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International Journal of Molecular... Aug 2023The main function of exocrine Meibomian glands (MGs) is to produce a lipid-rich secretion called meibum which plays a critical role in maintaining the ocular surface...
The main function of exocrine Meibomian glands (MGs) is to produce a lipid-rich secretion called meibum which plays a critical role in maintaining the ocular surface homeostasis of humans and most mammals. The chemical composition of meibum, and its quantity produced by MGs, largely determine whether it can fulfill its role successfully. Aging was frequently associated with the onset of various MG-related pathologies. The goal of this study was to determine how aging affects the chemical composition and quantity of meibum in mice, and identify possible molecular markers of aging. Unbiased, untargeted and targeted lipidomic evaluation of mouse MG lipids was conducted using liquid chromatography-high-resolution mass spectrometry, and the results were analyzed using Principal Component, Orthogonal Projections to Latent Structures Discriminant, and Partial Least Square Discriminant Analyses. We found that aging leads to dysregulation of lipid metabolism in MGs, changing the ratios of major classes of MG lipids (such as wax esters, triacylglycerols, and phospholipids) in a progressive manner. Several lipid species that belong to these groups of MG lipids are proposed as clear markers of aging in a mouse model.
Topics: Humans; Animals; Mice; Lipid Metabolism; Meibomian Glands; Aging; Biomarkers; Phospholipids; Mammals
PubMed: 37686319
DOI: 10.3390/ijms241713512 -
Mucosal Immunology Jun 2022The eye is a sensory organ exposed to the environment and protected by a mucosal tissue barrier. While it shares a number of features with other mucosal tissues, the... (Review)
Review
The eye is a sensory organ exposed to the environment and protected by a mucosal tissue barrier. While it shares a number of features with other mucosal tissues, the ocular mucosal system, composed of the conjunctiva, Meibomian glands, and lacrimal glands, is specialized to address the unique needs of (a) lubrication and (b) host defense of the ocular surface. Not surprisingly, most challenges, physical and immunological, to the homeostasis of the eye fall into those two categories. Dry eye, a dysfunction of the lacrimal glands and/or Meibomian glands, which can both cause, or arise from, sensory defects, including those caused by corneal herpes virus infection, serve as examples of these perturbations and will be discussed ahead. To preserve vision, dense neuronal and immune networks sense various stimuli and orchestrate responses, which must be tightly controlled to provide protection, while simultaneously minimizing collateral damage. All this happens against the backdrop of, and can be modified by, the microorganisms that colonize the ocular mucosa long term, or that are simply transient passengers introduced from the environment. This review will attempt to synthesize the existing knowledge and develop trends in the study of the unique mucosal and immune elements of the ocular surface.
Topics: Humans; Dry Eye Syndromes; Meibomian Glands; Lacrimal Apparatus; Conjunctiva; Mucous Membrane; Tears
PubMed: 36002743
DOI: 10.1038/s41385-022-00551-6 -
Experimental Eye Research Oct 2017Meibomian glands secrete meibum, which gives rise to the lipid layer of the tear film and thereby prevents excessive evaporation of tear fluid. Meibomian gland... (Review)
Review
Meibomian glands secrete meibum, which gives rise to the lipid layer of the tear film and thereby prevents excessive evaporation of tear fluid. Meibomian gland dysfunction (MGD) is a major causative condition of evaporative dry eye, which is more common than the aqueous-deficient type of dry eye. Noninvasive meibography relies on infrared light and an infrared-sensitive camera to reveal the morphology of meibomian glands in both the upper and lower eyelids, whereas tear interferometry allows both qualitative and quantitative evaluation of the lipid layer of the tear film. These two techniques not only provide valuable clinical information related to dry eye but also allow clinical evaluation of MGD. Tear interferometry also has the potential to distinguish the condition of the tear film between normal individuals and dry eye patients. Furthermore, combined evaluation of the noninvasive breakup time of the tear film and the interferometric fringe pattern as determined by tear interferometry allows classification of the subtype of dry eye disease.
