Association of serum bilirubin and uric acid levels changes during neuroinflammation in patients with initial and relapsed demyelination attacks

Neuroprotective Roles of the Biliverdin Reductase-A/Bilirubin Axis in the Brain

Biliverdin reductase-A (BVRA) is a multi-functional enzyme with a multitude of important roles in physiologic redox homeostasis. Classically, BVRA is well known for converting the heme metabolite biliverdin to bilirubin, which is a potent antioxidant in both the periphery and the brain. However, BVRA additionally participates in many neuroprotective signaling cascades in the brain that preserve cognition. Here, we review the neuroprotective roles of BVRA and bilirubin in the brain, which together constitute a BVRA/bilirubin axis that influences healthy aging and cognitive function.

Bilirubin and Redox Stress in Age-Related Brain Diseases

Cellular redox status has a crucial role in brain physiology, as well as in pathologic conditions. Physiologic senescence, by dysregulating cellular redox homeostasis and decreasing antioxidant defenses, enhances the central nervous system's susceptibility to diseases. The reduction of free radical accumulation through lifestyle changes, and the supplementation of antioxidants as a prophylactic and therapeutic approach to increase brain health, are strongly suggested. Bilirubin is a powerful endogenous antioxidant, with more and more recognized roles as a biomarker of disease resistance, a predictor of all-cause mortality, and a molecule that may promote health in adults. The alteration of the expression and activity of the enzymes involved in bilirubin production, as well as an altered blood bilirubin level, are often reported in neurologic conditions and neurodegenerative diseases (together denoted NCDs) in aging. These changes may predict or contribute both positively and negatively to the diseases. Understanding the role of bilirubin in the onset and progression of NCDs will be functional to consider the benefits vs. the drawbacks and to hypothesize the best strategies for its manipulation for therapeutic purposes.

Effects of bilirubin on the development and electrical activity of neural circuits

In the past several decades, bilirubin has attracted great attention for central nervous system (CNS) toxicity in some pathological conditions with severely elevated bilirubin levels. CNS function relies on the structural and functional integrity of neural circuits, which are large and complex electrochemical networks. Neural circuits develop from the proliferation and differentiation of neural stem cells, followed by dendritic and axonal arborization, myelination, and synapse formation. The circuits are immature, but robustly developing, during the neonatal period. It is at the same time that physiological or pathological jaundice occurs. The present review comprehensively discusses the effects of bilirubin on the development and electrical activity of neural circuits to provide a systematic understanding of the underlying mechanisms of bilirubin-induced acute neurotoxicity and chronic neurodevelopmental disorders.

Evaluation of simple antioxidant blood parameters in patients with migraine

Background

The study aims to investigate the role of serum albumin (ALB) and creatinine (CRE), bilirubin (BIL), and uric acid (UA) as major intravascular antioxidants in migraine.

Methods

We enrolled 148 patients with migraine and 150 age- and sex-matched healthy controls. The serum levels of ALB, TBIL, CRE, and UA were measured in patients with migraine of different subtypes. The risk of migraine was assessed by multiple stepwise logistic regression analysis.

Results

The serum levels of ALB, total BIL (TBIL), CRE, and UA were significantly lower in the migraine group than in the HC group (p < 0.05). The ALB and UA levels were lower during migraine attack periods (p < 0.05). There were no statistically significant differences observed in serum ALB, TBIL, CRE, and UA levels between aura/without aura and episodic/chronic migraine subtypes (p > 0.05). The multiple stepwise logistic regression revealed that ALB [odds ratio (OR) 0.79, 95% confidence interval (CI) 0.69–0.89, p < 0.001], TBIL (OR 0.61, 95% CI 0.5–0.75, p < 0.001), and UA (OR 0.97, 95% CI 0.96–0.99, p = 0.014) were independently associated with migraine. In addition, the serum levels of ALB, TBIL, and UA were significantly lower in the migraine group when compared by sex.

