Identification of Steroidogenic Enzyme mRNAs in the Human Lacrimal Gland, Meibomian Gland, Cornea, and Conjunctiva

Inflammation mechanism and anti-inflammatory therapy of dry eye

Dry eye is a widespread chronic inflammatory disease that causes fatigue, tingling, burning, and other symptoms. Dry eye is attributed to rheumatic diseases, diabetes, hormone disorders, and contact lenses, which activate inflammatory pathways: mitogen-activated protein kinases (MAPK) and nuclear factor-B (NF-κB), promote macrophage inflammatory cell and T cell activation, and inflammation factors. Clinicians use a combination of anti-inflammatory drugs to manage different symptoms of dry eye; some of these anti-inflammatory drugs are being developed. This review introduces the dry eye inflammation mechanisms and the involved inflammatory factors. We also elucidate the anti-inflammatory drug mechanism and the detection limits.

Measurement of Anions in Tear Fluid Using Ion Chromatography

PURPOSE

Tear fluid (TF) contains a variety of electrolytes that exhibit a strong correlation with its osmotic pressure. These electrolytes are also related to the etiology of diseases on ocular surfaces such as dry eye syndromes and keratopathy. Although positive ions (cations) in TF have been investigated to understand their roles, negative ions (anions) have hardly been studied because applicable analytical methods are restricted to a few kinds. In this study, we established a method to analyze the anions involved in a sufficiently small amount of TF for in situ diagnosis of a single subject.

METHODS

Twenty healthy volunteers (10 men and 10 women) were recruited. Anions in their TF were measured on a commercial ion chromatograph (IC-2010, Tosoh, Japan). Tear fluid (5 μL or more) was collected from each subject with a glass capillary, diluted with 300 μL of pure water, and conveyed to the chromatograph. We successfully monitored the concentrations of bromide, nitrate, phosphate, and sulfate anions (Br - , NO 3- , HPO 42- , and SO 42- , respectively) in TF.

RESULTS

Br - and SO 42- were universally detected in all samples, whereas NO 3- was found in 35.0% and HPO 42- in 30.0% of them. The mean concentrations (mg/L) of each anion were Br - , 4.69 ± 0.96; NO 3- , 0.80 ± 0.68; HPO 42- , 17.48 ± 7.60; and SO 42- , 3.34 ± 2.54. As for SO 42- , no sex differences or diurnal variations were observed.

CONCLUSIONS

We established an efficient protocol to quantitate various inorganic anions involved in a small amount of TF using a commercially available instrument. This is the first step to elucidate the role of anions in TF.

Challenges and Opportunities in P450 Research on the Eye

Of the 57 cytochrome P450 enzymes found in humans, at least 30 have ocular tissues as an expression site. Yet knowledge of the roles of these P450s in the eye is limited, in part because only very few P450 laboratories expanded their research interests to studies of the eye. Hence the goal of this review is to bring attention of the P450 community to the eye and encourage more ocular studies. This review is also intended to be educational for eye researchers and encourage their collaborations with P450 experts. The review starts with a description of the eye, a fascinating sensory organ, and is followed by sections on ocular P450 localizations, specifics of drug delivery to the eye, and individual P450s, which are grouped and presented based on their substrate preferences. In sections describing individual P450s, available eye-relevant information is summarized and concluded by the suggestions on the opportunities in ocular studies of the discussed enzymes. Potential challenges are addressed as well. The conclusion section outlines several practical suggestions on how to initiate eye-related research. SIGNIFICANCE STATEMENT: This review focuses on the cytochrome P450 enzymes in the eye to encourage their ocular investigations and collaborations between P450 and eye researchers.

Etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO)

Primary acquired nasolacrimal duct obstruction, or PANDO, is a common adult lacrimal drainage disorder. The current treatment modality of dacryocystorhinostomy to bypass the obstructed nasolacrimal duct has excellent outcomes. However, the understanding of the disease etiopathogenesis needs to be revisited. There are not many studies that specifically assessed any hypothesis or ones that convincingly put forth the presumed or confirmed interpretations regarding the PANDO pathogenesis or the mechanisms or pathways involved therein. Histopathological evidence points to recurrent inflammation of the nasolacrimal duct, subsequent fibrosis, and the resultant obstruction. The disease etiopathogenesis is considered multifactorial. Several implicated suspects include anatomical narrowing of the bony nasolacrimal duct, vascular factors, local hormonal imbalance, microbial influence, nasal abnormalities, autonomic dysregulation, surfactants, lysosomal dysfunction, gastroesophageal reflux, tear proteins, and deranged local host defenses. The present work reviewed the literature on the etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO) to gain insights into the present state of the understanding and the high-value translational implications of precisely decoding the disease etiology.

The effects of female sex hormones on the human cornea across a woman's life cycle

The cornea is a hormone-responsive tissue that responds to changing levels of female sex hormones. This review focuses on the structural and functional changes in the human cornea associated with the hormonal milestones of menarche, pregnancy, and menopause, as well as consequences stemming from the use of exogenous sex hormones for fertility control and replacement. Articles were identified by searching PubMed without language or region restrictions. The primary outcomes evaluated were changes in central corneal thickness (CCT), intraocular pressure (IOP), and quality of the ocular tear film. The potential impact of hormone-associated changes on the diagnosis and surgical management of common eye diseases, as well as the potential use of sex hormones as therapeutic agents is also considered. Understanding the physiological effects of female sex hormones on the cornea is important because that knowledge can shape the management decisions physicians and women face about ocular health across their life stages.

Expression of Androgen and Estrogen Receptors in the Human Lacrimal Gland

Lacrimal gland dysfunction causes dry eye disease (DED) due to decreased tear production. Aqueous-deficient DED is more prevalent in women, suggesting that sexual dimorphism of the human lacrimal gland could be a potential cause. Sex steroid hormones are a key factor in the development of sexual dimorphism. This study aimed to quantify estrogen receptor (ER) and androgen receptor (AR) expression in the human lacrimal gland and compare it between sexes. RNA was isolated from 35 human lacrimal gland tissue samples collected from 19 cornea donors. AR, ERα, and ERβ mRNA was identified in all samples, and their expression was quantified using qPCR. Immunohistochemical staining was performed on selected samples to evaluate protein expression of the receptors. ERα mRNA expression was significantly higher than the expression of AR and ERβ. No difference in sex steroid hormone (SSH) receptor mRNA expression was observed between sexes, and no correlation was observed with age. If ERα protein expression is found to be concordant with mRNA expression, it should be investigated further as a potential target for hormone therapy of DED. Further research is needed to elucidate the role of sex steroid hormone receptors in sex-related differences of lacrimal gland structure and disease.

