Decreased serum bilirubin is associated with arterial stiffness in men

Longitudinal Associations Between Serum Bilirubin Level and Carotid Atherosclerosis Plaque in a Health Screening Population

This study aimed to determine the relationship between bilirubin levels and carotid atherosclerosis (CAS) in the health screening population. After propensity score matching, this retrospective cohort study included 4360 subjects who underwent health examinations regularly in Hebei General Hospital between January 2010 and December 2019 and had no carotid plaque at baseline. After an average follow-up of 26.76 months, the main endpoint Cox regression analysis of carotid plaques was performed. After adjusting the confounding factors, Cox regression analysis showed that when serum total bilirubin (TBIL) and unconjugated bilirubin (UCB) increased by 1 standard deviation (SD), the risk of carotid plaque decreased by 7.30% (95% confidence interval (CI): 2.80-11.60%) and 15.70% (95% CI: 11.40-19.80%), respectively. When conjugated bilirubin (CB) increased by 1 SD, the risk of carotid plaques increased by 24.3% (95% CI: 19.7-29.0%). TBIL and UCB levels were negatively associated with CAS, and CB levels were positively associated with CAS.

Molecular Physiology and Pathophysiology of Bilirubin Handling by the Blood, Liver, Intestine, and Brain in the Newborn

Bilirubin is the end product of heme catabolism formed during a process that involves oxidation-reduction reactions and conserves iron body stores. Unconjugated hyperbilirubinemia is common in newborn infants, but rare later in life. The basic physiology of bilirubin metabolism, such as production, transport, and excretion, has been well described. However, in the neonate, numerous variables related to nutrition, ethnicity, and genetic variants at several metabolic steps may be superimposed on the normal physiological hyperbilirubinemia that occurs in the first week of life and results in bilirubin levels that may be toxic to the brain. Bilirubin exists in several isomeric forms that differ in their polarities and is considered a physiologically important antioxidant. Here we review the chemistry of the bilirubin molecule and its metabolism in the body with a particular focus on the processes that impact the newborn infant, and how differences relative to older children and adults contribute to the risk of developing both acute and long-term neurological sequelae in the newborn infant. The final section deals with the interplay between the brain and bilirubin and its entry, clearance, and accumulation. We conclude with a discussion of the current state of knowledge regarding the mechanism(s) of bilirubin neurotoxicity.

Causal Associations Between Serum Bilirubin Levels and Decreased Stroke Risk: A Two-Sample Mendelian Randomization Study

OBJECTIVE

A number of epidemiological studies have reported that decreased serum bilirubin, an endogenous antioxidant, is associated with cardiovascular disease. However, previous Mendelian randomization analyses conducted using a single sample have shown no evidence of association. Approach and Results: A 2-sample summary Mendelian randomization study was performed by obtaining exposure and outcome data from separate nonoverlapping samples. We utilized data from the KoGES (Korean Genome and Epidemiology Study; n=25 406) and KCPS-II (Korean Cancer Prevention Study-II; n=14 541) biobank for serum bilirubin and stroke, respectively. Using KoGES, a total of 1784 single nucleotide polymorphisms associated with serum bilirubin levels were discovered using a genome-wide significance threshold (P<5×10^-8), of which 10 single nucleotide polymorphisms were identified as independent (R²<0.005) and adopted as genetic instruments. From KCPS-II, total and ischemic stroke cases were identified (n=1489 and n=686), with 12 366 acting as controls. Various 2-sample summary Mendelian randomization methods were employed, with Mendelian randomization estimates showing an inverse causal association between serum bilirubin levels and total stroke risk (odds ratio, 0.481 [95% CI, 0.234-0.988]; P=0.046). This association increased in magnitude when restricting the analysis to ischemic stroke cases (odds ratio, 0.302 [95% CI, 0.105-0.868]; P=0.026).

CONCLUSIONS

Our findings provide evidence of significant causal relationship between high levels of bilirubin and decreased stroke risk in Korean population in agreement with observational approaches. This highlights the potential for bilirubin to serve as a therapeutic target for oxidative stress-related diseases such as stroke and suggests that previous findings were not a consequence of unmeasured confounding.

