Alpha1-antitrypsin deficiency in 26-year-old subjects: lung, liver, and protease/protease inhibitor studies

Liver Disorders Caused by Inborn Errors of Metabolism

Inborn errors of metabolism (IEMs) are a vast array of inherited/congenital disorders, affecting a wide variety of metabolic pathways and/or biochemical processes inside the cells. Although IEMs are usually rare, they can be represented as serious health problems. During the neonatal period, these inherited defects can give rise to almost all key signs of liver malfunction, including jaundice, coagulopathy, hepato- and splenomegaly, ascites, etc. Since the liver is a vital organ with multiple synthetic, metabolic, and excretory functions, IEM-related hepatic dysfunction could seriously be considered life-threatening. In this context, the identification of those hepatic manifestations and their associated characteristics may promote the differential diagnosis of IEMs immediately after birth, making therapeutic strategies more successful in preventing the occurrence of subsequent events. Among all possible liver defects caused by IEMs, cholestatic jaundice, hepatosplenomegaly, and liver failure have been shown to be manifested more frequently. Therefore, the current study aims to review substantial IEMs that mostly result in the aforementioned hepatic disorders, relying on clinical principles, especially through the first years of life. In this article, a group of uncommon hepatic manifestations linked to IEMs is also discussed in brief.

Nine controversial questions about augmentation therapy for alpha-1 antitrypsin deficiency: a viewpoint

Augmentation therapy with intravenous alpha-1 antitrypsin is the only specific treatment for alpha-1 antitrypsin deficiency (AATD)-associated emphysema. This treatment has been available and remained basically unchanged for more than 35 years, but many questions persist regarding its indications, regimen of administration and efficacy. Because AATD is a rare disease, it has not been possible to conduct randomised, placebo-controlled trials that are adequately powered for the usual outcomes analysed in non-AATD-related COPD, such as lung function decline, exacerbations, symptoms or quality of life. New outcomes such as lung densitometry measured by computed tomography are more sensitive for identifying emphysema progression but are not widely accepted by regulatory agencies. In addition, clinical manifestations, severity and the natural history of lung disease associated with AATD are very heterogeneous, which means that individual prediction of prognosis is challenging. Therefore, the indication for augmentation is sometimes a dilemma between initiating treatment in individuals who may not develop significant lung disease or in whom disease will not progress and delaying it in patients who will otherwise rapidly and irreversibly progress.Other areas of debate are the possible indication for augmentation in patients with severe AATD and respiratory diseases other than emphysema, such as bronchiectasis or asthma, and the use of therapy after lung transplant in AATD patients. All these uncertainties imply that the indication for treatment must be personalised in expert reference centres after in-depth discussion of the pros and cons of augmentation with the patient.

The investigation of the frequency of the alpha-1-antitrypsin phenotype in patients with liver cirrhosis

OBJECTIVES

Alpha-1-antitrypsin (AAT) has different phenotypes. Evidence suggests that the abundance of each of these phenotypes may be associated with a disease. The purpose of this study was to evaluate the frequency of AAT phenotypes in patients with liver cirrhosis as well as in healthy individuals.

METHODS

In this study, 42 patients with liver cirrhosis were selected. The results of the previous research done by the researcher on healthy individuals were used to construct the control group. After obtaining informed consent, 5 mL of fasting venous blood sample was taken, and phenotypes were analyzed by isoelectric focusing. Data were analyzed using Chi-square and Fisher's exact tests at a significant level of 0.05.

RESULTS

The results of this study indicated that all 42 healthy subjects had an MM allele (100%). However, among 42 patients, 35 (83.3%) had an MM allele, 5 (11.9%) had an MS allele, and 2 (4.8%) had MZ allele. The difference between the two groups was significant (p=0.02). There was no difference between men and women in the allele type (p=0.557).

CONCLUSIONS

This study revealed that MS and MZ alleles were observed only in patients with liver cirrhosis, and none of these alleles were found in healthy subjects. Therefore, MS and MZ alleles can be further investigated as risk factors for liver cirrhosis.

Living with the enemy: from protein-misfolding pathologies we know, to those we want to know

Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.

Up-regulation of miR-34b/c by JNK and FOXO3 protects from liver fibrosis

α1-Antitrypsin (AAT) deficiency is a common genetic disease presenting with lung and liver diseases. AAT deficiency results from pathogenic variants in the SERPINA1 gene encoding AAT and the common mutant Z allele of SERPINA1 encodes for Z α1-antitrypsin (ATZ), a protein forming hepatotoxic polymers retained in the endoplasmic reticulum of hepatocytes. PiZ mice express the human ATZ and are a valuable model to investigate the human liver disease of AAT deficiency. In this study, we investigated differential expression of microRNAs (miRNAs) between PiZ and control mice and found that miR-34b/c was up-regulated and its levels correlated with intrahepatic ATZ. Furthermore, in PiZ mouse livers, we found that Forkhead Box O3 (FOXO3) driving microRNA-34b/c (miR-34b/c) expression was activated and miR-34b/c expression was dependent upon c-Jun N-terminal kinase (JNK) phosphorylation on Ser⁵⁷⁴ Deletion of miR-34b/c in PiZ mice resulted in early development of liver fibrosis and increased signaling of platelet-derived growth factor (PDGF), a target of miR-34b/c. Activation of FOXO3 and increased miR-34c were confirmed in livers of humans with AAT deficiency. In addition, JNK-activated FOXO3 and miR-34b/c up-regulation were detected in several mouse models of liver fibrosis. This study reveals a pathway involved in liver fibrosis and potentially implicated in both genetic and acquired causes of hepatic fibrosis.

Alpha-1 Antitrypsin Deficiency Liver Disease, Mutational Homogeneity Modulated by Epigenetic Heterogeneity With Links to Obesity

Alpha-1 antitrypsin deficiency (AATD) liver disease is characterized by marked heterogeneity in presentation and progression, despite a common underlying gene mutation, strongly suggesting the involvement of other genetic and/or epigenetic modifiers. Variation in clinical phenotype has added to the challenge of detection, diagnosis, and testing of new therapies in patients with AATD. We examined the contribution of DNA methylation (5-methylcytosine [5mC]) to AATD liver disease heterogeneity because 5mC responds to environmental and genetic cues and its deregulation is a major driver of liver disease. Using liver biopsies from adults with early-stage AATD and the ZZ genotype, genome-wide 5mC patterns were interrogated. We compared DNA methylation among patients with early AATD, and among patients with normal liver, cirrhosis, and hepatocellular carcinoma derived from multiple etiologic exposures, and linked patient clinical/demographic features. Global analysis revealed significant genomic hypomethylation in AATD liver-impacting genes related to liver cancer, cell cycle, and fibrosis, as well as key regulatory molecules influencing growth, migration, and immune function. Further analysis indicated that 5mC changes are localized, with hypermethylation occurring within a background of genome-wide 5mC loss and with patients with AATD manifesting distinct epigenetic landscapes despite their mutational homogeneity. By integrating clinical data with 5mC landscapes, we observed that CpGs differentially methylated among patients with AATD disease are linked to hallmark clinical features of AATD (e.g., hepatocyte degeneration and polymer accumulation) and further reveal links to well-known sex-specific effects of liver disease progression. Conclusion: Our data reveal molecular epigenetic signatures within this mutationally homogeneous group that point to ways to stratify patients for liver disease risk.

