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PubMed2002

Comparative analysis of telomere lengths and erosion with age in human epidermis and lingual epithelium.

We investigated progressive telomere shortening in normal human epidermis and lingual epithelium during aging, and attempted, in particular, to ascertain whether the telomere shortening that accompanies aging occurs at the same rate in different tissues. We studied telomeric DNA integrity, and estimated annual telomere loss, in 52 specimens of epidermis and 48 specimens of lingual epithelium collected at autopsy from subjects who had died at ages between 0 and 101 y. Most of the DNA samples were measured twice by southern blot hybridization. In addition, the correlation between telomere lengths in the two types of tissues was examined. The telomere reduction rates in epidermis and lingual epithelium were 36 bp and 30 bp per y, respectively, and these were significantly different. The rates obtained by the second measurements in epidermis and lingual epithelium were 39 and 32 bp per y, respectively, and these were also significantly different. The mean telomere lengths in the epidermis of eight neonates and the lingual epithelium of seven neonates were 13.2+/-1.0 and 13.8+/-1.0 kb, respectively. Comparison of telomere lengths in the two tissues for 41 paired samples showed that the mean telomere length in the epidermis (10.7+/-2.3 kb) was less than that in the lingual epithelium (12.4+/-2.5 kb); however, statistical analysis revealed a very significant relationship between epidermal and lingual epithelial telomere length (r=0.842, p<0.0001). These results indicate that the telomeres in epidermis and lingual epithelium are characterized by tissue-specific loss rates.

Adolescent↗
PubMed2001

Preferential repair by squamous epithelium of thermal induced injury to the proximal stomach in patients undergoing ablation of Barrett's esophagus.

BACKGROUND: The presence of extensions of squamous epithelium into the proximal stomach in patients undergoing routine upper endoscopy has recently been described. The factors that may favor development of squamous epithelium within the proximal stomach remain unknown. METHODS: Patients with Barrett's esophagus who agreed to undergo ablation of Barrett's epithelium by using multipolar electrocoagulation were included. Patients were treated with a high dose of a proton pump inhibitor. The columnar-appearing mucosa was systematically treated. Occasionally, thermal injury was inadvertently induced in the proximal stomach. On endoscopy performed 4 to 6 weeks after treatment, the presence of squamous epithelium extending into the proximal stomach was documented. The use of Lugol's stain assisted in confirming the squamous nature of the abnormal tissue, which was confirmed histologically by cytokeratin immunohistochemistry. RESULTS: The 12 patients included in the study had a mean length of Barrett's epithelium of 3.8 +/- 0.7 cm. Patients were treated with omeprazole, mean dose 66 +/- 6.0 mg, and had a mean percent total time that the pH was less than 4 of 1.9 +/- 0.8. The mean length and width of gastric squamous extensions were 1.7 +/- 0.2 cm and 0.8 +/- 0.1 cm, respectively. None of the squamous extensions into the stomach were documented before mucosal ablation. The extensions stained positively for cytokeratin 13 and negatively for cytokeratin 8, thereby confirming their squamous nature. CONCLUSIONS: Thermal injury to the proximal stomach in patients undergoing ablation of Barrett's epithelium and profound acid suppression results in repair by squamous epithelium. Recognition of this lesion is essential because it may lead to confusion as to the location of the esophagogastric junction in subsequent endoscopic evaluations.

Adult↗
PubMed1995

Deletion of high-avidity T cells by thymic epithelium.

