Bilirubin as a metabolic hormone: the physiological relevance of low levels

Cardiac lipotoxicity and fibrosis underlie impaired contractility in a mouse model of metabolic dysfunction-associated steatotic liver disease

The leading cause of death among patients with metabolic dysfunction-associated steatotic liver disease (MASLD) is cardiovascular disease. A significant percentage of MASLD patients develop heart failure driven by functional and structural alterations in the heart. Previously, we observed cardiac dysfunction in hepatocyte-specific peroxisome proliferator-activated receptor alpha knockout (Ppara HepKO), a mouse model that exhibits hepatic steatosis independent of obesity and insulin resistance. The goal of the present study was to determine mechanisms that underlie hepatic steatosis-induced cardiac dysfunction in Ppara HepKO mice. Experiments were performed in 30-week-old Ppara HepKO and littermate control mice fed regular chow. We observed decreased cardiomyocyte contractility (0.17 ± 0.02 vs. 0.24 ± 0.02 μm, p < 0.05), increased cardiac triglyceride content (0.96 ± 0.13 vs. 0.68 ± 0.06 mM, p < 0.05), collagen type 1 (4.65 ± 0.25 vs. 0.31 ± 0.01 AU, p < 0.001), and collagen type 3 deposition (1.32 ± 0.46 vs. 0.05 ± 0.03 AU, p < 0.05). These changes were associated with increased apoptosis as indicated by terminal deoxynucleotidyl transferase dUTP nick end labeling staining (30.9 ± 4.7 vs. 13.1 ± 0.8%, p < 0.006) and western blots showing increased cleaved caspase-3 (0.27 ± 0.006 vs. 0.08 ± 0.01 AU, p < 0.003) and pro-caspase-3 (5.4 ± 1.5 vs. 0.5 ± 0.3 AU, p < 0.02), B-cell lymphoma protein 2-associated X (0.68 ± 0.07 vs. 0.04 ± 0.04 AU, p < 0.001), and reduced B-cell lymphoma protein 2 (0.29 ± 0.01 vs. 1.47 ± 0.54 AU, p < 0.05). We further observed elevated circulating natriuretic peptides and exercise intolerance in Ppara HepKO mice when compared to controls. Our data demonstrated that lipotoxicity, and fibrosis underlie cardiac dysfunction in MASLD.

Higher baseline serum bilirubin levels are associated with increased risk of early neurological deterioration in women with acute ischemic stroke

Background and objectives

Early neurological deterioration (END) occurs in up to one-third of patients with acute ischemic stroke (AIS) and associated with poor outcome. The role of serum bilirubin in END remains controversial. This study aims to investigate the association of total bilirubin (TBIL), direct bilirubin (DBIL) and indirect bilirubin (IBIL) with END.

Methods

This study was a cross-sectional retrospective study with 344 AIS patients enrolled. We retrospectively reviewed consecutive AIS patients with END through a medical record retrieval system and enrolled patients as control randomly from the AIS patients without END at the same period. The bilirubin levels were compared between the END group and No END group. The correlations of bilirubin with END were assessed according to the bilirubin tertiles on the cohort of different genders.

Results

In women, as the bilirubin level increased, the occurrence of END showed an increasing trend. The linear association was significant based on the tertiles of all bilirubin types (TBIL p = 0.003; DBIL p = 0.025; IBIL p = 0.025), while in men no similar trend was observed. After adjustment for confounders, higher TBIL (p for trend 0.009) and DBIL (p for trend 0.033) levels were associated with increased risk of END in women. The adjusted OR for T3 relative to T1 was 5.240 (95% CI 1.496-18.347) in TBIL and 3.549 (95% CI 1.089-11.566) in DBIL. Multivariate logistic regression showed that DBIL was independently associated with END in women (OR 1.717, 95% CI 1.106-2.666). The study also found that DBIL was superior to TBIL and IBIL in prediction of END occurrence in women, with greater predictive value.

Discussion

There were gender differences in the relationship between bilirubin and END, and DBIL level was positively associated with END occurrence in women, not in men. DBIL had greater incremental predictive value for END than TBIL and IBIL.

Glycocalyx-Mimicking Nanoparticles with Differential Organ Selectivity for Drug Delivery and Therapy

Organ-selective drug delivery is expected to maximize the efficacy of various therapeutic modalities while minimizing their systemic toxicity. Lipid nanoparticles and polymersomes can direct the organ-selective delivery of mRNAs or gene editing machineries, but their delivery is limited to mostly liver, spleen, and lung. A platform that enables delivery to these and other target organs is urgently needed. Here, a library of glycocalyx-mimicking nanoparticles (GlyNPs) comprising five randomly combined sugar moieties is generated, and direct in vivo library screening is used to identify GlyNPs with preferential biodistribution in liver, spleen, lung, kidneys, heart, and brain. Each organ-targeting GlyNP hit show cellular tropism within the organ. Liver, kidney, and spleen-targeting GlyNP hits equipped with therapeutics effectively can alleviate the symptoms of acetaminophen-induced liver injury, cisplatin-induced kidney injury, and immune thrombocytopenia in mice, respectively. Furthermore, the differential organ targeting of GlyNP hits is influenced not by the protein corona but by the sugar moieties displayed on their surface. It is envisioned that the GlyNP-based platform may enable the organ- and cell-targeted delivery of therapeutic cargoes.

Sex differences in the relationship between serum total bilirubin and risk of incident metabolic syndrome in community-dwelling adults: Propensity score analysis using longitudinal cohort data over 16 years

BACKGROUND

Research on identifiable risks for metabolic syndrome (MetS) is ongoing, and growing evidence suggests that bilirubin is a potent antioxidant and cytoprotective agent against MetS. However, there have been conflicting results on the association between bilirubin and MetS. Our study aimed to validate the association by separately stratifying data for men and women in a longitudinal prospective study.

METHODS

Data were derived from the Korean Genome Epidemiology Study provided by the Korea Centers for Disease Control and Prevention. Data from 5,185 adults aged 40-69 years (3,089 men and 2,096 women) without MetS were analyzed. The participants were divided according to sex-specific quartiles of serum total bilirubin levels and followed up biennially for 16 years (until 2018). The log-rank test was used for obtaining the Kaplan-Meier curves of cumulative incidence of MetS according to sex-specific serum total bilirubin quartiles, and the hazard ratios (HRs) with 95% confidence intervals (CIs) for incident metabolic syndrome were analyzed with a multiple Cox proportional hazard regression analysis model, after propensity score matching for removing differences at baseline.

RESULTS

With increasing serum total bilirubin quartiles, the incidence rate per 1000 person-years proportionally decreased in both men and women. After propensity score matching and adjusting for confounding variables, the HRs (95% CIs) for MetS of the highest quartile in reference to the lowest quartile were 1.00 (0.80-1.24) for men and 0.80 (0.65-0.99) for women. Higher quartiles of serum total bilirubin showed significantly lower cumulative incidence of MetS in women (log-rank test p = 0.009), but not in men (log-rank test p = 0.285).

CONCLUSION

Serum total bilirubin levels were significantly inversely associated with MetS in women, but there was no significant association observed in men. Sex differences in the effects of serum total bilirubin should be noted when predicting incident MetS by sex in clinical settings.

Bilirubin and postpartum depression: an observational and Mendelian randomization study

Background

Postpartum depression (PPD) is one of the most common complications of delivery and is usually disregarded. Several risk factors of PPD have been identified, but its pathogenesis has not been completely understood. Serum bilirubin has been found to be a predictor of depression, whose relationship with PPD has not been investigated.

Methods

Observational research was performed followed by a two-sample Mendelian randomization (MR) analysis. From 2017 to 2020, the clinical data of pregnant women were retrospectively extracted. Logistic regression and random forest algorithm were employed to assess the risk factors of PPD, including the serum levels of total bilirubin and direct bilirubin. To further explore their potential causality, univariable and multivariable Mendelian randomization (MVMR) were conducted. Sensitivity analyses for MR were performed to test the robustness of causal inference.

Results

A total of 1,810 patients were included in the PPD cohort, of which 631 (34.87%) were diagnosed with PPD. Compared with the control group, PPD patients had a significantly lower level of total bilirubin (9.2 μmol/L, IQR 7.7, 11.0 in PPD; 9.7 μmol/L, IQR 8.0, 12.0 in control, P < 0.001) and direct bilirubin (2.0 μmol/L, IQR 1.6, 2.6 in PPD; 2.2 μmol/L, IQR 1.7, 2.9 in control, P < 0.003). The prediction model identified eight independent predictive factors of PPD, in which elevated total bilirubin served as a protective factor (OR = 0.94, 95% CI 0.90-0.99, P = 0.024). In the MR analyses, genetically predicted total bilirubin was associated with decreased risk of PPD (IVW: OR = 0.86, 95% CI 0.76-0.97, P = 0.006), which remained consistent after adjusting educational attainment, income, and gestational diabetes mellitus. Conversely, there is a lack of solid evidence to support the causal relationship between PPD and bilirubin.

Conclusion

Our results suggested that decreased total bilirubin was associated with the incidence of PPD. Future studies are warranted to investigate its potential mechanisms and illuminate the pathogenesis of PPD.