Serum Bilirubin and Coronary Artery Disease: Intricate Relationship, Pathophysiology, and Recent Evidence

Coronary artery disease (CAD) is a major cause of morbidity, mortality, and healthcare expenditure. A number of environmental and genetic risk factors have been known to contribute to CAD. More recently, a number of studies have supported as well as opposed a possible protective benefit of bilirubin in CAD, since it has anti-inflammatory, antioxidant, and antiaggregatory properties that may reduce atherogenesis. It also shares associations with different forms of CAD, namely stable CAD, unstable angina pectoris, stable angina pectoris, and acute myocardial infarction. Lack of sufficient evidence, however, has failed to elucidate a causal relationship between serum bilirubin level and risk of CAD. Therefore, in this update, we attempted to simplify this intricate relationship between bilirubin and CAD, revisit the pathophysiology of disease, how bilirubin may be protective, and to summarize the findings of the current literature.

Serum adipocyte fatty acid-binding protein levels are associated with peripheral arterial disease in women, but not men, with type 2 diabetes mellitus

BACKGROUND

Adipocyte fatty acid-binding protein (A-FABP) has been recognized as an important player in macrophage cholesterol trafficking and inflammation, and may promote the development of atherosclerosis. To further elucidate the role of A-FABP in atherosclerosis in diabetes, we investigated the relationship between serum A-FABP concentrations and peripheral arterial disease (PAD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

In all, 488 inpatients with T2DM were enrolled in the study (254 men, 234 women; mean (±SD) age 57.3 ± 13.0 years). The severity of peripheral arterial stenosis was assessed by ultrasound examination. Serum A-FABP concentrations were determined by ELISA.

RESULTS

Serum A-FABP concentrations were significantly higher in patients with than without PAD (8.0 ± 3.3 vs 6.2 ± 1.6 ng/mL, respectively; P < 0.05). Interestingly, there was an obvious gender-related difference in PAD patients with T2DM, with the stenosis rate being higher for female than male T2DM patients in the third A-FABP tertile. Logistic regression analysis revealed that serum A-FABP concentrations were an independent risk factor for PAD in female T2DM patients (odds ratio 1.890, 95% confidence interval 1.041-3.432; P = 0.036), but not in male T2DM patients. Correlation analyses revealed that A-FABP concentrations were correlated with body mass index (BMI), diastolic blood pressure, urinary microalbumin, and serum creatinine in male patients, and with BMI, duration of T2DM, fasting blood glucose, and serum creatinine in female patients.

CONCLUSIONS

Serum A-FABP concentrations are closely associated with PAD in Chinese women with T2DM. The study findings suggest that A-FABP may be a more specific marker of PAD in diabetic women than men.

Association of serum bilirubin with longevity: Evidence from a retrospective longitudinal study and cross-sectional data

Bilirubin is a potent antioxidant and an important anti-inflammatory factor. Therefore, there has been an increasing focus on serum bilirubin as a negative risk factor of cardiovascular mortality in men and an indicator of improved survival in both sexes, but the direct mechanisms of these links and the causes of sex differences are not well understood. Moreover, the evidence from longitudinal studies on effects of bilirubin on longevity is limited. In this study, we retrospectively analyzed two groups of older adults to explore age-dependent changes in serum bilirubin levels and their associations with long-term survival in both sexes. Longitudinal data from 142 individuals (68 men and 74 women) aged 45 to 70 years were compared with cross-sectional data from 225 individuals (113 men and 112 women). The latter group was divided into four categories of survival, i.e. 53, 63, 68, and 76+ based on data on lifespan. ANOVA, t-test, and regression analysis were run. The analysis of the longitudinal data showed an increase in serum total bilirubin levels in men (0.3038e0.093x, R2 = 0.667) and women (0.1838e0.0187x, R2 = 0.950), while the analysis of cross-sectional data revealed a U-shaped pattern of age-related changes in men (0.001x2 - 0.1263x + 4.4524, R2 = 0.999) but an inverted U-shaped pattern in women (0.0006x2 + 0.072x - 1.6924, R2 = 0.195). On balance, these results suggest that elevated but normal bilirubin levels might confer a survival advantage in older men but not women. Alternatively, the positive relationship between serum total bilirubin and lifespan was not causal but coincidental. Further studies are needed to elucidate the direct mechanisms of the association between serum bilirubin levels and longevity in elderly people of both sexes.

Relationship Between Total Serum Bilirubin Levels and Carotid and Femoral Atherosclerosis in Familial Dyslipidemia

Objective—

Bilirubin is a potent antioxidant that has been inversely related to cardiovascular disease. There is little information on serum total bilirubin (TB) in relation to atherosclerosis in familial dyslipidemia. We assessed the association between TB and carotid and femoral atherosclerosis in this high-risk group.

