The aim of this study was to detect a spectrum of cytokeratins (CK) present in the adult human cornea, limbus and perilimbal conjunctiva. Cryosections from seven corneo-scleral discs were fixed, and indirect immunofluorescent staining was performed using antibodies directed against CK1-CK10 and CK13-CK20. The percentage of positive cells was calculated in the epithelium of the cornea, limbus and perilimbal conjunctiva. Quantitative real time RT-PCR (qRT-PCR) was used to detect CK6 and CK18 expression in the corneal and conjunctival epithelium. The most intense staining present throughout the cornea was observed for CK3, CK5 and CK14; CK19 was found at the corneal periphery only. CK4 and CK10/13 revealed mild to moderate positivity mostly in the superficial layers of the cornea. The suprabasal cell layers of all examined areas showed a strong positivity for CK16. A heterogeneous staining pattern with a centrifugal decrease in the signal was observed for CK8 and CK18. CK5/6, CK14 and CK19 were present in the limbus, where a positive signal for CK3 was observed in the suprabasal and superficial cells only. In contrast to the cornea, CK15 appeared in the basal and suprabasal layers of the limbus. The perilimbal conjunctiva showed strong immunostaining for CK10/13, CK14 and CK19. A moderate signal for CK7 was detected in the superficial layers of the conjunctiva. qRT-PCR confirmed CK6 and CK18 expression in the corneal and conjunctival epithelium. The detailed characterization of the corneal, limbal and perilimbal conjunctival epithelium under normal circumstances may be useful for characterizing the changes occurring under pathological conditions.
- MeSH
- Adult MeSH
- Microscopy, Fluorescence MeSH
- Fluorescent Antibody Technique, Indirect MeSH
- Glyceraldehyde-3-Phosphate Dehydrogenases metabolism MeSH
- Immunohistochemistry MeSH
- Keratins biosynthesis genetics metabolism MeSH
- Conjunctiva metabolism MeSH
- Middle Aged MeSH
- Humans MeSH
- Limbus Corneae metabolism MeSH
- Reverse Transcriptase Polymerase Chain Reaction MeSH
- RNA biosynthesis genetics MeSH
- Cornea metabolism MeSH
- Epithelium, Corneal metabolism MeSH
- Aged MeSH
- Sclera metabolism MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
PURPOSE: To present cytokeratin (CK)7 (OV-TL 12/30 clone) as a newly identified, reliable marker for distinguishing between the conjunctival and corneal surface epithelia, which will contribute to the precise diagnosis of limbal stem cell deficiency (LSCD). METHODS: Corneal and conjunctival epithelial imprints from 12 cadaveric bulbi and from 9 patients with clinically diagnosed LSCD were used for CK7 and CK19 immunocytochemistry. Specimens on nitroacetate cellulose filter papers obtained from the patients were stained with a combination of periodic acid-Schiff (PAS) and Gill's modified Papanicolaou stains, to assess the presence of goblet cells (GCs). RESULTS: CK7 was present in almost all superficial conjunctival epithelial cells from the cadaveric specimens. No immunostaining was observed on the corneal surface. A prominent sharp border of stain was found between the positive conjunctiva and the completely negative epithelium of the central cornea. A more gradual centrifugal decrease in the number of positive cells between the conjunctiva and cornea was observed for CK19. Several CK19-positive cells were detected in the central corneal epithelium. All corneal specimens from affected eyes (unilateral as well as bilateral LSCD patients) revealed strong positivity for CK7, and GCs were present in only 78% of patients. CONCLUSIONS: In cases in which GCs are severely decreased or are absent from the conjunctival surface, the detection of CK7 (OV-TL 12/30 clone) clearly confirms the overgrowth of the conjunctival epithelium over the cornea. Moreover, CK7 is a more reliable marker for distinguishing between the corneal and conjunctival epithelia compared with CK19.
