Vortex or whorl formation of cultured human corneal epithelial cells induced by magnetic fields

The inferocentral whorl region and its directional patterns in the corneal sub-basal nerve plexus: A review

There has been a growing application of in vivo confocal microscopy (IVCM) in the examination of corneal microstructure, including different corneal layers and corneal nerve fibers in health and in pathological conditions. Corneal nerves forming the sub-basal nerve plexus (SBNP) beneath the corneal basal epithelial cell layer in particular have been intensively researched in health and disease as a marker for corneal neurophysioanatomical and degenerative changes. One intriguing feature in the SBNP that is found inferior to the corneal apex, is a whorl-like pattern (or vortex) of nerves, which represents an anatomical landmark. Evidence has indicated that the architecture of this 'whorl region' is dynamic, changing with time in healthy individuals but also in disease conditions such as in diabetic neuropathy and keratoconus. This review summarizes the known information regarding the characteristics and significance of the whorl region of nerves in the corneal SBNP, as a potential area of high relevance for future disease monitoring and diagnostics.

Vortex Keratopathy as a Presenting Feature of Ocular Mucous Membrane Pemphigoid

PURPOSE

The aim of this study was to describe the presenting feature of vortex keratopathy in 3 patients with biopsy-proven ocular mucous membrane pemphigoid (OMMP).

METHODS

The first patient was a 52-year-old woman with chronic redness and foreign body sensation for 3 years who presented with unilateral vortex keratopathy. Seven months later, in the same eye, she developed conjunctival signs suggestive of OMMP. The second patient was a 33-year-old woman with similar chronic symptoms that were exacerbated by pterygium surgery. Clinical examination revealed vortex keratopathy in the right eye with subtle conjunctival signs suggestive of OMMP. The third patient was a 70-year-old woman with complaints of repeated episodes of redness and foreign body sensation for 18 months who presented with vortex keratopathy in the right eye and conjunctival signs suggestive of OMMP in the same eye. To confirm the clinical diagnosis, bilateral conjunctival biopsy was performed in all patients.

RESULTS

OMMP was diagnosed based on conjunctival signs and confirmed on direct immunofluorescence positivity, demonstrating antibodies characteristic and diagnostic of OMMP in the basement membrane zone. A unique feature that preceded or coexisted with the conjunctival signs was unilateral vortex keratopathy seen in all 3 patients, independent of the stage of the disease at which they presented.

CONCLUSIONS

Vortex keratopathy can be a presenting feature in patients with OMMP. A complete ocular surface examination, especially checking the medial canthus for keratin and the inferior fornix for foreshortening, is necessary. Conjunctival biopsy should be performed in all cases to confirm the clinical diagnosis wherever required.

Integer topological defects organize stresses driving tissue morphogenesis

Tissues acquire function and shape via differentiation and morphogenesis. Both processes are driven by coordinating cellular forces and shapes at the tissue scale, but general principles governing this interplay remain to be discovered. Here we report that self-organization of myoblasts around integer topological defects, namely spirals and asters, suffices to establish complex multicellular architectures. In particular, these arrangements can trigger localized cell differentiation or, alternatively, when differentiation is inhibited, they can drive the growth of swirling protrusions. Both localized differentiation and growth of cellular vortices require specific stress patterns. By analysing the experimental velocity and orientational fields through active gel theory, we show that integer topological defects can generate force gradients that concentrate compressive stresses. We reveal these gradients by assessing spatial changes in nuclear volume and deformations of elastic pillars. We propose integer topological defects as mechanical organizing centres controlling differentiation and morphogenesis.

Quantifying Material Properties of Cell Monolayers by Analyzing Integer Topological Defects

In developing organisms, internal cellular processes generate mechanical stresses at the tissue scale. The resulting deformations depend on the material properties of the tissue, which can exhibit long-ranged orientational order and topological defects. It remains a challenge to determine these properties on the time scales relevant for developmental processes. Here, we build on the physics of liquid crystals to determine material parameters of cell monolayers. Specifically, we use a hydrodynamic description to characterize the stationary states of compressible active polar fluids around defects. We illustrate our approach by analyzing monolayers of C2C12 cells in small circular confinements, where they form a single topological defect with integer charge. We find that such monolayers exert compressive stresses at the defect centers, where localized cell differentiation and formation of three-dimensional shapes is observed.

