Decreased Serum Bilirubin Is Associated With Silent Cerebral Infarction

Atazanavir-induced unconjugated hyperbilirubinemia prevents vascular hyporeactivity during experimental human endotoxemia

Objective

Inflammation-induced free radical release is important in the pathogenesis of several diseases, including atherosclerosis and sepsis. Heme oxygenase (HO) breaks down heme into carbon monoxide, iron, and biliverdin. Biliverdin IXα is directly converted to bilirubin by biliverdin reductase. Unconjugated bilirubin is a powerful antioxidant, and elevated levels have beneficial effects in preclinical models and human cardiovascular disease. However, its impact during acute inflammation in humans is unknown. In the present study, we investigated the impact of atazanavir-induced (unconjugated) hyperbilirubinemia on antioxidant capacity, inflammation, and vascular dysfunction in human experimental endotoxemia.

Approach and results

Following double-blinded four-day treatment with atazanavir 2dd300 mg (or placebo), twenty healthy male volunteers received 2 ng/kg Escherichia coli lipopolysaccharide intravenously. Blood was drawn to determine the bilirubin levels, antioxidant capacity, and cytokine response. It was demonstrated that following atazanavir treatment, total bilirubin concentrations increased to maximum values of 4.67 (95%CI 3.91-5.59) compared to 0.82 (95%CI 0.64-1.07) mg/dL in the control group (p<0.01). Furthermore, the anti-oxidant capacity, as measured by the ferric-reducing ability of plasma (FRAP), was significantly increased with 36% in hyperbilirubinemia subjects (p<0.0001), and FRAP concentrations correlated strongly to bilirubin concentrations (R2 = 0.77, p<0.001). Hyperbilirubinemia attenuated the release of interleukin-10 from 377 (95%CI 233-609) to 219 (95%CI 152-318) pg/mL (p=0.01), whereas the release of pro-inflammatory cytokines remained unaltered. In vitro, in the absence of hyperbilirubinemia, atazanavir did not influence lipopolysaccharide-induced cytokine release in a whole blood assay. Vascular function was assessed using forearm venous occlusion plethysmography after intra-arterial infusion of acetylcholine and nitroglycerin. Hyperbilirubinemia completely prevented the LPS-associated blunted vascular response to acetylcholine and nitroglycerin.

Conclusions

Atazanavir-induced hyperbilirubinemia increases antioxidant capacity, attenuates interleukin-10 release, and prevents vascular hyporesponsiveness during human systemic inflammation elicited by experimental endotoxemia.

Clinical trial registration

http://clinicaltrials.gov, identifier NCT00916448.

Association between bilirubin levels with incidence and prognosis of stroke: A meta-analysis

Objective

Bilirubin has anti-inflammatory, antioxidant, and neuroprotective properties, but the association between bilirubin and stroke remains contentious. A meta-analysis of extensive observational studies on the relationship was conducted.

Methods

Studies published before August 2022 were searched in PubMed, EMBASE, and Cochrane Library. Cohort, cross-sectional and case-control studies that examined the association between circulating bilirubin and stroke were included. The primary outcome included the incidence of stroke and bilirubin quantitative expression level between stroke and control, and the secondary outcome was stroke severity. All pooled outcome measures were determined using random-effects models. The meta-analysis, subgroup analysis, and sensitivity analysis were performed using Stata 17.

Results

A total of 17 studies were included. Patients with stroke had a lower total bilirubin level (mean difference = -1.33 μmol/L, 95% CI: -2.12 to -0.53, P < 0.001). Compared with the lowest bilirubin level, total odds ratio (OR) of the highest bilirubin for the occurrence of stroke was 0.71 (95% CI: 0.61-0.82) and ischemic stroke was 0.72 (95% CI: 0.57-0.91), especially in cohort studies with accepted heterogeneity (I 2 = 0). Serum total and direct bilirubin levels were significantly and positively associated with stroke severity. A stratified analysis based on gender showed that the total bilirubin level in males correlated with ischemic stroke or stroke, which was not noted in females.

Conclusion

While our findings suggest associations between bilirubin levels and stroke risk, existing evidence is insufficient to establish a definitive association. Better-designed prospective cohort studies should further clarify pertinent questions (PROSPERO registration number: CRD42022374893).

Risk factors for relapse and nomogram for relapse probability prediction in patients with minor ischemic stroke

BACKGROUND

The identification of risk factors for recurrence in patients with minor ischemic stroke (MIS) is a critical medical need.

AIM

To develop a nomogram for individualized prediction of in-hospital recurrence in MIS patients.

METHODS

Based on retrospective collection, a single-center study was conducted at the First Affiliated Hospital of Anhui Medical University from January 2014 to December 2019. Univariate and multivariate logistic regression analyses were used to determine the risk factors associated with MIS recurrence. The least absolute shrinkage and selection operator regression was performed for preliminary identification of potential risk factors. Uric acid, systolic blood pressure, serum total bilirubin (STBL), and ferritin were integrated for nomogram construction. The predictive accuracy and calibration of the nomogram model were assessed by the area under the receiver operating characteristic curve (AUC-ROC) and Hosmer-Lemeshow test, respectively.

RESULTS

A total of 2216 MIS patients were screened. Among them, 155 were excluded for intravascular therapy, 146 for unknown National Institutes of Health Stroke Scale score, 195 for intracranial hemorrhage, and 247 for progressive stroke. Finally, 1244 patients were subjected to further analysis and divided into a training set (n = 796) and a validation set (n = 448). Multivariate logistic regression analysis revealed that uric acid [odds ratio (OR): 0.997, 95% confidence interval (CI): 0.993-0.999], ferritin (OR: 1.004, 95%CI: 1.002-1.006), and STBL (OR: 0.973, 95%CI: 0.956-0.990) were independently associated with in-hospital recurrence in MIS patients. Our model showed good discrimination; the AUC-ROC value was 0.725 (95%CI: 0.646-0.804) in the training set and 0.717 (95%CI: 0.580-0.785) in the validation set. Moreover, the calibration between nomogram prediction and the actual observation showed good consistency. Hosmer-Lemeshow test results confirmed that the nomogram was well-calibrated (P = 0.850).

