The Risk Factors Of Coronaty Heart Disease In Pilots And The Association Between LOX-1 Gene Polymorphism And Coronary Heart Disease In Pilots

Background:Coronary heart disease (CHD) or myocardial infarction may unexpectedly happen in pilots. It will threaten the flight safety because of its potential to cause sudden in-flight incapacitation. The most important pathological factor is angiostenosis owing to coronary atherosclerosis. However the exact reason for atherosclerosis has been unclear. Many investigations have discovered the direct correlation between many risk factors and atherosclerosis. Many risk factors can injure endothelial cells, produce endothelial dysfunction and facilitate atherosclerosis. Only improving multiple factor risk spectra, it is possible to cut down the risk with CHD. So controlling risk factors is a fundamental task to reducing the prevalence of CHD. It is observed that three established risk factors for CHD (high serum total cholesterol, high blood pressure and cigarette smoking) account for at least four-fifths of the attributable risk of CHD in people aged 35-59 years. Then the distribution of risk factors concerned with CHD in our military pilots is unclear and whether the composition of risk factors is different from the common people is also unclear. Moreover, genetic factors are important in the genesis and development of CHD. Now several studies have attempted to identify an association of genetic polymorphism with CHD or acute myocardial infarction. The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) was first discovered by Sawamura et al in 1997. Studies have shown that LOX-1 is the major receptor for oxidized low-density lipoprotein (ox-LDL) in endothelial cells.LOX-1 is expressed in vascular endothelial cells, macrophages, vascular smooth muscle cells(VSMCs), fibroblast and platelets. LOX-1 expression is upregulated in several pathological conditions promoting the development of atherosclerosis, such as hypertension, diabetes, hyperlipidemia and high expression of LOX-1 is found in atherosclerosis lesions. Recently, a 3'-UTR C>T polymorphism of the LOX-1 gene has been reported to be associated with atherosclerosis and the risk of acute myocardial infarction. Whether there is the association between the polymorphism of LOX-1 gene and coronary heart disease in our military pilots still ,or whether the polymorphism may affect the risk factors of CHD ,need to investigate.Objective:1.To explore the prevalence of CHD risk factors among our military pilots and to analyze whether the composition of risk factors is different from the common people.2.Furthermore, to detect the 3'-UTR C>T polymorphism of the LOX-1 gene among pilots and to study the association of the polymorphism in the LOX-1 gene with CHD and risk factors of pilots.Methods:1. All 297 plots completed a questionnaire. The cross-sectional investigation method was used to collect the general state of health and biochemical risk factors, and to analyse the distribution of risk factors in these pilots. The statistical analysis was done by One-Way ANOVA and Logistic regression.2. Furthermore, the real-time fluorescent polymerase chain reaction technique was used in the study designed a case-control study..40 pilots was examined for the 3'-UTR C>T polymorphism of the LOX-1 gene: 20 pilots with CHD as the patients and 20 healthy pilots as the controls. The distribution of the LOX-1 gene polymorphism was compared between two groups and the association of LOX-1 gene polymorphism with CHD and risk factors was evaluated. The statistical analysis was done by Independent-sample t-test and Chi-square test.Results:1. A total of 297 pilots were surveyed. The prevalence of smoking and drinking were 62.63% and 60.94%,respectively.Almost half (48.82%) have unhealthy eating habit.38.72% were found to be overweight. Hyperlipidemia, hypertension and diabetes were present in 26.60%, 10.44% and 3.03% of the pilots, respectively. The constituent ratio of smoking and drinking were maximal in people aged 35-44 years. The composition of CHD risk factors in pilots is different from the common people, the prevalence of smoking, drinking, overweight and hyperlipidemia is higher, but the prevalence of hypertension and diabetes is lower. Multivariate logistic regression analysis showed that the following factors were the risk factors for CHD in pilots:age over 45,history of hypertension, family history of CHD, excessive cigarette smoking(cigarette index over 200 cigarette year),increasing of TC level and lowering of HDL-C level. The highest odd radio(OR) value of these factors listed above was age over 45(12.78), next is excessive cigarette smoking(10.12). All 297 pilots were divided into four groups according to cigarette index. The TC,TG, LDL-C,TC/HDL-C level in excessive smoking group were significantly higher than no smoking group, but the HDL level was significantly lower. (p value﹤0.05).2. The 3'-UTR C>T polymorphism of the LOX-1 gene was existing in pilots.There are three genotype: CC genotype, CT genotype and TT genotype. When there was no significant difference of general state of health and other laboratory datas between CHD pilots and healthy pilots, such as age, blood pressure, BMI, cigarette smoking, blood lipid level and homocysteine(Hcy), statistically significant difference was observed in allele or genotype distribution of the 3'-UTR C>T polymorphism between two groups. The frequency of T allele significantly increased in CHD pilots compared to healthy pilots(0.50 vs 0.275, p value﹤0.05 ), the frequency of CT+TT genotype also significantly increased(0.8 vs 0.5, p value﹤0.05).Furthermore, no significant associations were observed between the LOX-1 polymorphisms and plasma lipid levels, cigarette smoking, Hcy (p >0.05).Conclusions:1. Now risk factors of CHD were generally in our military pilots, the prevalence of smoking was highest. The composition of CHD risk factors in pilots is different from the common people, the prevalence of smoking, drinking, overweight and hyperlipidemia is higher, but the prevalence of hypertension and diabetes is lower. The risk factors related to pilots CHD were age over 45, history of hypertension, family history of CHD, excessive cigarette smoking, increasing of TC level and lowering of HDL-C level.2. Cigarette smoking may be one of factors effecting blood lipid level of our military pilots.3. The LOX-1 polymorphism was associated with CHD risk in pilots, carriers of the T allele(CT/TT) exhibited a significant association with CHD. No association was detected for the LOX-1 polymorphism with other risk factors, so the association between the LOX1 polymorphism and CHD risk may be independent.