Integer topological defects of cell monolayers: Mechanics and flows

Monolayers of anisotropic cells exhibit long-ranged orientational order and topological defects. During the development of organisms, orientational order often influences morphogenetic events. However, the linkage between the mechanics of cell monolayers and topological defects remains largely unexplored. This holds specifically at the timescales relevant for tissue morphogenesis. Here, we build on the physics of liquid crystals to determine material parameters of cell monolayers. In particular, we use a hydrodynamical description of an active polar fluid to study the steady-state mechanical patterns at integer topological defects. Our description includes three distinct sources of activity: traction forces accounting for cell-substrate interactions as well as anisotropic and isotropic active nematic stresses accounting for cell-cell interactions. We apply our approach to C2C12 cell monolayers in small circular confinements, which form isolated aster or spiral topological defects. By analyzing the velocity and orientational order fields in spirals as well as the forces and cell number density fields in asters, we determine mechanical parameters of C2C12 cell monolayers. Our work shows how topological defects can be used to fully characterize the mechanical properties of biological active matter.

Comparative Anatomy of the Mammalian Corneal Subbasal Nerve Plexus

Purpose

The subbasal nerve plexus (SNP) is the densest and most recognizable component of the mammalian corneal innervation; however, the anatomical configuration of the SNP in most animal models remains incompletely described. The purpose of the current study is to describe in detail the SNP architecture in eight different mammals, including several popular animal models used in cornea research.

Methods

Corneal nerves in mouse, rat, guinea pig, rabbit, dog, macaque, domestic pig, and cow eyes were stained immunohistochemically with antiserum directed against neurotubulin. SNP architecture was documented by digital photomicrography and large-scale reconstructions, that is, corneal nerve maps, using a drawing tube attached to a light microscope.

Results

Subbasal nerve fibers (SNFs) in mice, rats, guinea pigs, dogs, and macaques radiated centrally from the corneoscleral limbus toward the corneal apex in a whorl-like or spiraling pattern. SNFs in rabbit and bovine corneas swept horizontally across the ocular surface in a temporal-to-nasal direction and converged on the inferonasal limbus without forming a spiral. SNFs in the pig cornea radiated centrifugally in all directions, like a starburst, from a focal point located equidistant between the corneal apex and the superior pole.

Conclusions

The results of the present study have demonstrated for the first time substantial interspecies differences in the architectural organization of the mammalian SNP. The physiological significance of these different patterns and the mechanisms that regulate SNP pattern formation in the mammalian cornea remain incompletely understood and warrant additional investigation.

Recovery From Amiodarone-Induced Cornea Verticillata by Application of Topical Heparin

PURPOSE

To report a case of amiodarone-induced vortex keratopathy-associated anatomical findings and subjective visual perception before and after treatment with topical heparin eye drops.

METHODS

Case report.

RESULTS

A 76-year-old man complained of halos in his vision in both his eyes due to prominent bilateral cornea verticillata. For treatment of cornea verticillata, we prescribed unpreserved eye drops of a sterile, phosphate-free solution of 0.1% sodium hyaluronate with 1300 IU/mL heparin sodium 3 times daily to the left eye, whereas the other side served as the control. The area of corneal deposits was measured by 2 examiners before and at the 1- and 3-month examination. At last follow-up, cornea verticillata had been reduced from 6 to 2 mm in area by approximately 66% from grade-III to grade-II amiodarone keratopathy.

CONCLUSIONS

In patients using amiodarone, clearing of cornea verticillata may be achieved by topical use of unpreserved eye drops of a sterile, phosphate-free solution of 0.1% sodium hyaluronate with 1300 IU/mL heparin sodium.

Neuroanatomy and Neurochemistry of Mouse Cornea

Purpose

To investigate the entire nerve architecture and content of the two main sensory neuropeptides in mouse cornea to determine if it is a good model with similarities to human corneal innervation.

Methods

Mice aged 1 to 24 weeks were used. The corneas were stained with neuronal-class βIII-tubulin, calcitonin gene–related peptide (CGRP), and substance P (SP) antibodies; whole-mount images were acquired to build an entire view of corneal innervation. To test the origin of CGRP and SP, trigeminal ganglia (TG) were processed for immunofluorescence. Relative corneal nerve fiber densities or neuron numbers were assessed by computer-assisted analysis.