Survival in the Swedish cohort with alpha-1-antitrypsin deficiency, up to the age of 43-45 years

Background

Alpha-1-antitrypsin deficiency (AATD) is a hereditary disorder. AATD is a known risk factor for the development of emphysema and liver disease. A cohort of severe (PiZZ) and moderate (PiSZ) AAT-deficient newborn infants was identified by the Swedish national neonatal AAT screening in 1972-1974 and has been followed up since birth. Our aim was to study survival in this cohort up to 43-45 years of age in comparison with the general Swedish population.

Methods

Data from 127 PiZZ, 2 PiZnull, 54 PiSZ, and 1 PiSnull subjects, who were identified by the neonatal screening in 1972-1974, were included in the study. To compare death rates in the PiZZ and PiSZ individuals with the general Swedish population, a standardized mortality ratio (SMR) was calculated as the ratio of observed to expected deaths.

Results

Seven PiZZ subjects died during the follow-up, to be compared with an expected 3.66 deaths for the general population, giving an SMR of 1.91 (95% CI 0.77-3.94). Four PiSZ subjects died compared to an expected 1.53 deaths, giving an SMR of 2.61 (95% CI 0.71-6.71). The cumulative probability of survival up to the age of 45 years was 94% (95% CI 90%-98%) for the study population. Six deaths occurred before the age of 8 years.

Conclusion

Up to 43-45 years of age, there was no difference in survival between PiZZ and PiSZ individuals in comparison with the Swedish general population. The majority of deaths occurred during childhood.

Alpha-1 antitrypsin deficiency: outstanding questions and future directions

Background

Alpha-1 antitrypsin deficiency (AATD) is a rare hereditary condition that leads to decreased circulating alpha-1 antitrypsin (AAT) levels, significantly increasing the risk of serious lung and/or liver disease in children and adults, in which some aspects remain unresolved.

Methods

In this review, we summarise and update current knowledge on alpha-1 antitrypsin deficiency in order to identify and discuss areas of controversy and formulate questions that need further research.

Results

1) AATD is a highly underdiagnosed condition. Over 120,000 European individuals are estimated to have severe AATD and more than 90% of them are underdiagnosed.

Conclusions

2) Several clinical and etiological aspects of the disease are yet to be resolved. New strategies for early detection and biomarkers for patient outcome prediction are needed to reduce morbidity and mortality in these patients; 3) Augmentation therapy is the only specific approved therapy that has shown clinical efficacy in delaying the progression of emphysema. Regrettably, some countries reject registration and reimbursement for this treatment because of the lack of larger randomised, placebo-controlled trials. 4) Alternative strategies are currently being investigated, including the use of gene therapy or induced pluripotent stem cells, and non-augmentation strategies to prevent AAT polymerisation inside hepatocytes.

Liver Disease in Alpha-1 Antitrypsin Deficiency: Current Approaches and Future Directions

Purpose of Review

The aim of the study is to review the liver disease caused by alpha-1 antitrypsin deficiency (A1ATD), including pathogenesis, epidemiology, diagnostic testing, and recent therapeutic developments.

Recent Findings

Therapeutic approaches target several intracellular pathways to reduce the cytotoxic effects of the misfolded mutant globular protein (ATZ) on the hepatocyte. These include promoting ATZ transport out of the endoplasmic reticulum (ER), enhancing ATZ degradation, and preventing ATZ globule-aggregation.

Summary

A1ATD is the leading genetic cause of liver disease among children. It is a protein-folding disorder in which toxic insoluble ATZ proteins aggregate in the ER of hepatocytes leading to inflammation, fibrosis, cirrhosis, and increased risk of hepatocellular carcinoma. The absence of the normal A1AT serum protein also predisposes patients to pan lobar emphysema as adults. At this time, the only approved therapy for A1ATD-associated liver disease is orthotopic liver transplantation, which is curative. However, there has been significant recent progress in the development of small molecule therapies with potential both to preserve the native liver and prevent hepatotoxicity.

Alpha-1 antitrypsin Pi*SZ genotype: estimated prevalence and number of SZ subjects worldwide

The alpha-1 antitrypsin (AAT) haplotype Pi*S, when inherited along with the Pi*Z haplotype to form a Pi*SZ genotype, can be associated with pulmonary emphysema in regular smokers, and less frequently with liver disease, panniculitis, and systemic vasculitis in a small percentage of people, but this connection is less well established. Since the detection of cases can allow the application of preventive measures in patients and relatives with this congenital disorder, the objective of this study was to update the prevalence of the SZ genotype to achieve accurate estimates of the number of Pi*SZ subjects worldwide, based on studies performed according to the following criteria: 1) samples representative of the general population, 2) AAT phenotyping characterized by adequate methods, and 3) selection of studies with reliable results assessed with a coefficient of variation calculated from the sample size and 95% confidence intervals. Studies fulfilling these criteria were used to develop tables and maps with an inverse distance-weighted (IDW) interpolation method, to provide numerical and geographical information of the Pi*SZ distribution worldwide. A total of 262 cohorts from 71 countries were included in the analysis. With the data provided by these cohorts, a total of 1,490,816 Pi*SZ were estimated: 708,792 in Europe; 582,984 in America and Caribbean; 85,925 in Africa; 77,940 in Asia; and 35,176 in Australia and New Zealand. Remarkably, the IDW interpolation maps predicted the Pi*SZ prevalence throughout the entire world even in areas lacking real data. These results may be useful to plan strategies for future research, diagnosis, and management of affected individuals.

