Adherence of type 1-piliated Escherichia coli to carbohydrate structures of vaginal mucosa plays a major role in the pathogenesis of ascending urinary tract infections in women. Colonization of the vaginal introitus is influenced by interactions between pathogens, vaginal fluid, and vaginal epithelium. In this study, the type and amount of carbohydrates and glycoproteins present in vaginal fluid were determined. Free and protein-bound oligosaccharides in vaginal fluid specimens were analyzed by fluorophore-assisted carbohydrate electrophoresis (FACE) and high-pressure liquid chromatography (HPLC). Two-dimensional electrophoretic separations of vaginal fluid glycoproteins were performed together with bacterial overlay assays. The results of FACE showed that the majority of the oligosaccharides are in the free state and the bound oligosaccharides are undetectable. HPLC analysis of free sugars revealed glucose as the major sugar (3.3 ؎ 0.3 mM), and the concentrations of mannose and glucosamine were 0.065 ؎ 0.04 and 0.02 ؎ 0.001 mM, respectively. Radiolabeled E. coli bound three vaginal fluid glycoproteins with the following molecular masses and pIs: 82 kDa and pI 5.5, 55 kDa and pI 4.5, and 55 kDa and pI 6.5. The binding was inhibited by mannose and by deglycosylation of the proteins prior to the overlay assay. One of these putative receptors was identified to be the heavy chain of secretory IgA (S-IgA). These data suggest that the free mannose in the fluid is less than that required to affect E. coli-epithelial cell binding interactions and that S-IgA may bind E. coli in the vaginal introitus.
Anatomical localization of cellular retinol-binding protein (CRBP) mRNA was examined in normal rat testis and epididymis and also in retinoid-deficient rat testis. In situ hybridization was performed with 35S-labeled rat CRBP cRNA probes on frozen tissue sections. In normal testis, CRBP mRNA was mainly localized in the Sertoli cells and to some extent in peritubular cells. A distinct cyclic variation of the relative levels of hybridizable CRBP mRNA was observed during the spermatogenic cycle. The peak of CRBP mRNA content was seen in the stages of the cycle that preceded those in which peak CRBP protein content had been observed previously in our laboratory by immunohistochemistry. No appreciable amount of CRBP mRNA was observed in the interstitial space or in the lumen of the tubules. CRBP mRNA displayed the same anatomical localization in the retinoid-deficient testis, but the level of hybridizable CRBP mRNA was substantially reduced. A strong hybridization signal for CRBP mRNA was seen in proximal epididymis and was strikingly localized in the ductular epithelium. CRBP mRNA was not detectable in the distal portion of the epididymis. These studies provide information about the cell-specific expression of CRBP synthesis within the testis and epididymis and about its cyclic variation and regulation.
This model system should facilitate studies on the interaction of pathogens with vaginal mucosal cells, an essential step in the progression of ascending UTIs in women.
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