Approach and Results—

We evaluated 464 individuals with familial dyslipidemia (56% men; median age, 48 years), 322 with familial hypercholesterolemia, and 142 with familial combined hyperlipidemia. Carotid and femoral arteries were imaged bilaterally with a standardized ultrasonographic protocol. Mean and maximum intima-media thickness and plaque presence (≥1.2 mm) and height were recorded. Cross-sectional associations between TB and atherosclerosis variables were investigated in multivariable-adjusted models, including lipid values and hypolipidemic drug use. Inflammatory markers (C-reactive protein, total leukocyte count, and lipoprotein[a]) were also determined. Increasing TB levels were associated with decreasing intima-media thickness of all carotid segments ( P <0.05, all). TB also related to carotid plaque, present in 78% of individuals, and to plaque burden (≥3 plaques), with odds ratios (95% confidence interval) 0.59 (0.36–0.98) and 0.57 (0.34–0.96) for each increase of 0.5 mg in TB, respectively. Findings were confirmed in a validation cohort of 177 subjects with nonfamilial dyslipidemia. Only the familial combined hyperlipidemia group, with higher inflammation-related markers, showed an inverse association between TB and femoral plaque height (β=−0.183; P =0.030).

Conclusions—

TB was inversely and independently associated with carotid plaque burden in familial and nonfamilial dyslipidemia. These findings support the use of TB as a biomarker of atherosclerosis in this high-risk group.

Increment of serum bilirubin as an independent marker predicting new-onset type 2 diabetes mellitus in a Korean population

BACKGROUND AND AIMS

Several cross-sectional studies reported that serum bilirubin concentrations had an inverse association with type 2 diabetes mellitus (T2DM) prevalence. The aim of the current study was to investigate the relationship between percentage change in bilirubin levels (PCB) and incident risk of T2DM using a longitudinal model.

METHODS AND RESULTS

22,084 participants who received regular health check-ups between 2006 and 2012 were enrolled. Multivariable-adjusted Cox regression models were used to determine the hazard ratio (HR) of incident T2DM based on PCB. PCB was determined by subtracting baseline serum bilirubin level (BB) from the bilirubin level at the end of follow-up or a year before the last date of diagnosis, dividing by BB and multiplying by 100. Compared to non-diabetics, BB was lower in the diabetic group at the initial visit. There were 20,098 participants without T2DM at the initial visit; 1253 new cases occurred during follow-up. As PCB increased, T2DM incidence also increased (P < 0.001). After adjusting for confounders, the HR of incident T2DM in the highest PCB quartile was 2.08 (95% confidence interval [CI] 1.76-2.46). This trend remained significant when PCB was analyzed as a continuous variable (HR for 1-SD increment, 1.25; 95% CI 1.19-1.31). Additional analysis comparing the rate of PCB during the follow-up period revealed that the serum bilirubin level of the Incident T2DM group increased before T2DM development and decreased rapidly thereafter compared to others (P < 0.001).

CONCLUSIONS

Bilirubin level increment over time is associated with T2DM development.

Bone mineral density is associated with left ventricular diastolic function in women

BACKGROUND

Low bone mineral density (BMD) and left ventricular (LV) diastolic function are associated with heart failure. However, little is known about the association between BMD and LV diastolic function.

HYPOTHESIS

BMD is independently related to LV diastolic function in women.

METHODS

We conducted a cross-sectional study of 432 women. Brachial-ankle pulse wave velocity (baPWV) and BMD measurements were performed. LV diastolic function and structure were assessed by echocardiographic examination.

RESULTS

BaPWV and the percentage of LV diastolic dysfunction increased with progressive bone loss. Moreover, partial correlation analysis demonstrated that BMD at spine L2-4 and at femoral neck were correlated with baPWV and LV diastolic function parameters after adjusting covariates. Multivariate logistic regression analysis revealed that osteoporosis was independently associated with LV diastolic dysfunction in women.

CONCLUSIONS

Osteoporosis is independently associated with LV diastolic dysfunction in women. A prospective study is needed to elucidate the effects of BMD on cardiac function in women.