FOXS1 is increased in liver fibrosis and regulates TGFβ responsiveness and proliferation pathways in human hepatic stellate cells

Liver fibrosis commences with liver injury stimulating transforming growth factor beta (TGFβ) activation of hepatic stellate cells (HSCs), causing scarring and irreversible damage. TGFβ induces expression of the transcription factor Forkhead box S1 (FOXS1) in hepatocytes and may have a role in the pathogenesis of hepatocellular carcinoma (HCC). To date, no studies have determined how it affects HSCs. We analyzed human livers with cirrhosis, HCC, and a murine fibrosis model and found that FOXS1 expression is significantly higher in fibrotic livers but not in HCC. Next, we treated human LX2 HSC cells with TGFβ to activate fibrotic pathways, and FOXS1 mRNA was significantly increased. To study TGFβ-FOXS1 signaling, we developed human LX2 FOXS1 CRISPR KO and scrambled control HSCs. To determine differentially expressed gene transcripts controlled by TGFβ-FOXS1, we performed RNA-seq in the FOXS1 KO and control cells and over 400 gene responses were attenuated in the FOXS1 KO HSCs with TGFβ-activation. To validate the RNA-seq findings, we used our state-of-the-art PamGene PamStation kinase activity technology that measures hundreds of signaling pathways nonselectively in real time. Using our RNA-seq data, kinase activity data, and descriptive measurements, we found that FOXS1 controls pathways mediating TGFβ responsiveness, protein translation, and proliferation. Our study is the first to identify that FOXS1 may serve as a biomarker for liver fibrosis and HSC activation, which may help with early detection of hepatic fibrosis or treatment options for end-stage liver disease.

Bilirubin Distribution in Plants at the Subcellular and Tissue Levels

In heterotrophs, heme degradation produces bilirubin, a tetrapyrrole compound that has antioxidant activity. In plants, heme is degraded in plastids and is believed to be converted to phytochromobilin rather than bilirubin. Recently, we used the bilirubin-inducible fluorescent protein UnaG to reveal that plants produce bilirubin via a non-enzymatic reaction with NADPH. In the present study, we used an UnaG-based live imaging system to visualize bilirubin accumulation in Arabidopsis thaliana and Nicotiana benthamiana at the organelle and tissue levels. In chloroplasts, bilirubin preferentially accumulated in the stroma, and the stromal bilirubin level increased upon dark treatment. Investigation of intracellular bilirubin distribution in leaves and roots showed that it accumulated mostly in plastids, with low levels detected in the cytosol and other organelles, such as peroxisomes, mitochondria and the endoplasmic reticulum. A treatment that increased bilirubin production in chloroplasts decreased the bilirubin level in peroxisomes, implying that a bilirubin precursor is transported between the two organelles. At the cell and tissue levels, bilirubin showed substantial accumulation in the root elongation region but little or none in the root cap and guard cells. Intermediate bilirubin accumulation was observed in other shoot and root tissues, with lower levels in shoot tissues. Our data revealed the distribution of bilirubin in plants, which has implications for the transport and physiological function of tetrapyrroles.

Factors associated with neonatal jaundice among neonates admitted at referral hospitals in northeast Ethiopia: a facility-based unmatched case-control study

BACKGROUND

Neonatal jaundice is a significant contributor to illness and death in newborns, leading to frequent admissions to neonatal intensive care units. To better understand this issue, a study was conducted to identify the factors contributing to neonatal jaundice among newborns admitted to Dessie and Woldia comprehensive specialized hospitals in northeast Ethiopia.

METHODS

The study took place from April 1 to May 30, 2022, using unmatched case-control design. A total of 320 neonates paired with their mothers were involved, including 64 cases and 256 controls. Data were collected through a structured interviewer-administered questionnaire and a review of medical records. The collected data were analyzed using SPSS Version 23, and a multivariate logistic regression model was employed to understand the relationship between independent factors and the occurrence of neonatal jaundice. Statistical significance was determined at a threshold of P value less than 0.05.

RESULTS

The study findings revealed that maternal age over 35 years, residing in urban areas [adjusted odds ratio (AOR) = 2.4, 95% confidence interval (CI): 1.23, 4.82], male gender (AOR = 4.3, 95% CI: 1.90, 9.74), prematurity (AOR = 3.9, 95% CI: 1.88, 8.09), and ABO incompatibility (AOR = 2.6, 95% CI: 1.16, 5.96) were significant determinants of neonatal jaundice. Conversely, the study indicated that cesarean birth was associated with a 76% lower likelihood of infant jaundice compared to vaginal delivery (AOR = 0.24, 95% CI: 0.08, 0.72).

CONCLUSION

To prevent, diagnose, and treat neonatal jaundice effectively, efforts should primarily focus on managing ABO incompatibility and early detection of prematurity. Additionally, special attention should be given to neonates born through vaginal delivery, those with mothers over 35 years old, and those residing in urban areas, as they are at higher risk of developing newborn jaundice. Close monitoring of high-risk mother-infant pairs during the antenatal and postnatal periods, along with early intervention, is crucial for reducing the severity of neonatal jaundice in this study setting.

A systemic lupus erythematosus patient with persistent elevated conjugated bilirubin as the initial symptom: A case report

RATIONALE

While some systemic lupus erythematosus (SLE) patients may experience varying degrees of liver function abnormalities, only a small portion of these cases have clinical significance, and the majority of patients typically exhibit low levels of serum bilirubin. However, in this article, we present a case of a middle-aged female patient with SLE who exhibited persistent skin jaundice as her initial symptom, offering a fresh perspective on diagnosing and treating patients who exhibit unexplained liver dysfunction and SLE combined with liver injury.

PATIENT CONCERNS

A 45-year-old woman was initially admitted to the hospital due to yellowing of the skin and sclera, and her symptoms did not improve significantly during treatment. The results were abnormal after relevant immunological tests.

DIAGNOSES

Persistent non-conjugated bilirubin elevation due to lupus hepatitis.

INTERVENTIONS

The use of methylprednisolone sodium succinate (40 mg/Qd) and mycophenolate mofetil (0.75 g/d) suppressed immunity, polyolefin choline (20 mL/d) and glutathione (0.6 g/Qd) improved liver function, and nutritional support therapy.

OUTCOMES

After 2 weeks of treatment, a significant decrease in the yellow skin and sclera of the patient was observed.

LESSONS

Most clinicians overlook that liver function abnormalities are the main manifestation of SLE, resulting in many patients not receiving timely treatment. This study highlights the importance that SLE is also a cause of abnormal liver function.

Adaptive metabolic response to short-term intensive fasting

BACKGROUND & AIMS

Short-term intensive fasting (STIF), known as beego in Chinese phonetic articulation, has been practiced for more than two thousand years. However, the potential risk of STIF and the body's response to the risk have not been adequately evaluated. This study aims to address this issue, focusing on the STIF-triggered metabolic response of the liver and kidney.

METHODS

The STIF procedure in the clinical trial includes a 7-day water-only intensive fasting phase and a 7-day gradual refeeding phase followed by a regular diet. The intensive fasting in humans was assisted with psychological induction. To gain insights not available in the clinical trial, we designed a STIF program for mice that resulted in similar phenotypes seen in humans. Plasma metabolic profiling and examination of gene expression as well as liver and kidney function were performed by omics, molecular, biochemical and flow cytometric analyses. A human cell line model was also used for mechanistic study.

RESULTS

Clinically significant metabolites of fat and protein were found to accumulate during the fasting phase, but they were relieved after gradual refeeding. Metabolomics profiling revealed a universal pattern in the consumption of metabolic intermediates, in which pyruvate and succinate are the two key metabolites during STIF. In the STIF mouse model, the accumulation of metabolites was mostly counteracted by the upregulation of catabolic enzymes in the liver, which was validated in a human cell model. Kidney filtration function was partially affected by STIF but could be recovered by refeeding. STIF also reduced oxidative and inflammatory levels in the liver and kidney. Moreover, STIF improved lipid metabolism in mice with fatty liver without causing accumulation of metabolites after STIF.

CONCLUSIONS

The accumulation of metabolites induced by STIF can be relieved by spontaneous upregulation of catabolic enzymes, suggesting an adaptive and protective metabolic response to STIF stress in the mammalian body.

Predictive value of bilirubin and serum γ-glutamyltranspeptidase levels in type-2 diabetes mellitus patients with acute coronary syndrome

BACKGROUND

Cardiovascular disease is a major complication of diabetes mellitus (DM). Type-2 DM (T2DM) is associated with an increased risk of cardiovascular events and mortality, while serum biomarkers may facilitate the prediction of these outcomes. Early differential diagnosis of T2DM complicated with acute coronary syndrome (ACS) plays an important role in controlling disease progression and improving safety.

AIM

To investigate the correlation of serum bilirubin and γ-glutamyltranspeptidase (γ-GGT) with major adverse cardiovascular events (MACEs) in T2DM patients with ACS.