Does Menopausal Status Affect Dry Eye Disease Treatment Outcomes with OC-01 (Varenicline Solution) Nasal Spray? A Post Hoc Analysis of ONSET-1 and ONSET-2 Clinical Trials

INTRODUCTION

This study sought to compare the efficacy of OC-01 (varenicline solution) nasal spray for treatment of dry eye disease (DED) in postmenopausal women (PM+) versus women who were not postmenopausal (PM-).

METHODS

This was a post hoc subgroup analysis of data integrated from two prior randomized controlled clinical trials, ONSET-1 and ONSET-2. Women randomized to treatment with OC-01 (varenicline solution) nasal spray 0.03 mg or vehicle control (VC) whose self-reported menopausal status (PM+ versus PM-) was known were included. Outcomes included the treatment difference (the OC-01 [varenicline solution] nasal spray change from baseline [CFB] minus VC CFB) in Schirmer test score (STS, mm) with anesthesia and the eye dryness score (EDS) measured on a 100-mm visual analog scale (0 = no discomfort, 100 = maximal discomfort). Least-squares mean treatment differences were derived from analysis of covariance (ANCOVA) models.

RESULTS

Overall, 449 female participants in the ONSET-1 and ONSET-2 trials randomized to the OC-01 (varenicline solution) nasal spray 0.03 mg or VC groups were included in this analysis. The treatment-menopausal status interaction terms in the STS and EDS ANCOVA and logistic regression models were not statistically significant (p > 0.05), indicating consistency of treatment effect between the PM- and PM+ groups. The treatment difference in STS was similar in the PM- and PM+ groups (6.7 and 5.5 mm, respectively). The treatment difference in EDS was similar in the PM- and PM+ groups (- 5.5 and - 4.1, respectively).

CONCLUSIONS

OC-01 (varenicline solution) nasal spray demonstrated similar efficacy in promoting natural tear production and improving symptoms in both PM- and PM+ groups. As menopausal-related hormonal changes may be associated with more severe DED, these results may support OC-01 (varenicline solution) nasal spray as an effective treatment for DED in women regardless of presenting menopausal status.

TRIAL REGISTRATION

Post hoc subgroup analysis of data integrated from ONSET-1 (ClinicalTrials.gov identifier NCT03636061) and ONSET-2 (ClinicalTrials.gov identifier NCT04036292).

Analysis of sex steroids in human tears using LC-MS and GC-MS: Considerations and developments to improve method sensitivity and accuracy

Sex steroids play a role in regulation of tear film function and may exert their action locally at the ocular surface. However, measurement of sex steroids in tears is difficult due to small-volume tear samples and very low concentrations of the hormones. This short communication highlights what has been achieved to date in the analysis of tear sex steroids using ultra-performance LC-MS (UPLC-MS) as previously published, and reports further and more recent investigations toward optimising mass spectrometry method sensitivity and accuracy. The published UPLC-MS method successfully measured progesterone, androsterone glucuronide and 5α-androstane-3α,17β-diol in pooled basal tears of postmenopausal women, and fourteen sex steroid standards in methanol. Limitations included sub-optimal limits of detection (LOD) and lower limits of quantification (LLOQ) for some analytes (particularly oestrogens), exclusion of sample matrix effects and no use of internal standards. This update reports on further experiments carried out to improve sensitivity and accuracy. Sample matrix effects, internal standard spiking, and derivatisation with dansyl chloride and oximes were investigated. Dansylation significantly improved the LOD and LLOQ of oestrogens and their metabolites, by a factor of 10 for oestradiol and a factor of 5 for oestrone, but sensitivity of this updated method is not sufficient however for analysis of these oestrogens in human tears. Using gas chromatography-mass spectrometry (GC-MS) as an alternative technique to LC-MS, improved sensitivity for derivatised oestradiol is reported. This work demonstrates the need to develop higher sensitivity methods and points researchers towards specific MS ionisation techniques for future analysis of sex steroids in tears, in order to progress current understanding of the role of sex steroids in tear function and dry eye.

Sex Steroid Hormone Analysis in Human Tear Fluid Using a Liquid Chromatography-Mass Spectrometry Method

The marked sexual dimorphism prevalent in inflammatory/autoimmune diseases is mostly due to sex hormone actions. One common eye disease that disproportionately affects women is dry eye. Thus, our aim was to optimise our highly sensitive liquid chromatography-tandem mass spectrometry method for steroid hormone quantification in tear fluid (TF). We used tears and matched serum samples from 10 heathy individuals. Estrone, estradiol testosterone, progesterone, androstenedione, and dehydroepiandrosterone, were quantified with an HPLC coupled with a Triple Quad 5500 MS. Estrone was measured in 80% of female and 20% of male TF samples (mean ± SD, 68.9 ± 62.2 pmol/L), whereas estradiol was undetectable in tears. Progesterone was identified in half of the female tear samples (2.91 ± 3.47 nmol/L) but in none of the male samples, whereas testosterone was quantifiable only in male tears (0.24 ± 0.1 nmol/L). TF hormone levels were, on average, from 1.4% to 55% of systemic values. Estrone, progesterone, and testosterone levels in tears correlated with the matching serum samples (r = 0.82, 0.79, and 0.85, respectively), but androstenedione and dehydroepiandrosterone showed no correlations. Our LC-MS/MS method could detect five out of the six steroid hormones studied in individual human TF samples and could therefore be used to analyse the role of sex steroids in eye diseases.

Sex Hormones, Growth Hormone, and the Cornea

The growth and maintenance of nearly every tissue in the body is influenced by systemic hormones during embryonic development through puberty and into adulthood. Of the ~130 different hormones expressed in the human body, steroid hormones and peptide hormones are highly abundant in circulation and are known to regulate anabolic processes and wound healing in a tissue-dependent manner. Of interest, differential levels of sex hormones have been associated with ocular pathologies, including dry eye disease and keratoconus. In this review, we discuss key studies that have revealed a role for androgens and estrogens in the cornea with focus on ocular surface homeostasis, wound healing, and stromal thickness. We also review studies of human growth hormone and insulin growth factor-1 in influencing ocular growth and epithelial regeneration. While it is unclear if endogenous hormones contribute to differential corneal wound healing in common animal models, the abundance of evidence suggests that systemic hormone levels, as a function of age, should be considered as an experimental variable in studies of corneal health and disease.

