Bilirubin metabolism and its application in disease prevention: mechanisms and research advances

The role of bilirubin, a product of heme metabolism, has evolved from a traditionally perceived metabolic waste product to a critical molecule with diverse biological roles. This article comprehensively reviews the metabolic functions of bilirubin and advances in its application for disease prevention. Bilirubin is primarily derived from hemoglobin catabolism in senescent erythrocytes. It is subsequently metabolized and excreted by the liver through tightly regulated processes involving enzymes, nuclear receptors, hormones, and pharmaceuticals. Bilirubin exhibits diverse physiological functions, including antioxidant, anti-inflammatory, and immunomodulatory activities. Owing to its unique chemical structure, bilirubin scavenges free radicals, inhibits lipid peroxidation, and protects cells across multiple systems. By suppressing the NF-κB signaling pathway, it reduces inflammatory factor release and mitigates chronic inflammation. Additionally, it modulates immune cell activity to maintain homeostasis, offering therapeutic potential for autoimmune and infectious diseases. Bilirubin demonstrates significant potential in disease prevention. In cardiovascular diseases, it attenuates atherosclerosis and mitigates myocardial ischemia/reperfusion injury. For metabolic disorders, it improves insulin resistance, regulates blood glucose, and reduces hepatic steatosis, offering therapeutic benefits for diabetes and non-alcoholic fatty liver disease. In neurological conditions, its antioxidant and anti-inflammatory properties hold promise for preventing and managing neurodegenerative diseases and neonatal bilirubin encephalopathy. Although research on bilirubin has advanced significantly, its intracellular targets and molecular interaction networks remain incompletely understood, and numerous challenges hinder its clinical translation. Future efforts should leverage multi-omics technologies to elucidate its mechanisms, develop intelligent and personalized therapeutics, and conduct large-scale clinical trials to accelerate translational applications and improve patient outcomes.

Bilirubin nanotechnology: An innovative approach in biomedicine

Bilirubin, a product of heme catabolism, is toxic at elevated concentrations (>250-300 μM in blood serum), whereas at therapeutic concentrations (∼20-200 μM) exerts potent antioxidant, anti-inflammatory, immunomodulatory, cytoprotective and neuroprotective effects. Despite the therapeutic potential, its use in clinical practice is hampered by poor aqueous solubility, instability, and rapid metabolism. Nanotechnology overcomes these limitations and additionally imparts to bilirubin the advantages characteristic of nanopreparations: targeted action on the desired organ/tissue, increased therapeutic efficacy by delaying drug elimination from the body, improved transportation over biological barriers, the ability to combine therapeutic and diagnostic properties in a single agent. The review analyses the chemical synthesis, therapeutic mechanisms, and preclinical applications of nanosystems comprising bilirubin. In particular, nanostructures obtained by the covalent binding of bilirubin to macromolecules, bilirubin encapsulation in nanocarriers, bilirubin conjugation with metal nanoparticles and nanofunctionalization of inorganic compounds are considered; the data on the therapeutic trials of nanobilirubin are summarized. While studies on animal models and in vitro systems demonstrate improved biodistribution, reduced toxicity, and enhanced efficacy, no clinical trials to date have validated nanobilirubin formulations. Key barriers may include unresolved challenges in scalable synthesis, long-term biocompatibility, reproducible dosing of nanoformulations. Hence, further development of nanotherapeutic bilirubin agents for clinical practice is urgent.

Exploring new drug treatment targets for immune related bone diseases using a multi omics joint analysis strategy

In the field of treatment and prevention of immune-related bone diseases, significant challenges persist, necessitating the urgent exploration of new and effective treatment methods. However, most existing Mendelian randomization (MR) studies are confined to a single analytical approach, which limits the comprehensive understanding of the pathogenesis and potential therapeutic targets of these diseases. In light of this, we propose the hypothesis that genetic variations in specific plasma proteins have a causal relationship with immune-related bone diseases through the MR mechanism, and that key therapeutic targets can be accurately identified using an integrated multi-omic analysis approach. This study comprehensively applied a variety of analytical methods. Firstly, the protein quantitative trait locus (pQTLs) data from two large plasma protein databases and the Genome-Wide Association Study (GWAS) data of nine immune-related bone diseases were used for Mendelian randomization (MR) analysis. At the same time, we employed the Summary-based Mendelian Randomization (SMR) method, combined with the Bayesian colocalization analysis method of coding genes, as well as the Linkage Disequilibrium Score Regression (LDSC) analysis method based on genetic correlation analysis, as methods to verify the genetic association between genes and complex diseases, thus comprehensively obtaining positive results. In addition, a Phenome-wide Association Study (PheWAS) was conducted on significantly positive genes, and their expression patterns in different tissues were also explored. Subsequently, we integrated Protein-Protein Interaction (PPI) network analysis, Gene Ontology (GO) analysis. Finally, based on the above analytical methods, drug prediction and molecular docking studies were carried out with the aim of accurately identifying key therapeutic targets. Through a comprehensive analysis using four methods, namely the Mendelian randomization (MR) analysis study, Summary-based Mendelian Randomization (SMR) analysis study, Bayesian colocalization analysis study, and Linkage Disequilibrium Score Regression (LDSC) analysis study. We found that through MR, SMR, and combined with Bayesian colocalization analysis, an association was found between rheumatoid arthritis (RA) and HDGF. Using the combination of MR and Bayesian colocalization analysis, as well as LDSC analysis, it was concluded that RA was related to CCL19 and TNFRSF14. Based on the methods of MR and Bayesian colocalization, an association was found between GPT and Crohn's disease-related arthritis, and associations were found between BTN1A1, EVI5, OGA, TNFRSF14 and multiple sclerosis (MS), and associations were found between ICAM5, CCDC50, IL17RD, UBLCP1 and psoriatic arthritis (PsA). Specifically, in the MR analysis of RA, HDGF (P_ivw = 0.0338, OR = 1.0373, 95%CI = 1.0028-1.0730), CCL19 (P_ivw = 0.0004, OR = 0.3885, 95%CI = 0.2299-0.6566), TNFRSF14 (P_ivw = 0.0007, OR = 0.6947, 95%CI = 0.5634-0.8566); in the MR analysis of MS, BTN1A1 (P_ivw = 0.0000, OR = 0.6101, 95%CI = 0.4813-0.7733), EVI5 (P_ivw = 0.0000, OR = 0.3032, 95%CI = 0.1981-0.4642), OGA (P_ivw = 0.0005, OR = 0.4599, 95%CI = 0.2966-0.7131), TNFRSF14 (P_ivw = 0.0002, OR = 0.4026, 95%CI = 0.2505-0.6471); in the MR analysis of PsA, ICAM5 (P_ivw = 0.0281, OR = 1.1742, 95%CI = 1.0174-1.3552), CCDC50 (P_ivw = 0.0092, OR = 0.7359, 95%CI = 0.5843-0.9269), IL17RD (P_ivw = 0.0006, OR = 0.7887, 95%CI = 0.6886-0.9034), UBLCP1 (P_ivw = 0.0021, OR = 0.6901, 95%CI = 0.5448-0.8741); in the MR analysis of Crohn's disease-related arthritis, GPT (P_ivw = 0.0006, OR = 0.0057, 95%CI = 0.0003-0.1111). In the Bayesian colocalization analysis of RA, HDGF (H4 = 0.8426), CCL19 (H4 = 0.9762), TNFRSF14 (H4 = 0.8016); in the Bayesian colocalization analysis of MS, BTN1A1 (H4 = 0.7660), EVI5 (H4 = 0.9800), OGA (H4 = 0.8569), TNFRSF14 (H4 = 0.8904); in the Bayesian colocalization analysis of PsA, ICAM5 (H4 = 0.9476), CCDC50 (H4 = 0.9091), IL17RD (H4 = 0.9301), UBLCP1 (H4 = 0.8862); in the Bayesian colocalization analysis of Crohn's disease-related arthritis, GPT (H4 = 0.8126). In the SMR analysis of RA, HDGF (p_SMR = 0.0338, p_HEIDI = 0.0628). In the LDSC analysis of RA, CCL19 (P = 0.0000), TNFRSF14 (P = 0.0258). By comprehensively analyzing plasma proteomic and transcriptomic data, we successfully identified key therapeutic targets for various clinical subtypes of immune-associated bone diseases. Our findings indicate that the significant positive genes associated with RA include HDGF, CCL19, and TNFRSF14; the positive gene linked to Crohn-related arthropathy is GPT; for MS, the positive genes are BTN1A1, EVI5, OGA, and TNFRSF14; and for PsA, the positive genes are ICAM5, CCDC50, IL17RD, and UBLCP1. Through this comprehensive analytical approach, we have screened potential therapeutic targets for different clinical subtypes of immune-related bone diseases. This research not only enhances our understanding of the pathogenesis of these conditions but also provides a solid theoretical foundation for subsequent drug development and clinical treatment, with the potential to yield significant advancements in the management of patients with immune-related bone diseases.

