Tamer Demir

Th1 polarization of the immune response in uveitis in Behçet's disease

BACKGROUND It has been reported that abnormalities in the balance of T-helper cells type 1/2 (Th1/Th2) may account for the pathophysiology of human autoimmune diseases. The purpose of this study was to define the role of the Th1/Th2 balance in the pathogenesis of uveitis in Behçets disease (BD). METHODS From February 2003 to August 2005, we studied 31 patients with active BD. Of these patients, 21 (12 female, 9 male; mean age 35.5 [SD 10] years) presented with acute uveitis, and 10 (7 female, 3 male; mean age 34 [SD 11] years) presented with inflammatory arthritis but no prior uveitis attack. The control group consisted of 10 (7 female, 3 male; mean age 34.7 [SD 8] years) age-matched, healthy individuals. CD4+ CD26+ and CD4+ CD30+ cell surface expression of the peripheral blood CD4+ T lymphocytes was evaluated by analytic flow cytometry in order to determine percentages of Th1 and Th2 lymphocyte subsets. RESULTS The mean percentage of CD4+ CD26+ and CD4+ CD30+ cells was 26.27 (SD 6.18) % and 2.56 (SD 0.82) %, 17.42 (SD 5.90) % and 2.86 (SD 0.72) %, and 14.99 (SD 3.96) % and 3.11 (SD 1.25) % in BD with active uveitis, BD with inflammatory arthritis but no prior uveitis attack, and control groups, respectively. T-helper 1 (Th1) cell percentage was significantly higher in the BD with active uveitis group than the BD with arthritis and no prior uveitis attack group (p = 0.001). With respect to the percentage of CD30+ Th2 cells, there was no statistical difference between the 2 BD groups (p = 0.529) or among the 3 groups (p = 0.375). INTERPRETATION Th1 lymphocyte dominance in peripheral circulating blood may play a role in the pathogenesis of BD uveitis.

Levels of circulating homocysteine, vitamin B6, vitamin B12, and folate in different types of open-angle glaucoma

Objective: To compare the levels of plasma homocysteine (Hcy), vitamin B6 (vit-B6), serum vitamin B12 (vit-B12), and folate in healthy individuals and in patients with normal tension glaucoma (NTG), pseudoexfoliative glaucoma (PXG), or primary open-angle glaucoma (POAG). Study design: A prospective controlled trial. Participants and methods: Forty healthy subjects, 48 patients with NTG, 38 patients with PXG, and 34 patients with POAG were included in the study. Those who used vitamin supplements or medications affecting Hcy and vitamin levels were excluded from the study. The levels of Hcy and vit-B6 were measured by High Performance Liquid Chromatography (HPLC). The levels of serum vit-B12 and folic acid were measured by competitive chemiluminescent enzyme immunoassay (CEI). One-way analysis if variance (ANOVA), analysis of covariance (ANCOVA), and the Tukey honestly significant difference test were used for statistical analysis. Results: The mean Hcy level of the PXG group was 15.46 ± 9.27 μmol/L which was significantly higher (P = 0.03) than that of the control group. There were no statistical differences in serum vit-B12 and folate levels among control subjects and NTG, PXG and POAG groups (P > 0.05). It was found that the mean plasma vit-B6 level was significantly higher in subjects with NTG (P = 0.03) and POAG (P = 0.025) versus controls. Mean vit-B6 levels in NTG and POAG were 30.50 ± 11.29 μg/L and 30 ± 12.15 μg/L, respectively. Conclusions: The plasma level of Hcy was found to be increased only in PXG patients and the plasma levels of vit-B6 were found to increase in the NTG and POAG sample groups. Using homocysteine and vit-B6 levels as the determinants of hyperhomocysteinemia still needs further research.

The Protective Effect of Alpha-Lipoic Acid against Oxidative Damage in Rabbit Conjunctiva and Cornea Exposed to Ultraviolet Radiation

Purpose: The purpose of this study was to determine the protective effect of α-lipoic acid against oxidative damage in rabbit conjunctiva and cornea exposed to ultraviolet radiation. Methods: 20 rabbits weighing 2,500– 3,000 g were used, and we divided them into 4 groups with 5 randomly selected rabbits. The rabbits were exposed to 2 J/cm2/h of ultraviolet A radiation (UVA) in the range of 320–405 nm for 12 h per day within 90 days. The control group did not undergo any procedure, the UVA group was only exposed to UVA radiation. The PUVA group was treated with 8-methoxypsoralen and UVA. The α-lipoic acid group was administered 8-methoxypsoralen + UVA + α-lipoic acid. At the end of 90 days, the rabbits were killed by decapitation, and the eyes were enucleated. Both eyes of each rabbit were used for biochemical evaluation. Conjunctival and corneal free malondialdehyde (MDA), glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) levels were compared among the groups. Results: Conjunctival free MDA levels were lower in the α-lipoic acid group compared with the UVA and PUVA groups (p < 0.05, p < 0.001, respectively). Both conjunctival SOD levels (p < 0.05, p < 0.01, respectively) and conjunctival GSH-PX levels (p < 0.01, p < 0.001, respectively) were higher in the α-lipoic acid group compared with other groups. Corneal free MDA levels were lower in the α-lipoic acid group compared with the UVA and PUVA groups (p < 0.01, p < 0.001, respectively). Both corneal SOD levels (p < 0.01, p < 0.01, respectively) and corneal GSH-PX levels (p < 0.01, p < 0.01, respectively) were higher in the α-lipoic acid group compared with the other groups. Conclusion: α-Lipoic acid which is considered as potent antioxidant protects the eye from the damaging effect of ultraviolet exposure.

