Can tetracycline antibiotics duplicate the ability of azithromycin to stimulate human meibomian gland epithelial cell differentiation?

The effect of airborne particulate matter 2.5 (PM2.5) on meibomian gland

Exposure to particulate matters in air pollution of 2.5 μm or less (PM2.5) was associated with loss of meibomian glands. The aim of this study was to verify that PM2.5 could directly impact meibomian gland epithelial cells and damage their function. To investigate the impact of PM2.5 on meibomian gland, immortalized human meibomian gland epithelial cells were treated with various concentrations of PM2.5in vitro. Meibomian gland cell microstructure, cell viability, expression of proliferating cell nuclear antigen and IL-1β, and intracellular accumulation of acidic vesicles were measured by transmission electron microscopy, cell counting, Western blot and LysoTracker staining, respectively. To further study the effect of PM2.5in vivo, male C57BL/6J mice were treated with 5 mg/ml PM2.5 or vehicle for 3 months. Corneal fluorescein staining and ocular examinations were done before and after the treatment. Eyelids tissues were processed for morphological studies, immunostaining and Oil Red O staining. Our data suggest that exposure to PM2.5 caused significant meibomian gland dropout, clogged gland orifice and increased corneal fluorescein staining that were consistent with the clinical presentations of meibomian gland dysfunction. Prominent changes in the morphology and ultrastructure of meibomian glands was observed with PM2.5 treatment. PM2.5 promoted ductal keratinization, inhibited cell proliferation, induced cell apoptosis and increased Interleukin-1β production in meibomian gland epithelial cells. This study may explain the association between PM2.5 exposure and meibomian gland dropout observed in clinic. PM2.5 resuspension instillation could be used to induce a meibomian gland dysfunction animal model.

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.

Recent advances in drug treatments for dry eye disease

INTRODUCTION

Dry eye disease (DED) is a common ocular condition with a significant impact on patients' quality of life. Conventional treatments include behavioral changes, tear substitutes, and anti-inflammatory agents; however, recent advances in the understanding of DED pathogenesis have opened the way to the development of novel treatment strategies able to target several pathways involved in the onset and persistence of DED.

AREAS COVERED

Literature search was conducted on PubMed and Scopus around the term 'dry eye disease' and others involving its pathophysiology and therapeutic strategy. The primary focus was on recent drugs approved by FDA or under investigation in phase 3 clinical trials. Google and ClinicalTrials.gov were used for obtaining information about the status of FDA approval and ongoing clinical trials.

EXPERT OPINION

Due to its multifaced pathogenesis, DED management is often challenging, and patients' needs are frequently unmet. Recently, several novel treatments have been either FDA-approved or studied in late-phase trials. These novel drugs target-specific biological components of the ocular surface and reduce inflammation and ocular pain. Additionally, new drug delivery systems allow for increased bioavailability, improve effective dosing, and minimize ocular side effects. These advances in drug therapies show real promise for better management of DED patients.

A comparative review of evaporative dry eye disease and meibomian gland dysfunction in dogs and humans

Dry eye disease is a complex ophthalmic disorder that consists of two main subtypes, aqueous deficient dry eye (ADDE) and evaporative dry eye disease (EDED). Due to the complex underlying physiology, human dry eye disease can be difficult to model in laboratory animal species. Thus, the identification and characterization of a spontaneous large animal model of dry eye disease is desirable. Dogs have been described as an ideal spontaneous model of ADDE due to the similar pathophysiology between dogs and humans. Recently, EDED and meibomian gland dysfunction (MGD) have been increasingly recognized and reported in dogs. These reports on EDED and MGD in dogs have identified similarities in pathophysiology, clinical presentations, and diagnostic parameters to humans with the comparable disorders. Additionally, the tests that are used to diagnose EDED and MGD in humans are more easily applicable to dogs than to laboratory species due to the comparable globe sizes between dogs and humans. The reported response of dogs to EDED and MGD therapies are similar to humans, suggesting that they would be a valuable preclinical model for the development of additional therapeutics. Further research and clinical awareness of EDED and MGD in dogs would increase their ability to be utilized as a preclinical model, improving the positive predictive value of therapeutics for EDED and MGD in both humans and dogs.