Unraveling the dual role of bilirubin in neurological Diseases: A Comprehensive exploration of its neuroprotective and neurotoxic effects

Neurodegenerative disorders are characterized by a progressive loss of neurons, causing substantial deficits in motor and cognitive functioning. Bilirubin is a yellow by-product of heme, existing in two primary isoforms namely unconjugated and conjugated, while initially produced unconjugated isomer is lipophilic and cytotoxic in nature. At physiological levels, bilirubin has an important role in brain function by acting as a powerful antioxidant, preventing brain tissues from oxidative damage by eliminating reactive oxygen species (ROS). Additionally, it contributes to immune regulation through microglial activation, cytokine release, complement system interception, fragment crystallization (Fc) receptor modulation, and major histocompatibility complex (MHC II) expression modification, which lower the risk of inflammatory and autoimmune reactions in the central nervous system (CNS). As per the literature, serum bilirubin concentrations are associated with CNS diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), ischemic stroke, hemorrhagic stroke, traumatic brain injury (TBI), multiple sclerosis (MS), epilepsy, schizophrenia and kernicterus spectrum disorder (KSD), which causes neuronal damage, especially in regions like the basal ganglia and cerebellum, which causes movement abnormalities and cognitive deficits. The aim of this article is to explore the dual role of bilirubin as neuroprotective and neurotoxic, essential for establishing effective therapeutic outcomes for neurodegenerative diseases by looking at its cellular mechanisms and discussing how bilirubin's antioxidant properties can shield neurons and, in some situations, may induce oxidative stress and apoptosis.

Self-assembled HO-1i-Pt(IV) nanomedicine targeting p38/MAPK and MDR pathways for cancer chemo-immunotherapy

Platinum(II)-based antitumor drugs are widely used in clinics but limited by severe side effects and resistance. Multi-target Platinum(IV) complexes are emerging as ideal alternatives. Heme oxygenase-1 (HO-1) works as a rate-limiting step in heme degradation and is overexpressed in malignant tumors. Herein, HO-1i-based Platinum(IV) prodrugs are prepared and candidate complex 15 is further developed into self-assembled nanoparticles (15-NPs). 15 and 15-NPs significantly increase cytotoxicity, particularly in HepG2 (74.77- and 96.14-fold increases) and A549cisR (38.6- and 47.24-fold increases), while reducing toxicity towards normal cells compared to cisplatin. In vitro experiments show 15 and 15-NPs activated multiple pathways, including p38/MAPK- and MDR-related proteins, achieving multi-target synergistic chemosensitization and anti-resistance, further verified by RNA-sequencing analysis. In vivo tests demonstrate that 15 and 15-NPs efficiently inhibit tumor growth and systemic toxicity, especially 15-NPs with optimal tumor-inhibition rate and survival (80% and 100%), superior to cisplatin (40% and 50%), attributing to its extra endocytosis, EPR effect, and precisely tumor-targeted release besides the advantage of a free HO-1i-Pt(IV) prodrug. Additionally, 15 and 15-NPs distinctly regulate T-cell and macrophage functions, thereby exhibiting a chemoimmuno-combined action. This study highlights that multi-functional Platinum(IV) prodrug target-delivered to tumors via carrier-free nanoparticles may represent an effective modality for improving cancer therapy.

Bilirubin: Photophysical and photochemical properties, phototherapy, analytical methods of measurement. A short review

Bilirubin, a yellow bile pigment, plays an important role in the body, being a potent antioxidant and having anti-inflammatory, immunomodulatory, cytoprotective, and neuroprotective functions. This makes bilirubin promising as a therapeutic and diagnostic agent in biomedicine. However, excess bilirubin is toxic and should be removed from the body. Bilirubin exhibits photochemical activity, which has been the subject of numerous studies up to now. Such studies are relevant because the bilirubin photochemistry provides the basis for bilirubin removing in phototherapy of neonatal jaundice (neonatal hyperbilirubinemia) and for some therapeutic applications. Furthermore, it can model several elementary processes of molecular photonics. In particular, the bilirubin molecule is capable of ultrafast Z-E photoisomerization and contains two almost identical dipyrromethenone chromophores capable of exciton coupling. The present review considers the data on the photophysical and photochemical properties of bilirubin and ultrafast routes of its phototransformations, as well as its photochemical reactions in phototherapy of neonatal hyperbilirubinemia and the ways to decrease the possible adverse effects of the phototherapy. The main analytical methods of bilirubin measurement in biological systems are also viewed.

The Heme Oxygenase/Biliverdin Reductase System and Its Genetic Variants in Physiology and Diseases

Heme oxygenase (HO) metabolizes heme into ferrous iron, carbon monoxide (CO), and biliverdin-IXα (BV), the latter being reduced into bilirubin-IXα (BR) by the biliverdin reductase-A (BVR). Heme oxygenase exists as two isoforms, HO-1, inducible and involved in the cell stress response, and HO-2, constitutive and committed to the physiologic turnover of heme and in the intracellular oxygen sensing. Many studies have identified genetic variants of the HO/BVR system and suggested their connection in free radical-induced diseases. The most common genetic variants include (GT)n dinucleotide length polymorphisms and single nucleotide polymorphisms. Gain-of-function mutations in the HO-1 and HO-2 genes foster the ventilator response to hypoxia and reduce the risk of coronary heart disease and age-related macular degeneration but increase the risk of neonatal jaundice, sickle cell disease, and Parkinson's disease. Conversely, loss-of-function mutations in the HO-1 gene increase the risk of type 2 diabetes mellitus, chronic obstructive pulmonary disease, and some types of cancers. Regarding BVR, the reported loss-of-function mutations increase the risk of green jaundice. Unfortunately, the physiological role of the HO/BVR system does not allow for the hypothesis gene silencing/induction strategies, but knowledge of these mutations can certainly facilitate a medical approach that enables early diagnoses and tailored treatments.

Causal effects of genetically determined circulating metabolites on endometriosis: A Mendelian randomization study

Endometriosis (EMs) is a common gynecological disease accompanied by metabolic disturbances. However, the causality between metabolites and the risk of EMs remains unclear. We conducted a 2-sample Mendelian randomization (MR) analysis using the publicly available genome-wide association study (GWAS) of 486 circulating metabolites and EMs. The inverse variance weighted (IVW) was mainly used for assessing causality. MR-Egger intercept, MR-PRESSO Global, leave-one-out, and Cochran Q test analyses were used for sensitivity analyses. A total of 25 causal metabolites related to EMs have been identified, including 13 known and 12 unknown ones. Among the known metabolites, caffeine (OR = 0.86, 95% CI: 0.76-0.98, P = .026), cortisol (OR = 0.64, 95% CI: 0.41-0.99, P = .047), glycocholate (OR = 0.67, 95% CI: 0.51-0.87, P = .003), adrenate 22:4n6 (OR = 0.52, 95% CI: 0.35-0.77, P = .001), and ergothioneine (OR = 0.62, 95% CI: 0.47-0.81, P = .000) were protective factors for EMs, while mannose (OR = 1.43, 95% CI: 1.01-2.03, P = .044), 4-acetamidobutanoate (OR = 1.92, 95% CI: 1.27-2.89, P = .002), 1-linoleoylglycerol (OR = 1.36, 95% CI: 1.10-1.68, P = .005), bilirubin (Z, Z) (OR = 1.15, 95% CI: 1.01-1.31, P = .032), threonate (OR = 1.42, 95% CI: 1.14-1.77, P = .002), bilirubin (E, E) (OR = 1.18, 95% CI: 1.01-1.38, P = .039), erythronate (OR = 1.59, 95% CI: 1.01-2.52, P = .047), and dimethylarginine (SDMA + ADMA) (OR = 2.07, 95% CI: 1.19-3.62, P = .010) were risk factors for EMs. Additionally, there was no evidence of heterogeneity or pleiotropy of the known metabolites. Leave-one-out analysis indicated that the MR findings were robust. Our findings provide valuable circulating biomarkers as well as therapeutic targets for the screening, prevention, and treatment of EMs.

Heme catabolism and heme oxygenase-1-expressing myeloid cells in pathophysiology

Although the pathological significance of myeloid cell heterogeneity is still poorly understood, new evidence indicates that distinct macrophage subsets are characterized by specific metabolic programs that influence disease onset and progression. Within this scenario, distinct subsets of macrophages, endowed with high rates of heme catabolism by the stress-responsive enzyme heme oxygenase-1 (HO-1), play critical roles in physiologic and pathological conditions. Of relevance, the substrates of HO-1 activity are the heme groups that derive from cellular catabolism and are converted into carbon monoxide (CO), biliverdin and Fe2+, which together elicit anti-apoptotic, anti-inflammatory activities and control oxidative damage. While high levels of expression of HO-1 enzyme by specialized macrophage populations (erythrophagocytes) guarantee the physiological disposal of senescent red blood cells (i.e. erythrocateresis), the action of HO-1 takes on pathological significance in various diseases, and abnormal CO metabolism has been observed in cancer, hematological diseases, hypertension, heart failure, inflammation, sepsis, neurodegeneration. Modulation of heme catabolism and CO production is therefore a feasible therapeutic opportunity in various diseases. In this review we discuss the role of HO-1 in different pathological contexts (i.e. cancer, infections, cardiovascular, immune-mediated and neurodegenerative diseases) and highlight new therapeutic perspectives on the modulation of the enzymatic activity of HO-1.

