Thiol–Disulfide Homeostasis and Serum Ischemia Modified Albumin Levels in Patients with Primary Open–Angle Glaucoma

The Relationship Between Vitamin-D Deficiency and Protein Oxidation Among Obese Children

Aim: The aim of the study is to examine the relationship between obesity, Vitamin-D deficiency, and protein oxidation. Methods: Thiol-disulfide homeostasis, Vitamin-D, ischemia modified albumin, insulin, and lipid levels were compared among obese, pre-obese and normal-weight healthy children. Results: A total of 136 children (69 boys and 67 girls) were included in the study. The vitamin-D levels of obese children were lower than those of pre-obese and normal weight (p < 0.05). In the normal weight group, total thiol and native thiol were lower in the pubertal period than in adolescence; were higher in those with sufficient Vitamin-D level than those with insufficient and deficient Vitamin-D (p < 0.05). Vitamin-D level was lower in pre-obese girls than boys (p < 0.05). Those with high triglycerides had high disulfide/total thiol, disulfide, and disulfide/native thiol and low native thiol/total thiol (p < 0.05). Conclusion: Thiol-disulfide homeostasis is negatively affected by low vitamin D levels, pubertal period and high triglyceride levels.

A Novel Biomarker in Primary Glaucoma: Aqueous Humor and Serum Levels of Ischemia Modified Albumin (IMA)

PURPOSE

To analyze ischemia-modified albumin (IMA) levels in aqueous humor and serum, and their correlation to RNFL thinning in primary glaucoma patients.

DESIGN

Cross-sectional study.

METHODS

Patients were divided into the control and glaucoma groups. The control group was patients with senile cataracts. The glaucoma group consisted of patients diagnosed for the first time as primary open-angle glaucoma (POAG) or primary angle closure glaucoma (PACG). Exclusion criteria were secondary glaucoma and patients with systemic disease. A complete cataract examination was done for all patients, and glaucoma examinations for the glaucoma group. In both groups, the IMA aqueous humor was obtained during cataract and glaucoma procedure. Serum levels of IMA, malondialdehyde (MDA), and tumor necrosis factor alpha (TNF-α) were examined during preoperative examinations.

RESULTS

Control group comprised 33 participants, and glaucoma group 41 patients (21 PACG and 20 POAG). Mean IMA aqueous humor (AQH) levels found in cataract group 6.039±3.16 ng/mL, glaucoma group 14.89±6.08 ng/mL, PACG group 12.69±6.25 ng/mL and POAG group 17.33±4.988 mg/mL. Mean IMA serum levels in cataract group 14.75±6.53 ng/mL, glaucoma group 13.89±6.53 ng/mL, PACG group 12.79±6.46 ng/mL± and POAG group 14.93±10.74 ng/mL. Glaucoma group had significant higher level of IMA in aqueous humor compared to control group, but opposite findings in serum IMA levels between groups. POAG patients had a higher aqueous IMA level compared to PACG group and correlated significantly with IOP. IMA AQH also negatively correlated to the RNFL thickness in both POAG and PACG group. Cut off 9.5 ng/mL was considered as a normal limit value to differentiate between control and glaucoma group.

CONCLUSION

Primary glaucoma patients showed a significantly increased level of IMA AQH as a local ischemic biomarker compared to the control group. Systemic oxidative activity is not a representation of local ocular oxidative stress in both cataract and glaucoma group.

Ischemia Modified Albumin (IMA) as a New Biomarker in the Ophthalmology Field: A Brief Literature Review

Purpose:

This study aimed to review the potential role of ischemia-modified albumin as a biomarker for diagnostic modalities in the ophthalmology field.

Methods:

Articles were reviewed without a specific date. A manual search was also performed by reviewing reference lists of meta-analyses and systematic reviews. All articles were reviewed, and a total of 18 articles were selected by the authors.