Activation of the c-Jun N-terminal kinase pathway aggravates proteotoxicity of hepatic mutant Z alpha1-antitrypsin

Alpha1-antitrypsin deficiency is a genetic disease that can affect both the lung and the liver. The vast majority of patients harbor a mutation in the serine protease inhibitor 1A (SERPINA1) gene leading to a single amino acid substitution that results in an unfolded protein that is prone to polymerization. Alpha1-antitrypsin defciency-related liver disease is therefore caused by a gain-of-function mechanism due to accumulation of the mutant Z alpha1-antitrypsin (ATZ) and is a key example of an disease mechanism induced by protein toxicity. Intracellular retention of ATZ triggers a complex injury cascade including apoptosis and other mechanisms, although several aspects of the disease pathogenesis are still unclear. We show that ATZ induces activation of c-Jun N-terminal kinase (JNK) and c-Jun and that genetic ablation of JNK1 or JNK2 decreased ATZ levels in vivo by reducing c-Jun-mediated SERPINA1 gene expression. JNK activation was confirmed in livers of patients homozygous for the Z allele, with severe liver disease requiring hepatic transplantation. Treatment of patient-derived induced pluripotent stem cell-hepatic cells with a JNK inhibitor reduced accumulation of ATZ.

CONCLUSION

These data reveal that JNK is a key pathway in the disease pathogenesis and add new therapeutic entry points for liver disease caused by ATZ. (Hepatology 2017;65:1865-1874).

Autophagy in the liver: functions in health and disease

The concept of macroautophagy was established in 1963, soon after the discovery of lysosomes in rat liver. Over the 50 years since, studies of liver autophagy have produced many important findings. The liver is rich in lysosomes and possesses high levels of metabolic-stress-induced autophagy, which is precisely regulated by concentrations of hormones and amino acids. Liver autophagy provides starved cells with amino acids, glucose and free fatty acids for use in energy production and synthesis of new macromolecules, and also controls the quality and quantity of organelles such as mitochondria. Although the efforts of early investigators contributed markedly to our current knowledge of autophagy, the identification of autophagy-related genes represented a revolutionary breakthrough in our understanding of the physiological roles of autophagy in the liver. A growing body of evidence has shown that liver autophagy contributes to basic hepatic functions, including glycogenolysis, gluconeogenesis and β-oxidation, through selective turnover of specific cargos controlled by a series of transcription factors. In this Review, we outline the history of liver autophagy study, and then describe the roles of autophagy in hepatic metabolism under healthy and disease conditions, including the involvement of autophagy in α1-antitrypsin deficiency, NAFLD, hepatocellular carcinoma and viral hepatitis.

Bile Duct Ligation Induces ATZ Globule Clearance in a Mouse Model of α-1 Antitrypsin Deficiency

α-1 Antitrypsin deficiency (A1ATD) can progress to cirrhosis and hepatocellular carcinoma; however, not all patients are susceptible to severe liver disease. In A1ATD, a toxic gain-of-function mutation generates insoluble ATZ "globules" in hepatocytes, overwhelming protein clearance mechanisms. The relationship between bile acids and hepatocytic autophagy is less clear but may involve altered gene expression pathways. Based on previous findings that bile duct ligation (BDL) induces autophagy, we hypothesized that retained bile acids may have hepatoprotective effects in PiZZ transgenic mice, which model A1ATD. We performed BDL and partial BDL (pBDL) in PiZZ mice, followed by analysis of liver tissues. PiZZ liver subjected to BDL showed up to 50% clearance of ATZ globules, with increased expression of autophagy proteins. Analysis of transcription factors revealed significant changes. Surprisingly nuclear TFEB, a master regulator of autophagy, remained unchanged. pBDL confirmed that ATZ globule clearance was induced by localized stimuli rather than diet or systemic effects. Several genes involved in bile metabolism were overexpressed in globule-devoid hepatocytes, compared to globule-containing cells. Retained bile acids led to a dramatic reduction of ATZ globules, with enhanced hepatocyte regeneration and autophagy. These findings support investigation of synthetic bile acids as potential autophagy-enhancing agents.

Health status and lung function in the Swedish alpha 1-antitrypsin deficient cohort, identified by neonatal screening, at the age of 37-40 years

BACKGROUND

Severe alpha 1-antitrypsin (AAT) deficiency (genotype PiZZ) is a well-known risk factor for COPD. A cohort of PiZZ and PiSZ individuals was identified by the Swedish national neonatal AAT screening program in 1972-1974 and followed up regularly since birth. Our aim was to study the lung function, respiratory symptoms and health status at the age of 38 years in comparison with a random sample of control subjects selected from the population registry.

METHODS

The study group included 120 PiZZ, 46 PiSZ and 164 control subjects (PiMM), who answered a questionnaire on smoking habits and symptoms and the Saint George Respiratory Questionnaire (SGRQ) on quality of life. A total of 89 PiZZ, 33 PiSZ and 92 PiMM subjects underwent spirometry.

RESULTS

Four percent of the PiZZ, 2% of the PiSZ and 12% of the control subjects were current smokers (P=0.008), and 17% of the PiZZ, 9% of the PiSZ and 21% of the control subjects had stopped smoking. The PiZZ current smokers had a significantly higher (ie, poorer) median activity score according to the SGRQ than the PiZZ never-smokers (P=0.032). The PiMM current smokers had significantly higher activity score (P<0.001), symptom score (P<0.001), and total score (P=0.001) according to the SGRQ than the PiMM never-smokers. The PiZZ current smokers had a significantly lower postbronchodilator forced expiratory volume in 1 second (FEV1)% of predicted value (P=0.019) and FEV1/forced vital capacity (FVC) ratio (P=0.032) than the PiZZ never-smokers. The proportion of subjects with a FEV1/FVC ratio of <0.70, indicating COPD, was significantly higher in the PiZZ current smokers than in the PiZZ never-smokers (P=0.001). Among the PiSZ and PiMM subjects, the differences in lung function between the smoking subgroups were insignificant.

CONCLUSION

PiZZ current smokers were found to have signs of COPD before 40 years of age. Smoking is less common among the AAT-deficient subjects identified by neonatal screening than among their peers in the general population.

A Challenging Case of Severe Infantile Cholestasis in Alpha-1 Antitrypsin Deficiency

Jaundice in the newborn period can be physiologic and is often due to benign causes. Jaundice due to conjugated hyperbilirubinemia extending beyond the second week of life may be an early sign of several cholestatic or metabolic liver diseases, and it requires logical and timely analysis so that specific treatments can be initiated. Alpha-1 antitrypsin deficiency is the most common genetic cause of pediatric liver disease and transplantation, and it must be considered when evaluating cholestatic infants. Here, we present an unusual case of alpha-1 antitrypsin deficiency with severe infantile cholestasis and rapid decompensation in the first 4 months of life, where in-depth but timely diagnosis was crucial for the appropriate intervention to take place.

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.