METHODS

The clinical data of inpatients from January 2022 to December 2022 were analyzed retrospectively. According to different conditions, they were divided into the T2DM complicated with ACS group (T2DM + ACS, n = 96), simple T2DM group (T2DM, n = 85), and simple ACS group (ACS, n = 90). The clinical data and laboratory indices were compared among the three groups, and the correlations of serum total bilirubin (TBIL) levels and serum γ-GGT levels with other indices were discussed. T2DM + ACS patients received a 90-day follow-up after discharge and were divided into event (n = 15) and nonevent (n = 81) groups according to the occurrence of MACEs; Univariate and multivariate analyses were further used to screen the independent influencing factors of MACEs in patients.

RESULTS

The T2DM + ACS group showed higher γ-GGT, total cholesterol, low-density lipoprotein cholesterol (LDL-C) and glycosylated hemoglobin (HbA1c) and lower TBIL and high-density lipoprotein cholesterol levels than the T2DM and ACS groups (P < 0.05). Based on univariate analysis, the event and nonevent groups were significantly different in age (t = 3.3612, P = 0.0011), TBIL level (t = 3.0742, P = 0.0028), γ-GGT level (t = 2.6887, P = 0.0085), LDL-C level (t = 2.0816, P = 0.0401), HbA1c level (t = 2.7862, P = 0.0065) and left ventricular ejection fraction (LEVF) levels (t=3.2047, P = 0.0018). Multivariate logistic regression analysis further identified that TBIL level and LEVF level were protective factor for MACEs, and age and γ-GGT level were risk factors (P < 0.05).

CONCLUSION

Serum TBIL levels are decreased and γ-GGT levels are increased in T2DM + ACS patients, and the two indices are significantly negatively correlated. TBIL and γ-GGT are independent influencing factors for MACEs in such patients.

Role of Natural Compounds Modulating Heme Catabolic Pathway in Gut, Liver, Cardiovascular, and Brain Diseases

The crucial physiological process of heme breakdown yields biliverdin (BV) and bilirubin (BR) as byproducts. BV, BR, and the enzymes involved in their production (the "yellow players-YP") are increasingly documented as endogenous modulators of human health. Mildly elevated serum bilirubin concentration has been correlated with a reduced risk of multiple chronic pro-oxidant and pro-inflammatory diseases, especially in the elderly. BR and BV per se have been demonstrated to protect against neurodegenerative diseases, in which heme oxygenase (HMOX), the main enzyme in the production of pigments, is almost always altered. HMOX upregulation has been interpreted as a tentative defense against the ongoing pathologic mechanisms. With the demonstration that multiple cells possess YP, their propensity to be modulated, and their broad spectrum of activity on multiple signaling pathways, the YP have assumed the role of an adjustable system that can promote health in adults. Based on that, there is an ongoing effort to induce their activity as a therapeutic option, and natural compounds are an attractive alternative to the goal, possibly requiring only minimal changes in the life style. We review the most recent evidence of the potential of natural compounds in targeting the YP in the context of the most common pathologic condition of adult and elderly life.

Investigation of anti-neuronal antibodies and disparity in central hypersomnias

STUDY OBJECTIVES

Microbial antigens can elicit an immune response leading to the production of autoantibodies cross-reacting with autoantigens. Still, their clinical significance in human sera in the context of brain diseases is unclear. Therefore, assessment of natural autoantibodies reacting with their neuropeptides may elucidate the autoimmune etiology of central hypersomnias. The study aims to determine whether serum autoantibody levels differ in patients with different types of central hypersomnias (narcolepsy type 1 and 2, NT1 and NT2; idiopathic hypersomnia, IH) and healthy controls and if the differences could suggest the participation of autoantibodies in disease pathogenesis.

METHODS

Sera from 91 patients with NT1, 27 with NT2, 46 with IH, and 50 healthy controls were examined for autoantibodies against assorted neuropeptides. Participants were screened using questionnaires related to sleep disorders, quality of life, and mental health conditions. In addition, serum biochemical parameters and biomarkers of microbial penetration through the intestinal wall were determined.

RESULTS

A higher prevalence of autoantibodies against neuropeptides was observed only for alpha-melanocytes-stimulating hormone (α-MSH) and neuropeptide glutamic acid-isoleucine (NEI), which differed slightly among diagnoses. Patients with both types of narcolepsy exhibited signs of microbial translocation through the gut barrier. According to the questionnaires, patients diagnosed with NT2 or IH had subjectively worse life quality than patients with NT1. Patients displayed significantly lower levels of bilirubin and creatinine and slightly higher alkaline phosphatase values than healthy controls.

CONCLUSIONS

Overall, serum anti-neuronal antibodies prevalence is rare, suggesting that their participation in the pathophysiology of concerned sleep disorders is insignificant. Moreover, their levels vary slightly between diagnoses indicating no major diagnostic significance.

Glucocorticoids, their uses, sexual dimorphisms, and diseases: new concepts, mechanisms, and discoveries

The normal stress response in humans is governed by the hypothalamic-pituitary-adrenal (HPA) axis through heightened mechanisms during stress, raising blood levels of the glucocorticoid hormone cortisol. Glucocorticoids are quintessential compounds that balance the proper functioning of numerous systems in the mammalian body. They are also generated synthetically and are the preeminent therapy for inflammatory diseases. They act by binding to the nuclear receptor transcription factor glucocorticoid receptor (GR), which has two main isoforms (GRα and GRβ). Our classical understanding of glucocorticoid signaling is from the GRα isoform, which binds the hormone, whereas GRβ has no known ligands. With glucocorticoids being involved in many physiological and cellular processes, even small disruptions in their release via the HPA axis, or changes in GR isoform expression, can have dire ramifications on health. Long-term chronic glucocorticoid therapy can lead to a glucocorticoid-resistant state, and we deliberate how this impacts disease treatment. Chronic glucocorticoid treatment can lead to noticeable side effects such as weight gain, adiposity, diabetes, and others that we discuss in detail. There are sexually dimorphic responses to glucocorticoids, and women tend to have a more hyperresponsive HPA axis than men. This review summarizes our understanding of glucocorticoids and critically analyzes the GR isoforms and their beneficial and deleterious mechanisms and the sexual differences that cause a dichotomy in responses. We also discuss the future of glucocorticoid therapy and propose a new concept of dual GR isoform agonist and postulate why activating both isoforms may prevent glucocorticoid resistance.

Mildly elevated serum bilirubin and its correlations with lipid levels among male patients undergoing health checkups

BACKGROUND

Bilirubin's ability to lower lipid levels was confirmed by several studies, but those studies mainly focused on total bilirubin (TBil). The present study aimed to elucidate the correlations of the two subtypes of bilirubin with lipid levels.

METHODS

A total of 1732 male patients undergoing health checkups were categorized into three groups according to the levels of direct bilirubin (DBil) and indirect bilirubin (IBil). The differences in medical characteristics among the three groups were analysed.

RESULTS

Subjects in the elevated DBil group had the lowest serum alanine aminotransferase (ALT), total cholesterol (TC), blood urea nitrogen (BUN), γ-glutamyl transpeptidase (γ-GT), fasting blood glucose (FBG), haemoglobin (HGB), and triglyceride (TG) levels in contrast to the other groups (P < 0.01), while subjects in the elevated IBil group had the highest ALT, γ-GT, BUN, serum creatinine (SCR), HGB, TC, and TG levels among the three groups (P < 0.01). DBil levels exhibited a significant negative correlation with TC (r = -0.777, P < 0.01) and TG (r = -0.397, P < 0.01) levels, while IBil levels exhibited a significant positive correlation with TC (r = 0.790, P < 0.01) and TG (r = 0.302, P < 0.01) levels. The frequencies of abnormal TC, TG, HGB and BUN levels were the lowest in the elevated DBil group, while the levels of these four variables were the highest in the elevated IBil group. Mildly elevated DBil levels were related to lower TG (OR = 0.112, 95% CI = 0.027-0.458) and TC (OR = 0.097, 95% CI = 0.013-0.700), and mildly elevated IBil levels were connected with increased TC (OR = 3.436, 95% CI = 2.398-4.924) and TG (OR = 1.636, 95% CI = 1.163-2.303). DBil was an independent protective factor against increased TC (OR = 0.702, 95% CI = 0.602-0.817, P < 0.01) and TG (OR = 0.632, 95% CI = 0.541-0.739, P < 0.01) levels, and IBil was an independent risk factors for increased TC (OR = 1.251, 95% CI = 1.176-1.331, P < 0.01).

CONCLUSIONS

DBil was an independent protective factor against high TC and TG levels. IBil was an independent risk factors for elevated TC levels. The prognostic value of IBil levels warrants further attention.

Distinctive biochemistry profiles associated with hyperuricemia between Tibetans and Hans in China

Purpose

We sought to identify distinct risk factors for hyperuricemia in native Tibetan and immigrant Han populations in Tibet, China.

Methods

Three cohorts of male participants aged between 20 and 40 years were enrolled in this study. Biochemical parameters including serum uric acid (UA), fasting plasma glucose, insulin, lactate dehydrogenase (LDH), thyroxin, blood cell count, aminotransferase, and lipid profiles were analyzed. The association of risk factors with UA levels was evaluated using a multivariable line regression model. The effect of UA level on the biochemical parameters between the Hans and Tibetans was evaluated by two-way ANOVA.

