Impaired Bile Secretion Promotes Hepatobiliary Injury in Sickle Cell Disease

Hepatobiliary complications in patients with sickle cell disease: A 30-year review of 1009 patients

BACKGROUND

Sickle cell disease (SCD) is the most common hemoglobinopathy. We aimed to identify the prevalence of hepatobiliary injury and its association with mortality in SCD.

METHODS

Patients with SCD followed at a dedicated clinic at our tertiary center were retrospectively evaluated with descriptive statistics. Correlations between hepatobiliary complications and SCD complications were expressed as ORs. To evaluate mortality predictors, log-rank testing was used for univariate analysis and Cox proportional hazards for multivariable analysis, with time-dependent covariates for biochemistry.

RESULTS

Between January 1990 and December 2020, 1009 patients with SCD were identified; 63.2% were HbSS. The median age at first clinic visit was 26.4 years (IQR: 18.9-37.1), 44.3% were male, and 62.6% were ever treated with hydroxyurea. The median follow-up was 4.8 years (IQR: 1.9-8.5); mortality was 8.9%. The most frequent hepatobiliary manifestations were cholelithiasis (n=431 [42.7%]) and iron overload (n=121; 12%). Chronic viral hepatitis was reported in only 18 patients. Twenty-nine patients (2.1%) had peak ALT> 2× upper limit of normal, 15 (2.3%) had peak ALP> 2× upper limit of normal, 97 (10.3%) had peak total bilirubin >103 μmol/L, (6.02 mg/dL), and 184 (18.2%) patients had elevated peak direct bilirubin. Hepatomegaly was reported in 37 patients (3.7%), while 24 patients (2.4%) were clinically cirrhotic. Five patients received a liver transplant. In an exploratory multivariate model, age (HR 1.08 [95% CI: 1.05-1.11]), ALT elevation (HR 1.52 [95% CI: 1.29-1.78]), and total bilirubin >103 μmol/L (HR 9.3 [95% CI: 3.95-21.9]) predicted mortality independently.

CONCLUSIONS

Hepatobiliary complications are common in patients with SCD and require vigilance for identification.

GBT1118, a Voxelotor Analog, Ameliorates Hepatopathy in Sickle Cell Disease

Background and Objectives: In sickle cell disease (SCD), hepatopathy is a cumulative consequence of ischemia/reperfusion (I/R) injury from a vaso-occlusive crisis, tissue inflammation, and iron overload due to blood transfusion. Hepatopathy is a major contributing factor of shortened life span in SCD patients. We hypothesized that the voxelotor, a hemoglobin allosteric modifier, ameliorates sickle hepatopathy. Materials and Methods: Townes SCD mice and their controls were treated with either chow containing GBT1118, a voxelotor analog, or normal chow. We evaluated inflammation, fibrosis, apoptosis and ferroptosis in their livers using qPCR, ELISA, histology, and immunohistochemistry. Results: GBT1118 treatment resulted in reduced hemolysis, iron overload and inflammation in the liver of SCD mice. There were significant reductions in the liver enzyme levels and bile acids. Furthermore, GBT1118-treated mice exhibited reduced apoptosis, necrosis, and fibrosis. Increased ferroptosis as evident from elevated 4-hydroxynonenal (4-HNE) staining, malondialdehyde (MDA) levels, and expression of Ptgs2 and Slc7a11 mRNAs, were also significantly reduced after GBT1118 treatment. To explain the increased ferroptosis, we evaluated iron homeostasis markers in livers. SCD mice showed decreased expression of heme oxygenase-1, ferritin, hepcidin, and ferroportin mRNA levels. GBT1118 treatment significantly increased expressions of these genes. Conclusions: Our results suggest GBT1118 treatment in SCD confers the amelioration of sickle hepatopathy by reducing inflammation, fibrosis, apoptosis, iron overload and ferroptosis.

Hemoglobin scavenger receptor CD163 as a potential biomarker of hemolysis-induced hepatobiliary injury in sickle cell disease

Sickle cell disease (SCD)-associated chronic hemolysis promotes oxidative stress, inflammation, and thrombosis leading to organ damage, including liver damage. Hemoglobin scavenger receptor CD163 plays a protective role in SCD by scavenging both hemoglobin-haptoglobin complexes and cell-free hemoglobin. A limited number of studies in the past have shown a positive correlation of CD163 expression with poor disease outcomes in patients with SCD. However, the role and regulation of CD163 in SCD-related hepatobiliary injury have not been fully elucidated yet. Here we show that chronic liver injury in SCD patients is associated with elevated levels of hepatic membrane-bound CD163. Hemolysis and increase in hepatic heme, hemoglobin, and iron levels elevate CD163 expression in the SCD mouse liver. Mechanistically we show that heme oxygenase-1 (HO-1) positively regulates membrane-bound CD163 expression independent of nuclear factor erythroid 2-related factor 2 (NRF2) signaling in SCD liver. We further demonstrate that the interaction between CD163 and HO-1 is not dependent on CD163-hemoglobin binding. These findings indicate that CD163 is a potential biomarker of SCD-associated hepatobiliary injury. Understanding the role of HO-1 in membrane-bound CD163 regulation may help identify novel therapeutic targets for hemolysis-induced chronic liver injury.

