The cellular basis of corneal transparency: Evidence for ‘corneal crystallins’

Jester, James V.; Møller‐Pedersen, Torben; Huang, Jingjing; Sax, Christina M.; Kays, W. T.; Cavangh, H. D.; Petroll, Walter M; Piatigorsky, Joram

doi:10.1242/jcs.112.5.613

Cited by 416 publications

(44 citation statements)

References 46 publications

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“…This explains the low density of keratocytes in the nocturnal R. egyptiacus. The present findings came in accordance and parallel other land mammals ( Jester et al, 1999;Møller-Pedersen, 2004).…”

Section: Advances In Animal Andsupporting

confidence: 93%

Microstructure Adaptation in Mammalian Corne a Comparative Study

Abdelftah¹,

Ragab²,

Abo‐Eleneen³

et al. 2021

AAVS

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Due to the epithelial ion barrier, the stromal latticelike structure of collagen fibrils, and the endothelial cells, the corneas of most vertebrate's species stay transparent. The corneal epithelium, the corneal endothelium, or both, play an important role in controlling corneal hydration, depending on the species. Three mammalian families [Pteropodidae (Rousttus egyptiacus), Leporidae (Oryctolagus caniculus; Muridae (Rattus norvigerious)] of the present study were collected from different locations of Egypt. The investigated cornea was dissected free from the orbit and prepared for light and scanning electron microscopy and special stain. Three investigated mammalian species composed of three identical layers; epithelium, stroma, and endothelium besides appearance of Bowmen's membrane in Rousttus egyptiacus and Oryctolagus caniculus. On the other hand, descemet's membrane appear only in Oryctolagus caniculus. The investigated epithelial layers showed moderate affinity to stain with by Periodic Acid Schiff stain in Roussttus egyptiacus and Oryctolagus caniculus, although high activity with PAS stain in Rattus nirvigurios. Their corneal epithelium cells distinguished by irregular polygonal cells covered with moderated density of shorted microplicae. The ultimate goal is to keep the cornea transparent and provide the greatest refract. According to the rabbit cornea and its adaptive trends have eloquently described the vertebrate eye's relative optical features. The study presents a brief image/account of certain structures of cornea for three of mammalian's species and to correlate them with the different circumstances and variation of habitats.

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Section: Advances In Animal Andsupporting

confidence: 93%

Microstructure Adaptation in Mammalian Corne a Comparative Study

Abdelftah¹,

Ragab²,

Abo‐Eleneen³

et al. 2021

AAVS

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“…We hypothesize that the dense central area represents denatured and disorganized collagen fibrils produced by the original NaOH injury, along with myofibroblasts that developed and the large amounts of disordered extracellular matrix these fibrotic cells produced. 5 , 20 , 31 The less dense ring may be associated with less severely damaged stromal collagen and corneal fibroblasts, along with lesser amounts of disordered extracellular matrix produced by corneal fibroblasts, although further investigation would be needed to confirm this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

Topical Losartan and Corticosteroid Additively Inhibit Corneal Stromal Myofibroblast Generation and Scarring Fibrosis After Alkali Burn Injury

Sampaio

Hilgert

Shiju

et al. 2022

Trans. Vis. Sci. Tech.