Nonantimicrobial Actions of Macrolides: Overview and Perspectives for Future Development

Macrolides are among the most widely prescribed broad spectrum antibacterials, particularly for respiratory infections. It is now recognized that these drugs, in particular azithromycin, also exert time-dependent immunomodulatory actions that contribute to their therapeutic benefit in both infectious and other chronic inflammatory diseases. Their increased chronic use in airway inflammation and, more recently, of azithromycin in COVID-19, however, has led to a rise in bacterial resistance. An additional crucial aspect of chronic airway inflammation, such as chronic obstructive pulmonary disease, as well as other inflammatory disorders, is the loss of epithelial barrier protection against pathogens and pollutants. In recent years, azithromycin has been shown with time to enhance the barrier properties of airway epithelial cells, an action that makes an important contribution to its therapeutic efficacy. In this article, we review the background and evidence for various immunomodulatory and time-dependent actions of macrolides on inflammatory processes and on the epithelium and highlight novel nonantibacterial macrolides that are being studied for immunomodulatory and barrier-strengthening properties to circumvent the risk of bacterial resistance that occurs with macrolide antibacterials. We also briefly review the clinical effects of macrolides in respiratory and other inflammatory diseases associated with epithelial injury and propose that the beneficial epithelial effects of nonantibacterial azithromycin derivatives in chronic inflammation, even given prophylactically, are likely to gain increasing attention in the future. SIGNIFICANCE STATEMENT: Based on its immunomodulatory properties and ability to enhance the protective role of the lung epithelium against pathogens, azithromycin has proven superior to other macrolides in treating chronic respiratory inflammation. A nonantibiotic azithromycin derivative is likely to offer prophylactic benefits against inflammation and epithelial damage of differing causes while preserving the use of macrolides as antibiotics.

Therapie des Trockenen Auges

Die Therapie des Trockenen Auges stellt eine schwierige Aufgabe für den behandelnden Augenarzt dar. Fortschritte in unserem Verständnis der Risikofaktoren, der Ätiologie und Pathophysiologie des Trockenen Auges haben zu einer Weiterentwicklung der Behandlungsstrategien geführt. Vor Beginn der Therapie ist die korrekte Zuordnung in eine wässrig-muzinöse Tränenfilmdysfunktion (Mindersekretion), in eine lipidbedingte Tränenfilmdysfunktion (hyperevaporative Form durch eine abnormen Meibom-Drüsen-Physiologie) oder in eine variable Kombination wichtig. Unter Berücksichtigung aktueller Empfehlungen der DOG, des BVA und des TFOS DEWS II Unterausschusses wurde ein Behandlungsalgorithmus abgeleitet, der ein schrittweises Vorgehen je nach Schweregrad der Erkrankung darstellt.

Evidence of Polyphenols Efficacy against Dry Eye Disease

Dry eye disease is a multifactorial pathology compromising the quality of life of patients, resulting in significant damage of the ocular surface and discomfort. The current therapeutical strategies are not able to definitively resolve the underlying causes and stop the symptoms. Polyphenols are promising natural molecules that are receiving increasing attention for their activity/effects in counteracting the main pathologic mechanisms of dry eye disease and reducing its symptoms. In the present review, a deep literature search focusing on the main polyphenols tested against dry eye disease was conducted, analyzing related in vitro, in vivo, and clinical studies to provide a comprehensive and current review on the state of the art. Polyphenols present multiple effects against dry eye diseases-related ocular surface injury. In particular, the observed beneficial effects of polyphenols on corneal cells are the reduction of the pathological processes of inflammation, oxidative stress, and apoptosis and modulation of the tear film. Due to numerous studies reporting that polyphenols are effective and safe for treating the pathological mechanisms of this ocular surface disease, we believe that future studies should confirm and extend the evidence of polyphenols efficacy in clinical practice against dry eye disease and help to develop new ophthalmic drug(s).

Efficacy of Azithromycin Eyedrops for Individuals With Meibomian Gland Dysfunction-Associated Posterior Blepharitis

PURPOSE

To examine the safety and efficacy of azithromycin eyedrops in Japanese individuals with meibomian gland dysfunction (MGD)-associated posterior blepharitis.

METHODS

Individuals with MGD-associated posterior blepharitis who visited the Itoh Clinic, Saitama, Japan, were randomly assigned to receive azithromycin (1%) eyedrops (AZM group, 16 eyes of 16 patients) or preservative-free artificial tears (control group, 20 eyes of 20 patients) for 2 weeks. All subjects also applied a warming eyelid compress twice per day. Subjective symptoms (Standardized Patient Evaluation of Eye Dryness [SPEED] score), lipid layer thickness (LLT) and interferometric pattern of the tear film, plugging and vascularity of the lid margin, noninvasive break-up time of the tear film (NIBUT) and fluorescein-based break-up time of the tear film (TBUT), corneal-conjunctival fluorescein staining score, tear meniscus height, meibum grade, meiboscore, tear osmolarity, and Schirmer test value were determined before and after treatment. Side effects of treatment were also recorded.