Tolerance induction by thymic epithelium induces a state of so-called "split tolerance," characterized in vivo by tolerance and in vitro by reactivity to a given thymically expressed antigen. Using a model major histocompatibility complex class I antigen, H-2Kb (Kb), three mechanisms of thymic epithelium-induced tolerance were tested: induction of tolerance of tissue-specific antigens exclusively, selective inactivation of T helper cell-independent cytotoxic T lymphocytes, and deletion of high-avidity T cells. To this end, thymic anlagen from Kb-transgenic embryonic day 10 mouse embryos, taken before colonization by cells of hemopoietic origin, were grafted to nude mice. Tolerance by thymic epithelium was not tissue-specific, since Kb-bearing skin and spleen grafts were maintained indefinitely. Only strong priming in vivo could partially overcome the tolerant state and induce rejection of some skin grafts overexpressing transgenic Kb. Furthermore, the hypothesis that thymic epithelium selectively inactivates those T cells that reject skin grafts in a T helper-independent fashion could not be supported. Thus, when T-cell help was provided by a second skin graft bearing an additional major histocompatibility complex class II disparity, tolerance to the Kb skin graft was not broken. Finally, direct evidence could be obtained for the avidity model of thymic epithelium-induced negative selection, using Kb-specific T-cell receptor (TCR) transgenic mice. Thymic epithelium-grafted TCR transgenic mice showed a selective deletion of those CD8+ T cells with the highest density of the clonotypic TCR. These cells presumably represent the T cells with the highest avidity for Kb. We conclude that split tolerance induced by thymic epithelium was mediated by the deletion of those CD8+ T lymphocytes that have the highest avidity for antigen.

Animals↗
PubMed1999

Identification of a cytosolic NADP+-dependent isocitrate dehydrogenase that is preferentially expressed in bovine corneal epithelium. A corneal epithelial crystallin.

Recently, metabolic enzymes have been observed in both the lens and corneal epithelium at levels greatly exceeding what is necessary for normal metabolic functions. These proteins have been termed taxon-specific crystallins and are thought to play a role in maintaining tissue transparency. We report here that cytosolic NADP+-dependent isocitrate dehydrogenase (ICDH) represents a new corneal crystallin. Using suppression subtractive hybridization, we identified a gene (with a deduced amino acid sequence that showed 94% identity to rat cytosolic NADP+-dependent ICDH) that is preferentially expressed in bovine corneal epithelium. Northern blots established that its mRNA level in the corneal epithelium was 31-, 39-, 133-, 230-, and 929-fold more than in the liver, bladder epithelium, stomach epithelium, brain, and heart, respectively. This mRNA was detected primarily in corneal epithelial basal cells by in situ hybridization. SDS-polyacrylamide gel electrophoresis, two-dimensional gel analysis, and Western blotting showed that this protein was overexpressed in the corneal epithelium, constituting approximately 13% of the total soluble bovine corneal epithelial proteins. Enzyme assays showed a corresponding overabundance of this protein in bovine corneal epithelium. Taken together, these data indicate that bovine cytosolic ICDH fulfills the criteria for a corneal epithelial crystallin and may be involved in maintaining corneal epithelial transparency.

Amino Acid Sequence↗
PubMed2005

Laminin alpha5 is required for dental epithelium growth and polarity and the development of tooth bud and shape.

In tooth development, the oral ectoderm and mesenchyme coordinately and reciprocally interact through the basement membrane for their growth and differentiation to form the proper shape and size of the tooth. Laminin alpha5 subunit-containing laminin-10/11 (LM-511/521) is the major laminin in the tooth germ basement membrane. Here, we have examined the role of laminin alpha5 (Lama5) in tooth development using laminin alpha5-null mouse primary dental epithelium and tooth germ organ cultures. Lama5-null mice develop a small tooth germ with defective cusp formation and have reduced proliferation of dental epithelium. Also, cell polarity and formation of the monolayer of the inner dental epithelium are disturbed. The enamel knot, a signaling center for tooth germ development, is defective, and there is a significant reduction of Shh and Fgf4 expression in the dental epithelium. In the absence of laminin alpha5, the basement membrane in the inner dental epithelium becomes discontinuous. In normal mice, integrin alpha6beta4, a receptor for laminin alpha5, is strongly localized at the basal layer of the epithelium, whereas in mutant mice, integrin alpha6beta4 is expressed around the cell surface. In primary dental epithelium culture, laminin-10/11 promotes cell growth, spreading, and filopodia-like microspike formation. This promotion is inhibited by anti-integrin alpha6 and beta4 antibodies and by phosphatidylinositol 3-kinase inhibitors and dominant negative Rho-GTPase family proteins Cdc42 and Rac. In organ culture, anti-integrin alpha6 antibody and wortmannin reduce tooth germ size and shape. Our studies demonstrate that laminin alpha5 is required for the proliferation and polarity of basal epithelial cells and suggest that the interaction between laminin-10/11-integrin alpha6beta4 and the phosphatidylinositol 3-kinase-Cdc42/Rac pathways play an important role in determining the size and shape of tooth germ.