Conclusion

The serum levels of UA, TBIL, ALB, and CRE were lower in the patients with migraine, indicating a lower antioxidant status. In addition, ALB, TBIL, and UA were independently related to migraine. These results could provide insights into the possible role of oxidative stress in the pathogenesis of migraine.

Hyperuricemia and hypertriglyceridemia indicate tubular atrophy/interstitial fibrosis in patients with IgA nephropathy and membranous nephropathy

PURPOSE

Hyperuricemia (HUA) and hypertriglyceridemia (HTG) were very common in chronic kidney disease (CKD) and associated with accelerated progression of CKD. This was a retrospective, cross-sectional study which aimed to explore the relationship between serum uric acid levels or triglyceride levels and tubular atrophy/interstitial fibrosis (proven by renal biopsy).

METHODS

The present study enrolled 229 CKD individuals who included 127 biopsy-proven primary IgA nephrology (IgAN) patients and 102 biopsy-proven primary membranous nephropathy (MN) patients. The baseline characteristics at the time of the kidney biopsy were collected. According to the serum uric acid (UA) or triglyceride (TG) whether it exceeds the normal reference range, patients were divided into non-HUA (n = 127), HUA (n = 102), non-HTG (n = 119), and HTG group (n = 110). Based on the extent of tubular atrophy/interstitial fibrosis, patients were divided into no/mild injury (T0, n = 127), moderate injury (T1, n = 102). Multivariable logistic regression for factors predicting moderate tubular atrophy/interstitial fibrosis was performed.

RESULTS

There were 127 IgAN and 102 MN cases among 229 patients in the present study. The prevalence of HUA was 44.5% (n = 102), 40.9% (n = 52), and 49.0% (n = 50) in all patients, IgAN patients and MN patients, respectively (P = 1.49). The prevalence of HTG was 48.0% (n = 110), 29.9% (n = 38), and 70.6% (n = 72) (P < 0.001), respectively, as well. Multivariate logistic regression analysis showed that HUA and HTG were independent risk factors for moderate tubular atrophy/interstitial fibrosis (HUA OR = 2.335, 95% CI = 1.147-4.755, P = 0.019; HTG OR = 2.646, 95% CI = 1.289-5.432, P = 0.008). The area under curve (AUC) of model 1 (HUA + eGFR + HTG + age + serum globulin + 24 h urinary protein, AUC = 0.876) was larger than the other two models; however, there was no significant difference among these models (all P > 0.05).

CONCLUSIONS

Hyperuricemia and hypertriglyceridemia, which were prevalent in CKD patients, were the independent risk factors for moderate tubular atrophy/interstitial fibrosis. HUA together with HTG could improve the value of diagnosis for moderate tubular atrophy/interstitial fibrosis to some extent.

The Impact of Multiple Sclerosis Disease Status and Subtype on Hematological Profile

Multiple sclerosis (MS) is an immune-mediated, demyelinating disease of the central nervous system. In this study, an MS cohort and healthy controls were stratified into Caucasian and African American groups. Patient hematological profiles-composed of complete blood count (CBC) and complete metabolic panel (CMP) test values-were analyzed to identify differences between MS cases and controls and between patients with different MS subtypes. Additionally, random forest models were used to determine the aggregate utility of common hematological tests in determining MS disease status and subtype. The most significant and relevant results were increased bilirubin and creatinine in MS cases. The random forest models achieved some success in differentiating between MS cases and controls (AUC values: 0.725 and 0.710, respectively) but were not successful in differentiating between subtypes. However, larger samples that adjust for possible confounding variables, such as treatment status, may reveal the value of these tests in differentiating between MS subtypes.

Low Antioxidant Status of Serum Uric Acid, Bilirubin, Albumin, and Creatinine in Patients With Benign Paroxysmal Positional Vertigo

Objective: To investigate the roles of serum uric acid (UA), bilirubin (BIL), albumin (ALB), and creatinine (CRE) as major intravascular antioxidants, in benign paroxysmal positional vertigo (BPPV).

