Epcam regulates intrahepatic bile duct reconstruction in zebrafish, providing a potential model for primary cholangitis model

Epithelial cell adhesion molecules (EpCAMs) have been identified as surface markers of proliferating ductal cells, which are referred to as liver progenitor cells (LPCs), during liver regeneration and correspond to malignancies. These cells can differentiate into hepatocytes and biliary epithelial cells (BECs) in vitro. EpCAM-positive LPCs are involved in liver regeneration following severe liver injury; however, the in vivo function of EpCAMs in the regenerating liver remains unclear. In the present study, we used a zebrafish model of LPC-driven liver regeneration to elucidate the function of EpCAMs in the regenerating liver in vivo. Proliferating ductal cells were observed after severe hepatocyte loss in the zebrafish model. Analyses of the liver size as well as hepatocyte and BEC markers revealed successful conversion of LPCs to hepatocytes and BECs in epcam mutants. Notably, epcam mutants exhibited severe defects in intrahepatic duct maturation and bile acid secretion in regenerating hepatocytes, suggesting that epcam plays a critical role in intrahepatic duct reconstruction during LPC-driven liver regeneration. Our findings provide insights into human diseases involving non-parenchymal cells, such as primary biliary cholangitis, by highlighting the regulatory effect of epcam on intrahepatic duct reconstruction.

VEGFA mRNA-LNP promotes biliary epithelial cell-to-hepatocyte conversion in acute and chronic liver diseases and reverses steatosis and fibrosis

The liver is known for its remarkable regenerative ability through proliferation of hepatocytes. Yet, during chronic injury or severe hepatocyte death, proliferation of hepatocytes is exhausted. To overcome this hurdle, we propose vascular-endothelial-growth-factor A (VEGFA) as a therapeutic means to accelerate biliary epithelial-cell (BEC)-to-hepatocyte conversion. Investigation in zebrafish establishes that blocking VEGF receptors abrogates BEC-driven liver repair, while VEGFA overexpression promotes it. Delivery of VEGFA via nonintegrative and safe nucleoside-modified mRNA encapsulated into lipid nanoparticles (mRNA-LNPs) in acutely or chronically injured mouse livers induces robust BEC-to-hepatocyte conversion and elimination of steatosis and fibrosis. In human and murine diseased livers, we further identified VEGFA-receptor KDR-expressing BECs associated with KDR-expressing cell-derived hepatocytes. This work defines KDR-expressing cells, most likely being BECs, as facultative progenitors. This study reveals unexpected therapeutic benefits of VEGFA delivered via nucleoside-modified mRNA-LNP, whose safety is widely validated with COVID-19 vaccines, for harnessing BEC-driven repair to potentially treat liver diseases.

Biliary atresia is associated with polygenic susceptibility in ciliogenesis and planar polarity effector genes

BACKGROUND & AIMS

Biliary atresia (BA) is poorly understood and leads to liver transplantation (LT), with the requirement for and associated risks of lifelong immunosuppression, in most children. We performed a genome-wide association study (GWAS) to determine the genetic basis of BA.

METHODS

We performed a GWAS in 811 European BA cases treated with LT in US, Canadian and UK centers, and 4,654 genetically matched controls. Whole-genome sequencing of 100 cases evaluated synthetic association with rare variants. Functional studies included whole liver transcriptome analysis of 64 BA cases and perturbations in experimental models.

RESULTS

A GWAS of common single nucleotide polymorphisms (SNPs), i.e. allele frequencies >1%, identified intronic SNPs rs6446628 in AFAP1 with genome-wide significance (p = 3.93E-8) and rs34599046 in TUSC3 at sub-threshold genome-wide significance (p = 1.34E-7), both supported by credible peaks of neighboring SNPs. Like other previously reported BA-associated genes, AFAP1 and TUSC3 are ciliogenesis and planar polarity effectors (CPLANE). In gene-set-based GWAS, BA was associated with 6,005 SNPs in 102 CPLANE genes (p = 5.84E-15). Compared with non-CPLANE genes, more CPLANE genes harbored rare variants (allele frequency <1%) that were assigned Human Phenotype Ontology terms related to hepatobiliary anomalies by predictive algorithms, 87% vs. 40%, p <0.0001. Rare variants were present in multiple genes distinct from those with BA-associated common variants in most BA cases. AFAP1 and TUSC3 knockdown blocked ciliogenesis in mouse tracheal cells. Inhibition of ciliogenesis caused biliary dysgenesis in zebrafish. AFAP1 and TUSC3 were expressed in fetal liver organoids, as well as fetal and BA livers, but not in normal or disease-control livers. Integrative analysis of BA-associated variants and liver transcripts revealed abnormal vasculogenesis and epithelial tube formation, explaining portal vein anomalies that co-exist with BA.

CONCLUSIONS

BA is associated with polygenic susceptibility in CPLANE genes. Rare variants contribute to polygenic risk in vulnerable pathways via unique genes.

IMPACT AND IMPLICATIONS

Liver transplantation is needed to cure most children born with biliary atresia, a poorly understood rare disease. Transplant immunosuppression increases the likelihood of life-threatening infections and cancers. To improve care by preventing this disease and its progression to transplantation, we examined its genetic basis. We find that this disease is associated with both common and rare mutations in highly specialized genes which maintain normal communication and movement of cells, and their organization into bile ducts and blood vessels during early development of the human embryo. Because defects in these genes also cause other birth defects, our findings could lead to preventive strategies to lower the incidence of biliary atresia and potentially other birth defects.

PPARα activation promotes liver progenitor cell-mediated liver regeneration by suppressing YAP signaling in zebrafish

Despite the robust regenerative capacity of the liver, prolonged and severe liver damage impairs liver regeneration, leading to liver failure. Since the liver co-opts the differentiation of liver progenitor cells (LPCs) into hepatocytes to restore functional hepatocytes, augmenting LPC-mediated liver regeneration may be beneficial to patients with chronic liver diseases. However, the molecular mechanisms underlying LPC-to-hepatocyte differentiation have remained largely unknown. Using the zebrafish model of LPC-mediated liver regeneration, Tg(fabp10a:pt-β-catenin), we present that peroxisome proliferator-activated receptor-alpha (PPARα) activation augments LPC-to-hepatocyte differentiation. We found that treating Tg(fabp10a:pt-β-catenin) larvae with GW7647, a potent PPARα agonist, enhanced the expression of hepatocyte markers and simultaneously reduced the expression of biliary epithelial cell (BEC)/LPC markers in the regenerating livers, indicating enhanced LPC-to-hepatocyte differentiation. Mechanistically, PPARα activation augments the differentiation by suppressing YAP signaling. The differentiation phenotypes resulting from GW7647 treatment were rescued by expressing a constitutively active form of Yap1. Moreover, we found that suppression of YAP signaling was sufficient to promote LPC-to-hepatocyte differentiation. Treating Tg(fabp10a:pt-β-catenin) larvae with the TEAD inhibitor K-975, which suppresses YAP signaling, phenocopied the effect of GW7647 on LPC differentiation. Altogether, our findings provide insights into augmenting LPC-mediated liver regeneration as a regenerative therapy for chronic liver diseases.

