Effect of the cholesteryl ester transfer protein genotypes on plasma lipid and lipoprotein levels in Vietnamese children

HDL Receptor in Schistosoma japonicum Mediating Egg Embryonation: Potential Molecular Basis for High Prevalence of Cholesteryl Ester Transfer Protein Deficiency in East Asia

Schistosomiasis is a life-threatening parasitic disease caused by blood flukes, Schistosomes. In its intestinal type, the parasites reside in visceral/portal veins of the human hosts and lay eggs to excrete in feces via intestinal tracts, and some of the aberrant eggs plug into the liver via the portal blood flow. Ectopic growth of these eggs causes fatal granulomatosis and cirrhosis of the liver. The parasites ingest nutrients from the host blood plasma by using nonspecific and specific transport via their body surface and alimentary tracts. It is especially important for the female adults to obtain lipid molecules because they synthesize neither fatty acids nor sterols and yet produce egg yolk. Low-density lipoprotein receptors have been identified in the body of the Schistosomes but their functions in the parasite life cycle have not clearly been characterized. On the other hand, CD36-related protein was identified in the body and the eggs of Asian blood fluke, Schistosoma japonicum, and characterized as a molecule that mediates selective uptake of cholesteryl ester from the host plasma high-density lipoproteins (HDLs). This reaction was shown crucial for their eggs to grow to miracidia. Interestingly, abnormal large HDL generated in lack of cholesteryl ester transfer protein (CETP) is a poor substrate for this reaction, and, therefore, CETP deficiency resists pathogenic ectopic growth of the aberrant parasite eggs in the liver. This genetic mutation is exclusively found in East Asia, overlapping with the current and historic regions of Schistosoma japonicum epidemic, so that this infection could be related to high prevalence of CETP deficiency in East Asia.

The loss-of-function mutation of CETP affects HDLc levels but not ApoA1 in patients with acute myocardial infarction

BACKGROUND AND AIMS

Loss of the cholesteryl ester transfer protein (CETP) function affects HDLc levels, but its effects on major HDL protein component ApoA1 are not well understood in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

We investigated the effects of an East Asian loss-of-function variant (rs2303790; p.D442G) in CETP gene on HDLc and ApoA1 levels and its relationship with AMI. A total of 2327 AMI patients and 2615 age- and sex-matched controls from INTERHEART-China study were included. In controls, both levels of HDLc (1.24 vs. 1.04 mmol/L, P = 0.001) and ApoA1 (1.48 vs. 1.37 mmol/L, P = 0.042) were significantly higher in CETP variant G allele carriers compared to CETP wildtype D allele carriers. In AMI patients, levels of HDLc were significantly higher (1.14 vs. 1.01 mmol/L, P = 0.013) while levels of ApoA1 were not statistically difference (1.31 vs. 1.32 mmol/L, P = 0.468) in CETP variant group compared to CETP wildtype group. Moreover, CETP variant is associated with HDLc increase, but is not associated with AMI risk (P = 0.564), even after adjusting for age, sex, history of hypertension and diabetes, waist to hip ratio, smoking, total cholesterol, LDL cholesterol, triglycerides, physical activity, depression, alcohol, vegetables and fruit consumption.

CONCLUSIONS

Loss of CETP function is associated with increased HDLc and ApoA1 levels in healthy subjects, and in AMI patients, it is associated with HDLc levels but not ApoA1 levels. The lack of association of CETP variant with AMI may be related to the inability to increase ApoA1 levels and warranted further studies.

