Higher aqueous levels of matrix metalloproteinases indicated visual impairment in patients with retina vein occlusion after anti-VEGF therapy.

PURPOSE: To investigate the levels of matrix metalloproteinases (MMPs) in aqueous humour of patients with retinal vein occlusion (RVO) and the relationship between intraocular MMP levels and retinal lesion and visual prognosis. MATERIALS AND METHODS: 52 RVO patients, including 23 with central retinal vein occlusion (CRVO) and 29 with branch retinal vein occlusion (BRVO) and 20 participants with senile cataract were enrolled in this study. Retinal lesions were examined by fundus colour photography, fluorescein fundus angiography and optical coherence tomographic angiography. Sixty microliters of aqueous humour were collected during intravitreal anti-Vascular Endothelial Growth Factor (VEGF) injection or cataract surgery. The aqueous levels of MMP-1, MMP-2, MMP-7, MMP-9 and MMP-10 were measured using the Luminex xMAP multiplex assay. The relationship between MMP levels and clinical presentations was analysed by Pearson correlation test. RESULTS: The aqueous humour levels of MMP-1, MMP-2, MMP-7 and MMP-9, but not MMP10 in RVO patients were significantly higher than those in people with cataract after adjusting for age. Further analysis of RVO subgroups showed that the aqueous humour level of MMP2 in CRVO was significantly higher than that in BRVO. The aqueous humour levels of MMP-1 and MMP-2 were positively correlated with superficial capillary plexus vessel density (SVD), whereas the aqueous humour levels of MMP-1 and MMP-7 were negatively correlated with visual improvement following treatment. No correlation between aqueous humour levels of MMP and disease duration and central retinal thickness was observed. CONCLUSIONS: RVO eyes had significantly higher intraocular levels of MMP-1, MMP-2, MMP-7 and MMP-9 than cataract eyes and the level of MMP2 appears to be related to the area of occlusion. Intraocular levels of MMP may positively affect SVD and negatively impact visual function in RVO.

Changes in the Systemic Expression of Sirtuin-1 and Oxidative Stress after Intravitreal Anti-Vascular Endothelial Growth Factor in Patients with Retinal Vein Occlusion.

OBJECTIVES: Retinal vein occlusions (RVO) are associated with systemic risk factors. However, the ocular occlusive events might also influence a patient's systemic condition. This study tried to investigate serum biomarkers associated with oxidative stress, before and after intravitreal anti-vascular endothelial growth factor (aVEGF) therapy in patients with RVOs. METHODS: Newly-onset RVO patients were categorized into two groups: comorbid with macular edema requiring aVEGF therapy (treatment group) and no edema (observation group). Age and sex-matched patients (who received cataract surgery) were included as the control group. Intravitreal ranibizumab with a pro-re-nata regimen were administered. Serum samples were collected prior to treatment, at 6 and 12 months after therapy/observation and were collected once before controls who received cataract surgery. mRNA expression of sirtuin-1, its downstream genes, anti-oxidative biomarkers, and proinflammatory cytokines were measured. RESULTS: There were 32, 26, and 34 patients enrolled in the treatment, observation, and control groups, respectively. The expressions of sirtuin-1 and its downstream genes were significantly lower in patients with RVO compared with the control group. Sirtuin-1 gene expression increased after 1 year of aVEGF therapy in the treatment group but remained unchanged in the observation group. Biomarkers of oxidative stress and proinflammatory cytokines were reduced after 1 year of aVEGF therapy. These biomarkers remained with no changes in the observation group. CONCLUSIONS: Our study showed that the systemic oxidative stress increased in RVO patients. The aVEGF therapy could alter the gene expression of anti-oxidative proteins and reduce systemic oxidative stress in these patients.

INCREASED SYSTEMIC HEPARANASE IN RETINAL VEIN OCCLUSION IS ASSOCIATED WITH ACTIVATION OF INFLAMMATION AND THROMBOPHILIA.