Topics: Diagnostic Techniques, Ophthalmological; Dry Eye Syndromes; Humans; Interferometry; Meibomian Glands; Optical Imaging; Photography; Tears
PubMed: 28950939
DOI: 10.1016/j.exer.2017.06.010 -
Indian Journal of Ophthalmology Apr 2023An algorithm for automated segmentation of meibomian glands from infrared images obtained using a novel prototype infrared hand-held imager has been proposed in this... (Observational Study)
Observational Study
PURPOSE
An algorithm for automated segmentation of meibomian glands from infrared images obtained using a novel prototype infrared hand-held imager has been proposed in this study. Meibomian gland dysfunction (MGD) is quantified in terms of five clinically relevant metrics. A comparison of these metrics in patients with MGD has been presented against a sample of the normative healthy population.
METHODS
This is a prospective cross-sectional observational study. Patients presenting to the clinics were enrolled after written informed consent. The everted eyelids of 200 eyes of patients (of which 100 were healthy and 100 were diagnosed with MGD) were imaged using a prototype hand-held camera. The proposed algorithm was used to process the images using enhancement techniques and the glands were automatically segmented. A comparison of glands of normal eyes versus MGD-affected eyes is performed using five metrics presented in this study: (i) drop-out, (ii) length, (iii) width, (iv) the number of glands, and (v) the number of tortuous glands.
RESULTS
The 95% confidence interval for the metrics did not show any overlap between the two groups. In MGD patients, the drop-out ratio was higher than normal. The length and number of glands were significantly lesser than normal. A number of tortuous glands were more in the MGD group. The metrics for MGD versus healthy and cut-off ranges were computed in the results.
CONCLUSION
The prototype infrared hand-held meibographer and the proposed automatic algorithm for gland segmentation and quantification are effective aids in MGD diagnosis. We present a set of five metrics, which are clinically relevant for guiding clinicians in the diagnosis of MGD.
Topics: Humans; Meibomian Glands; Eyelid Diseases; Cross-Sectional Studies; Prospective Studies; Dry Eye Syndromes; Tears; Meibomian Gland Dysfunction
PubMed: 37026276
DOI: 10.4103/IJO.IJO_2930_22 -
Indian Journal of Ophthalmology Apr 2023To compare the function and morphology of the meibomian glands and the ocular surface of individuals from highland and lowland. (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
To compare the function and morphology of the meibomian glands and the ocular surface of individuals from highland and lowland.
METHODS
This was a randomized controlled trial. The study was performed with 104 individuals (51 individuals from the highland and 53 individuals from the lowland). Detailed eye examinations comprising tear meniscus height, lipid layer grading, non-invasive Keratograph tear breakup time (NIKBUT), and scoring of the meibomian glands from the upper and lower eyelids of the individuals were performed by Keratograph 5M (OCULUS, Wetzlar, Germany). Symptoms related to dry eye disease were assessed using the Ocular Surface Disease Index (OSDI).
RESULTS
In the highland group, tear meniscus height was lower (P = 0.024), lipid layer grade, as well as all the meiboscores were higher (P < 0.05) than that in the lowland group. The OSDI (P = 0.018) and the percentage of dry eye disease were also higher as compared to that of the lowland group (P = 0.032). The first NIKBUT and average NIKBUT did not differ significantly between groups. The frequency of plugged meibomian gland orifices was greater in the lowland group compared to the highland group (P = 0.036).
CONCLUSION
It was observed that dry eye disease was more common in the highland group. The morphological changes of meibomian gland dropout were significant in highlanders as demonstrated objectively with Keratograph 5M. Our study may raise a concern for environmental influences on ocular surface changes.
