Identification of androgen, estrogen and progesterone receptor mRNAs in the eye

Tear function tests and conjunctival impression cytology before and after hormone replacement therapy in postmenopausal women

PURPOSE

To investigate the effect of hormone replacement therapy (HRT) on postmenopausal tear function and the conjunctival epithelium.

METHODS

Schirmer I-Jones test, tear film break-up time (BUT), and impression cytology findings were analyzed in 34 eyes of 17 women who were at least two years postmenopausal and not taking HRT: This series of tests was repeated after three months on HRT.

RESULTS

The patients' average age was 53.82 +/- 3.6 years, and the mean time postmenopause was 35.29 +/- 11.59 months. There was no significant difference in the Schirmer I-Jones test results before and after three months of HRT (p > 0.05). However, the BUT (p < 0.05) and impression cytology (p < 0.05) findings were significantly affected by HRT.

CONCLUSIONS

HRT may alleviate postmenopausal dry eye symptoms by increasing goblet cell density.

Transporters/receptors in the anterior chamber: pathways to explore ocular drug delivery strategies

Membrane transporters/receptors are involved in drug transport processes and play a key role in intestinal absorption, tissue distribution and elimination. Drug targeting to specific transporters and receptors using carrier-mediated absorption has immense clinical significance. Ocular drug delivery is a challenging task since it involves drug transport across various barriers in the eye. Specialised transport processes exist at these barriers, which control the entry of drugs and xenobiotics. Ocular drug therapy involving topical or systemic administration of drugs has various limitations. Transport processes in the eye have been targeted in an effort to increase ocular bioavailability of drugs following topical instillation. This review discusses various transport processes in the eye and drug delivery strategies utilising these transporters/receptors.

Sex hormones and their receptors in patients with age-related cataract

PURPOSE

To determine the sex hormone levels in the serum and aqueous humor in patients with age-related cataract and the corresponding hormone receptors in cataract lens epithelial cells (LECs).

SETTING

Research Laboratory, International Intraocular Implant Training Center, Tianjin Medical University, Tianjin, China.

METHODS

Serum and aqueous humor were drawn from patients with cataract and a control group. Enzyme-linked immunosorbent assay was used to determine the levels of estradiol, progesterone, and testosterone in the serum and the aqueous. The anterior lens capsules with attached LECs were obtained during cataract surgery, and the expressions of estrogen receptor, progesterone receptor, or androgen receptor were examined by immunohistochemistry.

RESULTS

The testosterone level in the serum was significantly higher in the control group than in the cataract group. In the cataract group, there was no difference between sexes in the serum levels of estradiol or progesterone; however, the testosterone level in men was significantly higher than in women. The aqueous level of each hormone was lower than in serum; however, there was no difference between sexes and no association with corresponding serum levels. No estrogen, progesterone, or androgen receptor was detected in the LECs of patients with age-related cataract.

CONCLUSIONS

There was no statistical difference between men and women or between the cataract and control groups in the levels of estradiol or progesterone in serum. There was no between-sex difference in the aqueous levels. It appears that sex hormone levels can be regarded only as a risk factor for cataractogenesis, not as a key factor.

Down-regulation of androgen receptor expression and inhibition of lacrimal gland cell proliferation by retinoic acid

Androgens and retinoids are known to be involved in control of lacrimal gland function. Because retinoids generally antagonize androgen function it was the purpose of this study to investigate interactions of retinoic acid and androgens in rabbit lacrimal acinar cells in culture by determining effects of retinoic acid on androgen receptor (AR) mRNA expression, AR protein levels and androgen-stimulated cell proliferation. Experiments were conducted using primary rabbit lacrimal acinar cells and a transformed rabbit lacrimal acinar cell line. Exposure of primary lacrimal acinar cells in culture to 10(-10)-10(-6)M all-trans retinoic acid for 4-24hr causes an approximately 50% decrease in AR mRNA expression. Expression of AR protein in primary and transformed rabbit lacrimal acinar cells was confirmed by immunohistochemistry. Exposure of the primary cells to 10(-6)M retinoic acid for 24hr caused a 40% decrease in AR protein levels as determined by measurement of binding of(3) [H]-dihydrotestosterone (DHT) to cells in culture and Scatchard analysis. Exposure to 10(-9)-10(-6)M DHT stimulates proliferation of transformed rabbit lacrimal acinar cells. This effect is receptor mediated since it is blocked by the AR antagonist, flutamide. Proliferation of the lacrimal acinar cells is inhibited by retinoic acid, as compared to control, and retinoic acid also completely inhibits androgen stimulation of cell proliferation. This study supports the hypothesis that androgens play a supportive role in lacrimal gland function. The antagonistic influences of androgens and retinoic acid suggests that, under physiologic conditions there is a balance between the effects of androgens and retinoids in the lacrimal gland. A decrease in androgen levels in a dry eye patient may alter the balance between the effects of these important controllers of gene expression. The antagonistic effect of retinoids on androgens in the lacrimal gland must also be considered when devising pharmaceutical treatments for dye eye.