Results

Between 1 and 3 weeks after birth, mouse cornea was mainly composed of a stromal nerve network. At 4 weeks, a whorl-like structure (or vortex) appeared that gradually became more defined. By 8 weeks, anatomy of corneal nerves had reached maturity. Epithelial bundles converged into the central area to form the vortex. The number and pattern of whorl-like structures were different. Subbasal nerve density and nerve terminals were greater in the center than the periphery. Nerve fibers and terminals that were CGRP-positive were more abundant than SP-positive nerves and terminals. In trigeminal ganglia, the number of CGRP-positive neurons significantly outnumbered those positive for SP.

Conclusions

This is the first study to show a complete map of the entire corneal nerves and CGRP and SP sensory neuropeptide distribution in the mouse cornea. This finding shows mouse corneal innervation has many similarities to human cornea and makes the mouse an appropriate model to study pathologies involving corneal nerves.

Promoting convergence: the Phi spiral in abduction of mouse corneal behaviors

Why do mouse corneal epithelial cells display spiraling patterns? We want to provide an explanation for this phenomenon by applying an idealized problem solving process. Specifically, we applied complementary line-fitting methods to measure transgenic epithelial reporter expression arrangements displayed on three mature, live enucleated globes to clarify the problem. Two prominent logarithmic curves were discovered, one of which displayed the ϕ ratio, an indicator of the optimal configuration in phyllotactic systems. We then utilized two different computational approaches to expose our current understanding of the behavior. In one procedure, which involved an isotropic mechanics-based finite element method, we successfully produced logarithmic spiral curves of maximum shear strain based pathlines but computed dimensions displayed pitch angles of 35° (ϕ spiral is ~17°), which was altered when we fitted the model with published measurements of coarse collagen orientations. We then used model-based reasoning in context of Peircean abduction to select a working hypothesis. Our work serves as a concise example of applying a scientific habit of mind and illustrates nuances of executing a common method to doing integrative science.

Ocular toxicity from systemically administered xenobiotics

INTRODUCTION

The eye is considered as the most privileged organ because of the blood-ocular barrier that acts as a barrier to systemically administered xenobiotics. However, there has been a significant increase in the number of reports on systemic drug-induced ocular complications. If such complications are left untreated, then it may cause permanent damage to vision. Hence, knowledge of most recent updates on ever-increasing reports of such toxicities has become imperative to develop better therapy while minimizing toxicities.

AREAS COVERED

The article is mainly divided into anterior and posterior segment manifestations caused by systemically administered drugs. The anterior segment is further elaborated on corneal complications where as the posterior segment is focused on optic nerve, retinal and vitreous complications. Furthermore, this article includes recent updates on acute and chronic ocular predicaments, in addition to discussing various associated symptoms caused by drugs.

EXPERT OPINION

Direct correlation of ocular toxicities due to systemic drug therapy is evident from current literature. Therefore, it is necessary to have detailed documentation of these complications to improve understanding and predict toxicities. We made an attempt to ensure that the reader is aware of the characteristic ocular complications, the potential for irreversible drug toxicity and indications for cessation.