Antioxidant Therapies in the Treatment of Multiple Sclerosis

Several studies have proposed a potential role for oxidative stress in the development of multiple sclerosis (MS). For this reason, it seems tentative to think that treatment with antioxidant substances could be useful in the treatment of this disease. In this narrative review, we provide a summary of the current findings on antioxidant treatments, both in experimental models of MS, especially in experimental autoimmune encephalomyelitis (EAE) and in the cuprizone-induced demyelination model, and clinical trials in patients diagnosed with MS. Practically all the antioxidants tested in experimental models of MS have shown improvement in clinical parameters, in delaying the evolution of the disease, and in improving histological and biochemical parameters, including decreased levels of markers of inflammation and oxidative stress in the central nervous system and other tissues. Only a few clinical trials have been carried out to investigate the potential efficacy of antioxidant substances in patients with MS, most of them in the short term and involving a short series of patients, so the results of these should be considered inconclusive. In this regard, it would be desirable to design long-term, randomized, multicenter clinical trials with a long series of patients, assessing several antioxidants that have demonstrated efficacy in experimental models of MS.

Aryl hydrocarbon receptor: current perspectives on key signaling partners and immunoregulatory role in inflammatory diseases

The aryl hydrocarbon receptor (AhR) is a versatile environmental sensor and transcription factor found throughout the body, responding to a wide range of small molecules originating from the environment, our diets, host microbiomes, and internal metabolic processes. Increasing evidence highlights AhR's role as a critical regulator of numerous biological functions, such as cellular differentiation, immune response, metabolism, and even tumor formation. Typically located in the cytoplasm, AhR moves to the nucleus upon activation by an agonist where it partners with either the aryl hydrocarbon receptor nuclear translocator (ARNT) or hypoxia-inducible factor 1β (HIF-1β). This complex then interacts with xenobiotic response elements (XREs) to control the expression of key genes. AhR is notably present in various crucial immune cells, and recent research underscores its significant impact on both innate and adaptive immunity. This review delves into the latest insights on AhR's structure, activating ligands, and its multifaceted roles. We explore the sophisticated molecular pathways through which AhR influences immune and lymphoid cells, emphasizing its emerging importance in managing inflammatory diseases. Furthermore, we discuss the exciting potential of developing targeted therapies that modulate AhR activity, opening new avenues for medical intervention in immune-related conditions.

Reactive Oxygen Species-Responsive Delivery of a Notch Inhibitor to Alleviate Nonalcoholic Steatohepatitis by Inhibiting Hepatic de Novo Lipogenesis and Inflammation

With the increased prevalence of nonalcoholic steatohepatitis (NASH) in the world, effective pharmacotherapy in clinical practice is still lacking. Previous studies have shown that dibenzazepine (DBZ), a Notch inhibitor, could alleviate NASH development in a mouse model. However, low bioavailability, poor water solubility, and extrahepatic side effects restrict its clinical application. To overcome these barriers, we developed a reactive oxygen species (ROS)-sensitive nanoparticle based on the conjugation of bilirubin to poly(ethylene glycol) (PEG) chains, taking into account the overaccumulation of hepatic ROS in the pathologic state of nonalcoholic steatohepatitis (NASH). The PEGylated bilirubin can self-assemble into nanoparticles in an aqueous solution and encapsulate insoluble DBZ into its hydrophobic cavity. DBZ nanoparticles (DBZ Nps) had good stability, rapidly released DBZ in response to H2O2, and effectively scavenged intracellular ROS of hepatocytes. After systemic administration, DBZ Nps could accumulate in the liver of the NASH mice, extend persistence in circulation, and improve the bioavailability of DBZ. Furthermore, DBZ Nps significantly improved glucose intolerance, relieved hepatic lipid accumulation and inflammation, and ameliorated NASH-induced liver fibrosis. Additionally, DBZ Nps had no significant extrahepatic side effects. Taken together, our results highlight the potential of the ROS-sensitive DBZ nanoparticle as a promising therapeutic strategy for NASH.

Clinical Significance of Albumin-Bilirubin Grade in Thoracic Esophageal Squamous Cell Carcinoma

INTRODUCTION

The albumin-bilirubin (ALBI) score evaluates liver dysfunction severity. However, this score had prognostic effects in patients with hepatocellular, pancreatic, and gastric carcinomas. We aimed to assess the predictive value of the ALBI score in patients with esophageal squamous cell carcinoma (ESCC).

METHODS

Data from 154 patients with ESCC who consecutively underwent neoadjuvant chemotherapy (NAC) and subtotal esophagectomy were retrospectively investigated. The ALBI score was calculated as pre-NAC ALBI and categorized into grades 1, 2a, 2b, and 3; low-ALBI group (n = 134) was assigned with ALBI grade 1 and the other grades were assigned to the high-ALBI group (n = 20).

RESULTS

The pre-NAC ALBI was significantly associated with relapse-free survival (RFS) and overall survival (P = 0.003 and P = 0.014, respectively). Based on multivariate analysis, pre-NAC ALBI, pathological T factor, and N factor were identified as independent prognostic factors for poor RFS. Multivariate and univariate analyses limited to factors were obtained before treatment, indicating high pre-NAC ALBI as an independent prognostic factor of poor overall survival (P = 0.039) and RFS (P = 0.008). With respect to pathological response to NAC, patients in the high pre-NAC ALBI group had a significantly lower response than patients in the low pre-NAC ALBI group (P = 0.010).

CONCLUSIONS

Our results suggested that the pre-NAC ALBI marker predicts the long-term outcome and pathological response to NAC in patients with ESCC consecutively undergoing NAC and a subtotal esophagectomy.

Causal inference between serum bilirubin levels and juvenile idiopathic arthritis-associated uveitis: A bidirectional Mendelian randomization study

Background

Several observational studies have suggested an association between low serum bilirubin levels and Behçet's disease uveitis. However, the causal inference between bilirubin level and juvenile idiopathic arthritis-associated uveitis (JIAU) remains ambiguous. We investigated the potential causal relationship between serum bilirubin levels and JIAU using a bidirectional two-sample Mendelian randomization (MR) framework.

Methods

We systemically integrated summary-level data from published large-scale genome-wide association studies on bilirubin level and JIAU in a Caucasian British population. To determine the causal effect of bilirubin level on JIAU, we constructed strong instrumental variables using 47 and 80 single-nucleotide polymorphisms (SNPs) specific to direct bilirubin and total bilirubin levels, respectively. For reverse causal inference, seven SNPs associated with JIAU were included in our study. Multiple complementary methods were further performed to evaluate the robustness of MR estimates.

Results

The inverse-variance weighted estimate did not show any significant causal associations of genetically predicted serum direct or total bilirubin level with the risk of JIAU (odds ratio [OR]: 1.010, 95% confidence interval [CI]: 0.750-1.359, p = 0.947; OR: 0.867, 95% CI: 0.688-1.093; p = 0.227, respectively). MR-Egger and weighted median methods also obtained similar associations. Additionally, the results of reverse MR analyses using JIAU as exposure showed no associations of genetically predicted risk of JIAU with serum bilirubin levels (p > 0.05). In sensitivity analysis, the causal estimate between serum bilirubin levels and JIAU did not differ when SNPs associated with possible confounders were omitted.

Conclusion

Genetic evidence from our bidirectional analysis did not support a causal association between serum bilirubin levels and JIAU risk in the Caucasian British population. Future large-scale studies should be conducted to validate these findings and explore any causal effects on the disease process.

Interorgan communication with the liver: novel mechanisms and therapeutic targets

The liver is a multifunctional organ that plays crucial roles in numerous physiological processes, such as production of bile and proteins for blood plasma, regulation of blood levels of amino acids, processing of hemoglobin, clearance of metabolic waste, maintenance of glucose, etc. Therefore, the liver is essential for the homeostasis of organisms. With the development of research on the liver, there is growing concern about its effect on immune cells of innate and adaptive immunity. For example, the liver regulates the proliferation, differentiation, and effector functions of immune cells through various secreted proteins (also known as "hepatokines"). As a result, the liver is identified as an important regulator of the immune system. Furthermore, many diseases resulting from immune disorders are thought to be related to the dysfunction of the liver, including systemic lupus erythematosus, multiple sclerosis, and heart failure. Thus, the liver plays a role in remote immune regulation and is intricately linked with systemic immunity. This review provides a comprehensive overview of the liver remote regulation of the body's innate and adaptive immunity regarding to main areas: immune-related molecules secreted by the liver and the liver-resident cells. Additionally, we assessed the influence of the liver on various facets of systemic immune-related diseases, offering insights into the clinical application of target therapies for liver immune regulation, as well as future developmental trends.