Effects of Amniotic Membrane Transplantation and Mitomycin C on Wound Healing in Experimental Glaucoma Surgery

Purpose: To evaluate the effects of mitomycin C and amniotic membrane transplantation on the modulation of wound healing after glaucoma filtration surgery. Methods: Trabeculectomy was performed in 3 groups of 10 rabbit eyes each. Sponges soaked in mitomycin C were applied to the first group, and amniotic membranes were transplanted around the scleral flap in the second group; the third group was the control. The arithmetic means of fibroblast and macrophage numbers per square centimetre were calculated. Results: The mean numbers of fibroblasts and macrophages were decreased significantly in the mitomycin C group, compared with the controls (p < 0.0001). Cell counts in the amniotic membrane group were also lower than the ones in the control group for fibroblasts and macrophages (p < 0.0001, p < 0.01, respectively). The difference between the two treatment groups was statistically significant for fibroblasts (p < 0.0001), but not significant for macrophages (p > 0.05). Conclusion: In spite of the fact that amniotic membrane transplantation is less effective than mitomycin C for depressing wound healing after trabeculectomy, it might be a safer alternative in selected cases when considering severe adverse effects of antimetabolites.

L-Carnitine in Experimental Retinal Ischemia-Reperfusion Injury

The effect of L-carnitine on retinal ischemia-reperfusion injury was evaluated in guinea pigs. 90 min of pressure-induced retinal ischemia followed by 24 h of reperfusion was established in both eyes of 2 groups of animals receiving either L-carnitine (100 mg/kg repeated in 5 doses) or saline intraperitoneally. After enucleation of all the eyes, including those of a control group, malonyldialdehyde (MDA) levels and the thickness of the retinal tissue were measured in 3 groups. The mean MDA value and the tissue thickness of the L-carnitine-treated group were statistically insignificant versus the control group (p > 0.05 and p > 0.05, respectively). However, these values were significantly different in the group receiving saline versus the control group and that receiving L-carnitine (p < 0.001, p < 0.001 and p < 0.001, p < 0.001 respectively). L-Carnitine might be an alternative drug for ischemia-reperfusion injury of the retina.

The Impact of Tacrolimus on Vascular Endothelial Growth Factor in Experimental Corneal Neovascularization

Purpose: To investigate the impact of tacrolimus on vascular endothelial growth factor (VEGF) in experimental corneal neovascularization (NV) immunohistochemically. Material and Methods: Five groups of seven Wistar albino rats were formed. A silver nitrate cauterization technique was used to induce corneal NV in the study groups, excluding Group 1 (Control Group). Rats in group 1 did not receive any treatment. Rats in group 2 (sham 1) were administered 1 ml of saline intraperitoneally once a day and those in group 3 (sham 2) received one drop of saline four times a day. Rats in group 4 were administered 0.3 mg/kg tacrolimus intraperitoneally once a day. For group 5, 0.3 mg/ml tacrolimus was installed four times a day. Digital photography for each cornea was performed and the percentage area of the NV on the total corneal surface was calculated. The intensity of VEGF immunostaining in the epithelial, the stromal, and endothelial layers was performed in a semi quantitative fashion. Results: The mean percentages of the neovascularized areas of intraperitoneally and topically tacrolimus-treated groups were lesser than those of the sham groups (p = 0.002, p = 0.038, respectively). The mean intensity of the epithelial VEGF immunostaining of the intraperitoneally tacrolimus-treated group was less than that of its sham group (p = 0.002), while the mean intensity of the stromal VEGF staining of the topically tacrolimus-treated group was lesser than that of its sham group (p = 0.042). The intensities of the endothelial VEGF immunostaining of the intraperitoneally and topically tacrolimus-treated groups were less than those of the sham groups (p = 0.038, p = 0.032). Conclusion: Systemic and topical administration of tacrolimus may be beneficial in the prevention of corneal NV because of its effect on VEGF.

Phthriasis palpebrarum mimicking lid eczema and blepharitis.

Phthiriasis palpebrarum (PP) is a rare eyelid infestation caused by phthirus pubis. We report a case of PP mimicking lid eczema and blepharitis. A 68-year-old woman had moderate itching in both eyes. Her initial diagnosis was considered to be lid eczema or blepharitis because of findings similar to exfoliative lesions and color changes in eyelids and to excretions over eyelashes. Careful observation revealed many lice and translucent nits, protuberances and hyperpigmentary changes, and the buried lice in both eyelids. No hyperemia or secretion was observed on the lids and in the conjunctiva in both eyes. The patient was treated with pilocarpine hydrochloride 4% drops. At the end of the first week, no louse or nit was present. Although it was known that PP is a rare cause of blepharoconjunctivitis, it might observe as an isolated infestation of the eyelids and this condition can easily be misdiagnosed as lid eczema and blepharitis.