PURPOSE: To investigate the levels of systemic heparanase, inflammatory markers, and coagulation factor activities in patients with retinal vein occlusion (RVO). METHODS: This prospective study included 18 patients with central RVO, 22 patients with branch RVO, and 40 patients with age-related cataract as the control group. Serum heparanase protein levels and activities were measured by ELISA and a heparan degrading enzyme assay kit, respectively. Serum levels of MMP-2, MMP-9, TLR-2, and TLR-4 were measured by ELISA kits. The activities of coagulation factors (V, VII, VIII, and IX) were determined with an autoanalyzer. The Mann-Whitney U test was used to compare the above parameters between patients with RVO and control subjects. The relationship between two of the above parameters was analyzed by Spearman's correlation. RESULTS: Patients with RVO had higher levels of systemic heparanase protein, heparanase activities, coagulation factors' (V, VIII, and IX) activities, MMP-2, MMP-9, TLR-2, and TLR-4 compared with the control group. Systemic heparanase levels were correlated with serum levels of MMP-2, MMP-9, TLR-2, TLR-4, and activities of coagulation factors VIII and IX. CONCLUSION: Increase of systemic heparanase in RVO is associated with activation of systemic inflammation and blood hypercoagulability.

Thrombophilic risk factors for retinal vein occlusion.

The aim is to study risk factors for retinal vein occlusion (RVO), such as thrombophilic and cardiovascular risk factors (CRF). A retrospective consecutive case series of 60 patients with RVO was made, tested for CRF, hyperhomocysteinemia, lupic anticoagulant, antiphospholipid antibody and 5 gene variants: factor V (FV) Leiden (G1691A), factor II (PT G20210A), 5,1-methylenetetra-hydrofolate reductase (MTHFR; 677 C > T and 1298 A > C), plasminogen activator inhibitor 1 (PAI-1; 4 G/5 G). More than 1 CRF were present in 36 patients (60%), which had a significantly higher mean age at diagnosis (66.7 ± 12.9 versus 59.5 ± 13.7 with ≤1 CRF, [t(57) = -2.05, p = 0.045, d = 0.54). Patients with thermolabile MTHFR forms with decreased enzyme activity (T677T or C677T/A1298C) had a significant lower mean age [57.6 ± 15.1; t (58) = 3.32; p = 0.002; d = 0.846] than patients with normal MTHFR enzyme activity (68.5 ± 10.2). Regarding CRF and thermolabile forms of MTHFR, the mean age at diagnosis could be significantly predicted [F(2,56) = 7.18; p = 0.002] by the equation: 64.8 - 10.3 × (thermolabile MTHFR) - 5.31 × ( ≤ 1CRF). Screening of MTHFR polymorphisms may be useful in younger RVO patients, particularly when multiple CRF are absent.

Serum heparanase concentration and heparanase activity in patients with retinal vein occlusion.

PURPOSE: To investigate the serum heparanase concentration and heparanase activity of the patients with central retinal vein occlusion (CRVO) or branch retinal vein occlusion (BRVO). METHODS: This prospective study included 23 CRVO patients, 13 BRVO patients and 28 control subjects. Serum heparanase concentration was measured by ELISA. Serum heparanase activity was determined using a heparan degrading enzyme assay kit (Mountain View, CA, USA). Multivariate logistic regression was used to adjust for the possible confounding factors when comparing the difference in serum heparanase concentration and activity between patients with RVO and control subjects. RESULTS: Patients with CRVO (3.963 ± 0.816 U/l) or BRVO (3.371 ± 1.522 U/l) had significantly higher levels of heparanase protein compared to controls (1.055 ± 0.902 U/l). This significance remained after adjusting for aforementioned confounding factors (CRVO versus control, p = 0.000, 95%CI: 2.450-4.488; BRVO versus control, p = 0.006, 95%CI: 0.776-4.050). Patients with CRVO (0.3587 ± 0.1498 U/ml) or BRVO (0.3616 ± 0.0570 U/ml) had significantly higher levels of heparanase activity compared to controls (0.1449 ± 0.0952 U/ml). The significance was maintained after adjusting for the aforementioned confounding factors (CRVO versus control, p = 0.012, 95%CI: 0.036-0.275; BRVO versus control, p = 0.000, 95%CI: 0.150-0.395). There was no significant difference in serum heparanase protein levels and activities between CRVO and BRVO groups before and after confounding factor adjustment. CONCLUSION: Our study provides the first direct clinical link between systemic heparanase protein levels and heparanase activity with RVO, suggesting a critical role for heparanase in the pathophysiology of RVO.