RESULTS

In the AZM group, SPEED score, LLT, interferometric pattern, plugging and vascularity of the lid margin, NIBUT, TBUT, meibum grade, and tear osmolarity were significantly improved after treatment compared with baseline. The SPEED score, interferometric pattern, plugging, vascularity, meibum grade, and tear osmolarity were also significantly improved after treatment in the AZM group compared with the control group. Common side effects in the AZM group were transient eye irritation and blurred vision.

CONCLUSION

Azithromycin eyedrops improved eyelid inflammation, the quality and quantity of the lipid layer of the tear film, and tear film stability. Such eyedrops thus seem to be a safe and effective treatment for MGD-associated posterior blepharitis.

The Role of Topical Azithromycin in the Treatment of Meibomian Gland Dysfunction

PURPOSE

The efficacy of topical azithromycin (AZ) supplementation to systemic AZ has not been studied. This study evaluates the efficacy of topical AZ supplementation to systemic AZ, warm compresses, artificial tears, and lid scrubs for the treatment of meibomian gland dysfunction (MGD).

METHODS

Eighty-five patients with stage 4 MGD were enrolled in the study. The patients enrolled into the study were divided into 2 groups. Group 1 comprised 55 patients who received preservative-free topical 1.5% AZ administered as a unit dose, and group 2 comprised 30 patients who did not receive topical AZ. Both groups were prescribed artificial tear eye drops and systemic AZ. Fluorescein tear film breakup time (TBUT), corneal staining, Ocular Surface Disease Index (OSDI) symptom scores, and meibum quality were evaluated at baseline and after 1 and 3 months.

RESULTS

The mean age of patients in group 1 was 48.3 ± 13.4 years (25 men and 30 women) and in group 2 was 50.7 ± 10.2 years (12 men and 18 women). After treatment at the first and third month, group 1 showed significant improvement in mean TBUT, mean corneal staining score, meibum quality, and mean OSDI scores compared with baseline (P < 0.05). In group 2, only the OSDI score and meibum quality improved significantly after treatment compared with baseline (P < 0.05).

CONCLUSIONS

These results demonstrate clinically and statistically greater improvement in MGD-associated signs and symptoms with the addition of topical AZ to the systemic treatment.

The Role of Hypoxia-Inducible Factor 1α in the Regulation of Human Meibomian Gland Epithelial Cells

Purpose

We recently discovered that a hypoxic environment is beneficial for meibomian gland (MG) function. The mechanisms underlying this effect are unknown, but we hypothesize that it is due to an increase in the levels of hypoxia-inducible factor 1α (HIF1α). In other tissues, HIF1α is the primary regulator of cellular responses to hypoxia, and HIF1α expression can be induced by multiple stimuli, including hypoxia and hypoxia-mimetic agents. The objective of this study was to test our hypothesis.

Methods

Human eyelid tissues were stained for HIF1α. Immortalized human MG epithelial cells (IHMGECs) were cultured for varying time periods under normoxic (21% O2) or hypoxic (1% O2) conditions, in the presence or absence of the hypoxia-mimetic agent roxadustat (Roxa). IHMGECs were then processed for the analysis of cell number, HIF1α expression, lipid-containing vesicles, neutral and polar lipid content, DNase II activity, and intracellular pH.

Results

Our results show that HIF1α protein is present in human MG acinar epithelial cells in vivo. Our findings also demonstrate that exposure to 1% O2 or to Roxa increases the expression of HIF1α, the number of lipid-containing vesicles, the content of neutral lipids, and the activity of DNase II and decreases the pH in IHMGECs in vitro.

Conclusions

Our data support our hypothesis that the beneficial effect of hypoxia on the MG is mediated through an increased expression of HIF1α.

Evaluation of Cell Harvesting Techniques to Optimize Lipidomic Analysis from Human Meibomian Gland Epithelial Cells in Culture

The lipidomic analysis of immortalized human meibomian gland epithelial cells (HMGECs) has been proposed as a preclinical model to study meibomian gland dysfunction. An in vitro study was conducted to evaluate neutral lipid recovery following three harvesting techniques and to identify candidate lipid biomarkers of HMGECs. HMGECs were cultured in serum-containing media for two days to promote lipid production. Cells were either harvested by 0.25% trypsin–ethylenediaminetetraacetic acid (EDTA), harvested by 10 mM EDTA, or simultaneously harvested and extracted by 2:1 chloroform–methanol (CM). After extraction by a modified Folch technique, the nonpolar phase was processed and infused into a TripleTOF 5600 mass spectrometer (Sciex, Framingham, MA, USA) with electrospray ionization. MS and MS/MS^all spectra were acquired. Nonpolar cholesteryl esters (CEs) were consistently detected in all samples, while wax esters were not. Only small differences in two out of twenty CEs were detected between harvesting methods. CM yielded less CE18:1 than the other methods but greater CE20:4 than the trypsin–EDTA method (p < 0.05 for all). Similar to human meibum, very long-chain CEs with carbon number (n_c) ≥ 24 were detected in all samples and may serve as HMGEC lipid biomarkers. Further work is needed to address the absence of wax esters. Overall, the three harvesting methods are reasonably equivalent, though CM promotes much better efficiency and is recommended for higher throughput.