Results:

Oxidative stress increases structural and functional damage to proteins in many ocular diseases. The human serum albumin is a major circulating protein with antioxidative and anti-inflammatory properties. Oxidative stress has been shown to be an important part of etiology and pathogenesis in ocular diseases related to ischemia. Biomarkers that are specific to oxidative stress and ischemia-related ocular pathogenesis are needed to provide an extensive understanding regarding diagnosis, monitoring progression, and new potential target treatment. Ischemia-modified albumin (IMA) as a new promising biomarker might be useful in the early detection and treatment of ocular diseases with ischemic pathogenesis.

Conclusion:

IMA plays an important role in the progression of ophthalmology diseases, such as diabetic retinopathy, hypertensive retinopathy, cataract progression, seasonal allergies, and glaucoma. Further studies are needed to elaborate these results as a consideration in new testing modalities in clinical practice as well as a new target therapy research.

Clinical Significance of Albumin- and Bilirubin-Based Biomarkers in Glaucoma: A Retrospective Case-Control Study

Glaucoma is the second leading cause of global blindness. The etiology of glaucoma is complicated. In addition to elevated intraocular pressure (IOP), several other mechanisms have been implicated in pathogenesis, such as oxidative stress and systemic inflammation. Serum albumin (ALB) and bilirubin (BIL) have been reported to have potent antioxidant properties and contribute to maintain redox homeostasis in various diseases. However, associations between these parameters and glaucoma remain mostly unknown. Here, we conducted a retrospective case-control study, revealing that serum ALB, total BIL (TBIL), and indirect BIL (IBIL) levels were markedly lower in glaucoma patients than those in healthy controls. Furthermore, the neutrophil-to-ALB (NAR), neutrophil-to-TBIL (NTBR), and neutrophil-to-IBIL (NIBR) ratios were greatly higher in glaucoma. Additionally, interestingly, lower ALB and BIL levels and higher NAR, NTBR, and NIBR were associated with severer glaucomatous visual impairment, and NAR, NTBR, and NIBR showed good accuracy as diagnostic tests for glaucoma severity, suggesting these indices might be useful as discriminative biomarkers for disease severity. Our current findings demonstrate associations between ALB, BIL, NAR, NTBR, NIBL, and glaucoma. It might be useful to use NAR, NTBR, and NIBR as predictive markers for disease severity and employ ALB/BIL as alternative therapy or adjuvant medicines in glaucoma patients.

Oxidative Stress in Optic Neuropathies

Increasing evidence indicates that changes in the redox system may contribute to the pathogenesis of multiple optic neuropathies. Optic neuropathies are characterized by the neurodegeneration of the inner-most retinal neurons, the retinal ganglion cells (RGCs), and their axons, which form the optic nerve. Often, optic neuropathies are asymptomatic until advanced stages, when visual impairment or blindness is unavoidable despite existing treatments. In this review, we describe systemic and, whenever possible, ocular redox dysregulations observed in patients with glaucoma, ischemic optic neuropathy, optic neuritis, hereditary optic neuropathies (i.e., Leber's hereditary optic neuropathy and autosomal dominant optic atrophy), nutritional and toxic optic neuropathies, and optic disc drusen. We discuss aspects related to anti/oxidative stress biomarkers that need further investigation and features related to study design that should be optimized to generate more valuable and comparable results. Understanding the role of oxidative stress in optic neuropathies can serve to develop therapeutic strategies directed at the redox system to arrest the neurodegenerative processes in the retina and RGCs and ultimately prevent vision loss.

Candidate Glaucoma Biomarkers: From Proteins to Metabolites, and the Pitfalls to Clinical Applications