Association of methylenetetrahydrofolate reductase (A1298C and C677T) polymorphisms with retinal vein occlusion in Tunisian patients.

The role of two polymorphisms C677T and A1298C of the methylenetetrahydrofolate reductase (MTHFR) gene in the etiology of retinal vein occlusion (RVO) has not been adequately clarified. The aim of this study was to examine the prevalence of these polymorphisms among RVO Tunisian patients with and without systemic risk factors. Seventy-two patients with retinal vein occlusion (RVO) were studied. The control group included140 people matched for age, sex, and risk factors. Participants in the study were genotyped for the MTHFR C677T and A1298C polymorphisms. The genotyping was performed by PCR-RFLP. No significant differences were found in the frequencies of the three genotypes (AA, AC, CC) of the MTHFR A1298C polymorphism between RVO patients and healthy controls. However, the prevalence of the group of mutated genotypes (AC+CC) of the missense variant MTHFR A1298C was significantly different between patients and controls (16.67% vs. 6.42%, p=.01). Additionally, the frequency of the CT genotype as well as the group of combined mutated genotypes (CT+TT) for the C677T variant was significantly higher among RVO patients compared with controls (p<10(-3), p<10(-3)). This suggests an association between this polymorphism and RVO. Large study populations would be required to understand more completely the contribution of these markers in the risk of RVO.

Protective effect of paraoxonase 1 gene variant L55M in retinal vein occlusion.

PURPOSE: To determine if the paraoxonase 1 L55M and paraoxonase 1 Q192R gene polymorphisms have an effect on the risk of having a retinal vein occlusion (RVO). METHODS: This case-control prospective study included 120 patients with RVO and 84 control subjects. All subjects were screened for age, gender, hypertension, diabetes, body mass index, fibrinogen, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, total cholesterol, and very low-density lipoprotein. Subjects were also questioned about their smoking habits. Genomic DNA was extracted from peripheral leukocytes from EDTA anticoagulated blood. Genotyping of the paraoxonase 1 L55M and paraoxonase 1 Q192R polymorphisms was performed using real-time PCR. RESULTS: The frequency of the paraoxonase 1 (PON1) 55 LL genotype was significantly lower in patients with RVO than in the control subjects (28% versus 55%; p = 0.005). Logistic regression analyses were also conducted. After adjusting for gender, diabetes, hypertension, plasma fibrinogen levels, and high-density lipoprotein cholesterol, the lower LL genotype was found to be an independent predictor of RVO (ß = 1.755; odds ratio = 5.783; p < 0.001; 95% confidence interval = 2.579-12.967). CONCLUSIONS: Subjects with a lower frequency PON1 55 LL genotype had a higher risk of RVO. These results indicate that paraoxonase gene polymorphisms may be a possible risk factor for RVO. We suggest that the LL genotype may have a protective role in the pathogenesis of RVO in the Turkish population.

Predictive value of the vitamin K epoxide reductase complex subunit 1 G-1639A and C1173T single nucleotide polymorphisms in retinal vein occlusion.