CONCLUSION

Our present findings suggest that the nomogram may provide individualized prediction of recurrence in MIS patients.

Serum Bilirubin Levels and Extent of Symptomatic Intracranial Atherosclerotic Stenosis in Acute Ischemic Stroke: A Cross-Sectional Study

Background: Bilirubin plays a paradoxical role in the pathological mechanism of stroke. To date, few clinical studies have investigated the effect of serum bilirubin on symptomatic intracranial atherosclerotic stenosis (sICAS). This study aims to evaluate the connection between serum bilirubin and sICAS.

Methods: From September 2015 to May 2020, 1,156 sICAS patients without hepatobiliary diseases admitted to our hospital were included. Patients were distributed into none-mild (0–49%), moderate (50–69%) and severe-occlusion sICAS groups (70–100%) by the degree of artery stenosis. Moderate and severe-occlusion sICAS patients were classified into three groups by the number of stenotic arteries (single-, two- and multiple-vessel stenosis). The relationship between serum bilirubin levels and sICAS was analyzed by logistic regression analysis.

Results: In univariable analyses, sICAS patients with severe and multiple atherosclerotic stenoses had lower levels of total bilirubin (Tbil), direct bilirubin (Dbil), and indirect bilirubin (Ibil). In multinomial logistic regression analyses, when compared with the highest tertile of bilirubin, lower levels of Tbil, Dbil, and Ibil showed higher risks of severe-occlusion sICAS (95% CI: 2.018–6.075 in tertile 1 for Tbil; 2.380–7.410 in tertile 1 for Dbil; 1.758–5.641 in tertile 1 for Ibil). Moreover, the logistic regression analyses showed that lower levels of Tbil, Dbil, and Ibil were related to multiple (≥3) atherosclerotic stenoses (95% CI: 2.365–5.298 in tertile 1 and 2.312–5.208 in tertile 2 for Tbil; 1.743–3.835 in tertile 1 and 1.416–3.144 in tertile 2 for Dbil; 2.361–5.345 in tertile 1 and 1.604–3.545 in tertile 2 for Ibil) when compared with tertile 3.

Conclusions: Our findings suggest that lower bilirubin levels may indicate severe and multiple intracranial atherosclerotic stenoses.

Association between serum bilirubin concentration and Parkinson's disease: a meta-analysis

Background:

The antioxidant effects of bilirubin in Parkinson's disease (PD) have recently gained much attention from the research community. However, results from these studies have been conflicting. This meta-analysis is conducted to assess the relationship between the serum bilirubin concentration and the risk of PD.

Methods:

Two reviewers performed a systematic literature search across five databases (MEDLINE, PubMed, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials). The case-control studies regarding bilirubin levels in PD patients published up to April 2020 were included. These studies were subjected to rigorous scrutiny and data extraction to determine the standard mean difference (SMD) and the 95% confidence interval (CI), which were analyzed using the Stata V.12.0 statistical software.

Results:

A total of eight studies which included 1463 PD cases and 1490 controls were incorporated into our meta-analysis. SMD analysis showed that there was a higher total bilirubin (TBIL) and direct bilirubin (DBIL) levels in PD patients compared with controls (for TBIL, SMD: 0.300, 95% CI: 0.050–0.549, P = 0.018; for DBIL, SMD: 0.395, 95% CI: 0.102–0.688, P = 0.008). However, no significant relationship was found between the serum indirect bilirubin and PD patients (SMD: −0.223, 95% CI: −0.952–0.505, P = 0.548). A subgroup analysis based on ethnicity indicated that the serum TBIL was higher in PD patients of Caucasian descent in contrast to matched healthy controls (SMD: 0.511, 95% CI: 0.324–0.698, P = 0.000, I² = 58.0%).

Conclusion:

Higher serum bilirubin levels in PD patients suggest that bilirubin might play a role in the pathogenesis of PD and have the potential to be utilized as a biochemical marker for PD diagnosis and treatment.

Abnormal Serum Bilirubin/Albumin Concentrations in Dementia Patients With Aβ Deposition and the Benefit of Intravenous Albumin Infusion for Alzheimer's Disease Treatment

Background

Our previous study in animal models revealed that bilirubin could induce Aβ formation and deposition. Bilirubin may be important in neurodegenerative dementia with Aβ deposition. Hence, lowering the concentration of the free bilirubin capable of crossing the blood brain-barrier may benefit the treatment of Alzheimer's disease (AD).

Objectives

The objectives of this study were to examine the change in the serum bilirubin and albumin concentrations of dementia patients with Aβ deposition, and to determine the effects of intravenous administration of albumin in the treatment of AD.

Methods

Bilirubin and albumin concentrations in dementia patients with Aβ deposition were examined. Cell viability and apoptosis were determined in dopaminergic neuron-like cells MN9D treated with bilirubin in the presence of diverse concentrations of serum. Human albumin at a dose of 10 g every 2 weeks for 24 weeks was administered intravenously to AD patients to examine the effect of albumin on AD symptoms.