Results

The prevalence of hyperuricemia (≥420 μmol/L) was 24.8% (62/250) in the Hans, similar to 23.8% (29/136) in the Tibetans. In the regression analysis, the risk factors that were significantly associated with UA in Hans did not apply to Tibetans. Tibetans had higher fasting insulin (P<0.05) and LDH (P<0.01) levels, in contrast with lower levels of triglycerides (P<0.05), total cholesterol (P<0.01), and low-density lipoprotein-cholesterol (P<0.01) than Hans in normal UA populations. Biochemistry analysis revealed lower albumin levels (P<0.001) and higher levels of all aminotransaminase and especially alkaline phosphatase (P<0.01) in Tibetans than in Hans in both populations. Compared with Hans, Tibetans had lower serum levels of urea, creatinine, and electrolytes in the normal UA population, which were further exacerbated in the high UA population. Tibetans had comparable white blood cell counts as Hans in both normal and high UA populations. In contrast, the red blood cell count and hemoglobin concentration were much lower in Tibetans than in Hans under high UA conditions.

Conclusions

The distinctive biochemistry between Tibetans and Hans may underlie the different etiologies of hyperuricemia in Tibet, China.

Correlation between pre-treatment serum total blood bilirubin and unconjugated bilirubin and prognosis in patients with colorectal cancer

BACKGROUND

Epidemiological studies have found that unconjugated bilirubin (UCB) levels are positively correlated with the incidence of colorectal cancer (CRC). Therefore, bilirubin may also play an important role in the prognosis of CRC.

AIM

To investigate the predictive value of total bilirubin (TBIL) and UCB in the prognosis of patients with CRC.

METHODS

A total of 142 CRC patients were selected as the research subjects in Jingxian Hospital, from October 2014 to May 2021. General and tumour-related clinical data at admission and the overall survival at 3 years after surgery were collected. The optimal cut-off values of TBIL and UCB were determined by receiver operating characteristic curve analysis. Univariate and multivariate Cox regression were used to analyse the effect of bilirubin level on the survival of CRC patients. The Kaplan-Meier method was used to assess the survival time.

RESULTS

The 3-year overall survival rate of CRC patients was significantly higher in the high TBIL (> 13.45 μmol/L) group than in the low TBIL (≤ 13.45 μmol/L) group (76.4% vs 37.1%; P < 0.05). The 3-year overall survival rate of CRC patients in the high UCB (> 10.75 μmol/L) group was significantly higher than that in the low UCB (≤ 10.75 μmol/L) group (83.3% vs 34.2%; P < 0.05). Multivariate Cox regression analysis showed that higher TBIL levels were an independent predictor of better prognosis in CRC patients (hazard ratio = 0.360, 95% confidence interval: 0.159-0.812, P = 0.014).

CONCLUSION

TBIL levels can be used as a prognostic indicator for CRC patients.

Predictive modeling of postoperative gastrointestinal dysfunction: the role of serum bilirubin, sodium levels, and surgical duration in gynecological cancer care

OBJECTIVE

To elucidate the role of preoperative serum bilirubin and sodium levels, along with the duration of surgery, in predicting postoperative gastrointestinal dysfunction (POGD) following gynecological cancer surgery, informing tailored perioperative strategies.

METHODS

We conducted a retrospective analysis of 281 patients undergoing gynecological cancer surgery between 2018 and 2023. This analysis focused on preoperative serum bilirubin and sodium levels and intraoperative factors (surgical duration) as potential predictors of POGD. Logistic regression models were utilized for analysis, controlling for relevant confounders.

RESULTS

Elevated preoperative serum bilirubin was associated with a reduced risk of POGD (mean level in non-POGD cases: 14.172 ± 4.0701, vs. POGD cases: 9.6429 ± 3.5351; p <  0.001), suggesting a protective role. Lower preoperative sodium levels were identified in the POGD group (136.26 mEq/L [IQR: 135.2-137.63]) compared to the non-POGD group (139.32 mEq/L [IQR: 137.7-140.75]; p <  0.001), highlighting its predictive value. Additionally, longer surgical duration was associated with increased POGD incidence, with POGD cases experiencing surgeries lasting 6.1547 ± 1.9426 hours compared to 4.5959 ± 1.5475 hours in non-POGD cases (p <  0.001).

CONCLUSION

Our findings underscore the importance of serum bilirubin, sodium levels, and surgical duration as significant predictors of POGD in patients undergoing gynecological cancer surgery. These indicators should be integrated into a predictive model, aiding clinicians in identifying high-risk patients, allowing for personalized perioperative care adjustments, potentially mitigating POGD risks.

Association of urinary bisphenols with oxidative stress and inflammatory markers and their role in obesity

Bisphenol A (BPA) and its substitutes are widely used in daily life. Animal and cell line experiments have confirmed the effects of bisphenols on oxidative stress and inflammation. However, current population evidence for the effects of BPA alternatives, such as bisphenol F (BPF) and bisphenol S (BPS), on oxidative stress and inflammation is still sparse. Based on the National Health and Nutrition Examination Survey 2013-2016 data, our study used linear regression, weighted quantile sum model, and Bayesian kernel machine regression model to evaluate the effects of BPA, BPS, and BPF alone and in combination on oxidative stress (serum total bilirubin, and iron) and inflammation (alkaline phosphatase, C-reactive protein, γ-glutamyl transferase ferritin, neutrophil count, lymphocyte count, and neutrophil-to-lymphocyte ratio) markers. On this basis, the possible roles of oxidative stress and inflammation in obesity, which is associated with exposure to bisphenols (BPs), were initially explored. Based on the different covariates selected, a total of 3039 and 2258 participants were included in our study for models 1 and 2, respectively; the median age of participants was 48 years, and 48.7 % were male. Based on all models, our results showed that exposure to BPs alone or in combination was associated with downregulation of serum total bilirubin. Urinary BPF concentration was specifically associated with the neutrophil-to-lymphocyte ratio. Serum total bilirubin may play a role in the association between obesity and BP mixture exposure. Upregulation of the neutrophil-to-lymphocyte ratio was not associated with obesity. In conclusion, our study found that single or combined exposure to BPs, as measured in urine, may be associated with changes in oxidative stress and inflammatory markers, and a decrease in serum total bilirubin may play a mediating role in BP-induced obesity.

Study on the Common Molecular Mechanism of Metabolic Acidosis and Myocardial Damage Complicated by Neonatal Pneumonia

Pneumonia is a common clinical disease in the neonatal period and poses a serious risk to infant health. Therefore, the understanding of molecular mechanisms is of great importance for the development of methods for the rapid and accurate identification, classification and staging, and even disease diagnosis and therapy of pneumonia. In this study, a nontargeted metabonomic method was developed and applied for the analysis of serum samples collected from 20 cases in the pneumonia control group (PN) and 20 and 10 cases of pneumonia patients with metabolic acidosis (MA) and myocardial damage (MD), respectively, with the help of ultrahigh-performance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS). The results showed that compared with the pneumonia group, 23 and 21 differential metabolites were identified in pneumonia with two complications. They showed high sensitivity and specificity, with the area under the curve (ROC) of the receiver operating characteristic curve (ROC) larger than 0.7 for each differential molecule. There were 14 metabolites and three metabolic pathways of sphingolipid metabolism, porphyrin and chlorophyll metabolism, and glycerophospholipid metabolism existing in both groups of PN and MA, and PN and MD, all involving significant changes in pathways closely related to amino acid metabolism disorders, abnormal cell apoptosis, and inflammatory responses. These findings of molecular mechanisms should help a lot to fully understand and even treat the complications of pneumonia in infants.

Interplay Of Serum Bilirubin and Tobacco Smoking with Lung and Head and Neck Cancers in a Diverse, EHR-linked Los Angeles Biobank

Background

Bilirubin is a potent antioxidant with a protective role in many diseases. We examined the relationships between serum bilirubin (SB) levels, tobacco smoking (a known cause of low SB), and aerodigestive cancers, grouped as lung cancers (LC) and head and neck cancers (HNC).

Methods

We examined the associations between SB, LC, and HNC using data from 393,210 participants from a real-world, diverse, de-identified data repository and biobank linked to the UCLA Health system. We employed regression models, propensity score matching, and polygenic scores to investigate the associations and interactions between SB, tobacco smoking, LC, and HNC.

Results

Current tobacco smokers showed lower SB (-0.04mg/dL, 95% CI: [-0.04, -0.03]), compared to never-smokers. Lower SB levels were observed in HNC and LC cases (-0.10 mg/dL, [-0.13, -0.09] and - 0.09 mg/dL, CI [-0.1, -0.07] respectively) compared to cancer-free controls with the effect persisting after adjusting for smoking. SB levels were inversely associated with HNC and LC risk (ORs per SD change in SB: 0.64, CI [0.59,0.69] and 0.57, CI [0.43,0.75], respectively). Lastly, a polygenic score (PGS) for SB was associated with LC (OR per SD change of SB-PGS: 0.71, CI [0.67, 0.76]).