Enhancing Autophagy with Drugs or Lung-directed Gene Therapy Reverses the Pathological Effects of Respiratory Epithelial Cell Proteinopathy

Recent studies have shown that autophagy mitigates the pathological effects of proteinopathies in the liver, heart, and skeletal muscle but this has not been investigated for proteinopathies that affect the lung. This may be due at least in part to the lack of an animal model robust enough for spontaneous pathological effects from proteinopathies even though several rare proteinopathies, surfactant protein A and C deficiencies, cause severe pulmonary fibrosis. In this report we show that the PiZ mouse, transgenic for the common misfolded variant α1-antitrypsin Z, is a model of respiratory epithelial cell proteinopathy with spontaneous pulmonary fibrosis. Intracellular accumulation of misfolded α1-antitrypsin Z in respiratory epithelial cells of the PiZ model resulted in activation of autophagy, leukocyte infiltration, and spontaneous pulmonary fibrosis severe enough to elicit functional restrictive deficits. Treatment with autophagy enhancer drugs or lung-directed gene transfer of TFEB, a master transcriptional activator of the autophagolysosomal system, reversed these proteotoxic consequences. We conclude that this mouse is an excellent model of respiratory epithelial proteinopathy with spontaneous pulmonary fibrosis and that autophagy is an important endogenous proteostasis mechanism and an attractive target for therapy.

Liver tumors in children with metabolic disorders

Hepatic neoplasia is a rare but serious complication of metabolic diseases in children. The risk of developing neoplasia, the age at onset, and the measures to prevent it differ in the various diseases. We review the most common metabolic disorders that are associated with a heightened risk of developing hepatocellular neoplasms, with a special emphasis on reviewing recent advances in the molecular pathogenesis of the disorders and pre-clinical therapeutic options. The cellular and genetic pathways driving carcinogenesis are poorly understood, but best understood in tyrosinemia.

[Alpha-1 antitrypsin deficiency: A model of alteration of protein homeostasis or proteostasis]

Chronic obstructive pulmonary disease (COPD) is currently the ninth leading cause of death in France and is predicted to become the third leading cause of worldwide morbidity and mortality by 2020. Risk factors for COPD include exposure to tobacco, dusts and chemicals, asthma and alpha-1 antitrypsin deficiency. This genetic disease, significantly under-diagnosed and under-recognized, affects 1 in 2500 live births and is an important cause of lung and, occasionally, liver disease. Alpha-1 antitrypsin deficiency is a pathology of proteostasis-mediated protein folding and trafficking pathways. To date, there are only palliative therapeutic approaches for the symptoms associated with this hereditary disorder. Therefore, a more detailed understanding is required of the folding and trafficking biology governing alpha-1 antitrypsin biogenesis and its response to drugs. Here, we review the cell biological, biochemical and biophysical properties of alpha-1 antitrypsin and its variants, and we suggest that alpha-1 antitrypsin deficiency is an example of cell autonomous and non-autonomous challenges to proteostasis. Finally, we review emerging strategies that may be used to enhance the proteostasis system and protect the lung from alpha-1 antitrypsin deficiency.

Alpha-1 antitrypsin deficiency and the risk of hepatocellular carcinoma in end-stage liver disease

AIM: To evaluate the association between alpha-1 antitrypsin deficiency (A1ATD) and hepatocellular carcinoma (HCC) in patients with end-stage liver disease (ESLD).

METHODS: Patients with cirrhosis and ESLD referred to the Cleveland Clinic Foundation for liver transplantation between 2003 and 2014 were included in the study (N = 675). ESLD was defined as having histological features of cirrhosis and/or radiological evidence of cirrhosis in the context of portal hypertension (ascites, variceal bleeding, thrombocytopenia, or hepatic encephalopathy). A1ATD was diagnosed using phenotype characterization (MZ or ZZ), liver biopsy detection of PAS-positive diastase-resistant (PAS+) globules, or both. Patients with other causes of liver diseases such as hepatitis C virus (HCV), alcoholic liver disease and non-alcoholic steatohepatitis (NASH) or NASH were also included in the study. HCC was diagnosed by using imaging modalities, biopsy findings, or explanted liver inspection. Follow-up time was defined as the number of years from the diagnosis of cirrhosis to the diagnosis of hepatocellular carcinoma, or from the diagnosis of cirrhosis to the last follow up visit. The rate of HCC was assessed using time-to-interval analysis for interval censored data.

RESULTS: This study included 675 patients. 7% of subjects had A1ATD (n = 47). Out of all subjects who did not have A1ATD, 46% had HCV, 17% had alcoholic liver disease, 19% had NASH and 18% had another primary diagnosis. Of the 47 subjects with A1ATD, 15 had a primary diagnosis of A1ATD (PI*ZZ phenotype and PAS+ globules), 8 had a PI*MZ phenotype alone, 14 had PAS+ alone, and 10 had both the PI*MZ phenotype and PAS+. Median follow-up time was 3.4 (25^th, 75^th percentiles: 1, 5.2) years. The overall rate of hepatocellular carcinoma in all subjects was 29% (n = 199). In the A1ATD group, the incidence rate of HCC was 8.5% compared to 31% in the group of patients with other causes of cirrhosis (P = 0.001). Patients with ESLD due to A1ATD had the lowest yearly cumulative rate of hepatocellular carcinoma at 0.88% per year compared to 2.7% for those with HCV cirrhosis, 1.5% in patients with NASH and 0.9% in alcohol-induced liver disease (P < 0.001).

CONCLUSION: Within this group of patients with ESLD, there was no significant association between A1ATD and increased risk of HCC.

[Alpha-1-antitrypsin deficiency]

Alpha-1-antitrypsin (α1AT) deficiency is a genetic disorder that manifests as pulmonary emphysema and liver cirrhosis. α1AT deficiency is the most common genetic cause of liver disease in children and also an underappreciated cause of liver disease in adults. The prevalence in the general population in Western Europe is approximately 1 in 2,000. The most common and severe deficiency allele is the Z variant (two alleles mutated). This variant is characterized by the accumulation of Z-α1AT polymers in the endoplasmic reticulum of hepatocytes leading to cell death and to a severe reduction of α1AT in the serum. The latter results in a loss of its antiprotease activity and its ability to protect lung tissue. Thus far, there are only very limited therapeutic options in α1AT deficiency. A more detailed understanding of the biology governing α1AT biogenesis is required in order to identify new pharmacological agents and biomarkers. This review will present current knowledge on α1AT deficiency and focus on recent discoveries and new strategies in the treatment of this disease.