Glaucoma is an insidious group of eye diseases causing degeneration of the optic nerve, progressive loss of vision, and irreversible blindness. The number of people affected by glaucoma is estimated at 80 million in 2021, with 3.5% prevalence in people aged 40-80. The main biomarker and risk factor for the onset and progression of glaucoma is the elevation of intraocular pressure. However, when glaucoma is diagnosed, the level of retinal ganglion cell death usually amounts to 30-40%; hence, the urgent need for its early diagnosis. Molecular biomarkers of glaucoma, from proteins to metabolites, may be helpful as indicators of pathogenic processes observed during the disease's onset. The discovery of human glaucoma biomarkers is hampered by major limitations, including whether medications are influencing the expression of molecules in bodily fluids, or whether tests to validate glaucoma biomarker candidates should include human subjects with different types and stages of the disease, as well as patients with other ocular and neurodegenerative diseases. Moreover, the proper selection of the biofluid or tissue, as well as the analytical platform, should be mandatory. In this review, we have summarized current knowledge concerning proteomics- and metabolomics-based glaucoma biomarkers, with specificity to human eye tissue and fluid, as well the analytical approach and the main results obtained. The complex data published to date, which include at least 458 different molecules altered in human glaucoma, merit a new, integrative approach allowing for future diagnostic tests based on the absolute quantification of local and/or systemic biomarkers of glaucoma.

[Accumulation of sulfur and phosphorus in the eye's drainage system in primary open-angle glaucoma]

PURPOSE

To analyze the chemical composition of the sclera and trabecular meshwork in patients with primary open-angle glaucoma (POAG) and to assess the impact of corneal-compensated intraocular pressure (IOP) on the chemistry of the drainage area.

MATERIAL AND METHODS

Biopsy specimens of the trabecular meshwork (89 specimens) and sclera (41 specimens) obtained from patients with POAG on maximal medical therapy were analyzed to determine the content of certain chemical elements - carbon (C), nitrogen (N), oxygen (O), aluminum (Al), calcium (Ca), chlorine (Cl), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P), silicon (Si) and sulfur (S). The elements were selected based on chemical structure target tissue and sensitivity of the method used for analysis. Visualization was performed using the «EVO LS 10» (Zeiss, Germany) scanning electron microscope (SEM), and the chemical composition was studied with the «Oxford-X-MAX-50» (Oxford, UK) energy-dispersive spectrometer (EDS). Statistical analysis was performed using the Spearman correlation.

RESULTS

The IOP of patients with POAG was found to have positive correlation with the total amount of S, P, and Ca in the trabecular meshwork. The accumulation of sulfur-containing compounds associated with pigment granules in trabecular meshwork's tissue was identified. A correlation was determined between the organic and inorganic (mineral) phosphorus content in the trabeculae, and the IOP values. The organic component of phosphorus was better represented than the mineral component in patients with increased IOP.

CONCLUSION

In patients with POAG, an increase in the IOP level causes the amount of S associated with pigment granules and the proportion of organic P to increase in the trabecular meshwork, which should be taken into account in the further search for drug therapy that would potentially affect pathologically altered tissue.

Ischemia-Modified Albumin Levels and Thiol-Disulphide Homeostasis in Diabetic Macular Edema in Patients with Diabetes Mellitus Type 2

PURPOSE

It was aimed to assess the role of thiol-disulphide homeostasis and ischemia-modified albumin (IMA) level in the development of diabetic macular edema (DME) in patients with diabetes mellitus type 2 (T2DM).

MATERIALS AND METHODS

Sixty-six study patients were divided into two groups. Group I included 43 patients with T2DM and DME, and Group 2 included 23 patients with T2DM without eye involvement. A novel colorimetric method was used to assess thiol-disulphide homeostasis. Between the two groups IMA, total anti-oxidant, and total oxidant levels were measured and compared.

RESULTS

In Group 1, total and native thiol levels and disulphide levels were lower compared to Group 2 (p = .025, p < .001 and p = .013, respectively). Disulphide/native thiol, disulphide/total thiol ratios and native thiol/total thiol were similar between the groups. Total anti-oxidant level (TAL) reduced whereas total oxidant level (TOL) increased in Group 1 compared to Group 2 (p = .001, p = .002, respectively). Albumin level decreased, whereas IMA level increased in Group 1 compared to Group 2 (p < .001 for both).

CONCLUSIONS

The disruption in thiol/disulphide homeostasis, increased IMA and oxidative stress have an impact on the development of diabetic macular edema.