Gallstone disease is associated with arterial stiffness progression

Gallstones have been linked to dyslipidemia, metabolic syndrome and cardiovascular disease. Arterial stiffness is an indicator of subclinical atherosclerosis. The aim of this study was to prospectively examine the relationship between gallstone disease and arterial stiffness progression in 347 men and 454 women. These subjects were followed for 7 years. Arterial stiffness progression was measured based on increases in brachial-ankle pulse wave velocity. Changes in brachial-ankle pulse wave velocity during the study period were significantly greater in patients with gallstones than in subjects without gallstones. After adjusting for multiple risk factors, gallstone disease was found to be a significant and independent predictor of brachial-ankle pulse wave velocity progression (β=0.189; P<0.001). In conclusion, gallstone disease is an independent predictor of arterial stiffness progression, even after adjusting for other cardiovascular risk factors.

Serum Bilirubin Is Inversely Associated with Increased Arterial Stiffness in Men with Pre-Hypertension but Not Normotension

OBJECTIVE

Serum bilirubin level has shown to be inversely associated with coronary atherosclerosis, and may serve as a protective biomarker of coronary artery disease. Serum bilirubin has also been shown to be negatively associated with brachial-ankle pulse wave velocity (baPWV) in men without a history of hypertension, and in men with hypertension. It is unknown whether such associations can be observed in the pre-hypertensive or normotensive population. This study thus aimed to investigate the relationship between serum bilirubin level and increased arterial stiffness in subjects with pre-hypertension and normotension for both genders.

METHODS

A cross-sectional sample of 3,399 apparently healthy subjects undergoing a medical check-up at National Cheng Kung University Hospital was enrolled between October 2006 and August 2009, after excluding subjects with serum total bilirubin level greater than 20.52 μmol/L. Increased arterial stiffness was defined as baPWV of 1,400 cm/s or higher as the dichotomous variable and bilirubin as the continuous variable.

RESULTS

Based on multiple linear regression analysis, serum bilirubin level was inversely associated with baPWV in non-hypertensive men (β = -0.066, p < 0.001) but not in non-hypertensive women. In addition, the inverse relationship between bilirubin level and baPWV was found statistically significant only in pre-hypertensive men (β = -0.110, p < 0.001). Multiple logistic regression analysis showed that serum bilirubin was inversely associated with increased arterial stiffness in men with pre-hypertension (odds ratio = 0.955, 95% confidence interval = 0.916-0.996, p < 0.05) but not normotension after adjustment for other confounding factors. However, the relationship between total bilirubin level and increased arterial stiffness did not reach statistical significance for female subjects with pre-hypertension and normotension.

CONCLUSION

Serum bilirubin is inversely associated with increased arterial stiffness in men with pre-hypertension but not normotension. The association between bilirubin level and arterial stiffness was not found significant in women.

Arterial stiffness and central arterial wave reflection are associated with serum uric acid, total bilirubin, and neutrophil-to-lymphocyte ratio in patients with coronary artery disease

OBJECTIVE

Total bilirubin (TB) was recently recognized as an endogenous anti-inflammatory and anti-oxidant molecule. Uric acid (UA) takes part in cardiovascular diseases by inducing oxidative stress, inflammation, and endothelial dysfunction. We assessed the relationship between serum TB levels, serum UA levels, and inflammatory status assessed by neutrophil-to-lymphocyte ratio (N/L) and arterial stiffness and arterial wave reflection in patients with a clinical diagnosis of coronary artery disease (CAD).

METHODS

We included 145 consecutive patients admitted with stable angina pectoris (SAP) or acute coronary syndrome (ACS). Blood samples were drawn at admission for complete blood count and biochemistry. Non-invasive pulse waveform analysis for the determination of augmentation index (AIx) and carotid-femoral pulse wave velocity (PWV) measurements were performed with the commercially available SphygmoCor system.

RESULTS

When patients were divided into tertiles of PWV and AIx, median N/L and median serum UA levels were the highest and mean TB levels were the lowest in the third tertile (p<0.001 for all). AIx and PWV were positively associated with serum UA and N/L and negatively associated with serum TB levels (p<0.001 for all). After adjustments for age, gender, heart rate, systolic blood pressure, and presence of diabetes, significant correlations persisted for N/L, UA, and TB in ACS patients (p<0.05). In the SAP group, TB was significantly negatively correlated with AIx and PWV, and UA was significantly positively correlated with PWV (p<0.05).

CONCLUSION

N/L ratio and serum UA and TB levels might be used to risk-stratify patients with respect to arterial stiffness in CAD patients, especially in the presence of ACS.