Soli-enabled noncontact heart rate detection for sleep and meditation tracking

Heart rate (HR) is a crucial physiological signal that can be used to monitor health and fitness. Traditional methods for measuring HR require wearable devices, which can be inconvenient or uncomfortable, especially during sleep and meditation. Noncontact HR detection methods employing microwave radar can be a promising alternative. However, the existing approaches in the literature usually use high-gain antennas and require the sensor to face the user's chest or back, making them difficult to integrate into a portable device and unsuitable for sleep and meditation tracking applications. This study presents a novel approach for noncontact HR detection using a miniaturized Soli radar chip embedded in a portable device (Google Nest Hub). The chip has a [Formula: see text] dimension and can be easily integrated into various devices. The proposed approach utilizes advanced signal processing and machine learning techniques to extract HRs from radar signals. The approach is validated on a sleep dataset (62 users, 498 h) and a meditation dataset (114 users, 1131 min). The approach achieves a mean absolute error (MAE) of 1.69 bpm and a mean absolute percentage error (MAPE) of [Formula: see text] on the sleep dataset. On the meditation dataset, the approach achieves an MAE of 1.05 bpm and a MAPE of [Formula: see text]. The recall rates for the two datasets are [Formula: see text] and [Formula: see text], respectively. This study represents the first application of the noncontact HR detection technology to sleep and meditation tracking, offering a promising alternative to wearable devices for HR monitoring during sleep and meditation.

Quantitative and Qualitative Impact of CT-Based Radiotherapy Dose Maps on Radiologists' Interpretation of Post-treatment Thoracic Surveillance Imaging

PURPOSE/OBJECTIVE(S)

For diagnostic radiologists, interpretation of surveillance imaging for oncology patients treated with radiation therapy (RT) can be challenging because (1) the imaging order may not adequately describe the radiation fields and (2) RT treatment effect and progression can appear similar. Volumetric dose visualization used for plan review is often inaccessible to radiologists. We hypothesize that displaying RT dose would improve radiologists' confidence and ability to correctly identify and distinguish irradiated targets and treatment effects.

MATERIALS/METHODS

CT images were read by a board-certified cardiothoracic radiologist and a diagnostic radiology resident. The readers interpreted pre-RT, treatment planning, and 3-4 month post-RT CT images in anonymized software sessions first without, then-after a 1 month "washout" period-with access to RT dose overlay. Six color-coded isodose lines ranging from 25% to 110% represented in absolute cGy were displayed along with a brief clinical history. RT fractionation schedules ranged in BED10 from 39 to 112.5 Gy. Readers were asked to label the treated lesion(s) and treatment effect(s), and record their confidence using a Likert scale of 1-5 and agreement with statements using yes/no responses.

RESULTS

Two readersindependently interpreted imaging for 32 patients who received thoracic RT to 1-5 lesion(s) for primary (24) or metastatic (8) cancer. Nineteen patients had 1 lesion and 13 patients had >1 lesion. Correct identification of all treated lesions significantly increased with the addition of dose visualization (61% to 81%; McNemar test, p = 0.00079), with the largest increase noted for cases with >1 lesion (15% to 54%; McNemar test, p = 0.0039). With the addition of dose information, the number of false negatives attributable to missed extranodal targets fell from 52% to 18%. Without dose information, 13% of labeled lesions and treatment effects fell outside of the 25% isodose lines, representing false positives. With the addition of dose information, false positives fell below 2% for both lesions and treatment effects. The readers' confidence that they had identified treated lesion(s) increased from a rating of 4.1 to 4.8 on a scale of 1-5 (Paired two-tail t test; p = 0.000005).

CONCLUSION

Whendiagnostic radiologists have access to dose visualization, correct identification rate of irradiated lesions and treatment effects, as well as confidence in these identifications significantly increased. The decrease in false negatives could reduce potential missed identification of tumor progression while the decrease in false positives could reduce inaccurate identification of treatment failure in a new or stable lesion. Our results demonstrate that adding volumetric visualization of dose to imaging could improve quality of surveillance care for patients with irradiated thoracic malignancies.

Suboptimal control status of young hypertensive population

The prevalence of hypertension (HT) among young adults aged 18 to 39 years is estimated to be 3.7% to 8.6% worldwide. Although the prevalence of HT in young adults is lower than that of the overall population, those with HT are at substantially increased risk of cardiovascular events compared to those without HT. HT in young adults should be taken with even more caution as longer exposure to higher blood pressure leads to a higher lifetime risk of HT-mediated organ damage. However, young patients with HT show low awareness of HT compared to older patients. Also, they are more prone to show low treatment adherence despite the good efficacy of the treatment. Other risk factors that hinder HT control among young adults include alcohol intake, smoking, low physical activity, emotional stress, job stress, metabolic syndrome, and obesity. This review aimed to illustrate the suboptimal control status of the young hypertensive population and to propose strategies for improvement.

VEGFA mRNA-LNP promotes biliary epithelial cell-to-hepatocyte conversion in acute and chronic liver diseases and reverses steatosis and fibrosis

The liver is known for its remarkable regenerative ability through proliferation of hepatocytes. Yet, during chronic injury or severe hepatocyte death, proliferation of hepatocytes is exhausted. To overcome this hurdle, we propose vascular-endothelial-growth-factor A (VEGFA) as a therapeutic means to accelerate biliary epithelial cell (BEC)-to-hepatocyte conversion. Investigation in zebrafish establishes that blocking VEGF receptors abrogates BEC-driven liver repair, while VEGFA overexpression promotes it. Delivery of VEGFA via non-integrative and safe nucleoside-modified mRNA encapsulated into lipid-nanoparticles (mRNA-LNP) in acutely or chronically injured mouse livers induces robust BEC-to-hepatocyte conversion and reversion of steatosis and fibrosis. In human and murine diseased livers, we further identified VEGFA-receptor KDR-expressing BECs associated with KDR-expressing cell-derived hepatocytes. This defines KDR-expressing cells, most likely being BECs, as facultative progenitors. This study reveals novel therapeutic benefits of VEGFA delivered via nucleoside-modified mRNA-LNP, whose safety is widely validated with COVID-19 vaccines, for harnessing BEC-driven repair to potentially treat liver diseases.

Highlights

Complementary mouse and zebrafish models of liver injury demonstrate the therapeutic impact of VEGFA-KDR axis activation to harness BEC-driven liver regeneration.VEGFA mRNA LNPs restore two key features of the chronic liver disease in humans such as steatosis and fibrosis.Identification in human cirrhotic ESLD livers of KDR-expressing BECs adjacent to clusters of KDR+ hepatocytes suggesting their BEC origin.KDR-expressing BECs may represent facultative adult progenitor cells, a unique BEC population that has yet been uncovered.

