Cornea

Cornea Publications

Argüeso P. Human ocular mucins: The endowed guardians of sight. Adv Drug Deliv Rev 2022;180:114074.Abstract
Mucins are an ancient group of glycoproteins that provide viscoelastic, lubricating and hydration properties to fluids bathing wet surfaced epithelia. They are involved in the protection of underlying tissues by forming a barrier with selective permeability properties. The expression, processing and spatial distribution of mucins are often determined by organ-specific requirements that in the eye involve protecting against environmental insult while allowing the passage of light. The human ocular surface epithelia have evolved to produce an extremely thin and watery tear film containing a distinct soluble mucin product secreted by goblet cells outside the visual axis. The adaptation to the ocular environment is notably evidenced by the significant contribution of transmembrane mucins to the tear film, where they can occupy up to one-quarter of its total thickness. This article reviews the tissue-specific properties of human ocular mucins, methods of isolation and detection, and current approaches to model mucin systems recapitulating the human ocular surface mucosa. This knowledge forms the fundamental basis to develop applications with a promising biological and clinical impact.
Roldan AM, De Arrigunaga S, Ciolino JB. Effect of Autologous Serum Eye Drops on Corneal Haze After Corneal Crosslinking. Optom Vis Sci 2021;Abstract
SIGNIFICANCE: Corneal haze remains a frequent postoperative finding in patients undergoing corneal crosslinking. It has been shown that autologous serum tears promote epithelial healing and reduce postoperative pain; however, the role in the prevention of corneal haze has not been reported. PURPOSE: To compare the effect of autologous serum tears vs. preservative-free artificial tears on the prevention and resolution of post-crosslinking corneal haze. METHODS: A retrospective cohort study was conducted in a sample population from one surgeon at a tertiary eye center from 2016 to 2019. Seventy-six eyes of consecutive patients who underwent crosslinking were included. Records were reviewed for corneal Scheimpflug densitometry values and maximum keratometry (Kmax), epithelial healing time, and the use of either autologous serum tears or preservative-free artificial tears. Corneal densitometry values, expressed in standardized Grayscale Units (GSU), were recorded for the anterior 150 μm corneal stroma and in the 0.0-2.0 mm and 2.0-6.0 mm zones. RESULTS: 44 eyes received autologous serum tears, while 32 eyes received preservative-free artificial tears. The baseline GSU of the anterior stromal 0-2 mm annulus and the 2-6 mm annulus did not significantly differ between groups (P = .5 and P = .4, respectively). There was a statistically significant increase in mean GSU for both anterior 0-2 mm and 2-6 mm zones between baseline and 1 month (P < .001) and 3 months (P < .001). When comparing the two groups, no statistically significant difference was found postoperatively between the mean GSU at one month for the anterior 0-2 mm (P = .38) nor the 2-6 mm zone (P = .12); or for the third month (P = .60 and P = .44, respectively). CONCLUSIONS: Using Scheimpflug densitometry, we did not find a significant difference in the post-crosslinking corneal haze at 1 and 3 postoperative months between patients that use autologous serum tears or preservative-free artificial tears.
Inomata T, Nakamura M, Sung J, Midorikawa-Inomata A, Iwagami M, Fujio K, Akasaki Y, Okumura Y, Fujimoto K, Eguchi A, Miura M, Nagino K, Shokirova H, Zhu J, Kuwahara M, Hirosawa K, Dana R, Murakami A. Smartphone-based digital phenotyping for dry eye toward P4 medicine: a crowdsourced cross-sectional study. NPJ Digit Med 2021;4(1):171.Abstract
Multidimensional integrative data analysis of digital phenotyping is crucial for elucidating the pathologies of multifactorial and heterogeneous diseases, such as the dry eye (DE). This crowdsourced cross-sectional study explored a novel smartphone-based digital phenotyping strategy to stratify and visualize the heterogenous DE symptoms into distinct subgroups. Multidimensional integrative data were collected from 3,593 participants between November 2016 and September 2019. Dimension reduction via Uniform Manifold Approximation and Projection stratified the collected data into seven clusters of symptomatic DE. Symptom profiles and risk factors in each cluster were identified by hierarchical heatmaps and multivariate logistic regressions. Stratified DE subgroups were visualized by chord diagrams, co-occurrence networks, and Circos plot analyses to improve interpretability. Maximum blink interval was reduced in clusters 1, 2, and 5 compared to non-symptomatic DE. Clusters 1 and 5 had severe DE symptoms. A data-driven multidimensional analysis with digital phenotyping may establish predictive, preventive, personalized, and participatory medicine.