Results

Significantly higher indirect bilirubin (IBIL) concentrations, lower albumin concentrations, and higher ratio of IBIL to albumin (IBIL/ALB) were observed in dementia patients with Aβ deposition, including AD, dementia with Lewy bodies, and general paresis of insane. In vitro assays showed that bilirubin-induced injury in cultured dopaminergic neuron-like cells negatively depends on the concentration of serum in the culture medium. General linear model with repeated measures analysis indicated a main effect of group on the change in albumin concentrations and Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory scale (ADCS-ADL) scores, and the main effect of time and group, and group-by-time interaction on the change of Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB) scores. Analysis of the combined data of the entire 28 weeks of assessment period using the area under curve convincingly showed significantly improvements in the change of albumin concentrations, ADCS-ADL scores, and CDR-SB scores.

Conclusion

IBIL and the IBIL/ALB ratio are significantly higher in dementia patients with Aβ deposition, and intravenous administration of albumin is beneficial to AD treatment.

Trial Registration

The intervention study was registered at http://www.chictr.org.cn (ChiCTR-IOR-17011539). Date of registration: June 1, 2017.

Lower Serum Indirect Bilirubin Levels are Inversely Related to Carotid Intima-Media Thickness Progression

BACKGROUND

Bilirubin has been recognized as a potential endogenous inhibitor of atherosclerosis, being inversely associated with carotid intima-media thickness (CIMT). However, little information is available concerning the correlation between serum indirect bilirubin (IBIL), especially long-term IBIL level, and early atherosclerosis progression. This study was designed to evaluate the relationship between serum IBIL level and CIMT progression.

METHODS

A total of 2205 participants were enrolled in this Asymptomatic Polyvascular Abnormalities Community study (APAC study). CIMT was measured at baseline and 2-year follow-up. The participants were divided into four groups based on their serum IBIL levels at baseline. Both baseline and average serum IBIL values during the 2-year follow up were used in the analysis. Multivariable logistic regression and linear regression were used to assess the associations between serum IBIL and CIMT progression.

RESULTS

The results showed that 51.93% (1145/2205) of participants were diagnosed with CIMT progression during the 2-year follow-up. Baseline serum IBIL level was significantly associated with the incidence of CIMT progression after adjusting for other potential confounding factors. Compared with the first quartile, adjusted odds ratios (OR) of the second, third, and fourth quartiles of IBIL were 0.70 [95% confidence interval (CI), 0.55-0.90], 0.68 (95% CI, 0.52-0.87), and 0.63 (95% CI, 0.49-0.82) (P = 0.0006), respectively. Serum IBIL level during the follow-up was also associated with CIMT progression in the univariate analysis (P = 0.0022), although no longer significant after adjusting for potential confounders in the multiple linear regression.

CONCLUSION

The study demonstrated the inverse relationship between serum IBIL and CIMT progression. Lower serum IBIL level is an independent predictor of subclinical atherosclerosis.

Serum bilirubin and ischaemic stroke: a review of literature

Bilirubin, a product of heme metabolism, is the most potent endogenous antioxidant which increases in many oxidative stress conditions such as stroke. It has been widely known to exert neuroprotective effect on stroke through mechanisms involved in development, therefore, it can influence the occurrence and prognosis of ischaemic stroke (IS). In this review, studies were identified by a comprehensive search of Pubmed, Embase, the Cochrane Library (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Methodology Register) and Web of Science to examine the correlation between serum bilirubin levels and risks of developing IS as well as IS outcomes. Additional studies were identified by reviewing references and contacting authors.

Baseline Serum Bilirubin and Risk of First Stroke in Hypertensive Patients

Background

Data on the association between serum bilirubin and the risk of stroke are limited and inconclusive. We aimed to evaluate the association between serum bilirubin and the risk of first stroke and to examine any possible effect modifiers in hypertensive patients.

Methods and Results

Our study was a post hoc analysis of the CSPPT (China Stroke Primary Prevention Trial). A total of 19 906 hypertensive patients were included in the final analysis. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and 95% CIs for the risk of first stroke associated with serum bilirubin levels. The median follow‐up period was 4.5 years. When serum total bilirubin was assessed as tertiles, the adjusted HR of first ischemic stroke for participants in tertile 3 (12.9–34.1 μmol/L) was 0.75 (95% CI, 0.59–0.96), compared with participants in tertile 1 (<9.3 μmol/L). When direct bilirubin was assessed as tertiles, a significantly lower risk of first ischemic stroke was also found in participants in tertile 3 (2.5–24.8 μmol/L) (adjusted HR, 0.77; 95% CI, 0.60–0.98), compared with those in tertile 1 (<1.6 μmol/L). However, there was no significant association between serum total bilirubin (tertile 3 versus 1: adjusted HR, 1.45; 95% CI, 0.89–2.35) or direct bilirubin (tertile 3 versus 1: adjusted HR, 1.27; 95% CI, 0.76–2.11) and first hemorrhagic stroke.

Conclusions

In this sample of Chinese hypertensive patients, there was a significant inverse association between serum total bilirubin or direct bilirubin and the risk of first ischemic stroke.

The Relationship Between Serum Bilirubin Levels and Peripheral Arterial Disease and Gender Difference in Patients With Hypertension: BEST Study

We evaluated the relationship between serum bilirubin levels and ankle-brachial index (ABI) to determine whether gender affected the relationship between bilirubin levels and peripheral arterial disease (PAD) in patients with hypertension. A total of 543 patients were included in our studies (78 patients with PAD and 465 without PAD). Peripheral arterial disease was defined as ABI <0.90 for either and/or both sides. Serum bilirubin levels were measured with a vanadate oxidation method by using fasting venous blood samples. Serum total bilirubin (TBiL) and direct bilirubin (DBiL) levels were higher in males compared with females (both P < .05). Total bilirubin and DBiL were significantly lower in the PAD group. After adjustment for cardiovascular risk factors, PAD was independently negatively related to TBiL and DBiL, with odds ratios (OR) 0.914 (95% confidence interval [CI]: 0.845-0.990) and 0.748 (95% CI: 0.572-0.977). In addition, there was a relationship between PAD and bilirubin levels (TBiL-OR = 0.884, 95% CI: 0.792-0.985; DBiL-OR = 0.621; 95% CI: 0.424-0.909) only in males but not in females. Future studies should further evaluate whether interventions that increase serum bilirubin levels will have a particular role in PAD prevention in males.