Hepatocyte-to-cholangiocyte conversion occurs through transdifferentiation independently of proliferation in zebrafish

BACKGROUND AND AIMS

Injury to biliary epithelial cells (BECs) lining the hepatic bile ducts leads to cholestatic liver diseases. Upon severe biliary damage, hepatocytes can convert to BECs, thereby contributing to liver recovery. Given a potential of augmenting this hepatocyte-to-BEC conversion as a therapeutic option for cholestatic liver diseases, it will be important to thoroughly understand the cellular and molecular mechanisms of the conversion process.

APPROACH AND RESULTS

Towards this aim, we have established a zebrafish model for hepatocyte-to-BEC conversion by employing Tg(fabp10a:CFP-NTR) zebrafish with a temporal inhibition of Notch signaling during regeneration. Cre/loxP-mediated permanent and H2B-mCherry-mediated short-term lineage tracing revealed that in the model, all BECs originate from hepatocytes. During the conversion, BEC markers are sequentially induced in the order of Sox9b, Yap/Taz, Notch activity/ epcam , and Alcama/ krt18 ; the expression of the hepatocyte marker Bhmt disappears between the Sox9b and Yap/Taz induction. Importantly, live time-lapse imaging unambiguously revealed transdifferentiation of hepatocytes into BECs: hepatocytes convert to BECs without transitioning through a proliferative intermediate state. In addition, using compounds and transgenic and mutant lines that modulate Notch and Yap signaling, we found that both Notch and Yap signaling are required for the conversion even in Notch- and Yap-overactivating settings.

CONCLUSIONS

Hepatocyte-to-BEC conversion occurs through transdifferentiation independently of proliferation, and Notch and Yap signaling control the process in parallel with a mutually positive interaction. The new zebrafish model will further contribute to a thorough understanding of the mechanisms of the conversion process.

In vivo imaging of calcium dynamics in zebrafish hepatocytes

BACKGROUND AND AIMS

Hepatocytes were the first cell type for which oscillations of cytoplasmic calcium levels in response to hormones were described. Since then, investigation of calcium dynamics in liver explants and culture has greatly increased our understanding of calcium signaling. A bottleneck, however, exists in observing calcium dynamics in a noninvasive manner because of the optical inaccessibility of the mammalian liver. Here, we aimed to take advantage of the transparency of the zebrafish larvae to image hepatocyte calcium dynamics in vivo at cellular resolution.

APPROACH AND RESULTS

We developed a transgenic model expressing a calcium sensor, GCaMP6s, specifically in zebrafish hepatocytes. Using this, we provide a quantitative assessment of intracellular calcium dynamics during multiple contexts, including growth, feeding, ethanol-induced stress, and cell ablation. Specifically, we show that synchronized calcium oscillations are present in vivo , which are lost upon starvation. Starvation induces lipid accumulation in the liver. Feeding recommences calcium waves in the liver, but in a spatially restricted manner, as well as resolves starvation-induced hepatic steatosis. By using a genetically encoded scavenger for calcium, we show that dampening of calcium signaling accelerates the accumulation of starvation-related lipid droplets in the liver. Furthermore, ethanol treatment, as well as cell ablation, induces calcium flux, but with different dynamics. The former causes asynchronous calcium oscillations, whereas the latter leads to a single calcium spike.

CONCLUSIONS

We demonstrate the presence of oscillations, waves, and spikes in vivo . Calcium waves are present in response to nutrition and negatively regulate starvation-induced accumulation of lipid droplets.

Update on Hepatobiliary Plasticity

The liver field has been debating for decades the contribution of the plasticity of the two epithelial compartments in the liver, hepatocytes and biliary epithelial cells (BECs), to derive each other as a repair mechanism. The hepatobiliary plasticity has been first observed in diseased human livers by the presence of biphenotypic cells expressing hepatocyte and BEC markers within bile ducts and regenerative nodules or budding from strings of proliferative BECs in septa. These observations are not surprising as hepatocytes and BECs derive from a common fetal progenitor, the hepatoblast, and, as such, they are expected to compensate for each other's loss in adults. To investigate the cell origin of regenerated cell compartments and associated molecular mechanisms, numerous murine and zebrafish models with ability to trace cell fates have been extensively developed. This short review summarizes the clinical and preclinical studies illustrating the hepatobiliary plasticity and its potential therapeutic application.

Environment-Adaptive Object Detection Framework for Autonomous Mobile Robots

Object detection is an essential function for mobile robots, allowing them to carry out missions efficiently. In recent years, various deep learning models based on convolutional neural networks have achieved good performance in object detection. However, in cases in which robots have to carry out missions in a particular environment, utilizing a model that has been trained without considering the environment in which robots must conduct their tasks degrades their object detection performance, leading to failed missions. This poor model accuracy occurs because of the class imbalance problem, in which the occurrence frequencies of the object classes in the training dataset are significantly different. In this study, we propose a systematic solution that can solve the class imbalance problem by training multiple object detection models and using these models effectively for robots that move through various environments to carry out missions. Moreover, we show through experiments that the proposed multi-model-based object detection framework with environment-context awareness can effectively overcome the class imbalance problem. As a result of the experiment, CPU usage decreased by 45.49% and latency decreased by more than 60%, while object detection accuracy increased by 6.6% on average.

Prevalence of modifiable risk factors and related poor cardiovascular outcomes following atrial fibrillation ablation

Background

Atrial fibrillation (AF) has become a global epidemic. Early catheter ablation and therapies modifying risk factors (RF) have been shown to improve outcomes of AF ablation. However, the time invested in pursuing risk factor modification may delay ablation, which could negate the procedural benefit.

Purpose

This study sought to investigate the prevalence and impact of potentially modifiable RF among AF patients undergoing catheter ablation in clinical practice.

Methods

This retrospective study included 724 consecutive patients undergoing AF ablation at a tertiary care center from 2012–2019. Pre-specified modifiable risks were examined, including the time from AF diagnosis to ablation, fluctuation/increase in BMI &gt;5% prior to ablation, mean systolic/diastolic blood pressure &gt;125/80 mmHg, obstructive sleep apnea with CPAP noncompliance, hyperlipidemia without statin therapy, tobacco use, excessive alcohol use, and diabetes mellitus with hemoglobin A1c (HbA1c) &gt;6.5%. The primary outcome was a composite of recurrent atrial arrhythmias, cardiovascular (CV) hospitalizations and mortality following AF ablation. A multivariate analysis was performed.