BACKGROUND: To determine if vitamin K epoxide reductase complex subunit 1 gene polymorphisms have an effect on the risk of having a retinal vein occlusion. DESIGN: Case-control study. PARTICIPANTS: The study population consisted of 68 patients who were newly diagnosed with retinal vein occlusion and 66 sex-matched controls. METHODS: Genomic DNA was extracted from peripheral leukocytes from ethylenediamine tetra-acetic acid-anticoagulated blood. Genotyping of the vitamin K epoxide reductase complex subunit 1 G-1639A (rs 9923231) and C1173T (rs 9934438) single nucleotide polymorphisms was performed using real-time polymerase chain reaction and commercially available kits. MAIN OUTCOME MEASURES: A full ophthalmological evaluation was performed in each subject, and all subjects were screened for hypertension, hypercholesterolaemia and diabetes. The genotypes of the vitamin K epoxide reductase complex subunit 1 single nucleotide polymorphisms were determined. RESULTS: The vitamin K epoxide reductase complex subunit 1 GG and CC genotypes were more frequent (41% vs. 21%; P = 0.021), and the combined GA/AA and CT/CC genotypes were less frequent in patients with retinal vein occlusion than in control subjects. After adjusting for hypertension, age, plasma fibrinogen levels and prevalence of diabetes and hypercholesterolaemia, the GG and CC genotypes were found to be an independent predictor of retinal vein occlusion (B = 2.28; odds ratio = 9.79; P = 0.003; 95% confidence interval: 2.22-43.24). CONCLUSION: It was found that subjects with the vitamin K epoxide reductase complex subunit 1 GG and CC genotypes had a higher risk of retinal vein occlusion.

Activated protein C rescues the retina from ischemia-induced cell death.

PURPOSE: Ischemia causes severe and persistent visual loss in many eye diseases, including central retinal vein occlusion (CRVO) and diabetic retinopathy. Activated protein C (APC) has been demonstrated to reduce the cell death associated with ischemia in the brain and kidney. This study was performed to examine the ability of APC to rescue hypoxia-induced retinal cell death in vitro and in vivo. METHODS: Retinal pigment epithelium (RPE) and photoreceptor cells were placed in either a normoxic or a hypoxic chamber. Immediately before they were subjected to ischemia, the cultures were treated with APC (3-240 µg/mL). Incubation was followed by an MTT assay to determine the number of viable cells. The activity of caspase-3, -8, and -9 in RPE cells was also analyzed. Various concentrations of APC were intravitreally injected in a rat CRVO model, followed by TUNEL staining to detect the in vivo effects of APC. RESULTS: Lower concentrations of APC (0.3-30 µg/mL) showed a cell-protective effect against hypoxia in vitro, whereas higher concentrations (≥120 µg/mL) demonstrated cytotoxicity in both RPE and photoreceptor cells. Caspase-3, -8, and -9 were activated when the cells were exposed to hypoxia, but this activation was significantly inhibited by APC. Experimental CRVO-induced retinal cell apoptosis was reduced dramatically by intravitreal injection of APC. CONCLUSIONS: APC can reduce ischemia-induced cytotoxicity both in vitro and in vivo via blocking the activation of caspase-3, -8, and -9. APC may be a promising candidate for protecting the retina from ischemia.

Serum PON1 arylesterase activity in relation to hyperhomocysteinaemia and oxidative stress in young adult central retinal venous occlusion patients.

AIM: To estimate the arylesterase activity of serum paraoxonase-1 (PON1-ARE), which is reported to have an antioxidant and antiatherogenic potential and to correlate with plasma homocysteine (Hcys) and plasma TBARS in young adult central retinal venous occlusion (CRVO) patients. METHODS: A case-control prospective study carried out in 10 CRVO patients (mean age 27+/-5 years; 7 males, 3 females) and 20 healthy controls (mean age 29+/-5 years; 15 males, 5 females). RESULTS: The CRVO patients showed a significantly lowered serum PON1-ARE activity (P=0.009) along with a significant increase in the levels of plasma Hcys (P=0.018) when compared to the control subjects. There was a negative correlation between serum PON1-ARE and plasma Hcys levels (P=0.058) as well as between PON1-ARE and plasma TBARS levels (P=0.001) in the CRVO patients. CONCLUSION: This is the first report of lowered serum PON1-ARE level as a risk factor for CRVO (OR= 1.108, CI=0.914, 1.314; P=0.296), which is found to correlate with oxidative stress.

Assessment of the role of thrombin activatable fibrinolysis inhibitor in retinal vein occlusion.

