines administered. Mice primed with Bcl-xL+Sig/E7/LAMP-1 only suppressed long-term memory CD8 T-cell response after depletion of CD4 T cells before priming. Our findings suggest that activated CD4 T cells at prime phase are important to generate the antigen-specific CD8 T-cell immune responses and CD4 T cells, which are naive or activated, play a role to maintain the long-term memory responses.