Thioredoxin-interacting protein is required for endothelial NLRP3 inflammasome activation and cell death in a rat model of high-fat diet. Diabetologia 2014 Feb;57(2):413-23
Date
11/10/2013Pubmed ID
24201577Pubmed Central ID
PMC3947289DOI
10.1007/s00125-013-3101-zScopus ID
2-s2.0-84893663061 (requires institutional sign-in at Scopus site) 125 CitationsAbstract
AIMS/HYPOTHESIS: Obesity and hypertension, known pro-inflammatory states, are identified determinants for increased retinal microvascular abnormalities. However, the molecular link between inflammation and microvascular degeneration remains elusive. Thioredoxin-interacting protein (TXNIP) is recognised as an activator of the NOD-like receptor pyrin domain containing-3 (NLRP3) inflammasome. This study aims to examine TXNIP expression and elucidate its role in endothelial inflammasome activation and retinal lesions.
METHODS: Spontaneously hypertensive (SHR) and control Wistar (W) rats were compared with groups fed a high-fat diet (HFD) (W+F and SHR+F) for 8-10 weeks.
RESULTS: Compared with W controls, HFD alone or in combination with hypertension significantly induced formation of acellular capillaries, a hallmark of retinal ischaemic lesions. These effects were accompanied by significant increases in lipid peroxidation, nitrotyrosine and expression of TXNIP, nuclear factor κB, TNF-α and IL-1β. HFD significantly increased interaction of TXNIP-NLRP3 and expression of cleaved caspase-1 and cleaved IL-1β. Immunolocalisation studies identified TXNIP expression within astrocytes and Müller cells surrounding retinal endothelial cells. To model HFD in vitro, human retinal endothelial (HRE) cells were stimulated with 400 μmol/l palmitate coupled to BSA (Pal-BSA). Pal-BSA triggered expression of TXNIP and its interaction with NLRP3, resulting in activation of caspase-1 and IL-1β in HRE cells. Silencing Txnip expression in HRE cells abolished Pal-BSA-mediated cleaved IL-1β release into medium and cell death, evident by decreases in cleaved caspase-3 expression and the proportion of live to dead cells.
CONCLUSIONS/INTERPRETATION: These findings provide the first evidence for enhanced TXNIP expression in hypertension and HFD-induced retinal oxidative/inflammatory response and suggest that TXNIP is required for HFD-mediated activation of the NLRP3 inflammasome and the release of IL-1β in endothelial cells.
Author List
Mohamed IN, Hafez SS, Fairaq A, Ergul A, Imig JD, El-Remessy ABMESH terms used to index this publication - Major topics in bold
AnimalsCarrier Proteins
Caspase Inhibitors
Cell Cycle Proteins
Cell Death
Diet, High-Fat
Endothelial Cells
Eye Diseases
Inflammasomes
Inflammation
Male
Microcirculation
NF-kappa B
NLR Family, Pyrin Domain-Containing 3 Protein
Obesity
Oxidative Stress
Rats
Rats, Wistar
Receptors, Cytoplasmic and Nuclear
Retina