Albumin-Bilirubin (ALBI) Score and Systemic Immune-Inflammation Indexes Used As Pretreatment Outcome Predictors in Patients With Pancreatic Ductal Adenocarcinoma Undergoing Robotic or Open Whipple Procedures: A Logistic Regression Analysis

Background Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer (PC) in the United States. In patients with resectable PC, identification of pretreatment biomarkers before surgery can help in the decision-making process by weighing the benefits of neo-adjuvant therapy, surgical procedure, and adjuvant therapy. The purpose of this study was to determine if the albumin-bilirubin (ALBI) score and immune-inflammatory marker levels can be used in combination as pretreatment predictors of mortality risk in patients undergoing the Whipple procedure (alternatively, pancreatoduodenectomy (PD)) for PDAC. Methods This retrospective study included 115 patients with PDAC who underwent open or robotic Whipple procedures between January 2013 and December 2022 at a single tertiary medical center. Logistic regression analysis was used to find the association between predictors and mortality. Machine learning algorithms were used to calculate the performance of the different models. Results Bivariate analysis showed that the variables "sex" and "body mass index (BMI)" had a potential association with mortality, although statistical significance was not achieved for sex (p = 0.07). Patients with BMIs >25 kg/m2 had a higher risk of mortality compared to patients with BMIs ≤24.9 kg/m2 (odds ratio (OR) = 2.2, 95% CI = 1.03-4.8, p = 0.04). Higher (more positive) ALBI scores (>-2.24) were also associated with increased mortality risk (OR = 4.6, 95% CI = 2-10.5, p = 0.0003). When the cutoff values of the inflammatory markers were used to categorize these variables, values greater than the cutoff values were associated with an increased risk of mortality. In the multivariate logistic regression model, an ALBI score >-2.24 (OR = 4.3, 95% CI = 1.8-10.3, p = 0.0008), neutrophil-to-lymphocyte ratio (NLR) >3.5 (OR = 3.3, 95% CI = 1.4-7.9, p = 0.007), and being a woman (OR = 2.6, 95% CI = 1.1-6.4, p = 0.03) remained influential predictors of increased mortality (c value = 0.77). Conclusion The ALBI score and the NLR are easily accessible markers; their use, combined with a patient's sex, can provide useful pre-surgical information regarding mortality risk after PD. This can aid in treatment planning as well as expedite decisions about the type of Whipple procedure, adjuvant therapy, and surveillance, which can subsequently improve a patient's outcomes and survival.

Factors influencing the degree of disability in patients with neuromyelitis optica spectrum disorders

OBJECTIVE

To investigate the factors influencing the degree of disability in patients with neuromyelitis optica spectrum disorder (NMOSD) and provide evidence for disease monitoring and clinical intervention.

METHODS

Eighty-four patients with NMOSD at Xuanwu Hospital Capital Medical University were enrolled in this retrospective study. Before treatment, blood was collected from all patients, and their expanded disability status scores were assessed.

RESULTS

Of the 84 patients assessed, 66 (78.57%) had an expanded disability status scale score < 7, and 18 (21.43%) had scores ≥ 7. The univariate analysis showed that the total bilirubin (TBil), cerebrospinal fluid albumin (CSF ALB), cerebrospinal fluid immunoglobulin G (CSF IgG), QALB, and QIgG levels in the group with scores ≥ 7 were significantly different from those with scores < 7 (P < 0.05). In addition, Spearman's correlation analysis showed a significant correlation between ALB and expanded disability status scores in patients with NMOSD (P < 0.05), and the multivariate logistic regression analysis showed that TBil was an independent factor influencing the degree of disability in patients with NMOSD (P < 0.05). The receiver operating characteristic curve was constructed using TBil values; the area under the curve of TBil was 0.729 (P < 0.01), and the best cut-off value was 11.015 g/L. Its sensitivity in predicting the severity of disability in NMOSD patients was 51.5% while its specificity was 88.9%.

CONCLUSION

TBil is an independent factor that influences the severity of disability in patients with NMOSD. In addition, ALB is closely related to NMOSD severity, and some factors associated with the BBB are significantly increased in severely disabled NMOSD patients.

Biliverdin as a disease-modifying agent: An integrated viewpoint

Biliverdin is one of the three by-products of heme oxygenase (HO) activity, the others being ferrous iron and carbon monoxide. Under physiological conditions, once formed in the cell, BV is reduced to bilirubin (BR) by the biliverdin reductase (BVR). However, if BVR is inhibited by either genetic variants, as occurs in the Inuit ethnicity, or dioxin intoxication, BV accumulates in cells giving rise to a clinical syndrome known as green jaundice. Preclinical studies have demonstrated that BV not only has a direct antioxidant effect by scavenging free radicals, but also targets many signal transduction pathways, such as BVR, soluble guanylyl cyclase, and the aryl hydrocarbon receptor. Through these direct and indirect mechanisms, BV has shown beneficial roles in ischemia/reperfusion-related diseases, inflammatory diseases, graft-versus-host disease, viral infections and cancer. Unfortunately, no clinical data are available to confirm these potential therapeutic effects and the kinetics of exogenous BV in humans is unknown. These limitations have so far excluded the possibility of transforming BV from a mere by-product of heme degradation into a disease-modifying agent. A closer collaboration between basic and clinical researchers would be advantageous to overcome these issues and promote translational research on BV in free radical-induced diseases.

Prognostic significance of pre-treatment albumin-bilirubin grade in metastatic urothelial carcinoma receiving pembrolizumab

BACKGROUND

Pre-treatment albumin-bilirubin grade is a useful biomarker for predicting prognosis in patients receiving immune checkpoint inhibitors for advanced malignancies. We evaluated the prognostic impact of pre-treatment albumin-bilirubin grade in patients receiving pembrolizumab for metastatic urothelial carcinoma.

METHODS

In this multicenter retrospective study, we calculated pre-treatment albumin-bilirubin scores of 96 patients who received pembrolizumab for metastatic urothelial carcinoma between January 2018 and March 2022. Patients were classified according to albumin-bilirubin grade. Progression-free survival and cancer-specific survival were compared between the groups. To evaluate the prognostic impact of pre-treatment albumin-bilirubin grade, we also performed Cox proportional regression analyses for progression-free survival and cancer-specific survival.

RESULTS

The median pre-treatment albumin bilirubin score was -2.52 (quartile: -2.76 to -2.10), and albumin-bilirubin grade was grade 1 in 37 patients (39%), grade 2a in 30 patients (31%), 2b in 22 patients (23%) and grade 3 in 7 patients (7%). The median progression-free survival and cancer-specific survival were 2 and 7 months, respectively. Progression-free survival and cancer-specific survival were significantly different between the albumin-bilirubin grade groups (P < 0.01 and P < 0.01, respectively) and prognosis became poorer as albumin-bilirubin grade increased. High albumin-bilirubin grade was shown in multivariable Cox proportional analyses to be independently associated with both poor progression-free survival and poor cancer-specific survival.

CONCLUSIONS

High pre-treatment albumin-bilirubin grade could be a significant independent predictor of poor prognosis in patients receiving pembrolizumab for advanced urothelial carcinoma.

Endogenous and Exogenous Antioxidants as Agents Preventing the Negative Effects of Contrast Media (Contrast-Induced Nephropathy)

The use of conventional contrast media for diagnostic purposes (in particular, Gd-containing and iodinated agents) causes a large number of complications, the most common of which is contrast-induced nephropathy. It has been shown that after exposure to contrast agents, oxidative stress often occurs in patients, especially in people suffering from various diseases. Antioxidants in the human body can diminish the pathological consequences of the use of contrast media by suppressing oxidative stress. This review considers the research studies on the role of antioxidants in preventing the negative consequences of the use of contrast agents in diagnostics (mainly contrast-induced nephropathy) and the clinical trials of different antioxidant drugs against contrast-induced nephropathy. Composite antioxidant/contrast systems as theranostic agents are also considered.

Correlation between hyperbilirubinemia risk and immune cell mitochondria parameters in neonates with jaundice

Purpose

To explore the correlation between mitochondria parameters of immune cells and hyperbilirubinemia risk in hospitalized neonates with jaundice.

Methods

This retrospective study included jaundiced neonates born between September 2020 and March 2022 at Shaoxing Keqiao Women & Children's Hospital. The neonates were divided into low, intermediate-low, intermediate-high, and high-risk groups according to the hyperbilirubinemia risk. The purpose parameters including percentage, absolute count, mitochondrial mass (MM), and single-cell MM (SCMM) of peripheral blood T lymphocytes detected by flow cytometry were collected.

Results

Finally, 162 neonates with jaundice (47, 41, 39, and 35 with low, intermediate-low, intermediate-high, and high-risk) were included. CD3⁺ SCMM was significantly higher in the high-risk group compared with the low and intermediate-low-risk groups (both P < 0.0083), CD4⁺ SCMM was significantly higher in the high-risk group compared with the three other groups (all P < 0.0083), and CD8⁺ SCMM was significantly higher in the intermediate-low and high-risk groups compared with the low-risk group (both P < 0.0083). CD3⁺ (r = 0.34, P < 0.001) and CD4⁺ (r = 0.20, P = 0.010) SCMM positively correlated with bilirubin levels.

Conclusions

The mitochondrial SCMM parameters differed significantly among jaundiced neonates with different hyperbilirubinemia risks. CD3⁺ and CD4⁺ T cell SCMM values were positively correlated with the serum bilirubin levels, and might correlated with hyperbilirubinemia risk.

Clinical Utility of the Neutrophil-to-Bilirubin Ratio in the Detection of Disease Activity in Ulcerative Colitis

Background

Ulcerative colitis (UC) is a chronic relapsing remitting form of inflammatory bowel disease (IBD). Current disease monitoring includes evaluation of symptoms, fecal calprotectin, and colonoscopy. Due to limited availability of the latter two modalities in China, we sought a readily available, inexpensive, disease monitoring laboratory assessment. We recently identified a novel serological index (the neutrophil-to-bilirubin ratio, NBR) for monitoring disease activity in Crohn's disease. However, the clinical significance has not been evaluated in UC. Here, we aimed to verify the hypothesis that NBR might be useful in monitoring clinical and endoscopic activity in patients with UC.