Eicosapentaenoic acid (EPA) activates PPARγ signaling leading to cell cycle exit, lipid accumulation, and autophagy in human meibomian gland epithelial cells (hMGEC)

PURPOSE

The purpose of this study was to access the ability of the natural PPAR agonist, eicosapentaenoic acid (EPA), to activate PPAR gamma (γ) signaling leading to meibocyte differentiation in human meibomian gland epithelial cell (hMGEC).

METHODS

HMGEC were exposed to EPA, alone and in combination with the specific PPARγ antagonist, T0070907, to selectively block PPARγ signaling. Expression of PPARγ response genes were evaluated by qPCR. Effect on cell cycle was evaluated using Ki-67 labelling and western blots. During differentiation, autophagy was monitored using the Autophagy Tandem Sensor (ATS) and LysoTracker. Lipid accumulation was characterized by Stimulated Raman Scattering microscopy (SRS) and neutral lipid staining in combination with ER-Tracker, LysoTracker, and ATS. Autophagy was also investigated using western blotting. Seahorse XF analysis was performed to monitor mitochondrial function.

RESULTS

EPA specifically upregulated expression of genes related to lipid synthesis and induced cell cycle exit through reduced cyclin D1 expression and increased p21 and p27 expression. EPA also induced accumulation of lipid droplets in a time and dose dependent manner (P < 0.05) by specific PPARγ signaling. Lipid analysis identified both de novo synthesis and extracellular transport of lipid to form lipid droplets that were localized to the ER. PPARγ signaling also induced activation of AMPK-ULK1 signaling and autophagy, while inhibition of autophagy induced mitochondrial crisis with no effect on lipid accumulation.

CONCLUSIONS

EPA induces meibocyte differentiation through PPARγ activation that is characterized by cell cycle exit, de novo and transported lipid accumulation in the ER, and autophagy.

Systematic review and meta-analysis of treating meibomian gland dysfunction with azithromycin

To systematically review studies of managing meibomian gland dysfunction (MGD) with azithromycin and pool clinical outcomes to show its effectiveness. Eligible studies were retrieved from five main electronic databases. Symptom score was the primary outcome, while clinical signs and objective measurements were secondary outcomes. Pooled rates for adverse events were also calculated. Improvements in each outcome after administering either oral azithromycin (OA) or topical azithromycin (TA) were pooled and measured by standard mean difference (SMD) to show the overall effectiveness. Then the effectiveness was sub-grouped by TA and OA. In addition, pooled outcomes after administering TA and oral doxycycline (OD) were compared with assess their effectiveness. Finally, 18 eligible studies were included. The overall pooled symptom scores were significantly reduced after administering both TA and OA [P < 0.0001; SMD = 1.54 (95% CI: 1.15–1.92)]. Similarly, the overall combined eyelid signs, plugging of the meibomian gland, meibum quality, and tear secretion were also distinctly improved. However, significant improvements for tear break-up time (TBUT) and corneal staining (CS) were achieved by TA (TBUT: P = 0.02; CS: P = 0.02) but not by OA (TBUT: P = 0.08; CS: P = 0.14). The pooled adverse event rates for TA and OA were 25% and 7%, respectively. Moreover, TA was comparable to OD to treat MGD regarding symptom score, TBUT and tear secretion. This study showed that MGD could be treated effectively with oral or topical azithromycin by improving symptoms, clinical signs, and stabilization of tear film. Topical azithromycin seemed to be superior over oral azithromycin or doxycycline in improving the quality of tear film in the short term.

Biguanides Induce Acute de novo Lipogenesis in Human Primary Sebocytes

Introduction

Acne arises during puberty, in part, due to elevated hormones and growth factors which stimulate de novo lipogenesis (DNL) in primary sebocytes to significantly increase sebum production. Oral isotretinoin is an effective acne therapy, reducing sebum production through inducing apoptosis in sebocytes. However, isotretinoin is teratogenic and has additional unwanted side effects, including an initial acne flare-up, which limits its utility. The biguanide, metformin has been found to alleviate severe acne in women with polycystic ovary syndrome (PCOS) through normalization of their insulin and androgen hormone levels. Metformin’s broader effectiveness to improve acne in non-PCOS populations lacks significant clinical support. In an effort to determine whether biguanides directly affect sebogenesis, we investigated their ability to alter DNL in cell-based assays in vitro.