Anterior pituitary, sex hormones, and keratoconus: Beyond traditional targets

"The Diseases of the Horny-coat of The Eye", known today as keratoconus, is a progressive, multifactorial, non-inflammatory ectatic corneal disorder that is characterized by steepening (bulging) and thinning of the cornea, irregular astigmatism, myopia, and scarring that can cause devastating vision loss. The significant socioeconomic impact of the disease is immeasurable, as patients with keratoconus can have difficulties securing certain jobs or even joining the military. Despite the introduction of corneal crosslinking and improvements in scleral contact lens designs, corneal transplants remain the main surgical intervention for treating keratoconus refractory to medical therapy and visual rehabilitation. To-date, the etiology and pathogenesis of keratoconus remains unclear. Research studies have increased exponentially over the years, highlighting the clinical significance and international interest in this disease. Hormonal imbalances have been linked to keratoconus, both clinically and experimentally, with both sexes affected. However, it is unclear how (molecular/cellular signaling) or when (age/disease stage(s)) those hormones affect the keratoconic cornea. Previous studies have categorized the human cornea as an extragonadal tissue, showing modulation of the gonadotropins, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Studies herein provide new data (both in vitro and in vivo) to further delineate the role of hormones/gonadotropins in the keratoconus pathobiology, and propose the existence of a new axis named the Hypothalamic-Pituitary-Adrenal-Corneal (HPAC) axis.

Association Between Dry Eye and Polycystic Ovary Syndrome: Subclinical Inflammation May Be Part of the Process

PURPOSE

To evaluate the changes in tear function in patients with polycystic ovary syndrome (PCOS) and establish whether there is a correlation between hormonal levels, novel hematologic biomarkers, and dry eye parameters.

MATERIAL AND METHOD

Forty-seven patients with PCOS and 43 age-matched patients with unexplained infertility were included in the control group. Follicle-stimulating hormone, luteinizing hormone, estradiol, thyroid-stimulating hormone, prolactin, dehydroepiandrosterone sulfate (DHEA-S), 17-OH progesterone, fasting and postprandial glucose, fasting insulin, and cholesterol metabolites were evaluated in both groups. In addition, the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio were obtained from a complete blood count. The Ocular Surface Disease Index (OSDI) questionnaire was administered, and all patients underwent tear break-up time (BUT) and Schirmer I tests. Bivariate correlations were investigated using Spearman correlation coefficient analysis.

RESULTS

The mean age of the PCOS group and the control group was 27.66±3.96 years and 29.28±6.83 years, respectively. Schirmer I test scores and BUT values were significantly lower and OSDI results were significantly higher in the PCOS group (P=0.003, P<0.001, and P=0.004). An inverse correlation was found between DHEA-S and BUT values in the PCOS group (r=-0.296, P=0.043). Similarly, a negative correlation was also present between NLR and BUT values in the PCOS group (r=-0.322, P=0.027).

CONCLUSIONS

Dry eye can be well established by sensitive tests in patients with PCOS. The severity of dry eye may be correlated with the level of inflammation and hyperandrogenism.

Differential gene expression of the healthy conjunctiva during the day

PURPOSE

To determine if there is diurnal variation in gene expression in normal healthy conjunctival cells.

METHODS

Bulbar conjunctival swab samples were collected from four healthy subjects in the morning and evening of the same day. The two swab samples were taken from one eye of each participant, with a minimum of five hours gap between the two samples. RNA was extracted and analysed using RNA sequencing (RNA-Seq).

RESULTS

A total of 121 genes were differentially expressed between the morning and the evening conjunctival samples, of which 94 genes were upregulated in the morning, and 27 genes were upregulated in the evening. Many of the genes that were upregulated in the morning were involved in defence, cell turnover and regulation of gene expression, while the genes upregulated in the evening were involved in signalling and mucin production.

CONCLUSIONS

This study has identified several genes whose expression changes over the course of the day. Knowledge of diurnal variations of conjunctival gene expression provides an insight into the regulatory status of the healthy eye and provides a baseline for examining changes during ocular surface disease.

Sex Hormones Related Ocular Dryness in Breast Cancer Women

Background: Dry eye syndrome (DES) is strictly connected to systemic and topical sex hormones. Breast cancer treatment, the subsequent hormonal therapy, the subsequent hyperandrogenism and the early sudden menopause, may be responsible for ocular surface system failure and its clinical manifestation as dry eye disease. This local dryness is part of the breast cancer iatrogenic dryness, which affects overall mucosal tissue in the fragile population of those with breast cancer. Methods: A literature review regarding the role of sex hormone changes and systemic hormonal replacement treatments (SHRT) in DES available on PubMed and Web of Science was made without any restriction of language. Results: Androgens exert their role on the ocular surface supporting meibomian gland function and exerting a pro-sebaceous effect. Estrogen seems to show a pro/inflammatory role on the ocular surface, while SHRT effects on dry eye are still not well defined, determining apparently contradictory consequences on the ocular surface homeostasis. The role of sex hormones on dry eye pathogenesis is most likely the result of a strict crosstalk between the protective androgens effects and the androgen-modulating effects of estrogens on the meibomian glands. Conclusions: Patients with a pathological or iatrogenic hormonal imbalance, such as in the case of breast cancer, should be assessed for dry eye disease, as well as systemic dryness, in order to restore their social and personal quality of life.

Prevalence of ocular surface disease symptoms in peri- and postmenopausal women

OBJECTIVE

The objective of the study was to determine the prevalence of ocular surface disease (OSD) symptoms and the possible existence of differences between peri- and postmenopausal women, based on the result of the Ocular Surface Disease Index (OSDI).

METHODS

A transversal observational study based on the results of an e-mail survey between October 2018 and January 2019 involving 1,947 women. The study was performed on a group of peri- and postmenopausal women aged between 45 and 79 years. The personal data in the survey included age, menopause status, age at menopause, prediagnosis of dry eye, undergoing dry eye treatment, and the OSDI questionnaire. Student's t test and Chi squared test were used to compare means or percentages between results on the survey and peri- and postmenopausal women. Finally, a univariate logistic regression was carried out to estimate the prevalence of OSD. The OSDI score is assessed on a scale of 0 to 100.

RESULTS

The mean age of the entire sample was 54.2 ± 6.8 years, with a mean age at menopause of 49.45 ± 4.02 years. The mean OSDI score was 29.2 ± 19.4, considered as moderate dry eye. The global prevalence of OSD symptoms was 64% (1,247/1,947), which increased significantly in postmenopausal women, being 66.8% (820/1,228) (P = 0.001). The probability of OSD symptoms prevalence increases with age (odds ratio: 1.02; 95% CI [1.01-1.03]). The greater the age at menopause, the lower the probability of OSD symptoms prevalence (odds ratio: 0.96 95% CI [0.93-0.99]).

CONCLUSIONS

Sixty-four percent of the pre- and postmenopausal women studied had OSD symptoms. There was a correlation between OSD symptoms and age, postmenopause, and earlier age at menopause, which was associated with an increased prevalence. : Video Summary:http://links.lww.com/MENO/A603.

A Phase II, Multicenter, Randomized, Placebo-Controlled, Double-Masked Trial of a Topical Estradiol Ophthalmic Formulation in Postmenopausal Women with Moderate-to-Severe Dry Eye Disease

INTRODUCTION

Dry eye disease (DED) is a multifactorial disorder of the ocular surface. The current phase II study was performed to assess the safety and dose regimen of a recently developed topical estradiol formulation for the treatment of DED.

