Effects of altered metabolites in the aqueous humor of glaucoma patients on human trabecular meshwork cells character

概要

Objective: Glaucoma is a major cause of visual impairment and blindness, and elevated intraocular pressure (IOP) is a major risk factor for glaucoma. Human trabecular meshwork (HTM) dysfunction plays a key role in impaired aqueous humor (AH) outflow and elevated IOP in glaucoma. Despite extensive studies, the underlying pathological mechanisms of HTM dysfunction leading to glaucoma are not fully understood. The aim of this study was to investigate metabolic markers associated with elevated IOP in AH samples from glaucoma patients and to investigate their effect of identified metabolites on human trabecular meshwork cells (HTMCs) phenotype, thus reflect their role in IOP elevation.

Methods: AH samples were collected from the patients in control and glaucoma subjects and analyzed with Global metabolomics to identify the metabolic markers associated with glaucoma in AH. Then, we performed a spearman analysis to analyze the correlation between the identified metabolites and clinical parameters. The contraction of collagen mediated by HTMCs was evaluated by culturing the HTMCs in collagen gels and measuring the change in the diameter of the collagen gels. The HTMCs cytoskeletal changes were examined by actin filaments (F-actin) staining of rhodamine phalloidin stained HTMCs. DAPI was used as nuclear counterstain. The expression of alpha-smooth muscle actin (α-SMA) was evaluated by Western blot analyses. Transforming growth factor beta-1 (TGF-β1) was used as a positive control.

Results: Glucaric acid, sulfolactic acid and cystine were proved to be positively correlated with IOP in glaucoma. We chose three typical experiments to investigate the effects of glucaric acid, sulfolactic acid, cystine on the HTMCs morphology. However, trabecular meshwork (TM) cell-mediated contraction of collagen gels was like the untreated group after identified metabolites or glucaric acid concentration gradient treatments. After treated with identified metabolites, no significant alterations in the HTMCs cytoskeletal changes were observed in comparison to the negative control group. And no significant α-SMA overexpression was found in three identified metabolites stimulated HTMCs, particularly glucaric acid.

Conclusions: Our data suggest that glucaric acid, sulfolactic acid and cystine are positively correlated with IOP in glaucoma, however, these three target metabolites alterations in the AH exerted unobvious effect on HTMCs morphology and function in vitro.