Methods

De novo lipogenesis was measured in human primary sebocytes using [14C]-acetate labeling. Lipid species analysis was performed by extracting newly synthesized lipids and subjecting them to thin layer chromatography. Gene expression changes in sebocytes were identified through qPCR analysis of isolated RNA. Metabolic parameters including oxygen consumption rate, lactate production and activation of adenosine monophosphate-dependent protein kinase (AMPK) were assessed in human primary sebocytes.

Results

Using human primary sebocytes, we found that biguanides, isotretinoin and azithromycin induced an acute dose and time-dependent increase in [14C]-acetate labeling of neutral lipids, while AICAR, an AMPK activator, inhibited this DNL response. Biguanides did not activate AMPK in sebocytes, however, they significantly reduced oxygen consumption rate and increased lactate production. Treatment with biguanides, but not isotretinoin, significantly upregulated ACSS2 gene expression in primary sebocytes and showed synergism with lipogenic activators to induce DNL genes.

Discussion

These changes are consistent with an acute increase in sebocyte lipogenesis and support the potential of biguanides to cause an initial flare-up in patients suffering from severe acne.

Efficacy of azithromycin 1.5% eyedrops vs oral doxycycline in meibomian gland dysfunction: a randomized trial

PURPOSE

To determine the efficacy of azithromycin 1.5% eyedrops compared with oral doxycycline in patients with moderate to severe meibomian gland dysfunction (MGD).

METHODS

This prospective randomized trial included 169 participants with newly diagnosed moderate to severe MGD. Participants were randomly assigned to treatment with azithromycin 1.5% eyedrops (n = 85) twice daily for 2 days then once daily until 4 weeks or oral doxycycline (n = 84) 100 mg twice daily for 4 weeks. Signs and symptoms of MGD were evaluated at baseline and 4 weeks later. The percentages of participants with improvement in meibum quality were assessed as a primary outcome. Secondary outcomes were MGD-related symptoms, meibum expressibility, Oxford ocular surface staining score, tear film break up time (TBUT), and drug side effects.

RESULTS

Although there were significant improvements in all outcomes in both groups, there was no between-group differences in the percentages of participants with improved meibum quality (P = 0.80), MGD-related symptoms (P > 0.05), meibum expressibility (P = 0.92), Oxford ocular surface staining score (P = 0.59), and TBUT (P = 0.99). Five (5.88%) participants in azithromycin group and four (4.76%) participants in doxycycline group discontinued medications due to drug side effects (P = 0.75).

CONCLUSIONS

Both azithromycin 1.5% eyedrops and oral doxycycline significantly improved signs and symptoms in patients with moderate to severe MGD. Both azithromycin 1.5% eyedrops and oral doxycycline showed no difference in term of improved signs and symptoms of MGD as well as drug side effects that lead to discontinuation of medication.

Hypoxia: A breath of fresh air for the meibomian gland

PURPOSE

Optimal meibomian gland (MG) function is critically important for the health and wellbeing of the ocular surface. We hypothesize that low oxygen (O₂) conditions promote the function of human MG epithelial cells (HMGECs) and that human MGs exist in a relatively hypoxic environment. The purpose of this study was to test our hypotheses.

METHODS

We used human and mouse eyelid segments, and immortalized human MG epithelial cells (IHMGECs) in our studies. To evaluate oxygen (O₂) levels in the mouse MG and vicinity, we injected pimonidazole (pimo), a hypoxia marker, before sacrifice. Human eyelid samples were stained with the hypoxia marker glucose transporter 1 (Glut-1). To determine the effect of low O₂ levels on IHMGECs, we cultured cells under proliferating and differentiating conditions in both normoxic (21% O₂) and hypoxic (3% O₂) conditions for 5-15 days. IHMGECs were evaluated for cell number, neutral lipid content, lysosome accumulation, expression of biomarker proteins and DNase II activity.

RESULTS

Our results demonstrate that human and mouse MGs, but not the surrounding connective tissue, exist in a relatively hypoxic environment in vivo. In addition, our findings show that hypoxia does not influence IHMGEC numbers in basal or proliferating culture conditions, but does stimulate the expression of SREBP-1 in differentiating IHMGECs. Hypoxia also significantly increased DNase II activity, and apparently IHMGEC terminal differentiation.

CONCLUSIONS

Our Results support our hypotheses, and indicate that relative hypoxia promotes MG function.