Conclusions

Low SB levels are associated with an increased risk of both HNC and LC, independent of the effect of tobacco smoking. Additionally, tobacco smoking demonstrated a strong interaction with SB on LC risk. Lastly, genetically predicted low SB (using a polygenic score) is negatively associated with LC. These findings suggest that SB could serve as a potential early and low-cost biomarker for LC and HNC. The interaction with tobacco smoking suggests that smokers with lower bilirubin could likely be at higher risk for LC compared to never smokers, suggesting the utility of SB in risk stratification for patients at risk for LC. Lastly, the results of the polygenic score analyses suggest potential shared biological pathways between the genetic control of SB and the risk of LC development.

Loss of Biliverdin Reductase Increases Oxidative Stress in the Cyanobacterium Synechococcus sp. PCC 7002

Oxygenic photosynthesis requires metal-rich cofactors and electron-transfer components that can produce reactive oxygen species (ROS) that are highly toxic to cyanobacterial cells. Biliverdin reductase (BvdR) reduces biliverdin IXα to bilirubin, which is a potent scavenger of radicals and ROS. The enzyme is widespread in mammals but is also found in many cyanobacteria. We show that a previously described bvdR mutant of Synechocystis sp. PCC 6803 contained a secondary deletion mutation in the cpcB gene. The bvdR gene from Synechococcus sp. PCC 7002 was expressed in Escherichia coli, and recombinant BvdR was purified and shown to reduce biliverdin to bilirubin. The bvdR gene was successfully inactivated in Synechococcus sp. PCC 7002, a strain that is naturally much more tolerant of high light and ROS than Synechocystis sp. PCC 6803. The bvdR mutant strain, BR2, had lower total phycobiliprotein and chlorophyll levels than wild-type cells. As determined using whole-cell fluorescence at 77 K, the photosystem I levels were also lower than those in wild-type cells. The BR2 mutant had significantly higher ROS levels compared to wild-type cells after exposure to high light for 30 min. Together, these results suggest that bilirubin plays an important role as a scavenger for ROS in Synechococcus sp. PCC 7002. The oxidation of bilirubin by ROS could convert bilirubin to biliverdin IXα, and thus BvdR might be important for regenerating bilirubin. These results further suggest that BvdR is a key component of a scavenging cycle by which cyanobacteria protect themselves from the toxic ROS byproducts generated during oxygenic photosynthesis.

Interplay Of Serum Bilirubin and Tobacco Smoking with Lung and Head and Neck Cancers in a Diverse, EHR-linked Los Angeles Biobank

Background

Bilirubin is a potent antioxidant with a protective role in many diseases. We examined the relationships between serum bilirubin (SB) levels, tobacco smoking (a known cause of low SB), and aerodigestive cancers, grouped as lung (LC) and head and neck (HNC).

Methods

We examined the associations between SB, LC and HNC using data from 393,210 participants from UCLA Health, employing regression models, propensity score matching, and polygenic scores.

Results

Current tobacco smokers showed lower SB (-0.04mg/dL, 95% CI: [-0.04, -0.03]), compared to never-smokers. Lower SB levels were observed in HNC and LC cases (-0.10 mg/dL, [-0.13, -0.09] and -0.09 mg/dL, CI [-0.1, -0.07] respectively) compared to cancer-free controls with the effect persisting after adjusting for smoking. SB levels were inversely associated with HNC and LC risk (ORs per SD change in SB: 0.64, CI [0.59,0.69] and 0.57, CI [0.43,0.75], respectively). Lastly, a polygenic score (PGS) for SB was associated with LC (OR per SD change of SB-PGS: 0.71, CI [0.67, 0.76]).

Conclusions

Low SB levels are associated with an increased risk of both HNC and LC, independent of the effect of tobacco smoking with tobacco smoking demonstrating a strong interaction with SB on LC risk. Additionally, genetically predicted low SB (from polygenic scores) is negatively associated with LC.

Impact

These findings suggest that SB could serve as a potential early biomarker for LC and HNC.

Clinical and genetic definition of serum bilirubin levels for the diagnosis of Gilbert syndrome and hypobilirubinemia

BACKGROUND AND AIMS

Gilbert syndrome (GS) is genotypically predetermined by UGT1A1*28 homozygosity in Europeans and is phenotypically defined by hyperbilirubinemia using total bilirubin (TB) cutoff ≥1mg/dL (17 μmol/L). The prevalence of illnesses associated with GS and hypobilirubinemia has never been studied prospectively. As TB varies with UGT1A1*28 genotyping, sex, and age, we propose stratified definitions of TB reference intervals and report the prevalence of illnesses and adjusted 15 years survival.

METHODS

UK Biobank with apparently healthy liver participants (middle-aged, n=138,125) were analyzed after the exclusion of of nonhealthy individuals. The stratified TB was classified as GS when TB >90th centile; <10th centile indicated hypobilirubinemia, and between the 10th and 90th centile was normobilirubinemia. We compared the prevalence and survival rates of 54 illnesses using odds ratio (OR), logistic regression, and Cox models adjusted for confounders, and causality by Mendelian randomizations.

RESULTS

In women, we identified 10% (7,741/76,809) of GS versus 3.7% (2,819/76,809) using the historical cutoff of ≥1 mg/dL (P<0.0001). When GS and hypobilirubinemia participants were compared with normobilirubinemia, after adjustment and Mendelian randomizations, only cholelithiasis prevalence was significantly higher (OR=1.50; 95% CI [1.3-1.7], P=0.001) in men with GS compared with normobilirubinemia and in causal association with bilirubin (P=0.04). No adjusted survival was significantly associated with GS or hypobilirubinemia.

CONCLUSIONS

In middle-aged Europeans, the stratified TB demonstrates a careless GS underestimation in women when using the standard unisex 1 mg/dL cutoff. The prevalence of illnesses is different in GS and hypobilirubinemia as well as survivals before adjusting for confounding factors. With the exception of cholelithiasis in men, these differences were no more significant after adjustment and Mendelian randomization.

Antioxidative Stress Metabolic Pathways in Moderately Active Individuals

Physical activity (PA) is known to have beneficial effects on health, primarily through its antioxidative stress properties. However, the specific metabolic pathways that underlie these effects are not fully understood. This study aimed to investigate the metabolic pathways that are involved in the protective effects of moderate PA in non-obese and healthy individuals. Data on 305 young, non-obese participants were obtained from the Qatar Biobank. The participants were classified as active or sedentary based on their self-reported PA levels. Plasma metabolomics data were collected and analyzed to identify differences in metabolic pathways between the two groups. The results showed that active participants had increased activation of antioxidative, stress-related pathways, including lysoplasmalogen, plasmalogen, phosphatidylcholine, vitamin A, and glutathione. Additionally, there were significant associations between glutathione metabolites and certain clinical traits, including bilirubin, uric acid, hemoglobin, and iron. This study provides new insights into the metabolic pathways that are involved in the protective effects of moderate PA in non-obese and healthy individuals. The findings may have implications for the development of new therapeutic strategies that target these pathways.

Hepatic insulin receptor: new views on the mechanisms of liver disease

Over 65 % of people with obesity display the metabolic-associated fatty liver disease (MAFLD), which can manifest as steatohepatitis, fibrosis, cirrhosis, or liver cancer. The development and progression of MAFLD involve hepatic insulin resistance and reduced insulin clearance. This review discusses the relationships between altered insulin signaling, hepatic insulin resistance, and reduced insulin clearance in the development of MAFLD and how this provides the impetus for exploring the use of insulin sensitizers to curb this disease. The review also explores the role of the insulin receptor in hepatocytes and hepatic stellate cells and how it signals in metabolic and end-stage liver diseases. Finally, we discuss new research findings that indicate that advanced hepatic diseases may be an insulin-sensitive state in the liver and deliberate whether insulin sensitizers should be used to manage late-stage liver diseases.

Mechanisms Linking Metabolic-Associated Fatty Liver Disease (MAFLD) to Cardiovascular Disease

PURPOSE OF REVIEW

Metabolic-associated fatty liver disease (MAFLD) is a condition of fat accumulation in the liver that occurs in the majority of patients in combination with metabolic dysfunction in the form of overweight or obesity. In this review, we highlight the cardiovascular complications in MAFLD patients as well as some potential mechanisms linking MAFLD to the development of cardiovascular disease and highlight potential therapeutic approaches to treating cardiovascular diseases in patients with MAFLD.

RECENT FINDINGS

MAFLD is associated with an increased risk of cardiovascular diseases (CVD), including hypertension, atherosclerosis, cardiomyopathies, and chronic kidney disease. While clinical data have demonstrated the link between MAFLD and the increased risk of CVD development, the mechanisms responsible for this increased risk remain unknown. MAFLD can contribute to CVD through several mechanisms including its association with obesity and diabetes, increased levels of inflammation, and oxidative stress, as well as alterations in hepatic metabolites and hepatokines. Therapies to potentially treat MAFLD-induced include statins and lipid-lowering drugs, glucose-lowering agents, antihypertensive drugs, and antioxidant therapy.

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.