Methods: The serum levels of UA, BIL, ALB, and CRE were retrospectively analyzed in 70 patients with new-onset idiopathic BPPV and 140 age- and sex-matched healthy controls (HCs).

Results: Serum UA, BIL, ALB, and CRE levels were significantly lower in the BPPV group than the HC group. Furthermore, serum levels of BIL and ALB were significantly lower in the BPPV group when compared by sex. Multiple stepwise logistic regression revealed that a reduction in serum ALB was independently related to BPPV (odds ratio = 0.688; 95% confidence interval = 0.607– 0.780). Receiver operating characteristic analyses revealed a cut-off value of 45.15 g/L for ALB with a sensitivity of 74.29% (62.97– 83.07%) and specificity of 73.57% (65.71– 80.18%).

Conclusions: Serum levels of UA, BIL, ALB, and CRE were lower in BPPV patients, indicating a lower antioxidant status. Furthermore, a reduction in serum ALB was independently associated with BPPV. These results provide insights into the possible roles of oxidative stress in the pathogenesis of BPPV.

Relationship between serum bilirubin levels s and the progression of renal function in patients with chronic kidney disease and hyperuricemia

It is known that inflammation and oxidative stress have strong influences on chronic kidney disease (CKD). As an antioxidant, bilirubin is currently under extensive scrutiny. However, there are disagreements with regard to the oxidative and antioxidative roles of serum uric acid (SUA). This study aimed to investigate the relationship between serum bilirubin and the progression of renal function in CKD patients with hyperuricemia (HUA). This retrospective longitudinal study included 427 CKD patients. The endpoint was renal replacement therapy or death. Patients were divided into the following two groups according to the SUA level: HUA group (SUA ≥ 420 μmol/L for men; SUA ≥ 360 μmol/L for women) and normal uric acid level (NUA) group. A Cox proportional hazards model was used to evaluate the risk factors for renal outcomes in the two patient groups. The median follow-up time was 36 months. In the Cox regression analysis, the risk of renal outcomes in patients with serum indirect bilirubin (IBIL) levels >4.55 μmol/L was 0.15 times the risk in patients with serum IBIL levels ≤4.55 μmol/L (hazard ratio = 0.15, p = .013). Our findings suggest that a high serum IBIL level might be a protective factor for the progression of renal function in CKD patients with HUA.

Serum Bilirubin and Albumin in Anti-N-Methyl-D-Aspartate Receptor Encephalitis

BACKGROUND AND OBJECTIVE

Low serum levels of bilirubin and albumin are associated with multiple autoimmune diseases, but their role in anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is unknown.

METHODS

Serum bilirubin and albumin levels were evaluated in 60 patients with anti-NMDAR encephalitis, 50 cryptococcal encephalitis, and 145 healthy controls (CTLs). Of the 60 anti-NMDAR encephalitis patients, 30 had a follow-up evaluation at 3 months after admission.

RESULTS

Serum bilirubin and albumin levels were both significantly lower in anti-NMDAR encephalitis than in CTLs, and serum bilirubin levels were significantly lower in anti-NMDAR encephalitis than in cryptococcal encephalitis. Serum bilirubin levels were significantly lower in patients with psychiatric symptoms, with severe impairment, and with limited responses to treatment than those without psychiatric symptoms, with mild impairment, and with favorable responses to treatment, respectively. A follow-up evaluation of 30 patients revealed that the modified Rankin Scale scores were significantly decreased after treatment. Serum bilirubin significantly associated with serum albumin, and plasma hemoglobin.

CONCLUSIONS

Our results revealed for the first time an association between the serum levels of bilirubin in the anti-NMDAR encephalitis. Further studies investigating the role of bilirubin and albumin in anti-NMDAR encephalitis are required.