Impaired hemoglobin clearance by sinusoidal endothelium promotes vaso-occlusion and liver injury in sickle cell disease

Sickle cell disease (SCD) is a monogenic disorder that affects 100,000 African-Americans and millions of people worldwide. Intra-erythrocytic polymerization of sickle hemoglobin (HbS) promotes erythrocyte sickling, impaired rheology, ischemia and hemolysis, leading to the development of progressive liver injury in SCD. Liver-resident macrophages and monocytes are known to enable the clearance of HbS; however, the role of liver sinusoidal endothelial cells (LSEC) in HbS clearance and liver injury in SCD remains unknown. Using real-time intravital (in vivo) imaging in mice liver as well as flow cytometric analysis and confocal imaging of primary human LSEC, we show for the first time that liver injury in SCD is associated with accumulation of HbS and iron in the LSEC, leading to senescence of these cells. Hemoglobin uptake by LSEC was mediated by micropinocytosis. Hepatic monocytes were observed to attenuate LSEC senescence by accelerating HbS clearance in the liver of SCD mice; however, this protection was impaired in P-selectin-deficient SCD mice secondary to reduced monocyte recruitment in the liver. These findings are the first to suggest that LSEC contribute to HbS clearance and HbS-induced LSEC senescence promotes progressive liver injury in SCD mice. Our results provide a novel insight into the pathogenesis of hemolysis-induced chronic liver injury in SCD caused by LSEC senescence. Identifying the regulators of LSEC-mediated HbS clearance may lead to new therapies to prevent the progression of liver injury in SCD.

Acute sickle cell hepatopathy: A case report and literature review

Sickle cell disease (SCD) is an inherited hemoglobinopathy with protean clinical manifestations. The liver could be affected by various SCD-associated complications of an overlapping nature. The clinical presentations of "sickle cell hepatopathy" range from clinically asymptomatic patients to those with life-threatening complications. Herein we report an SCD patient who presented with right upper quadrant abdominal pain and jaundice, eventually diagnosed as a self-limited form of acute sickle cell hepatopathy with overlapping features of acute hepatic crisis and benign intrahepatic cholestasis. Using this patient as an illustration, we will review the spectrum of hepatobiliary presentations in the SCD population.

Mouse models of sickle cell disease: Imperfect and yet very informative

The root cause of sickle cell disease (SCD) has been known for nearly a century, however, few therapies to treat the disease are available. Over several decades of work, with advances in gene editing technology and after several iterations of mice with differing genotype/phenotype relationships, researchers have developed humanized SCD mouse models. However, while a large body of preclinical studies has led to huge gains in basic science knowledge about SCD in mice, this knowledge has not led to the development of effective therapies to treat SCD-related complications in humans, thus leading to frustration with the paucity of translational progress in the SCD field. The use of mouse models to study human diseases is based on the genetic and phenotypic similarities between mouse and humans (face validity). The Berkeley and Townes SCD mice express only human globin chains and no mouse hemoglobin. With this genetic composition, these models present many phenotypic similarities, but also significant discrepancies that should be considered when interpreting preclinical studies results. Reviewing genetic and phenotypic similarities and discrepancies and examining studies that have translated to humans and those that have not, offer a better perspective of construct, face, and predictive validities of humanized SCD mouse models.

The liver in sickle cell disease

Liver involvement in SCD patients is frequent but often misdiagnosed or underestimated, except in case of advanced liver diseases. Because of so far poorly recognized forms of chronic SCD-related vascular injury that can silently evolved towards end stages or facilitate ACLF, any persisting liver function tests abnormalities should be carefully investigated, following the above proposed algorithm. Work up and management must be considered multidisciplinary in relationship with a Hepatologist. Early SCD hepatopathy should prompt revision of SCD management to prevent further liver injury and decompensation, discussing transfusion exchanges and hydro urea when not yet initiated, and control for any cofactor of liver injury. The role of HSCT in early SCD hepatopathies also deserves evaluation. In advanced SCD hepatopathies, liver transplantation, which has been rarely performed so far, is the only therapeutic option associated with improved survival. It should definitely be discussed- either electively in case of decompensation in SCD cirrhosis or jaundice/recurrent cholangitis in cholestatic diseases, with excellent outcome, - or emergently in case of ALF or ACLF with more mitigate results. To improve knowledge and management of SCD liver diseases, creation of national and international registries, as well as longitudinal observational cohorts are encouraged.

