Normal Conjunctival Epithelium Research Articles

Intermediate filament expression by normal and diseased human corneal epithelium

Cicatricial conjunctivitis may be a sequel to systemic disorders (eg, Stevens-Johnson syndrome, cicatricial pemphigoid) or local disorders such as chemical burns. The cicatrisation is often associated with corneal epithelial changes that cause visual loss. These have been attributed to encroachment of the conjunctival epithelium over the cornea. However, the epithelial anomalies are poorly understood. We investigated the corneal epithelial changes in cicatricial conjunctivitis with an immunohistochemical study of intermediate filaments in normal and pathological specimens. Our results show that the normal corneal epithelium is immunoreactive for cytokeratin 3 (CK 3) but not cytokeratin 19 (CK 19), whereas normal conjunctival epithelium is CK 3 negative and CK 19 positive. Conjunctiva artificially transposed over the cornea (after therapeutic conjunctival flap reconstruction) retained the normal pattern of conjunctival cytokeratin expression (CK 3 negative, CK 19 positive). Conversely, the entire corneal epithelium exhibited the normal cytokeratin pattern (CK 3 positive, CK 19 negative) in 82% of Stevens-Johnson, 80% of cicatricial pemphigoid, and 69% of chemical burns specimens. The findings suggest that conjunctival encroachment is not responsible for the changes at the corneal surface in cicatricial conjunctivitis and that the abnormal corneal epithelium is derived from native corneal cells in these diseases.

Biological activity of N-(4-hydroxyphenyl) retinamide-O-glucuronide in corneal and conjunctival cells of rabbits and humans.

Previous studies of topical retinoic acid for treatment of ocular surface disease met with limited success due to instability and irritancy of the retinoid and lack of efficacy in keratoconjunctivitis sicca. There has, however, been continued interest in the treatment of mucin deficiency and cicatrizing conjunctival diseases, such as ocular cicatricial pemphigoid (OCP), topically with retinoids. In this study the biological activity of stable, water-soluble, synthetic retinoid, N-(4-hydroxyphenyl) retinamide-O-glucuronide (4-HPROG) was investigated in vivo and in vitro using conjunctival and corneal epithelium and fibroblasts. Vitamin A-deficient rabbits with stage 3-4 corneal xerosis and squamous metaplasia confirmed by conjunctival impression cytology were treated with topical 0.1% 4-HPROG in an artificial tear vehicle for 3 weeks. Impression cytology was repeated at 2 and 3 weeks and at 3 weeks conjunctival biopsies were fixed for histology. Growth curves were generated using conjunctival fibroblasts of rabbits and humans (normals and patients with cicatrizing conjunctival disease including OCP and Stevens-Johnson syndrome) cultured in the 10(-8)-10(-6) M 4-HPROG. In vivo, corneal xerosis cleared in three days. A normal conjunctival epithelium was restored by 2 weeks and goblet cells were present by 3 wk, with no change in vehicle-treated controls. No ocular irritation occurred. In vitro, 10(-6) M 4-HPROG inhibits growth of rabbit conjunctival fibroblasts. The retinoid had no effect on proliferation of conjunctival fibroblasts from normal humans but the doubling time of cells from patients with OCP increased significantly, from 50.9 +/- 10.01 h (control) to 61.5 +/- 8.95 h (retinoid). Proliferation of conjunctival fibroblasts from a patient with Stevens-Johnson syndrome was also inhibited. N-(4-hydroxyphenyl) retinamide-O-glucuronide is biologically active and merits further study to determine its efficacy in controlling conjunctival fibrosis and treating ocular surface squamous metaplasia.

Mast cell distribution and neutral protease expression in acute and chronic allergic conjunctivitis

Allergic eye disease has a variety of clinical manifestations including seasonal atopic conjunctivitis (SAC), perennial atopic conjunctivitis (PAC), atopic keratoconjunctivitis (AKC), and atopic blepharoconjunctivitis (ABC). We have investigated the number, distribution and protease expression of mast cells in normal and diseased conjunctiva with the use of immunohistochemistry in water-miscible resin sections. The median mast cell densities in normal subjects were 17 mm-2 in the bulbar substantia propria and 9 mm-2 in tarsal substantia propria. Mast cells were absent from the normal conjunctival epithelium at both sites. Mast cell densities were increased in the bulbar substantia propria in SAC, AKC and ABC. Tarsal substantia propria showed a significant increase in mast cells in ABC and AKC disease states. Mast cells express a range of proteases which varies according to their anatomic site. Mast cells in connective tissue are described to contain tryptase, chymase, cathepsin-G and carboxypeptidase-A, whereas mucosal mast cells contain only tryptase. In the diseased conjunctiva there was a marked reduction in proteases other than tryptase in the intraepithelial mast cells. There were also significant reductions in protease expression other than tryptase in the bulbar substantia propria in AKC and ABC. There appear to be specific alterations in the distribution of mast cells in the sub-categories of allergic eye disease. The distinction between mucosal and connective tissue mast cell phenotypes is not clear-cut and may depend on the functional state of the mast cells in relation to the microenvironment.