The impact of tacrolimus on growth factors in experimental proliferative vitreoretinopathy.

Purpose To investigate the effect of intravitreal tacrolimus on an animal model of proliferative vitreoretinopathy (PVR) and on growth factors implicated in its pathogenesis. Methods Twenty-one guinea pigs were randomly assigned to one of three groups of seven animals each: no-PVR/saline group (no PVR/intravitreal saline-injected group), PVR/saline group (dispase-induced PVR group, treated with control injections of intravitreal saline), and PVR/tacrolimus group (treatment group, dispase-induced PVR group treated with intravitreal tacrolimus injections). At the end of the experiment, eyes were enucleated and the identification of the stages of PVR was carried out. While a halves of the enucleated globes were evaluated histopathologically for PVR formation, the retinas of the other halves of globes were used for the preparation of retinal homogenates. The transforming growth factor-&bgr;, platelet-derived growth factor, and fibroblast growth factor levels in homogenized retina tissues were measured by the enzyme-linked immunosorbent assay method. Results When assessing the average PVR stages in terms of severe PVR rates, the PVR/tacrolimus group had significantly improved when compared with the PVR/saline group. The PVR/tacrolimus group demonstrated significantly decreased levels of transforming growth factor-&bgr;, platelet-derived growth factor, and fibroblast growth factor when compared with the PVR/saline group and also demonstrated significant improvement in epiretinal membrane formation and retinal fold in the presence of histopathologic levels. The difference in degradation of photoreceptor cells between the PVR/tacrolimus and the PVR/saline groups was not statistically significant. Conclusion This study suggests that intravitreal tacrolimus application may suppress PVR development and that tacrolimus may merit investigation for the prophylaxis of PVR.

The effect of infliximab, cyclosporine A and recombinant IL-10 on vitreous cytokine levels in experimental autoimmune uveitis.

BACKGROUND To identify the effect of infliximab, cyclosporine A and recombinant IL-10 in experimental autoimmune uveitis. MATERIALS AND METHODS Sixty male rats were assigned to five groups of 12 each. All the groups (except the control group) were administered 30 microg retinal-S antigen intraperitoneally. On the 14th day, after confirmation of uveitis with histopathological study, daily cyclosporine A injection was given in cyclosporine A treatment group and physiological serum in the uveitis-induced placebo treatment and control groups. In the infliximab treatment group, infliximab was administered on the 14th, 15th, 17th, 19th and 21st days. In the recombinant IL-10 treatment group, three doses of recombinant IL-10 were given four hours and a half hours before and eight hours after retinal-S antigen administration. On the 21st day of the study, all rats were sacrificed and vitreous cytokine levels (IL-1, IL-6, IL-8 and TNF-alpha) were studied with ELISA. RESULTS In the treatment groups, cytokine levels (IL-1, IL-6 and TNF-alpha) were significantly lower than the uveitis-induced placebo treatment group. Compared with the control group, there was no significant difference with respect to TNF-alpha and IL-8 in the infliximab treatment group; IL-8 in the cyclosporine A treatment group; IL-6 and IL-8 in the recombinant IL-10 treatment group. The drugs used did not significantly differ in respect to their effects on vitreous IL-6, IL-8 and TNF-alpha levels. CONCLUSION Cyclosporine A, infliximab and recombinant IL-10 reduce the vitreous cytokines levels. Among these drugs, recombinant IL-10, which is still in its experimental phase, might be considered as a new therapeutic agent.

Protective effects of pentoxifylline in retinal ischemia/reperfusion injury.

We studied the effect of pentoxifylline on retinal lipid peroxidation and histopathologic changes due to ischemia/reperfusion (I/R). A total of 15 pigmented male guinea pigs were divided into 3 equal groups as control, sham and treatment groups. After application of high intraocular pressure for 90 min for the induction of retinal ischemia, 24-hour reperfusion was established in the sham and treatment groups. In the treatment and sham groups, either 45 mg/kg of pentoxifylline or saline was given 3 times at 8-hour intervals. Biochemical assay and histopathologic evaluation were performed on one randomly selected eye of each animal which was enucleated at the end of the reperfusion period, and retinal malondialdehyde (MDA) levels and thickness of the retinal tissue were determined for each group. The mean MDA level of the sham group was significantly higher versus the control and treatment groups (p < 0.001). When compared with the control group, the mean MDA level of the treatment group was slightly higher, but the difference was not statistically significant (p > 0.05). In comparison with the control group there was a significant increase in the thickness of the retina in the sham group (p < 0.0001), and no significant difference was found in the retinal thickness of the treatment group (p > 0.05). Pentoxifylline might have a preventive effect on the I/R injury of the retina.