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.

Association of Lower Serum Bilirubin With Loss of Residual Kidney Function in Peritoneal Dialysis Patients

Bilirubin is recognized as an endogenous antioxidant, and low serum bilirubin is reported to be associated with the progression of kidney disease. However, it is unclear whether serum bilirubin levels are associated with the loss of residual kidney function (RKF) in peritoneal dialysis (PD) patients. This study investigated the relationship between serum total bilirubin and loss of RKF. We prospectively followed 94 PD patients who started PD in our hospital between June 2006 and May 2016. Ten patients who had chronic liver disease or cirrhosis were excluded. Patients were divided into three groups based on serum total bilirubin concentration tertiles: tertile 1 (T1) < 0.3, T2 = 0.3, and T3 ≥ 0.4 mg/dL. We estimated the relationship between serum bilirubin and loss of RKF, defined as daily urine volume (<100 mL) within 3 years after starting PD, using a Cox proportional hazards model. During the 3-year observation period, 22 patients lost RKF. The incidence rate of loss of RKF increased linearly with the decrease in serum total bilirubin levels (P for trend < 0.05). After adjusting for confounding factors, low serum total bilirubin level was shown to be an independent predictor of loss of RKF (hazard ratio [HR] for every 0.1 mg/dL decrease, 1.50; 95% confidence interval [CI], 1.01-2.51; HR [95%CI] for T2 and T1 [vs. T3] 2.03 [0.65-7.88] and 3.70 [1.00-15.9]). This study suggests that low serum total bilirubin levels are associated with the loss of RKF in PD patients.

Review of serum biomarkers in carotid atherosclerosis

BACKGROUND

Carotid artery atherosclerotic stenosis is a preventable major cause of stroke, but there is still a need for definition of high-risk plaque in asymptomatic patients who might benefit from interventional therapies. Several image markers are recommended to characterize unstable plaques. The measurement of serum biomarkers is a promising method to assist in decision making, but the lack of robust evidence in the carotid environment burdens their potential as a standard of care. The goal of this review was to offer an updated state-of-the-art study of available serum biomarkers with clinical implications, with focus on those that may predict carotid symptom development.

METHODS

The Cochrane Library and MEDLINE databases were searched (all until September 2018) for studies on carotid plaque and serum biomarkers of atherosclerosis. Nonhuman, basic science, and histology studies were excluded, focusing on clinical studies. Selected abstracts were screened to include the most relevant articles on atherosclerotic plaque presence, progression, instability or symptom development.

RESULTS

Some well-established biomarkers for coronary disease are not relevant to carotid atherosclerosis and other inflammatory biomarkers, lipids, interleukins, homocysteine, and adipokines may be useful in quantifying carotid disease-related risk. Some serum biomarkers combined with image features may assist vascular specialists in selecting patients at high risk for stroke and in need of intervention.

CONCLUSIONS

Prospective studies applying a combination of biomarkers are essential to prove clinical usefulness.

Association of circulating total bilirubin level with ischemic stroke: a systemic review and meta-analysis of observational evidence

Background

Circulating total bilirubin is a biomarker of ischemic stroke and may serve as a potential prognostic factor. It is imperative to systemically evaluate the correlation between circulating total bilirubin and risk for stroke. This systematic review and meta-analysis investigated the relationship between total serum bilirubin and risk for stroke.

Methods

Studies published before 30 June 2017 were searched in four databases (PubMed, EMBASE, Web of Science and Cochrane Central). Additional studies were searched by reviewing references and contacting authors. Cohort, cross-sectional and case-control studies in adults that examined the association between serum total bilirubin and stroke were included irrespective of language and date of publication. The primary outcome of this study was ischemic stroke, and the secondary outcome was stroke. Abstract and full-text were reviewed by two independent reviewers, and disagreement was resolved by consulting a third reviewer. Data were extracted by two independent reviewers using a pre-designed data collection form.

Results

Eleven observational studies (5 prospective and 6 cross-sectional studies) involving 131,450 subjects were included for analysis. In four studies with 83,380 subjects, the relationship between circulating total bilirubin and ischemic stroke was investigated, ischemic stroke was found in 2,496 patients, and the total odds ratio (OR) of the highest bilirubin and the lowest bilirubin for the occurrence of ischemic stroke was 0.66 (95% CI: 0.58-0.74). Eleven studies with 131,450 subjects explored the correlation between bilirubin and stroke, stroke was reported in 5,060 patients, and the total OR of the highest bilirubin and the lowest bilirubin for the occurrence of stroke was 0.73 (95% CI: 0.68-0.79). A stratified analysis based on the gender showed that the total bilirubin level in males correlated with ischemic stroke or stroke, which was not noted in females.

Conclusions

The available studies support an inverse association between circulating total bilirubin and risk for ischemic stroke and stroke in males. Prospective studies with large sample size are needed to establish the role of circulating bilirubin in the prevention of stroke.

Determination of the Predictive Value of Serum Bilirubin in Patients with Ischemic Stroke: A Prospective Descriptive Analytical Study

Purpose: In all types of ischemic stroke, especially in the acute phase, excessive oxidative stress causes structural and functional damage to the brain. This may play a major role in the pathophysiology of the brain damage. Higher serum levels of bilirubin have therapeutic effects in oxidative stress-induced stroke. Nevertheless, role of increased serum levels of bilirubin in the acute phase of ischemic stroke is ccontroversial.