Chang W-C, Abe R, Anderson P, Anderson W, Ardern-Jones MR, Beachkofsky TM, Bellón T, Biala AK, Bouchard C, Cavalleri GL, Chapman N, Chodosh J, Choi HK, Cibotti RR, Divito SJ, Dewar K, Dehaeck U, Etminan M, Forbes D, Fuchs E, Goldman JL, Holmes JH, Hope EA, Hung S-I, Hsieh C-L, Iovieno A, Jagdeo J, Kim MK, Koelle DM, Lacouture ME, Le Pallec S, Lehloenya RJ, Lim R, Lowe A, McCawley J, McCawley J, Micheletti RG, Mockenhaupt M, Niemeyer K, Norcross MA, Oboh D, Olteanu C, Pasieka HB, Peter J, Pirmohamed M, Rieder M, Saeed HN, Shear NH, Shieh C, Straus S, Sukasem C, Sung C, Trubiano JA, Tsou S-Y, Ueta M, Volpi S, Wan C, Wang H, Wang Z-Q, Weintraub J, Whale C, Wheatley LM, Whyte-Croasdaile S, Williams KB, Wright G, Yeung SN, Zhou L, Chung W-H, Phillips EJ, Carleton BC. Corrigendum to 'SJS/TEN 2019: From science to translation' [J. Dermatol. Sci. 98/1 (2020) 2-12]. J Dermatol Sci 2021;104(2):146-147.
Gárriz A, Aubry S, Wattiaux Q, Bair J, Mariano M, Hatzipetrou G, Bowman M, Morokuma J, Ortiz G, Hamrah P, Dartt DA, Zoukhri D. Role of the Phospholipase C Pathway and Calcium Mobilization in Oxytocin-Induced Contraction of Lacrimal Gland Myoepithelial Cells. Invest Ophthalmol Vis Sci 2021;62(14):25.Abstract
Purpose: We reported that oxytocin (OXT), added to freshly prepared lacrimal gland lobules, induced myoepithelial cell (MEC) contraction. In other systems, OXT activates phospholipase C (PLC) generating Inositol 1,4,5-trisphosphate (IP3) which increases intracellular calcium concentration ([Ca2+]i) causing contraction. The aim of the current study was to investigate the role of this pathway in OXT-induced contraction of MEC. Methods: Tear volume was measured using the cotton thread method. Lacrimal gland MEC were isolated and propagated from α-smooth muscle actin (SMA)-green fluorescent protein (GFP) mice, in which MEC express GFP making them easily identifiable. RNA and protein samples were prepared for RT-PCR and Western blotting for G protein expression. Changes in [Ca2+]i were measured in Fura-2 loaded MEC using a ratio imaging system. MEC contraction was monitored in real time and changes in cell size were quantified using ImageJ software. Results: OXT applied either topically to surgically exposed lacrimal glands or delivered subcutaneously resulted in increased tear volume. OXT stimulated lacrimal gland MEC contraction in a dose-dependent manner, with a maximum response at 10-7 M. MEC express the PLC coupling G proteins, Gαq and Gα11, and their activation by OXT resulted in a concentration-dependent increase in [Ca2+]i with a maximum response at 10-6 M. Furthermore, the activation of the IP3 receptor to increase [Ca2+]i is crucial for OXT-induced MEC contraction since blocking the IP3 receptor with 2-APB completely abrogated this response. Conclusions: We conclude that OXT uses the PLC/Ca2+ pathway to stimulate MEC contraction and increase lacrimal gland secretion.