Animals↗
PubMed2000

Isolation and characterization of a Ca(2+)-activated chloride channel from human corneal epithelium.

PURPOSE: Transparency of the cornea is maintained through the activity of secretory mechanisms in the epithelium and endothelium, which offset the tendency of the stroma to imbibe fluid and swell. These secretory mechanisms establish osmotic gradients thereby providing the osmotic driving forces for coupled fluid transport from the stroma into both the tears and the anterior chamber. To further characterize the mechanism of epithelial Cl secretion, we cloned a cDNA encoding a Ca(2+)-dependent chloride channel, an abundant mRNA in human corneal epithelium. We investigated the abundance of all known human chloride channels in corneal epithelium to identify those responsible for regulating chloride conductance in this tissue. METHODS: For the isolation of a full-length cDNA clone, a probe was selected from a set of expressed sequenced tag (EST) clones classified as unique to corneal epithelium (http://bodymap. ims.u-tokyo.ac.jp). The expression patterns of the corresponding gene encoding novel chloride channel gene in human cornea and other tissues were examined by reverse transcription-polymerase chain reaction (RT-PCR). Quantitative PCR was performed to clarify the expression level of the novel chloride channel gene in cornea relative to that in other human tissues. RESULTS: We cloned a new Ca(2+)-activated chloride channel, CLCA2, from corneal epithelium. The full length cDNA clone encoded 943 amino acids with 62% identity to bovine Ca(2+)-activated chloride channel. The CLCA2 gene mapped to human chromosome 1p32. Quantitative expression analysis by RT-PCR showed that it is the most abundant chloride channel in corneal epithelium. CONCLUSION: High and tissue specific expression of the CLCA2 gene in human corneal epithelium implies an important role in corneal transparency maintenance.

Amino Acid Sequence↗
PubMed1998

Epithelium-dependent regulation of airways smooth muscle function. A histamine-nitric oxide pathway.

The airway epithelium is responsible for the production of a number of arachidonic acid and non-prostanoid inhibitory factors. Epithelium synthesises nitric oxide (NO) which may be important in regulating the function of airways smooth muscles. We studied in vitro the effect of histamine (100 nM-100 microM) which increases the NO release on rabbit airway smooth muscles induced by 80 mM KC1 in the presence or not of 10(-5) Methylene blue (MB) (inactivator of guanylate cyclase) or N(G)-monomethyl L-arginine (L-NMMA), a NOS inhibitor. All experiments were done in tracheal muscle strips from 28 rabbits with epithelium and after epithelium removal. The additional use of histamine (1 microM) on KC1 contraction induced a relaxation of 10% of the initial contraction. The additional use of L-NMMA decreased the relaxation to 5% of initial contraction. MB rather than L-NMMA increased the contraction significantly (p<0.01). Epithelium removal increased the contraction induced by KC1 (80 mM) and histamine (1 microM) by about 30% (p<0.001). NO release especially from epithelium regulates the airways smooth muscle functions. Damage to the epithelium may contribute to an increase in airways sensitivity, observed in asthma.

Animals↗
PubMed1962

Electron microscopy of the uterine epithelium in the rabbit.