Lung Function and CT Densitometry in Subjects with alpha-1-Antitrypsin Deficiency and Healthy Controls at 35 Years of Age

Alpha-1-antitrypsin (AAT) deficiency is a genetic risk factor for pulmonary emphysema. In 1972-74 all 200,000 Swedish new-born infants were screened for AAT deficiency. The aim of the present study was to investigate whether the PiZZ and PiSZ individuals identified by this screening have signs of emphysema and the role of smoking in this, compared with a random sample of control subjects at 35 years of age. The study participants underwent complete pulmonary function tests (PFT) and CT densitometry. The fifteenth percentile density (PD15) and the relative area below -910 HU (RA-910) were analyzed. Fifty-four PiZZ, 21 PiSZ and 66 PiMM control subjects participated in the study. No significant differences were found in lung function between the never-smoking AAT-deficient and control subjects. The 16 PiZZ ever-smokers had significantly lower carbon monoxide transfer coefficient (KCO) than the 20 PiSZ never-smokers (p = 0.014) and the 44 PiMM never-smokers (p = 0.005). After correction for the CT derived lung volume, the PiZZ ever-smokers had significantly lower PD15 (p = 0.046) than the ever-smoking controls. We conclude that 35-year-old PiZZ and PiSZ never-smokers have normal lung function when compared with never-smoking control subjects. The differences in KCO and CT densitometric parameters between the PiZZ ever-smokers and the control subjects may indicate early signs of emphysema.

PiZ mouse liver accumulates polyubiquitin conjugates that associate with catalytically active 26S proteasomes

Accumulation of aggregation-prone human alpha 1 antitrypsin mutant Z (AT-Z) protein in PiZ mouse liver stimulates features of liver injury typical of human alpha 1 antitrypsin type ZZ deficiency, an autosomal recessive genetic disorder. Ubiquitin-mediated proteolysis by the 26S proteasome counteracts AT-Z accumulation and plays other roles that, when inhibited, could exacerbate the injury. However, it is unknown how the conditions of AT-Z mediated liver injury affect the 26S proteasome. To address this question, we developed a rapid extraction strategy that preserves polyubiquitin conjugates in the presence of catalytically active 26S proteasomes and allows their separation from deposits of insoluble AT-Z. Compared to WT, PiZ extracts had about 4-fold more polyubiquitin conjugates with no apparent change in the levels of the 26S and 20S proteasomes, and unassembled subunits. The polyubiquitin conjugates had similar affinities to ubiquitin-binding domain of Psmd4 and co-purified with similar amounts of catalytically active 26S complexes. These data show that polyubiquitin conjugates were accumulating despite normal recruitment to catalytically active 26S proteasomes that were available in excess, and suggest that a defect at the 26S proteasome other than compromised binding to polyubiquitin chain or peptidase activity played a role in the accumulation. In support of this idea, PiZ extracts were characterized by high molecular weight, reduction-sensitive forms of selected subunits, including ATPase subunits that unfold substrates and regulate access to proteolytic core. Older WT mice acquired similar alterations, implying that they result from common aspects of oxidative stress. The changes were most pronounced on unassembled subunits, but some subunits were altered even in the 26S proteasomes co-purified with polyubiquitin conjugates. Thus, AT-Z protein aggregates indirectly impair degradation of polyubiquitinated proteins at the level of the 26S proteasome, possibly by inducing oxidative stress-mediated modifications that compromise substrate delivery to proteolytic core.

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.

Mysteries of α1-antitrypsin deficiency: emerging therapeutic strategies for a challenging disease

The classical form of α1-antitrypsin deficiency (ATD) is an autosomal co-dominant disorder that affects ~1 in 3000 live births and is an important genetic cause of lung and liver disease. The protein affected, α1-antitrypsin (AT), is predominantly derived from the liver and has the function of inhibiting neutrophil elastase and several other destructive neutrophil proteinases. The genetic defect is a point mutation that leads to misfolding of the mutant protein, which is referred to as α1-antitrypsin Z (ATZ). Because of its misfolding, ATZ is unable to efficiently traverse the secretory pathway. Accumulation of ATZ in the endoplasmic reticulum of liver cells has a gain-of-function proteotoxic effect on the liver, resulting in fibrosis, cirrhosis and/or hepatocellular carcinoma in some individuals. Moreover, because of reduced secretion, there is a lack of anti-proteinase activity in the lung, which allows neutrophil proteases to destroy the connective tissue matrix and cause chronic obstructive pulmonary disease (COPD) by loss of function. Wide variation in the incidence and severity of liver and lung disease among individuals with ATD has made this disease one of the most challenging of the rare genetic disorders to diagnose and treat. Other than cigarette smoking, which worsens COPD in ATD, genetic and environmental modifiers that determine this phenotypic variability are unknown. A limited number of therapeutic strategies are currently available, and liver transplantation is the only treatment for severe liver disease. Although replacement therapy with purified AT corrects the loss of anti-proteinase function, COPD progresses in a substantial number of individuals with ATD and some undergo lung transplantation. Nevertheless, advances in understanding the variability in clinical phenotype and in developing novel therapeutic concepts is beginning to address the major clinical challenges of this mysterious disorder.

[Hepatic involvement in hereditary alpha-1-antitrypsin deficiency]

Apha-1-antitrypsin deficiency is an autosomal recessive genetic disorder seen in all races. The molecular defect is a specific mutation of the SERPINA1 gene leading to synthesis of an abnormal protein (alpha-1-antitrypsin Z) that cannot be secreted and polymerizes in the endoplasmic reticulum of hepatocytes. The inter-individual variability in the responses to intracellular stress induced by the accumulation of abnormal polymers and the mechanisms allowing their degradation is, without doubt, responsible for the different clinical manifestations of the disease. The disease affects the liver where the abnormal protein is synthesized and the lung, which is its place of action. Liver involvement is well recognized in homozygous infants of the phenotype ZZ. In this situation the disease may present a varying picture from neonatal cholestasis (about 15% of neonatal defects) to cirrhosis. However, evolution towards cirrhosis affects less than 3% of infants with the ZZ phenotype and it is preceded in 80% of cases by neonatal cholestasis. In adolescents or adults the manifestations associated with alpha-1-antitrypsin deficiency are usually limited to biochemical abnormalities but may lead to cirrhosis or hepatocellular carcinoma. The hepatic disorder and its complications are treated symptomatically though the pulmonary involvement may benefit from substitution treatment. More specific treatments targeting the molecular and cellular abnormalities are the subject of research.

Targeting intracellular degradation pathways for treatment of liver disease caused by α1-antitrypsin deficiency

The classic form of α1-antitrypsin deficiency (ATD) is a well-known genetic cause of severe liver disease in childhood. A point mutation alters the folding of a hepatic secretory glycoprotein such that the protein is prone to misfolding and polymerization. Liver injury, characterized predominantly by fibrosis/cirrhosis and carcinogenesis, is caused by the proteotoxic effect of polymerized mutant α1-antitrypsin Z (ATZ), which accumulates in the endoplasmic reticulum (ER) of hepatocytes. Several intracellular pathways have been shown to be responsible for disposal of ATZ after it accumulates in the ER, but autophagy appears to be specialized for disposal of insoluble ATZ polymers. Recently, we have found that drugs that enhance the activity of the autophagic pathway reduce the cellular load of mutant ATZ and reverse hepatic fibrosis in a mouse model of ATD. Because several of these autophagy enhancers have been used safely in humans for other reasons, we have been able to initiate a clinical trial of one of these drugs, carbamazepine, to determine its efficacy in severe liver disease due to ATD. In this review, we discuss the autophagy enhancer drugs as a new therapeutic strategy that targets cell biological mechanisms integral to the pathogenesis of liver disease due to ATD.

