Effects of N-acetylcysteine on matrix metalloproteinase-9 secretion and cell migration of human corneal epithelial cells.

BACKGROUND: Matrix metalloproteinase-9 (MMP-9) secreted by corneal epithelial cells has a role in the remodelling of extracellular matrix and migration of epithelial cells. Elevated levels of MMP-9 activity in the ocular surface may be involved in the pathogenesis of corneal diseases. N-acetylcysteine (NAC) has been used to treat corneal diseases, including recurrent epithelial erosions. In this study, its effects on the MMP-9 secretion and human corneal epithelial (HCE) cell migration were evaluated in vitro. METHODS: Confluent HCE cell cultures were treated with 0-20 mM NAC, and tested for MMP-9 secretion and epithelial cell migration by gelatin zymography and scratch wound assay, respectively. Comparisons between different treatment groups were made using analysis of variance, followed by multiple pairwise comparisons. RESULTS: Twenty mM NAC inhibited the secretion of MMP-9 significantly. Cell migration, assessed after 24 h of wounding, showed a highly significant dose-dependent inhibitory effect. CONCLUSIONS: This study shows that NAC reduces MMP-9 production by HCE cells and inhibits cell migration in vitro. This information helps to elucidate the mechanisms by which NAC may be beneficial therapeutically and suggests that NAC may be useful for managing corneal erosions and related conditions.

Evolving concepts on the pathogenic mechanisms of aniridia related keratopathy.

Heterozygosity for PAX6 deficiency (PAX6+/-) results in aniridia. Corneal changes in aniridia-related keratopathy (ARK) include corneal vascular pannus formation, conjunctival invasion of the corneal surface, corneal epithelial erosions and epithelial abnormalities, which eventually result in corneal opacity and contribute to visual loss. Corneal changes in aniridia have been attributed to congenital deficiency of corneal limbal stem cells. The aim of this paper is to review the potential mechanisms that may underlie the pathogenesis of aniridia related keratopathy. Current evidence, based on clinical observations and an animal model of aniridia suggest that the proliferative potential of the corneal limbal stem cells may not primarily be impaired. The corneal changes in aniridia may be related to an abnormality within the limbal stem cell niche. The mechanisms underlying progressive corneal pathology in aniridia appear multi-factorial and include: (1) abnormal corneal healing responses secondary to anomalous extracellular matrix metabolism; (2) abnormal corneal epithelial differentiation leading to fragility of epithelial cells; (3) reduction in cell adhesion molecules in the PAX6 heterozygous state, rendering the cells susceptible to natural shearing forces; and (4) conjunctival and corneal changes leading to the presence of cells derived from conjunctiva on the corneal surface.

Immunolocalisation of leukaemia inhibitory factor in the cornea.

AIM: Leukaemia inhibitory factor (LIF) is a pleotrophic cytokine expressed in a variety of cell types, and have shown to regulate stem cell proliferation, vascular genesis, inflammation, and immunity in various locations. Expression of LIF and its role in the cornea have not been studied previously. In this study, we examined the expression of LIF in the cornea. MATERIALS AND METHOD: Immunohistochemistry was performed using polyclonal LIF antibodies, and Avidin-Biotin ABC complex on cultured human corneal epithelium corneal fibroblasts and wild-type murine corneal epithelium. RESULTS: LIF was detected in the cytoplasm of murine corneal epithelium, cultured human corneal epithelium, and fibroblasts. The expression of LIF was mainly cytoplasmic. CONCLUSION: LIF is expressed in the corneal epithelium and fibroblasts. It may have an important role in the maintenance of homeostasis of the corneal epithelium and cornea stroma. Further studies are necessary to elucidate the role of LIF in the cornea.

The effect of tobacco smoking and of betel chewing with tobacco on the buccal mucosa: a cytomorphometric analysis.