Olafsson J, Lai X, Landsend ECS, Olafsson S, Parissi E, Utheim ØA, Raeder S, Badian RA, Lagali N, Dartt DA, Utheim TP. TheraPearl Eye Mask and Blephasteam for the treatment of meibomian gland dysfunction: a randomized, comparative clinical trial. Sci Rep 2021;11(1):22386.Abstract
Meibomian gland dysfunction (MGD) is the most common cause of dry eye disease (DED). In this study, we aimed to compare the effects of eyelid warming treatment using either TheraPearl Eye Mask (Bausch & Lomb Inc., New York, USA) or Blephasteam (Spectrum Thea Pharmaceuticals LTD, Macclesfield, UK) in a Norwegian population with mild to moderate MGD-related DED. An open label, randomized comparative trial with seventy patients (49 females, 21 males; mean age 53.6 years). Patients were randomly assigned to treatment with Blephasteam (n = 37) or TheraPearl (n = 33). All received a hyaluronic acid based artificial tear substitute (Hylo-Comod, Ursapharm, Saarbrücken, Germany). Patients were examined at baseline, and at three and six months initiation of treatment. Treatment efficacy was primarily evaluated by fluorescein breakup time (FBUT) and Ocular Surface Disease Index (OSDI) scores. Other outcome measures included ocular surface staining (OSS), Schirmer's test, and meibomian quality and expressibility. Baseline parameter values did not differ between the groups. After six months of treatment, Blephasteam improved FBUT by 3.9 s (p < 0.01) and OSDI by 13.7 (p < 0.01), TheraPearl improved FBUT by 2.6 s (p < 0.01) and OSDI by 12.6 (p < 0.01). No difference between treatments was detected at 6 months (p = 0.11 for FBUT and p = 0.71 for OSDI), nor were there differences in the other tested parameters between the treatment groups. Blephasteam and TheraPearl are equally effective in treating mild to moderate MGD in a Norwegian population after 6-months of treatment.Clinicaltrials.gov ID: NCT03318874; Protocol ID: 2014/1983; First registration: 24/10/2017.
Lužnik Marzidovšek Z, Blanco T, Sun Z, Alemi H, Ortiz G, Nakagawa H, Chauhan SK, Taylor AW, Jurkunas UV, Yin J, Dana R. The neuropeptide alpha-melanocyte-stimulating hormone is critical for corneal endothelial cell protection and graft survival after transplantation. Am J Pathol 2021;Abstract
Corneal transplantation is the most common form of tissue transplantation. The success of corneal transplantation mainly relies on the integrity of corneal endothelial cells (CEnCs), which maintain tissue transparency by pumping out excess water from the cornea. After transplantation, the rate of CEnC loss far exceeds that seen with normal aging, and this can threaten sight. The underlying mechanisms are poorly understood. Alpha-melanocyte-stimulating hormone (α-MSH) is a neuropeptide that is constitutively found in the aqueous humor with both cytoprotective and immunomodulatory effects. We found high expression of melanocortin 1 receptor (MC1R), the receptor for α-MSH, on CEnCs. We then set to determine the effect of α-MSH/MC1R signaling on endothelial function and allograft survival in vitro and in vivo using MC1R signaling-deficient mice (Mc1re/e mice with a nonfunctional MC1R). Herein, we show that in addition to its well-known immunomodulatory effect, α-MSH has cytoprotective effects on CEnCs after corneal transplantation and the loss of MC1R signaling significantly decreases long-term graft survival in vivo. In conclusion, α-MSH/MC1R signaling is critical for CEnC function and graft survival after corneal transplantation.