Neutrophil-lymphocyte ratio is associated with arterial stiffness in postmenopausal women with osteoporosis

OBJECTIVE

Systemic inflammation may be a common mechanism for the development of osteoporosis (OP) and atherosclerosis. Elevated arterial stiffness is an index of subclinical atherosclerosis. Recent studies found that neutrophil/lymphocyte ratio (NLR), is a useful marker of cardiovascular disease and a more powerful predictor than any other leukocyte subtypes. However, little research has been conducted to investigate the relationship between NLR and arterial stiffness measured by brachial-ankle pulse wave velocity (baPWV).

METHODS

In this cross-sectional study, we examined the relationship between NLR and baPWV in 512 subjects.

RESULTS

Compared to the control subjects, NLR and baPWV increased in patients with OP. Partial correlation analysis revealed that there was a significant correlation between NLR and baPWV after adjusting for confounding factors in OP. Multivariate linear regression analysis showed that NLR was a significant factor for increased baPWV in patients with OP (β=0.249, p<0.001). However, there was no association between NLR and baPWV in control subjects.

CONCLUSION

NLR and baPWV are elevated in OP. Moreover, NLR is independently associated with baPWV. Further studies are warranted to investigate whether anti-inflammatory treatment could improve arterial stiffness in postmenopausal women with OP.

Looking to the horizon: the role of bilirubin in the development and prevention of age-related chronic diseases

Bilirubin, the principal tetrapyrrole, bile pigment and catabolite of haem, is an emerging biomarker of disease resistance, which may be related to several recently documented biological functions. Initially believed to be toxic in infants, the perception of bilirubin has undergone a transformation: it is now considered to be a molecule that may promote health in adults. Data from the last decade demonstrate that mildly elevated serum bilirubin levels are strongly associated with reduced prevalence of chronic diseases, particularly cardiovascular diseases (CVDs), as well as CVD-related mortality and risk factors. Recent data also link bilirubin to other chronic diseases, including cancer and Type 2 diabetes mellitus, and to all-cause mortality. Therefore, there is evidence to suggest that bilirubin is a biomarker for reduced chronic disease prevalence and a predictor of all-cause mortality, which is of important clinical significance. In the present review, detailed information on the association between bilirubin and all-cause mortality, as well as the pathological conditions of CVD, cancer, diabetes and neurodegenerative diseases, is provided. The mechanistic background concerning how bilirubin and its metabolism may influence disease prevention and its clinical relevance is also discussed. Given that the search for novel biomarkers of these diseases, as well as for novel therapeutic modalities, is a key research objective for the near future, bilirubin represents a promising candidate, meeting the criteria of a biomarker, and should be considered more carefully in clinical practice as a molecule that might provide insights into disease resistance. Clearly, however, greater molecular insight is warranted to support and strengthen the conclusion that bilirubin can prevent disease, with future research directions also proposed.

Neutrophil-Lymphocyte ratio is associated with arterial stiffness in diabetic retinopathy in type 2 diabetes

AIMS

Diabetic retinopathy (DR) is the most common complication of type 2 diabetes mellitus (T2DM). Inflammation plays a considerable role in the pathogenesis of T2DM and DR. Emerging evidence revealed that the neutrophil-lymphocyte ratio (NLR) may be a useful marker of cardiovascular disease. The brachial-ankle pulse wave velocity (baPWV) is an indicator for early atherosclerotic changes. Therefore, this study aimed to investigate the association of NLR with baPWV in patients with DR.

METHODS

In this cross-sectional study, we investigated the relationship between NLR and baPWV in 402 participants. Participants were divided into the following three groups: 133 control subjects without T2DM; 138 diabetic subjects without DR; and 131 patients with DR.

RESULTS

NLR and baPWV were elevated both in T2DM and in DR. Moreover, compared to T2DM, NLR and baPWV were higher in DR. There was a positive correlation between NLR and baPWV in patients with T2DM and DR after adjusting confounding factors. Multiple linear regression analysis further revealed that NLR was an independent and significant determinant for elevated baPWV (for T2DM, β=0.170; p=0.041; for DR, β=0.188; p=0.022, respectively).

CONCLUSIONS

The findings showed that NLR and baPWV are elevated both in T2DM and in DR. In addition, NLR is independently associated with baPWV. Early detection of abnormal NLR levels may be helpful for the search of subclinical atherosclerosis in patients with T2DM and DR.