Functions of autophagy in normal and diseased liver

Autophagy has emerged as a critical lysosomal pathway that maintains cell function and survival through the degradation of cellular components such as organelles and proteins. Investigations specifically employing the liver or hepatocytes as experimental models have contributed significantly to our current knowledge of autophagic regulation and function. The diverse cellular functions of autophagy, along with unique features of the liver and its principal cell type the hepatocyte, suggest that the liver is highly dependent on autophagy for both normal function and to prevent the development of disease states. However, instances have also been identified in which autophagy promotes pathological changes such as the development of hepatic fibrosis. Considerable evidence has accumulated that alterations in autophagy are an underlying mechanism of a number of common hepatic diseases including toxin-, drug- and ischemia/reperfusion-induced liver injury, fatty liver, viral hepatitis and hepatocellular carcinoma. This review summarizes recent advances in understanding the roles that autophagy plays in normal hepatic physiology and pathophysiology with the intent of furthering the development of autophagy-based therapies for human liver diseases.

Gene transfer of master autophagy regulator TFEB results in clearance of toxic protein and correction of hepatic disease in alpha-1-anti-trypsin deficiency

Alpha-1-anti-trypsin deficiency is the most common genetic cause of liver disease in children and liver transplantation is currently the only available treatment. Enhancement of liver autophagy increases degradation of mutant, hepatotoxic alpha-1-anti-trypsin (ATZ). We investigated the therapeutic potential of liver-directed gene transfer of transcription factor EB (TFEB), a master gene that regulates lysosomal function and autophagy, in PiZ transgenic mice, recapitulating the human hepatic disease. Hepatocyte TFEB gene transfer resulted in dramatic reduction of hepatic ATZ, liver apoptosis and fibrosis, which are key features of alpha-1-anti-trypsin deficiency. Correction of the liver phenotype resulted from increased ATZ polymer degradation mediated by enhancement of autophagy flux and reduced ATZ monomer by decreased hepatic NFκB activation and IL-6 that drives ATZ gene expression. In conclusion, TFEB gene transfer is a novel strategy for treatment of liver disease of alpha-1-anti-trypsin deficiency. This study may pave the way towards applications of TFEB gene transfer for treatment of a wide spectrum of human disorders due to intracellular accumulation of toxic proteins.

Alpha-1-antitrypsin in pathogenesis of hepatocellular carcinoma

CONTEXT

Alpha-1-antitrypsin (A1AT) is the most abundant liver-derived, highly polymorphic, glycoprotein in plasma. Hereditary deficiency of alpha-1-antitrypsin in plasma (A1ATD) is a consequence of accumulation of polymers of A1AT mutants in endoplasmic reticulum of hepatocytes and other A1AT-producing cells. One of the clinical manifestations of A1ATD is liver disease in childhood and cirrhosis and/or hepatocellular carcinoma (HCC) in adulthood. Epidemiology and pathophysiology of liver failure in early childhood caused by A1ATD are well known, but the association with hepatocellular carcinoma is not clarified. The aim of this article is to review different aspects of association between A1AT variants and hepatocellular carcinoma, with emphasis on the epidemiology and molecular pathogenesis. The significance of A1AT as a biomarker in the diagnosis of HCC is also discussed.

EVIDENCE ACQUISITIONS

Search for relevant articles were performed through Pub Med, HighWire, and Science Direct using the keywords "alpha-1-antitrypsin", "liver diseases", "hepatocellular carcinoma", "SERPINA1". Articles published until 2011 were reviewed.

RESULTS

Epidemiology studies revealed that severe A1ATD is a significant risk factor for cirrhosis and HCC unrelated to the presence of HBV or HCV infections. However, predisposition to HCC in moderate A1ATD is rare, and probably happens in combination with HBV and/or HCV infections or other unknown risk factors. It is assumed that accumulation of polymers of A1ATD variants in endoplasmic reticulum of hepatocytes leads to damage of hepatocytes by gain-of-function mechanism. Also, increased level of A1AT was recognized as diagnostic and prognostic marker of HCC.

CONCLUSIONS

Clarification of a carcinogenic role for A1ATD and identification of proinflammatory or some still unknown factors that lead to increased susceptibility to HCC associated with A1ATD may contribute to a better understanding of hepatic carcinogenesis and to the development of new drugs.

Other genetic liver diseases in children

Wilson disease is rare but proteiform, and should be suspected in any child with liver disease and older than 3 years of age. The treatment is very efficient, and must be taken life-long. Fifteen percent of patients with alpha-1-antitrypsin deficiency develop a neonatal jaundice, and 3% a cirrhosis in childhood. There is no specific treatment except liver transplantation. Five percent of cystic fibrosis patients develop a cirrhosis, with a very slow progression. Milder abnormalities are frequent, as well as biliary stones. Liver disease in ciliopathies may be a congenital hepatic fibrosis, with risks of portal hypertension and cholangitis, or a more variable biliary disease. Gilbert disease is frequent and benign. Crigler-Najjar syndrome is rare, severe, and may be an indication for liver or liver-cell transplantation.

Elastin in asthma

Extracellular matrix is generally increased in asthma, causing thickening of the airways which may either increase or decrease airway responsiveness, depending on the mechanical requirements of the deposited matrix. However, in vitro studies have shown that the altered extracellular matrix produced by asthmatic airway smooth muscle cells is able to induce increased proliferation of non-asthmatic smooth muscle cells, which is a process believed to contribute to airway hyper-responsiveness in asthma. Elastin is an extracellular matrix protein that is altered in asthmatic airways, but there has been no systematic investigation of the functional effect of these changes. This review reveals divergent reports of the state of elastin in the airway wall in asthma. In some layers of the airway it has been described as increased, decreased and/or fragmented, or unchanged. There is also considerable evidence for an imbalance of matrix metalloproteinases, which degrade elastin, and their respective inhibitors the tissue inhibitors of metalloproteinases, which collectively help to explain observations of both increased elastin and elastin fragments. A loss of lung elastic recoil in asthma suggests a mechanical role for disordered elastin in the aetiology of the disease, but extensive studies of elastin in other tissues show that elastin fragments elicit cellular effects such as increased proliferation and inflammation. This review summarises the current understanding of the role of elastin in the asthmatic airway.