Prevention of fatal hepatic complication in schistosomiasis by inhibition of CETP

Schistosoma japonicum, once endemic all the East Asia, remains as a serious public health problem in certain regions. Ectopic egg embryonation in the liver causes granulomatosis and eventually fatal cirrhosis, so that prevention of this process is one of the keys to reduce its mortality. The embryonation requires cholesteryl ester from HDL of the host blood for egg yolk formation, and this reaction is impaired from the abnormal large HDL in genetic cholesteryl ester transfer protein (CETP) deficiency. When CETP was expressed in mice that otherwise lack this protein, granulomatosis of the liver was shown increased compared to the wild type upon infection of Schistosoma japonicum. The CETP deficiencies accumulated exclusively in East Asia, from Indochina to Siberia, so that Shistosomiasis can be a screening factor for this accumulation. CD36 related protein (CD36RP) was identified as a protein for this reaction, cloned from the cDNA library of Schistosoma japonicum with 1880-bp encoding 506 amino acids. The antibody against the extracellular loop of CD36RP inhibited cholesteryl ester uptake from HDL and suppressed egg embryonation in culture. Therefore, inhibition of CETP is a potential approach to prevent liver granulomatosis and thereby fatal liver cirrhosis in the infection of Schistosoma japonicum.

Unique features of high-density lipoproteins in the Japanese: in population and in genetic factors

Despite its gradual increase in the past several decades, the prevalence of atherosclerotic vascular disease is low in Japan. This is largely attributed to difference in lifestyle, especially food and dietary habits, and it may be reflected in certain clinical parameters. Plasma high-density lipoprotein (HDL) levels, a strong counter risk for atherosclerosis, are indeed high among the Japanese. Accordingly, lower HDL seems to contribute more to the development of coronary heart disease (CHD) than an increase in non-HDL lipoproteins at a population level in Japan. Interestingly, average HDL levels in Japan have increased further in the past two decades, and are markedly higher than in Western populations. The reasons and consequences for public health of this increase are still unknown. Simulation for the efficacy of raising HDL cholesterol predicts a decrease in CHD of 70% in Japan, greater than the extent by reducing low-density lipoprotein cholesterol predicted by simulation or achieved in a statin trial. On the other hand, a substantial portion of hyperalphalipoproteinemic population in Japan is accounted for by genetic deficiency of cholesteryl ester transfer protein (CETP), which is also commonly unique in East Asian populations. It is still controversial whether CETP mutations are antiatherogenic. Hepatic Schistosomiasis is proposed as a potential screening factor for historic accumulation of CETP deficiency in East Asia.

Cholesteryl ester transfer protein TaqIB polymorphism and its association with serum lipid levels and longevity in Chinese Bama Zhuang population

BACKGROUND

TaqIB polymorphism in the cholesteryl ester transfer protein (CETP) gene has been reported to be associated with serum high-density lipoprotein cholesterol (HDL-C) levels and longevity in several populations, but controversial results also arose probably due to racial/ethnic diversity. Bama is a remote and mountainous county located in the northwest of Guangxi, People's Republic of China, which has been well known for its longevity for centuries. The current study was to investigate the possible association of CETP TaqIB polymorphism with serum lipid levels and longevity in the Bama Zhuang population.

METHODS

The CETP TaqIB genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism in 523 long-lived inhabitants (long-lived group, LG; aged 90-107 years) and 498 healthy controls without longevity family history (non-long-lived group, non-LG; aged 40-69 years) residing in Bama County.

RESULTS

The levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were higher but TG, HDL-C/LDL-C ratio and the prevalence of dyslipidemia were lower in LG than in non-LG (P < 0.001 for all). There were no differences in the allelic and genotypic frequencies between the two groups (P > 0.05). Serum HDL-C levels and HDL-C/LDL-C ratio in LG were different among the genotypes (P < 0.01 for each), the subjects with B2B2 and B1B2 genotyes had higher HDL-C levels and HDL-C/LDL-C ratio than the subjects with B1B1genotye, whereas the levels of TC and HDL-C in non-LG were different among/between the genotypes (P < 0.01 for each), the B2 allele carriers had lower TC and higher HDL-C levels than the B2 allele noncarriers. Serum TG and HDL-C levels and HDL-C/LDL-C ratio were correlated with genotypes in LG, whereas serum TC and HDL-C levels were associated with genotypes in non-LG (P < 0.05-0.001).

