Endothelin-1 levels and biomarkers of oxidative stress in glaucoma patients

Abstract

To investigate the levels of endothelin-1 (ET-1), homocysteine (Hcy), vitamins A, E, B12 and folic acid in plasma of patients with different types of glaucoma: primary open-angle glaucoma (POAG) and normotensive glaucoma (NTG). Patients were classified into 3 groups: group POAG comprised 48 patients, group NTG comprised 15 patients, and control group that comprised 75 healthy subjects. ET-1 levels were measured by ELISA, Vitamins A and E by HPLC, and Vitamin B12, homocysteine, and folic acid levels were determined by chemiluminescent immunoassay. The ET-1 and Hcy levels were significantly higher (p = 0.002) in the POAG group compared to NTG and control group. Vitamin E levels were significantly lower (p = 0.001) in the NTG group compared to POAG and control group. The increase of Hcy and ET-1 in POAG patients is related to vascular endothelial dysfunction. Thus results may play a key role in the development of this disease. Lower levels of Vitamin E in the NTG group suggest that oxidative process plays an early role in the development of this type of glaucoma.

Lack of Association between Serum Vitamin B6, Vitamin B12, and Vitamin D Levels with Different Types of Glaucoma: A Systematic Review and Meta-Analysis

“…Romano et al [26] suggested that vitamin B 12 treatment represents a powerful strategy to accelerate not only re-epithelization, but also corneal re-innervation after mechanical injury. Contradictory results have also been reported for the association between serum vitamin B 12 and glaucoma [6,9,10,11,12]. …”

“…From the 181 studies, 168 were excluded. Finally, 13 studies [6,7,8,9,10,11,12,13,14,19,20,21,22] were included in this meta-analysis. The detailed characteristics of each included study are presented in Table 1.…”

“…Since some studies discussed different types of glaucoma, they could be included in more than one group. Thus, there were nine studies included in the POAG group [6,7,8,10,11,12,13,14,19], four in the NTG group [6,9,10,12], and six in the EXG group [6,11,12,20,21,22]. Moreover, according to the different types of vitamins considered (vitamin B 6 /vitamin B 12 /vitamin D), the following categorizations were identified:

The POAG group: Three studies considered vitamin B 6 (109 cases and 115 controls), six considered vitamin B 12 (222 cases and 249 controls), and three considered vitamin D (513 cases and 5629 controls);

The NTG group: Two studies considered vitamin B 6 (90 cases and 82 controls), four considered vitamin B 12 (123 cases and 176 controls), and 0 considered vitamin D; and

The EXG group: Three studies considered vitamin B 6 (144 cases and 146 controls), six considered B 12 (228 cases and 240 controls), and one considered vitamin D (70 cases and 70 controls).

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“…Turgut et al [6] showed that the serum vitamin B 6 levels are significantly higher in POAG and NTG patients than in controls, but others reported no significant difference in serum vitamin B 6 levels among these groups [7,8,9]. Several studies have shown that serum vitamin B 12 levels are elevated in NTG, POAG, and EXG [6,10,11], but others have reported decreased levels of serum vitamin B 12 [9,12]. Moreover, although most studies have found that the serum vitamin D level is decreased in glaucoma patients compared with controls [13,14], the difference in vitamin D levels between glaucoma patients and controls is limited.…”

Circulating biomarkers in glaucoma, age-related macular degeneration, and diabetic retinopathy

“…Significant increase in plasma ET-1 and homocysteine levels in patients with POAG is related to vascular endothelial dysfunction. [12] Due to endothelial dysfunction, plasma ET-1 levels in glaucoma patients are five times higher than corresponding age-matched healthy controls. [13]…”