Evaluation of indoleamine 2,3-dioxygenase expression and kynurenine pathway metabolites levels in serum samples of diabetic retinopathy patients.
BACKGROUND
Diabetic retinopathy (DR) is the leading cause of acquired blindness. The involvement of indoleamine 2, 3-dioxygenase (IDO) and kynurenines, the products of tryptophan degradation in various pathological conditions was well documented.


OBJECTIVE
The aim of the present study was to determine the expression of IDO and levels of tryptophan metabolites in serum samples of DR patients.


METHODS
Tryptophan and its metabolites, i.e. kynurenine, kynurenic acid and 3-hydroxy kynurenine were measured by HPLC in serum of normal subjects as well as non-proliferative (NPDR) and proliferative DR (PDR) patients. The expression of IDO was measured using semi-quantitative reverse transcriptase polymerase chain reaction.


RESULTS
Elevated expression of IDO and levels of kynurenine, kynurenic acid and 3-hydroxykynurenine were observed in NPDR and a higher expression was observed in PDR. No significant change was noticed in levels of tryptophan.


CONCLUSIONS
An elevation in the concentrations of tryptophan metabolites and IDO expression was evident in diabetic retinopathy patients. The results indicate probable association of IDO and tryptophan metabolites with DR.
Physiology Division, Department of Zoology, University College of Science, Osmania University, Hyderabad, India.
Praveen Kumar
PK
Munipally
Satish G
SG
Agraharm
Vijay Kumar
VK
Valavala
Sridhar
S
Gundae
Naga Raju
NR
Turlapati
D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid; D003930:Diabetic Retinopathy / Q000097:blood* / Q000175:diagnosis / Q000473:pathology; D005260:Female; D015870:Gene Expression; D006801:Humans; D007194:India; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000097:blood* / Q000235:genetics; D007736:Kynurenic Acid / Q000097:blood*; D007737:Kynurenine / Q000031:analogs & derivatives* / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012720:Severity of Illness Index; D014364:Tryptophan / Q000097:blood*
D015415:Biomarkers; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; C005045:3-hydroxykynurenine; D007737:Kynurenine; D014364:Tryptophan; D007736:Kynurenic Acid