CONCLUSIONS

The association of CETP TaqIB polymorphism and serum lipid profiles is different between LG and non-LG in the Chinese Bama Zhuang population. CETP TaqIB polymorphism might be one of the longevity-related genetic factors in this population.

Interactions between alcohol intake and the polymorphism of rs708272 on serum high-density lipoprotein cholesterol levels in the Guangxi Hei Yi Zhuang population

Both alcohol consumption and the polymorphism of the cholesteryl ester transfer protein (CETP) TaqIB gene (rs708272) influence plasma high-density lipoprotein cholesterol (HDL-C) levels. However, their interactions on serum HDL-C levels is not well known. The present study was undertaken to detect the interactions between alcohol consumption and the rs708272 polymorphism on serum lipid levels in the Guangxi Hei Yi Zhuang population. Genotyping of the rs708272 in 342 nondrinkers and 416 drinkers aged 15-70 years was performed by polymerase chain reaction and restriction fragment length polymorphism. Interactions between rs708272 genotype and alcohol consumption was assessed using a cross-product term between genotypes and the aforementioned factor. Statistical significance was evaluated with analysis of co-variance. The frequency of B1 allele was 65.8% in nondrinkers and 64.7% in drinkers (P>.05), respectively. The frequencies of B1B1, B1B2, and B2B2 genotypes were 45.0%, 41.5%, and 13.5% in nondrinkers, and 41.3%, 46.6%, and 12.0% in drinkers (P>.05), respectively. The levels of HDL-C and apolipoprotein (Apo) AI in nondrinkers were higher in B2B2 genotype than in B1B1 genotype (P<.05 for each), whereas triglyceride (TG) levels in drinkers were higher in B1B1 genotype than in B1B2 genotype (P<.05). The levels of TG, HDL-C, Apo AI in B1B1 genotype, and HDL-C and Apo AI in B1B2 genotype were higher in drinkers than in nondrinkers (P<.05-.01), whereas the levels of low-density lipoprotein cholesterol (LDL-C) and Apo B in B2B2 genotype, and the levels of LDL-C in B1B1 genotype were lower in drinkers than in nondrinkers (P<.05-.01). The levels of HDL-C were positively correlated with female sex and genotype in nondrinkers (P<.001 for each), and were positively associated with age and alcohol consumption in drinkers (P<.005 and<.01, respectively). This study suggests that the B1 carriers benefited more from alcohol consumption than the B2 carriers in increasing serum HDL-C and Apo AI levels, and lowering LDL-C levels.

Association between the TaqIB polymorphism in the cholesteryl ester transfer protein gene locus and postprandial plasma lipoprotein levels in heterozygotes for familial hypercholesterolemia

BACKGROUND

We examined the influence of cholesteryl ester transfer protein TaqIB polymorphism on triglyceride (TG) response to an oral fat tolerance test (OFTT) in patients heterozygous for familial hypercholesterolemia (hFH).

METHODS

We genotyped 67 hFH patients (32 men and 35 postmenopausal women) who were subjected to an OFTT.

RESULTS

All B1 allele carriers had lower high-density lipoprotein cholesterol (HDL-C) levels (p=0.013) and higher postprandial TG response at 6 and 8 h (p=0.05 and p=0.04, respectively) compared to B2 allele carriers. Multiple regression analysis showed that in the hFH group with a positive response, the presence of the B2 allele was significantly related to lower levels of TG-area under the curve (AUC) (p<0.01) compared to B1, adjusting for age, gender and body mass index. In the hFH group with a negative response, although age and female gender had a significant effect on TG-AUC levels (p<0.01 for both), the allele type was not significantly related to the TG-AUC levels (p=0.99).

CONCLUSIONS

B2 carriers had a lower postprandial TG response compared to B1 carriers. There were no differences in TG levels between B1 and B2 carriers in patients with a negative OFTT response. Therefore, at higher TG concentration, the B2 allele may protect against an exaggerated postprandial TG increase and subsequent lowering of HDL-C.