Progesterone regulates epidermal growth factor receptor on mucous secreting cells in the rabbit endocervix

Does progesterone inhibit bacteria-stimulated interleukin-8 production by lower genital tract epithelial cells?

OBJECTIVE

Progesterone (P(4)) has been clinically shown to prevent the recurrence of preterm birth. The mechanism(s) of action is unclear, but may involve modulation of the immunologic inflammatory response of the lower genital tract. We evaluated the effects of P(4) on interleukin-8 (IL-8) production by vaginal and cervical epithelial cells stimulated with bacterial species that are commonly associated with preterm birth.

METHODS

Vaginal and endocervical epithelial cells were incubated with up to 10,000 ng/mL P(4) overnight and stimulated with heat-killed Escherichia coli, Gardnerella vaginalis, or Ureaplasma urealyticum. Concentrations of IL-8 in conditioned medium were quantified by ELISA and viability of the cell cultures was measured by the reduction of a tetrazolium salt.

RESULTS

E. coli, G. vaginalis and U. urealyticum-stimulated IL-8 production for both cell lines. P(4) inhibited basal and bacteria-stimulated IL-8 production for vaginal epithelial cells but enhanced IL-8 production by endocervical cells. P(4) reduced the number of viable cells for both cell lines.

CONCLUSIONS

P(4) inhibits IL-8 production by vaginal epithelial cells stimulated with pathogens associated with preterm birth, possibly by reducing the number of viable cells or by inhibiting their proliferation. Although P(4) also reduces proliferation of endocervical cells it also increases their production of IL-8.

A three-dimensional organotypic culture of the human uterine exocervix for studying mucosal epithelial differentiation and migrating leukocytes

We report on a three-dimensional organotypic culture in vitro of explants from the human uterine exocervix. Exocervical fragments (2-3 mm3) from pre-menopausal women were cultured on sponges submerged in Dulbecco's Modified Eagle's Medium containing p-nonylphenol and 10% fetal bovine serum for up to 3 weeks and the viability and cellular responses were assayed. The fragments were analyzed by immunohistochemistry for the expression and distribution of a broad spectrum of cellular markers: p63, Ki-67, involucrin, high molecular weight cytokeratins, estrogen receptor-alpha, vimentin, CD45, and CD31. The fragments preserved their tissue architecture and cellular heterogeneity comparable to that observed in exocervical tissue in vivo. Prior to culture, the original epithelium was composed of stratified multilayered keratinocytes with integrated monocyte/dendritic-like cells in the basal and suprabasal layers. The epithelium began to exfoliate in culture and within 4 days appeared to have lost its differentiated high-zone layers of keratinocytes. After 10 days a new epithelium, slightly different from the original one, was formed; it displayed an increasing prominence of basal and suprabasal keratinocyte layers, containing infiltrating leukocytes that had probably migrated from the submucosa. The epithelium subsequently lost its organization, concomitant with a progressive involution of the stroma. Subepithelial capillaries appeared to be well maintained throughout the culture period. Aside from the maintenance of cellular heterogeneity within the fragments of exocervix, these culture systems are a valuable tool for studying the mechanisms of epithelial regeneration, and may prove to be a useful model for studying mucosal immunity.

Relationship of epidermal growth factor receptors to goblet cell production in human bronchi

To determine the relationship of epidermal growth factor receptor (EGFR) expression to mucin synthesis in human airways, we examined EGFR and MUC5AC expression at both gene and protein levels using in situ hybridization and immunohistochemical analysis in human bronchi. Bronchial mucosal biopsy specimens were obtained from 12 asthmatic subjects and 11 healthy subjects. In asthmatic airways, EGFR mRNA was expressed in the airway epithelium. EGFR immunoreactivity staining patterns varied among the asthmatic airways: staining was positive mainly in goblet cells, in basal cells, or in both. In contrast, healthy airways showed little expression of EGFR mRNA; EGFR immunoreactivity was observed mainly in goblet cells. In parallel to EGFR expression, MUC5AC mRNA expression was greater in asthmatic airways; mucous glycoconjugates that stained positively with Alcian blue/PAS were also increased in asthmatic airways. Ciliated cells were negative for EGFR and MUC5AC both in asthmatic and in healthy subjects at both mRNA and protein levels. There was a significant positive correlation between EGFR immunoreactivity and the area of MUC5AC-positive staining in both asthmatics and healthy subjects. These findings suggest a sequence of events by which EGFR activation is involved in mucin expression in asthmatic airway epithelium.

Morphological and morphometric analysis on the rabbit conjunctival goblet cells in different hormonal conditions

An altered conjunctival mucous secretion was reported in pregnancy or oral contraceptive use. Four groups of rabbits (males, dioestrous females, oestrous females, pregnant) were studied to determine whether sex and/or different physiological conditions could influence conjunctival goblet cells structure and ultrastructure. Light microscopy, transmission electron microscopy, and morphometry were performed. In males and in oestrous females the intracytoplasmic secretory granules were filled with granular material, whilst in pregnant and dioestrous females the granules were formed by a more homogenous and dense secretory material. The number of goblet cells was not statistically different in the groups studied, whilst pregnant animals showed the largest mean diameter. As to the secretory granules, their mean area was larger in dioestrous females, whilst their optical density was highest in pregnant animals. These observations indicate that the morphology of conjunctival goblet cell may vary according to sex and to different physiological conditions: this may account for the peculiar mucous secretion demonstrated during pregnancy.