Differential Expression of TXNIP Isoforms in the Peripheral Leukocytes of Patients with Acute Myocardial Infarction

Abstract

Background . Acute myocardial infarction (AMI) is the most serious type of coronary atherosclerotic heart disease (CAD). The pathological changes are characterized by atherosclerosis. Oxidative stress plays an important role in atherosclerosis. Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor and regulator of thioredoxin, could bind thioredoxin to regulate its expression and antioxidant activity negatively. The NCBI data show that there are two isoforms in TXNIP gene, namely, TXNIP1 and TXNIP2. Our previous studies have shown that TXNIP expression levels in patients with unstable angina pectoris (UAP) were increased compared with controls (CTR). However, no upregulation of TXNIP was detected in AMI patients. Methods . The leucocytes were isolated from peripheral venous blood, and total RNA of the leucocytes was extracted. Then, real-time quantitative PCR was performed. Results . mRNA levels of TXNIP2 in AMI were significantly increased compared with CTR (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>P</mml:mi><mml:mo>&lt;</mml:mo><mml:mn>0.05</mml:mn></mml:math>). However, the expression of TXNIP1 was downregulated in AMI, but the difference was not statistically significant (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>P</mml:mi><mml:mo>&gt;</mml:mo><mml:mn>0.05</mml:mn></mml:math>). Logistic regression analysis showed that TXNIP2 mRNA levels were significantly associated with AMI (OR = 2.207, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi>P</mml:mi><mml:mo>&lt;</mml:mo><mml:mn>0.05</mml:mn></mml:math>). Conclusions . The expression of TXNIP2, not TXNIP1, is upregulated in leukocytes of AMI patients, indicating that only TXNIP2 in circulating leucocytes may be involved in the pathogenesis of AMI.