- MeSH
- Biomarkers MeSH
- Adult Stem Cells pathology MeSH
- Adult MeSH
- Keratin-19 immunology metabolism MeSH
- Keratin-7 genetics immunology metabolism MeSH
- Conjunctiva metabolism pathology MeSH
- Middle Aged MeSH
- Humans MeSH
- Limbus Corneae metabolism pathology MeSH
- Cadaver MeSH
- Corneal Diseases metabolism pathology MeSH
- Antibodies immunology MeSH
- Epithelium, Corneal metabolism pathology MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Antibody Specificity MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Posterior polymorphous corneal dystrophy (PPCD) is a rare, bilateral autosomal dominant disorder affecting primarily the corneal endothelium and descemet membrane (DM). The aim of this study was to establish the origin of abnormal endothelium in a patient with PPCD exhibiting cornea graft failure after keratoplasty surgery. A sex-mismatched graft obtained from a patient with PPCD who underwent repeat penetrating keratoplasty and the patient's original cornea were investigated. Combined fluorescent immunohistochemistry for cytokeratin (CK) 19 (a marker of aberrant PPCD endothelium) with fluorescence in situ hybridization (FISH) of the sex chromosomes were used in order to characterize the cells on the posterior graft surface. The pathological endothelium of the failed PPCD cornea revealed strong positivity for CK19 using fluorescent immunohistochemistry. In all the CK19-positive cells, both X and Y chromosomes were simultaneously detected using FISH. The results clearly showed the original cells of the patient (XY), within 3.5 years, almost totally overgrown the posterior corneal surface of the graft (XX). Moreover, an abnormal posterior collagenous layer populated by fibroblast-like cells was observed between DM and the endothelium in the failed graft, but its exact origin could not be established due to the low number of cells. Simultaneous detection of CK19 using fluorescent immunohistochemistry together with the detection of gonosomes using FISH was performed for the first time in the cornea and allowed us to prove that the recurrence of PPCD was caused by pathological abnormal proliferation and migration of recipient cells into donor graft.
- MeSH
- Corneal Dystrophies, Hereditary genetics pathology MeSH
- Descemet Membrane pathology MeSH
- In Situ Hybridization, Fluorescence MeSH
- Keratins metabolism MeSH
- Middle Aged MeSH
- Humans MeSH
- Chromosomes, Human, X MeSH
- Chromosomes, Human, Y MeSH
- Endothelium, Corneal cytology metabolism pathology MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
PURPOSE: The purpose of this study was to investigate the expression of cytokeratin (CK) 8 in the corneoconjunctival epithelium. METHODS: In 17 cadaveric corneoscleral discs and 3 other discs, the presence of CK8 alone or CK8, together with CK3, CK15, vimentin, and integrin α6, was investigated by using indirect immunohistochemistry on radial cryosections. Four corneoscleral discs stored in organ culture were used for the preparation of tangential sections of the limbus and for the isolation of limbal epithelial cells and their subsequent cultivation. CK8 expression was examined by RT-PCR in the corneal, limbal, and conjunctival epithelium. RESULTS: Sixty percent of the cadaveric corneoscleral samples and all samples stored in organ culture revealed positivity for CK8 in the basal epithelial layer of the limbus. Positive basal cells formed a single line or separated clusters. The signal for CK8 became weaker toward the surface of the limbal epithelium. The colocalization of CK8 with vimentin and CK15 in the limbus was also found. CK3 showed only occasional positivity in some of the surface limbal cells. The expression of integrin α6 in the basal membrane was absent or decreased under the CK8-positive clusters. Cell cultures revealed strong positivity for CK8 in approximately 80% of the cultured cells, and CK8 expression in the cornea, limbus, and conjunctiva was determined by RT-PCR. CONCLUSIONS: The study demonstrates the strong expression of CK8 in limbal epithelial basal cells, which is maintained during the differentiation and migration of the limbal cells toward the central corneal epithelium.