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Purpose To evaluate the efficacy of losartan and prednisolone acetate in inhibiting corneal scarring fibrosis after alkali burn injury in rabbits. Methods Sixteen New Zealand White rabbits were included. Alkali injuries were produced using 1N sodium hydroxide on a 5-mm diameter Whatman #1 filter paper for 1 minute. Four corneas in each group were treated six times per day for 1 month with 50 µL of (1) 0.8 mg/mL losartan in balanced salt solution (BSS), (2) 1% prednisolone acetate, (3) combined 0.8 mg/mL losartan and 1% prednisolone acetate, or (4) BSS. Area of opacity and total opacity were analyzed in standardized slit-lamp photos with ImageJ. Corneas in both groups were cryofixed in Optimal cutting temperature (OCT) compound at 1 month after surgery, and immunohistochemistry was performed for alpha-smooth muscle actin (α-SMA) and keratocan or transforming growth factor β1 and collagen type IV with ImageJ quantitation. Results Combined topical losartan and prednisolone acetate significantly decreased slit-lamp opacity area and intensity, as well as decreased stromal myofibroblast α-SMA area and intensity of staining per section and confined myofibroblasts to only the posterior stroma with repopulation of the anterior and mid-stroma with keratocan-positive keratocytes after 1 month of treatment. Corneal fibroblasts produced collagen type IV not associated with basement membranes, and this production was decreased by topical losartan. Conclusions Combined topical losartan and prednisolone acetate decreased myofibroblast-associated fibrosis after corneal alkali burns that produced full-thickness injury, including corneal endothelial damage. Increased dosages and duration of treatment may further decrease scarring fibrosis. Translational Relevance Topical losartan and prednisolone acetate decrease myofibroblast-mediated scarring fibrosis after corneal injury.

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“…Other biomarkers of myofibroblast formation include upregulation of vimentin and desmin, which reduces tissue transparency. These changes in growth factor expression patterns are in marked contrast to the physiological milieu sustaining quiescent keratocyte behavior ( 71 , 72 ).…”

Section: Healing Process Of Corneal Woundsmentioning

confidence: 88%

Roles of Epithelial and Mesenchymal TRP Channels in Mediating Inflammatory Fibrosis

et al. 2022

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The maintenance of normal vision is dependent on preserving corneal transparency. For this to occur, this tissue must remain avascular and its stromal architecture needs to be retained. Epithelial transparency is maintained provided the uppermost stratified layers of this tissue are composed of terminally differentiated non-keratinizing cells. In addition, it is essential that the underlying stromal connective tissue remains avascular and scar-free. Keratocytes are the source of fibroblasts that are interspersed within the collagenous framework and the extracellular matrix. In addition, there are sensory nerve fibers whose lineage is possibly either neural crest or mesenchymal. Corneal wound healing studies have been undertaken to delineate the underlying pathogenic responses that result in the development of opacification following chemical injury. An alkali burn is one type of injury that can result in severe and long- lasting losses in ocular transparency. During the subsequent wound healing process, numerous different proinflammatory cytokines and proteolytic enzymes undergo upregulation. Such increases in their expression levels induce maladaptive expression of sustained stromal inflammatory fibrosis, neovascularization, and losses in the smooth optical properties of the corneal outer surface. It is becoming apparent that different transient receptor potential channel (TRP) isoforms are important players in mediating these different events underlying the wound healing process since injury upregulates both their expression levels and functional involvement. In this review, we focus on the involvement of TRPV1, TRPA1 and TRPV4 in mediating some of the responses that underlie the control of anterior ocular tissue homeostasis under normal and pathological conditions. They are expressed on both different cell types throughout this tissue and also on corneal sensory nerve endings. Their roles have been extensively studied as sensors and transducers of environmental stimuli resulting from exposure to intrinsic modulators and extrinsic ligands. These triggers include alteration of the ambient temperature and mechanical stress, etc., that can induce pathophysiological responses underlying losses in tissue transparency activated by wound healing in mice losses in tissue transparency. In this article, experimental findings are reviewed about the role of injury-induced TRP channel activation in mediating inflammatory fibrotic responses during wound healing in mice.

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The cellular basis of corneal transparency: Evidence for ‘corneal crystallins’

Cited by 416 publications

References 46 publications

Microstructure Adaptation in Mammalian Corne a Comparative Study

Microstructure Adaptation in Mammalian Corne a Comparative Study

Topical Losartan and Corticosteroid Additively Inhibit Corneal Stromal Myofibroblast Generation and Scarring Fibrosis After Alkali Burn Injury

Roles of Epithelial and Mesenchymal TRP Channels in Mediating Inflammatory Fibrosis

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