METHODS

A total of 104 postmenopausal women suffering from moderate-to-severe DED were included. Topical 17-β-estradiol-3-phosphate eye drops were administered in three different dosage groups (group 1, 0.05% twice daily; group 2, 0.1% morning, vehicle in the evening; group 3, 0.1% twice daily) and vehicle twice daily as control group for a total period of 3 months. Clinical signs including Schirmer's test and corneal staining were assessed at baseline and at days 14, 30, 60, and 90. Symptoms of DED were measured using the symptom assessment in dry eye (SANDE) test at the same time points. Safety was assessed via frequency of adverse events.

RESULTS

Schirmer's test II wetting distance significantly increased in all four groups from baseline to day 90 without significant difference between groups (group 1, + 5.6 ± 6.7 mm/5 min; group 2, + 3.7 ± 4.2 mm/5 min; group 3, + 4.8 ± 4.5 mm/5 min; group 4, + 4.0 ± 5.3 mm/5 min). Statistical significance versus baseline was reached earlier in the treatment groups versus the control group. Corneal staining was significantly reduced after the 3-month treatment period with no significant difference between treatment groups. Staining of the inferior cornea, however, showed a significantly more pronounced decrease in the highest dose group compared to vehicle (p = 0.0463). Symptoms score as assessed with the SANDE test decreased at the end of the treatment period in all four groups. Estradiol eye drops showed a favorable safety profile.

CONCLUSION

Our results show that both estradiol eye drops and vehicle are safe and reduce signs and symptoms in postmenopausal women with moderate-to-severe DED. Although the study failed to reach the primary outcome to demonstrate a significant difference between the estradiol eye drops and vehicle in Schirmer's test, improvement occurred earlier in the active groups compared to the control group. The data of the current study will serve as a basis for a larger phase III study to establish a potential therapeutic effect of topical estradiol eye drops.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov registry NCT03821415.

Dihydrotestosterone suppression of proinflammatory gene expression in human meibomian gland epithelial cells

PURPOSE

We discovered that dihydrotestosterone (DHT) decreases the ability of lipopolysaccharide, a bacterial toxin, to stimulate the secretion of leukotriene B4, a potent proinflammatory mediator, by immortalized human meibomian gland epithelial cells (IHMGECs). We hypothesize that this hormone action reflects an androgen suppression of proinflammatory gene activity in these cells. Our goal was to test this hypothesis. For comparison, we also examined whether DHT treatment elicits the same effect in immortalized human corneal (IHC) and conjunctival (IHConj) ECs.

METHODS

Differentiated cells were cultured in media containing vehicle or 10 nM DHT. Cells (n = 3 wells/treatment group) were then processed for RNA isolation and the analysis of gene expression by using Illumina BeadChips, background subtraction, cubic spline normalization and Geospiza software.

RESULTS

Our results demonstrate that DHT significantly suppressed the expression of numerous immune-related genes in HMGECs, such as those associated with antigen processing and presentation, innate and adaptive immune responses, chemotaxis, and cytokine production. DHT also enhanced the expression of genes for defensin β1, IL-1 receptor antagonist, and the anti-inflammatory serine peptidase inhibitor, Kazal type 5. In contrast, DHT had no effect on proinflammatory gene expression in HCECs, and significantly increased 33 gene ontologies linked to the immune system in HConjECs.

CONCLUSIONS

Our findings support our hypothesis that androgens suppress proinflammatory gene expression in IHMGECs. This hormone effect may contribute to the typical absence of inflammation within the human meibomian gland.

Role of hydroxysteroid (17beta) dehydrogenase type 1 in reproductive tissues and hormone-dependent diseases

Abnormal synthesis and metabolism of sex steroids is involved in the pathogenesis of various human diseases, such as endometriosis and cancers arising from the breast and uterus. Steroid biosynthesis is a multistep enzymatic process proceeding from cholesterol to highly active sex steroids via different intermediates. Human Hydroxysteroid (17beta) dehydrogenase 1 (HSD17B1) enzyme shows a high capacity to produce the highly active estrogen, estradiol, from a precursor hormone, estrone. However, the enzyme may also play a role in other steps of the steroid biosynthesis pathway. In this article, we have reviewed the literature on HSD17B1, and summarize the role of the enzyme in hormone-dependent diseases in women as evidenced by preclinical studies.

[Modified meibography in malignant eyelid tumors of epithelial origin]

INTRODUCTION

Eyelid tumors can be diagnosed using various diagnostic techniques. However, capability of existing methods for determining the type and margins of the tumor at the preoperative stage remains insufficiently studied.

PURPOSE

To improve the noncontact infrared meibography technique and determine its diagnostic capabilities for studying structural changes in meibomian glands in malignant eyelid tumors of epithelial origin.

MATERIAL AND METHODS

The study included 49 people (66 eyelids), among which 21 (21 eyelids) with malignant eyelid tumors, 11 - with benign eyelid tumors (11 eyelids), and 17 (34 eyelids) comprised the control group. The mean age of patients was 64.8±1.56 years. Meibomian glands of the lower eyelids were photographed in infrared light. Receiver-operating characteristic (ROC) curves were constructed to estimate the sensitivity and specificity of the method.

RESULTS

Modified meibography showed 100% sensitivity and 90% specificity in the differential diagnosis of malignant and benign eyelid tumors in 32 patients. Unlike other methods, the modified meibography technique can clarify the margins of tumor growth, which is considered when planning the resection volume.

CONCLUSION

Modified meibography can indicate the margins of tumor invasion; it can be successfully used in the differential diagnostics of malignant eyelid tumors of epithelial origin and benign eyelid tumors.

Loss of β Epithelial Sodium Channel Function in Meibomian Glands Produces Pseudohypoaldosteronism 1-Like Ocular Disease in Mice

Human subjects with pseudohypoaldosteronism-1 because of loss-of-function mutations in epithelial sodium channel (ENaC) subunits exhibit meibomian gland (MG) dysfunction. A conditional βENaC MG knockout (KO) mouse model was generated to elucidate the pathogenesis of absent ENaC function in the MG and associated ocular surface disease. βENaC MG KO mice exhibited a striking age-dependent, female-predominant MG dysfunction phenotype, with white toothpaste-like secretions observed obstructing MG orifices at 7 weeks of age. There were compensatory increases in tear production but higher tear sodium and indexes of mucin concentration in βENaC MG KO mice. Histologically, MG acinar atrophy was observed with ductal enlargement and ductal epithelial hyperstratification. Inflammatory cell infiltration was observed in both MG and conjunctiva of βENaC MG KO mice. In older βENaC MG KO mice (5 to 11 months), significant ocular surface pathologies were noted, including corneal opacification, ulceration, neovascularization, and ectasia. Inflammation in MG and conjunctiva was confirmed by increased cytokine gene and protein expression and positive Ly-6B.2 immunostaining. Cell proliferation assays revealed lower proliferation rates of MG cells derived from βENaC MG KO than control mice, suggesting that βENaC plays a role in cell renewal of mouse MG. Loss of βENaC function resulted in MG disease and severe ocular surface damage that phenocopied aspects of human pseudohypoaldosteronism-1 MG disease and was sex dependent.