Results

The mean age was 61±10 years old, 32.5% were female and 72.2% had persistent AF. Many study patients had modifiable RF, ranging from 4.7% with excessive alcohol use to 64.0% experiencing delayed AF ablation. The mean time from AF diagnosis to ablation was 4.7 years. During a mean follow-up of 1.6 years after ablation, 467 (64.5%) patients met the primary outcome. Independent RF for the primary outcome were an increase/fluctuation in BMI &gt;5% (adjusted hazard ratio [AHR] 1.31, 95% confidence interval [CI] 1.07–1.60; P=0.008), diabetes with HbA1c &gt;6.5% (AHR 1.50, 95% CI 1.09–2.03; P=0.014) and hyperlipidemia without statin therapy (AHR 1.30, 95% CI 1.08–1.57; P=0.005). Delayed AF ablation over 1.5 years did not alter the outcome, Figure 1.

Conclusion

Substantial portions of patients undergoing AF ablation have potentially modifiable RF. Increased or fluctuating BMI, diabetes with HbA1c &gt;6.5%, and hyperlipidemia not treated with statin therapy portend an increased risk of recurrent atrial arrhythmia, CV hospitalizations and mortality. These findings underscore an importance pursuing RF management in patients with AF to reduce adverse outcomes after ablation.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The Jensen Family Research Sponsorship at the University of Nebraska Medical Center

Ethmoidal and maxillary nerve block versus systemic opioid administration during rhinoscopy in dogs: a non-randomised clinical trial

OBJECTIVES

This study aimed to evaluate the clinical effects of ethmoidal and maxillary nerve blocks during rhinoscopy in dogs.

MATERIALS AND METHODS

Fourteen dogs underwent rhinoscopy. Under general anaesthesia with isoflurane, ethmoidal and maxillary nerve blocks were applied bilaterally using 2% lidocaine before rhinoscopy in eight dogs (EM group). Six dogs were premedicated with hydromorphone (0.05 mg/kg) as a substitute for local nerve block (H group). During rhinoscopy, the heart rate, arterial blood pressure and end-tidal isoflurane concentration were recorded. The vaporizer setting was adjusted to increase the end-tidal isoflurane concentration when reflex movement was caused by nasal stimulation.

RESULTS

The H group, compared to the EM group, had an increase in HR that was 18 beats/minute (95% CI: 11 to 26) higher, an increase in SAP that was 22 mmHg (12 to 31) higher, an increase in MAP that was 15 mmHg (7 to 23) higher, an increase in DAP that was 12 mmHg (5 to 19) higher, and an increase in end-tidal isoflurane concentration that was 0.4% (0.3 to 0.5) higher. Head movement due to endoscope insertion was observed in 5/6 dogs (83.3%) in the H group and 1/8 dogs (12.5%) in the EM group (odds ratio, 0.029; ra95% CI, 0.001-0.574).

CLINICAL SIGNIFICANCE

Compared with administration of 0.05 mg/kg hydromorphone, concurrent block of the ethmoidal and maxillary nerves can reduce the cardiovascular response, reflex movement and anaesthetic requirement during rhinoscopy in dogs.

AB0922 Psoriatic Arthritis Disease Activity Differs by Race/Ethnicity

Background

Psoriatic arthritis (PsA) affects up to 30% of individuals with psoriasis. Studies have demonstrated that the presenting disease severity and quality of life impact of psoriasis differs by race/ethnicity in patients with and without PsA, but little is known about disease activity among different racial/ethnic groups [1-3].

Objectives

The objective of our study was to evaluate disease activity by race/ethnicity among patients with PsA.

Methods

We performed a cross-sectional study of adult (≥18 years old) patients with PsA who had at least one outpatient visit within the University of Pennsylvania health system between 2010 and 2019. Patients with PsA were identified by the presence of at least two International Classification of Diseases (ICD)-9 or ICD-10 codes for PsA associated with two different healthcare encounters. The primary outcome was disease activity as measured by the Routine Assessment of Patient Index Data 3 (RAPID3) assessment. The RAPID3 score is a validated patient-reported measure of physical function, pain, and global status [4]. RAPID3 scores range from 0 to 30, with higher scores indicating greater disease activity. Patients were included if they had at least one documented RAPID3 score. For patients with multiple RAPID3 scores, the median value was used. The primary independent variable was race/ethnicity categorized as White (reference), Black, Asian, Hispanic, or other race. Multivariable linear regression was used to assess the relationship between race/ethnicity and RAPID 3 score.

Results

The study population included 742 patients. Mean (standard deviation [SD]) age was 47.2 (13.3) years and 57.4% were female. The racial/ethnic distribution was 79.4% White, 7.0% Black, 5.0% Asian, 3.1% Hispanic, 2.6% other race, and 3.0% missing race/ethnicity. The means of the median Rapid3 scores were statistically significantly different across racial/ethnic groups (p<.001): White mean (SD) 9.79 (6.02), Black mean (SD) 14.86 (14.86), Asian mean (SD) 9.79 (5.44), Hispanic mean (SD) 15.09 (7.11), other race mean (SD) 10.57 (6.91). In an adjusted multivariable model controlling for other sociodemographic factors, body mass index, treatment history, and medical comorbidity, Hispanic patients had higher RAPID3 scores compared to White patients, indicating greater disease activity (β 3.36; 95% confidence interval [CI] 1.04 – 5.67, p <.005). In exploratory stratified analyses to evaluate effect modification by sex, among males, Black (β 3.43; 95% CI 0.23 – 6.63, p=.04) and Hispanic (β 5.94; 95% CI 2.18 – 9.70, p <.005) patients had higher RAPID3 scores than White patients. Among females, no significant racial/ethnic differences in RAPID3 scores were identified.

Conclusion

Black and Hispanic patients report greater disease activity as indicated by higher RAPID3 scores compared to White patients. Larger studies are necessary to confirm our findings and understand the causes of racial/ethnic differences in disease activity among patients with PsA.

References

[1]Abrouk M, Lee K, Brodsky M, Nakamura M, Singh R, Zhu TH, et al. Ethnicity affects the presenting severity of psoriasis. J Am Acad Dermatol. 2017;77(1):180-2.

[2]Shah SK, Arthur A, Yang YC, Stevens S, Alexis AF. A retrospective study to investigate racial and ethnic variations in the treatment of psoriasis with etanercept. J Drugs Dermatol. 2011;10(8):866-72.

[3]Takeshita J, Augustin M, de Jong E, Lafferty K, Langholff W, Langley R, Leonardi C, Menter A, Alexis A. Psoriasis-Related Quality-of-Life Differs by Race/Ethnicity. J Invest Dermatol. 2019; 139(5S, Supplement 1):S148.

[4]Coates LC, Tillett W, Shaddick G, Pincus T, Kavanaugh A, Helliwell PS. Value of the Routine Assessment of Patient Index Data 3 in Patients With Psoriatic Arthritis: Results From a Tight-Control Clinical Trial and an Observational Cohort. Arthritis Care Res (Hoboken). 2018;70(8):1198-1205.

