[Correlations of telomere length changing and pathogeny of keratoconus].
OBJECTIVE
To study telomere length, senescence-associated-beta-galactosidase (SA-beta-galactosidase) and senescence marker protein-30 (SMP-30) in the stromal cells of keratoconus or normal corneas respectively, aiming finding the association of these indexes with the phenotype of keratoconus.


METHODS
Experiment research. 37 keratoconus lesions corneas were removed from 32 keratoconus patients who were operated in Shangdong Eye Institute between January 2006 and December 2006, and 20 normal corneas were collected from eye bank. The keratoconus corneas ages were from 13 to 34 years [mean ages (19 + or - 5) years] and the control group consists of 20 normal corneas donor ages from 9 to 30 years [mean ages (19 + or - 4) years]. And there was no statistical difference of ages between keratoconus and normal corneas. Southern blot method was utilized to detect telomere length of genomic DNA. SA-beta-galactosidase was detected by 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal) staining method respectively in keratoconus and normal corneas. Isolated mRNA from keratoconus and normal corneas were reverse-transcribed to cDNA and SMP-30 was detected using PCR with specific primers (sense: 5' ccg tgg atg cct ttg act at 3'; anti-sense: 5' caa ctt cat gc tgct ttg ga 3'). To compare normal corneas and keratoconus corneas by histopathological study. Statistical analysis by t test.


RESULTS
The telomere length in stromal cells in keratoconus corneas were from 10.29 to 14.12 kb, mean (11.54 + or - 1.41) kb, while that of normal corneas were from 12.64 to 15.32 kb, mean (13.45 + or - 0.99) kb. The difference of telomere length in stromal cells of keratoconus and normal corneas reached a statistical significant level (t = 4.753, P < 0.05). That means the telomere length of keratoconus stroma was shorter than that of normal corneal stroma. Light microscopy revealed that collagen fibers in keratoconus corneal stroma were arranged in an irregular manner. Cells density in keratoconus stroma appeared lower than in normal ones but the decrease was not significant. The staining of SA-beta-galactosidase in the keratoconus section was evident, but there was no staining in the normal corneas. SMP-30 was not detectable with RT-PCR method in either keratoconus or normal corneas.


CONCLUSIONS
Telomeres in the keratoconus stromas manifest higher SA-beta-galactosidase than control, implying that improper senescence might be involved in pathogenesis of keratoconus.
Wang
Jiao-jiao
JJ
Shangdong Eye Institute, Qingdao 266071, China.
Li
Shao-wei
SW
Wang
Yi-qiang
YQ
Wang
Ye
Y
Zhong
Wen-xian
WX
Zang
Xin-jie
XJ
D000293:Adolescent; D000328:Adult; D000375:Aging; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002648:Child; D003319:Corneal Stroma / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007640:Keratoconus / Q000378:metabolism* / Q000473:pathology; D008297:Male; D016615:Telomere / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D055815:Young Adult; D001616:beta-Galactosidase / Q000378:metabolism
D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C513323:RGN protein, human; D001616:beta-Galactosidase