Regulation of PGC1α Downstream of the Insulin Signaling Pathway Plays a Role in the Hepatic Proteotoxicity of Mutant α1-Antitrypsin Deficiency Variant Z.

BACKGROUND & AIMS: Insulin signaling is known to regulate essential proteostasis mechanisms. METHODS: The analyses here examined effects of insulin signaling in the PiZ mouse model of α1-antitrypsin deficiency in which hepatocellular accumulation and proteotoxicity of the misfolded α1-antitrypsin Z variant (ATZ) causes liver fibrosis and cancer. RESULTS: We first studied the effects of breeding PiZ mice to liver-insulin-receptor knockout (LIRKO) mice (with hepatocyte-specific insulin-receptor gene disruption). The results showed decreased hepatic ATZ accumulation and liver fibrosis in PiZ x LIRKO vs PiZ mice, with reversal of those effects when we bred PiZ x LIRKO mice onto a FOXO1-deficient background. Increased intracellular degradation of ATZ mediated by autophagy was identified as the likely mechanism for diminished hepatic proteotoxicity in PiZ x LIRKO mice and the converse was responsible for enhanced toxicity in PiZ x LIRKO x FOXO1-KO animals. Transcriptomic studies showed major effects on oxidative phosphorylation and autophagy genes, and significant induction of peroxisome proliferator-activated-receptor-γ-coactivator-1α (PGC1α) expression in PiZ-LIRKO mice. Because PGC1α plays a key role in oxidative phosphorylation, we further investigated its effects on ATZ proteostasis in our ATZ-expressing mammalian cell model. The results showed PGC1α overexpression or activation enhances autophagic ATZ degradation. CONCLUSIONS: These data implicate suppression of autophagic ATZ degradation by down-regulation of PGC1α as one mechanism by which insulin signaling exacerbates hepatic proteotoxicity in PiZ mice, and identify PGC1α as a novel target for development of new human α1-antitrypsin deficiency liver disease therapies.

Multidisciplinary Care for Refractory Pediatric Functional Abdominal Pain Decreases Emergency and Inpatient Utilization.

ABSTRACT: Children with refractory functional abdominal pain (FAP) experience functional disability and may utilize emergency department (ED) and/or inpatient services. Whether multidisciplinary programs which help care for children with refractory FAP affect acute healthcare utilization is unknown. A retrospective chart review of children initially evaluated by the outpatient Multidisciplinary Abdominal Pain Program (MAPP) from October 2016 to May 2019 was completed. Patient characteristics and number of ED visits and hospitalizations for abdominal pain in the year prior to versus year after MAPP evaluation were captured. Thirty-eight children (ages 9-17 years [median 13 years]) were included. The median number of ED visits/patient/year decreased from 1 (range: 0-7) to 0 (range: 0-3) (P < 0.0001). Seven (18%) children had been hospitalized and, in these children, the median number of hospitalizations/patient/year decreased from 1 (range: 1-5) to 0 (range: 0-1) (P < 0.05). These data suggest multidisciplinary outpatient intervention for refractory FAP is associated with significant decreases in acute healthcare utilization.

Foxl1-Cre-marked adult hepatic progenitors have clonogenic and bilineage differentiation potential.

Isolation of hepatic progenitor cells is a promising approach for cell replacement therapy of chronic liver disease. The winged helix transcription factor Foxl1 is a marker for progenitor cells and their descendants in the mouse liver in vivo. Here, we purify progenitor cells from Foxl1-Cre; RosaYFP mice and evaluate their proliferative and differentiation potential in vitro. Treatment of Foxl1-Cre; RosaYFP mice with a 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet led to an increase of the percentage of YFP-labeled Foxl1(+) cells. Clonogenic assays demonstrated that up to 3.6% of Foxl1(+) cells had proliferative potential. Foxl1(+) cells differentiated into cholangiocytes and hepatocytes in vitro, depending on the culture condition employed. Microarray analyses indicated that Foxl1(+) cells express stem cell markers such as Prom1 as well as differentiation markers such as Ck19 and Hnf4a. Thus, the Foxl1-Cre; RosaYFP model allows for easy isolation of adult hepatic progenitor cells that can be expanded and differentiated in culture.