An eye for azithromycin: review of the literature

Azithromycin is used widely in clinical practice and recently it is available in topical solution for ophthalmic use. The purpose of the current publication is to summarize the newest information on azithromycin’s clinical usefulness over ocular diseases. A PubMed (National Library of Medicine) and a ScienceDirect search was conducted using the key phrases ‘azithromycin’, ‘meibomian’, ‘blepharitis’, ‘trachoma’, ‘toxoplasmosis’ from 2010 to 2017. Articles were limited to articles published in English or at least having an English abstract. There were no restrictions on age, ethnicity, or geographic locations of patients. Topical azithromycin was found effective and safe in various ocular surface infections, in meibomian gland dysfunction and in trachoma. Also, it may substitute fluoroquinolones in corneal UV cross-linking. The World Health Organization targets for trachoma elimination are being reached only after 3 years of annual mass drug administration. Oral azithromycin can participate in combination regiments for toxoplasmosis, mainly because of its very good safety profile and may play a significant role in toxoplasmosis in pregnancy. Azithromycin is one of the safest antibiotics, well tolerated, and with special pharmacokinetic properties. Also, it is characterized by a broad antimicrobial spectrum. Azithromycin is efficacious for the treatment of a lot of ocular diseases and may be included as monotherapy or in combination therapy in new treatment protocols for more ocular infections. However, more research is needed to determine this.

The Effect of Solithromycin, a Cationic Amphiphilic Drug, on the Proliferation and Differentiation of Human Meibomian Gland Epithelial Cells

PURPOSE

We previously discovered that azithromycin (AZM) acts directly on immortalized human meibomian gland epithelial cells (IHMGECs) to stimulate their lipid and lysosome accumulation and overall differentiation. We hypothesize that this phospholipidosis-like effect is due to AZM's cationic amphiphilic drug (CAD) nature. If our hypothesis is correct, then other CADs (e.g., solithromycin [SOL]) should be able to duplicate AZM's action on IHMGECs. Our purpose was to test this hypothesis.

MATERIALS AND METHODS

IHMGECs were cultured in the presence of vehicle or SOL (2, 10, or 20 µg/ml) for up to 7 days under proliferating or differentiating conditions. Positive (epidermal growth factor and bovine pituitary extract for proliferation; AZM for differentiation) and negative (vehicle) controls were included with the experiments. IHMGECs were evaluated for cell number, neutral lipid content, and lysosome accumulation.

RESULTS

Our results demonstrate that SOL induces a rapid and dose-dependent increase in the accumulation of neutral lipids and lysosomes in HMGECs. The lysosomal effects were most prominent with the 10 and 20 µg/ml doses, and occurred earlier (i.e., 1 day) with SOL than with the AZM (10 µg/ml) control. The effects of SOL and AZM on IHMGEC differentiation were essentially the same after 3 days of culture. SOL did not influence the proliferation of HMGECs during a 7-day time period.

CONCLUSIONS

Our results support our hypothesis that SOL, a CAD, is able to reproduce AZM's impact on lysosome and lipid accumulation, as well as the differentiation, of HMGECs. The effect of SOL on lysosome appearance was faster than that of AZM.

Clinical efficacy of combined topical 0.05% cyclosporine A and 0.1% sodium hyaluronate in the dry eyes with meibomian gland dysfunction

AIM

To investigate the efficacy of combined topical 0.05% cyclosporine A (CsA; Restasis^®, Allergan pharmaceuticals, USA) and 0.1% sodium hyaluronate treatment in dry eyes with meibomian gland dysfunction (MGD).

METHODS

In a retrospective analysis, 53 patients (106 eyes) with MGD were enrolled and performed lid warm massage for 10min daily and be instilled preservative free sodium hyaluronate 0.1% eye drops 4 times daily. Patients were divided into subjects treated with topical 0.05% CsA and preservative free sodium hyaluronate vehicle (experimental group, n=74 eyes) and subjects treated with the preservative free sodium hyaluronate vehicle (control group, n=32 eyes). They were evaluated at baseline and 1, 2, and 3mo for subjective symptoms and objective signs including tear film break-up time (tBUT), Schirmer test, corneal staining (CS) score, lid margin telangiectasia (LMT), meibomian gland secretion (MGS), and conjunctival injection (CI).

RESULTS

In the short-term treatment, the experimental group showed a statistically significant improvement in the ocular surface disease index (OSDI; P<0.001), tBUT (P=0.004), Schirmer test score (P=0.008) and LMT (P=0.021) by repeated measure ANOVA. Additionally, mean changes from baseline in OSDI (P<0.001), tBUT (P=0.001), Schirmer test score (P=0.029), CS score (P=0.047), LMT (P=0.002), CI (P=0.030) were improved better in the experimental group than in the control group at 3mo. However, there was no significant difference between the two groups in MGS (P=0.67).

CONCLUSION

In dry eyes with MGD, 0.05% CsA improves the tear film stability as well as subjective ocular discomfort, and is effective in controlling lid margin inflammation.