Methods: This study was a cross-sectional prospective descriptive study conducted in the Emergency Department (ED) of Imam Reza hospital, Tabriz University of Medical Sciences, Tabriz, Iran, throughout six months. 275 ischemic stroke patients were evaluated based on their brain CT scan infarct size, NIHSS, MRS, and serum levels of bilirubin. Later, data were analyzed using SPSS software.

Results: Results: Total, direct and indirect bilirubin levels were significantly higher in expired patients (p < 0.0001). Total (p< 0.0001), direct (p< 0.0001) and indirect (p< 0.0001) bilirubin levels, NIHSS score (p< 0.0001), and ischemic area (p< 0.0001) significantly predicted the outcome in these patients.

Conclusion: Total, direct and indirect bilirubin levels was significantly associated with mortality in the acute phase of ischemic stroke patients.

Exploring the relationship of peripheral total bilirubin, red blood cell, and hemoglobin with blood pressure during childhood and adolescence

OBJECTIVE

Total bilirubin is beneficial for protecting cardiovascular diseases in adults. The authors aimed to investigate the association of total bilirubin, red blood cell, and hemoglobin levels with the prevalence of high blood pressure in children and adolescents.

METHODS

A total of 3776 students (aged from 6 to 16 years old) were examined using cluster sampling. Pre-high blood pressure and high blood pressure were respectively defined as the point of 90th and 95th percentiles based on the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents. Both systolic and diastolic blood pressure were standardized into z-scores.

RESULTS

Peripheral total bilirubin, red blood cell and hemoglobin levels were significantly correlated with age, and also varied with gender. Peripheral total bilirubin was negatively correlated with systolic blood pressure in 6- and 9-year-old boys, whilst positively correlated with diastolic blood pressure in the 12-year-old boys and 13- to 15-year-old girls (p<0.05). Higher levels of red blood cell and hemoglobin were observed in pre-high blood pressure and high blood pressure students when compared with their normotensive peers (p<0.01). The increases in red blood cell and hemoglobin were significantly associated with high blood pressure after adjusting for confounding factors. The ORs (95% CI) of each of the increases were 2.44 (1.52-3.92) and 1.04 (1.03-1.06), respectively. No statistical association between total bilirubin and high blood pressure was observed (p>0.05).

CONCLUSION

Total bilirubin could be weakly correlated with both systolic and diastolic blood pressure, as correlations varied with age and gender in children and adolescents; in turn, the increased levels of red blood cell and hemoglobin are proposed to be positively associated with the prevalence of high blood pressure.

Serum total bilirubin concentration in patients with type 2 diabetes as a possible biomarker of polyvascular disease

AIMS

The aim of this study was to investigate the association between serum total bilirubin concentration and complicated macrovascular diseases, such as cerebrovascular disease (CBVD), cardiovascular disease (CAD), and peripheral arterial disease (PAD), in patients with type 2 diabetes.

METHODS

We performed a retrospective cross-sectional study in 674 patients with type 2 diabetes. Serum total bilirubin concentration was compared between patients with and without CBVD, CAD, and PAD. Logistic regression analyses were performed to identify risk factors for CBVD, CAD, and PAD. Associations between total bilirubin concentration and the number of complicated macrovascular diseases were analyzed.

RESULTS

Patients with CBVD and PAD showed significantly lower serum total bilirubin concentrations than did those patients without those diseases. However, the bilirubin concentration did not differ between patients with and without CAD. Total bilirubin concentration was an independent predictor of CBVD, but not of CAD or PAD. There was a statistically significant trend for a decrease in bilirubin concentration in the presence of an increasing number of macrovascular diseases.

CONCLUSION

The presence of more than one macrovascular disease, called polyvascular disease, carries a high risk for cardiovascular mortality. Serum total bilirubin concentration may be useful as a clinical biomarker of polyvascular disease.

Pitfalls in the ankle-brachial index and brachial-ankle pulse wave velocity

Background

The ankle-brachial index (ABI) and pulse wave velocity (PWV) are indices of atherosclerosis and arterial stiffness. The Japan-made measuring devices of those indices have spread widely because of their convenience and the significance of the parameters. However, studies that comprehensively discuss the various pitfalls in using these indices are not available.

Methods

This study presents several representative pitfalls in using the ABI and brachial-ankle PWV (baPWV) by showing the result sheets of the device, “the Vascular Profiler”. Furthermore, some considerations when utilizing these indices in the future are also discussed.

Results

Several diseases such as arteriosclerosis obliterans (ASO), arterial calcification in the lower limb, arterial stenosis in the right upper-limb, aortic valve diseases, arterial stenosis in the upper-limb of the contralateral side of the hemodialysis access, are the representative pitfalls when evaluating ABI and baPWV. Moreover, a measurement error is found to actually exist. Furthermore, same phenomena are considered most likely to occur when using other similar indices and devices.

Conclusion

The ABI and baPWV are the useful and significant biomarkers. Nevertheless, caution is sometimes necessary when interpreting them. Moreover, rigorous patient exclusion criteria should be considered when using those indices in the severely conditioned patient population. And the results of this study can be applied to enhance the literacy using other indices, such as the cardio-ankle vascular index and other similar devices.