Anatomy of the human corneal innervation

The anatomy of the human corneal innervation has been the subject of much investigation; however, a comprehensive description remains elusive. The purpose of the present study was to provide a detailed description of the human corneal innervation using a novel approach involving immunohistochemically stained anterior-cornea whole mounts. Sixteen donor corneas aged 19-78 years were cut with a 6.0 mm trephine into a central plug and two peripheral rims. Each specimen was sectioned serially on a cryostat to produce several 100 microm-thick stromal sections and a 100-140 microm-thick anterior-cornea whole mount that contained the entire corneal epithelium and much of the anterior stroma. The corneal innervation was stained with a primary antibody against beta neurotubulin and subjected to rigorous quantitative and qualitative analyses. The results showed that a mean of 71.3 +/- 14.3, uniformly spaced, main stromal nerve bundles entered the cornea at the corneoscleral limbus. The bundles averaged 20.3 +/- 7.0 microm in diameter, were separated by a mean spacing of 0.49 +/- 0.40 mm, and entered the cornea at a mean distance of 293 +/- 106 microm from the ocular surface. Each stromal bundle gave rise through repetitive branching to a moderately dense midstromal plexus and a dense subepithelial plexus (SEP). The SEP was comprised of modest numbers of straight and curvilinear nerves, most of which penetrated Bowman's membrane to supply the corneal epithelium, and a more abundant and anatomically complex population of tortuous, highly anastomotic nerves that remained largely confined in their distribution to the SEP. SEP density and anatomical complexity varied considerably among corneas and was less dense and patchier in the central cornea. A mean of 204 +/- 58.5 stromal nerves penetrated Bowman's membrane to supply the central 10 mm of corneal epithelium (2.60 nerves/mm(2)). The density of Bowman's membrane penetrations was greater peripherally than centrally. After entering the epithelium, stromal nerves branched into groups of up to twenty subbasal nerve fibers known as epithelial leashes. Leashes in the central and intermediate cornea anastomosed extensively to form a dense, continuous subbasal nerve plexus, while leashes in the peripheral cornea demonstrated fewer anastomoses and were less complex anatomically. Viewed in its entirety, the subbasal nerve plexus formed a gentle, whorl-like assemblage of long curvilinear subbasal fibers, 1.0-8.0 mm in length, that converged on an imaginary seam or gentle spiral (vortex) approximately 2.51 +/- 0.23 mm inferonasal to the corneal apex. Mean subbasal nerve fiber density near the corneal apex was 45.94 +/- 5.20 mm/mm(2) and mean subbasal and interconnecting nerve fiber diameters in the same region were 1.51 +/- 0.74 microm and 0.69 +/- 0.26 microm, respectively. Intraepithelial terminals originated exclusively as branches of subbasal nerves and terminated in all epithelial layers. Nerve terminals in the wing and squamous cell layers were morphologically diverse and ranged in total length from 9 to 780 microm. The suprabasal layers of the central corneal epithelium contained approximately 605.8 terminals/mm(2). The results of this study provide a detailed, comprehensive description of human corneal nerve architecture and density that extends and refines existing accounts. An accurate, detailed model of the normal human corneal innervation may predict or help to understand the consequences of corneal nerve damage during refractive, cataract and other ocular surgeries.

Control of patterns of corneal innervation by Pax6

PURPOSE

Corneal nerves play essential roles in maintaining the ocular surface through provision of neurotrophic support, but genetic control of corneal innervation is poorly understood. The possibility of a neurotrophic failure in ocular surface disease associated with heterozygosity at the Pax6 locus (aniridia-related keratopathy [ARK]) was investigated.

METHODS

Patterns of corneal innervation were studied during development and aging in mice with different Pax6 dosages and in chimeras. Immunohistochemistry and ELISA-based assays were used to determine the molecular basis of defects seen in Pax6 mutants, and wound healing assays were performed.

RESULTS

In adults, the Pax6(+/-) epithelium was less densely innervated than the wild-type epithelium, and radial projection of epithelial nerves was disrupted. Neurotrophic support of the corneal epithelium appeared normal. Directed nerve projection correlated with patterns of epithelial cell migration in adult wild-types, but innervation defects observed in Pax6(+/-) mice were not fully corrected in wound healing or chimeric models where directed epithelial migration was restored.

CONCLUSIONS

Pax6 dosage nonautonomously controls robust directed radial projection of corneal neurons, and the guidance cues for growth cone guidance are not solely dependent on directed epithelial migration. There is little evidence that ARK represents neurotrophic keratitis.

In vivo laser confocal microscopic analysis of murine cornea and lens microstructures

BACKGROUND AND OBJECTIVE

The purpose of the current study is to investigate in vivo microstructures of anterior segments of normal murine eyes by new-generation in vivo laser confocal microscopy.

MATERIALS AND METHODS

Twenty-six corneas and lenses from 13 mice were analyzed by in vivo laser confocal microscopy.