Alcaligenes faecalis Cellulitis After a Dog Bite: Case Report and Literature Review.

Alcaligenes faecalis is a gram-negative organism that is commonly found in the environment and may also be a part of normal fecal flora in humans. Although various infections with this bacteria have been described in the pediatric population, it has not been previously identified in infections as the pathogen after a dog bite. A case of a 19-month-old boy is presented with a cellulitis secondary to a dog bite, which failed oral antibiotic therapy, and progressed to worsening fever and swelling. The patient ultimately required hospitalization, intravenous antibiotics, and incision and drainage. The wound culture grew A. faecalis, whose identity was confirmed through recombinant DNA sequence analysis. Although it has been identified in cat bite wounds, A. faecalis has not been cited in the literature before in an infection after a dog bite.

Spontaneous Subclavian Vein Thrombosis in a Healthy Adolescent Cheerleader: A Case of Paget-Schroetter Syndrome.

We present the case of a healthy 13-year-old female adolescent who developed acute progressive swelling and pain in her right upper extremity that was secondary to an acute deep venous thrombosis of her right subclavian vein. Dynamic imaging revealed subclavian vein compression at the junction of the first rib and proximal third of the clavicle consistent with Paget-Schroetter syndrome, also known as effort-related thrombosis. The compressive etiology of her thrombus was most likely related to her cheerleading activity, in which she served as the pyramid base. The patient received multimodal therapy including anticoagulation, mechanical and site-directed thrombolysis, and a first rib resection. This case illustrates that frontline providers should have a high index of suspicion for an upper extremity thrombosis in pediatric patients who present with unilateral arm swelling.

Is severe progressive liver disease caused by alpha-1-antitrypsin deficiency more common in children or adults?

The classical form of alpha-1-antitrypsin deficiency (A1ATD) is known to cause liver disease in children and adults, but there is relatively little information about the risk of severe, progressive liver disease and the need for liver transplantation. To better understand how newly evolving pharmacological, genetic, and cellular therapies may be targeted according to risk for progressive liver disease, we sought to determine the age distribution of A1ATD as a cause of severe liver disease, as defined by the need for liver transplantation. Using 3 US liver transplantation databases for the period 1991-2012, we found 77.2% of 1677 liver transplants with a reported diagnosis of A1ATD were adults. The peak age range was 50-64 years. Using 2 of the databases which included specific A1AT phenotypes, we found that many of these adults who undergo liver transplantation with A1ATD as the diagnosis are heterozygotes and have other potential causes of liver disease, most notably obesity and ethanol abuse. However, even when these cases are excluded and only ZZ and SZ phenotypes are considered, severe liver disease requiring transplantation is more than 2.5 times as likely in adults. The analysis also showed a markedly increased risk for males. In the pediatric group, almost all of the transplants are done in children less than 5 years of age. In conclusion, A1ATD causes progressive liver disease most commonly in adults with males in the highest risk category. In the pediatric group, children less than 5 years of age are highest in risk. These results suggest that A1ATD most commonly causes liver disease by mechanisms similar to age-dependent degenerative diseases and more rarely in children by powerful modifiers. Liver Transplantation 22 886-894 2016 AASLD.

A Healthy Infant With an Ulcerated Genital Lesion: Diagnostic and Therapeutic Considerations.