Inverse association between serum bilirubin levels and arterial stiffness in Korean women with type 2 diabetes

BACKGROUND

Considerable evidence suggests that bilirubin is a potent physiologic antioxidant that may provide important protection against cardiovascular disease (CVD) and inflammation. We investigated the relationship between serum total bilirubin (TB) levels and arterial stiffness, measured by the brachial-ankle pulse wave velocity (baPWV), in patients with type 2 diabetes.

METHODS

We conducted a cross-sectional analysis of 1,711 subjects with type 2 diabetes (807 men and 904 women; mean age, 57.1 years). The subjects were stratified based on gender-specific tertiles of TB values, and a high baPWV was defined as greater than 1,745 cm/s ( >75th percentile).

RESULTS

The serum TB concentration was negatively correlated with the duration of diabetes, HbA1c, the 10-year Framingham risk score, and baPWV and was positively correlated with high-density lipoprotein cholesterol and the eGFR in both genders. Inverse association between TB categories and unadjusted prevalence of high PWV was only observed in women. After adjusting for confounding factors, the TB levels were inversely associated with a greater risk of a high baPWV, both as a continuous variable [a 1-SD difference; odds ratio (OR), 0.70; 95% confidence interval (CI), 0.54-0.90; P = 0.005] and when categorized in tertiles (the highest vs. the lowest tertile; OR, 0.49; 95% CI, 0.28-0.85; P = 0.011) in women but not in men. The relationship remained significant even after adjusting for retinopathy and nephropathy.

CONCLUSIONS

Low TB levels were significantly associated with arterial stiffness in Korean women with type 2 diabetes. Our data suggested that bilirubin may protect against macrovascular disease in diabetic women.

Low serum bilirubin concentration is a predictor of chronic kidney disease

OBJECTIVE

Chronic kidney disease (CKD) is a worldwide public health problem. It is very important to identify the factors that affect CKD. Previous studies have reported that serum bilirubin concentration was positively correlated with renal function in a cross-sectional study. The aim of this study was to investigate the relationship between serum bilirubin concentration and the progression of CKD.

METHODS

A cohort study was performed on a consecutive series of 2784 subjects without CKD, defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m(2), at baseline. We analyzed the relationship between serum total bilirubin concentration at baseline and new-onset CKD in the general population.

RESULTS

We followed the subjects for a median period of 7.7 years. There were 1157 females and 1627 males, and 231 females and 370 males developed CKD during this period. Multiple Cox regression analyses revealed that serum total bilirubin concentration (hazard ratio (HR) per 1.0 μmol/L increase 0.97 (95% CI 0.95-0.99), P = 0.0084) in addition to age, gamma-glutamyl transpeptidase (GGT), uric acid (UA), creatinine and medication for hypertension in men and serum total bilirubin concentration (HR per 1.0 μmol/L increase 0.96 (95% CI 0.93-1.00), P = 0.0309) in addition to age, GGT, alanine aminotransferase, UA, creatinine and medication for dyslipidemia in women were independent predictors of new-onset CKD, after adjusting for confounders.

CONCLUSION

Our study demonstrated that serum total bilirubin concentration could be a novel risk factor for the progression of CKD, defined as eGFR <60 ml/min/1.73 m(2), in the general population.

ABCA1-dependent serum cholesterol efflux capacity inversely correlates with pulse wave velocity in healthy subjects

The capacity of HDL to induce cell cholesterol efflux is considered one of its main antiatherogenic properties. Little is known about the impact of such HDL function on vascular physiology. We investigated the relationship between ABCA1-dependent serum cholesterol efflux capacity (CEC), an HDL functionality indicator, and pulse wave velocity (PWV), an indicator of arterial stiffness. Serum of 167 healthy subjects was used to conduct CEC measurement, and carotid-femoral PWV was measured with a high-fidelity tonometer. J774 macrophages, labeled with [(3)H]cholesterol and stimulated to express ABCA1, were exposed to sera; the difference between cholesterol efflux from stimulated and unstimulated cells provided specific ABCA1-mediated CEC. PWV is inversely correlated with ABCA1-dependent CEC (r = -0.183; P = 0.018). Moreover, controlling for age, sex, body mass index, mean arterial pressure, serum LDL, HDL-cholesterol, and fasting plasma glucose, PWV displays a significant negative regression on ABCA1-dependent CEC (β = -0.204; 95% confidence interval, -0.371 to -0.037). The finding that ABCA1-dependent CEC, but not serum HDL cholesterol level (r = -0.002; P = 0.985), is a significant predictor of PWV in healthy subjects points to the relevance of HDL function in vascular physiology and arterial stiffness prevention.