Local synthesis of sex hormones: are there consequences for the ocular surface and dry eye?

Sex hormones are associated with the physiology and pathophysiology of almost all organs in the body, as well as most diseases. Interest in the associations between sex hormones and ocular tissues has increased in recent years. Androgens may have a positive effect on dry eye, whereas the effects of oestrogen on ocular conditions remain unclear. Intracrinology, the local synthesis and metabolism of hormones that is unique to humans, is of relevance to the eye and may help to explain why studies of the relationship between oestrogens and dry eye signs and symptoms are inconclusive. Knowledge of the pathways of hormone formation and metabolism is crucial to understanding the pathogenesis of ocular disease including dry eye. This review examines the mechanisms of steroidal sex hormone biosynthesis and reviews the significance of locally produced sex hormones, with a focus on ocular surface tissues. Much of the current literature is based on animal studies, which may not be transferable to humans due to the absence of intracrine production in animals. A large proportion of the human studies investigate systemic hormone levels rather than local levels. There is subsequently a need for additional studies to provide a better understanding of the local production of sex hormones within the human eye and ocular surface and to clarify the relationships between ocular levels of sex hormones and conditions including dry eye.

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.

TFOS DEWS II pathophysiology report

The TFOS DEWS II Pathophysiology Subcommittee reviewed the mechanisms involved in the initiation and perpetuation of dry eye disease. Its central mechanism is evaporative water loss leading to hyperosmolar tissue damage. Research in human disease and in animal models has shown that this, either directly or by inducing inflammation, causes a loss of both epithelial and goblet cells. The consequent decrease in surface wettability leads to early tear film breakup and amplifies hyperosmolarity via a Vicious Circle. Pain in dry eye is caused by tear hyperosmolarity, loss of lubrication, inflammatory mediators and neurosensory factors, while visual symptoms arise from tear and ocular surface irregularity. Increased friction targets damage to the lids and ocular surface, resulting in characteristic punctate epithelial keratitis, superior limbic keratoconjunctivitis, filamentary keratitis, lid parallel conjunctival folds, and lid wiper epitheliopathy. Hybrid dry eye disease, with features of both aqueous deficiency and increased evaporation, is common and efforts should be made to determine the relative contribution of each form to the total picture. To this end, practical methods are needed to measure tear evaporation in the clinic, and similarly, methods are needed to measure osmolarity at the tissue level across the ocular surface, to better determine the severity of dry eye. Areas for future research include the role of genetic mechanisms in non-Sjögren syndrome dry eye, the targeting of the terminal duct in meibomian gland disease and the influence of gaze dynamics and the closed eye state on tear stability and ocular surface inflammation.

Meibomian glands, meibum, and meibogenesis

Meibum is a lipid-rich secretion that is produced by fully differentiated meibocytes in the holocrine Meibomian glands (MG) of humans and most mammals. The secretion is a part of a defense mechanism that protects the ocular surface from hazardous environmental factors, and from desiccation. Meibomian lipids that have been identified in meibum are very diverse and unique in nature. The lipid composition of meibum is different from virtually any other lipid pool found in the human body. In fact, meibum is quite different from sebum, which is the closest secretion that is produced by anatomically, physiologically, and biochemically related sebaceous glands. However, meibum of mice have been shown to closely resemble that of humans, implying similar biosynthetic mechanisms in MG of both species. By analyzing available genomic, immunohistochemical, and lipidomic data, we have envisioned a unifying network of enzymatic reactions that are responsible for biosynthesis of meibum, which we call meibogenesis. Our current theory is based on an assumption that most of the biosynthetic reactions of meibogenesis are catalyzed by known enzymes. However, the main features that make meibum unique - the ratio of identified classes of lipids, the extreme length of its components, extensive ω-hydroxylation of fatty acids and alcohols, iso- and anteiso-branching of meibomian lipids (e.g. waxes), and the presence of rather unique complex lipids with several ester bonds - make it possible that either the activity of known enzymes is altered in MG, or some unknown enzymes contribute to the processes of meibogenesis, or both. Studies are in progress to elucidate meibogenesis on molecular level.

Differential Effects of Hormones on Cellular Metabolism in Keratoconus In Vitro

Keratoconus (KC) is a corneal thinning disease with an onset commonly immediately post-puberty and stabilization by 40 to 50 years of age. The role of hormones in regulating corneal tissue structure in homeostatic and pathological conditions is unknown. Our group recently linked altered hormone levels to KC. Our current study sought to investigate and delineate the effects of exogenous hormones, such as androgen, luteotropin, and estrogen, on corneal stroma bioenergetics. We utilized our established 3D in vitro model to characterize the effects of DHEA, prolactin, 17β-estradiol on insulin-growth factor-1 and -2 (IGF-1, -2) signaling and metabolic function in primary corneal fibroblasts from healthy controls (HCFs) and KC patients (HKCs). Our data showed that exogenous DHEA significantly downregulated IGF-1 and its receptor in both HCFs and HKCs with HKCs showing consistently lower basal pentose phosphate flux. Prolactin caused no significant change in IGF-1 levels and an increase in IGF-2 in HKCs correlating with an increase in ATP and NADH levels. 17β-estradiol led to a significant upregulation in pentose phosphate flux and glycolytic intermediates in HCFs. Our results identified hormone-specific responses regulated in HKCs compared to HCFs revealing a novel role for hormones on bioenergetics in KC.

Expression of 3β-hydroxysteroid dehydrogenase in ovarian and uterine tissue during diestrus and open cervix cystic endometrial hyperplasia-pyometra in the bitch

The purpose of this study was to compare the expression of 3β-hydroxystreroid dehydrogenase (3β-HSD) in the uterus and ovary of healthy dogs and those with cystic endometrial hyperplasia and/or pyometra complex (CEH-pyometra). Eighteen female dogs were included in the study. Eleven bitches with open cervix CEH-pyometra were included in the CEH-pyometra group and seven diestrus bitches in the control group. For immunostaining a rabbit polyclonal, one raised against recombinant human type 2 (adrenal/gonadal) 3β-HSD was used. Progesterone (P4) concentrations were not statistically different between the groups. Strongly stained large interstitial cell groups in the ovarian medulla were observed particularly in CEH-pyometra group although these cells in the control group were weakly or moderately stained and existed singly or paired. The expressions of 3β-HSD in luminal epithelium (42.40 ± 22.40% vs. 18.42 ± 13.15%, P < 0.05) and glandular epithelium (32.80 ± 27.05% vs. 2.94 ± 7.79%, P < 0.01) of endometrium were significantly higher in CEH-pyometra group than those in the control group. The expression of 3β-HSD in CL was higher (29.38 ± 9.58% vs. 22.94 ± 4.97%) in CEH-pyometra group than that of control group although the differences were not significant (P > 0.05). Similarly, the significant increase in the expression of 3β-HSD in ovarian interstitial cells (33.86 ± 29.44 vs. 1.13 ± 2.97, P < 0.05) was found in CEH-pyometra group compared to the control group. The study revealed that 3β-HSD expression in the endometrium of canine CEH-pyometra was significantly high.