Update in Current Diagnostics and Therapeutics of Dry Eye Disease

Dry eye disease (DED) represents a heterogeneous group of conditions with tear film insufficiency and signs and/or symptoms of ocular surface irritation. The clinical manifestations of DED can be highly variable; hence the diagnosis is often based on a combination of symptoms, signs, and clinical tests, given that any one of these alone would miss a significant number of patients. Similarly, the treatment must often be tailored to each patient by targeting the specific mechanisms involved in his or her disease. The purpose of this review is to summarize recent advances that have allowed us to better recognize, categorize, and treat patients with DED. The most notable new diagnostic tests in DED are tear film osmolarity, inflammatory biomarkers, and meibomian gland imaging. Therapeutically, anti-inflammatory therapy, meibomian gland heating and expression, and scleral contact lenses are some of the latest options available for treating DED.

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.

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.

Do Cyclosporine A, an IL-1 Receptor Antagonist, Uridine Triphosphate, Rebamipide, and/or Bimatoprost Regulate Human Meibomian Gland Epithelial Cells?

PURPOSE

Researchers have hypothesized that treatment with cyclosporine A (CyA), interleukin-1 receptor antagonists (IL-1RA; e.g., anakinra), P2Y2 receptor agonists (e.g., uridine triphosphate; UTP), and rebamipide may alleviate human meibomian gland dysfunction (MGD) and/or dry eye disease. Investigators have also proposed that prostaglandin analogues (e.g., bimatoprost) may induce MGD. Our goal was to determine whether these compounds directly influence human meibomian gland epithelial cell (HMGEC) function.

METHODS

Multiple concentrations of each compound were tested for effects on immortalized (I) HMGEC morphology and survival. Nontoxic dosages were used for our studies. Immortalized HMGEC were cultured in the presence of vehicle, CyA, IL-1RA, UTP, rebamipide, or bimatoprost for up to 6 days in various media. Experiments included positive controls for proliferation (epidermal growth factor and bovine pituitary extract), differentiation (azithromycin), and signaling pathway activation (insulin-like growth factor 1). Cells were analyzed for neutral lipid staining, lysosome accumulation, lipid composition, and phosphatidylinositol-3-kinase/Akt (AKT), phosphorylation.

RESULTS

Our findings demonstrate that CyA, IL-1RA, UTP, rebamipide, and bimatoprost had no effect on the proliferation; neutral lipid content; lysosome number; or levels of free cholesterol, triglycerides, or phospholipids in IHMGECs. Cylosporine A, IL-1RA, rebamipide, and bimatoprost significantly reduced the phosphorylation of AKT, as compared to control. Of interest, tested doses of CyA above 8 nM killed the IHMGECs.

CONCLUSIONS

Our results show that CyA, IL-1RA, UTP, rebamipide, and bimatoprost do not influence the proliferation or differentiation of IHMGEC. However, with the exception of UTP, these compounds do decrease the activity of the AKT signaling pathway, which is known to promote cell survival.

Influence of Omega 3 and 6 Fatty Acids on Human Meibomian Gland Epithelial Cells

PURPOSE

Oral supplementation with omega 3 (ω-3) and/or 6 (ω-6) fatty acids (FAs) has been reported to alleviate the signs and symptoms of dry eye disease and to improve the expressibility and quality of meibum, in patients with meibomian gland dysfunction. We tested our hypothesis that these FA effects may reflect a direct FA action on human meibomian gland epithelial cells.

METHODS

Immortalized human meibomian gland epithelial cells (IHMGECs) were cultured with ω-3, ω-6, or both FAs together for up to 7 days in the presence or absence of serum. After FA exposure, cells were analyzed for lipid expression, lysosome content, and proliferative ability.

RESULTS

Our research shows that ω-3 and ω-6 stimulate the accumulation of small neutral lipid-containing vesicles, but not lysosomes, in IHMGECs. This vesicular effect was associated with a 2.4- to 3.7-fold increase in the cellular content of triglycerides after ω-3 and ω-6 treatment, respectively. The combination of both FAs together also enhanced triglyceride levels. Of interest, culture of IHMGECs with ω-3 and azithromycin, a known inducer of IHMGEC differentiation, led to a significantly greater amount of total neutral lipids, relative to that found with azithromycin alone. Cellular exposure to the FAs did not alter the expression of free or esterified cholesterol, or phospholipids. Further, these FAs, alone or together, prevented the proliferation of IHMGECs in serum-free, but not serum-containing, media.

CONCLUSIONS

Our findings support our hypothesis and demonstrate that ω-3 and ω-6 can act directly on IHMGECs to influence the quality and quantity of intracellular lipids.

