Katherine C. Lantz

The toll-like receptor 7 (TLR7) agonist, imiquimod, and the TLR9 agonist, CpG ODN, induce antiviral cytokines and chemokines but do not prevent vaginal transmission of simian immunodeficiency virus when applied intravaginally to rhesus macaques

ABSTRACT The initial host response to viral infection occurs after Toll-like receptors (TLRs) on dendritic cells (DC) are stimulated by viral nucleic acids (double-stranded RNA, single-stranded RNA) and alpha interferon (IFN-α) and IFN-β are produced. We hypothesized that pharmacologic induction of innate antiviral responses in the cervicovaginal mucosa by topical application of TLR agonists prior to viral exposure could prevent or blunt vaginal transmission of simian immunodeficiency virus (SIV). To test this hypothesis, we treated rhesus monkeys intravaginally with either the TLR9 agonist, CpG oligodeoxynucleotides (ODN), or the TLR7 agonist, imiquimod. Both immune modifiers rapidly induced IFN-α and other antiviral effector molecules in the cervicovaginal mucosa of treated animals. However, both CpG ODN and imiquimod also induced proinflammatory cytokine expression in the cervicovaginal mucosa. In the vaginal mucosa of imiquimod-treated monkeys, we documented a massive mononuclear cell infiltrate consisting of activated CD4+ T cells, DC, and beta-chemokine-secreting cells. After vaginal SIV inoculation, all TLR agonist-treated animals became infected and had plasma vRNA levels that were higher than those of control monkeys. We conclude that induction of mucosal innate immunity including an IFN-α response is not sufficient to prevent sexual transmission of human immunodeficiency virus.

Preference of Invasive Cytotrophoblast for Maternal Vessels in Early Implantation in the Macaque

The interaction of cytotrophoblast with maternal endometrium, especially endometrial blood vessels, was examined in macaque gestational stages between 2 and 8 days after the onset of implantation. Serial sectioning of these early implantation sites allowed immunostaining of consecutive sections with a number of different antibodies, facilitating cell identification. In the earliest implantation site, immunostaining showed that antibody to cytokeratin stained cytotrophoblast, syncytial trophoblast, epithelial plaque and endometrial gland cells. However, only those cytotrophoblast cells near the maternal-fetal border and within vessels showed surface staining for neural cell adhesion molecules and only syncytial trophoblast showed SP1 reactivity. Even at this early stage cytotrophoblast filled the lumen of superficial arterioles, whereas dilated venules contained only a few cytotrophoblast cells. In later stages endovascular cytotrophoblast not only plugged many spiral arterioles but also migrated into the walls of these arterioles, and progressed into deeper coils. Displacement of endothelial cells and disruption of vessel walls were illustrated with antibody to factor VIII, TGF alpha, and desmin. Clusters of cytotrophoblast cells at the fetal-maternal interface tended to bypass clusters of epithelial plaque cells and larger clusters of maternal fibroblasts, but readily entered all vascular spaces. Consequently the vascular system constituted a major pathway of invasion, although the arterioles were the only component substantially invaded beyond the trophoblastic-shell/endometrial border.

Morphological variation in the interhemal areas of chorioallantoic placentae

Summary The cellular and extracellular matrix layers intervening between fetal and maternal blood in definitive chorioallantoic placentae of eutherian mammals are highly varied. Some patterns, such as reduced distance between blood streams and direct bathing of trophoblast by maternal blood, have obvious advantages. Others, such as the prevalence of hypertrophy of maternal endothelium and the interstitial lamina in endotheliochorial placentae and the tendency of processes from the maternal endothelium to abut processes from the cytotrophoblast through a thickened interstitial lamina, have no apparent advantage. Individual cells within the placental stroma that exhibit features of endocytosis (Hofbauer cells) or protein synthesis (rER-rich cells) do not correlate with chorioallantoic placental type. Further comparative studies may help unravel the functional roles of the different layers in the kaleidoscope of placental types. In this rather rapid romp through comparative placentation, we have deliberately chosen a number of species that might not be familiar to the majority of placentologists. We have done this both to illustrate the diversity of morphological relationships, to hopefully encourage more studies using these species, and because of a personal fascination with the variations in the structures that successfully cope with the peculiar problems of intrauterine gestation. With the current increase in availability of antibodies for labeling specific moieties and improvements in antigen retrieval methods, it should be possible to not only extend our knowledge of placental diversity but also to obtain clues to the positional significance of some of the placental structures.

Possible significance of cells within intraluminal collagen masses in equine oviducts.

In addition to the unique feature of retention of unfertilized ova, the oviducts of mares frequently contain large intraluminal masses with a fibrillar component and some cells. The aim of this study was to identify the cells and examine their relationship to the extracellular components of these masses. Intraluminal masses were examined both in situ and flushed from the oviducts. The nature of the contained cells and their relationship to the fibrils were examined by light microscopy and by transmission and scanning electron microscopy. In some mares the large masses distended the oviduct, but neither loss of the oviductal epithelium nor damage to this epithelium was seen. Electron microscopy verified that the principal cellular component was fibroblasts, and that the fibrils were type I collagen. Collagen masses collected shortly after ovulation frequently contained viable fibroblasts with collagen fibrils associated with their cell surfaces and with surface clefts. Although such collagen masses were present in pregnant and nonpregnant mares, masses with viable fibroblasts were chronologically associated with recent ovulation.

Exposure of cynomolgus monkey embryos to retinoic acid causes thymic defects: effects on peripheral lymphoid organ development.

We have previously reported that exposure of monkey embryos to 13‐cis‐retinoic acid (cRA) results in thymic defects. In this study, we analyzed lymphocyte and antigen‐presenting cell populations at gestational days (GDs) 80–100 in the thymus, spleen, mesenteric lymph nodes, and gut‐associated lymphoid tissue following a teratogenic dosing regimen of cRA (2.5 and 5 mg/kg) at GD14–27. Tissue sections were immunostained for T‐cells (anti‐CD3), B‐cells (anti‐CD20), dendritic cells (p55), and major histocompatibility class II (anti‐HLA‐DR). Digital images of spleen sections were analyzed to obtain the relative area occupied by the cell subsets within the white pulp (WP). Compared with controls, the T‐cell dependent compartment of the spleen WP in specimens with perturbed thymic development (aplasia and severe hypoplasia) showed a reduction in size and proportion of CD3+ T cells. Our findings indicate that cRA‐induced thymic defects result in disrupted development of the splenic T‐cell dependent compartment.

Ultrastructural localization of pregnancy-specific β1-glycoprotein (SP1) and cathepsin B in villi of early placenta of the macaque

Pregnancy-specific beta 1-glycoprotein (SP1) is found in maternal serum very early in gestation in both human and non-human primates. As judged by light microscopic immunocytochemistry, the major source of SP1 is the syncytial trophoblast, but little is known of the subcellular localization of SP1 indicative of the cellular pathway involved in secretion of the hormone. To study subcellular distribution of SP1, we used electron microscopic immunocytochemistry carried out on macaque placental villi from early (3-4 weeks) gestation. Both light and electron microscopic results confirmed localization confined to syncytial trophoblast in the villi. Within syncytial trophoblast labeling was predominantly over small granules in the apical cytoplasm. The Golgi complex also showed labeling, and light labeling was associated with the endoplasmic reticulum. For comparison, we also localized cathepsin B, a lysosomal protease. By way of contrast this enzyme was localized primarily in large cytoplasmic granules. The results are consistent with a secretory pathway including synthesis in the ER, processing by the Golgi complex, and exocytotic release into maternal blood in the intervillous space.