High Levels of 17β-Estradiol Are Associated with Increased Matrix Metalloproteinase-2 and Metalloproteinase-9 Activity in Tears of Postmenopausal Women with Dry Eye

Purpose. To determine the serum levels of sex steroids and tear matrix metalloproteinases (MMP) 2 and 9 concentrations in postmenopausal women with dry eye. Methods. Forty-four postmenopausal women with dry eye and 22 asymptomatic controls were enrolled. Blood was drawn and analyzed for serum levels of sex steroids and lipids. Then, the following tests were performed: tear collection, Ocular Surface Disease Index (OSDI) questionnaire, fluorescein tear film break-up time (TBUT), corneal fluorescein staining, Schirmer test, and conjunctival impression cytology. The conjunctival mRNA expression and tear concentrations of MMP-2 and MMP-9 were measured. Results. Serum 17β-estradiol levels were significantly higher in the dry eye subjects than in the controls (P = 0.03), whereas there were no significant differences in levels of testosterone, dehydroepiandrosterone sulfate (DHEA-S), and progesterone. Tear MMP-2 and MMP-9 concentrations (P < 0.001), as well as the MMP-9 mRNA expression in conjunctival samples (P = 0.02), were significantly higher in dry eye subjects than in controls. Serum 17β-estradiol levels were positively correlated with tear MMP-2 and MMP-9 concentrations and negatively correlated with Schirmer test values. Conclusions. High levels of 17β-estradiol are associated with increased matrix metalloproteinase-2 and metalloproteinase-9 activity in tears of postmenopausal women with dry eye.

Effects of Sex Hormones on Ocular Surface Epithelia: Lessons Learned From Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine abnormality in women of reproductive age. Although its clinical consequences have been known for a long time to extend beyond the reproductive system, with type-2 diabetes and obesity being the most common, the involvement of the ocular surface in PCOS has been described only more recently. The ocular surface is a morphofunctional unit comprising eyelid margin, tear film, cornea, and conjunctiva. Increasing evidence indicates that these structures are under a sex hormone control and relevant diseases such as ocular allergy and dry eye are often caused by alterations in circulating or local steroid hormones levels. Novel treatments targeting sex hormone receptors on ocular surface epithelial cells are also being developed. In this review we aim to describe the current knowledge on the effects of sex hormones at the ocular surface, with a special focus on the effects of androgen imbalance in PCOS.

The estrogenic retina: The potential contribution to healthy aging and age-related neurodegenerative diseases of the retina

These last two decades have seen an explosion of clinical and epidemiological research, and basic research devoted to envisage the influence of gender and hormonal fluctuations in the retina/ocular diseases. Particular attention has been paid to age-related disorders because of the overlap of endocrine and neuronal dysfunction with aging. Hormonal withdrawal has been considered among risk factors for diseases such as glaucoma, diabetic retinopathy and age-related macular disease (AMD), as well as, for Alzheimer's disease, Parkinson's disease, or other neurodegenerative disorders. Sex hormones and aging have been also suggested to drive the incidence of ocular surface diseases such as dry eye and cataract. Hormone therapy has been approached in several clinical trials. The discovery that the retina is another CNS tissue synthesizing neurosteroids, among which neuroactive steroids, has favored these studies. However, the puzzling data emerged from clinical, epidemiological and experimental studies have added several dimensions of complexity; the current landscape is inherently limited to the weak information on the influence and interdependence of endocrine, paracrine and autocrine regulation in the retina, but also in the brain. Focusing on the estrogenic retina, we here review our knowledge on local 17β-oestradiol (E2) synthesis from cholesterol-based neurosteroidogenic path and testosterone aromatization, and presence of estrogen receptors (ERα and ERβ). The first cholesterol-limiting step and the final aromatase-limiting step are discussed as possible check-points of retinal functional/dysfunctional E2. Possible E2 neuroprotection is commented as a group of experimental evidence on excitotoxic and oxidative retinal paradigms, and models of retinal neurodegenerative diseases, such as glaucoma, diabetic retinopathy and AMD. These findings may provide a framework to support clinical studies, although further basic research is needed.

Ocular Mucosal Immunity

Mucosal immunity defends the ocular surface against antigenic challenge and microbial invasion. The principal effector site is the lacrimal gland, where immunoglobulin A (IgA) antibodies are produced. Nasal-associated lymphoid tissue and posterior cervical lymph nodes function as major inductive sites for tear IgA responses. Neural connections and systemic hormones maintain the integrity and function of the ocular surface. Neuroenzyme activities in the lacrimal gland are influenced by ocular infections, leading to reduced expression of acetylcholine and modulation of receptors on acinar cells and on plasma cells, thereby decreasing fluid and immunoglobulin secretion. T lymphocyte-dependent responses result in production of interleukin-4 in lacrimal glands, thereby influencing cholinergic enzyme activity affecting immune processes and lacrimal physiology. Furthermore, neuropeptides released into lymphoid structures or inflamed tissues are chemotactic for antigen-presenting cells and affect their interactions with T cells. Thus, in developing therapeutic approaches for treating dry-eye conditions and vaccination strategies to elicit protective ocular mucosal immune responses, the entire lacrimal functional unit should be considered.

Sex-steroid imbalance in females and dry eye

Dry eye (DE) is a multifactorial disorder of the ocular surface unit that results in eye discomfort, visual disturbance and ocular surface damage. It is one of the most common complaints in daily ophthalmic practice. The risk of DE increases with age in both sexes, while its incidence is higher among females. In addition, the condition of menopause in aging women may also contribute to DE onset or worsening as a consequence of an overall hormonal imbalance. Sex hormones play a key role in ocular surface physiology and they impact differently on ocular surface tissues. Reduced estrogen levels were historically thought to be responsible in age-related DE onset but more recent investigations have reconsidered the role of androgens that are present and exert a protective function on the ocular surface. Hormone levels themselves, withdrawal changes in hormone levels, and the changes in hormone-receptor responsiveness are all important factors but it remains to be fully elucidated how estrogen or androgen insufficiency act alone or together in a combined imbalance or interplay to raise the risk of disease. The purpose of this review is to briefly outline current scientific evidence on the influence of androgens and estrogens, on the Lachrymal and Meibomian glands and on ocular surface epithelia including conjunctival goblet cells during reproductive and menopausal periods. The role of sex steroids is also discussed in relation to the pathogenesis of different forms of DE and Sjogren's syndrome (SS). The impact of systemic hormone therapy (HT) in DE post-menopausal women still appears as a controversial issue, despite the many clinical studies. Finally, the outcomes of topical applications of steroid-based products are summarized, underlying the need for potential (tear) biomarker(s) in the rationale of DE-targeted therapy.

