Desmosomes are reduced in the mouse uterine luminal epithelium during the preimplantation period of pregnancy: a mechanism for facilitation of implantation.

Dynamic regulation of intercellular junctions is an essential aspect of many developmental, reproductive, and physiological processes. We have shown that expression of the desmosomal protein desmoplakin decreases in the luminal uterine epithelium during the preimplantation period of pregnancy in mice. By the time of implantation (between Days 4.5 and 5 of pregnancy), desmoplakin protein can barely be detected by SDS-PAGE and Western blotting, and by immunocytochemistry, it is restricted to well-spaced, punctate dots at the apicolateral junction. Using confocal XZ series and electron microscope quantitation, both the density and distribution of desmosomes along the lateral cell surfaces of luminal epithelial cells were observed to change during early pregnancy. On Day 1 of pregnancy, desmosomes were found at high density in the apicolateral junctional complex, being present here in 79% of ultrathin sections examined, whereas on Day 5, the density was much reduced (present in only 18% of ultrathin sections examined). Desmosomes were found along the lateral surfaces, at or below the level of the nucleus, in 15% of ultrathin sections examined on Day 1 of pregnancy but in only 1% on Day 5. Desmoplakin mRNA declined during the first 4-5 days of pregnancy, along with the protein, suggesting that these changes are controlled at the level of mRNA. This study shows that desmosomes are regulated during early pregnancy, and we propose that a reduction in desmosome adhesion facilitates penetration of the luminal epithelium by trophoblast cells at implantation.

Oral DNA vaccination promotes mucosal and systemic immune responses to HIV envelope glycoprotein.

In this report, we described induction of HIV envelope (env)-specific systemic and mucosal immune responses by oral vaccination of BALB/c mice with env-encoded plasmid DNA encapsulated in poly(dl-lactide-co-glycolide) (PLG) microparticles. We demonstrated that intragastric administration of the encapsulated plasmid DNA resulted in transduced expression of the env glycoprotein in the intestinal epithelium. Mice immunized orally exhibited env-specific type 1 and cytotoxic T lymphocyte (CTL) responses in spleen and the inductive (Peyer's patches) and effector (lamina propria) mucosal tissues of gut. Oral administration of PLG-encapsulated plasmid DNA encoding gp160 also induced env-specific serum antibodies, and an increased level of IgA directed to gp160 was detected in fecal washes of the immunized mice. In contrast, intramuscular (i.m.) administration of naked or PLG-encapsulated DNA vaccine induced only systemic cellular and humoral responses to the env glycoprotein. Using an HIV env-expressing recombinant vaccinia viral intrarectal murine challenge system, we observed higher resistance to mucosal viral transmission in mice immunized orally than in animals injected i.m. with PLG-encapsulated plasmid DNA encoding gp160. Results of these studies demonstrate the feasibility of using orally delivered PLG microparticles containing plasmid DNA-encoded HIV gp160 for induction of env-specific systemic and mucosal immune responses and protection against recombinant HIV env vaccinia virus challenge.