Methods

To test our hypothesis, we conducted a single-center, retrospective study including a total of 188 patients with UC and 145 non-IBD controls. NBR was calculated to determine its practical value in monitoring disease activity (including clinical and endoscopic activity). Disease activity of UC was determined by the partial Mayo score and the Mayo endoscopic score (MES) system.

Results

NBR was significantly higher in patients with UC than that in controls (12.10, IQR: 9.85-16.69 versus 5.06, IQR: 3.94-6.55; p < 0.001) and showed positive correlations with clinical and endoscopic disease activity in UC. Additionally, NBR was significantly lower in patients with endoscopic mucosal healing (MH) than that in those without endoscopic MH (8.81, IQR: 6.67-11.67 versus 13.51, IQR: 11.04-18.71; p < 0.001). Serial evaluation of NBR in a subset of patients demonstrated that NBR was significantly decreased during the MH stage compared with that during the endoscopically active stage.

Conclusion

Our study suggests that NBR may be a promising candidate for assessing disease activity in UC, with potential for widespread clinical use and significant clinical implications.

Toward nanotechnology-enabled application of bilirubin in the treatment and diagnosis of various civilization diseases

Bilirubin, an open chain tetrapyrrole, has powerful antioxidant, anti-inflammatory, immuno-suppressive, metabolic-modulating and anti-proliferative activities. Bilirubin is a natural molecule that is produced and metabolized within the human body, making it highly biocompatible and well suited for clinical use. However, the use of bilirubin has been hampered by its poor water solubility and instability. With advanced construction strategies, bilirubin-derived nanoparticles (BRNPs) have not only overcome the disadvantages of bilirubin but also enhanced its therapeutic effects by targeting damaged tissues, passing through physiological barriers, and ensuring controlled sustained release. We review the mechanisms underlying the biological activities of bilirubin, BRNP preparation strategies and BRNP applications in various disease models. Based on their superior performance, BRNPs require further exploration of their efficacy, biodistribution and long-term biosafety in nonhuman primate models that recapitulate human disease to promote their clinical translation.

The aryl hydrocarbon receptor in immune regulation and autoimmune pathogenesis

As a ligand-activated transcription factor, the aryl hydrocarbon receptor (AhR) is activated by structurally diverse ligands derived from the environment, diet, microorganisms, and metabolic activity. Recent studies have demonstrated that AhR plays a key role in modulating both innate and adaptive immune responses. Moreover, AhR regulates innate immune and lymphoid cell differentiation and function, which is involved in autoimmune pathogenesis. In this review, we discuss recent advances in understanding the mechanism of activation of AhR and its mediated functional regulation in various innate immune and lymphoid cell populations, as well as the immune-regulatory effect of AhR in the development of autoimmune diseases. In addition, we highlight the identification of AhR agonists and antagonists that may serve as potential therapeutic targets for the treatment of autoimmune disorders.

Blood unconjugated bilirubin and tacrolimus are negative predictors of specific cellular immunity in kidney transplant recipients after SAR-CoV-2 inactivated vaccination

The immunogenicity of SARS-CoV-2 vaccines is poor in kidney transplant recipients (KTRs). The factors related to poor immunogenicity to vaccination in KTRs are not well defined. Here, observational study demonstrated no severe adverse effects were observed in KTRs and healthy participants (HPs) after first or second dose of SARS-CoV-2 inactivated vaccine. Different from HPs with excellent immunity against SARS-CoV-2, IgG antibodies against S1 subunit of spike protein, receptor-binding domain, and nucleocapsid protein were not effectively induced in a majority of KTRs after the second dose of inactivated vaccine. Specific T cell immunity response was detectable in 40% KTRs after the second dose of inactivated vaccine. KTRs who developed specific T cell immunity were more likely to be female, and have lower levels of total bilirubin, unconjugated bilirubin, and blood tacrolimus concentrations. Multivariate logistic regression analysis found that blood unconjugated bilirubin and tacrolimus concentration were significantly negatively associated with SARS-CoV-2 specific T cell immunity response in KTRs. Altogether, these data suggest compared to humoral immunity, SARS-CoV-2 specific T cell immunity response are more likely to be induced in KTRs after administration of inactivated vaccine. Reduction of unconjugated bilirubin and tacrolimus concentration might benefit specific cellular immunity response in KTRs following vaccination.

Evaluation of Pretreatment Albumin-Bilirubin Grade as a Better Prognostic Factor Compared to Child-Pugh Classification in Patients with Hepatocellular Carcinoma Receiving Transarterial Chemoembolization Combined with Radiotherapy

This study assessed the use of pretreatment albumin--bilirubin (ALBI) grade as a prognostic factor in patients with hepatocellular carcinoma (HCC) receiving combined transarterial chemoembolization (TACE) and radiotherapy (RT). Patients who underwent RT following TACE between January 2011 and December 2020 were analyzed retrospectively. The survival outcomes of patients in regard to the ALBI grade and Child-Pugh (C-P) classification were evaluated. A total of 73 patients with a median follow-up of 16.3 months were included. Thirty-three (45.2%) and forty patients (54.8%) were categorized into ALBI grades 1 and 2-3, respectively, while sixty-four (87.7%) and nine (12.3%) were C-P classes A and B, respectively (p = 0.003). The median progression-free survival (PFS) and overall survival (OS) for ALBI grade 1 vs. 2-3 were 8.6 months vs. 5.0 months (p = 0.016) and 27.0 months vs. 15.9 months (p = 0.006), respectively. The median PFS and OS for C-P class A vs. B were 6.3 months vs. 6.1 months (p = 0.265) and 24.8 months vs. 19.0 months (p = 0.630), respectively. A multivariate analysis showed that ALBI grades 2-3 were significantly associated with worse PFS (p = 0.035) and OS (p = 0.021). In conclusion, the ALBI grade could be a good prognosticator in HCC patients who were treated with combined TACE-RT.

Heme oxygenase-1 deficiency as an extremely rare cause of AA-type renal amyloidosis: Expanding the clinical features and review of the literature

Heme oxygenase-1 (HMOX-1) is an enzyme that regulates heme degradation. Antiinflammatory, antioxidant, and cytoprotective effects of HMOX-1 were also described. It is encoded by the HMOX1 gene, and biallelic mutations cause HMOX-1 deficiency, which is a rare chronic multisystemic inflammatory disorder. This inflammatory status could lead to the development of secondary AA-type amyloidosis theoretically. Here, we report a 30-year-old male with AA-type renal amyloidosis due to a chronic inflammatory condition of unknown origin. Paternal consanguinity and dysmorphic features raised suspicion of a rare genetic disorder. Clinical exome sequencing (CES) confirmed the HMOX-1 deficiency diagnosis related to homozygous missense G139V mutation. To the best of our knowledge, our patient is the eleventh HMOX-1 deficiency case in the literature. Also, HMOX-1 deficiency-related systemic AA-type amyloidosis has not been reported before.

Preoperative controlling nutritional status score predicts systemic disease recurrence in patients with resectable biliary tract cancer

INTRODUCTION

This study aimed to evaluate the association between the preoperative Controlling Nutritional Status (CONUT) score, survival outcomes, and recurrence pattern in patients with resectable biliary tract cancer (BTC).

METHODS

A total of 224 BTC patients (gallbladder, n = 69; intrahepatic bile ducts, n = 26; perihilar bile ducts, n = 72; distal bile duct, n = 57) who underwent surgery with curative intent were enrolled. The best cutoff point of the preoperative CONUT score in discriminating survival was determined using χ2 scores. The sites of recurrence were subclassified as locoregional or distant.

RESULTS

Patients were subdivided into the CONUT-low (score ≤ 3, n = 156) and the CONUT-high (score > 3; n = 68) groups. In-hospital mortality occurred more frequently in the CONUT-high group than in the CONUT-low group (7.4% vs. 1.3%; p = 0.028). A high preoperative CONUT score was independently associated with worse overall survival (hazard ratio [HR] 1.906, p = 0.001), worse disease-specific survival (HR 1.840, p = 0.006), and worse recurrence-free survival (HR 1.680, p = 0.005). Recurrence developed in 110 (49.1%) patients. A high preoperative CONUT score was independently associated with a higher risk of distant recurrence (HR 2.245, p = 0.001), but not locoregional recurrence. The incidences of distant recurrence at 5 years were 55.4% and 34.2% in the CONUT-high and CONUT-low groups, respectively (p = 0.001).

CONCLUSIONS

The preoperative CONUT score independently predicts survival outcomes and may serve as a surrogate marker of aggressive systemic disease recurrence in patients with resectable BTC.

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.