Evaluation of genetic effect of NOS3 and G×E interaction on the variability of serum bilirubin in a Han Chinese population

Bilirubin was shown to be related to the generation and functional exertion of endothelial nitric oxide synthase (eNOS) whilst the genetic effect of NOS3 on bilirubin variability was rarely reported. Herein we assessed the associations of three single nucleotide polymorphisms (SNPs) of NOS3 (rs4496877, rs1808593, and rs3918186) with bilirubin elevation in 2077 adults. The results showed that rs1808593 was significantly associated with bilirubin elevation, and odds ratios (ORs) of dominant model for the elevation of total bilirubin (TBIL), direct bilirubin (DBIL), and indirect bilirubin (IDBIL) were 0.837, 0.821 and 0.754, respectively (P < 0.05 for all). Stratification analysis indicated that rs3918186 was significantly associated with the elevation of TBIL and IDBIL in the males, and ORs of dominant model were 1.505 and 1.440 with P < 0.05 for all. In the smoking group, significant associations of rs4496877, rs1808593, and rs3918186 with TBIL elevation were observed, and ORs of dominant model were 1.739, 0.758 and 1.626 (P < 0.05 for all). rs4496877 and rs3918186 were both associated with TBIL elevation in the drinking group, and ORs were 1.557 and 1.769 with P < 0.05 for all. In the ≥55 year-old group, rs4496877 and rs1808593 were significantly associated with DBIL and IDBIL elevations, and ORs were 1.340 and 0.790 (P < 0.05). Meanwhile, rs4496877, rs1808593, rs3918186, smoking, and drinking were shown to have a notable interaction effects on the TBIL elevation. Our findings supported that NOS3 harbors the genetic susceptibility to the bilirubin elevation. Age, gender, smoking, and drinking could be involved in the genetic modification of NOS3 on the bilirubin variability.

The molecular basis of jaundice: An old symptom revisited

Increased serum bilirubin level is a widely used diagnostic marker for hepatic illnesses. Nevertheless, mild elevation of unconjugated serum bilirubin (such as in Gilbert syndrome) has been recently demonstrated to correlate with low risk of chronic inflammatory and/or oxidative stress-mediated diseases. In accord, a low serum bilirubin level has emerged as an important predisposing factor or a biomarker of these pathologic conditions including cardiovascular, tumour, and possibly neurodegenerative diseases. Bilirubin possesses multiple biological actions with interaction in a complex network of enzymatic and signalling pathways. The fact that the liver is the main organ controlling the bioavailability of bilirubin emphasizes the central role of this organ in human health.

Differential impact of serum total bilirubin level on cerebral atherosclerosis and cerebral small vessel disease

BACKGROUND

A low serum total bilirubin (T-bil) level is associated with an increased risk of atherosclerosis. However, the differential impact of the serum T-bil level on cerebral atherosclerosis and cerebral small vessel disease (SVD) is still unclear.

METHODS

We evaluated serum T-bil levels from 1,128 neurologically healthy subjects. Indices of cerebral atherosclerosis (extracranial arterial stenosis [ECAS] and intracranial arterial stenosis [ICAS]), and indices of SVD (silent lacunar infarct [SLI], and moderate-to-severe white matter hyperintensities [msWMH]) were evaluated by the use of brain magnetic resonance imaging (MRI) and MR angiography.

RESULTS

In logistic regression analysis after adjusting for confounding variables, subjects within middle T-bil (odds ratio [OR]: 0.63; 95% CI: 0.41-0.97) and high T-bil tertiles (OR: 0.54; 95% CI: 0.33-0.86) showed a lower prevalence of ECAS than those in a low T-bil tertile. Although subjects with a high T-bil tertile had a lower prevalence of ICAS than those with a low T-bil tertile, the statistical significance was marginal after adjusting for confounding variables. There were no significant differences in the proportions of subjects with SLI and msWMH across serum T-bil tertile groups.

CONCLUSIONS

The serum T-bil level is negatively associated with cerebral atherosclerosis, especially extracranial atherosclerosis, but not with SVD.

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.

Higher Level of Serum Heme Oxygenase-1 in Patients With Intracerebral Hemorrhage

The objective of this paper was to investigate the association of the serum level of heme oxygenase-1 in patients with intracerebral hemorrhage (ICH) with the risk of ICH. Heme oxygenase-1(HO-1) metabolizes heme into biliverdin, bilirubin, carbon monoxide, and iron, our recent study showed that serum level of HO-1 was increased in stroke patients, yet the association of HO-1 level with risk of intracerebral hemorrhage (ICH) is poorly known. Forty patients with ICH and another 40 patients without ICH were recruited. The serum level of HO-1, total, and direct bilirubin were measured. The level of HO-1, serum total bilirubin, and direct bilirubin, as well as blood pressure were increased in ICH group than in control group (P < 0.001). The level of HO-1, both systolic and diastolic blood pressure had a significant difference between subgroups (P < 0.05). Multivariate regression analysis showed that poor compliance to medicine for hypertension, the serum level of HO-1, and systolic blood pressure were associated with the prevalence of ICH. Blood pressure, serum HO-1, serum total bilirubin, and direct bilirubin were raised in patients with ICH who did not take medicine for hypertension compared with those who did, and increased in ICH patients in comparison with control group. Further investigation in multiple medical centers with large number of cohorts is warranted to verify these results.

Bilirubin exerts pro-angiogenic property through Akt-eNOS-dependent pathway

Low serum bilirubin levels are associated with the risk of cardiovascular diseases including peripheral artery disease. Bilirubin is known to exert its property such as antioxidant effect or the enhancement of flow-mediated vasodilation, however, bilirubin action on angiogenesis remains unclear. To investigate the molecular mechanism of bilirubin on angiogenic effect, we first employed C57BL/6J mice with unilateral hindlimb ischemia surgery and divided the mice into two groups (vehicle-treated group and bilirubin-treated group). The analysis of laser speckle blood flow demonstrated the enhancement of blood flow recovery in response to ischemia of mice with bilirubin treatment. The density of capillaries was significantly higher in ischemic-adductor muscles of bilirubin-treated mice. The phosphorylated levels of endothelial nitric oxide synthase (eNOS) and Akt were increased in ischemic skeletal muscles of mice with bilirubin treatment compared with vehicle treatment. In in vitro experiments by using human aortic endothelial cells, bilirubin augmented eNOS and Akt phosphorylation, cell proliferation, cell migration and tube formation. These bilirubin actions on endothelial cell activation were inhibited by LY294002, a phosphatidylinositol 3-kinase inhibitor. In conclusion, bilirubin promotes angiogenesis through endothelial cells activation via Akt-eNOS-dependent manner.