- MeSH
- Cell Culture Techniques MeSH
- Adult MeSH
- Epithelial Cells metabolism MeSH
- Gene Expression MeSH
- Microscopy, Fluorescence MeSH
- Fluorescent Antibody Technique, Indirect MeSH
- Integrin alpha6 metabolism MeSH
- Keratin-15 metabolism MeSH
- Keratin-3 metabolism MeSH
- Keratin-8 genetics metabolism MeSH
- Conjunctiva cytology metabolism MeSH
- Middle Aged MeSH
- Humans MeSH
- Limbus Corneae cytology metabolism MeSH
- RNA, Messenger genetics MeSH
- Adolescent MeSH
- Organ Culture Techniques MeSH
- Reverse Transcriptase Polymerase Chain Reaction MeSH
- Epithelium, Corneal cytology metabolism MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Vimentin metabolism MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The goal of our study was to determine whether proteins typical of the human mesothelial cell phenotype, such as mesothelin, HBME-1 (Hector Battifora mesothelial cell-1) protein and calbindin 2, are expressed in the human cornea, especially in endothelial cells. Cryosections and endothelial and epithelial imprints of sixteen human cadaverous corneoscleral discs were used. The presence of proteins was examined using immunohistochemistry and Western blotting, while mRNA levels were determined by qRT-PCR. A strong signal for mesothelin was present in the corneal epithelium, while less intense staining was visible in the endothelium. Similarly, higher and lower mRNA levels were detected using qRT-PCR in the corneal epithelium and endothelium, respectively. HBME-1 antibody strongly stained the corneal endothelium and stromal keratocytes. Marked positivity was present in the corneal stromal extracellular matrix, while no staining was present in the sclera. Calbindin 2 was detected using immunohistochemistry and Western blotting in the corneal epithelium, endothelium and stroma. qRT-PCR confirmed its expression in epithelial and endothelial cells. Three proteins expressed constitutively in mesothelial cells were detected in the human cornea. The possible function of mesothelin in cell-cell contact on the ocular surface is discussed. The presence of HBME-1 protein in the endothelial layer may indicate a still unknown function that could be shared with mesothelial cells of the pleura and peritoneum. The much more pronounced occurrence of calbindin 2 in the corneal epithelium compared to fewer positive endothelial cells explains the higher turnover of epithelial cells compared to the proliferatively inactive endothelium.
- MeSH
- Fluorescent Antibody Technique, Indirect MeSH
- GPI-Linked Proteins MeSH
- Immunoenzyme Techniques MeSH
- Middle Aged MeSH
- Humans MeSH
- Membrane Glycoproteins genetics metabolism MeSH
- RNA, Messenger genetics MeSH
- Biomarkers, Tumor genetics metabolism MeSH
- Eye Proteins metabolism MeSH
- Reverse Transcriptase Polymerase Chain Reaction MeSH
- Endothelium, Corneal metabolism MeSH
- Epithelium, Corneal metabolism MeSH
- S100 Calcium Binding Protein G genetics metabolism MeSH
- Corneal Stroma metabolism MeSH
- Blotting, Western MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Posterior polymorphous corneal dystrophy (PPCD) is a hereditary bilateral disorder affecting Descemet's membrane and the endothelium. The aim of the present study was to determine the spectrum of cytokeratin (CK) expression in cells on the posterior surface of the cornea in PPCD patients. Ten corneal buttons and one specimen of the trabecular meshwork (TM) from PPCD patients who underwent graft or glaucoma surgery were used, as well as six corneal buttons and two TM specimens obtained from healthy donors as controls. Cryosections were fixed and indirect immunofluorescent staining was performed using antibodies directed against a wide spectrum of cytokeratins (CKs). The number of positive cells and the intensity of the staining were assessed using fluorescent microscopy. All 10 PPCD corneal specimens had areas of endothelium displaying typical endothelial morphology as well as areas consisting of layers two to six cells thick with both flat endothelial-like cells and polygonal cells with round nuclei and a large cytoplasm. Both of these morphologically distinct cell types showed strong immunostaining for CK7, CK19, CK8 and CK18, while weaker positive signals were observed for CK1, CK3/12, CK4, CK5/6, CK10, CK10/13, CK14, CK16 and CK17. PPCD endothelium was completely negative for CK2e, CK9, CK15, and CK20. Focal positivity was detected in PPCD TM for CK4, CK7 and CK19. CK8 and CK18 were the only CKs expressed in control endothelium. PPCD and control epithelium displayed similar staining patterns. The distinct positivity for CK3/12, CK4, CK5/6, CK10/13, CK14, CK16 and CK17 was observed in aberrant PPCD endothelium for the first time. We demonstrate that the abnormal endothelium of PPCD patients expresses a mixture of CKs, with CK7 and CK19 predominating. In terms of CK composition, the aberrant PPCD endothelium shares features of both simple and squamous stratified epithelium with a proliferative capacity. The wide spectrum of CK expression is most probably not indicative of the transformation of endothelial cells to a distinct epithelial phenotype, but more likely reflects the modified differentiation of metaplastic epithelium.
- MeSH
- Corneal Dystrophies, Hereditary metabolism pathology MeSH
- Financing, Organized MeSH
- Microscopy, Fluorescence methods MeSH
- Immunohistochemistry methods MeSH
- Keratins, Type I analysis MeSH
- Keratins, Type II analysis MeSH
- Keratins analysis MeSH
- Middle Aged MeSH
- Humans MeSH
- Eye Proteins analysis MeSH
- Endothelium, Corneal abnormalities metabolism pathology MeSH
- Trabecular Meshwork metabolism MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