PURPOSE: To determine whether elevated levels of thrombin activatable fibrinolysis inhibitor (TAFI) may contribute to thrombotic risk for patients with retinal vein occlusion (RVO) and to investigate the possible correlations between TAFI activity level and other conventional risk factors. METHODS: Ninety patients with RVO (cases), except those receiving medication affecting the study parameters, those undergoing a surgical procedure within the last week, and those with kidney and/or liver failure, were enrolled in the study. The control group included similar patients matched for age and sex. After written informed consent was obtained, parameters including TAFI activity levels, conventional risk factors, results of routine hematological examination, and factor V Leiden and prothrombin G20210A mutations were evaluated by analysis of blood samples obtained after an 8-hour fast. RESULTS: Although TAFI activity levels were slightly elevated in cases (190.5 +/- 43.8) compared with controls (183.9 +/- 41.8), the difference was not statistically significant (P = 0.36). According to evaluation of TAFI activity in subgroups (>200%, 150-200%, and 0-150%), 36.7% with central RVO, 40.0% with branch RVO, and 30% of controls were found to have TAFI activity of >200% (P = 0.83). TAFI activity levels did not correlate with age, sex, demographics, clinical status, and hematological variables. Finally, in stepwise regression analysis, TAFIa (carboxypeptidase U) activity was not found to be an important risk factor for RVO. CONCLUSION: On the basis of these data, TAFI activity was not found to be a new risk factor for either type of RVO. However, further larger studies may better identify the exact role of TAFI in the pathogenesis of RVO.

Hyperhomocysteinemia and the methylenetetrahydrofolate reductase 677C-T mutation in patients under 50 years of age affected by central retinal vein occlusion.

PURPOSE: To investigate the correlation between increased homocysteine plasma levels and the homozygosity for the 677C-T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in patients aged under 50 years affected by central retinal vein occlusion (CRVO). DESIGN: Prospective, case-control study. PARTICIPANTS AND CONTROLS: Participants included 31 consecutive patients under 50 years and diagnosed with CRVO. Two controls per case were selected. The first control group (group I) included 31 individuals matched for age, gender, laboratory tests, and the main risk factors for atherosclerosis. The second control group (group II) consisted of 31 volunteers matched only for age and gender. METHODS: Fasting (>10 hours) blood samples were obtained from patients and controls. Blood samples were obtained from patients within 1 week after the onset of the vaso-occlusive event. Molecular genetic analysis for the 677C-T mutation in the MTHFR gene was performed in patients and controls. A plasma homocysteine reading of >12 micromol/l was considered an increase. MAIN OUTCOME MEASURES: The total homocysteine plasma level (determined by the high-performance liquid chromatography method with fluorescence detection) and molecular genetic analysis for the 677C-T mutation in the MTHFR gene in patients and controls. RESULTS: Mean ages were 44.5 years in the group comprising the patients and 44.3 and 44.2 years, respectively, in groups I and II. Mean homocysteine plasma levels were 10.60 micromol/l in patients and 10.39 and 9.34 micromol/l, respectively, in groups I and II. There was no statistically significant difference between mean homocysteine plasma levels in patients and group I controls. In fact, the mean homocysteine plasma level was lower in group II than in patients, and the difference was statistically significant. Homozygosity for the 677C-T mutation in the MTHFR gene was found in 4 patients (12.9%), 5 controls in group I (16.1%), and 4 controls in group II (12.9%). CONCLUSION: The results of the present investigation support the hypothesis that the homocysteine plasma level is not to be considered a primary and independent risk factor for CRVO, but is more likely a marker of atherosclerosis and the consequence of other well-established risk factors. Moreover, the importance of the study design is brought out, because the results we obtained differ on the basis of the considered control group. This feature may in part explain the contradictory results reported in the literature.

Hyperhomocyst(e)inemia, but not methylenetetrahydrofolate reductase C677T mutation, as a risk factor in branch retinal vein occlusion.