Novel treatment strategies for liver disease due to α1-antitrypsin deficiency

Alpha1-antitrypsin (AT) deficiency is the most common genetic cause of liver disease in children and is also a cause of chronic hepatic fibrosis, cirrhosis, and hepatocellular carcinoma in adults. Recent advances in understanding how mutant AT molecules accumulate within hepatocytes and cause liver cell injury have led to a novel strategy for chemoprophylaxis of this liver disease. This strategy involves a class of drugs, which enhance the intracellular degradation of mutant AT and, because several of these drugs have been used safely in humans for other indications, the strategy can be moved immediately into clinical trials. In this review, we will also report on advances that provide a basis for several other strategies that could be used in the future for treatment of the liver disease associated with AT deficiency.

The role of proteases, endoplasmic reticulum stress and SERPINA1 heterozygosity in lung disease and α-1 anti-trypsin deficiency

The serine proteinase inhibitor α-1 anti-trypsin (AAT) provides an antiprotease protective screen throughout the body. Mutations in the AAT gene (SERPINA1) that lead to deficiency in AAT are associated with chronic obstructive pulmonary diseases. The Z mutation encodes a misfolded variant of AAT that is not secreted effectively and accumulates intracellularly in the endoplasmic reticulum of hepatocytes and other AAT-producing cells. Until recently, it was thought that loss of antiprotease function was the major cause of ZAAT-related lung disease. However, the contribution of gain-of-function effects is now being recognized. Here we describe how both loss- and gain-of-function effects can contribute to ZAAT-related lung disease. In addition, we explore how SERPINA1 heterozygosity could contribute to smoking-induced chronic obstructive pulmonary diseases and consider the consequences.

Performance of enhanced liver fibrosis plasma markers in asymptomatic individuals with ZZ α1-antitrypsin deficiency

OBJECTIVES

Alpha1-antitrypsin deficiency (AATD) is a common genetic cause of chronic liver disease. According to retrospective studies, up to 25% of those with homozygous ZZ (Glu 342 to Lys) AATD suffer from liver cirrhosis and/or liver cancer in late adulthood. We hypothesized that the plasma markers for liver fibrosis, necrosis, and apoptosis may identify AATD individuals at higher risk for liver diseases.

METHODS

The study cohort included 52 clinically healthy ZZ AATD individuals of 34 years of age, identified in the Swedish neonatal screening of 1972-1974, and 81 age-matched controls with normal MM AAT variant. We analyzed plasma levels of the enhanced liver fibrosis (ELF) panel, including plasma tissue inhibitor of metalloprotease-1, amino-terminal propeptide of type III collagen and hyaluronic acid (HA), and the M30 and M65 antigens, markers for apoptosis/necrosis.

RESULTS

Higher levels of tissue inhibitor of metalloprotease-1 (52%, P<0.001), amino-terminal propeptide of type III collagen (12%, P<0.05), HA (17% not significant), and M65 (13.4%, P=0.043) were found in ZZ than in MM patients. In the ZZ group, plasma levels of AAT correlated with M65 (P<0.01) and with HA (P<0.05). On the basis of the ELF panel, M30 and M65, a logistic regression model enabled us to correctly classify 81.2% of the originally grouped ZZ and MM cases with a sensitivity of 73.1% and a specificity of 86.4%.

CONCLUSION

The ELF markers are associated with ZZ AATD at early adulthood, and can be considered as a useful tool to identify ZZ cases at an increased risk of developing liver diseases later in life.

Alpha-1-antitrypsin deficiency: importance of proteasomal and autophagic degradative pathways in disposal of liver disease-associated protein aggregates

Alpha-1-antitrypsin (AT) deficiency is the most common genetic cause of liver disease in children. The primary pathological issue is a point mutation that renders an abundant hepatic secretory glycoprotein prone to altered folding and a tendency to polymerize and aggregate. However, the expression of serious liver damage among homozygotes is dependent on genetic and/or environmental modifiers. Several studies have validated the concept that endogenous hepatic pathways for disposal of aggregation-prone proteins, including the proteasomal and autophagic degradative pathways, could play a key role in the variation in hepatic damage and be the target of the modifiers. Exciting recent results have shown that a drug that enhances autophagy can reduce the hepatic load of aggregated protein and reverse fibrosis in a mouse model of this disease.

Hepatic fibrosis and carcinogenesis in α1-antitrypsin deficiency: a prototype for chronic tissue damage in gain-of-function disorders

In α1-antitrypsin (AT) deficiency, a point mutation renders a hepatic secretory glycoprotein prone to misfolding and polymerization. The mutant protein accumulates in the endoplasmic reticulum of liver cells and causes hepatic fibrosis and hepatocellular carcinoma by a gain-of-function mechanism. Genetic and/or environmental modifiers determine whether an affected homozygote is susceptible to hepatic fibrosis/carcinoma. Two types of proteostasis mechanisms for such modifiers have been postulated: variation in the function of intracellular degradative mechanisms and/or variation in the signal transduction pathways that are activated to protect the cell from protein mislocalization and/or aggregation. In recent studies we found that carbamazepine, a drug that has been used safely as an anticonvulsant and mood stabilizer, reduces the hepatic load of mutant AT and hepatic fibrosis in a mouse model by enhancing autophagic disposal of this mutant protein. These results provide evidence that pharmacological manipulation of endogenous proteostasis mechanisms is an appealing strategy for chemoprophylaxis in disorders involving gain-of-function mechanisms.

Hepatic neoplasia and metabolic diseases in children

Hepatic neoplasia is a rare but serious complication of metabolic diseases in children. The risk of developing neoplasia, the age at onset, and the measures to prevent it differ in various diseases. This article reviews the most common metabolic disorders in humans that are associated with neoplasms, with a special emphasis on the molecular etiopathogenesis of this process. The cellular pathways driving carcinogenesis are poorly understood, but best known in tyrosinemia.

