Abstract P040: Quitting Smoking Reduces Lectin-like Low-density Lipoprotein Receptor-1 index, an Independent Cardiovascular Risk Marker of Vascular Inflammation
Authors: Komiyama Maki , Wada Hiromichi , Yamakage Hajime , Asahara Noriko , Shimada Sayaka , Morimoto Tatsuya , Takahashi Yuko , Hasegawa Koji 
Published: March 2022

Background:
Vessel walls Inflammation is involved in the destabilization of atherosclerotic plaques. Lectin-like low-density lipoprotein (LDL) receptor-1 (LOX-1) is an oxidized LDL receptor expressed in vascular cells and monocytes. The LOX index is calculated by multiplying the concentration of LOX-1 ligand containing apolipoprotein B with the concentration of soluble LOX-1. A high LOX index reflects an increased risk for stroke and myocardial infarction. Fortunately, the cardiovascular risk decreases within 2 years after smoking cessation. However, no study has investigated the potential of the LOX index as a cardiovascular risk marker in smokers, and the relationship between the LOX index and smoking cessation.

Purpose:
The present study investigated the change of cardiovascular risk marker, LOX index, after smoking cessation and the relationship between smoking-related factors and LOX index. In addition, the present study investigated the impact of smoking cessation on the LOX index.

Methods:
Relation of the clinical parameters to the LOX index was examined on 207 subjects (155 males and 52 females) at the first visit to our outpatient clinic for smoking cessation. All anti-smoking treatments were conducted according to the Standard Procedures for Anti-Smoking Treatment (originally issued in March 2006 by the Japanese Circulation Society, Japan Lung Cancer Society, and Japanese Cancer Association). The patients were treated with transdermal nicotine patches or the oral administration of varenicline. Among patients who attended our smoking cessation clinic, 94 subjects (62 males and 32 females) successfully quit smoking. We determined their LOX index at baseline on their first visit and repeated it 3 months after beginning smoking cessation to assess the impact of smoking cessation on the LOX index.

Results:
Sex-adjusted regression analysis and multivariate analysis identified three independent determinants of the LOX index, namely low-density lipoprotein-cholesterol (LDL-C; β = 0.273, p = 0.002), high-sensitivity C-reactive protein (β = 0.324, p &lt; 0.001), and expired carbon monoxide concentration reflecting the amount of smoking (β = 0.225, p = 0.008). Body mass index (BMI) significantly increased 3 months after the onset of smoking cessation (p < 0.001). However, the LOX index significantly decreased from baseline to 3 months (from 3.31 to 2.57; p &lt; 0.001), regardless of the rate of increase in BMI post-cessation.

Conclusions:
The LOX index is closely associated with hsCRP, a common inflammatory marker, suggesting that LOX-1 is involved in cardiovascular events by inducing vessel wall inflammation. Our results also suggest that the LOX index is useful for evaluating the effects of smoking cessation intervention on cardiovascular risk reduction. In addition, smoking cessation may induce a decrease in this cardiovascular risk marker, independently of weight gain.