Association between whole blood viscosity and arterial stiffness in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (DM) carries an increased risk for cardiovascular complications. The brachial-ankle pulse wave velocity (baPWV) is an index for early atherosclerotic changes. Recently, the effect of altered blood rheology on atherosclerosis has received attention. Therefore, this study aimed to examine the association of hemorheological parameters with baPWV in patients with DM. In this cross-sectional study, we investigated the relationship between rheological parameters and baPWV in 323 control subjects (160 men and 163 women) and 382 patients with DM (170 men and 212 women). The participants with DM had higher whole blood viscosity (WBV) levels both at low shear rate (3 s(-1)) and at high shear rate (200 s(-1)) than those without DM. Different metabolic parameters were compared across WBV (3 s(-1)) quartiles. The mean values of baPWV gradually increased with WBV (3 s(-1)) quartiles. In addition, there was a positive correlation between baPWV and WBV 3 s(-1) in patients with DM after adjusting confounding factors (r = 0.285, p = 0.039). Stepwise multiple linear regression analysis further revealed that WBV (3 s(-1)) is a significant determinant for increased baPWV in DM (β = 0.184; p < 0.001). However, there were no association between WBV (3 s(-1)) and baPWV in control subjects. The findings showed that baPWV increased as WBV (3 s(-1)) elevated in DM. Moreover, WBV (3 s(-1)) is independently associated with baPWV even after adjusting other cardiovascular risk factors. Early detection of abnormal WBV levels at low shear rate should warrant for early search of undetected arterial stiffness in patients with DM.

NADPH Oxidase Activity in Cerebral Arterioles Is a Key Mediator of Cerebral Small Vessel Disease-Implications for Prevention

Cerebral small vessel disease (SVD), a common feature of brain aging, is characterized by lacunar infarcts, microbleeds, leukoaraiosis, and a leaky blood-brain barrier. Functionally, it is associated with cognitive decline, dementia, depression, gait abnormalities, and increased risk for stroke. Cerebral arterioles in this syndrome tend to hypertrophy and lose their capacity for adaptive vasodilation. Rodent studies strongly suggest that activation of Nox2-dependent NADPH oxidase activity is a crucial driver of these structural and functional derangements of cerebral arterioles, in part owing to impairment of endothelial nitric oxide synthase (eNOS) activity. This oxidative stress may also contribute to the breakdown of the blood-brain barrier seen in SVD. Hypertension, aging, metabolic syndrome, smoking, hyperglycemia, and elevated homocysteine may promote activation of NADPH oxidase in cerebral arterioles. Inhibition of NADPH oxidase with phycocyanobilin from spirulina, as well as high-dose statin therapy, may have potential for prevention and control of SVD, and high-potassium diets merit study in this regard. Measures which support effective eNOS activity in other ways-exercise training, supplemental citrulline, certain dietary flavonoids (as in cocoa and green tea), and capsaicin, may also improve the function of cerebral arterioles. Asian epidemiology suggests that increased protein intakes may decrease risk for SVD; conceivably, arginine and/or cysteine-which boosts tissue glutathione synthesis, and can be administered as N-acetylcysteine-mediate this benefit. Ameliorating the risk factors for SVD-including hypertension, metabolic syndrome, hyperglycemia, smoking, and elevated homocysteine-also may help to prevent and control this syndrome, although few clinical trials have addressed this issue to date.

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.

Circulating Total Bilirubin and Risk of Incident Cardiovascular Disease in the General Population

Objective—

To assess the association of circulating total bilirubin and cardiovascular disease (CVD) risk in a new prospective study and to determine whether adding information on total bilirubin values to established cardiovascular risk factors is associated with improvement in prediction of CVD risk.

Approach and Results—

Circulating total bilirubin levels were measured at baseline in the PREVEND (Prevention of Renal and Vascular End-stage Disease) prospective study of 7222 participants and 773 incident CVD events. Total bilirubin was log-linearly associated with CVD risk. Age- and sex-adjusted hazard ratio (95% confidence interval) for CVD per 1-SD increase in log e total bilirubin was 0.82 (0.76 to 0.88; P <0.001), which was minimally attenuated to 0.89 (0.82 to 0.96; P =0.003) after further adjustment for established risk factors. In a meta-analysis of 12 population-based prospective studies involving 9378 incident CVD cases, the pooled multivariate-adjusted relative risk (95% confidence interval) for CVD was 0.93 (0.90 to 0.97; P <0.001) per 1-SD increase in total bilirubin levels. The corresponding pooled risks for coronary heart disease and stroke were 0.95 (0.92 to 0.99; P =0.018) and 0.93 (0.88 to 0.98; P =0.006), respectively. Addition of information on total bilirubin to a CVD risk prediction model containing established risk factors was associated with a C-index change of 0.0013 (−0.0004 to 0.0029; P =0.13).

Conclusions—

There is a log-linear inverse association between circulating total bilirubin level and CVD risk, which is independent of established risk factors. Nonetheless, inclusion of total bilirubin in the standard established risk factors panel provides no significant improvement in CVD risk prediction.

Non-alcoholic fatty liver disease is associated with progression of arterial stiffness

BACKGROUND AND AIMS

NAFLD is an independent risk factor for increased cardiovascular disease. Arterial stiffness is an index of subclinical atherosclerosis. The aims of this study were to examine prospectively the relationship between Non-alcoholic fatty liver disease (NAFLD) and the progression of arterial stiffness.