OBJECTIVE: To determine whether hyperhomocyst(e)inemia and methylenetetrahydrofolate reductase (MTHFR) C677T mutation are associated with branch retinal vein occlusion (BRVO). DESIGN: Retrospective, case-control study. PARTICIPANTS: The study cohort consisted of 84 consecutive patients with branch retinal vein occlusion and 84 controls, matched for age and gender. MAIN OUTCOME MEASURES: Fasting plasma homocyst(e)ine, folate, and vitamin B(12) levels, MTHFR C677T genotypes. RESULTS: Mean plasma homocyst(e)ine levels were significantly higher in patients than in controls (11.4 +/- 4.3 micromol/l vs. 9.9 +/- 2.8 micromol/l; P = 0.002). An increase of plasma homocyst(e)ine level by 1 micromol/l was associated with an odds ratio of 1.19 (95% confidence interval 1.06-1.34; P = 0.004). Mean plasma folate levels were significantly lower in patients than in the control group (4.5 +/- 2.1 ng/ml vs. 5.6 +/- 2.1 ng/ml; P = 0.007). The prevalence of the homozygous genotype of the MTHFR C677T mutation did not differ significantly between patients and controls. CONCLUSIONS: Our results suggest that hyperhomocyst(e)inemia, but not homozygosity for the MTHFR C677T mutation, is associated with BRVO. Increased plasma homocyst(e)ine levels in our study are not the result of an increased prevalence of the homozygous genotype of MTHFR C677T mutation.

Hyperhomocyst(e)inemia and MTHFR C677T genotypes in patients with central retinal vein occlusion.

BACKGROUND: Elevated plasma homocyst(e)ine is a major risk factor for venous thrombosis and cardiovascular disease. Homozygosity for the MTHFR C677T mutation and low plasma folate levels increase plasma homocyst(e)ine concentrations. The aim of this retrospective case-control study was to investigate a possible association between hyperhomocyst(e)inemia and central retinal vein occlusion. METHODS: Our study included 78 consecutive patients with central retinal vein occlusion and 78 control subjects, matched for age and sex. High-performance liquid chromatography (HPLC) with fluorescence detection was used to determine fasting plasma homocyst(e)ine concentrations. Plasma folate and vitamin B12 levels were determined by immunological assays. Genotyping for the MTHFR C677T mutation was performed by polymerase chain reaction (PCR). RESULTS: Hyperhomocyst(e)inemia was defined by the 95th percentile of plasma homocyst(e)ine concentrations in the control group (=14.83 micromol/l). Thus 16 patients with central retinal vein occlusion were diagnosed as hyperhomocyst(e)inemic, compared with three control subjects ( P=0.001). The odds ratio of hyperhomocyst(e)inemia for central retinal vein occlusion was 5.29 (95% CI 1.33-21.13). Mean plasma folate levels were significantly lower in patients than in controls (3.94+/-1.94 ng/ml vs. 5.69+/-2.09 ng/ml; P<0.001). Distribution of MTHFR C677T genotypes did not significantly differ between the two groups. CONCLUSIONS: Our study suggests that hyperhomocyst(e)inemia, but not the MTHFR C677T mutation, is associated with central retinal vein occlusion.

Hyperhomocysteinemia and the MTHFR C677T mutation in central retinal vein occlusion.

BACKGROUND: Hyperhomocysteinemia is a factor that predisposes to thrombosis, and the C677T mutation in methylene-tetrahydrofolate reductase (MTHFR) is known to give increased plasma homocysteine. We wanted to investigate if these factors were overrepresented in a group of patients with central retinal vein occlusion. METHODS: 116 patients with a history of central retinal vein occlusion were examined for the presence of hyperhomocysteinemia and the MTHFR C677T mutation. RESULTS: Compared to the control groups, there was no significant increase, neither in plasma homocysteine nor in the frequency of the MTHFR C677T mutation in the patients. Even when we looked selectively at the young patients, age less than 50 years, no difference could be detected. CONCLUSION: It seems that neither hyperhomocysteinemia nor the MTHFR C677T mutation is an important risk factor for the aetiology of central retinal vein occlusion.

Retinal vein occlusion associated with methylenetetrahydrofolate reductase mutation.