RESULTS

Murine corneal superficial cells formed a polygonal cell pattern, with a mean cell density of 577 +/- 115 cells/mm2 (mean +/- standard deviation). Corneal basal epithelial cells had dark cytoplasm and were closely organized (9,312 +/- 1,777 cells/mm2). Sub-basal nerve fiber bundles were arranged in a whorl pattern, with both clockwise and counter-clockwise patterns. In the stroma, keratocytes were observed as numerous reflective stellate structures. The endothelial cells were organized in a honeycomb pattern (2,463 +/- 292 cells/mm2). Deeper inside the eye, murine lens epithelial cells were organized in a regular pattern (4,168 +/- 636 cells/mm2) and numerous lens fibers were observed.

CONCLUSION

In vivo laser confocal microscopy can provide high-resolution images of all corneal layers and lens structures of mice without sacrificing animals or tissue preparation.

In vivo confocal microscopy in hydroxychloroquine-induced keratopathy

BACKGROUND

Vortex keratopathy, arising as a side effect of several medications, is characterized by golden-brown deposits in the cornea.

METHODS

A 41-year-old woman treated for sarcoidosis with hydroxychloroquine therapy and suffering from vortex keratopathy was examined by in vivo confocal microscopy. Scans of both corneas were performed.

RESULTS

By slit lamp examination, the left but not the right eye showed a golden-brown deposit throughout the cornea. In vivo confocal microscopy revealed the presence of highly reflective, dot-like intracellular inclusions concentrated in the basal epithelial layer. They were also detected within the anterior and posterior stroma, but not within the endothelium. In regions of the anterior stroma, devoid of inclusions, hyperreflective ramified keratocytes were observed, forming an extended interconnecting network.

CONCLUSION

In addition to the granular deposits, in vivo confocal microscopy revealed hyperreflective, possibly phagocytic keratocytes.

The spark of life: the role of electric fields in regulating cell behaviour using the eye as a model system

Endogenous electric fields (EF) have long been known to influence cell behaviour during development, neural cell tropism, wound healing and cell behaviour generally. The effect is based on short circuiting of electrical potential differences across cell and tissue boundaries generated by ionic segregation. Recent in vitro and in vivo studies have shown that EF regulate not only cell movement but orientation of cells during mitosis, an effect which may underlie shaping of tissues and organs. The molecular basis of this effect is founded on receptor-mediated cell signalling events and alterations in cytoskeletal function as revealed in studies of gene deficient cells. Remarkably, not all cells respond directionally to EF in the same way and this has consequences, for instance, for lens development and vascular remodelling. The physical basis of EF effect may be related to changes induced in 'bound water' at the cell surface, whose organisation in association with trans-membrane proteins (e.g. receptors) is disrupted when EF are generated.

Clinical and In Vivo Confocal Microscopy Findings in Patients Receiving Tamoxifen Citrate

PURPOSE

: To describe the deposition rate of tamoxifen in the cornea and observe its impact on the cornea with confocal microscopy.

METHODS

: Forty-four eyes of 22 women receiving tamoxifen at a dosage of 20 mg/day for at least 6 months for the adjuvant treatment of breast cancer and 30 eyes of 15 healthy age-matched women were examined for corneal drug deposition by slitlamp after pupil dilation. Ultrasound pachymetry, specular microscopy, in vivo confocal microscopy, and Schirmer tear test were also performed in all patients.

RESULTS

: The mean duration of tamoxifen intake was 21.6 +/- 7.9 months (range, 13-44 months), and the mean cumulative dose was 12.9 +/- 4.7 g (range, 7.8-26.4 g). Drug depositions in the inferior paracentral cornea were identified in 32 (72%) eyes at pupil-dilated slitlamp examination. There were no significant differences between eyes with keratopathy, those without keratopathy, and control eyes in regard to the mean Schirmer test scores, mean central corneal thickness, mean endothelial cell count, mean basal epithelium cell density, mean anterior and posterior stromal keratocyte density, and mean endothelial cell density (P > 0.05). No pathologic alteration of structure was observed with in vivo confocal microscopy at any corneal level in patients receiving tamoxifen.

CONCLUSIONS

: Low-dose tamoxifen use was associated with corneal depositions in 72% of patients. Slitlamp examination performed with pupil dilation was helpful in detection of subtle tamoxifen-related deposits. Amelioration of in vivo confocal microscopy systems may be helpful in accurate imaging of the paracentral and peripheral cornea.