Topics: Humans; Meibomian Glands; Altitude; Dry Eye Syndromes; Tears; Lipids
PubMed: 37026287
DOI: 10.4103/IJO.IJO_2657_22 -
Eye (London, England) May 2019
Topics: Humans; Meibomian Gland Dysfunction; Meibomian Glands; Microscopy, Confocal; Tears
PubMed: 30728489
DOI: 10.1038/s41433-019-0351-0 -
Eye & Contact Lens Mar 2020The clinical, scientific, economic, and regulatory impact of validated biomarkers and surrogate endpoints has the potential to revolutionize the approach to ocular... (Review)
Review
The clinical, scientific, economic, and regulatory impact of validated biomarkers and surrogate endpoints has the potential to revolutionize the approach to ocular surface diseases. At present, there is a growing interest in developing biomarkers for dry eye disease, and other ocular surface disorders and imaging are of the most promising approaches to this issue. Among the several and constantly evolving imaging technologies, some tools that are aimed to assess tear film stability and volume, meibomian gland morphology and function, and ocular surface microanatomy are now supported by a good body of evidence. To date, clinical trials on ocular surface diseases have slowly started incorporating imaging biomarkers for disease diagnosis and stratification and as surrogate endpoints. Major efforts are still needed, mainly aimed to improve automatic acquisition and quantitative analysis, standardization (standard operating procedures, normative databases etc.), and validation of imaging biomarkers.
Topics: Biomarkers; Diagnostic Techniques, Ophthalmological; Dry Eye Syndromes; Humans; Meibomian Glands; Tears
PubMed: 31469757
DOI: 10.1097/ICL.0000000000000650 -
Arquivos Brasileiros de Oftalmologia 2022In this prospective study, we compared ocular clinical variables in patients with acne vulgaris with those of healthy controls. These variables included tear film...
PURPOSE
In this prospective study, we compared ocular clinical variables in patients with acne vulgaris with those of healthy controls. These variables included tear film break-up time, meibomian gland dropout rate, and anterior chamber parameters.
METHODS
Our sample comprised 73 eyes from 73 patients with acne vulgaris and 67 eyes from 67 healthy controls. All participants underwent a non-invasive first tear film break-up time test and the average tear film break-up time was evaluated. Meibography was used to identify any meibomian gland dropout. The parameters of the cornea and anterior chamber were measured using Scheimpflug topography imaging. Finally, the ocular surface disease index questionnaire was administered to score each participant on their subjective experience of ocular complaints.
RESULTS
The noninvasive first tear film break-up time values of the acne vulgaris Group and the control Group were 4.7 ± 2.8 and 6.4 ± 3.5 sec, respectively. There was a significant difference between the groups (p=0.016). The number of eyes with tear break-up at any time during the measurement period was also significantly higher in the acne Group (p=0.018). In the acne vulgaris Group, the mean meibomian gland dropout rates were 33.21 ± 15.5% in the upper lids and 45.4 ± 14.5% in the lower lids. In the control group, these rates were 15.7 ± 6.9% and 21 ± 9.7% respectively. Dropout was significantly higher in the acne group for both the upper and lower lids (p=0.000).
CONCLUSION
We found impaired tear stability in patients with acne vulgaris and a high rate of meibomian gland dropout. These glands play a key role in tear stability and their dropout is likely to result in evaporative dry eye. Measurement of the variables in this study allows objective diagnosis of this condition using a non-invasive, dye-free methodology, with minimum contact.
Topics: Humans; Meibomian Glands; Prospective Studies; Tears; Dry Eye Syndromes; Acne Vulgaris
PubMed: 36169424
DOI: 10.5935/0004-2749.2021-0038 -
Investigative Ophthalmology & Visual... Oct 2021This exploratory study aimed to investigate the morphological and pathological alterations of the meibomian gland (MG) with the Staphylococcus aureus crude extracts...
PURPOSE
This exploratory study aimed to investigate the morphological and pathological alterations of the meibomian gland (MG) with the Staphylococcus aureus crude extracts (SACEs) treatment.