We present the case of a 1-year-old healthy boy who was taking oral antibiotics for an otitis media and then developed an erythematous penile lesion that rapidly became ulcerated. He was admitted to the hospital for further diagnostic studies and intravenous therapy, and his wound culture grew Pseudomonas aeruginosa, consistent with the diagnosis of ecthyma gangrenosum. Serial blood counts also demonstrated a progressive neutropenia, and an immunodeficiency evaluation resulted in the diagnosis of autoimmune neutropenia of childhood. This case illustrates the importance of culturing wounds and the need for clinicians to recognize the characteristic features of ecthyma gangrenosum, to initiate appropriate antipseudomonal antibiotic therapy empirically, and to evaluate for a possible immunodeficiency, even in the apparently healthy child.

Acute disseminated encephalomyelitis following meningoencephalitis: case report and literature review.

Meningoencephalitis and acute disseminated encephalomyelitis (ADEM) are both neurological disease processes, but there have been few cases of meningoencephalitis progressing to ADEM in the pediatric population. A case of a 4-year-old girl with an initial diagnosis of meningoencephalitis is presented here, whose initial presentation was manifested by prolonged fever, gray matter signal abnormality on brain magnetic resonance imaging, cerebrospinal fluid pleocytosis, and a markedly irritable mental status. As her neurological examination changed with focal abnormalities, a repeat magnetic resonance imaging demonstrated new areas of both gray and white matter signal abnormality, consistent with ADEM. Her symptoms and imaging findings completely resolved with a course of methylprednisolone. Based on the literature and this current case, it is our recommendation to consider ADEM as a diagnosis if meningoencephalitis is not improving.

Cholangiocyte cilia are abnormal in syndromic and non-syndromic biliary atresia.

Biliary atresia (BA) is a neonatal disorder characterized by aggressive fibroinflammatory obliteration of the biliary tract. Approximately 20 percent of BA patients demonstrate left-right laterality defects (syndromic BA). Cilia participate in important physiological functions in cholangiocytes, and as some ciliopathies have been associated with both laterality defects and hepatic fibrosis, we hypothesized that patients with syndromic BA exhibit abnormalities of cholangiocyte cilia that disrupt cholangiocyte homeostasis. Nine BA specimens were studied, including pre-Kasai diagnostic biopsies (n=7) and liver explants (n=2). Five specimens were from patients with laterality defects. These were compared with normal pediatric livers, as well as livers affected by primary sclerosing cholangitis, Wilson's disease, and cardiac cirrhosis. Biopsy sections were stained with antibodies against keratin 19 (a cholangiocyte marker) and acetylated α-tubulin (a cilia marker) and were visualized by confocal microscopy. Computer-assisted relative quantification was used to compare staining of cilia within bile ducts among samples. Surprisingly, cilia in BA specimens were significantly shorter, abnormal in their orientation, and less abundant compared with normal liver and disease controls regardless of the presence of a laterality defect. There are significant abnormalities of cholangiocyte cilia in both syndromic and non-syndromic BA livers compared with normal livers and livers affected by other cholestatic diseases. Although this may result from severe cholestasis or inflammation, it may also reflect common mechanistic pathways in different forms of BA and may have important implications for understanding the progression of the disease.

Lineage tracing demonstrates no evidence of cholangiocyte epithelial-to-mesenchymal transition in murine models of hepatic fibrosis.

UNLABELLED: Whether or not cholangiocytes or their hepatic progenitors undergo an epithelial-to-mesenchymal transition (EMT) to become matrix-producing myofibroblasts during biliary fibrosis is a significant ongoing controversy. To assess whether EMT is active during biliary fibrosis, we used Alfp-Cre × Rosa26-YFP mice, in which the epithelial cells of the liver (hepatocytes, cholangiocytes, and their bipotential progenitors) are heritably labeled at high efficiency with yellow fluorescent protein (YFP). Primary cholangiocytes isolated from our reporter strain were able to undergo EMT in vitro when treated with transforming growth factor-ß1 alone or in combination with tumor necrosis factor-α, as indicated by adoption of fibroblastoid morphology, intracellular relocalization of E-cadherin, and expression of α-smooth muscle actin (α-SMA). To determine whether EMT occurs in vivo, we induced liver fibrosis in Alfp-Cre × Rosa26-YFP mice using the bile duct ligation (BDL) (2, 4, and 8 weeks), carbon tetrachloride (CCl(4) ) (3 weeks), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC; 2 and 3 weeks) models. In no case did we find evidence of colocalization of YFP with the mesenchymal markers S100A4, vimentin, α-SMA, or procollagen 1α2, although these proteins were abundant in the peribiliary regions. CONCLUSION: Hepatocytes and cholangiocytes do not undergo EMT in murine models of hepatic fibrosis.

