Presence and distribution of l-kynurenine aminotransferases immunoreactivity in human cataractous lenses

Abstract

ABSTRACT.Purpose: To investigate the presence and distribution of l-kynurenine aminotransferases immunoreactivity in human and animal lenses during cataract formation. Methods: Immunohistochemistry was conducted using polyclonal antibodies against KAT I, KAT II and KAT III on sections of 26 anterior capsules from patients undergoing surgical treatment of anterior subcapsular cataract (ASC) and 22 cataractous lenses from human eyes enucleated because of choroidal malignant melanoma. Additionally, the eyes of 11-month-old DBA ⁄ 2J mice (6 eyes) were investigated (with KAT I and II). Ten clear human lenses and four BL6 mice lenses were used as controls. Spatial immunoreactivity patterns of enzymes were compared with Periodic Acid -Schiff (PAS)-stained sections. Results: Immunohistochemical analysis revealed presence of KAT I, KAT II and KAT III in extracellular structures of all studied types of cataract in human eyes showing specific pattern of the stain. In cortical cataract, immunoreactivity was observed on cortical lens fibres. In nuclear cataract, KAT II revealed stronger and diffused staining than KAT I. Additionally, both KAT showed more pronounced staining at the edge of small clefts. In normal human lenses, KAT I, II and III, immunoreactivity was not observed. Presence of KAT I and KAT II in the intercellular substance of DBA ⁄ 2J mice cataract was observed. In BL6 mice lenses without cataract, only weak KAT I and KAT II staining was observed. Conclusions: Presence of l-kynurenine aminotransferases in extracellular matrix (ECM) during human cataract formation suggests that products of l-kynurenine pathway might be involved in mechanisms of cataractogenesis.

Photosensitizing Activity of Endogenous Eye Lens Chromophores: An Attempt to Unravel Their Contributions to Photo‐Aging and Cataract Disease

“… determined the enzymatic activity of kynurenine aminotransferase in senile cataractous lenses, but no activity was detected in young lenses. These data are in agreement with a recent report in which the expression of L‐kynurenine aminotransferases (I, II and III) were analyzed by immunohistochemistry in human cataractous eye lenses, and these enzymes were found only in human cataractous lenses (nuclear and cortical) and not in normal lenses . The presence of xanthurenic acid 8‐O‐ β ‐glucoside has been reported in human cataractous lenses , but no xanthurenic acid was detected when normal human lenses were analyzed .…”

Determination of Tryptophan and Its Major Metabolites in Fluid from the Anterior Chamber of the Eye in Diabetic Patients with Cataract by Liquid Chromotography Mass Spectrometry (LC-MS/MS)

“…The examination of TRP metabolites levels has been studied in brain tissue and amniotic fluid [ 4 ], serum [ 5 , 6 ] cerebrospinal fluid [ 7 ], human cataracts’ lenses [ 8 ] and saliva of a diabetic patient [ 9 ]. There is also evidence that the KP pathway is connected with visual function as KYN and 3-OH-KYN glycoside derivatives act as UV filters and protect the retina and the lens by absorbing the UV radiation [ 8 , 10 , 11 , 12 , 13 , 14 ]. On the other hand, the kynurenine pathway-derivatives were identified as compounds inducing that is, cataract formation [ 8 , 10 , 14 ].…”