Long-Term L-Glutamine Treatment Reduces Hemolysis without Ameliorating Hepatic Vaso-Occlusion and Liver Fibrosis in a Mouse Model of Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive monogenic disorder caused by a homozygous mutation in the β-globin gene, which leads to erythrocyte sickling, hemolysis, vaso-occlusion, and sterile inflammation. The administration of oral L-glutamine has been shown to reduce the frequency of pain in SCD patients; however, the long-term effect of L-glutamine in SCD remains to be determined. To understand the long-term effect of L-glutamine administration in the liver we used quantitative liver intravital microscopy and biochemical analysis in humanized SCD mice. We here show that chronic L-glutamine administration reduces hepatic hemoglobin-heme-iron levels but fails to ameliorate ischemic liver injury. Remarkably, we found that this failure in the resolution of hepatobiliary injury and persistent liver fibrosis is associated with the reduced expression of hepatic Kupffer cells post-L-glutamine treatment. These findings establish the importance of investigating the long-term effects of L-glutamine therapy on liver pathophysiology in SCD patients.

Urine metabolomics and microbiome analyses reveal the mechanism of anti-tuberculosis drug-induced liver injury, as assessed for causality using the updated RUCAM: A prospective study

Background

Anti-tuberculosis drug-induced liver injury (ATB-DILI) is one of the most common adverse reactions that brings great difficulties to the treatment of tuberculosis. Thus, early identification of individuals at risk for ATB-DILI is urgent. We conducted a prospective cohort study to analyze the urinary metabolic and microbial profiles of patients with ATB-DILI before drug administration. And machine learning method was used to perform prediction model for ATB-DILI based on metabolomics, microbiome and clinical data.

Methods

A total of 74 new TB patients treated with standard first-line anti-TB treatment regimens were enrolled from West China Hospital of Sichuan University. Only patients with an updated RUCAM score of 6 or more were accepted in this study. Nontargeted metabolomics and microbiome analyses were performed on urine samples prior to anti-tuberculosis drug ingestion to screen the differential metabolites and microbes between the ATB-DILI group and the non-ATB-DILI group. Integrating electronic medical records, metabolomics, and microbiome data, four machine learning methods was used, including random forest algorithm, artificial neural network, support vector machine with the linear kernel and radial basis function kernel.

Results

Of all included patients, 69 patients completed follow-up, with 16 (23.19%) patients developing ATB-DILI after antituberculosis treatment. Finally, 14 ATB-DILI patients and 30 age- and sex-matched non-ATB-DILI patients were subjected to urinary metabolomic and microbiome analysis. A total of 28 major differential metabolites were screened out, involving bile secretion, nicotinate and nicotinamide metabolism, tryptophan metabolism, ABC transporters, etc. Negativicoccus and Actinotignum were upregulated in the ATB-DILI group. Multivariate analysis also showed significant metabolic and microbial differences between the non-ATB-DILI and severe ATB-DILI groups. Finally, the four models showed high accuracy in predicting ATB-DILI, with the area under the curve of more than 0.85 for the training set and 1 for the validation set.

Conclusion

This study characterized the metabolic and microbial profile of ATB-DILI risk individuals before drug ingestion for the first time. Metabolomic and microbiome characteristics in patient urine before anti-tuberculosis drug ingestion may predict the risk of liver injury after ingesting anti-tuberculosis drugs. Machine learning algorithms provides a new way to predict the occurrence of ATB-DILI among tuberculosis patients.

Liver-to-lung microembolic NETs promote gasdermin D-dependent inflammatory lung injury in sickle cell disease

Acute lung injury, referred to as the acute chest syndrome, is a major cause of morbidity and mortality in patients with sickle cell disease (SCD), which often occurs in the setting of a vaso-occlusive painful crisis. P-selectin antibody therapy reduces hospitalization of patients with SCD by ∼50%, suggesting that an unknown P-selectin-independent mechanism promotes remaining vaso-occlusive events. In patients with SCD, intraerythrocytic polymerization of mutant hemoglobin promotes ischemia-reperfusion injury and hemolysis, which leads to the development of sterile inflammation. Using intravital microscopy in transgenic, humanized mice with SCD and in vitro studies with blood from patients with SCD, we reveal for the first time that the sterile inflammatory milieu in SCD promotes caspase-4/11-dependent activation of neutrophil-gasdermin D (GSDMD), which triggers P-selectin-independent shedding of neutrophil extracellular traps (NETs) in the liver. Remarkably, these NETs travel intravascularly from liver to lung, where they promote neutrophil-platelet aggregation and the development of acute lung injury. This study introduces a novel paradigm that liver-to-lung embolic translocation of NETs promotes pulmonary vascular vaso-occlusion and identifies a new GSDMD-mediated, P-selectin-independent mechanism of lung injury in SCD.