Effects of Midazolam on Antioxidant Levels, Biochemical and Metabolic Parameters in Eurygaster integriceps Puton (Hemiptera: Scutelleridae) Eggs Parasitized by Trissolcus semistriatus Nees (Hymenoptera: Scelionidae)

Eurygaster integriceps Puton (Hemiptera: Scutelleridae) is among the most important insect pests of wheat (Triticum sativum L.) and barley (Hordeum vulgare L.) grown in the Middle East. Biological and chemical methods are insufficient to control E. integriceps populations below economic thresholds. In this study, we investigated the effects of midazolam, a clinical drug, on selected metabolic enzyme activity, antioxidant levels, and biochemical parameters in E. integriceps eggs parasitized by Trissolcus semistriatus Nees (Hymenoptera: Scelionidae). Increasing concentrations of midazolam caused cell damage in the parasitized eggs due to its oxidative effects. Transferase enzymes, such as, aspartate transferase, alanine transferase, and gamma glutamyl transferase activities were altered following exposure. Metabolic enzymes, such as, creatine kinase, alkaline phosphatase, amylase, and lactate dehydrogenase also were adversely affected. Levels of the non-enzymatic antioxidants uric acid, bilirubin, and albumin also were altered.

Pharmaceutical strategies for preventing toxicity and promoting antioxidant and anti-inflammatory actions of bilirubin

Bilirubin (BR) is the final product of haem catabolism. Disruptions along BR metabolic/transport pathways resulting from inherited disorders can increase plasma BR concentration (hyperbilirubinaemia). Unconjugated hyperbilirubinemia may induce BR accumulation in brain, potentially causing irreversible neurological damage, a condition known as BR encephalopathy or kernicterus, to which newborns are especially vulnerable. Numerous pharmaceutical strategies, mostly based on hemoperfusion, have been proposed over the last decades to identify new valid, low-risk alternatives for BR removal from plasma. On the other hand, accumulating evidence indicates that BR produces health benefits due to its potent antioxidant, anti-inflammatory and immunomodulatory action with a significant potential for the treatment of a multitude of diseases. The present manuscript reviews both such aspects of BR pharmacology, gathering literature data on applied pharmaceutical strategies adopted to: (i) reduce the plasma BR concentration for preventing neurotoxicity; (ii) produce a therapeutic effect based on BR efficacy in the treatment of many disorders.

Bilirubin Prevents the TH+ Dopaminergic Neuron Loss in a Parkinson's Disease Model by Acting on TNF-α

Parkinson's disease (PD), the fastest-growing movement disorder, is still challenged by the unavailability of disease-modifying therapy. Mildly elevated levels of unconjugated bilirubin (UCB, PubChem CID 5280352) have been shown to be protective against several extra-CNS diseases, and the effect is attributed to its well-known anti-oxidant and anti-inflammatory capability. We explored the neuroprotective effect of low concentrations of UCB (from 0.5 to 4 µM) in our PD model based on organotypic brain cultures of substantia nigra (OBCs-SN) challenged with a low dose of rotenone (Rot). UCB at 0.5 and 1 µM fully protects against the loss of TH+ (dopaminergic) neurons (DOPAn). The alteration in oxidative stress is involved in TH+ positive neuron demise induced by Rot, but is not the key player in UCB-conferred protection. On the contrary, inflammation, specifically tumor necrosis factor alpha (TNF-α), was found to be the key to UCB protection against DOPAn sufferance. Further work will be needed to introduce the use of UCB into clinical settings, but determining that TNF-α plays a key role in PD may be crucial in designing therapeutic options.

Bile pigments in emergency and critical care medicine

Bile pigments, such as bilirubin and biliverdin, are end products of the heme degradation pathway in mammals and are widely known for their cytotoxic effects. However, recent studies have revealed that they exert cytoprotective effects through antioxidative, anti-inflammatory, and immunosuppressive properties. All these mechanisms are indispensable in the treatment of diseases in the field of emergency and critical care medicine, such as coronary ischemia, stroke, encephalomyelitis, acute lung injury/acute respiratory distress syndrome, mesenteric ischemia, and sepsis. While further research is required before the safe application of bile pigments in the clinical setting, their underlying mechanisms shed light on their utilization as therapeutic agents in the field of emergency and critical care medicine. This article aims to summarize the current understanding of bile pigments and re-evaluate their therapeutic potential in the diseases listed above.

Blockade of PGK1 and ALDOA enhances bilirubin control of Th17 cells in Crohn's disease

Unconjugated bilirubin (UCB) confers Th17-cells immunosuppressive features by activating aryl-hydrocarbon-receptor, a modulator of toxin and adaptive immune responses. In Crohn's disease, Th17-cells fail to acquire regulatory properties in response to UCB, remaining at an inflammatory/pathogenic state. Here we show that UCB modulates Th17-cell metabolism by limiting glycolysis and through downregulation of glycolysis-related genes, namely phosphoglycerate-kinase-1 (PGK1) and aldolase-A (ALDOA). Th17-cells of Crohn's disease patients display heightened PGK1 and ALDOA and defective response to UCB. Silencing of PGK1 or ALDOA restores Th17-cell response to UCB, as reflected by increase in immunoregulatory markers like FOXP3, IL-10 and CD39. In vivo, PGK1 and ALDOA silencing enhances UCB salutary effects in trinitro-benzene-sulfonic-acid-induced colitis in NOD/scid/gamma humanized mice where control over disease activity and enhanced immunoregulatory phenotypes are achieved. PGK1 and/or ALDOA blockade might have therapeutic effects in Crohn's disease by favoring acquisition of regulatory properties by Th17-cells along with control over their pathogenic potential.

The different facets of heme-oxygenase 1 in innate and adaptive immunity

Heme oxygenase (HO) enzymes are responsible for the main oxidative step in heme degradation, generating equimolar amounts of free iron, biliverdin and carbon monoxide. HO-1 is induced as a crucial stress response protein, playing protective roles in physiologic and pathological conditions, due to its antioxidant, anti-apoptotic and anti-inflammatory effects. The mechanisms behind HO-1-mediated protection are being explored by different studies, affecting cell fate through multiple ways, such as reduction in intracellular levels of heme and ROS, transcriptional regulation, and through its byproducts generation. In this review we focus on the interplay between HO-1 and immune-related signaling pathways, which culminate in the activation of transcription factors important in immune responses and inflammation. We also discuss the dual interaction of HO-1 and inflammatory mediators that govern resolution and tissue damage. We highlight the dichotomy of HO-1 in innate and adaptive immune cells development and activation in different disease contexts. Finally, we address different known anti-inflammatory pharmaceuticals that are now being described to modulate HO-1, and the possible contribution of HO-1 in their anti-inflammatory effects.

Acute decompensation events differentially impact the risk of nosocomial infections and short-term outcomes in patients with cirrhosis

Aims

This research aimed to evaluate the influence of acute decompensation (AD) events upon admission on the subsequent risk of nosocomial infections (NIs) and the synergy between AD and the following NIs on the short-term outcome.

Methods

A total of 419 hospitalized individuals with cirrhosis and AD participated in the current study. Various AD events at admission and outcomes in patients with or without NIs were compared. The logistic regression and Cox proportional hazards models were designed for NIs development and liver transplant (LT)-free mortality at 28 and 90 days, respectively.

Results

During hospitalization, 91 patients developed NIs. Notably, a higher proportion of patients with NIs had jaundice (52.7 vs. 30.5%; p < 0.001) and bacterial infections (37.4 vs. 20.7%; p = 0.001) at admission compared to patients without NIs, while a lower proportion suffered gastrointestinal hemorrhage (16.5 vs. 36.6%; p < 0.001). Multivariate analysis revealed that jaundice was independently linked with the development of NIs (OR, 2.732; 95% CI: 1.104–6.762). The 28-day (16.5 vs. 7.3%; p = 0.008) and 90-day (27.5 vs. 15.9%; p = 0.011) LT-free mortality rates of patients with NIs were significantly higher than those without NIs. According to the Cox proportional hazards model, jaundice remained an independent risk factor for 90-day death (HR, 5.775; 95% CI: 1.217–27.397). The connection between total bilirubin and 90-day mortality was nonlinear, and a 6 mg/mL threshold was proposed.

Conclusion

The types of AD events differentially predispose to risk of NIs. Presenting jaundice at admission is independently associated with NIs occurrence and increased 90-day mortality of patients with NIs. Antibiotic prophylaxis may benefit this specific subset of patients.

Post Transplantation Bilirubin Nanoparticles Ameliorate Murine Graft Versus Host Disease via a Reduction of Systemic and Local Inflammation

Allogeneic stem cell transplantation is a curative immunotherapy where patients receive myeloablative chemotherapy and/or radiotherapy, followed by donor stem cell transplantation. Graft versus host disease (GVHD) is a major complication caused by dysregulated donor immune system, thus a novel strategy to modulate donor immunity is needed to mitigate GVHD. Tissue damage by conditioning regimen is thought to initiate the inflammatory milieu that recruits various donor immune cells for cross-priming of donor T cells against alloantigen and eventually promote strong Th1 cytokine storm escalating further tissue damage. Bilirubin nanoparticles (BRNP) are water-soluble conjugated of bilirubin and polyethylene glycol (PEG) with potent anti-inflammatory properties through its ability to scavenge reactive oxygen species generated at the site of inflammation. Here, we evaluated whether BRNP treatment post-transplantation can reduce initial inflammation and subsequently prevent GVHD in a major histocompatibility (MHC) mismatched murine GVHD model. After myeloablative irradiation, BALB/c mice received bone marrow and splenocytes isolated from C57BL/6 mice, with or without BRNP (10 mg/kg) daily on days 0 through 4 post-transplantation, and clinical GVHD and survival was monitored for 90 days. First, BRNP treatment significantly improved clinical GVHD score compared to untreated mice (3.4 vs 0.3, p=0.0003), and this translated into better overall survival (HR 0.0638, p=0.0003). Further, BRNPs showed a preferential accumulation in GVHD target organs leading to a reduced systemic and local inflammation evidenced by lower pathologic GVHD severity as well as circulating inflammatory cytokines such as IFN-γ. Lastly, BRNP treatment post-transplantation facilitated the reconstitution of CD4⁺ iNK T cells and reduced expansion of proinflammatory CD8α⁺ iNK T cells and neutrophils especially in GVHD organs. Lastly, BRNP treatment decreased ICOS⁺ or CTLA-4⁺ T cells but not PD-1⁺ T cells suggesting a decreased level of T cell activation but maintaining T cell tolerance. In conclusion, we demonstrated that BRNP treatment post-transplantation ameliorates murine GVHD via diminishing the initial tissue damage and subsequent inflammatory responses from immune subsets.