Mycobacterium abscessus keratitis after LASIK with IntraLase femtosecond laser

A healthy 38-year-old woman developed 2 white spots in her left eye 2 weeks after bilateral laser in situ keratomileusis (LASIK) using the IntraLase femtosecond laser. Initial treatment included levofloxacin 0.5% but was unsuccessful. The surgeon irrigated the interface and repositioned the flap due to a worsened lesion. She was referred to us after the keratitis had not improved. The flap was lifted for collection of the specimen and irrigation of the interface. The keratitis was treated with intensive topical clarithromycin 1%, amikacin 1.25% and oral clarithromycin, which improved her clinical condition. She developed a toxic reaction to amikacin 1.25%, which was replaced by moxifloxacin 0.5%. Mycobacterium abscessus was identified. The keratitis resolved over 2 months. Five months after treatment, the patient had a visual acuity of 20/20 with correction. Nontuberculous mycobacteria should be considered as an etiologic agent, even in cases of infectious keratitis after LASIK using the femtosecond laser.

Drug-induced corneal complications

PURPOSE OF REVIEW

To review the common corneal manifestations of systemic medications in order to describe the characteristic clinical features associated with particular systemic drugs, the indications for drug cessation, and the risks for irreversible ocular toxicity.

RECENT FINDINGS

Systemic medications may reach the cornea via the tear film, aqueous humor, and limbal vasculature. The corneal changes are often the result of the underlying chemical properties of medications. Amphiphilic medications (amiodarone, chloroquine, suramin, clofazimine, etc.) may produce a drug-induced lipidosis and development of a vortex keratopathy. Antimetabolites (cytarabine) may lead to a degeneration of basal epithelial cells with formation of epithelial microcysts. Additionally, systemically administered medications and drug metabolites may lead to a stromal or endothelial deposition. Corneal changes may result in reduced visual acuity, photophobia, and ocular irritation, though these symptoms typically resolve following drug cessation. Corneal manifestations of systemic medications are often dose related, and may reflect the potential risk for lenticular or retinal changes.

SUMMARY

Corneal changes secondary to systemic medications may affect all layers of the cornea. While corneal deposition is typically not an indication for drug cessation, patients receiving particular medications should be monitored for symptoms related to corneal deposition as well as for signs of irreversible ocular toxicity.

Sodium hyaluronate (hyaluronic acid) promotes migration of human corneal epithelial cells in vitro

PURPOSE

Sodium hyaluronate (hyaluronic acid) is known to promote corneal epithelial wound healing in vivo and in vitro, in animal experiments. Sodium hyaluronate is the ligand for CD44, a cell surface adhesion molecule which has been found on normal human corneal epithelial cells. The purpose of this study was to investigate the effect of sodium hyaluronate on human corneal epithelial cell migration, proliferation, and CD44 receptor expression.

METHODS

Human corneal epithelial cell cultures were established from 32 donor corneoscleral rims and maintained separately in three different culture conditions: (1) culture medium only, (2) sodium hyaluronate enriched (0.6 mg/ml) medium, and (3) hydroxypropylmethylcellulose enriched (2.5 mg/ml) medium. The total area of migrating epithelial cell sheets in each case was measured by planimetry on days 4, 8, 12, and 16. Cytospin preparations of cells cultured in the different culture conditions were examined immunohistochemically for proliferation and CD44 receptor expression using antibodies directed against Ki67 and CD44 respectively.

RESULTS

Cells cultured in the presence of sodium hyaluronate showed significantly increased migration at days 12 and 16 (Friedmen test: p = 0.0012, day 16; p = <0.001, day 12) compared with cells cultured in the other media. There was no difference in cell proliferation (Ki67) or CD44 expression on cells cultured in the different culture conditions.

CONCLUSIONS

Sodium hyaluronate promotes migration but not proliferation or CD44 expression on human corneal epithelial cells in vitro. The beneficial effect of sodium hyaluronate in corneal wound healing is likely to be related to rapid migration of cells leading to rapid wound closure. This may be facilitated by the adhesion between CD44 on the cells and hyaluronic acid, which coats the surface of the denuded cornea.

