Correlation of Aqueous Humor Lysyl Oxidase Activity with TGF-ß Levels and LOXL1 Genotype in Pseudoexfoliation.
Pseudoexfoliation (PXF) is a microfibrillopathy involving disordered elastogenesis. Abnormal extracellular matrix (ECM) production underlies the pathophysiology of PXF. The enzyme Lysyl oxidase (LOX) and its isoforms are known to cross-link the elastin and collagen. Though the etiopathogensis of PXF is not well understood, studies report on the genetic risk involving LOXL1 gene. This study aims to screen LOXL1 coding variants rs1048661 and rs3825942 in the South Indian population and the implication of the single nucleotide polymorphism (SNP) with LOX activity. The levels of transforming growth factor β (TGF-β) in aqueous humor and its correlation with the LOX activity were also examined.



Blood, plasma, and aqueous aspirates were prospectively collected from PXF cases with and without glaucoma and cataract cases as controls. DNA was extracted from 48 PXF cases without glaucoma, 12 PXF cases with glaucoma, and 40 age-matched cataract-alone controls without PXF/glaucoma for analyzing LOX SNPs. LOX activity was measured in aqueous humor and plasma of 30 PXF cases without glaucoma, 24 age-matched cataract-alone controls without PXF/glaucoma, and 14 PXF cases with glaucoma. Protein levels of LOX, LOXL1, LOXL2, and total TGF-β were estimated in plasma and aqueous humor by ELISA.



The specific activity of LOX in aqueous humor was found to be significantly lowered in PXF cases compared with cataract-alone controls (p = 0.014). This decrease in LOX activity in PXF cases was associated with high-risk GG haplotype. However, this was not statistically significant and a larger sample size is warranted. TGF-β1 and TGF-β2 negatively correlated with LOX activity in aqueous humor (p = 0.028; p = 0.046, respectively).



The LOXL1 SNPs, rs1048661 and rs3825942, are associated with PXF in the South Indian population correlating with lowered LOX activity in the aqueous humor. The increased level of total TGF-β in the aqueous humor of PXF cases is possibly associated with LOX regulation which needs further investigation.
a R.S. Mehta Jain Department of Biochemistry and Cell Biology , Vision Research Foundation, KNBIRVO , Sankara Nethralaya, Chennai , India.
Ramakrishnan
R
Gayathri
a R.S. Mehta Jain Department of Biochemistry and Cell Biology , Vision Research Foundation, KNBIRVO , Sankara Nethralaya, Chennai , India.
Karunakaran
K
Coral
b SNONGC Department of Genetics and Molecular Biology , Vision Research Foundation, KNBIRVO , Sankara Nethralaya, Chennai , India.
Ferdinamarie
F
Sharmila
b SNONGC Department of Genetics and Molecular Biology , Vision Research Foundation, KNBIRVO , Sankara Nethralaya, Chennai , India.
Sarangapani
S
Sripriya
c JCOC , Sankara Nethralaya , Chennai , India.
Krishnamoorthy
K
Sripriya
d Department of Glaucoma , Medical Research Foundation , Sankara Nethralaya, Chennai , India.
Panday
P
Manish
d Department of Glaucoma , Medical Research Foundation , Sankara Nethralaya, Chennai , India.
B
B
Shantha
d Department of Glaucoma , Medical Research Foundation , Sankara Nethralaya, Chennai , India.
George
G
Ronnie
d Department of Glaucoma , Medical Research Foundation , Sankara Nethralaya, Chennai , India.
Lingam
L
Vijaya
a R.S. Mehta Jain Department of Biochemistry and Cell Biology , Vision Research Foundation, KNBIRVO , Sankara Nethralaya, Chennai , India.
Angayarkanni
A
Narayanasamy
D000368:Aged; D000594:Amino Acid Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D001082:Aqueous Humor / Q000378:metabolism*; D016022:Case-Control Studies; D004247:DNA / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D017889:Exfoliation Syndrome / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D008249:Protein-Lysine 6-Oxidase / Q000235:genetics* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism
D016212:Transforming Growth Factor beta; D004247:DNA; D000594:Amino Acid Oxidoreductases; C445313:LOXL1 protein, human; D008249:Protein-Lysine 6-Oxidase
Lysyl oxidase; pseudoexfoliation; transforming growth factor-β