Department of Neuroscience
Laboratory of Eye Histochemistry and Pharmacology
Research in the Laboratory of Eye Histochemistry and Pharmacology is focused on the metabolic profile of the anterior eye segment and alter-ations evoked by various diseases or ocular injuries, such as the irradiation of the eye with UV rays and thermal or chemical burns. These severe disorders may result in corneal epithelial limbal stem cell deficiency leading to corneal conjunctivalization (ingrowth of the conjunctival epithelium) and permanent loss of vision. Recently, attempts at corneal regeneration have been started in an animal model (rabbit eye) using mesenchymal stem cell and/or corneal epithelial limbal stem cell transplantation with the aim of vision rehabilitation. In corneal healing processes, attention is devoted to conditions leading to the development of extensive intracorneal or intraocular inflammation. To affect these processes and achieve positive healing, various drugs are employed, particularly specific inhibitors of destructive proteases and scavengers of toxic oxygen products.
Great effort has been devoted to the possibilities of protecting the eye against the damaging effect of UVB rays, known to induce the generation of reactive oxygen species, using UV filters (in cooperation with Laboratoires Thea, Clermont-Ferrand, France).
For evaluating the local toxicity of various drugs, a special method has been developed using the rabbit cornea, and a patent application based on this approach has been submitted (PV 2009–190).
Differences between UVB and UVA rays in terms of corneal light absorption have been distinguished. The same doses of UVB or UVA rays were compared (1. 01 J/cm2 and also UVA at a two-fold larger dose, 2. 02 J/cm2). The results showed that UVB rays are strongly absorbed by the cornea, whereas UVA rays are absorbed by the cornea only in small amounts (Čejka et al., 2007, 2008).
Spectrophotometry results of the of the corneal center, expressed either as the spectrum of transmittance T = T (λ) (A) or absorbance A = A (λ) (B). The spectral curves are means from measurements of 14 normal corneas, 7 irradiated with UVA rays (1. 1 J/cm2, once a day for 5 days), 6 irradiated with a double dose of UVA (2. 2 J/cm2, once a day for 5 days), and 7 irradiated with UVB (1. 1 J/cm2, once a day for 5 days). Note that for wavelengths shorter than about 300 nm, the spectra show the instrumental stray light error rather than the corneal optical properties. The corneas repeatedly irradiated with UVB rays (daily dose of 1. 01 J/cm2 for five days) absorb more light throughout the whole measurable spectral range than do normal corneas. In contrast, no significant differences between normal corneas and corneas irradiated with UVA rays (daily dose of 1. 01 J/cm2 or a double dose, for five days) were found (tested at 320, 380, and 550 nm by one-way ANOVA with Dunnett´s post-test).
Our recent findings show that in some diseases of the ocular surface (particularly of an autoimmune character), oxidative injuries of the ocular surface appear in parallel with clinically observed slit lamp findings. The majority of injuries is evoked by the elevated expression of pro-inflammatory cytokines (Fig. 1), which induce the increased expression as well as activity of enzymatic systems that generate reactive oxidative and nitrosative species. In contrast, enzymatic scavengers of toxic oxygen products are decreased (Čejková et al., Histol Histopathol. 22,997–1003, 2007; Čejková et al., Nitric Oxide 17, 10–7, 2007; Čejková et al., Histol Histopathol 23,1477–83, 2008, Čejková et al., Histol Histopathol 2009, in press).
Immunohistochemical staining of pro-inflammatory cytokines (IL 1-β, IL-6, IL-8, THF-α) in the human conjunctival epithelium of autoimmune dry eye disease (Sjögren´s syndrome, SS). Scale bar: 10 μM. The severity of pro-inflammatory cytokine expression parallels the severity of the symptoms of dryness and the slit-lamp findings. Normal conjunctival cytology samples revealed no or very weak cytokine staining (mature interleukin-1beta (IL 1-β), Fig. 1 a; interleukin 6 (IL-6), Fig. 1 d; interleukin 8 (IL-8), Fig. 1 g; tumor necrosis factor alpha (TNF-α), Fig. 1 j). Only nuclei were stained with haematoxylin. However, all cytokines studied were already expressed in the conjunctival epithelium of dry eye (SS) grade 2, moderate symptoms of dryness with reversible slit-lamp findings (IL 1-β, Fig. 1 b; IL-6, Fig. 1 e; IL-8, Fig. 1 h; TNF-α Fig. 1 k), and their expression increased in the conjunctival epithelium of dry eye (SS) grade 3, severe symptoms of dryness with irreversible slit lamp findings (IL 1-β Fig. 1 c; IL-6, Fig. 1 f; IL-8, Fig. 1 i; TNF-α, Fig. 1 l). Arrows point to cytokine expression.
Current grant support
GA CR, 304/06/1379, Anterior eye segment hypoxia and posthypoxic injury. The role of oxidative stress. Attempts at the development of effective therapies, 2006–2008.
Ministry of Health, NR/8828–3, New methods for the improvement of diagnostic as well as therapeutic purposes of the human eye with dry eye syndrome, 2006–2008.
GA of the Charles University, 47/2006, Light absorption in ocular tissues and fluids with special attention to the cornea, 2006–2008.
Laboratoires Thea, Clermont-Ferrand, France, 0801000013 and CAC08FRO0001123, 2008–2010.
Selected recent publications
1. Čejková J, Vejražka M, Pláteník J, Štípek S. (2004) Age-related changes in superoxide dismutase, glutathione peroxidase, catalase and xanthine oxidoreductase/xanthine oxidase activities in the rabbit cornea. Exp Gerontol 39: 1537–1543.
2. Tessem MB, Bathen TF, Čejková J, Midelfart A. (2005) Effect of UV-A and UV-B irradiation on the metabolic profile of aqueous humor in rabbits analyzed by 1H NMR spectroscopy. Invest Ophthalmol Vis Sci 46: 776–781.
3. Fris M, Tessem MB, Čejková J, Midelfart A. (2006) The effect of single and repeated UVB radiation on rabbit cornea. Graefes Arch Clin Exp Ophthalmol 244: 1680–1687.
4. Čejka Č, Pláteník J, Guryca V, Širc J, Michálek J, Brůnová B, Čejková J. (2007) Light absorption properties of the rabbit cornea repeatedly irradiated with UVB rays. Photochem Photobiol 83: 652–657.
5. Čejková J, Ardan T, Šimonová Z, Čejka Č, Malec J, Dotřelová D, Brůnová B. (2008) Decreased expression of antioxidant enzymes in the conjunctival epithelium of dry eye (Sjögren´s syndrome) and its possible contribution to the development of ocular surface oxidative injuries. Histol Histopathol 23: 1477–1483.
6. Čejka Č, Pláteník, J, Buchal R, Guryca V, Širc J, Vejražka M, Crkovská J, Ardan T, Michálek J, Brůnová B, Čejková J. (2009) Effect of two different UVA doses on the rabbit cornea and lens. Photochem Photobiol 85: 794–800.
7. Čejková J, Ardan T, Čejka Č, Malec J, Jirsová K, Filipec M, Růžičková E, Dotřelová D, Brůnová B. (2009) Ocular surface injuries in autoimmune dry eye. The severity of microscopical disturbances goes parallel with the severity of symptoms of dryness. Histol Histopathol 24: 1357-1365.