Ocular surface epithelium induces expression of human mucosal lymphocyte antigen (HML-1) on peripheral blood lymphocytes

BACKGROUND/AIMS

Peripheral blood CD8+ lymphocytes that home to mucosal surfaces express the human mucosal lymphocyte antigen (HML-1). At mucosal surfaces, including the ocular surface, only intraepithelial CD8+ lymphocytes express HML-1. These lymphocytes are retained in the intraepithelial compartment by virtue of the interaction between HML-1 and its natural ligand, E-cadherin, which is expressed on epithelial cells. The purpose of this study was to determine whether ocular surface epithelial cells (ocular mucosa) could induce the expression of human mucosal lymphocyte antigen on peripheral blood lymphocytes.

METHODS

Human corneal and conjunctival epithelial cells were co-cultured with peripheral blood lymphocytes. Both non-activated and activated lymphocytes were used in the experiments. After 7 days of incubation, lymphocytes were recovered and analysed for the antigens CD8/HML-1, CD4/HML-1, CD3/CD8, CD3/CD4, CD3/CD25, CD8/CD25, and CD4/CD25 by flowcytometry.

RESULTS

Significant statistical differences were observed in the CD8/HML-1 expression when conjunctival epithelial cells were co-cultured with non-activated and activated lymphocytes (p = 0.04 for each) and when corneal epithelial cells were co-cultured with non-activated lymphocytes (p = 0.03). Significant statistical difference in CD4/HML-1 expression was observed only when conjunctival epithelial cells were co-cultured with activated lymphocytes (p = 0.02).

CONCLUSION

Ocular surface epithelial cells can induce the expression of human mucosal lymphocyte antigen on CD8+ (and to some extent on CD4+) lymphocytes. This may allow the retention of CD8+ and CD4+ lymphocytes within the epithelial compartment of the conjunctiva and play a part in mucosal homing of lymphocytes.

Clonal analysis of patterns of growth, stem cell activity, and cell movement during the development and maintenance of the murine corneal epithelium

Patterns of growth and cell movement in the developing and adult corneal epithelium were investigated by analysing clonal patches of LacZ-expressing cells in chimeric and X-inactivation mosaic mice. It was found that cell proliferation throughout the basal corneal epithelium during embryogenesis and early postnatal life creates a disordered mosaic pattern of LacZ(+) clones that contrasts with patterns of proliferation and striping produced during the later embryonic stages of retinal pigmented epithelium development. The early mosaic pattern in the corneal epithelium is replaced in the first 12 postnatal weeks by an ordered pattern of radial stripes or sectors that reflects migration without mixing of the progeny of clones of limbal stem cells. In contrast to previous assumptions, it was found that maturation of the activity of limbal stem cells and the pattern of migration of their progeny are delayed for several weeks postnatally. No evidence was found for immigration of the progeny of stem cells until the 5th postnatal week. There are approximately 100 clones of limbal stem cells initially, and clones are lost during postnatal life. Our studies provide a new assay for limbal and corneal defects in mutant mice.

Clinical course of hurricane keratopathy

BACKGROUND/AIMS

"Hurricane keratopathy" is the name given to the whorl pattern, highlighted with fluorescein, seen in situations where corneal epithelial cell turnover is exaggerated. Although the condition is well described, follow up data on patients with this condition and its sequelae have only been reported in corneal graft patients. The aim was to study the clinical course of hurricane keratopathy in corneal graft patients and contact lens wearers, and to document any sequelae of this condition.

METHODS

Hurricane keratopathy, occurring in 20 eyes with corneal grafts and 16 eyes (six bilateral) wearing rigid gas permeable contact lenses, was studied and followed. The occurrence, pattern, progress, resolution, and residual effects of the whorls were noted.

RESULTS

Hurricane keratopathy was noted to occur in grafts as previously reported and also in contact lens wearers, which has hitherto not been reported. The whorls usually appeared within the first 3 weeks postoperatively and persisted up to 4 months. A small epithelial defect (11.1%), heaped epithelial cells (5.6%), and a nebular grade opacity (2.8%), were the only significant sequelae noted at the epicentre of the whorls. Resolution occurred from the periphery towards the centre of the cornea.

CONCLUSIONS

The whorl pattern is sustained as long as the stimulus for increased cell turnover is maintained. Once this stimulus is eliminated, the pattern tends to resolve spontaneously.