Differences in gene expression in lymphocytes of patients with high-tension, PEX, and normal-tension glaucoma and in healthy subjects.

PURPOSE: Purpose Differences in the gene expression of leukocytes between patients with normal-tension glaucoma (NTG) and controls have been described. This study was performed in order to detect the differences in gene expression in peripheral lymphocytes in patients with primary open-angle glaucoma (POAG), patients with pseudoexfoliation glaucoma (PEX), and patients with NTG, and in healthy subjects. METHODS: Ten patients with POAG, 11 patients with PEX, 10 patients with NTG, and 42 sex- and age-matched healthy persons were recruited. All study subjects were Caucasian. Twenty-two preselected genes were chosen and their expression in blood lymphocytes was quantified by real-time PCR. First, a univariate comparison among all groups was performed using the nonparametric Friedman test. Second, an L1 penalized logistic regression was performed. RESULTS: Using the Friedman test to compare the 4 groups, 9 genes showed a different expression (p<0.05). Comparing the controls vs patients with POAG, 8 genes were differently expressed (p<0.05). Comparing patients with PEX vs controls, 9 genes were significantly different (p≤0.05). The statistical analysis of patients with NTG vs controls showed a difference in gene expression of 7 genes (p≤0.05). All these genes were upregulated in the glaucoma groups compared with the controls. The genes RhoGDI and RAR showed the most significant statistical difference in the L1-penalized logistic regression. The genes overexpressed in POAG/PEX differed from the ones in NTG. CONCLUSIONS: In this masked study among the preselected 22 genes, several genes are overexpressed in the blood lymphocytes of Caucasian patients with glaucoma compared with the controls. The genes upregulated in POAG/PEX differed from the ones in NTG.

Plasma citrate levels as a potential biomarker for glaucoma.

PURPOSE: To determine the possibility of plasma citrate as a biomarker in patients with glaucoma. METHODS: Twenty-one consecutive Caucasian patients with glaucoma and 21 sex- and age-matched controls were investigated. Plasma citrate, plasma creatinine, urine citrate, and urine creatinine were analyzed by ion chromatography. Mean (±standard deviation) concentrations and the calculated fractional citrate excretions were compared using the Mann-Whitney test. Sensitivity and specificity to detect glaucoma using plasma citrate levels were calculated. RESULTS: The mean plasma citrate (104.8±23.2 vs. 128.2±31.1 µmol/L; P=0.01) concentrations were significantly lower among the patients with glaucoma, whereas the mean urine citrate concentrations (1.7±0.9 vs. 2.8±1.9 µmol/L; P=0.07) were slightly lower. Mean plasma and mean urine creatinine concentrations showed no significant differences (plasma creatinine: 63.0±16.7 vs. 63.4±15.5 µmol/L; P=0.72; urine creatinine: 9.6±5.1 vs. 11.5±8.4 µmol/L; P=0.67). The calculated fractional citrate excretions were also not different with 12.1% versus 13.6% (P=0.37). Setting the cut-off limit at 110 µmol/L, the plasma citrate level evaluation would have a sensitivity of 66.7% and a specificity of 71.4% to detect glaucoma. CONCLUSION: In this masked study, plasma citrate levels were significantly decreased in Caucasian patients with glaucoma giving the possibility to use them eventually as a biomarker. The kidney function was normal in both groups, leaving the etiology of this hypocitraemia yet unexplained.

Retinal vein occlusions: The potential impact of a dysregulation of the retinal veins.

A retinal vein occlusion (RVO) is a sight threatening disease. It can be divided into central vein occlusion and branch retinal vein occlusion. The pathogenesis of the condition remains to be solved. Mechanical compression of the vessel wall or thrombotic occlusion of the vessel lumen, sometimes combined with rheological disorders, are often assumed pathomechanisms. Accordingly, the therapy relies either on mechanical decompression, lyses of thrombi or improvement of rheology. A number of observations however, such as the relationship of RVO to atherosclerotic risk factors, spontaneous reversibility particularly in young patients, rest flow observed in angiography, occlusion despite anticoagulation or thrombocytopenia and finally the positive effect of anti-VEGF therapy are not explained by the present pathogenetic concept. As a new concept we propose a local venous constriction induced by vasoconstrictive molecules diffusing from neighbouring diseased arteries and/or from other neighbouring (hypoxic) tissues. Recognizing these postulated conditions might lead to an earlier identification of impending vein occlusions as well as to a treatment more tailored to the risk factor constellation of the particular patient.

Identification of lymphatics in the ciliary body of the human eye: a novel "uveolymphatic" outflow pathway.

Impaired aqueous humor flow from the eye may lead to elevated intraocular pressure and glaucoma. Drainage of aqueous fluid from the eye occurs through established routes that include conventional outflow via the trabecular meshwork, and an unconventional or uveoscleral outflow pathway involving the ciliary body. Based on the assumption that the eye lacks a lymphatic circulation, the possible role of lymphatics in the less well defined uveoscleral pathway has been largely ignored. Advances in lymphatic research have identified specific lymphatic markers such as podoplanin, a transmembrane mucin-type glycoprotein, and lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1). Lymphatic channels were identified in the human ciliary body using immunofluorescence with D2-40 antibody for podoplanin, and LYVE-1 antibody. In keeping with the criteria for lymphatic vessels in conjunctiva used as positive control, D2-40 and LYVE-1-positive lymphatic channels in the ciliary body had a distinct lumen, were negative for blood vessel endothelial cell marker CD34, and were surrounded by either discontinuous or no collagen IV-positive basement membrane. Cryo-immunogold electron microscopy confirmed the presence D2-40-immunoreactivity in lymphatic endothelium in the human ciliary body. Fluorescent nanospheres injected into the anterior chamber of the sheep eye were detected in LYVE-1-positive channels of the ciliary body 15, 30, and 45 min following injection. Four hours following intracameral injection, Iodine-125 radio-labeled human serum albumin injected into the sheep eye (n = 5) was drained preferentially into cervical, retropharyngeal, submandibular and preauricular lymph nodes in the head and neck region compared to reference popliteal lymph nodes (P < 0.05). These findings collectively indicate the presence of distinct lymphatic channels in the human ciliary body, and that fluid and solutes flow at least partially through this system. The discovery of a uveolymphatic pathway in the eye is novel and highly relevant to studies of glaucoma and other eye diseases.