The ultrastructure of the uterine epithelium has been studied in estrous, ovariectomized, pregnant, and pseudopregnant rabbits. Tissue for light microscopy was fixed in Bouin's solution and stained with hematoxylin and eosin, by the periodic acid-Schiff (PAS) method, and with methylene blue. Tissue for electron microscopy was fixed in 1 per cent osmium tetroxide in White's saline and embedded in Araldite. The uterine epithelium in estrus is comprised of ciliated and non-ciliated cells. After ovariectomy the epithelium becomes reduced in height and PAS-positive material disappears. Multinucleated cells are formed in the epithelium in pregnancy, pseudopregnancy, and in the non-pregnant horn in unilateral pregnancy. They degenerate during the 3rd week of pseudopregnancy and during the 4th week of pregnancy in the non-pregnant horn. The formation of multinucleated cells is believed to be under hormonal control. The uterine epithelium in contact with the blastocyst changes into a "symplasma," presumably under the influence of a local (chemical?) effect produced by the blastocyst. This change is not seen in pseudopregnancy nor in the non-pregnant horn in unilateral pregnancy. A complex infolding of the basal cell membrane of the epithelium accompanies the "symplasmic" change. The remaining uterine epithelium in pregnancy shows a well developed ergastoplasm suggesting a production of secretion materials, some of which may be available for absorption by the fetus through the yolk sac or paraplacental chorion.

Animals↗
PubMed1979

Electrical properties of an excitable epithelium.

The exumbrellar epithelium of the hydromedusa, Euphysa japonica, is composed of a single layer of broad (70 micrometers), thin (1--2 micrometers) cells which are joined by gap junctions and simple appositions. Although the epithelium lacks nerves, it is excitable; electrically stimulating the epithelium initiates a propagated action potential. The average resting potential of the epithelial cells is -46 mV. The action potential, recorded with an intracellular electrode, is an all-or-nothing, positive, overshooting spike. The epithelial cells are electrically coupled. The passive electrical properties of the epithelium were determined from the decrement in membrane hyperpolarization with distance from an intracellular, positive current source. The two-dimensional space constant of the epithelium is 1.3 mm, the internal longitudinal resistivity of the cytoplasm and intercellular junctions is 196 omega cm, and the resistivity of both apical and basal cell membranes is greater than 23 k omega cm2. Although the membrane resistivity is high, the transverse resistivity of the epithelium is quite low (7.5 omega cm2), indicating that the epithelium is leaky with a large, transverse, paracellular shunt.

Action Potentials↗
PubMed1994

Evaluation of the respiratory epithelium of normals and individuals with cystic fibrosis for the presence of adenovirus E1a sequences relevant to the use of E1a- adenovirus vectors for gene therapy for the respiratory manifestations of cystic fibrosis.

Lung disease associated with disorders such as cystic fibrosis (CF) may be amenable to somatic gene therapy in which there is delivery of the normal gene directly to the respiratory epithelium using E1a- adenovirus (Ad) type 2- or 5-based vectors. For safety reasons, the Ad vectors are rendered replication deficient by deletion of the E1a region. Because there is the theoretical possibility of an E1a- replication-deficient vector replicating as a result of recombination or complementation with Ad 2/5 E1a sequences present in the target cell, this study is directed toward evaluating respiratory epithelium of normals and individuals with CF for the presence of E1a sequences. Using Ad 2/5 E1a-specific primers and the polymerase chain reaction to evaluate DNA recovered from freshly isolated nasal and bronchial epithelium recovered by brushing, E1a sequences were detected in respiratory epithelium of 19 of 91 normals (21%). In the E1a-positive samples, the average of E1a copy number was 55 +/- 18/10(3) recovered cells. In CF individuals, 7 of 52 (13%) had detectable E1a sequences in the respiratory epithelium, with E1a copy number in the positive samples of 80 +/- 21/10(3) recovered cells. These results demonstrate that there are detectable Ad 2/5 E1a sequences in the respiratory epithelium of a small percentage of normals and individuals with CF. Because of the theoretical potential of such sequences supporting replication of E1a- Ad vectors, human gene therapy protocols for CF utilizing such vectors should consider evaluating study individuals for the presence of Ad 2/5 E1a sequences in the respiratory epithelium.