Molecular Mechanisms of Hepatic Dysfunction in Sickle Cell Disease: Lessons From The Townes Mouse Model

Sickle cell disease (SCD) is an autosomal-recessive-genetic disorder that affects ~100,000 Americans and millions of people worldwide. Erythrocyte sickling, vaso-occlusion, sterile inflammation and hemolysis are the major pathophysiological pathways leading to liver injury in SCD. Although hepatic dysfunction affects up to 10-40% of SCD patients, therapeutic approaches to prevent liver injury in SCD are not known, and the molecular mechanisms promoting progressive liver injury in SCD remain poorly understood. Animal models have been beneficial in bridging the gap between preclinical and translational research in SCD. Recent advances in methodology have allowed the development of several humanized mouse models to address various aspects of SCD related liver diseases. This review provides an overview of current knowledge of the molecular mechanisms and potential therapeutic options of SCD associated liver dysfunction using the Townes mouse model.

Intravital imaging reveals inflammation as a dominant pathophysiology of age-related hepatovascular changes

Aging is the most significant risk factor for the majority of chronic diseases, including liver disease. The cellular, molecular, and pathophysiological mechanisms that promote age-induced hepatovascular changes are unknown due to our inability to visualize changes in liver pathophysiology in live mice over time. We performed quantitative liver intravital microscopy (qLIM) in live C57BL/6J mice to investigate the impact of aging on the hepatovascular system over a 24-mo period. qLIM revealed that age-related hepatic alterations include reduced liver sinusoidal blood flow, increased sinusoidal vessel diameter, and loss of small hepatic vessels. The ductular cell structure deteriorates with age, along with altered expression of hepatic junctional proteins. Furthermore, qLIM imaging revealed increased inflammation in the aged liver, which was linked to increased expression of proinflammatory macrophages, hepatic neutrophils, liver sinusoidal endothelial cells, senescent cells, and procoagulants. Finally, we detected elevated NF-κB pathway activity in aged livers. Overall, these findings emphasize the importance of inflammation in age-related hepatic vasculo-epithelial alterations and highlight the utility of qLIM in studying age-related effects in organ pathophysiology.

Intravital Imaging of Hepatic Blood Biliary Barrier in Live Mice

Understanding the kinetics and spatiotemporal interactions of living cells within the tissue environment requires real-time imaging. The introduction of two-photon microscopy has substantially boosted the power of live intravital imaging, making it possible to obtain information of individual cells in near-physiologic conditions within intact tissues nondestructively. Intravital imaging of the liver has proved useful in understanding its 3D structure, function, and dynamic cellular interactions. Recently we have shown that integrity of the blood-bile barrier in different physiologic and pathophysiologic conditions can be imaged in real time using intravital microscopy. Here we discuss the real-time intravital imaging method to visualize blood-bile barrier integrity in the murine liver. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Live imaging in the mouse liver Support Protocol: Monitoring vital signs of the mouse during live liver imaging Basic Protocol 2: Visualizing blood and bile transport using intravital microscopy.

P-selectin deficiency promotes liver senescence in sickle cell disease mice

Sickle cell disease (SCD) is caused by a homozygous mutation in the β-globin gene, which leads to erythrocyte sickling, vasoocclusion, and intense hemolysis. P-selectin inhibition has been shown to prevent vasoocclusive events in patients with SCD; however, the chronic effect of P-selectin inhibition in SCD remains to be determined. Here, we used quantitative liver intravital microscopy in our recently generated P-selectin-deficient SCD mice to show that chronic P-selectin deficiency attenuates liver ischemia but fails to prevent hepatobiliary injury. Remarkably, we find that this failure in resolution of hepatobiliary injury in P-selectin-deficient SCD mice is associated with the increase in cellular senescence and reduced epithelial cell proliferation in the liver. These findings highlight the importance of investigating the long-term effects of chronic P-selectin inhibition therapy on liver pathophysiology in patients with SCD.

The Liver in Sickle Cell Disease

Liver involvement is found in nearly 40% of children with sickle cell disease. The most frequent complication is cholelithiasis. The most severe complication is acute hepatic crisis, with symptoms ranging from increasing jaundice to multiple organ failure and death. The emergency and mostly efficient treatment is exchange transfusion. Chronic cholangiopathy is increasingly recognized, with autoimmune features in most cases, worsened by chronic ischemia. Transfusion-related iron overload is not yet a concern in children, and hepatotoxicity of iron chelators is rare. We propose recommendations to prevent, explore, and treat these complications. We emphasize the close collaboration required between hepatologists and specialists of sickle cell disease.