The neurobiology of the meibomian glands

This article compiles research regarding the neuroanatomy of the meibomian glands and their associated blood vessels. After a review of meibomian gland morphology and regulation via hormones, a case for innervation is made based on anatomical findings whereby the nerves lack a myelin sheath and Schwann cells. The localization and co-localization of dopamine beta-hydroxylase, tyrosine hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, calcitonin gene-related peptide, and substance P are explored with emphasis on differences that exist between species. The presence of the various neuropeptides/neurotransmitters adjacent to the meibomian gland versus the vasculature associated with the meibomian gland is documented so that conclusions can be made with regard to direct and indirect effects. Research regarding the presence of receptors and receptor proteins for these neuropeptides is documented. Evidence supporting the influence of certain neurotransmitters and/or neuropeptides on the meibomian gland is given based on research that correlates changes in meibomian gland morphology and/or tear film with changes in neurotransmitter and/or neuropeptide presence. Conclusions are drawn related to direct and indirect regulation and differences between the various nervous systems.

Sex hormones and the dry eye

The greater prevalence of dry eye in women compared to men suggests that sex hormones may have a role in this condition. This review aims to present evidence for how sex hormones may affect the ocular structures involved in the production, regulation and maintenance of the normal tear film. It is hypothesised that hormone changes alter the homeostasis of the ocular surface and contribute to dry eye. Androgens impact on the structure and function of the meibomian and lacrimal glands and therefore androgen deficiency is, at least in part, associated with the aetiology of dry eye. In contrast, reports of the effects of oestrogen and progesterone on these ocular structures and on the conjunctiva are contradictory and the mechanisms of action of these female-specific sex hormones in the eye are not well understood. The uncertainty of the effects of oestrogen and progesterone on dry eye symptoms is reflected in the controversial relationship between hormone replacement therapy and the signs and symptoms of dry eye. Current understanding of sex hormone influences on the immune system suggests that oestrogen may modulate a cascade of inflammatory events, which underlie dry eye.

Objective image analysis of the meibomian gland area

Aims

To evaluate objectively the meibomian gland area using newly developed software for non-invasive meibography.

Methods

Eighty eyelids of 42 patients without meibomian gland loss (meiboscore=0), 105 eyelids of 57 patients with loss of less than one-third total meibomian gland area (meiboscore=1), 13 eyelids of 11 patients with between one-third and two-thirds loss of meibomian gland area (meiboscore=2) and 20 eyelids of 14 patients with two-thirds loss of meibomian gland area (meiboscore=3) were studied. Lid borders were automatically determined. The software evaluated the distribution of the luminance and, by enhancing the contrast and reducing image noise, the meibomian gland area was automatically discriminated. The software calculated the ratio of the total meibomian gland area relative to the total analysis area in all subjects. Repeatability of the software was also evaluated.

Results

The mean ratio of the meibomian gland area to the total analysis area in the upper/lower eyelids was 51.9±5.7%/54.7±5.4% in subjects with a meiboscore of 0, 47.7±6.0%/51.5±5.4% in those with a meiboscore of 1, 32.0±4.4%/37.2±3.5% in those with a meiboscore of 2 and 16.7±6.4%/19.5±5.8% in subjects with a meiboscore of 3.

Conclusions

The meibomian gland area was objectively evaluated using the developed software. This system could be useful for objectively evaluating the effect of treatment on meibomian gland dysfunction.

Influence of aromatase absence on the gene expression and histology of the mouse meibomian gland

PURPOSE

We hypothesize that aromatase, an enzyme that controls estrogen biosynthesis, plays a major role in the sex-related differences of the meibomian gland. To begin to test this hypothesis, we examined the influence of aromatase absence, which completely eliminates estrogen production, on glandular gene expression and histology in male and female mice.

METHODS

Meibomian glands were obtained from adult, age-matched wild-type (WT) and aromatase knockout (ArKO) mice. Tissues were processed for histology or the isolation of total RNA, which was analyzed for differentially expressed mRNAs by using microarrays.

RESULTS

Our results show that aromatase significantly influences the expression of more than a thousand genes in the meibomian gland. The nature of this effect is primarily sex-dependent. In addition, the influence of aromatase on sex-related differences in gene expression is predominantly genotype-specific. However, many of the sex-related variations in biological process, molecular function, and cellular component ontologies, as well as in KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, are remarkably similar between WT and ArKO mice. The loss of aromatase activity has no obvious effect on the histology of meibomian glands in male or female mice.

CONCLUSIONS

Our findings demonstrate that aromatase has a significant impact on gene expression in the meibomian gland. The nature of this influence is sex-dependent and genotype-specific; however, many of the sex-related variations in gene ontologies and KEGG pathways are similar between WT and ArKO mice. Consequently, it appears that aromatase, and by extension estrogen, do not play a major role in the sex-related differences of the mouse meibomian gland.

Molecular basis for involvement of CYP1B1 in MYOC upregulation and its potential implication in glaucoma pathogenesis

CYP1B1 has been implicated in primary congenital glaucoma with autosomal recessive mode of inheritance. Mutations in CYP1B1 have also been reported in primary open angle glaucoma (POAG) cases and suggested to act as a modifier of the disease along with Myocilin (MYOC). Earlier reports suggest that over-expression of myocilin leads to POAG pathogenesis. Taken together, we propose a functional interaction between CYP1B1 and myocilin where 17β estradiol acts as a mediator. Therefore, we hypothesize that 17β estradiol can induce MYOC expression through the putative estrogen responsive elements (EREs) located in its promoter and CYP1B1 could manipulate MYOC expression by metabolizing 17β estradiol to 4-hydroxy estradiol, thus preventing it from binding to MYOC promoter. Hence any mutation in CYP1B1 that reduces its 17β estradiol metabolizing activity might lead to MYOC upregulation, which in turn might play a role in glaucoma pathogenesis. It was observed that 17β estradiol is present in Human Trabecular Meshwork cells (HTM) and Retinal Pigment Epithelial cells (RPE) by immunoflouresence and ELISA. Also, the expression of enzymes related to estrogen biosynthesis pathway was observed in both cell lines by RT-PCR. Subsequent evaluation of the EREs in the MYOC promoter by luciferase assay, with dose and time dependent treatment of 17β estradiol, showed that the EREs are indeed active. This observation was further validated by direct binding of estrogen receptors (ER) on EREs in MYOC promoter and subsequent upregulation in MYOC level in HTM cells on 17β estradiol treatment. Interestingly, CYP1B1 mutants with less than 10% enzymatic activity were found to increase the level of endogenous myocilin in HTM cells. Thus the experimental observations are consistent with our proposed hypothesis that mutant CYP1B1, lacking the 17β estradiol metabolizing activity, can cause MYOC upregulation, which might have a potential implication in glaucoma pathogenesis.