Adenoviridae Infections↗
PubMed1986

Epidermoid metaplasias of xenotransplanted human tracheobronchial epithelium.

Repopulation of rat tracheas of human tracheobronchial epithelial cells obtained from intermediate autopsies was achieved by introducing into de-epithelialized rat tracheas either pieces of donor tissue containing respiratory mucosa or epithelial cells produced by an in vitro amplification of these cells. After tracheas were sealed, and transplanted into the subcutaneous tissues of nude mice, a newly formed epithelium migrated over the denuded luminal surface. During this process, regenerative epidermoid metaplasias, consisting of the growth of thin stratified epithelium with keratinization but without atypia was observed. Four weeks after xenotransplantation, most of the luminal surface was covered by columnar epithelium with occasional patches of epidermoid metaplasia. When this epithelium was exposed to 7,12-dimethylbenzo[a]anthracene (DMBA) a thick epidermoid metaplasia with mild to moderate atypia was observed. This type of epithelium is seen one to three months after insertion of the DMBA-containing pellets into the tracheal lumen. Immunohistochemical staining with antikeratin monoclonal antibodies AE1 and AE3 revealed increased immunostaining in both regenerative and DMBA-induced metaplasias compared with that of untreated normal mucociliary epithelium. Although no differences between the two types of metaplasias were detected with AE1 and AE3, the use of involucrin immunostain showed important differences. Normal respiratory epithelium did not contain involucrin, but this protein was seen in the surface layer of regenerative epidermoid metaplasias. In DMBA-induced metaplasias, involucrin was found not only in the superficial cells but was also present in numerous suprabasal cells. The hyperplastic nature of these carcinogen-induced lesions, together with the presence of cellular atypia and an altered involucrin distribution pattern, suggest a preneoplastic state.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2002

Progestin-induced apoptosis in the Macaque ovarian epithelium: differential regulation of transforming growth factor-beta.

BACKGROUND: Oral contraceptive (OC) use is associated with a reduced risk of ovarian cancer. An OC component, progestin, induces apoptosis in the primate ovarian epithelium. One regulator of apoptosis is transforming growth factor-beta (TGF-beta). We determined the effect of progestin on TGF-beta expression in the primate ovarian epithelium and examined the relationship between TGF-beta expression and apoptosis. METHODS: Female cynomolgus macaques were randomly assigned to receive a diet for 35 months containing no hormones (n = 20); the OC Triphasil (n = 17); or each of its constituents, ethinyl estradiol (estrogen, n = 20) or levonorgestrel (progestin, n = 18 ), alone. Ovarian sections were immunostained with monoclonal antibodies against TGF-beta1 or TGF-beta2 plus TGF-beta3 (TGF-beta2/3) isoforms. The expression of TGF-beta isoforms in four ovarian compartments (epithelium, oocytes, granulosa cells, and hilar vascular endothelium) was compared among treatment groups. The association between TGF-beta expression and apoptosis, as determined by morphology and histochemistry, was examined in ovarian epithelium. All statistical tests were two-sided. RESULTS: Compared with ovaries from the control and estrogen-only-treated monkeys, the ovaries of progestin-treated monkeys showed 1) a marked decrease in the expression of TGF-beta1 and a concomitant increase in the expression of the TGF-beta2/3 isoforms in the ovarian epithelium (P<.001), 2) an increase in the expression of TGF-beta2/3 in the hilar vascular endothelium (P<.001), and 3) a marked decrease in TGF-beta2/3 expression in granulosa cells (P<.001). The apoptotic index of the ovarian epithelium was highly associated with the change in expression from TGF-beta1 (P<.001) to TGF-beta2/3 (P</=.002) induced by progestin treatment. CONCLUSIONS: Progestin induces differential regulation in the ovarian epithelium of TGF-beta, a change in the expression of which is highly associated with apoptosis. These data suggest a possible biologic mechanism for the protective association between OC use and reduced ovarian cancer risk.

