Vasospastic individuals demonstrate significant similarity to glaucoma patients as revealed by gene expression profiling in circulating leukocytes

Abstract

Purpose: There is growing evidence that vasospatic individuals could be predisposed to develop glaucoma. Vasospastic deregulation is ensuing in activation of circulating leukocytes. In previous studies using "gene-hunting" strategies, we demonstrated stable alterations in gene expression profiles of circulating leukocytes isolated from glaucoma patients with vascular deregulation when compared to healthy individuals with no history of glaucomatous damage. The goal of this study was to look for possible similarities in gene expression profiles of circulating leukocytes in vasospastic individuals and glaucoma patients.

Methods: Normal-tension (NTG) and high-tension (HTG) glaucoma patients as well as individuals with vascular deregulation (VD) and healthy controls were recruited for the gene expression analysis. The methodology of comparative Expression Array analysis followed by highly sensitive quantitative real-time PCR has been used.

Results: Compared to the control group the expression of 146, 68, and 60 genes was found to be altered in NTG, HTG, and VD groups respectively. Thirty-four genes demonstrated similar expressional alterations in NTG, HTG, and VD groups versus controls, and only 21 genes demonstrated similar expressional alterations in NTG and HTG groups, having no overlap with the VD group.

Conclusions: This result indicates a potential predisposition of vasospastic individuals to glaucomatous optic nerve atrophy. The targeted expression profiles might be further considered for early/predictive glaucoma diagnosis.

Figure 1

Expression Array image. The image of 588 genes (see Atlas^TM Human Cardiovascular Array in Methods) is shown specifically for the group of individuals with vascular deregulation. The double spots marked with black frames show the most stable expressional difference in vascular deregulation (VD), normal-tension (NTG) and high-tension (HTG) glaucoma patients groups versus controls. These double-spots are zoomed for the groups tested (ZOOM), and the names of corresponding genes as well as their positions in Atlas are given.

Figure 2

Comparative real-time PCR. The measurements for the most stable alterations (see the “Expression array” images as given in Figure 1) were performed in glaucoma patients compared to controls. All measurements have been performed by a blind study. The names of the encrypted genes are following: the gene 1=P2Y (purinoceptor 7); the gene 2=ICAM 1 (intercellular adhesion molecule 1); the gene 13=Na⁺/Ca²⁺ EP1 (Na⁺/Ca²⁺ exchange protein 1); the gene 22=MT1-MMP (membrane type 1 matrix metalloproteinase).

Figure 3

Overview of protein expression profiling. The diagram demonstrates the overlap in molecular mechanisms among single pathologies according to the similarities in gene expression patterns in vascular deregulation (VD), normal-tension (NTG) and high-tension (HTG) glaucoma patients groups. Single disorders demonstrate some pathology-characteristic expressions marked by the corresponding symbol, e.g., NTG. Further, there are partial expression overlaps between two of three pathologies symbolized by the corresponding pair, e.g., NTG & HTG. The similarities among all three groups (NTG & HTG & VD) of comparison are considered as the central issue that this study is focused on. Altogether 34 genes that create this overlap are summarized in Table 3, providing the clue to the molecular pathomechanisms that potentially predispose vasospastic individuals to the glaucomatous pathology.