Prolactin inhibits carbachol-dependent secretion by lacrimal acinar cells in vitro

TFOS DEWS II Sex, Gender, and Hormones Report

One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. "Gender" and "sex" are words that are often used interchangeably, but they have distinct meanings. "Gender" refers to a person's self-representation as a man or woman, whereas "sex" distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.

Comparison of the effects of different lens-cleaning solutions on the protein profiles of human conjunctival cells

BACKGROUND

Many contact lens wearers suffer from dry eye syndrome. Previous studies show significant changes in the protein composition of the tears depending on the lens-cleaning solution used. Therefore, the aim of this study was to detect the influence of different lens solutions on conjunctival cells, cells also involved in tear film composition.

METHODS

Conjunctival epithelium cells (HCjE; IOBA-NHC) were exposed to medium containing Complete® Multipurpose Solution Easy Rub® Formula (Complete) (AMO) or Opti-Free® Express Multipurpose Disinfecting Solution (Opti-Free) (Alcon) in different concentrations (0.1, 0.5, 1, 2.5 %) for 12 and 24 h. Apoptosis and necrosis using FACS and protein profiles of the cells using SELDI-TOF-MS and MALDI-TOF-MS were measured. Multivariate statistics were calculated to detect the most significant changes.

RESULTS

Complex protein profiles were measured with SELDI-TOF-MS and MALDI-TOF-MS. Significant differences of protein profiles between control and treatment cells were detected after 12 and 24 h, although cells incubated with Complete showed significantly fewer changes than cells incubated with Opti-Free, also showing concentration-dependent changes of some significantly changed proteins, e.g., protein at 6,736 Da (p > 0.002). Cells incubated with Complete showed significantly less apoptosis or necrosis in comparison to control cells (p < 0.05), whereas cells incubated with Opti-Free showed significantly more (p < 0.05).

CONCLUSIONS

We were able to demonstrate that Complete shows very little effect on the protein profiles of conjunctival cells in comparison to Opti-Free, where the cells showed very large protein profile changes, and apoptosis and necrosis of the cells was increased. These results are in concordance to clinical studies showing that the use of Complete solution made the tear film proteins similar to those of people not wearing contact lenses. Therefore, we believe that Complete is less aggressive and should provoke fewer side-effects, such as dry eye syndrome, for the users.

Tearful relationships? Sex, hormones, the lacrimal gland, and aqueous-deficient dry eye

Sex and the endocrine system exert a significant influence on the physiology and pathophysiology of the lacrimal gland. The purpose of this article is to briefly review the nature and magnitude of these interactions between sex, hormones and lacrimal tissue, and to address how they may relate to the pathogenesis of aqueous-deficient dry eye. Towards this end, this article has a 3-fold approach: first, to summarize the influence of androgens, estrogens, glucocorticoids, mineralocorticoids, retinoic acid, prolactin, alpha-melanocyte stimulating hormone, adrenocorticotropic hormone, luteinizing hormone, follicle-stimulating hormone, growth hormone, thyroid-stimulating hormone, arginine vasopressin, oxytocin, thyroxine, parathyroid hormone, insulin, glucagon, melatonin, human chorionic gonadotropin and cholecystokinin on the structure and function of the lacrimal gland; second, to discuss the mechanism of action of each hormone on lacrimal tissue; and third, to discuss the clinical relevance of the endocrine-lacrimal gland interrelationship, with a particular focus on each hormone's role (i.e. if relevant) in the development of aqueous-tear deficiency.

Elevated prolactin redirects secretory vesicle traffic in rabbit lacrimal acinar cells

During pregnancy, lymphocytes infiltrating the rabbit lacrimal gland disperse to the interacinar space from their normal focal concentrations, basal fluid secretion decreases, pilocarpine-induced fluid secretion increases, and stimulated fluid protein concentration decreases. Ductal epithelial cell prolactin (PRL) content increases and redistributes from the apical to the basal-lateral cytoplasm. A replication-incompetent adenovirus vector for rabbit PRL (AdPRL) was used to test the hypothesis that increased intracrine/autocrine PRL signaling alters secretory protein traffic in an ex vivo lacrimal acinar cell model. AdPRL had no discernable influence on microtubules or actin microfilaments or their responses to carbachol (CCh). Endogenous and transduced PRLs exhibited similar, nonpolarized, punctate distributions. Cells secreted PRL consititutively and at increased rates in response to CCh. In contrast, constitutive secretion of beta-hexosaminidase was negligible, suggesting that the constitutive pathway for PRL is relatively inaccessible to typical secretory proteins. AdPRL had no significant effect on total secretion of beta-hexosaminidase or syncollin-green fluorescent protein (GFP), a chimeric secretory protein construct. However, it reversed the polarized distributions of vesicles containing rab3D and syncollin-GFP. Live-cell imaging indicated that AdPRL redirected CCh-dependent syncollin-GFP exocytosis from the apical plasma membrane to the basal-lateral membrane. Elevated concentrations of exogenous rabbit PRL in the ambient medium elicited similar changes. These observations suggest that elevated PRL, as occurs in the physiological hyperprolactinemia of pregnancy, induces lacrimal epithelial cells to express a mixed exocrine/endocrine phenotype that secretes fluid to the acinus-duct lumen but secretes proteins to the underlying tissue space. This phenotype may contribute to the pregnancy-associated immunoarchitecture.