Disclosure of Interests

Fahad Ahmed: None declared, Alexis Ogdie Consultant of: A. Ogdie has received consulting fees from Amgen, AbbVie, Bristol Myers Squibb, Celgene, CorEvitas (formerly Corrona), Gilead, Janssen, Lilly, Novartis, Pfizer, and UCB., Grant/research support from: A. Ogdie has received grant support from the National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases, Rheumatology Research Foundation, National Psoriasis Foundation, Abbvie (University of Pennsylvania), Pfizer (University of Pennsylvania), Amgen (FORWARD), and Novartis (FORWARD)., Robert Fitzsimmons: None declared, Daniel Shin: None declared, Junko Takeshita Consultant of: JT has served as a consultant for Pfizer Inc. and Janssen Biotech receiving honoraria., Grant/research support from: JT has received a research grant (to the Trustees of the University of Pennsylvania) from Pfizer Inc.

POS1049 ASSESSING TREATMENT PATTERNS WITH DISEASE-MODIFYING ANTIRHEUMATIC DRUGS AND PREDNISONE FOR PSORIATIC ARTHRITIS BY RACE/ETHNICITY

Background

Psoriatic arthritis (PsA) is a comorbidity commonly associated with psoriasis. Studies have demonstrated delays in the diagnosis and treatment of PsA[1] that may disproportionately affect racial/ethnic minority patients as indicated by one study that found Black Medicaid patients with PsA to be less likely to receive disease-modifying antirheumatic drugs [DMARDs] than White Medicaid patients with PsA [2]. Yet much remains unknown about potential racial/ethnic disparities in PsA management.

Objectives

The objective of our study was to evaluate treatment patterns for PsA by race/ethnicity.

Methods

We performed a cross-sectional study of adult (≥18 years old) patients with PsA who had at least one outpatient visit within the University of Pennsylvania health system between 2010 and 2019. Patients with PsA were identified by the presence of at least two International Classification of Diseases (ICD)-9 or ICD-10 codes for PsA associated with two different healthcare encounters. The primary outcomes were receipt of a prescription for: (i) an oral DMARD, (ii) a biologic DMARD, and (iii) prednisone. Oral DMARDs included apremilast, methotrexate, sulfasalazine, leflunomide, azathioprine, cyclosporine, tofacitinib, hydroxychloroquine, and upadacitnib. Biologic DMARDs included abatacept, adalimumab, brodalumab, certolizumab, etanercept, golimumab, guselkumab, infliximab, ixekixumab, secukinumab, ustekinumab, and risankizumab. The primary independent variable was race/ethnicity categorized as White (reference), Black, Asian, Hispanic, or other race. Multivariable logistic regression was used to assess the relationship between race/ethnicity and each treatment outcome.

Results

The study population included 1781 patients with PsA who were a mean age of 50.7 (SD 14.3), 54.6% female, and 72.5% commercially insured. The racial/ethnic distribution was 81.9% White, 5.6% Black, 4.0% Asian, 3.0% Hispanic, 2.5% other race, and 3.1% missing race/ethnicity. Of these patients, 64.3% were prescribed an oral DMARD, 55.6% were prescribed a biologic, and 44.1% were prescribed prednisone. There were no statistically significant differences across race/ethnicity for prescription of either oral or biologic DMARDs. However, prescription of prednisone did differ by race/ethnicity (p<.005) with Black (54.6%) and Hispanic (56.6%) patients being more likely to receive prednisone prescriptions and Asian (32.4%) patients being less likely to receive prednisone prescriptions than White (44.2%) patients. In adjusted logistic regression models controlling for sociodemographic and other factors, Hispanic patients were more likely to receive a prednisone prescription (OR 1.79, 95% CI 1.01 – 3.20, p=0.05) while Asian (OR 0.58, 95% CI 0.34 – 0.97, p=0.04) patients were less likely to receive a prednisone prescription compared to White patients.

Conclusion

We found Hispanic patients with PsA to be more likely to receive prednisone prescriptions than White patients with PsA but did not identify any racial/ethnic differences in prescription patterns for oral or biologic DMARDs for PsA. Greater use of prednisone among Hispanic patients may reflect different diseases trajectories (e.g., more disease flares or greater disease severity) or other factors that affect prescription patterns that require further study.

References

[1]Favier G, Gladman DD, Merola JF, Armstrong AW, Boehncke WH, Helliwell PS. Benchmarking Care in Psoriatic Arthritis - The QUANTUM Report: A Report from the GRAPPA 2016 Annual Meeting. J Rheumatol. 2017;44(5):674-678.

[2]Ogdie A, Matthias W, Thielen RJ, Chin D, Saffore CD. Racial Differences in Prevalence and Treatment for Psoriatic Arthritis and Ankylosing Spondylitis by Insurance Coverage in the USA. Rheumatol Ther. 2021;8(4):1725-1739.

Disclosure of Interests

Fahad Ahmed: None declared, Alexis Ogdie Consultant of: A. Ogdie has received consulting fees from Amgen, AbbVie, Bristol Myers Squibb, Celgene, CorEvitas (formerly Corrona), Gilead, Janssen, Lilly, Novartis, Pfizer, and UCB., Grant/research support from: A. Ogdie has received grant support from the National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases, Rheumatology Research Foundation, National Psoriasis Foundation, Abbvie (University of Pennsylvania), Pfizer (University of Pennsylvania), Amgen (FORWARD), and Novartis (FORWARD)., Robert Fitzsimmons: None declared, Daniel Shin: None declared, Junko Takeshita Consultant of: JT has served as a consultant for Pfizer Inc. and Janssen Biotech receiving honoraria., Grant/research support from: JT has received a research grant (to the Trustees of the University of Pennsylvania) from Pfizer Inc.

Pre-ablation interatrial conduction delay or block predicts atrial fibrillation recurrence after ablation among obese patients

Funding Acknowledgements

Type of funding sources: None.

Background

Obesity is associated with greater risk of atrial fibrillation (AF) recurrence post-ablation and higher incidence of conduction delay compared to non-obese patients. Pre-ablation P-wave duration (PWD) and morphology (PWM) indicating interatrial delay are easily assessed in the clinic and may predict AF recurrence post-ablation in these patients.

Purpose

Evaluate the predictive value of PWD and PWM on AF recurrence post-ablation in obese patients.

Methods

Pre-ablation PWD and PWM (negative P-wave in lead II or III) were analyzed on consecutive patients with BMI ≥30 kg/m2 who underwent initial AF ablation from 2012–19. The primary outcome was recurrent AF after a 3-month post-ablation blanking period. Multivariate analysis adjusted for baseline characteristics was performed.