Expression of estrogen receptor in the choroidal neovascular membranes in highly myopic eyes

PURPOSE

To investigate the expression of estrogen receptor in choroidal neovascular membranes (CNVMs) surgically excised from eyes with high myopia.

METHODS

The CNVMs were surgically excised from two eyes with high myopia. Immunohistochemical analysis with a monoclonal antibody to estrogen receptor and in situ hybridization with an oligodeoxynucleotide sequence coding for estrogen receptor were used to study the cellular distribution of estrogen receptor and its messenger RNA in the CNVMs. Immunohistochemical localization of glial fibrillary acidic protein and vimentin in the CNVMs was compared with localization of estrogen receptor.

RESULTS

Immunohistochemical analysis with monoclonal antibody to estrogen receptor showed widespread staining throughout the CNVMs. By in situ hybridization, the expression of estrogen receptor messenger RNA was predominantly observed in the CNVMs. Staining with antibody to vimentin was widespread throughout the CNVMs, which was similar to the localization of estrogen receptor.

CONCLUSION

Estrogen receptor was expressed in the CNVMs in highly myopic eyes, suggesting that estrogen may have important functions in the formation of CNVMs.

Androgen deficiency, Meibomian gland dysfunction, and evaporative dry eye

OBJECTIVE

We have recently discovered that women with primary and secondary Sjögren's syndrome are androgen-deficient. We hypothesize that this hormone insufficiency contributes to the meibomian gland dysfunction, tear film instability, and evaporative dry eye that are characteristic of this autoimmune disorder. If our hypothesis is correct, we predict: (1) that androgens regulate meibomian gland function, control the quality and/or quantity of lipids produced by this tissue, and promote the formation of the tear film's lipid layer; and (2) that androgen deficiency, due to an attenuation in androgen synthesis (e.g., during Sjögren's syndrome, menopause, aging, complete androgen-insensitivity syndrome [CAIS] and anti-androgen use), will lead to meibomian gland dysfunction and evaporative dry eye. The following studies were designed to test these predictions.

METHODS

Experimental procedures included clinical studies, animal models, and histological, biochemical, molecular biological, and biomedical engineering techniques.

RESULTS

Our results demonstrate that: (1) androgens regulate the meibomian gland. This tissue contains androgen receptor mRNA, androgen receptor protein within acinar epithelial cell nuclei, and Types 1 and 2 5alpha-reductase mRNAs. Moreover, androgens appear to modulate lipid production and gene expression in mouse and/or rabbit meibomian glands; and (2) androgen deficiency may lead to meibomian gland dysfunction, altered lipid profiles in meibomian gland secretions, tear film instability, and evaporative dry eye. Thus, we have found that anti-androgen therapy in men is associated with meibomian gland disease, a decreased tear film breakup time, and functional dry eye. Furthermore, we have discovered that androgen receptor dysfunction in women with CAIS is associated with meibomian gland changes and a significant increase in the signs and symptoms of dry eye. Of interest, we have also found that androgen deficiency is associated with significant and striking alterations in the neutral and polar lipid patterns of human meibomian gland secretions.

CONCLUSIONS

Our findings show that the meibomian gland is an androgen target organ and that androgen deficiency may promote meibomian gland dysfunction and evaporative dry eye. Overall, these results support our hypothesis that androgen deficiency may be an important etiologic factor in the pathogenesis of evaporative dry eye in women with Sjögren's syndrome.

Effect of Laser in situ Keratomileusis for Hyperopia on Tear Film and Ocular Surface

PURPOSE

To examine the effects of laser in situ keratomileusis (LASIK) for hyperopia on the tear film and ocular surface.