Yeung V, Sriram S, Tran JA, Guo X, Hutcheon AEK, Zieske JD, Karamichos D, Ciolino JB. FAK Inhibition Attenuates Corneal Fibroblast Differentiation In Vitro. Biomolecules 2021;11(11)Abstract
Corneal fibrosis (or scarring) occurs in response to ocular trauma or infection, and by reducing corneal transparency, it can lead to visual impairment and blindness. Studies highlight important roles for transforming growth factor (TGF)-β1 and -β3 as modulators in corneal wound healing and fibrosis, leading to increased extracellular matrix (ECM) components and expression of α-smooth muscle actin (αSMA), a myofibroblast marker. In this study, human corneal fibroblasts (hCF) were cultured as a monolayer culture (2D) or on poly-transwell membranes to generate corneal stromal constructs (3D) that were treated with TGF-β1, TGF-β3, or TGF-β1 + FAK inhibitor (FAKi). Results show that hCF 3D constructs treated with TGF-β1 or TGF-β3 impart distinct effects on genes involved in wound healing and fibrosis-ITGAV, ITGB1, SRC and ACTA2. Notably, in the 3D construct model, TGF-β1 enhanced αSMA and focal adhesion kinase (FAK) protein expression, whereas TGF-β3 did not. In addition, in both the hCF 2D cell and 3D construct models, we found that TGF-β1 + FAKi attenuated TGF-β1-mediated myofibroblast differentiation, as shown by abrogated αSMA expression. This study concludes that FAK signaling is important for the onset of TGF-β1-mediated myofibroblast differentiation, and FAK inhibition may provide a novel beneficial therapeutic avenue to reduce corneal scarring.
Greiner JV, Glonek T. Intracellular ATP Concentration and Implication for Cellular Evolution. Biology (Basel) 2021;10(11)Abstract
Crystalline lens and striated muscle exist at opposite ends of the metabolic spectrum. Lens is a metabolically quiescent tissue, whereas striated muscle is a mechanically dynamic tissue with high-energy requirements, yet both tissues contain millimolar levels of ATP (>2.3 mM), far exceeding their underlying metabolic needs. We explored intracellular concentrations of ATP across multiple cells, tissues, species, and domains to provide context for interpreting lens/striated muscle data. Our database revealed that high intracellular ATP concentrations are ubiquitous across diverse life forms including species existing from the Precambrian Era, suggesting an ancient highly conserved role for ATP, independent of its widely accepted view as primarily "metabolic currency". Our findings reinforce suggestions that the primordial function of ATP was non-metabolic in nature, serving instead to prevent protein aggregation.
Roldan AM, Zebardast N, Pistilli M, Khachatryan N, Payal A, Begum H, Artornsombudh P, Pujari SS, Rosenbaum JT, Sen NH, Suhler EB, Thorne JE, Bhatt NP, Foster SC, Jabs DA, Levy-Clarke GA, Nussenblatt RB, Buchanich JM, Kempen JH, for Group SITED (SITE) CSR. Corneal Endothelial Transplantation in Uveitis: Incidence and Risk Factors. Am J Ophthalmol 2021;Abstract
PURPOSE: To estimate the incidence of corneal endothelial transplantation and identify risk factors among patients with non-infectious ocular inflammation. DESIGN: Retrospective cohort study. METHODS: Adult patients attending United States tertiary uveitis care facilities diagnosed with non-infectious ocular inflammation were identified from the Systemic Immunosuppressive Therapy for Eye Diseases Cohort Study. Time-to-event analysis was used to estimate the incidence of corneal endothelial transplantation (CET), including penetrating keratoplasty, Descemet stripping endothelial keratoplasty, or Descemet Membrane Endothelial Keratoplasty procedures. The incidence of CET was calculated; potential risk factors for CET were also evaluated using Cox regression, accounting for correlation between eyes of the same patient. RESULTS: Overall, 14,264 eyes met eligibility criteria for this analysis with a median follow-up 1.8 eye-years. The Kaplan-Meier estimated incidence of CET within 10 years was 1.10% (95% CI, 0.68%-1.53%). Risk factors for CET included age >60 years vs. <40 years (aHR 16.5; 95% CI,4.70-57.9), anterior uveitis and scleritis vs. other types (aHR 2.97; 95% CI, 1.46-6.05 and aHR 4.14; 95% CI,1.28-13.4, respectively), topical corticosteroid treatment (aHR 2.84; 95% CI, 1.32-6.13), cataract surgery (aHR 4.44; 95% CI, 1.73-11.4), tube shunt surgery (aHR 11.9; 95% CI, 5.30-26.8), band keratopathy (aHR 5.12; 95% CI, 2.34-11.2), and hypotony (aHR 7.38; 95% CI, 3.14-17.4). Duration of uveitis, trabeculectomy, PAS, and ocular hypertension had no significant association after multivariate adjustment. CONCLUSIONS: In patients with ocular inflammation, CET occurred infrequently. Tube shunt surgery, hypotony, band keratopathy, cataract surgery, and anterior segment inflammation were associated with increased risk of undergoing corneal endothelial transplantation; these factors likely are associated with endothelial cell damage.