Treatment Practices and Outcomes of Meibomian Gland Dysfunction at a Tertiary Center in Southern India

OBJECTIVE

To describe the current treatment practices for meibomian gland dysfunction (MGD) at a tertiary eye center, together with the subjective outcomes and compliance behaviors of patients.

METHODS

This retrospective cohort study reviewed medical records for MGD severity grading, treatment prescribed, and follow-up schedule. In addition, participants were surveyed to gauge subjective outcomes and treatment adherence.

RESULTS

Eight hundred ten patients were diagnosed with "MGD" or "meibomitis" and had a total of 14 different treatment combinations prescribed. In 3.0% of cases, there was no treatment specified. As MGD severity increased, it became more likely that management would be applied and this was also associated with significantly longer treatment durations (P=0.02) and shorter follow-up periods (P<0.001). Posttreatment subjective outcomes and treatment adherence surveys had a response rate of 36.7% and 24.1% respectively. Overall, 53.5% reported sustained improvement, 40.7% no improvement, and 5.7% experienced temporary relief. Although no treatment regimen seemed to be more efficacious than others, patients showed greater adherence when using topical reagents compared with lid hygiene measures (P≤0.002).

CONCLUSION

Clinicians, in this large tertiary eye center, use a wide range of treatment regimens to manage MGD. This suggests the need for development of standard management protocols. Whether alone, or in combination, no MGD treatment significantly improved subjective symptoms, a result that may be influenced by compliance behaviors. Use of topical reagents (eye drops or ointment) seemed to be associated with the best compliance. Future focus on more effective MGD treatments is needed to improve practical outcomes.

PPARγ Regulates Mouse Meibocyte Differentiation and Lipid Synthesis

PURPOSE

Previous reports suggest that age-related meibomian gland atrophy is associated with decreased expression of the lipid-sensitive nuclear receptor, PPARγ. The purpose of this study was to identify the role of PPARγ in modulating meibocyte lipid synthesis.

METHODS

Cytoplasmic and nuclear fractions from meibomian glands of young (2M) and old (2Y) C57Bl6 mice were probed using antibodies specific for PPARγ. Mouse meibocytes were cultured, immortalized using a SV40 lentiviral vector, and evaluated for lipid synthesis using LipidTox staining and CARS/Raman microspectroscopy. Lipid synthesizing clones were tested for effects of PPARγ agonist, rosiglitazone, on lipid synthesis and PPARγ localization, post-translational modification and induction of PPARγ response genes.

RESULTS

The cytoplasmic fraction in young mice contained both 50 and 72 kDa PPARγ bands that were absent or reduced by 75% in older mice, respectively. Cultured meibocytes produced neutral lipid containing equal amounts of wax and cholesterol esters, similar to mouse meibum. Addition of rosiglitazone (10-50 μM) significantly increased lipid production (P<.05) in meibocytes, associated with SUMO1 sumoylation and cytoplasmic accumulation of the 72 kDa PPARγ. Rosiglitazone also increased the localization of PPARγ to the cytoplasm and up-regulated of PPARγ, ADP and ADFP mRNA.

CONCLUSIONS

This study confirms the loss of cytoplasmic/vesicular PPARγ localization in older, atrophic mouse meibomian glands. Furthermore, PPARγ stimulates lipid synthesis in mouse meibocytes, associated with PPARγ sumoylation and translocation to the cytoplasm. Taken together these data suggest that lipid synthesis in older mice is down regulated by a PPARγ mediated pathway.

Comparison of therapeutic effects of topical azithromycin solution and systemic doxycycline on posterior blepharitis

AIM

To compare the effect of azithromycin drop and doxycycline capsule on treatment of posterior blepharitis.

METHODS

Fifty patients (100 eyes) with moderate posterior blepharitis, randomly divided into two therapeutic groups; all the patients got warm eyelid compress and massage three times a day for 3wk. In addition the first group got azithromycin 1% drop, twice daily for 1wk and then one drop daily for 2wk. The second group got oral doxycycline 100 mg daily for 3wk. At the end of the research, patients' signs and symptoms were compared together. ANOVA, Chi-square and Mann-Whitney tests were used for statistical analysis.

RESULTS

Topical therapy with azithromycin and oral therapy with doxycycline relieved signs and symptoms after 3wk. There were no significant differences between symptoms healing rate and foreign body sensation healing in these two groups (P>0.05). However, azithromycin drop was more effective in reduction of eye redness and doxycycline was more effective in meibomian glands plugging healing and reducing the corneal staining.

CONCLUSION

Topical azithromycin could have similar effects as oral doxycycline on posterior blepharitis in improving subjective symptoms. However, doxycycline can reduce objective signs such as ocular surface staining and meibomian gland plugging more than azithromycin.