Is serum bilirubin associated with the severity of Guillain-Barré syndrome?

OBJECTIVE

Our aim was to assess the correlation between serum bilirubin levels and Guillain-Barré syndrome (GBS).

PATIENTS AND METHODS

One hundred and one newly diagnosed patients with Guillain-Barré syndrome and 111 healthy age- and sex-matched individuals in the First Affiliated Hospital of Guangxi Medical University (Guangxi, China) from June 2012 to May 2017 were included in this study. Clinical characteristics and laboratory parameters of Guillain-Barré syndrome patients and healthy controls were retrospectively analysed.

RESULTS

Serum bilirubin levels in Guillain-Barré syndrome patients were significantly lower as compared with those in healthy controls (p < 0.001); besides, log C-reactive protein and erythrocyte sedimentation rate were significantly higher. We found that there was a negative correlation between GBS disability scale scores and total bilirubin, direct bilirubin, indirect bilirubin (r = -0.541, P < 0.001; r = -0.403, P < 0.001; r = -0.526, P < 0.001), respectively. Among patients with GBS, serum total bilirubin, direct bilirubin, and indirect bilirubin levels were independently associated with Guillain-Barré syndrome disability scale scores in multiple linear regression analysis, respectively.

CONCLUSIONS

We observed that serum bilirubin levels were lower in patients with Guillain-Barré syndrome, and suggested total bilirubin, direct bilirubin, and indirect bilirubin were independently and inversely associated with Guillain-Barré syndrome severity.

Oxidative Stress and Environmental Exposures are Associated with Multiple System Atrophy in Chinese Patients

OBJECTIVE

Oxidative stress is involved in the pathogenesis of multiple system atrophy (MSA). The aim of this study is to examine oxidant biomarkers including homocysteine (Hcys), bilirubin, uric acid, lipids, and potential environmental risk factors and to ascertain whether these data correlate with MSA in a Chinese population.

METHODS

In this study, serum levels of Hcys, bilirubin, uric acid, and lipids were studied in 55 MSA patients and 76 healthy controls (HCs). Education, anti-parkinsonian agent usage, smoking, drinking, farming, and living area of the subjects also were analyzed. The Unified MSA Rating Scale (UMSARS), Hoehn & Yahr stage, International Cooperative Ataxia Rating Scale, and Mini-Mental State Examination were used to assess the disease severity, the parkinsonism, ataxia, and the cognitive ability of MSA, respectively.

RESULTS

The levels of Hcys were higher (p<0.001) and those of total bilirubin (p=0.007), indirect bilirubin (p=0.011), and total cholesterol (p=0.046) were lower in MSA patients than in healthy controls, whereas uric acid levels did not differ significantly between MSA and healthy controls. Moreover, Hcys levels in MSA patients had positive correlations with illness duration (r s =0.422, p=0.001) and UMSARS-I (r s =0.555, p<0.001), respectively. High-density lipoprotein cholesterol levels were negatively correlated with UMSARS-I (r s =-0.325, p=0.015). Farming was more frequent in MSA patients (1-20 years: odds ratio, 6.36; p20 years: odds ratio, 10.26; p=0.001), whereas current smoking was less frequent (odds ratio, 0.13, p=0.002).

CONCLUSIONS

Elevated Hcys and decreased high-density lipoprotein cholesterol may be associated with the disease severity of MSA. Environmental exposures such as farming and smoking may contribute to the occurrence but not the progression of MSA.

Low serum uric acid levels in patients with multiple sclerosis and neuromyelitis optica: An updated meta-analysis

OBJECTIVES

To evaluate the association between serum uric acid (UA) levels and patients with MS and NMO.

METHODS

The PubMed, Web of Science and Cochrane Library database were searched for relevant studies. Pooled standardized mean difference (SMD) and 95% confidence interval (CI) were used as effect size. Subgroup analysis was performed by gender, country, disease durations, scores of EDSS, detection method and clinical classification.