Results

For 205 patients (61.0±9.5 years old, 39.0% female), mean BMI was 36.9±5.7 kg/m2 and 71.7% had persistent AF pre-ablation. Recurrent AF post-ablation occurred in 115 (56.1%) during a median follow up of 491 (270, 1001) days. PWD &gt;130 ms was significantly associated with higher AF recurrence (AHR of 1.62, 95%CI 1.04-2.57, p=0.03) after adjusting for age, persistent AF and left atrial volume index (LAVI). In a subgroup with LAVI &lt;42 mL/m2 (n=112), PWD &gt;130 ms and negative P-waves in lead II or III were independently associated with increased risk of recurrent AF (AHR 2.06, 95%CI 1.12-3.91; p=0.019 and AHR 1.94, 95% CI 1.00-3.56; p=0.05, respectively) (Figure 1).

Conclusion

AF recurred in &gt;50% of obese patients within 1.5 years of ablation. Pre-ablation PWD &gt;130 ms and negative P-waves in lead II or III independently predicted recurrent AF post-ablation in this cohort of obese patients. These easily assessed findings add predictive value to other risk factors.

Simultaneous oxidation and analysis of TOC-TN-TP in one pot reactor

Total organic carbon (TOC), total nitrogen (TN), and total phosphorous (TP) are the most common indicators of water quality. The analytical processes of the indicators require oxidation of any type of C, N, and P to carbon dioxide, nitrate, and phosphate as final products. Persulfate is the recommended oxidant for these transformations. In this study, co-oxidation was suggested for the simultaneous analysis of TOC-TN-TP. A single oxidizing reactor using persulfate was proposed instead of three individual systems. The system oxidizes complex organic chemicals to carbon dioxide, nitrate, and phosphate. However, the residual persulfate after oxidation interferes with the spectrophotometric analysis of nitrate and phosphate. Therefore, in the proposed system, the complete transformation of persulfate is a key factor for simultaneous analysis. In this system, ultraviolet irradiation for 30 min under alkaline conditions converted residual persulfate to sulfate. The complete transformation eliminated persulfate interference in nitrate and phosphate detection. In the proposed system with a single oxidation reactor, TOC, TN, and TP were oxidized and analyzed simultaneously within 15% of the analytical error range compared to the standard test method.

Follistatin-controlled activin-HNF4α-coagulation factor axis in liver progenitor cells determines outcome of acute liver failure

BACKGROUND AND AIMS

In patients with acute liver failure (ALF) who suffer from massive hepatocyte loss, liver progenitor cells (LPCs) take over key hepatocyte functions, which ultimately determines survival. This study investigated how the expression of hepatocyte nuclear factor 4α (HNF4α), its regulators, and targets in LPCs determines clinical outcome of patients with ALF.

APPROACH AND RESULTS

Clinicopathological associations were scrutinized in 19 patients with ALF (9 recovered and 10 receiving liver transplantation). Regulatory mechanisms between follistatin, activin, HNF4α, and coagulation factor expression in LPC were investigated in vitro and in metronidazole-treated zebrafish. A prospective clinical study followed up 186 patients with cirrhosis for 80 months to observe the relevance of follistatin levels in prevalence and mortality of acute-on-chronic liver failure. Recovered patients with ALF robustly express HNF4α in either LPCs or remaining hepatocytes. As in hepatocytes, HNF4α controls the expression of coagulation factors by binding to their promoters in LPC. HNF4α expression in LPCs requires the forkhead box protein H1-Sma and Mad homolog 2/3/4 transcription factor complex, which is promoted by the TGF-β superfamily member activin. Activin signaling in LPCs is negatively regulated by follistatin, a hepatocyte-derived hormone controlled by insulin and glucagon. In contrast to patients requiring liver transplantation, recovered patients demonstrate a normal activin/follistatin ratio, robust abundance of the activin effectors phosphorylated Sma and Mad homolog 2 and HNF4α in LPCs, leading to significantly improved coagulation function. A follow-up study indicated that serum follistatin levels could predict the incidence and mortality of acute-on-chronic liver failure.

CONCLUSIONS

These results highlight a crucial role of the follistatin-controlled activin-HNF4α-coagulation axis in determining the clinical outcome of massive hepatocyte loss-induced ALF. The effects of insulin and glucagon on follistatin suggest a key role of the systemic metabolic state in ALF.

Changing demographics, temporal trend in waitlist and post-transplant outcomes after heart transplantation in the United States: analysis of unos database 1991–2019

Background

The landscape of heart transplantation (HT) has changed significantly with respect to patient selection, surgical techniques, and patient outcomes. We sought to investigate temporal trends in patient characteristics, waitlist and post-transplant outcomes after HT in the U.S.

Methods

We queried the national database of the United Network of Organ Sharing (UNOS) to identify adults listed for HT in the U.S. between 1991 and 2019. Patients were divided into four eras based on the three time points in which changes were made to the patient selection/allocation policy (1999, 2006, and 2018), and patient characteristics as well as waitlist and post-transplant outcomes were evaluated for each era.

Results

Between 1991 and 2019, a total of 95,179 patients were added to the waitlist for HT in the U.S. Compared to era 1, patients listed in era 4 were older (mean age: 52.4 years), more female (27.6%) and ethnic minorities (40%), and with higher-risk comorbidities (28.8% diabetes, 35.6% obese). Over the study period, there were 22,070 waitlist deaths and 61,687 transplants.

Compared to the preceding era, there was significant decrease in waitlist mortality in the last 2 eras (e.g., sub-hazard ratio for era 4 vs era 3 =0.37, 95% CI=0.32–0.44). For each year, only 27.1% to 40.5% of those on the waitlist were transplanted. Among those who were transplanted, there was increase in the rates of in-hospital stroke (2.8% in era 1 to 3.7% in era 4), renal failure requiring dialysis (7.2% to 17.1%), and hospital length of stay (14 to 17 days), p-values&lt;0.001 for all. However, this has not negatively impacted short-term survival when compared to the preceding era (1-year graft survival = 89.7% in era 4). Based on a projection model, we predict a 47% increase in living adult heart transplant recipients to to 44,366 in 2040.

Conclusion

There have been significant changes in the characteristics of patients listed for HT in the U.S., including an increasing proportion of high-risk co-morbidities. Although the transplant volume has increased, the wide supply-demand gap persisted. The last 2 changes in the allocation policy in 2006 and 2018 achieved their primary objective of reducing waitlist mortality.

Funding Acknowledgement

Type of funding sources: None.

β-Catenin-NF-κB-CFTR interactions in cholangiocytes regulate inflammation and fibrosis during ductular reaction

Expansion of biliary epithelial cells (BECs) during ductular reaction (DR) is observed in liver diseases including cystic fibrosis (CF), and associated with inflammation and fibrosis, albeit without complete understanding of underlying mechanism. Using two different genetic mouse knockouts of β-catenin, one with β-catenin loss is hepatocytes and BECs (KO1), and another with loss in only hepatocytes (KO2), we demonstrate disparate long-term repair after an initial injury by 2-week choline-deficient ethionine-supplemented diet. KO2 show gradual liver repopulation with BEC-derived β-catenin-positive hepatocytes and resolution of injury. KO1 showed persistent loss of β-catenin, NF-κB activation in BECs, progressive DR and fibrosis, reminiscent of CF histology. We identify interactions of β-catenin, NFκB, and CF transmembranous conductance regulator (CFTR) in BECs. Loss of CFTR or β-catenin led to NF-κB activation, DR, and inflammation. Thus, we report a novel β-catenin-NFκB-CFTR interactome in BECs, and its disruption may contribute to hepatic pathology of CF.

