Abstract
Purpose The pathogenesis of keratoconus (KC) is multifactorial and associated with oxidative stress and subsequent DNA damage. The aim of this study was to investigate differences in DNA damage and replicative stress in patients with KC, and in both healthy and diseased controls.
Methods Sixty-four corneal buttons were obtained from 27 patients with KC after corneal transplant surgery, 21 patients with a decompensated graft (DG), and 16 healthy controls (HC). The amount of intact Alu elements per genome copy as measured by qPCR was used to quantify intact DNA. Telomere length was measured as a proxy for replicative stress. In addition, telomerase reverse transcriptase (hTERT) gene expression level was assessed.
Results Mean (±SD) DNA damage was similar between the KC (5.56 ±14.08), DG (3.16 ±8.22), and HC (3.51 ±6.66) groups (P=0.807). No associations were found between DNA damage and patient age (P=0.523), atopic constitution (P=0.240), or contact lens wear (P=0.393). Telomere length differed (P=0.034), most notably in the KC group, and hTERT was not detected in any corneal sample. Three cross-linked (CXL) KC corneas did not contain significant more DNA damage (2.6x, P = 0.750).
Conclusions Based on these findings, differences in actual corneal DNA damage in KC could not be identified, and the longer telomere length in KC did not support replicative stress as a major etiological factor in the pathogenesis of KC. Future longitudinal investigations on KC etiology should assess progressive early cases to better comprehend the cellular and molecular processes preceding the archetypical morphological changes.
Precis Oxidative stress is allegedly linked with the development of keratoconus. Whether these stressors actually lead to persisting DNA damage and replicative stress is debated. DNA damage was comparable with control samples, and a shortened telomere length was not identified.
Footnotes
Abbreviations: KC = keratoconus, HC = healthy control, DG = decompensated graft, ROS = reactive oxidative species, mtDNA = mitochondrial DNA, hTERT = humane telomerase reverse transcriptase, UV = ultraviolet, CXL = corneal crosslinking, TL = telomere length