Animals↗
PubMed1997

The relaxant effect of ketamine on guinea pig airway smooth muscle is epithelium-independent.

Airway epithelial cells and vascular endothelial cells modulate the tone of the underlying smooth muscle by releasing relaxing factors such as prostanoids and nitric oxide (NO). In the present study, we investigated whether the relaxant effect of ketamine depends on any of the epithelium-derived relaxing factors. Tracheae of female guinea pigs were cut spirally into strips (15 x 3 mm) and mounted in water-jacketed organ baths filled with Krebs-bicarbonate buffer aerated with a mixture of 95% O2 and 5% CO2 at 37 degrees C. Changes in the tension of the strips were measured isometrically with a force displacement transducer and recorded with a polygraph. In the first set of experiments, we examined the effect of ketamine on the concentration-response curves for histamine and carbachol in strips in which the epithelium was kept intact and in strips with denuded epithelium. In the second and third set of experiments, we studied the effect of indomethacin, a cyclooxygenase inhibitor, and N-omega-nitro-L-arginine methylester(L-NAME), a NO synthase inhibitor, on the relaxant activity of ketamine on tracheal strips contracted by histamine or carbachol. The following results were obtained: 1. Mechanical denudation of the tracheal epithelium shifted the concentration-response curve for histamine to the left (the 50% effective concentration [EC50] value of histamine decreased from 3.5 +/- 0.02 x 10(-6) M in the intact strips to 0.98 +/- 0.01 x 10(-6) M in denuded strips, P < 0.001). However, removal of the tracheal epithelium did not change the response to carbachol (the EC50 for carbachol was 1.1 +/- 0.02 x 10(-7) M in intact strips versus 0.88 +/- 0.01 x 10(-7) M after epithelial removal, P > 0.05). 2. Ketamine shifted to the right the concentration-response curves for histamine and carbachol in both intact and denuded tracheae. 3. Indomethacin did not alter the relaxant effect of ketamine on the tracheae contracted by either histamine (the concentration that inhibits 50% [IC50] of ketamine = 1.5 +/- 0.01 x 10(-3) M in control strips and 1.3 +/- 0.04 x 10(-3) M in strips pretreated with indomethacin, P > 0.05) or carbachol (the IC50 of ketamine was 2.5 +/- 0.02 x 10(-4) M in control strips and 2.4 +/- 0.01 x 10(-4) M in strips pretreated with indomethacin, P > 0.05). 4. L-NAME did not influence the relaxant effect of ketamine on tracheae contracted by either histamine (the IC50 of ketamine = 1.6 +/- 0.05 x 10(-3) M in control strips and 1.6 +/- 0.05 x 10(-3) M in strips pretreated with L-NAME, P > 0.05) or carbachol (the IC50 of ketamine = 2.6 +/- 0.04 x 10(-4) M in control strips and 2.3 +/- 0.01 x 10(-4) M in trips pretreated with L-NAME, P > 0.05). These results indicate that neither the mechanical removal of the tracheal epithelium nor the blockade of the release of potent mediators from tracheal epithelial cells influence the relaxant effect of ketamine on guinea pig tracheal strips contracted by histamine or carbachol. We conclude that ketamine relaxes the airway smooth muscle by an epithelium-independent mechanism.

Airway Resistance↗
PubMed1991

Bronchodilation by halothane is not modulated by airway epithelium.