Anti-Oxidative Therapy in Islet Cell Transplantation

Islet cell transplantation has become a favorable therapeutic approach in the treatment of Type 1 Diabetes due to the lower surgical risks and potential complications compared to conventional pancreas transplantation. Despite significant improvements in islet cell transplantation outcomes, several limitations hamper long-term graft survival due to tremendous damage and loss of islet cells during the islet cell transplantation process. Oxidative stress has been identified as an omnipresent stressor that negatively affects both the viability and function of isolated islets. Furthermore, it has been established that at baseline, pancreatic β cells exhibit reduced antioxidative capacity, rendering them even more susceptible to oxidative stress during metabolic stress. Thus, identifying antioxidants capable of conferring protection against oxidative stressors present throughout the islet transplantation process is a valuable approach to improving the overall outcomes of islet cell transplantation. In this review we discuss the potential application of antioxidative therapy during each step of islet cell transplantation.

Role of Butylphthalide in Immunity and Inflammation: Butylphthalide May Be a Potential Therapy for Anti-Inflammation and Immunoregulation

Inflammation and immunity play an essential role in disease pathogenesis. 3-N-Butylphthalide (NBP), a group of compounds extracted from seeds of Apium graveolens (Chinese celery), has been demonstrated as an efficient and effective therapy for ischemic stroke. The amount of research on NBP protective effect is increasing at pace, such as microcircular reconstruction, alleviating inflammation, ameliorating brain edema and blood-brain barrier (BBB) damage, mitochondrial function protection, antiplatelet aggregation, antithrombosis, decreasing oxidative damage, and reducing neural cell apoptosis. There has been increasing research emphasizing the association between NBP and immunity and inflammation in the past few years. Hence, it is aimed at reviewing the related literature and summarizing the underlying anti-inflammatory and immunoregulatory function of NBP in various disorders.

Clinical Significance of Novel Neutrophil-Based Biomarkers in the Diagnosis and Prediction of Response to Infliximab Therapy in Crohn’s Disease

With the increasing incidence and prevalence, Crohn’s disease (CD) has become one of the most challenging diseases in both diagnosis and treatment of gastroenterology. Evaluation of the disease activity and mucosal healing guides clinical decisions regarding subsequent therapy for CD. In this study, we enrolled a total of 144 patients with CD and 239 healthy controls were enrolled. Clinical characteristics and laboratory parameters of enrolled subjects were retrieved from the electronic medical record database of our hospital. Serum cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA). Mucosa expression levels of inflammatory agents were measured by quantitative RT-PCR (qRT-PCR). We identified two neutrophil-based indexes, the neutrophil-to-albumin ratio (NAR) and neutrophil-to-bilirubin ratio (NBR), both of which had not yet been explored in CD or UC. NAR and NBR were significantly increased in patients with CD compared to those in healthy controls, and both indexes showed significantly positive correlations with CD activity and inflammatory load. In note, NAR and NBR showed better performance than blood neutrophil percentage, serum albumin, or bilirubin alone in these scenarios. More importantly, both NAR and NBR discriminated CD patients who completely or partially responded to infliximab (IFX) induction therapy from those with primary non-response. Our observations suggest that NAR and NBR may serve as promising biomarkers in the diagnosis and prediction of response to IFX therapy in CD.

Clinical Significance of Albumin- and Bilirubin-Based Biomarkers in Glaucoma: A Retrospective Case-Control Study

Glaucoma is the second leading cause of global blindness. The etiology of glaucoma is complicated. In addition to elevated intraocular pressure (IOP), several other mechanisms have been implicated in pathogenesis, such as oxidative stress and systemic inflammation. Serum albumin (ALB) and bilirubin (BIL) have been reported to have potent antioxidant properties and contribute to maintain redox homeostasis in various diseases. However, associations between these parameters and glaucoma remain mostly unknown. Here, we conducted a retrospective case-control study, revealing that serum ALB, total BIL (TBIL), and indirect BIL (IBIL) levels were markedly lower in glaucoma patients than those in healthy controls. Furthermore, the neutrophil-to-ALB (NAR), neutrophil-to-TBIL (NTBR), and neutrophil-to-IBIL (NIBR) ratios were greatly higher in glaucoma. Additionally, interestingly, lower ALB and BIL levels and higher NAR, NTBR, and NIBR were associated with severer glaucomatous visual impairment, and NAR, NTBR, and NIBR showed good accuracy as diagnostic tests for glaucoma severity, suggesting these indices might be useful as discriminative biomarkers for disease severity. Our current findings demonstrate associations between ALB, BIL, NAR, NTBR, NIBL, and glaucoma. It might be useful to use NAR, NTBR, and NIBR as predictive markers for disease severity and employ ALB/BIL as alternative therapy or adjuvant medicines in glaucoma patients.

Prognostic significance of systemic immune-inflammation index and platelet-albumin-bilirubin grade in patients with pancreatic cancer undergoing radical surgery

BACKGROUND

Systemic inflammatory markers are associated with patient survival in pancreatic cancer (PC). The aim of this study was to investigate the prognostic significance of the systemic immune-inflammation index (SII) in PC patients who underwent radical surgery. Platelet-albumin-bilirubin (PALBI) grade is a composite evaluation index based on liver function. Patients with pancreatic head cancer are prone to obstructive jaundice, which leads to abnormal liver function. Based on this, we also explored the prognostic value of PALBI grade in PC patients.

METHODS

Patients with pathologically confirmed PC who had undergone radical surgery (with negative surgical margin) for the first time at the Affiliated Hospital of Qingdao University from January 2013 to December 2019 and followed up by December 2020 were retrospectively analyzed. Peripheral blood cell count is easily affected by infection or hematological diseases, which affects the results, so it is excluded. Clinical data and laboratory examination indexes were collected. The SII and PALBI grade were calculated. The cutoff values were determined using the Youden index. The Cox proportional hazards regression model was used to analyze the prognostic value of the SII and PALBI grade through univariate and multivariate survival analysis.

RESULTS

A total of 214 patients [median age, 60.29 years; 128 (59.8%) men] met the inclusion criteria. There were 140 patients (65.4%) with pancreatic head cancer according to the tumor location. They were divided into high and low SII or PALBI groups by cutoff values of 705 and -5.6, respectively. According to the multivariate analysis, SII (P<0.001) was an independent factor negatively associated with overall survival (OS) and disease-free survival (DFS). In patients with pancreatic head cancer, PALBI grade was associated with shorter OS (P=0.031). The combination of high SII and high PALBI grade had stronger predictive value for poor prognosis (log-rank test, P<0.001), which the OS was 11.3 months less than the combination of low two groups.

CONCLUSIONS

SII was a promising prognostic biomarker in PC. And PALBI grade also showed predictive value for patients with pancreatic head cancer. Therefore, it can help predict the treatment outcomes in these patients.

Immune Regulation of Heme Oxygenase-1 in Allergic Airway Inflammation

Heme oxygenase-1 (HO-1) is not only a rate-limiting enzyme in heme metabolism but is also regarded as a protective protein with an immunoregulation role in asthmatic airway inflammation. HO-1 exerts an anti-inflammation role in different stages of airway inflammation via regulating various immune cells, such as dendritic cells, mast cells, basophils, T cells, and macrophages. In addition, the immunoregulation role of HO-1 may differ according to subcellular locations.

Bilirubin represents a negative regulator of ILC2 in allergic airway inflammation

Group 2 innate lymphoid cells (ILC2s) play an important role in allergic airway inflammation. Despite recent advances in defining molecular mechanisms that control ILC2 development and function, the role of endogenous metabolites in the regulation of ILC2s remains poorly understood. Herein, we demonstrated that bilirubin, an end product of heme catabolism, was a potent negative regulator of ILC2s. Bilirubin metabolism was found to be significantly induced during airway inflammation in mouse models. The administration of unconjugated bilirubin (UCB) dramatically suppressed ILC2 responses to interleukin (IL)-33 in mice, including cell proliferation and the production of effector cytokines. Furthermore, UCB significantly alleviated ILC2-driven airway inflammation, which was aggravated upon clearance of endogenous UCB. Mechanistic studies showed that the effects of bilirubin on ILC2s were associated with downregulation of ERK phosphorylation and GATA3 expression. Clinically, newborns with hyperbilirubinemia displayed significantly lower levels of ILC2 with impaired function and suppressed ERK signaling. Together, these findings indicate that bilirubin serves as an endogenous suppressor of ILC2s and might have potential therapeutic value in the treatment of allergic airway inflammation.