Inflammation, Dopaminergic Brain and Bilirubin

Dopamine is a well-known neurotransmitter due to its involvement in Parkinson's disease (PD). Dopamine is not only involved in PD but also controls multiple mental and physical activities, such as the pleasure of food, friends and loved ones, music, art, mood, cognition, motivation, fear, affective disorders, addiction, attention deficit disorder, depression, and schizophrenia. Dopaminergic neurons (DOPAn) are susceptible to stressors, and inflammation is a recognized risk for neuronal malfunctioning and cell death in major neurodegenerative diseases. Less is known for non-neurodegenerative conditions. Among the endogenous defenses, bilirubin, a heme metabolite, has been shown to possess important anti-inflammatory activity and, most importantly, to prevent DOPAn demise in an ex vivo model of PD by acting on the tumor necrosis factor-alpha (TNFα). This review summarizes the evidence linking DOPAn, inflammation (when possible, specifically TNFα), and bilirubin as an anti-inflammatory in order to understand what is known, the gaps that need filling, and the hypotheses of anti-inflammatory strategies to preserve dopamine homeostasis with bilirubin included.

Active Estrogen-Succinate Metabolism Promotes Heme Accumulation and Increases the Proliferative and Invasive Potential of Endometrial Cancer Cells

Uterine endometrial cancer (UEC) is an estrogen-related tumor. Succinate and heme metabolism play important roles in the progression of multiple tumors. However, the relationship between estrogen, succinate, and heme metabolism and related regulatory mechanisms remain largely unknown. In this study, we observed that the expression of aminolevulinate delta synthase 1 (ALAS1) and solute carrier family member 38 (SLC25A38) in UEC tissues is significantly higher than that in normal tissues. Further analysis showed that estrogen and succinate increased the expression of ALAS1 and SLC25A38 in uterine endometrial cancer cells (UECC), and the administration of succinate upregulated the level of the estrogen receptor (ER). Silencing nuclear receptor coactivator 1 (NCOA1) reversed the effects of estrogen and succinate via downregulation of ALAS1 expression. Additionally, exposure of UECC to heme increased cell viability and invasiveness, while silencing the NCOA1 gene weakened this effect. These findings revealed that estrogen and succinate can synergistically increase the expression of ALAS1 and SLC25A38 via the ERβ/NCOA1 axis, promoting heme accumulation and increasing the proliferative and invasive potential of UECC.

Loss of hepatic PPARα in mice causes hypertension and cardiovascular disease

The leading cause of death in patients with nonalcoholic fatty liver disease (NAFLD) is cardiovascular disease (CVD). However, the mechanisms are unknown. Mice deficient in hepatocyte proliferator-activated receptor-α (PPARα) (PparaHepKO) exhibit hepatic steatosis on a regular chow diet, making them prone to manifesting NAFLD. We hypothesized that the PparaHepKO mice might be predisposed to poorer cardiovascular phenotypes due to increased liver fat content. Therefore, we used PparaHepKO and littermate control mice fed a regular chow diet to avoid complications with a high-fat diet, such as insulin resistance and increased adiposity. After 30 wk on a standard diet, male PparaHepKO mice exhibited elevated hepatic fat content compared with littermates as measured by Echo MRI (11.95 ± 1.4 vs. 3.74 ± 1.4%, P < 0.05), hepatic triglycerides (1.4 ± 0.10 vs. 0.3 ± 0.01 mM, P < 0.05), and Oil Red O staining, despite body weight, fasting blood glucose, and insulin levels being the same as controls. The PparaHepKO mice also displayed elevated mean arterial blood pressure (121 ± 4 vs. 108 ± 2 mmHg, P < 0.05), impaired diastolic function, cardiac remodeling, and enhanced vascular stiffness. To determine mechanisms controlling the increase in stiffness in the aorta, we used state-of-the-art PamGene technology to measure kinase activity in this tissue. Our data suggest that the loss of hepatic PPARα induces alterations in the aortas that reduce the kinase activity of tropomyosin receptor kinases and p70S6K kinase, which might contribute to the pathogenesis of NAFLD-induced CVD. These data indicate that hepatic PPARα protects the cardiovascular system through some as-of-yet undefined mechanism.

Bilirubin is produced nonenzymatically in plants to maintain chloroplast redox status

Bilirubin, a potent antioxidant, is a product of heme catabolism in heterotrophs. Heterotrophs mitigate oxidative stress resulting from free heme by catabolism into bilirubin via biliverdin. Although plants also convert heme to biliverdin, they are generally thought to be incapable of producing bilirubin because they lack biliverdin reductase, the enzyme responsible for bilirubin biosynthesis in heterotrophs. Here, we demonstrate that bilirubin is produced in plant chloroplasts. Live-cell imaging using the bilirubin-dependent fluorescent protein UnaG revealed that bilirubin accumulated in chloroplasts. In vitro, bilirubin was produced nonenzymatically through a reaction between biliverdin and reduced form of nicotinamide adenine dinucleotide phosphate at concentrations comparable to those in chloroplasts. In addition, increased bilirubin production led to lower reactive oxygen species levels in chloroplasts. Our data refute the generally accepted pathway of heme degradation in plants and suggest that bilirubin contributes to the maintenance of redox status in chloroplasts.

Association of Inflammatory and Oxidative Status Markers with Metabolic Syndrome and Its Components in 40-to-45-Year-Old Females: A Cross-Sectional Study

Oxidative stress and sterile inflammation play roles in the induction and maintenance of metabolic syndrome (MetS). This study cohort included 170 females aged 40 to 45 years who were categorized according to the presentation of MetS components (e.g., central obesity, insulin resistance, atherogenic dyslipidemia, and elevated systolic blood pressure) as controls not presenting a single component (n = 43), those with pre-MetS displaying one to two components (n = 70), and females manifesting MetS, e.g., ≥3 components (n = 53). We analyzed the trends of seventeen oxidative and nine inflammatory status markers across three clinical categories. A multivariate regression of selected oxidative status and inflammatory markers on the components of MetS was performed. Markers of oxidative damage (malondialdehyde and advanced-glycation-end-products-associated fluorescence of plasma) were similar across the groups. Healthy controls displayed lower uricemia and higher bilirubinemia than females with MetS; and lower leukocyte counts, concentrations of C-reactive protein, interleukine-6, and higher levels of carotenoids/lipids and soluble receptors for advanced glycation end-products than those with pre-MetS and MetS. In multivariate regression models, levels of C-reactive protein, uric acid, and interleukine-6 were consistently associated with MetS components, although the impacts of single markers differed. Our data suggest that a proinflammatory imbalance precedes the manifestation of MetS, while an imbalance of oxidative status accompanies overt MetS. Further studies are needed to elucidate whether determining markers beyond traditional ones could help improve the prognosis of subjects at an early stage of MetS.

Total Bilirubin Yields Prognostic Information Following a Myocardial Infarction in the Elderly

Total bilirubin consists of an unconjugated form, solubilized by its binding to albumin, and a conjugated form representing a minor part of the circulating bilirubin. As total bilirubin in physiological concentrations is a powerful antioxidant, its concentration gradient may reflect the health status of an individual, and serve as a prognostic indicator of outcome in primary and secondary cardiovascular disease prevention. The aim of this study was to assess the association between total bilirubin and incident cardiovascular events following a myocardial infarction. Total bilirubin in serum was measured at baseline 2-8 weeks after hospitalization for an MI in 881 patients, aged 70 to 82 years, included in the OMEMI (Omega-3 Fatty acids in Elderly with Myocardial Infarction) study, where patients were followed-up for up to 2 years. The first major adverse clinical event (MACE) was the primary endpoint and consisted of nonfatal MI, unscheduled coronary revascularization, stroke, hospitalization for heart failure or all-cause death. As total bilirubin was non-normally distributed, log-transformed values and quartiles of bilirubin were analyzed using Cox regression models. The median (Q1, and Q3) baseline concentration of bilirubin was 11 (9, and 14) µmol/L, and higher log-transformed concentrations were associated with male sex, lower New York Heart Association (NYHA) class and non-smoking. MACE occurred in 177 (20.1%) patients during the follow-up. Higher concentrations of bilirubin were associated with a lower risk of MACE: HR 0.67 (95%CI 0.47-0.97) per log-unit increase, p = 0.032. Patients in the lowest quartile of bilirubin (<9 µmol/L) had the highest risk with HR 1.61 (95%CI 1.19-2.18), p = 0.002, compared to quartiles 2-4. This association remained significant even after adjusting for age, sex, body mass index (BMI), smoking status, NYHA class and treatment allocation: HR 1.52 (1.21-2.09), p = 0.009. Low concentrations of bilirubin (<9 µmol/L) are associated with increased nonfatal cardiovascular events or death in elderly patients with a recent myocardial infarction.