Patterns of cytokeratin expression in impression cytology specimens from normal human conjunctival epithelium.

The cytokeratins are a category of intermediate filaments characteristically found in epithelial cells. Approximately 20 cytokeratins have thus far been described and their normal pattern of expression appears to be dependent on cell-type and differentiation state. Moreover, in each epithelial cell type, a distinct subset of cytokeratin polypeptides will be present. Patterns of cytokeratin expression have been shown to change secondary to altered microenvironmental conditions (e.g. disease states) and these changes have become useful in diagnostic pathology. To this end, cytokeratin expression patterns in the various human epithelia, both normal and diseased, have been extensively examined. However, similar studies in the conjunctival epithelium are sparse and generally have examined non-human, cultured or limbal conjunctival epithelium and/or have used a limited panel of cytokeratin markers.

Ocular Manifestations and Impression Cytology of Anorexia Nervosa

A prospective age- and sex-controlled study of seven anorexia nervosa patients and seven normal control patients was conducted to determine the ocular manifestations of anorexia nervosa. Slit-lamp examination of the anorexic patients demonstrated a high incidence (4/7) of multiple episcleral capillary aneurysms and subconjunctival hemorrhages. Two of seven anorexia nervosa patients had bilateral superficial punctate keratopathy. Anesthetized Schirmer tear testing demonstrated a significantly (P < 0.005) reduced mean tear production in the anorexia nervosa group (11.3 mm) compared with the control group (22.4 mm). Masked interpretation of conjunctival impression cytology demonstrated moderate to severe conjunctival squamous metaplasia in the majority of the anorexia nervosa group (5/7) compared to normal conjunctival epithelium in the majority of the control group (5/7). Absence of nyctalopia, Bitot's spots, and xerosis, and lack of conjunctival goblet cell loss indicate that the anorexia nervosa group did not have vitamin A deficiency.

Dacryoadenoma: A Unique Tumor of the Conjunctival Epithelium

For 15 years, a 48-year-old woman had been aware of a pinkish translucent inferior epibulbar mass toward the fornix that was stationary in size. Light microscopic evaluation of the excised specimen showed that it was a gland-forming benign tumor. It originated from the surface epithelium by the downward invagination of tubular formations that underwent secondary and tertiary ramifications. The surface epithelium overlying the mass was not normal conjunctival squamous epithelium, but it was a modification in the form of a superficial layer of columnar to cuboidal cells surmounting several nuclei similar to the cells lining the subepithelial lumen-forming units. Electron microscopy showed that both the surface and tumor epithelium contained apical lacrimaltype zymogen granules and basilar whorls of rough-surfaced endoplasmic reticulum. Scattered myoepithelial cells were associated with the acinar-type epithelium of the tumor, and there were goblet cells intermixed. Neither light nor electron microscopy disclosed the presence of true ducts. The authors conclude that the lesion was a benign proliferation of lacrimal secretory-type cells and suggest the term “dacryoadenoma” for this previously undescribed entity.

Autoimmune Phenomena of the Conjunctiva and Cornea

A 20-year-old woman had erosions of the corneal and conjunctival epithelium and sterile stromal ulcerations of the cornea necessitating multiple corneal grafts, which were unsuccessful. An immunopathological basis for her disease was suggested by the demonstration of tissue-fixed antibodies and complement in her own conjunctival epithelium by direct immunofluorescence. In addition, circulating antibodies to normal corneal and conjunctival epithelium were demonstrated in the patient's serum by indirect immunofluorescent techniques and the titer of circulating antibodies was found to correlate with disease activity. The involvement of the fellow eye after evisceration of the first eye and reduction of systemic steroids in association with a greatly elevated level of circulating antibodies provided additional evidence for an autoimmune process. A background of immunological susceptibility was found in the patient and her family by history and immunological examination.