The liver has an incredible capacity to repair itself or ‘regenerate’ – that is, it has the ability to replace damaged tissue with new tissue. In order to do this, the organ relies on hepatocytes (the cells that form the liver) and bile duct cells (the cells that form the biliary ducts) dividing and transforming into each other to repair and replace damaged tissue, in case the insult is dire.

During long-lasting or chronic liver injury, bile duct cells undergo a process called ‘ductular reaction’, which causes the cells to multiply and produce proteins that stimulate inflammation, and can lead to liver scarring (fibrosis). Ductular reaction is a hallmark of severe liver disease, and different diseases exhibit ductular reactions with distinct features. For example, in cystic fibrosis, a unique type of ductular reaction occurs at late stages, accompanied by both inflammation and fibrosis. Despite the role that ductular reaction plays in liver disease, it is not well understood how it works at the molecular level.

Hu et al. set out to investigate how a protein called β-catenin – which can cause many types of cells to proliferate – is involved in ductular reaction. They used three types of mice for their experiments: wild-type mice, which were not genetically modified; and two strains of genetically modified mice. One of these mutant mice did not produce β-catenin in biliary duct cells, while the other lacked β-catenin both in biliary duct cells and in hepatocytes.

After a short liver injury – which Hu et al. caused by feeding the mice a specific diet – the wild-type mice were able to regenerate and repair the liver without exhibiting any ductular reaction. The mutant mice that lacked β-catenin in hepatocytes showed a temporary ductular reaction, and ultimately repaired their livers by turning bile duct cells into hepatocytes. On the other hand, the mutant mice lacking β-catenin in both hepatocytes and bile duct cells displayed sustained ductular reactions, inflammation and fibrosis, which looked like that seen in patients with liver disease associated to cystic fibrosis. Further probing showed that β-catenin interacts with a protein called CTFR, which is involved in cystic fibrosis. When bile duct cells lack either of these proteins, another protein called NF-B gets activated, which causes the ductular reaction, leading to inflammation and fibrosis.

The findings of Hu et al. shed light on the role of β-catenin in ductular reaction. Further, the results show a previously unknown interaction between β-catenin, CTFR and NF-B, which could lead to better treatments for cystic fibrosis in the future.

Farnesoid X Receptor Activation Impairs Liver Progenitor Cell-Mediated Liver Regeneration via the PTEN-PI3K-AKT-mTOR Axis in Zebrafish

BACKGROUND AND AIMS

Following mild liver injury, pre-existing hepatocytes replicate. However, if hepatocyte proliferation is compromised, such as in chronic liver diseases, biliary epithelial cells (BECs) contribute to hepatocytes through liver progenitor cells (LPCs), thereby restoring hepatic mass and function. Recently, augmenting innate BEC-driven liver regeneration has garnered attention as an alternative to liver transplantation, the only reliable treatment for patients with end-stage liver diseases. Despite this attention, the molecular basis of BEC-driven liver regeneration remains poorly understood.

APPROACH AND RESULTS

By performing a chemical screen with the zebrafish hepatocyte ablation model, in which BECs robustly contribute to hepatocytes, we identified farnesoid X receptor (FXR) agonists as inhibitors of BEC-driven liver regeneration. Here we show that FXR activation blocks the process through the FXR-PTEN (phosphatase and tensin homolog)-PI3K (phosphoinositide 3-kinase)-AKT-mTOR (mammalian target of rapamycin) axis. We found that FXR activation blocked LPC-to-hepatocyte differentiation, but not BEC-to-LPC dedifferentiation. FXR activation also suppressed LPC proliferation and increased its death. These defects were rescued by suppressing PTEN activity with its chemical inhibitor and ptena/b mutants, indicating PTEN as a critical downstream mediator of FXR signaling in BEC-driven liver regeneration. Consistent with the role of PTEN in inhibiting the PI3K-AKT-mTOR pathway, FXR activation reduced the expression of pS6, a marker of mTORC1 activation, in LPCs of regenerating livers. Importantly, suppressing PI3K and mTORC1 activities with their chemical inhibitors blocked BEC-driven liver regeneration, as did FXR activation.

CONCLUSIONS

FXR activation impairs BEC-driven liver regeneration by enhancing PTEN activity; the PI3K-AKT-mTOR pathway controls the regeneration process. Given the clinical trials and use of FXR agonists for multiple liver diseases due to their beneficial effects on steatosis and fibrosis, the detrimental effects of FXR activation on LPCs suggest a rather personalized use of the agonists in the clinic.

Residual functional SYNTAX score by quantitative flow ratio and improvement of exercise capacity after revascularization in patients with stable ischemic heart disease

Background

In patients with stable ischemic heart disease (SIHD), the efficacy of percutaneous coronary intervention (PCI) in improving exercise capacity has been under debate and the differential effect of PCI for exercise capacity, according to functional completeness of revascularization, has not been evaluated.

Purpose

This study aimed to evaluate the association between improvement in exercise capacity and functional completeness of revascularization, determined by residual functional SYNTAX score (rFSS), which is the sum of residual SYNTAX score of the vessels with post-PCI quantitative flow ratio (QFR)≤0.80.

Methods

Among patients enrolled in the QFR multicenter registry, 110 patients who underwent prespecified routine exercise treadmill tests before and after PCI were analyzed. Patients were classified into functional complete revascularization (CR) group (rFSS=0) and functional incomplete revascularization (IR) group (rFSS≥1). Increase of exercise time after PCI was compared between the 2 groups. Improvement of exercise capacity was defined as ≥10% increase of exercise time after PCI.

Results

Functional CR was achieved in 79 patients (71.8%), otherwise classified as functional IR in 31 patients (18.2%). There were no significant differences in baseline characteristics including medication profiles. Increase of exercise time was significantly associated with increase of 3-vessel QFR (r=0.198, P=0.038) and rFSS (r=−0.312, P&lt;0.001), but not with decrease of SYNTAX score (r=0.097, P=0.313). The rFSS showed significantly higher c-index to predict the improvement of exercise capacity after PCI than increase of 3-vessel QFR or decrease of SYNTAX score (0.722 vs. 0.627 vs. 0.492, respectively, P&lt;0.001). Patients with functional CR, defined by rFSS, showed significantly higher increase of exercise time than those with functional IR (97.7 sec vs. 12.5 sec, P&lt;0.001). Functional CR was an independent predictor of the improvement of exercise capacity after PCI (adjusted odds ratio 4.656, 95% CI 1.678–12.920, P=0.002).