Fatty Acids and Bilirubin as Intrinsic Autofluorescence Serum Biomarkers of Drug Action in a Rat Model of Liver Ischemia and Reperfusion

The autofluorescence of specific fatty acids, retinoids, and bilirubin in crude serum can reflect changes in liver functional engagement in maintaining systemic metabolic homeostasis. The role of these fluorophores as intrinsic biomarkers of pharmacological actions has been investigated here in rats administered with obeticholic acid (OCA), a Farnesoid-X Receptor (FXR) agonist, proven to counteract the increase of serum bilirubin in hepatic ischemia/reperfusion (I/R) injury. Fluorescence spectroscopy has been applied to an assay serum collected from rats submitted to liver I/R (60/60 min ± OCA administration). The I/R group showed changes in the amplitude and profiles of emission spectra excited at 310 or 366 nm, indicating remarkable alterations in the retinoid and fluorescing fatty acid balance, with a particular increase in arachidonic acid. The I/R group also showed an increase in bilirubin AF, detected in the excitation spectra recorded at 570 nm. OCA greatly reversed the effects observed in the I/R group, confirmed by the biochemical analysis of bilirubin and fatty acids. These results are consistent with a relationship between OCA anti-inflammatory effects and the acknowledged roles of fatty acids as precursors of signaling agents mediating damaging responses to harmful stimuli, supporting serum autofluorescence analysis as a possible direct, real-time, cost-effective tool for pharmacological investigations.

The physiology of bilirubin: health and disease equilibrium

Bilirubin has several physiological functions, both beneficial and harmful. In addition to reactive oxygen species-scavenging activities, bilirubin has potent immunosuppressive effects associated with long-term pathophysiological sequelae. It has been recently recognized as a hormone with endocrine actions and interconnected effects on various cellular signaling pathways. Current studies show that bilirubin also decreases adiposity and prevents metabolic and cardiovascular diseases. All in all, the physiological importance of bilirubin is only now coming to light, and strategies for increasing plasma bilirubin levels to combat chronic diseases are starting to be considered. This review discusses the beneficial effects of increasing plasma bilirubin, incorporates emerging areas of bilirubin biology, and provides key concepts to advance the field.

Circulating Total Bilirubin and Long-Term Prognosis in Patients With Previous Myocardial Infarction

Background

Although experimental studies have demonstrated the protective role of total bilirubin (TBil) in cardiovascular diseases, several previous clinical observations are controversial. More importantly, no data are currently available regarding the relation of TBil to major adverse cardiovascular events (MACE) in patients with previous myocardial infarction (MI).

Objectives

This study sought to explore the association between TBil and long-term clinical outcomes in patients with previous MI.

Methods

A total of 3,809 patients who are post-MI were consecutively enrolled in this prospective study. Cox regression models using HRs and CIs were applied to investigate associations between the TBil concentration category (group 1: bottom to median tertiles within the reference range; group 2: top tertile; group 3: above reference range) and main outcome (recurrent MACE) as well as secondary outcomes (hard endpoints and all-cause mortality).

Results

During the 4-year follow-up period, 440 patients (11.6%) suffered from recurrent MACE. Kaplan-Meier survival analysis showed the lowest MACE incidence in group 2 (P < 0.001). When compared with the reference group (group 1) in multivariable analysis, a J-shaped association was apparent for MACE, with decreased risk in group 2 (HR: 0.76; 95% CI: 0.59-0.96) and elevated risk in group 3 (HR: 1.29; 95% CI: 1.03-1.61). Similar associations were identified regarding hard endpoints and all-cause mortality. Moreover, TBil demonstrated incremental discriminatory strength when added to the predictive model.

Conclusions

In this prospective cohort study with long-term follow-up, higher TBil levels within the physiological range reduced the incidence of long-term cardiovascular events in patients who are post-MI.

Heme, Heme Oxygenase-1, Statins, and SARS-CoV-2

Heme, a metalloporphyrin, or more specifically, a tetrapyrrole containing ferrous iron, is an ancient molecule [...]

Serum bilirubin levels are negatively associated with atherogenic lipids in Saudi subjects with type 2 diabetes: A pilot study

<b>Background: </b>Recent research has demonstrated the possible relevance of bilirubin in metabolic and cardiovascular disorders. Lipid abnormalities are a major problem that is related with an increased risk of cardiovascular disease in diabetics. This study examined the relationship between serum bilirubin and direct bilirubin concentrations and atherogenic lipids in patients with type 2 diabetes (T2DM).<br /> <b>Methods</b>: This cross-sectional included 67 patients with type 2 diabetes and 39 matched healthy control. The lipid profile, including total cholesterol, HDL-C, and TG levels, fasting blood glucose, total bilirubin, direct bilirubin, ALT, AST, and ALP were measured using a dimension EXL clinical chemistry analyzer (Siemens Healthcare Diagnostics). Cholesterol in VLDL, LDL, and sdLDL were calculated from standard lipid assay results by the equations of Sampson et al.<br /> <b>Results</b>: Serum bilirubin was lower in non T2DM subjects nearly significant (p=0.0.51) whereas direct bilirubin concentrations were lower in T2DM (p=0.008). ALT, AST, and ALP levels were higher in T2DM groups. The mean values of LDL-C, sdLDL-C, non HDL-C and VLDL-C were significantly increased in T2DM group and lower HDL-C. An inverse relationship could be observed with increase in serum total bilirubin and serum levels of LDL-C (r²=0.139, p&lt;0.005), sdLDL-C (r²=0.137, p&lt;0.005), VLDL-C (r²=0.074, p&lt;0.044), and non HDL-C (r²=0.166, p&lt;0.002) in T2DM group. The same inverse relationship was observed with serum direct bilirubin and serum levels of LDL-C (r²=0.133, p&lt;0.006), sdLDL-C (r²=0.172, p&lt;0.001), VLDL-C (r²=0.118, p&lt;0.01), and non HDL-C (r²=0.182, p&lt;0.001) in T2DM group.<br /> <b>Conclusions</b>: A significant negative association was found between serum bilirubin levels and direct serum bilirubin with atherogenic lipids, suggesting that serum bilirubin may protect T2DM patients from development of cardiovascular disease. These findings indicate the need for additional research in a large cohort.

Heme oxygenase-1 prevents non-alcoholic steatohepatitis through modulating mitochondrial quality control

AIM

Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease (NAFLD) and lacks effective treatment options. Heme oxygenase-1 (HO-1) is a critical defense against oxidative stress and inflammation in the liver injury. This study aims to investigate the protective role and underlying mechanisms of HO-1 in NASH pathogenesis.

METHODS

The hepatocyte-specific HO-1 knockout (HO-1^HEPKO ) mice on a C57BL/6J background (HO-1^fl/fl /Alb-Cre) were generated and fed a high-fat/western-style diet (HFD) or methionine-choline-deficient diet (MCD). Changes in mitochondrial ultrastructure were observed by transmission electron microscopy and confocal microscopy. A mitochondrial PCR array was used to identify the crucial genes associated with mitochondrial dysfunction.

RESULTS

Hepatocyte-specific HO-1^HEPKO mice developed steatohepatitis with severe steatosis, ballooning, and necroinflammation. Dysregulated hepatic expression of mitochondria-related proteins, including DRP1, Tomm20, MFN1 and MFN2 were detected in NASH animals. Ultrastructural mitochondrial damage was observed in HO-1^HEPKO mice. Mitochondrial dysfunction was recapitulated in HO-1-knockdown cells in vitro, as evidenced by decreased membrane potential, reduced ATP content, and mtDNA damage. Conversely, HO-1 overexpression restored these changes in vitro. Mechanistically, HO-1 deficiency reduced the inhibitory effect on Tomm20, leading to mitochondrial dysfunction, and thereby causing steatohepatitis.

CONCLUSIONS

HO-1 attenuates diet-induced steatohepatitis by preventing mitochondrial dysfunction, indicating that HO-1 may constitute a potential therapeutic target for NASH.

Evaluating individual biomarkers for predicting health risks in zoo-housed chimpanzees (Pan troglodytes) and bonobos (Pan paniscus)

Although biomarkers are often used for predicting morbidity and mortality in humans, similar data are lacking in our closest relatives. This study analyzed 16 biomarkers in zoo-housed chimpanzees and bonobos from serum samples collected during both routine and nonroutine veterinary immobilizations. Generalized linear and generalized linear mixed models were used to determine the efficacy of each biomarker to predict all-cause morbidity, defined as the presence of at least one chronic condition, or cardiac disease as a subset of all-cause morbidity. Cox proportional hazards models were used to examine associations between biomarkers and mortality risk from any cause. Analyses were conducted using two data sets for each species, one with all values retained (chimpanzees: n = 148; bonobos: n = 33) and the other from samples collected during routine immobilizations only (chimpanzees: n = 95; bonobos: n = 23). Consistent results across both data sets in chimpanzees included associations of higher cortisol with all-cause morbidity risk, lower creatinine with cardiac disease risk, and higher creatinine with mortality risk, and in bonobos were increased cardiac disease risk with higher cortisol and lower dehydroepiandrosterone-sulfate, fructosamine, and triglycerides. However, there were some inconsistencies between data sets, such as tumor necrosis factor-α predicting mortality risk positively in chimpanzees when all values were retained, but negatively for routine values only. Despite the close evolutionary relationships between chimpanzees and bonobos, the only result observed in both species was a negative association between albumin and mortality risk in the all values retained data sets. Thus, data suggest some biomarkers may be useful predictors of future health outcomes, although a better understanding of both individual and species variation in biomarkers and their contribution to health risks is needed.