METHODS AND RESULTS

A prospective study of 728 men and 497 women free of hypertension, and diabetes at the baseline were conducted. The subjects were followed for 5 years. The progression rate of arterial stiffness was measured by calculating the increase in brachial-ankle pulse wave velocity (baPWV) the changes of the baPWV (adjusted for age) during the study period was significantly greater in the patients with NAFLD (172.4 ± 42.1 cm/s for men, 95.8 ± 36.7 cm/s for women) than in the subjects without NAFLD (70.3 ± 56.5 cm/s for men, 55.4 ± 42.2 cm/s for women). For the subjects with metabolic syndrome, after adjusting for multiple risk factors, NAFLD was a significant predictor of baPWV progression (for male, β = 0.843; P < 0.001; for female, β = 0.575; P < 0.001, respectively). In addition, results were unmodified in subjects without metabolic syndrome.

CONCLUSIONS

NAFLD was found to be an independent predictor of faster progression of baPWV even after adjusting other cardiovascular risk factors. These prospective data support a pathogenic role for NAFLD in the development of arterial stiffness.

Association between whole blood viscosity and arterial stiffness in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (DM) carries an increased risk for cardiovascular complications. The brachial-ankle pulse wave velocity (baPWV) is an index for early atherosclerotic changes. Recently, the effect of altered blood rheology on atherosclerosis has received attention. Therefore, this study aimed to examine the association of hemorheological parameters with baPWV in patients with DM. In this cross-sectional study, we investigated the relationship between rheological parameters and baPWV in 323 control subjects (160 men and 163 women) and 382 patients with DM (170 men and 212 women). The participants with DM had higher whole blood viscosity (WBV) levels both at low shear rate (3 s(-1)) and at high shear rate (200 s(-1)) than those without DM. Different metabolic parameters were compared across WBV (3 s(-1)) quartiles. The mean values of baPWV gradually increased with WBV (3 s(-1)) quartiles. In addition, there was a positive correlation between baPWV and WBV 3 s(-1) in patients with DM after adjusting confounding factors (r = 0.285, p = 0.039). Stepwise multiple linear regression analysis further revealed that WBV (3 s(-1)) is a significant determinant for increased baPWV in DM (β = 0.184; p < 0.001). However, there were no association between WBV (3 s(-1)) and baPWV in control subjects. The findings showed that baPWV increased as WBV (3 s(-1)) elevated in DM. Moreover, WBV (3 s(-1)) is independently associated with baPWV even after adjusting other cardiovascular risk factors. Early detection of abnormal WBV levels at low shear rate should warrant for early search of undetected arterial stiffness in patients with DM.

Higher level of heme oxygenase-1 in patients with stroke than TIA

BACKGROUND

There is a reverse relationship between serum bilirubin level and incidence of stroke, heme oxygenase-1 (HO-1) can catalyze heme into bilirubin, it is unknown the association of HO-1 level with risk of stroke.

METHODS

Sixty patients with stroke and fifty patients with transient ischemic attack (TIA) were recruited. Serum level of HO-1, total and direct bilirubin, alanine transaminase, live function, lipid profile and infection status of patients were measured.

RESULTS

Significant differences were found between two groups in terms of serum levels of HO-1 (163.6±58.7 vs. 141.2±49.7, P=0.032), total bilirubin (10.1±4.6 vs. 15.8±2.7, P<0.001), direct bilirubin (3.2±2.1 vs. 5.9±1.2, P<0.001), fasting glucose (6.7±3.1 vs. 4.9±1.3, P<0.001), cholesterol (4.4±1.1 vs. 3.9±0.8, P=0.005) and diastolic blood pressure (DBP) (84.9±9.4 vs. 81.3±9.2, P=0.046). In multivariate analysis, serum direct bilirubin (OR, 2.83; P<0.001), total bilirubin (OR, 1.82, P=0.001), DBP (OR, 0.88, P=0.041), and fasting glucose (OR, 0.34, P<0.001) were independent predictors of stroke.

CONCLUSIONS

Serum HO-1 level is higher in patients with stroke than TIA, but the bilirubin level is lower in patients with stroke than TIA and is an independent predictor of stroke. Further studies are warranted to clarify the underlying link among HO-1, bilirubin and stroke.

Higher level of heme oxygenase-1 in patients with stroke than TIA

BACKGROUND

There is a reverse relationship between serum bilirubin level and incidence of stroke, heme oxygenase-1 (HO-1) can catalyze heme into bilirubin, it is unknown the association of HO-1 level with risk of stroke.

METHODS

Sixty patients with stroke and fifty patients with transient ischemic attack (TIA) were recruited. Serum level of HO-1, total and direct bilirubin, alanine transaminase, live function, lipid profile and infection status of patients were measured.

RESULTS

Significant differences were found between two groups in terms of serum levels of HO-1 (163.6±58.7 vs. 141.2±49.7, P=0.032), total bilirubin (10.1±4.6 vs. 15.8±2.7, P<0.001), direct bilirubin (3.2±2.1 vs. 5.9±1.2, P<0.001), fasting glucose (6.7±3.1 vs. 4.9±1.3, P<0.001), cholesterol (4.4±1.1 vs. 3.9±0.8, P=0.005) and diastolic blood pressure (DBP) (84.9±9.4 vs. 81.3±9.2, P=0.046). In multivariate analysis, serum direct bilirubin (OR, 2.83; P<0.001), total bilirubin (OR, 1.82, P=0.001), DBP (OR, 0.88, P=0.041), and fasting glucose (OR, 0.34, P<0.001) were independent predictors of stroke.

CONCLUSIONS

Serum HO-1 level is higher in patients with stroke than TIA, but the bilirubin level is lower in patients with stroke than TIA and is an independent predictor of stroke. Further studies are warranted to clarify the underlying link among HO-1, bilirubin and stroke.