Structural and biochemical aspects of keratan sulphate in the cornea

Abstract

Keratan sulphate (KS) is the predominant glycosaminoglycan (GAG) in the cornea of the eye, where it exists in proteoglycan (PG) form. KS-PGs have long been thought to play a pivotal role in the establishment and maintenance of the array of regularly-spaced and uniformly- thin collagen fibrils which make up the corneal stroma. This characteristic arrangement of fibrils allows light to pass through the cornea. Indeed, perturbations to the synthesis of KS-PG core proteins in genetically altered mice lead to structural matrix alterations and corneal opacification. Similarly, mutations in enzymes responsible for the sulphation of KS-GAG chains are causative for the inherited human disease, macular corneal dystrophy, which is manifested clinically by progressive corneal cloudiness starting in young adulthood.

A Study of Host Corneal Endothelial Cells After Non-Descemet Stripping Automated Endothelial Keratoplasty

“…Bar = 100 mm. is due predominantly to the presence of collagen-bound sulfated proteoglycans 11 and chloride anions that are electrostatically associated with the matrix in a transient manner. 12,13 This swelling tendency is neutralized in the physiologically normal cornea by the continuous removal of bicarbonate ions from the corneal stroma by the metabolically active endothelial pump.…”

Keratan sulfate: An up-to-date review

“…Anyone could assume unexpected if undesirable structural changes on KS chains of the corneal PGs led to visual dysfunctions. And that is exactly what happens in certain visual disorders like macular corneal dystrophy and keratoconus [1,6,7]. While the former is characterized by defections or changes on the patterns of sulfation, the latter is occasioned by malfunctioning in KS chain formation.…”

“…In cornea, the high abundance of KSPGs is related in maintaining the proper hydration levels of this tissue. This is relevant in order to keep constant the transparency of the tissue [1,7]. This factor is extremely important to allow the light beams passing through and converging precisely at the retina in order to generate the right visual effect [1,7].…”

“…This is relevant in order to keep constant the transparency of the tissue [1,7]. This factor is extremely important to allow the light beams passing through and converging precisely at the retina in order to generate the right visual effect [1,7]. Anyone could assume unexpected if undesirable structural changes on KS chains of the corneal PGs led to visual dysfunctions.…”

“…Nonetheless, both disorders are occasioned by distortions in fibrils (collagens and PGs) organization in the cornea resulting increased opacity of the tissue [1,6,7]. The use of KS as an active ingredient in eye drops may help to restore the healthier condition.…”