NRF2: KEAPing Tumors Protected

The Kelch-like ECH-associated protein 1 (KEAP1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway plays a physiologic protective role against xenobiotics and reactive oxygen species. However, activation of NRF2 provides a powerful selective advantage for tumors by rewiring metabolism to enhance proliferation, suppress various forms of stress, and promote immune evasion. Genetic, epigenetic, and posttranslational alterations that activate the KEAP1/NRF2 pathway are found in multiple solid tumors. Emerging clinical data highlight that alterations in this pathway result in resistance to multiple therapies. Here, we provide an overview of how dysregulation of the KEAP1/NRF2 pathway in cancer contributes to several hallmarks of cancer that promote tumorigenesis and lead to treatment resistance. SIGNIFICANCE: Alterations in the KEAP1/NRF2 pathway are found in multiple cancer types. Activation of NRF2 leads to metabolic rewiring of tumors that promote tumor initiation and progression. Here we present the known alterations that lead to NRF2 activation in cancer, the mechanisms in which NRF2 activation promotes tumors, and the therapeutic implications of NRF2 activation.

MGE-Like Neural Progenitor Cell Survival and Expression of Parvalbumin and Proenkephalin in a Jaundiced Rat Model of Kernicterus

Kernicterus is a permanent condition caused by brain damage from bilirubin toxicity. Dystonia is one of the most debilitating symptoms of kernicterus and results from damage to the globus pallidus (GP). One potential therapeutic strategy to treat dystonia in kernicterus is to replace lost GP neurons and restore basal ganglia circuits through stem cell transplantation. Toward this end, we differentiated human embryonic stem cells (hESCs) into medial ganglion eminence (MGE; the embryological origin of most of the GP neurons)-like neural precursor cells (NPCs). We determined neurochemical phenotype in cell culture and after transplanting into the GP of jaundiced Gunn rats. We also determined grafted cell survival as well as migration, distribution, and morphology after transplantation. As in the GP, most cultured MGE-like NPCs expressed γ-aminobutyric acid (GABA), with some co-expressing markers for parvalbumin (PV) and others expressing markers for pro-enkephalin (PENK). MGE-like NPCs survived in brains at least 7 weeks after transplantation, with most aggregating near the injection site. Grafted cells expressed GABA and PV or PENK as in the normal GP. Although survival was low and the maturity of grafted cells varied, many cells produced neurite outgrowth. While promising, our results suggest the need to further optimize the differentiation protocol for MGE-like NPC for potential use in treating dystonia in kernicterus.

Assessment of the albumin-bilirubin grade as a prognostic factor in patients with non-small-cell lung cancer receiving anti-PD-1-based therapy

Introduction

The albumin-bilirubin (ALBI) grade is a novel indicator of the liver function. Some studies showed that the ALBI grade was a prognostic and predictive biomarker for the efficacy of chemotherapy in cancer patients. The association between the ALBI grade and outcomes in patients with non-small-cell lung cancer (NSCLC) treated with cancer immunotherapy, however, is poorly understood.

Methods

We retrospectively enrolled 452 patients with advanced or recurrent NSCLC who received anti-programmed cell death protein 1 (PD-1)-based therapy between 2016 and 2019 at three medical centers in Japan. The ALBI score was calculated from albumin and bilirubin measured at the time of treatment initiation and was stratified into three categories, ALBI grade 1-3, with reference to previous reports. We examined the clinical impact of the ALBI grade on the outcomes of NSCLC patients receiving anti-PD-1-based therapy using Kaplan–Meier survival curve analysis with log-rank test and Cox proportional hazards regression analysis.

Results

The classifications of the 452 patients were as follows: grade 1, n = 158 (35.0%); grade 2, n = 271 (60.0%); and grade 3, n = 23 (5.0%). Kaplan–Meier survival curve analysis showed that the ALBI grade was significantly associated with progression-free survival and overall survival. Moreover, Cox regression analysis revealed that the ALBI grade was an independent prognostic factor for progression-free survival and overall survival.

Conclusion

The ALBI grade was an independent prognostic factor for survival in patients with advanced or recurrent NSCLC who receive anti-PD-1-based therapy. These findings should be validated in a prospective study with a larger sample size.

•

ALBI grade is calculated from albumin and bilirubin.

•

We evaluated the impact of ALBI grade on survival in NSCLC patients receiving immune checkpoint inhibitors.

•

ALBI grade was an independent prognostic factor for progression-free survival (PFS) and overall survival (OS).

•

ALBI grade effectively stratified PFS and OS in patients with performance status 1-3.

•

ALBI grade was significantly associated with PFS and OS, regardless of programmed death ligand-1.

Reversing an Oncogenic Epithelial-to-Mesenchymal Transition Program in Breast Cancer Reveals Actionable Immune Suppressive Pathways

Approval of checkpoint inhibitors for treatment of metastatic triple negative breast cancer (mTNBC) has opened the door for the use of immunotherapies against this disease. However, not all patients with mTNBC respond to current immunotherapy approaches such as checkpoint inhibitors. Recent evidence demonstrates that TNBC metastases are more immune suppressed than primary tumors, suggesting that combination or additional immunotherapy strategies may be required to activate an anti-tumor immune attack at metastatic sites. To identify other immune suppressive mechanisms utilized by mTNBC, our group and others manipulated oncogenic epithelial-to-mesenchymal transition (EMT) programs in TNBC models to reveal differences between this breast cancer subtype and its more epithelial counterpart. This review will discuss how EMT modulation revealed several mechanisms, including tumor cell metabolism, cytokine milieu and secretion of additional immune modulators, by which mTNBC cells may suppress both the innate and adaptive anti-tumor immune responses. Many of these pathways/proteins are under preclinical or clinical investigation as therapeutic targets in mTNBC and other advanced cancers to enhance their response to chemotherapy and/or checkpoint inhibitors.

Metabolomic Profiles of Men and Women Ischemic Stroke Patients

Background: Stroke is known to affect both men and women; however, incidence and outcomes differ between them. Therefore, the discovery of novel, sex-specific, blood-based biomarkers for acute ischemic stroke (AIS) patients has the potential to enhance the understanding of the etiology of this deadly disease in the content of sex. The objective of this study was to identify serum metabolites associated with male and female AIS patients. Methods: Metabolites were measured with the use of untargeted, reverse-phase ultra-performance liquid chromatography-tandem mass spectrometry quantification from blood specimens collected from AIS patients. Samples were collected from 36 patients comprising each of 18 men and women with matched controls. Metabolic pathway analysis and principal component analysis (PCA) was used to differentiate metabolite profiles for male and female AIS patients from the control, while logistic regression was used to determine differences in metabolites between male and female AIS patients. Results: In female AIS patients, 14 distinct altered metabolic pathways and 49 corresponding metabolites were identified, while 39 metabolites and 5 metabolic pathways were identified in male patients. Metabolites that are predictive of ischemic stroke in female patients were 1-(1-enyl-palmitoyl)-2-arachidonoyl-GPC (P-16:0/20:4) (AUC = 0.914, 0.765–1.000), 1-(1-enyl-palmitoyl)-2-palmitoyl-GPC (P-16:0/16:0) (AUC = 0.840, 0.656–1.000), and 5,6-dihydrouracil (P-16:0/20:2) (AUC = 0.815, 0.601–1.000). Significant metabolites that were predictive of stroke in male patients were 5alpha-androstan-3alpha,17beta-diol disulfate (AUC = 0.951, 0.857–1.000), alpha-hydroxyisocaproate (AUC = 0.938, 0.832–1.000), threonate (AUC = 0.877, 0.716–1.000), and bilirubin (AUC = 0.817, 0.746–1.000). Conclusions: In the current study, the untargeted serum metabolomics platform identified multiple pathways and metabolites associated with male and female AIS patients. Further research is necessary to characterize how these metabolites are associated with the pathophysiology in male and female AIS patients.

Immunomodulatory Effects of Heme Oxygenase-1 in Kidney Disease

Kidney disease is a general term for heterogeneous damage that affects the function and the structure of the kidneys. The rising incidence of kidney diseases represents a considerable burden on the healthcare system, so the development of new drugs and the identification of novel therapeutic targets are urgently needed. The pathophysiology of kidney diseases is complex and involves multiple processes, including inflammation, autophagy, cell-cycle progression, and oxidative stress. Heme oxygenase-1 (HO-1), an enzyme involved in the process of heme degradation, has attracted widespread attention in recent years due to its cytoprotective properties. As an enzyme with known anti-oxidative functions, HO-1 plays an indispensable role in the regulation of oxidative stress and is involved in the pathogenesis of several kidney diseases. Moreover, current studies have revealed that HO-1 can affect cell proliferation, cell maturation, and other metabolic processes, thereby altering the function of immune cells. Many strategies, such as the administration of HO-1-overexpressing macrophages, use of phytochemicals, and carbon monoxide-based therapies, have been developed to target HO-1 in a variety of nephropathological animal models, indicating that HO-1 is a promising protein for the treatment of kidney diseases. Here, we briefly review the effects of HO-1 induction on specific immune cell populations with the aim of exploring the potential therapeutic roles of HO-1 and designing HO-1-based therapeutic strategies for the treatment of kidney diseases.