METHODS

A retrospective 12-month analysis of 88 eyes (88 participants) who had LASIK for hyperopia was performed. Participants were evaluated before and after (2 weeks, 1, 3, 6, and 12 months) surgery for dry eye symptoms (McMonnies Dry Eye Survey primary symptoms), tear film stability (fluorescein break-up time), tear volume (phenol red thread test), ocular surface staining (fluorescein), and conjunctival goblet cell density.

RESULTS

Chronic dry eye was experienced by 32% of participants; symptoms were significantly associated with female gender, preoperative dry eye symptoms, lower tear film stability after surgery, greater ocular surface staining after surgery, lower tear volume before and after surgery, and lower goblet cell densities after surgery. Regression rate 12 months after surgery was 32% and significantly associated with female gender, chronic dry eye symptoms, lower tear film stability after surgery, greater ocular surface staining before and after surgery, and lower tear volume before and after surgery.

CONCLUSIONS

Dry eye, particularly in females, is problematic after LASIK for hyperopia and is associated with refractive regression. Current methods for managing the tear film and ocular surface may not control LASIK-induced dry eye, particularly in some females during the first 6 months after surgery.

The pathology of dry eye

Homeostasis of the tear film involves delicate hormonal and neuronal regulatory mechanisms. The eye appears to be a target organ for sex hormones, particularly the androgens, as they modulate the immune system and trophic functions of the lacrimal glands and the functioning of the meibomian glands. The cornea, lacrimal glands, mucous cells, and meibomian glands are all richly innervated, indicating the importance of nervous regulation in their function. Parasympathetic, sympathetic, and sensory innervation play complex stimulatory or inhibitory roles, and neuronal pathways interact via complex surface results cascades. Abnormalities at any point in these pathways can cause overall dysregulation of lacrimal function. Whatever the initial causes of dry eye, chronic dryness of the ocular surface results in inflammatory reactions and gradual destruction of the lacrimal glands and conjunctival epithelium. Once dry eye disease has developed, inflammation is the key mechanism of ocular surface injury, as both the cause and consequence of cell damage. In practice, dry eye can be associated with Sjögren's syndrome, allergies, infection, blepharitis, and preservative-containing eye drops.

Sexual dimorphism and aromatase in the rat retina

The present study: (a) determined the effects of both pre- and early postnatal androgen hormonal manipulation on retinal thickness, (b) examined the presence of the aromatase enzyme by immunocytochemistry in retinal tissue and (c) quantified aromatase activity in the rat retina. The results suggest that retinal thickness is influenced by perinatal hormone manipulation via aromatizable androgens that have implications for the sex differences seen in visual information processing and performance.

Impact of antiandrogen treatment on the fatty acid profile of neutral lipids in human meibomian gland secretions

The purpose of this study was to determine whether the use of antiandrogen medications is associated with significant alterations in the fatty acid (FA) profiles of neutral lipids in human meibomian gland secretions. Meibomian gland secretions were obtained from both eyes of patients receiving antiandrogen therapy and from age-related controls. Samples were processed for high-performance liquid chromatography/mass spectrometry and an evaluation of the mass/charge ratios of neutral lipid FA. Our results demonstrate that antiandrogen therapy is associated with significant and consistent alterations in the mass/charge ratios of neutral lipid fractions of meibomian gland secretions. Patients taking antiandrogen medications had significant changes in the occurrence of numerous diglyceride, triglyceride, and wax/cholesterol ester FA products, compared with age-matched controls. Statistical analyses of data within groups demonstrated very high correlation coefficients, and cross-correlation analyses revealed characteristic shifts in FA patterns between groups. Our findings show that antiandrogen use is paralleled by significant changes in the FA profiles of neutral lipid fractions in meibomian gland secretions.

Androgens and dry eye in Sjögren's syndrome

Sjögren's syndrome is an extremely complex and currently incurable autoimmune disorder, which occurs primarily in females, and is associated with lacrimal gland inflammation, meibomian gland dysfunction, and severe dry eye. We hypothesize that androgen deficiency, which reportedly occurs in primary and secondary Sjögren's syndrome (e.g., systemic lupus erythematosus, rheumatoid arthritis), is a critical etiologic factor in the pathogenesis of dry eye syndromes. We further hypothesize that androgen treatment to the ocular surface will promote both lacrimal and meibomian gland function and alleviate both "aqueous-deficient" and "evaporative" dry eye. Our results demonstrate that androgens regulate both lacrimal and meibomian gland function, and suggest that topical androgen administration may serve as a safe and effective therapy for the treatment of dry eye in Sjögren's syndrome.