Bilirubin Nanoparticle Treatment in Obese Mice Inhibits Hepatic Ceramide Production and Remodels Liver Fat Content

Studies have indicated that increasing plasma bilirubin levels might be useful for preventing and treating hepatic lipid accumulation that occurs with metabolic diseases such as obesity and diabetes. We have previously demonstrated that mice with hyperbilirubinemia had significantly less lipid accumulation in a diet-induced non-alcoholic fatty liver disease (NAFLD) model. However, bilirubin's effects on individual lipid species are currently unknown. Therefore, we used liquid chromatography-mass spectroscopy (LC-MS) to determine the hepatic lipid composition of obese mice with NAFLD treated with bilirubin nanoparticles or vehicle control. We placed the mice on a high-fat diet (HFD) for 24 weeks and then treated them with bilirubin nanoparticles or vehicle control for 4 weeks while maintaining the HFD. Bilirubin nanoparticles suppressed hepatic fat content overall. After analyzing the lipidomics data, we determined that bilirubin inhibited the accumulation of ceramides in the liver. The bilirubin nanoparticles significantly lowered the hepatic expression of two essential enzymes that regulate ceramide production, Sgpl1 and Degs1. Our results demonstrate that the bilirubin nanoparticles improve hepatic fat content by reducing ceramide production, remodeling the liver fat content, and improving overall metabolic health.

Suppressing Hepatic UGT1A1 Increases Plasma Bilirubin, Lowers Plasma Urobilin, Reorganizes Kinase Signaling Pathways and Lipid Species and Improves Fatty Liver Disease

Several population studies have observed lower serum bilirubin levels in patients with non-alcoholic fatty liver disease (NAFLD). Yet, treatments to target this metabolic phenotype have not been explored. Therefore, we designed an N-Acetylgalactosamine (GalNAc) labeled RNAi to target the enzyme that clears bilirubin from the blood, the UGT1A1 glucuronyl enzyme (GNUR). In this study, male C57BL/6J mice were fed a high-fat diet (HFD, 60%) for 30 weeks to induce NAFLD and were treated subcutaneously with GNUR or sham (CTRL) once weekly for six weeks while continuing the HFD. The results show that GNUR treatments significantly raised plasma bilirubin levels and reduced plasma levels of the bilirubin catabolized product, urobilin. We show that GNUR decreased liver fat content and ceramide production via lipidomics and lowered fasting blood glucose and insulin levels. We performed extensive kinase activity analyses using our PamGene PamStation kinome technology and found a reorganization of the kinase pathways and a significant decrease in inflammatory mediators with GNUR versus CTRL treatments. These results demonstrate that GNUR increases plasma bilirubin and reduces plasma urobilin, reducing NAFLD and inflammation and improving overall liver health. These data indicate that UGT1A1 antagonism might serve as a treatment for NAFLD and may improve obesity-associated comorbidities.

A cross-sectional study to correlate antioxidant enzymes, oxidative stress and inflammation with prevalence of hypertension

AIMS

Hypertension a multifactorial consequence of environmental factors, life style and genetics is the well-recognized risk factor contributing to coronary heart diseases. The antioxidant imbalance, excessive reactive oxygen species (ROS) leads to oxidative stress which is pivotal in progression of hypertension. The present study aims to understand the complex interaction between oxidative stress, inflammation and antioxidant system which is crucial to maintain cellular homeostasis which further can exaggerate hypertension pathophysiology.

MATERIALS AND METHODS

The metabolic profile of hypertensive and normotensive subjects from Malwa region, Punjab was compared by estimating lipid profile, cardiac, hepatic and renal markers. The oxidative stress markers (protein carbonyls and lipid peroxidation), inflammatory markers (Nitric oxide, Myeloperoxidase and advanced oxygen protein products), and antioxidant enzymes (Superoxide Dismutase, Catalase, and Total Antioxidant Capacity) were analyzed.

KEY FINDINGS

It is observed that the metabolic markers are altered in hypertensive subjects which further these subjects showed increased oxidative, inflammatory profile and compromised antioxidant status when compared with normotensive subjects. Co-relation analysis validated the involvement of inflammation and oxidative stress in impaired endothelial function and vital organ damage.

SIGNIFICANCE OF STUDY

These markers may act as early indicators of hypertension which usually do not show any physical symptoms, thus can be diagnosed and treated at the earliest. The current study suggests that disturbed homeostasis, a consequence of altered interaction between antioxidant system and inflammatory events raises the oxidative stress levels which eventually leads to hypertension and associated complications. These indicators can serve as early indicators of future chronic complications of hypertension.

Cutting edge concepts: Does bilirubin enhance exercise performance?

Exercise performance is dependent on many factors, such as muscular strength and endurance, cardiovascular capacity, liver health, and metabolic flexibility. Recent studies show that plasma levels of bilirubin, which has classically been viewed as a liver dysfunction biomarker, are elevated by exercise training and that elite athletes may have significantly higher levels. Other studies have shown higher plasma bilirubin levels in athletes and active individuals compared to general, sedentary populations. The reason for these adaptions is unclear, but it could be related to bilirubin's antioxidant properties in response to a large number of reactive oxygen species (ROS) that originates from mitochondria during exercise. However, the mechanisms of these are unknown. Current research has re-defined bilirubin as a metabolic hormone that interacts with nuclear receptors to drive gene transcription, which reduces body weight. Bilirubin has been shown to reduce adiposity and improve the cardiovascular system, which might be related to the adaption of bilirubin increasing during exercise. No studies have directly tested if elevating bilirubin levels can influence athletic performance. However, based on the mechanisms proposed in the present review, this seems plausible and an area to consider for future studies. Here, we discuss the importance of bilirubin and exercise and how the combination might improve metabolic health outcomes and possibly athletic performance.

Bilirubin Levels Are Negatively Correlated with Adiposity in Obese Men and Women, and Its Catabolized Product, Urobilin, Is Positively Associated with Insulin Resistance

Bilirubin levels in obese humans and rodents have been shown to be lower than in their lean counterparts. Some studies have proposed that the glucuronyl UGT1A1 enzyme that clears bilirubin from the blood increases in the liver with obesity. UGT1A1 clearance of bilirubin allows more conjugated bilirubin to enter the intestine, where it is catabolized into urobilin, which can be then absorbed via the hepatic portal vein. We hypothesized that when bilirubin levels are decreased, the urobilin increases in the plasma of obese humans, as compared to lean humans. To test this, we measured plasma levels of bilirubin and urobilin, body mass index (BMI), adiposity, blood glucose and insulin, and HOMA IR in a small cohort of obese and lean men and women. We found that bilirubin levels negatively correlated with BMI and adiposity in obese men and women, as compared to their lean counterparts. Contrarily, urobilin levels were positively associated with adiposity and BMI. Only obese women were found to be insulin resistant based on significantly higher HOMA IR, as compared to lean women. The urobilin levels were positively associated with HOMA IR in both groups, but women had a stronger linear correlation. These studies indicate that plasma urobilin levels are associated with obesity and its comorbidities, such as insulin resistance.

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.

High IgG4 serum concentration is associated with active Graves orbitopathy

BACKGROUND

The aim of the study was to evaluate the differences in clinical profile, laboratory parameters, and ophthalmological signs, and symptoms between patients with high IgG4 Graves orbitopathy and patients with normal IgG4 Graves orbitopathy.

METHODS

This was a prospective observational study. We recruited adult patients with Graves Orbitopathy(GO) referred to our clinic for further diagnostics and treatment. Eventually, 60 patients with GO were enrolled in the study. All patients underwent ophthalmological assessment, magnetic resonance imaging (MRI) of the orbits, and laboratory tests, including IgG4 serum concentration measurement. High IgG4 GO was diagnosed if the IgG4 concentration exceeded 135 mg/dl. We used both the clinical activity score (CAS) and magnetic resonance imaging (MRI) to assess the activity of GO. Eventually, active GO was defined according to MRI results.

RESULTS

Among 60 GO patients, 15 (25%) patients had elevated IgG4 levels. Patients in the high IgG4 group had a higher prevalence of active GO by MRI than patients with normal IgG4 (100% vs. 64.44%, P=0.006). They also had a higher eosinophile count in peripheral blood, a lower bilirubin level, a more frequent lower eyelid retraction, and a lower prevalence of glaucoma. There were no statistically significant differences between the groups in CAS. Patients with active GO, had higher median IgG4 level [89.95 (55.48; 171.1) vs 43.45 (32.48; 49.68) mg/dl, P<0.001]. The receiver operating characteristic (ROC) analysis for IgG4 as a marker of active GO revealed the following results: AUC 0.848 for the cut-off value of 54.2 mg/dl, sensitivity 79.5%, specificity 87.5%, positive predictive value 94.6%, negative predictive value 59.1%.

CONCLUSIONS

We demonstrated that IgG4 is a marker of GO activity. Certain differences in the clinical profile of patients with high IgG4 GO, and normal IgG4 GO were observed. More data is needed to establish whether patients with high IgG4 GO are GO patients with particularly active disease or actually represent a distinct clinical entity related to IgG4-Related Disease.