RESULTS

A total of 10 case-control studies involving 1537 patients (1308 MS patients, 229 NMO patients) and 908 healthy controls were included. We found the serum UA levels of patients with MS and NMO were significantly lower compared to those of healthy controls (SMD=-0.52, 95%CI,-0.81 to -0.24). In the subgroup analysis, there was no significant difference between serum UA levels in patients and healthy controls in European subgroup (SMD=-0.32, 95%CI,-0.78 to 0.14). Additionally, we found that serum UA levels were higher in MS and NMO patients than in healthy controls in EDSS>3.5 subgroup (SMD=-0.38, 95%CI,-0.58 to -0.19), but not in EDSS≤3.5 subgroup (SMD=-0.35, 95%CI,-0.97 to 0.27). Patients of relapsing group had significant lower serum UA levels than patients of remitting group (SMD=0.70, 95%CI, 0.19-1.21).

CONCLUSION

Patients with MS and NMO showed lower serum UA levels when compared with healthy controls. Serum UA might be a potential diagnostic biomarker for MS and NMO.

Uric acid: a potential biomarker of multiple sclerosis and of its disability

BACKGROUND

Uric acid (UA) is a strong natural scavenger of reactive oxygen and nitrogen species, with evidence of possible use in the treatment of animal models of multiple sclerosis (MS). Consequently, serum UA has gained much attention as a possible biomarker of MS. We aim to investigate differences in serum UA levels between MS subjects and controls and evaluate possible relationships of UA with MS clinical features.

METHODS

We recruited relapsing-remitting and secondary progressive MS subjects and healthy controls and measured their serum UA levels. We excluded subjects presenting concomitant conditions affecting UA levels.

RESULTS

MS subjects (n=362) and controls (n=181) were recruited by propensity score matching (PSM). Statistical analyses were corrected for age, gender, and renal function. MS subjects presented significantly lower serum UA levels than controls (analysis of variance, p=0.014, adjusted r2=0.3036). Linear regression analysis showed a relationship between UA levels and disease duration (p<0.001, adjusted r2=0.3158, coefficient -0.00039), time from diagnosis (p<0.001, adjusted r2=0.3100, coefficient -0.0012), and Expanded Disability Status Scale (EDSS) (p<0.001, adjusted r2=0.3230, coefficient -0.1).

CONCLUSIONS

Our findings support the importance of serum UA as a biomarker of MS disability and progression. Further studies with longitudinal design should be specifically designed to evaluate the importance of UA in the different stages of MS and in relation to distinct therapeutic strategies.

Relationship between serum uric acid and serum oxidative stress markers in the Japanese general population

BACKGROUND

Increased production of reactive oxygen species is a condition that is associated with, and plays a role in the progression of, various disorders such as hypertension, atherosclerosis, and diabetes.

PURPOSE

To assess in vivo oxidative stress levels and antioxidant potential and to analyze the relationship with serum uric acid (UA) levels.

METHODS AND RESULTS

Oxidative stress levels (derivatives of reactive oxygen metabolites, d-ROMs) and antioxidant potential (biological antioxidant potential, BAP) were measured in individuals who underwent a general health screening test, and data were analyzed from 8,025 individuals (2,953 women and 5,072 men) who were free from UA-lowering medication. Higher serum UA levels were associated with increased levels of d-ROMs in both genders, and this trend was more prominent in women. In addition, higher UA levels were also associated with higher BAP in both genders, although the dose dependence was not apparent in men. These associations remained statistically significant after adjusting for age, blood pressure, renal function, albuminuria, C-reactive protein, and insulin resistance index.

CONCLUSIONS

In individuals who underwent general health screening, serum UA levels were positively associated with both d-ROMs and BAP levels. Whether lowering of UA by lifestyle modification or by medication alters d-ROM/BAP levels awaits further investigations. .