Conclusions

Integrated anatomic and functional scoring system (rFSS) was significantly associated with improvement of exercise capacity after PCI. SIHD patients with functional CR, defined by rFSS, showed significantly higher exercise capacity after PCI than those with functional IR.

Summarizing Figure

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): SaeHan NK & D and Medis Corporation

Biliary-Atresia-Associated Mannosidase-1-Alpha-2 Gene Regulates Biliary and Ciliary Morphogenesis and Laterality

Background/Aims

Infectious and genetic factors are invoked, respectively in isolated biliary atresia (BA), or syndromic BA, with major extrahepatic anomalies. However, isolated BA is also associated with minor extrahepatic gut and cardiovascular anomalies and multiple susceptibility genes, suggesting common origins.

Methods

We investigated novel susceptibility genes with genome-wide association, targeted sequencing and tissue staining in BA requiring liver transplantation, independent of BA subtype. Candidate gene effects on morphogenesis, developmental pathways, and ciliogenesis, which regulates left-right patterning were investigated with zebrafish knockdown and mouse knockout models, mouse airway cell cultures, and liver transcriptome analysis.

Results

Single nucleotide polymorphisms in Mannosidase-1-α-2 (MAN1A2) were significantly associated with BA and with other polymorphisms known to affect MAN1A2 expression but were not differentially enriched in either BA subtype. In zebrafish embryos, man1a2 knockdown caused poor biliary network formation, ciliary dysgenesis in Kupffer’s vesicle, cardiac and liver heterotaxy, and dysregulated egfra and other developmental genes. Suboptimal man1a2 knockdown synergized with suboptimal EGFR signaling or suboptimal knockdown of the EGFR pathway gene, adenosine-ribosylation-factor-6, which had minimal effects individually, to reproduce biliary defects but not heterotaxy. In cultured mouse airway epithelium, Man1a2 knockdown arrested ciliary development and motility. Man1a2^–/– mice, which experience respiratory failure, also demonstrated portal and bile ductular inflammation. Human BA liver and Man1a2^–/– liver exhibited reduced Man1a2 expression and dysregulated ciliary genes, known to cause multisystem human laterality defects.

Conclusion

BA requiring transplantation associates with sequence variants in MAN1A2. man1a2 regulates laterality, in addition to hepatobiliary morphogenesis, by regulating ciliogenesis in zebrafish and mice, providing a novel developmental basis for multisystem defects in BA.

Systems Analysis of Biliary Atresia Through Integration of High-Throughput Biological Data

Biliary atresia (BA), blockage of the proper bile flow due to loss of extrahepatic bile ducts, is a rare, complex disease of the liver and the bile ducts with unknown etiology. Despite ongoing investigations to understand its complex pathogenesis, BA remains the most common cause of liver failure requiring liver transplantation in children. To elucidate underlying mechanisms, we analyzed the different types of high-throughput genomic and transcriptomic data collected from the blood and liver tissue samples of children suffering from BA. Through use of a novel integrative approach, we identified potential biomarkers and over-represented biological functions and pathways to derive a comprehensive network showing the dysfunctional mechanisms associated with BA. One of the pathways highlighted in the integrative network was hypoxia signaling. Perturbation with hypoxia inducible factor activator, dimethyloxalylglycine, induced the biliary defects of BA in a zebrafish model, serving as a validation for our studies. Our approach enables a systems-level understanding of human BA biology that is highlighted by the interaction between key biological functions such as fibrosis, inflammation, immunity, hypoxia, and development.

Liver progenitor cell-driven liver regeneration

The liver is a highly regenerative organ, but its regenerative capacity is compromised in severe liver diseases. Hepatocyte-driven liver regeneration that involves the proliferation of preexisting hepatocytes is a primary regeneration mode. On the other hand, liver progenitor cell (LPC)-driven liver regeneration that involves dedifferentiation of biliary epithelial cells or hepatocytes into LPCs, LPC proliferation, and subsequent differentiation of LPCs into hepatocytes is a secondary mode. This secondary mode plays a significant role in liver regeneration when the primary mode does not effectively work, as observed in severe liver injury settings. Thus, promoting LPC-driven liver regeneration may be clinically beneficial to patients with severe liver diseases. In this review, we describe the current understanding of LPC-driven liver regeneration by exploring current knowledge on the activation, origin, and roles of LPCs during regeneration. We also describe animal models used to study LPC-driven liver regeneration, given their potential to further deepen our understanding of the regeneration process. This understanding will eventually contribute to developing strategies to promote LPC-driven liver regeneration in patients with severe liver diseases.

Attenuating the Epidermal Growth Factor Receptor-Extracellular Signal-Regulated Kinase-Sex-Determining Region Y-Box 9 Axis Promotes Liver Progenitor Cell-Mediated Liver Regeneration in Zebrafish

BACKGROUND AND AIMS

The liver is a highly regenerative organ, but its regenerative capacity is compromised in severe liver injury settings. In chronic liver diseases, the number of liver progenitor cells (LPCs) correlates proportionally to disease severity, implying that their inefficient differentiation into hepatocytes exacerbates the disease. Moreover, LPCs secrete proinflammatory cytokines; thus, their prolonged presence worsens inflammation and induces fibrosis. Promoting LPC-to-hepatocyte differentiation in patients with advanced liver disease, for whom liver transplantation is currently the only therapeutic option, may be a feasible clinical approach because such promotion generates more functional hepatocytes and concomitantly reduces inflammation and fibrosis.

APPROACH AND RESULTS

Here, using zebrafish models of LPC-mediated liver regeneration, we present a proof of principle of such therapeutics by demonstrating a role for the epidermal growth factor receptor (EGFR) signaling pathway in differentiation of LPCs into hepatocytes. We found that suppression of EGFR signaling promoted LPC-to-hepatocyte differentiation through the mitogen-activated ERK kinase (MEK)-extracellular signal-regulated kinase (ERK)-sex-determining region Y-box 9 (SOX9) cascade. Pharmacological inhibition of EGFR or MEK/ERK promoted LPC-to-hepatocyte differentiation as well as genetic suppression of the EGFR-ERK-SOX9 axis. Moreover, Sox9b overexpression in LPCs blocked their differentiation into hepatocytes. In the zebrafish liver injury model, both hepatocytes and biliary epithelial cells contributed to LPCs. EGFR inhibition promoted the differentiation of LPCs regardless of their origin. Notably, short-term treatment with EGFR inhibitors resulted in better liver recovery over the long term.

CONCLUSIONS

The EGFR-ERK-SOX9 axis suppresses LPC-to-hepatocyte differentiation during LPC-mediated liver regeneration. We suggest EGFR inhibitors as a proregenerative therapeutic drug for patients with advanced liver disease.