OBJECTIVE: To report on the occurrence of methylenetetrahydrofolate reductase (MTHFR) deficiency in patients with retinal vein occlusion (RVO). DESIGN: Prospective case series PARTICIPANTS: Fifty-nine consecutive patients with newly diagnosed RVO seen at the Retina Unit in the Tel Aviv Medical Center during 1997. METHODS/TESTING: Interviews and multiple blood analyses were done. Data were compared to the reported incidence of MTHFR deficiency in the Israeli population at large. RESULTS: Twenty-six patients (44.1%) were heterozygotes and 11 (18.6%) were homozygotes for 677C-T mutation in MTHFR. The MTHFR 677C-T homozygosity was documented as being present in 10.4% of healthy individuals in the Israeli population. The difference in homozygosity was found to be statistically significant (P = 0.038). CONCLUSIONS: Retinal vein occlusion may be associated with a mutation in MTHFR.

Alterations in protein tyrosine kinase pathways following retinal vein occlusion in the rat.

PURPOSE: To determine whether an experimental retinal vein occlusion in the rat activates protein tyrosine kinase pathways and increases angiogenic growth factors in the retina. METHODS: Retinal vein occlusion (RVO) was induced in the rat retina with argon laser photocoagulation. Retinas were collected at 2 days, 1, 2, and 4 weeks after RVO and divided into halves: one half represented an area within the distribution of the occluded vein [RVO(IN)] and the other half represented an area outside the distribution of the occluded vein [RVO(OUT)]. RVO(IN) and (OUT) were examined by western blot analysis of tyrosine-phosphorylated proteins, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and 3 signal proteins in the tyrosine kinase pathways: phospholipase Cgamma (PLCgamma), phosphatidylinositol 3-kinase (PI3K), and mitogen-activated protein kinase (MAPK). RESULTS: RVO caused a severe capillary nonperfusion in RVO(IN). Overall tyrosine-phosphorylated proteins were increased after RVO, especially in RVO(IN) at 2 days and 1 week. VEGF and bFGF were markedly increased in RVO(IN) at 2 days and 1 week. Tyrosine-phosphorylated PLCgamma, PI3K, and MAPK were also increased in RVO(IN) at these time points. CONCLUSIONS: RVO caused an increase in overall protein tyrosine phosphorylation in the rat retina. This increase was associated with an increase in angiogenic growth factors (VEGF and bFGF). These results suggest that protein tyrosine kinase pathways are activated during retinal ischemia and may play a role in mitogenesis of vascular endothelial cells and other responses in the retina after RVO.

Molecular variant of the human paraoxonase/arylesterase gene is associated with central retinal vein occlusion in the Japanese population.

Central retinal vein occlusion (CRVO) is a complex trait caused by a number of local and systemic factors. Among the latter, atherosclerosis has been attributed a major pathogenic role. Recently, the paraoxonase/arylesterase (PONA) enzyme has been implicated in the pathogenesis of atherosclerosis. There is a 10- to 40-fold variability in the activity of this enzyme among individuals. This variability is due to the presence of an A/G polymorphism in the coding region of the gene. The A and G alleles code for glutamine (A genotype) and arginine (B genotype), respectively. We determined the PONA genotypes and alleles in 42 patients with CRVO and in 45 control subjects of the Japanese population. The distribution of AA, AB and BB genotypes were 9.6, 45.2 and 45.2%, respectively, in the patients and 26.7, 53.3 and 20.0% in the control subjects, respectively (p < 0.05). The A allele frequency was 0.32 in patients and 0.53 in controls (p < 0.01). In conclusion, molecular variants of the PONA gene are involved in the predisposition to CRVO. Further studies are needed to characterize the molecular mechanism by which the PONA enzyme is involved in atherosclerosis.

Bilateral retinal vein occlusion associated with 5,10-methylenetetrahydrofolate reductase mutation.

PURPOSE: To report on the occurrence of 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency, known to cause mild to moderate hyperhomocystinemia and increased risk of vascular occlusive disease, in a young patient with bilateral central retinal vein occlusion. METHODS: A 25-year-old man was initially examined with central retinal vein occlusion in the right eye, followed 4 months later by a central retinal vein occlusion in the left eye. Studies for risk factors predisposing to thrombosis were performed. RESULTS: Hematologic studies failed to detect any pathology. However, the patient was found to be homozygous for 677C-T mutation in MTHFR enzyme. CONCLUSION: Central retinal vein occlusion may be associated with a mutation in MTHFR.