Lateral canthal anatomy: a review

The anatomy of the lateral canthus is analogous to that of the medial canthus, but with a less defined structure. Although the lateral canthal tendon occupies the major part of the lateral canthal anatomy, the lateral rectus capsulopalpebral fascia and other structures also play a significant role. Appropriate comprehension and consideration of the lateral canthal anatomy enable safe and effective performance in the lateral canthal surgeries. In this review, we present the lateral canthal anatomy along with updated topics. We discuss the lateral canthal tendon, lateral orbital thickening, lateral palpebral raphe, lateral canthal muscle, lateral rectus capsulopalpebral fascia, lateral check ligament, lateral retinaculum, and orbitomalar ligament.

Estrogen negatively regulates epithelial wound healing and protective lipid mediator circuits in the cornea

Estrogen receptors (ERs) are expressed in leukocytes and in every ocular tissue. However, sex-specific differences and the role of estradiol in ocular inflammatory-reparative responses are not well understood. We found that female mice exhibited delayed corneal epithelial wound closure and attenuated polymorphonuclear (PMN) leukocyte responses, a phenotype recapitulated by estradiol treatment both in vivo (topically in male mice) and in vitro (corneal epithelial cell wound healing). The cornea expresses 15-lipoxygenase (15-LOX) and receptors for lipoxin A(4) (LXA(4)), which have been implicated in an intrinsic lipid circuit that regulates corneal inflammation and wound healing. Delayed epithelial wound healing correlated with lower expression of 15-LOX in the regenerated epithelium of female mice. Estradiol in vitro and in vivo down-regulated epithelial 15-LOX expression and LXA(4) formation, while estradiol abrogation of epithelial wound healing was completely reversed by treatment with LXA(4). More important, ERβ and ERα selectively regulated epithelial wound healing, PMN cell recruitment, and activity of the intrinsic 15-LOX/LXA(4) circuit. Our results demonstrate for the first time a sex-specific difference in the corneal reparative response, which is mediated by ERβ and ERα selective regulation of the epithelial and PMN 15-LOX/LXA(4) circuit. These findings may provide novel insights into the etiology of sex-specific ocular inflammatory diseases.

Lipidomics of human Meibomian gland secretions: Chemistry, biophysics, and physiological role of Meibomian lipids

Human Meibomian gland secretions (MGS) are a complex mixture of diverse lipids that are produced by Meibomian glands that are located in the upper and the lower eyelids. During blinking, MGS are excreted onto the ocular surface, spread and mix with aqueous tears that are produced by lachrymal glands, and form an outermost part of an ocular structure called "the tear film" (TF). The main physiological role of TF is to protect delicate ocular structures (such as cornea and conjunctiva) from desiccating. Lipids that are produced by Meibomian glands are believed to "seal" the aqueous portion of TF by creating a hydrophobic barrier and, thus, retard evaporation of water from the ocular surface, which enhances the protective properties of TF. As lipids of MGS are interacting with underlying aqueous sublayer of TF, the chemical composition of MGS is critical for maintaining the overall stability of TF. There is a consensus that a small, but important part of Meibomian lipids, namely polar, or amphiphilic lipids, is of especial importance as it forms an intermediate layer between the aqueous layer of TF and its upper (and much thicker) lipid layer formed mostly of very nonpolar lipids, such as wax esters and cholesteryl esters. The purpose of this review is to summarize the current knowledge on the lipidomics of human MGS, including the discussions of the most effective modern analytical techniques, chemical composition of MGS, biophysical properties of Meibomian lipid films, and their relevance for the physiology of TF. Previously published results obtained in numerous laboratories, as well as novel data generated in the author's laboratory, are discussed. It is concluded that despite a substantial progress in the area of Meibomian glands lipidomics, there are large areas of uncertainty that need to be addressed in future experiments.

[Sex hormones and dry eye]

Among ophthalmic diseases dry eye in its various forms, represents an entity with one of the highest prevalences and at the same time the lowest chance for causal therapy. Since some years there is growing evidence that sex hormones play a key role in the formation and course of the disease and thus provide potentially promising approaches for therapy. The objective of this article is to briefly outline current scientific knowledge on the relationship between androgens, estrogens,and progesterones on the one hand and the lacrimal gland and Meibomian glands respectively.

Meibomian gland alterations in polycystic ovary syndrome

PURPOSE

Polycystic ovary syndrome (PCOS) is an endocrinopathy characterized by chronic anovulation and hyperandrogenism where hyperinsulinemia can be seen. Hormonal changes can affect meibomian gland function. In this study, we evaluated tear function in PCOS.

MATERIALS AND METHODS

Twenty-seven women having PCOS and 22 normal individuals aged between 18-42 years were enrolled in the study. Patients were asked about dry eye symptoms. Schirmer test, tear film breakup time, and rose Bengal staining were performed. Conjunctival brush cytology specimens were obtained and goblet cell count was done.

RESULTS

Dry eye symptoms were more frequent in subjects with PCOS (p=0.025). Mean breakup time was shorter in women with PCOS (p=0.034). Schirmer test results, rose Bengal staining scores, and goblet cell count were not different between groups (p=0.48, p=0.18, p=0.82, respectively).

CONCLUSION

Meibomian gland function and tear film lipid layer can be affected in cases with PCOS.

Androgen influence on cholesterogenic enzyme mRNA levels in the mouse meibomian gland

PURPOSE

We tested our hypothesis that testosterone increases the meibomian gland gene expression of numerous enzymes in the cholesterol biosynthetic pathway.

METHODS

Meibomian glands were obtained from castrated mice treated with vehicle or testosterone for 2 weeks. Tissues were processed for the analysis of selected mRNAs by real-time PCR.

RESULTS

Our research demonstrates that testosterone stimulates a significant increase in the mRNA levels of mevalonate kinase, phosphomevalonate kinase, mevalonate pyrophosphate decarboxylase, isopentenyl pyrophosphate isomerase, geranylgeranyl pyrophosphate synthase, squalene epoxidase, lanosterol synthase, lanosterol demethylase, and Delta 7-sterol reductase.

CONCLUSIONS

Our findings indicate that androgens may promote cholesterol biosynthesis in the meibomian gland.