Halothane relaxes airway smooth muscles. To test the hypothesis that this relaxation is modulated by airway epithelium, we studied the effects of halothane on isolated second- and third-order canine bronchial rings and second-order canine bronchial segments. Paired rings or segments were examined, with the epithelium removed from one ring or segment of each pair. The bronchial rings were suspended in organ chambers and contracted with 10(-8)-10(-3) M acetylcholine (ACh), 10(-8)-10(-5) M 5-hydroxytryptamine (5HT), or 0.5-16 Hz electrical field stimulation (EFS, 15 V, 0.5-ms pulse duration). The tissue was contracted in the absence of halothane and during exposure to 1 and 2 MAC halothane. The bronchial segments were perfused intraluminally with physiologic salt solution (PSS) and contracted with 10(-6) M carbachol added to the tissue-bath PSS. One or 2 MAC halothane was then added to the perfusate. In the absence of halothane, epithelium removal increased the sensitivity of the bronchial rings to ACh and 5HT but not to EFS. Addition of 1 or 2 MAC halothane to the bathing fluid of the rings with or without epithelium decreased the sensitivity of the rings to ACh and 5HT. One MAC halothane decreased the sensitivity of the rings with and without epithelium to EFS. The decrease in sensitivity caused by halothane was not significantly different in rings with or without epithelium for any method of stimulation. In the bronchial segments, relaxations evoked by 1 or 2 MAC were not different in segments with or without epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1991

Expression of heat shock protein in the atrophic corneal epithelium of the Royal College of Surgeons dystrophic rat.

We report atrophic changes in the corneal epithelium of Royal College of Surgeons (RCS) dystrophic rats. The thickness of the corneal epithelium of 180-day-old RCS dystrophic rats was significantly decreased compared to that of 26-day-old RCS dystrophic and age-matched Sprague-Dawley (SD) rats. Immunostaining for (Na+ + K+) ATPase in the corneal epithelium of 180-day-old RCS dystrophic rats was dramatically reduced when compared to that of 26-day-old RCS dystrophic and age-matched SD rats. In contrast, heat shock protein immunostaining in the corneal epithelium was dense in all of the basal cells, wing cells, and superficial cells of 180-day-old RCS dystrophic rats but was minimally observed in some of the basal cells and in fewer wing and superficial cells of the corneal epithelium of 26-day-old RCS dystrophic and age-matched SD rats. We speculate that toxic products from the degenerating rod outer segments in the course of retinal dystrophy may affect the corneal epithelium, resulting in its atrophy. It is also possible that heat shock proteins appear in the atrophic corneal epithelium due to its degenerative condition.

Animals↗
PubMed1999

Immunohistochemical and ultrastructural analysis of dysplastic epithelium of human ocular surface: basement membrane and intermediate filament.

PURPOSE: The dysplastic corneal epithelium is characterized by the abnormal proliferation of epithelial cells. The phenotypes of these cells have not been elucidated. We investigated whether such epithelium expresses the phenotypes of corneal or conjunctival epithelial cells. METHODS: The corneas and conjunctivae from four normal subjects and from one patient with epithelial dysplasia of the central cornea were immunostained for IV and VII collagens and for cytokeratins. Monoclonal antibodies against collagen IV reacted to the [alpha1(IV)]2alpha2(IV) or alpha5(IV) molecule. Anti-cytokeratin antibodies were used to define epithelial cell types. The ultrastructure of the basement membrane (BM) of each specimen also was examined. RESULTS: Type VII collagen immunoreactivity was detected in all the specimens of epithelial BM. The anti-collagen IV [alpha1(IV)]2alpha2(IV) antibody labeled the conjunctival BMs, not the BMs of the corneal epithelia, of each subject. The normal corneal epithelial BM, not the BM of the conjunctival or dysplastic corneal epithelium, was immunolabeled with anti-alpha5(IV) antibody. The pattern of cytokeratin expression in the corneal epithelial dysplasia resembled that seen in the normal conjunctivae. Small breaks in the BM of dysplastic corneal epithelium were ultrastructurally revealed. The number of hemidesmosomes in the dysplastic corneal epithelium was decreased as compared with that in the normal BM. CONCLUSION: The composition of collagen types within the BM and the cellular phenotype of the dysplastic epithelium in the cornea resembled those of conjunctival epithelium, not of the cornea.

