Molecular Age-Related Changes in the Anterior Segment of the Eye

Effects of Aging on Intrinsic Protein Disorder in Human Lenses and Zonules

This study aims to compare the levels of intrinsic protein disorder within the human lens and zonule proteomes and investigate the role of aging as a potential influencing factor on disorder levels. A cross-sectional proteomic analysis was employed, utilizing a dataset of 1466 proteins derived from the lens and zonule proteomes previously published by Wang et al. and De Maria et al. Bioinformatics tools, including a composition profiler and a rapid intrinsic disorder analysis online tool, were used to conduct a comparative analysis of protein disorder. Statistical tests such as ANOVA, Tukey's HSD, and chi-squared tests were applied to evaluate differences between groups. The study revealed distinct amino acid compositions for each proteome, showing a direct correlation between aging and increased protein disorder in the zonular proteomes, whereas the lens proteomes exhibited the opposite trend. Findings suggest that age-related changes in intrinsic protein disorder within the lens and zonule proteomes may be linked to structural transformations in these tissues. Understanding how protein disorder evolves with age could enhance knowledge of the molecular basis for age-related conditions such as cataracts and pseudoexfoliation, potentially leading to better therapeutic strategies.

Genetic drivers of m6A methylation in human brain, lung, heart and muscle

The most prevalent post-transcriptional mRNA modification, N⁶-methyladenosine (m⁶A), plays diverse RNA-regulatory roles, but its genetic control in human tissues remains uncharted. Here we report 129 transcriptome-wide m⁶A profiles, covering 91 individuals and 4 tissues (brain, lung, muscle and heart) from GTEx/eGTEx. We integrate these with interindividual genetic and expression variation, revealing 8,843 tissue-specific and 469 tissue-shared m⁶A quantitative trait loci (QTLs), which are modestly enriched in, but mostly orthogonal to, expression QTLs. We integrate m⁶A QTLs with disease genetics, identifying 184 GWAS-colocalized m⁶A QTL, including brain m⁶A QTLs underlying neuroticism, depression, schizophrenia and anxiety; lung m⁶A QTLs underlying expiratory flow and asthma; and muscle/heart m⁶A QTLs underlying coronary artery disease. Last, we predict novel m⁶A regulators that show preferential binding in m⁶A QTLs, protein interactions with known m⁶A regulators and expression correlation with the m⁶A levels of their targets. Our results provide important insights and resources for understanding both cis and trans regulation of epitranscriptomic modifications, their interindividual variation and their roles in human disease.

Incidence, Risk, and Visual Outcomes after Repositioning of Acute Non-Traumatic Flap Dislocations Following Femtosecond-Assisted LASIK

Although the use of femtosecond lasers instead of mechanical devices has decreased the incidence of flap complications following laser-assisted in situ keratomileusis (LASIK), dislocations and striae still occur. Flap repositioning is an effective intervention to improve visual outcomes after acute flap complications in both microkeratome-assisted and femtosecond-assisted LASIK. This retrospective case series included patients undergoing flap repositioning secondary to acute flap dislocation and/or visually significant striae within the first two weeks following femtosecond LASIK (FS-LASIK) from 2015 to 2020 at a single institution. Preoperative, intraoperative, and postoperative de-identified data were analyzed for incidence, risk factors, and visual acuity outcomes. The incidence of flap repositioning was 0.35% in 21,536 eyes (n = 70). Indications for repositioning included acute flap dislocation (35.7%) and visually significant striae (64.3%). High myopia (OR = 3.04, p = 0.001) and patient age over 50 years (OR = 3.69, p = 0.001) were the strongest risk factors for these complications. Prior to flap repositioning, uncorrected distance visual acuity (UDVA) of 20/20 or better and 20/40 or better occurred in 19% and 57% of eyes, respectively. After repositioning, a final UDVA of 20/20 or better and 20/40 or better occurred in 78% and 98% of eyes, respectively. After repositioning, one line of UDVA was lost in two eyes (2.8%) and two lines were lost in one eye (1.4%). Risk factors for acute flap dislocation included high myopia and age over 50 years. Flap repositioning was effective in salvaging visual outcomes.

Regenerative and Antioxidant Properties of Autologous Platelet-Rich Plasma Can Reserve the Aging Process of the Cornea in the Rat Model

Aging is a natural progressive decline in the biological function of cells. Age-related changes in the cornea can affect its ability to refract light or repair itself. Platelet-rich plasma (PRP) has a promising role in regenerative medicine and evidenced its efficacy in multiple fields, but in corneal aging has not yet been elucidated. The present work was performed to estimate the regenerative antioxidant effect of PRP on corneal aging in rats. Rats were assigned into two main groups: (GI) adult group and (GII) aged group. The adult group was divided into GIa (adult rats), GIb (adult-saline treated), and GIc (adult-PRP treated). The aged group was divided into GIIa (aged rats) and GIIb (aged, PRP treated). PRP was administered by a single subconjunctival injection. After 10 days, histological, ultrastructural, immunohistochemical, and morphometrical investigations were carried out. Examination of the corneal sections of the aged group revealed corneal epithelial thinning, shedding of the surface epithelium with loss of desmosomal junction, and irregularity in Bowman's membrane. Disorganized widely spaced collagen bundles and neovascularization were detected in corneal stroma associated with thickening in Descemet's membrane. Ultrastructural examination revealed shrunken hyperchromatic nuclei, swollen mitochondria, and scanty cytoplasm with a strong nuclear reaction for caspase-3 immunostaining. Moreover, antioxidant/free radicals' imbalance was detected by the increase of malondialdehyde (MDA) level with a decrease of glutathione peroxidase (GPx) and superoxide dismutase (SOD) levels. In contrast, GIIb (aged, PRP treated) section examination revealed a restoration of the thickness of the corneal epithelial layer and Descemet's membrane with an amendment of collagen fiber regularity that is associated with weak nuclear reaction to caspase-3 and recovery of the balance in the redox state. These findings proved the effectiveness of PRP as a promising regenerative treatment for the age-associated changes in the cornea.

Interplay between Oxidative Stress, Inflammation, and Amyloidosis in the Anterior Segment of the Eye; Its Pathological Implications

There are different pathologies associated with amyloidogenic processes caused by the increase of reactive oxygen species (ROS) and the overactivation of inflammatory responses. These alterations are present in different regions of the anterior segment of the eye, and they have been associated with the development and progression of ocular pathologies, such as glaucoma, dry eye syndrome, keratitis, and cataracts among other pathologies. Aim. To discuss briefly the anatomical characteristics of the anterior segment of the eye and describe the interaction between oxidative stress (OS) and inflammatory responses, emphasizing the misfolding of several proteins leading to amyloidogenic processes occurring in the anterior segment and their implications in the development of ocular diseases. We performed a search on PubMed, CINAHL, and Embase using the MeSH terms “eye,” “anterior segment”, “inflammation”, “oxidative stress”, and “amyloidosis”. The search encompassed manuscripts published up to April 2019. A hundred forty-four published studies met the inclusion criteria. We present the current knowledge regarding the interaction between OS and the activation of inflammatory processes and how both can cause conformational changes in several peptides and proteins in each compartment of the anterior segment. However, we found that there is no consensus about which factor is the first to cause amyloidosis. Our conclusions suggest that there is an interplay among these factors forming a vicious cycle that leads to the loss of protein structure in ocular pathologies, and multifactorial therapies should be developed to avoid protein misfolding and to stop the progression of ocular pathologies.