Glycolysis in Patients with Age-Related Macular Degeneration



Kanako Yokosako 1, Tatsuya Mimura*, 1, Hideharu Funatsu 2, Hidetaka Noma 3, Mari Goto 1, Yuko Kamei 1, Aki Kondo 1, Masao Matsubara 1
1 Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
2 Department of Ophthalmology, Yachiyo Medical Center, Tokyo Women's Medical University, Chiba, Japan
3 Department of Ophthalmology, Hachioji Medical Center, Tokyo Medical University, Tokyo, Japan


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© Yokosako et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, 2-1-10 Nishiogu, Arakawa-ku, Tokyo 116-8567, Japan; Tel: +81-3-3810-1111, Ext. 7765; Fax: +81-3-3894-0282; E-mail: mimurat-tky@umin.ac.jp


Abstract

Purpose:

Retinal adenosine triphosphate is mainly produced via glycolysis, so inhibition of glycolysis may promote the onset and progression of age-related macular degeneration (AMD). When glycolysis is inhibited, pyruvate is metabolized by lactic acid fermentation instead of entering the mitochondrial tricarboxylic acid (TCA) cycle. We measured urinary pyruvate and lactate levels in patients with AMD.

Methods:

Eight patients with typical AMD (tAMD group) and 9 patients with polypoidal choroidal vasculopathy (PCV group) were enrolled. Urinary levels of pyruvate, lactate, α-hydroxybutyrate, and β-hydroxybutyrate were measured in all patients.

Results:

The mean urinary levels of pyruvate and lactate were 8.0 ± 2.8 and 7.5 ± 8.3 μg/mg creatinine (reference values: 0.5-6.6 and 0.0-1.6), respectively, with the mean increase over the reference value being 83.6 ± 51.1% and 426.5 ± 527.8%, respectively. In 12 patients (70.6%), the lactate/pyruvate ratio was above the reference range. Urinary levels of α-hydroxybutyrate and β-hydroxybutyrate were decreased by -31.9 ± 15.2% and -33.1 ± 17.5% compared with the mean reference values. There were no significant differences of any of these glycolysis metabolites between the tAMD and PCV groups. Multivariate analysis revealed that none of the variables tested, including patient background factors (age, hypertension, diabetes, hyperlipidemia, cerebrovascular disease, alcohol, smoking, visual acuity, and AMD phenotype), were significantly associated with the lactate/pyruvate ratio.

Conclusion:

A high lactate/pyruvate ratio is a well-known marker of mitochondrial impairment, and it indicates poor oxidative function in AMD. Our results suggest that increased lactate levels may be implicated in the pathogenesis of AMD.

Keywords: Age-related macular degeneration, glycolysis, ketone body, lactate, pyruvate.