Keratoconjunctivitis sicca modifies epithelial stem cell proliferation kinetics in conjunctiva.
ABSTRACT The objective of this study was to examine the epithelial stem cell proliferation kinetics in a rat model with keratoconjunctivitis sicca (KCS).
Wistar rats received a daily injection of 5-bromo-2-deoxyuridine (BrdU) at a dose of 5 mg/100 g of body weight for 2 weeks. Dry eye was induced in 2 groups of rats by subcutaneous injection of scopolamine and placed in a desiccating environment: The first group received dry eye treatment at the beginning of BrdU labeling for 2 weeks; the second group received dry eye treatment after BrdU labeling for 4 weeks. Rats receiving no dry eye treatment were used as controls. Aqueous tear production, tear clearance, and corneal barrier function of dry eye rats were compared with those of control rats. Ocular epithelial morphology and goblet cell density were also evaluated in histologic sections. One month after BrdU injection, epithelial stem cell proliferation kinetics was assessed by BrdU labeling.
Significant decreases in tear fluid secretion and tear clearance were noted in rats 5 days after dry eye treatment, with significantly increased corneal carboxy fluorescein uptake. Changes in ocular surface epithelial morphology and significantly reduced density of conjunctival goblet cells were found in dry eye groups. The number of conjunctival BrdU label-retaining cells in the rats with dry eye was significantly decreased compared with control rats (P < 0.01 for both groups). Furthermore, BrdU labeling in the before dry eye induction group showed more label-retaining basal cells in the conjunctiva than labeling in the dry eye state group (P < 0.01).
Experimentally induced KCS in rats causes significant modification of epithelial stem cell proliferation kinetics in conjunctiva. The modification of epithelial stem cell proliferation kinetics in conjunctiva may play a crucial role in the development of KCS and may be a therapeutic target for this condition.
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ABSTRACT: To correlate tear fluorescein clearance with interleukin-1alpha (IL-1alpha) concentration and gelatinase B (matrix metalloproteinase [MMP]-9) activity in the tear fluid of patients with ocular rosacea and normal control subjects. Gelatinase activity was evaluated by gelatin zymography in tear fluid obtained from 13 patients with ocular rosacea (including 1 patient with recurrent epithelial erosion, 2 with recurrent peripheral corneal infiltrates and vascularization, and 2 patients with epithelial basement membrane dystrophy) and 13 normal subjects with normal aqueous tear production and no irritation symptoms. Tear fluorescein clearance was evaluated by measuring fluorescence in tear fluid collected from the inferior meniscus 15 minutes after instillation of 5 microl of 2% Na-fluorescein with a CytoFluor II fluorometer. Pro-MMP-9 and IL-1alpha concentrations in the tear fluid were measured by enzyme-linked immunosorbent assay (ELISA). Compared with normal control subjects, patients with ocular rosacea had a greater delay of tear fluorescein clearance (P < 0.001), a higher tear IL-1alpha concentration (P < 0.001), and a greater pro-gelatinase B (92 kDa) activity (P < 0.001) in their tear fluid. The 84-kDa active form of gelatinase B was observed in 46% of the rosacea tear samples and none of the controls. The zymographic results were confirmed by ELISA that showed a significantly greater concentration of pro-MMP-9 (92 kDa) in the tear fluid of rosacea patients than controls. Delayed tear clearance was correlated with elevated tear IL-1alpha concentration (p=0.67, P < 0.001) and increased tear gelatinase B activity (p=0.84, P < 0.001). Tear IL-1alpha concentration was correlated with tear gelatinase B activity (p=0.58, P < 0.002). Gelatinase B (MMP-9) activity is greater in patients with ocular rosacea than in normal eyes. The majority of this activity is due to 92-kDa proform of this enzyme. This activity is correlated with delayed tear clearance and tear fluid concentration of interleukin-1alpha, a proinflammatory cytokine that has been reported to stimulate gelatinase B production. Elevated gelatinase B activity in ocular rosacea may be involved in the pathogenesis of the irritation symptoms, recurrent epithelial erosions, vascularization, and epithelial basement membrane dystrophy that develops in the corneas of patients with this condition.Investigative Ophthalmology & Visual Science 11/1999; 40(11):2506-12. · 3.44 Impact Factor
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ABSTRACT: The mechanism of corneal wound healing has not been clarified yet. However, evidence has accumulated that various kinds of growth factor such as epidermal growth factor (EGF), fibroblast growth factor (FGF), transforming growth factor (TGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF) play a key role in corneal wound healing. For example, these growth factors are expressed in the corneal epithelial cells, keratocytes and endothelial cells, and their receptors are expressed in the corneal cells. Furthermore, these growth factors promote the proliferation of corneal cells and induce the migration of corneal cells. In addition to the growth factors, inflammatory cytokines such as interleukin (IL)-1, IL-6 and TNF-alpha are involved in corneal wound healing. These cytokines are expressed in the normal and inflammatory cornea after infections, alkaliburn, etc. where they control the growth of corneal cells and induce the migration of corneal cells. Thus, a number of growth factors and cytokines function in the regulation of corneal cell proliferation and in the maintenance of corneal transparency.Progress in Retinal and Eye Research 01/2000; 19(1):113-29. · 9.44 Impact Factor
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ABSTRACT: We have continued our study of the tear film and ocular surface in our full KCS (keratoconjunctivitis sicca) rabbit model up to 52 weeks post-operatively. Tear film osmolarity remains elevated, conjunctival goblet cell density remains decreased, and the conjunctival epithelium remains abnormal. Corneal epithelial glycogen levels decreased progressively, and at 44 weeks post-operatively rabbits developed abnormal rose Bengal staining of the affected cornea that was shown to be associated with morphologic abnormalities at 52 weeks. Rabbits began rubbing the affected eye after the development of corneal staining. Our full KCS rabbit model demonstrates the features of the human disease.Acta ophthalmologica Scandinavica. Supplement 02/1989; 192:95-101.