METHODS
Mouse MG explants were cultured and differentiated with or without SACEs for 48 hours. Explant's viability and cell death were determined by thiazolyl blue tetrazolium bromide (MTT) assay and TUNEL assay. MG morphology was observed by Hematoxylin and Eosin staining. Lipid droplet production was detected by Nile Red staining and LipidTox immunostaining. The pro-inflammatory cytokines were detected by ELISA. The relative gene and protein expression in MG explants was determined via quantitative RT-PCR, immunostaining, and immunoblotting. The components of the SACEs were analyzed by immunoblotting and silver staining.
RESULTS
Our findings demonstrated that the SACEs treatment induced overexpression of keratin 1 (Krt1) in the ducts and acini of MG explants, accompanied by a decrease in viability and an increase in cell death in explants. Furthermore, the SACEs treatment dose-dependently increased the levels of TNF-α, IL-1β, and IL-6 in MG explants. The SACEs treatment induced activation of the nuclear factor kappa B (NF-κB) and AIM2 (absent in melanoma 2)/ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain) inflammasome signaling pathway in explants. Further investigation showed expression of the key adipogenesis-related molecule peroxisome proliferator-activated receptor γ was decreased after SACEs treatment. However, no change was found in the lipid synthesis of MG explants after treatment with the SACEs. Staphylococcal enterotoxins B (SEB) was detected in the SACEs. SEB induced the overexpression of Krt1 and IL-1β in ducts and acini of MG explants.
CONCLUSIONS
Our findings confirm that Staphylococcus aureus induced hyperkeratinization and pro-inflammatory cytokines expression in MG explants ducts and acini. These effects might be mediated by SEB. Activation of the NF-κB and AIM2/ASC signaling pathway is involved in this process.
Topics: Animals; Apoptosis; Cytokines; Disease Models, Animal; Down-Regulation; Eye Infections, Bacterial; Gene Expression Regulation; Inflammasomes; Male; Meibomian Gland Dysfunction; Meibomian Glands; Mice; Signal Transduction; Staphylococcal Infections; Staphylococcus aureus
PubMed: 34643663
DOI: 10.1167/iovs.62.13.11 -
PloS One 2019To analyze how ocular surface parameters correlate to presence of pterygium and investigate the possible impact of pterygia on tear film findings and meibomian glands...
PURPOSE
To analyze how ocular surface parameters correlate to presence of pterygium and investigate the possible impact of pterygia on tear film findings and meibomian glands findings.
METHODS
We investigated objective parameters of the ocular surface such as conjunctival hyperemia, tear film stability and volume, meibomian gland dysfunction, dry eye disease, corneal topography comparing healthy individuals and correlating with the pterygium clinical presentation.
RESULTS
A total of 83 patients were included. Corneal astigmatism induction was 2.65 ± 2.52 D (0.4-11.8). The impact of pterygium on the ocular surface parameters compared to matched controls was seen in: conjunctival hyperemia (control 1.55±0.39/pterygium 2.14±0.69; p = 0.0001), tear meniscus height (control 0.24±0.05 mm/pterygium 0.36±0.14mm; p 0.0002), meiboscore lower eyelid (control 0.29±0.64/pterygium 1.38±0.95; p 0.0001) and meiboscore upper eyelid (control 0.53±0.62/pterygium 0.98±0.75; p = 0.0083). We found a high number of pterygium patients (88%) presented meibomian gland alterations. Interestingly, meibomian gland loss was coincident to the localization of the pterygium in 54% of the upper and 77% lower lids.
CONCLUSION
Pterygium greatly impacts on ocular surface by inducing direct alterations in the pattern of meibomian glands besides corneal irregularities, conjunctival hyperemia and lacrimal film alterations, inducing significant symptoms and potential signs of dysfunction.
Topics: Adult; Aged; Anterior Eye Segment; Case-Control Studies; Corneal Topography; Female; Humans; Male; Meibomian Glands; Middle Aged; Pterygium; Severity of Illness Index
PubMed: 31513590
DOI: 10.1371/journal.pone.0213956