A role for microRNA in cystic liver and kidney diseases.

The polycystic liver and kidney diseases are a family of disorders with heterogeneous etiologies. Proposed mechanisms of disease include ciliary dysfunction, excess cell proliferation, and altered cell-cell or cell-matrix interactions. In this issue of the JCI, Lee and colleagues provide data to support a novel mechanism for cystogenesis involving microRNA (miRNA) (see the related article beginning on page 3714). They demonstrate that levels of the miRNA miR15a are decreased in livers of patients with autosomal recessive and autosomal dominant polycystic kidney disease (ARPKD and ADPKD, respectively) and congenital hepatic fibrosis as well as in the PKC rat model of ARPKD. This results in increased expression of the cell-cycle regulator Cdc25A, which is a direct target of miR15a, and increased cellular proliferation and cystogenesis in vitro. These findings suggest that other miRNAs may also participate in the molecular pathogenesis of cystic liver and kidney diseases.

An analog of glibenclamide selectively enhances autophagic degradation of misfolded α1-antitrypsin Z.

The classical form of α1-antitrypsin deficiency (ATD) is characterized by intracellular accumulation of the misfolded variant α1-antitrypsin Z (ATZ) and severe liver disease in some of the affected individuals. In this study, we investigated the possibility of discovering novel therapeutic agents that would reduce ATZ accumulation by interrogating a C. elegans model of ATD with high-content genome-wide RNAi screening and computational systems pharmacology strategies. The RNAi screening was utilized to identify genes that modify the intracellular accumulation of ATZ and a novel computational pipeline was developed to make high confidence predictions on repurposable drugs. This approach identified glibenclamide (GLB), a sulfonylurea drug that has been used broadly in clinical medicine as an oral hypoglycemic agent. Here we show that GLB promotes autophagic degradation of misfolded ATZ in mammalian cell line models of ATD. Furthermore, an analog of GLB reduces hepatic ATZ accumulation and hepatic fibrosis in a mouse model in vivo without affecting blood glucose or insulin levels. These results provide support for a drug discovery strategy using simple organisms as human disease models combined with genetic and computational screening methods. They also show that GLB and/or at least one of its analogs can be immediately tested to arrest the progression of human ATD liver disease.

Capitalizing on the autophagic response for treatment of liver disease caused by alpha-1-antitrypsin deficiency and other genetic diseases.

Alpha-1-antitrypsin deficiency (ATD) is one of the most common genetic causes of liver disease and is a prototype of liver diseases caused by the pathologic accumulation of aggregated mutant alpha-1-antitrypsin Z (ATZ) within liver cells. In the case of ATD-associated liver disease, the resulting "gain-of-function" toxicity can lead to serious clinical manifestations, including cirrhosis and hepatocellular carcinoma. Currently, the only definitive therapy for ATD-associated liver disease is liver transplantation, but recent efforts have demonstrated the exciting potential for novel therapies that target disposal of the mutant protein aggregates by harnessing a cellular homeostasis mechanism called autophagy. In this review, we will summarize research advances on autophagy and genetic liver diseases. We will discuss autophagy enhancer strategies for liver disease due to ATD and another genetic liver disease, inherited hypofibrinogenemia, caused by the proteotoxic effects of a misfolded protein. On the basis of recent evidence that autophagy plays a role in cellular lipid degradation, we also speculate about autophagy enhancer strategies for treatment of hepatic lipid storage diseases such as cholesterol ester storage disease.