The effect of tobacco use on the buccal mucosa has been assessed by cytomorphometry. Cell and nuclear diameters (CD, ND) of exfoliated oral squames were measured in tobacco smokers (S), betel chewers with tobacco (C) and those with a combined habit (S+C). Non-users (NU) served as controls. The mean CD values in S, C, S+C and NU were: 50.8 (+/-0.47), 49.39 (+/-0.48), 49.12 (+/-0.47) and 51.87 (+/-0.76) microm, and the mean ND values were: 8.83 (+/-0.07), 8.61 (+/-0.08), 8.72 (+/-0.10) and 8.33 (-/+ 0.09) microm, respectively. The least significant difference procedure (LSD at P=0.05) showed a significant reduction for CD in C and S+C and an increase for ND in all three habit groups, compared to the controls. This study shows that the use of tobacco influences the cytomorphology of the normal buccal mucosa. Betel chewing with tobacco influences the ND and CD, while smoking influences only the ND.

Diagnosis of oral premalignant and malignant lesions using cytomorphometry.

In this study cytomorphometry has been applied to smears collected from the buccal mucosa. Normal cells and the cells collected from lesions with no dysplasia, dysplasia and squamous. cell carcinoma were differentiated using discriminant analysis based on nuclear and cell diameter values. Cytomorphometrically the dysplastic and malignant cells were well discriminated from the normal cells. A sensitivity of 89%, specificity of 89.7%, positive predictive value of 80% and negative predictive value of 94.4% were obtained when comparing non-dysplastic lesions with dysplastic lesions.

Cytomorphometric analysis of squames obtained from normal oral mucosa and lesions of oral leukoplakia and squamous cell carcinoma.

Cell and nuclear diameters (CD and ND) were measured in squames obtained from normal buccal mucosa and lesions of oral leukoplakia and squamous carcinoma (SCC) also from buccal mucosa. The study groups consisted of Group 1: normal buccal mucosa (n = 40); Group 2: lesions with no epithelial dysplasia (n = 58); Group 3: lesions with epithelial dysplasia (n = 27); and Group 4: SCC lesions (n = 51). The mean CD and ND values were: Group 1: 51.78 (+/- 0.11) and 8.36 (+/- 0.49); Group 2: 45.73 (+/- 0.16) and 8.31 (+/- 0.68); Group 3: 41.32 (+/- 0.13) and 9.04 (+/- 0.46); Group 4: 38.58 (+/- 0.11) and 10.10 (+/- 0.56) microns, respectively. Correlation between the ND and CD was positive for Group 1 (r = 0.78, P < 0.05) and Group 2 (r = 0.33, P < 0.05). There were no significant correlations in Groups 3 and 4. ANOVA showed significant differences (P < 0.05) for CD between all four groups. Except between Groups 1 and 2, the ND was significantly different (P < 0.05) between all groups. The results indicate that ND and CD could possibly be sensitive parameters in the diagnosis of oral premalignant and malignant lesions.

Exfoliative cytology in screening for malignant and premalignant lesions in the buccal mucosa.

OBJECTIVE: To test the efficacy of exfoliative cytology in the detection of oral premalignant and malignant lesions. DESIGN: Cytological diagnosis of lesions of the buccal mucosa assessed using histopathological diagnosis of the same lesions as the gold standard. SUBJECTS: Patients with buccal lesions clinically diagnosed as leukoplakia (n = 91) and squamous cell carcinoma (SCC, n = 59), and healthy subjects (n = 40) in whom buccal mucosa appeared clinically normal. SETTING: Oral and Maxillo-facial Unit, General Hospital, Kandy and Department of Pathology, Faculty of Medicine, University of Peradeniya. RESULTS: A sensitivity of 77%, specificity of 100% and accuracy of 92% were obtained for leukoplakia. SCC gave a sensitivity of 94%, specificity of 100% and an accuracy of 95%. CONCLUSIONS: Oral exfoliative cytology is a useful method for detecting oral premalignant and malignant lesions. Anucleated squames in a smear is non-diagnostic.