Kenyon KR. Comment on Cornea Classic Article: Kim JC and Tseng SCG: Transplantation of Preserved Amniotic Membrane for Surface Reconstruction in Severely Damaged Rabbit Corneas (Cornea 14: 473-484; 1995).". Cornea 2021;Abstract
ABSTRACT: Following identification of limbal stem cells, efforts have been devoted to restore and/or replace these essential progenitors of the corneal epithelium. Limbal stem cell deficiency, commonly a consequence of ocular chemical injury, results in clinically compromised vision consequent to corneal conjunctivalization. The insight of Kim and Tseng provided experimental proof of the concept that even in the presence of total limbal stem cell deficiency, amnion membrane overlay grafts can promote limbal recovery as a means of ocular surface reconstruction.
Woodward AM, Feeley MN, Rinaldi J, Argüeso P. CRISPR/Cas9 genome editing reveals an essential role for basigin in maintaining a nonkeratinized squamous epithelium in cornea. FASEB Bioadv 2021;3(11):897-908.Abstract
One of the primary functions of nonkeratinized stratified squamous epithelia is to protect underlying tissues against chemical, microbial, and mechanical insult. Basigin is a transmembrane matrix metalloproteinase inducer commonly overexpressed during epithelial wound repair and cancer but whose physiological significance in normal epithelial tissue has not been fully explored. Here we used a CRISPR/Cas9 system to study the effect of basigin loss in a human cornea model of squamous epithelial differentiation. We find that epithelial cell cultures lacking basigin change shape and fail to produce a flattened squamous layer on the apical surface. This process is associated with the abnormal expression of the transcription factor SPDEF and the decreased biosynthesis of MUC16 and involucrin necessary for maintaining apical barrier function and structural integrity, respectively. Expression analysis of genes encoding tight junction proteins identified a role for basigin in promoting physiological expression of occludin and members of the claudin family. Functionally, disruption of basigin expression led to increased epithelial cell permeability as evidenced by the decrease in transepithelial electrical resistance and increase in rose bengal flux. Overall, these results suggest that basigin plays a distinct role in maintaining the normal differentiation of stratified squamous human corneal epithelium and could have potential implications to therapies targeting basigin function.
Sharifi S, Islam MM, Sharifi H, Islam R, Koza D, Reyes-Ortega F, Alba-Molina D, Nilsson PH, Dohlman CH, Mollnes TE, Chodosh J, Gonzalez-Andrades M. Tuning gelatin-based hydrogel towards bioadhesive ocular tissue engineering applications. Bioact Mater 2021;6(11):3947-3961.Abstract
Gelatin based adhesives have been used in the last decades in different biomedical applications due to the excellent biocompatibility, easy processability, transparency, non-toxicity, and reasonable mechanical properties to mimic the extracellular matrix (ECM). Gelatin adhesives can be easily tuned to gain different viscoelastic and mechanical properties that facilitate its ocular application. We herein grafted glycidyl methacrylate on the gelatin backbone with a simple chemical modification of the precursor, utilizing epoxide ring-opening reactions and visible light-crosslinking. This chemical modification allows the obtaining of an elastic protein-based hydrogel (GELGYM) with excellent biomimetic properties, approaching those of the native tissue. GELGYM can be modulated to be stretched up to 4 times its initial length and withstand high tensile stresses up to 1.95 MPa with compressive strains as high as 80% compared to Gelatin-methacryloyl (GeIMA), the most studied derivative of gelatin used as a bioadhesive. GELGYM is also highly biocompatible and supports cellular adhesion, proliferation, and migration in both 2 and 3-dimensional cell-cultures. These characteristics along with its super adhesion to biological tissues such as cornea, aorta, heart, muscle, kidney, liver, and spleen suggest widespread applications of this hydrogel in many biomedical areas such as transplantation, tissue adhesive, wound dressing, bioprinting, and drug and cell delivery.

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