Adult↗
PubMed1996

Characterization of an antigen shared by human thymic epithelium and human T cell leukemia virus p19 Gag protein.

The molecular basis for cross-reactive antibody binding to human T cell leukemia virus type I (HTLV-I) p19 core protein and human thymic epithelium has been defined with two monoclonal antibodies (mAbs), 12/1-2 and 13B12, raised to HTLV-I p19. The mAb 12/1-2 has previously been shown to react with HTLV-I p19, HTLV-II p22, and antigens of normal human thymic epithelium, placenta, and foreskin, whereas mAb 13B12 binds only to the carboxyl terminus of HTLV-I p19. In the present study, mAb 12/1-2 bound to a subset of Triton X-100-insoluble intermediate filaments in human thymic epithelium also recognized by antikeratin antibodies AE1 and AE3. The mAb 12/1-2 also reacted in Western blot assays with proteins of 54, 46, and 40 kDa present in extracts of human thymic epithelium and with hexameric peptides containing overlapping sequences of HTLV-I p19 with the amino acids IPP (amino acids 117-119). In contrast, the HTLV-I-specific mAb 13B12 did not bind to human thymic epithelium and reacted with a single hexameric peptide containing the carboxy-terminal HTLV-I p19 sequence IPPPYV (amino acids 117-122). Binding of mAb 12/1-2 to thymic epithelium could be inhibited by adsorption with peptide SP-79 containing a C-terminal sequence (amino acids 112-125) of p19. The crossreactive IPP site is within a region of p19 that has been previously shown to be highly immunogenic in HTLV-I-infected individuals and that is also encoded by genes or mRNA of human cytokeratin 17, keratin 4, epidermal cytokeratin 2, and 50-kDa type I epidermal keratin. Thus, our studies define the sequence of a cross-reactive antigen on HTLV-I p19 that is also associated with keratin intermediate filaments from human thymic epithelium and other normal human tissues and that could serve as a focus of an autoimmune response during HTLV-I infection.

Amino Acid Sequence↗
PubMed2006

Adaptation of homeostatic ocular surface epithelium to chronic treatment with the opioid antagonist naltrexone.

PURPOSE: To determine how ocular surface epithelium adjusts to an increase in cell replication after treatment with the opioid antagonist naltrexone (NTX). METHODS: Adult male rats were given twice daily injections of 30 mg/kg NTX or vehicle for 7 days. Outcomes of NTX administration included DNA synthesis (monitored with BrdU), mitosis (assayed using colchicine), number of cell layers and cell diameter, apoptosis and necrosis, and packing density for the peripheral corneal epithelium, limbus, and conjunctiva. Also, transit time from basal to surface epithelial layers in the peripheral cornea was assessed with [H]thymidine as a marker. RESULTS: DNA synthesis and mitosis in the basal layer of the peripheral corneal epithelium of NTX-treated rats were increased 69% and 85%, respectively, from control levels; no changes in either parameter were recorded in the limbal or conjunctival epithelium (stem cell region). Epithelial thicknesses in the NTX group were increased by 8% to 38% from control subjects, without more cell layers. Packing density in NTX-treated rats was increased from control values by 26% in the basal layer of the limbus and by 12% to 28% in the suprabasal layers of the corneal epithelium, limbus, and conjunctiva. Epithelial cell diameters from corneas of NTX-exposed rats were subnormal in the basal and suprabasal cells of the limbus and conjunctiva. Apoptosis and necrosis were negligible in the epithelium of NTX-treated and control rats. Transit times of peripheral corneal epithelial cells of animals in the NTX group were shortened by 63% from control levels. CONCLUSIONS: These data show that a 1-week treatment with NTX does not induce proliferative pathology or toxicity in ocular surface epithelium, has a minimal effect on stem cell proliferation, and accelerates normal homeostatic processes. Topical application of NTX for stimulation of corneal epithelial wound healing results in no adverse sequelae, thereby supporting the therapeutic role for this drug in the treatment of ocular surface abnormalities.

Animals↗