Modeling inherited metabolic disorders of the liver using human induced pluripotent stem cells

Human induced pluripotent stem (iPS) cells hold great promise for advancements in developmental biology, cell-based therapy, and modeling of human disease. Here, we examined the use of human iPS cells for modeling inherited metabolic disorders of the liver. Dermal fibroblasts from patients with various inherited metabolic diseases of the liver were used to generate a library of patient-specific human iPS cell lines. Each line was differentiated into hepatocytes using what we believe to be a novel 3-step differentiation protocol in chemically defined conditions. The resulting cells exhibited properties of mature hepatocytes, such as albumin secretion and cytochrome P450 metabolism. Moreover, cells generated from patients with 3 of the inherited metabolic conditions studied in further detail (alpha1-antitrypsin deficiency, familial hypercholesterolemia, and glycogen storage disease type 1a) were found to recapitulate key pathological features of the diseases affecting the patients from which they were derived, such as aggregation of misfolded alpha1-antitrypsin in the endoplasmic reticulum, deficient LDL receptor-mediated cholesterol uptake, and elevated lipid and glycogen accumulation. Therefore, we report a simple and effective platform for hepatocyte generation from patient-specific human iPS cells. These patient-derived hepatocytes demonstrate that it is possible to model diseases whose phenotypes are caused by pathological dysregulation of key processes within adult cells.

Studies of gamma-glutamyl transferase in alpha-1 antitrypsin deficiency

Gamma-glutamyl transferase (GGT) is a clinical marker of biliary disease, but is also of importance in anti-oxidant metabolic pathways and, consequently, is a potential biomarker of oxidative stress in COPD. Serum GGT is increased in alpha-1 antitrypsin deficiency (AATD) but this could reflect a hepatic, systemic or pulmonary origin. We aimed to investigate the relationship between serum GGT, lung disease, liver disease and mortality in subjects with AATD. Serum GGT was measured at the baseline assessment in 334 PiZ subjects from the UK AATD registry, and related to static lung function, chronic bronchitis, sputum purulence, history of acute exacerbations, smoking status, mortality, alcohol consumption, cirrhosis and serum markers of liver disease. GGT correlated with airflow obstruction and was associated with chronic bronchitis. GGT levels were higher in current smokers compared with ex-smokers and never smokers, and in non-survivors compared with survivors. Although GGT related to alcohol consumption and established liver disease, it was independently related to FEV(1), mortality, smoking history and male gender. In conclusion, although serum GGT reflects the presence of liver disease it is independently associated with airflow obstruction and mortality. Further studies are needed to establish the role of GGT in oxidative lung injury, and its use as a potential biomarker in chronic inflammatory lung disease.

An autophagy-enhancing drug promotes degradation of mutant alpha1-antitrypsin Z and reduces hepatic fibrosis

In the classical form of alpha1-antitrypsin (AT) deficiency, a point mutation in AT alters the folding of a liver-derived secretory glycoprotein and renders it aggregation-prone. In addition to decreased serum concentrations of AT, the disorder is characterized by accumulation of the mutant alpha1-antitrypsin Z (ATZ) variant inside cells, causing hepatic fibrosis and/or carcinogenesis by a gain-of-toxic function mechanism. The proteasomal and autophagic pathways are known to mediate degradation of ATZ. Here we show that the autophagy-enhancing drug carbamazepine (CBZ) decreased the hepatic load of ATZ and hepatic fibrosis in a mouse model of AT deficiency-associated liver disease. These results provide a basis for testing CBZ, which has an extensive clinical safety profile, in patients with AT deficiency and also provide a proof of principle for therapeutic use of autophagy enhancers.

The liver in 30-year-old individuals with alpha(1)-antitrypsin deficiency

OBJECTIVE. Severe (PiZZ) alpha(1)-antitrypsin (AAT) deficiency is a risk factor for liver disease, i.e. juvenile cirrhosis in infancy, and cirrhosis and hepatoma in adulthood. Little is known about the risk of liver disease in individuals with moderate (PiSZ) AAT deficiency. To investigate the natural course of AAT deficiency, a cohort of PiZZ and PiSZ individuals identified by the Swedish National neonatal screening programme in 1972-74 is followed regularly. The aim of this study was to compare liver function in this cohort with healthy control subjects aged 30 years. MATERIAL AND METHODS. Blood samples were obtained from 89 PiZZ, 40 PiSZ, and 84 control subjects (PiMM), and plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl (GT) transpeptidase were analysed. RESULTS. The mean values of all liver enzymes were within the normal range in all Pi subgroups. However, the mean AST was higher in the PiZZ and PiSZ subgroups than in the PiMM subgroup (p < 0.001), and the mean ALT was higher in the PiZZ individuals than in the controls (p < 0.05), while GT did not differ significantly among the Pi subgroups. The PiZZ women taking oral contraceptives had higher mean AST and ALT (p < 0.01) and GT (p < 0.05) than the control women taking oral contraceptives. CONCLUSIONS. At the age of 30 years, PiZZ and PiSZ individuals have normal plasma levels of the transaminases AST and ALT, although they are significantly higher than those in healthy control subjects. Use of oral contraceptives seems to influence liver enzymes in PiZZ women.

Low-dose aspirin has no impact on systemic level of serine protease inhibitors in healthy volunteers

Low-dose aspirin (100 mg/day) was recently found to increase serum levels of alpha-1 protease inhibitor (A1-PI). Here, we studied the serum levels of 2 major serine protease inhibitors, A1-PI and serine leukocyte protease inhibitor (SLPI), in 10 Helicobacter pylorinegative healthy volunteers (HVs) treated with low-dose aspirin alone and in combination with other drugs.(1) Neither the treatment with low-dose aspirin alone or in combination altered serum levels of both serine protease inhibitors. The previously described increase of A1-PI levels by low-dose aspirin was most likely caused by multiple endoscopies within a few days, which caused a systemic stress response.

[Alpha-1 antitrypsin deficiency: diagnosis and treatment]

Alpha-1 antitrypsin deficiency is a recently identified genetic disease that occurs almost as frequently as cystic fibrosis. It is caused by various mutations in the SERPINA1 gene, and has numerous clinical implications. Alpha-1 antitrypsin is mainly produced in the liver and acts as an antiprotease. Its principal function is to inactivate neutrophil elastase, preventing tissue damage. The mutation most commonly associated with the clinical disease is the Z allele, which causes polymerization and accumulation within hepatocytes. The accumulation of and the consequent reduction in the serum levels of alpha-1 antitrypsin cause, respectively, liver and lung disease, the latter occurring mainly as early emphysema, predominantly in the lung bases. Diagnosis involves detection of low serum levels of alpha-1 antitrypsin as well as phenotypic confirmation. In addition to the standard treatment of chronic obstructive pulmonary disease, specific therapy consisting of infusion of purified alpha-1 antitrypsin is currently available. The clinical efficacy of this therapy, which appears to be safe, has yet to be definitively established, and its cost-effectiveness is also a controversial issue that is rarely addressed. Despite its importance, in Brazil, there are no epidemiological data on the prevalence of the disease or the frequency of occurrence of deficiency alleles. Underdiagnosis has also been a significant limitation to the study of the disease as well as to appropriate treatment of patients. It is hoped that the creation of the Alpha One International Registry will resolve these and other important issues.

Liver disease associated with ZZ alpha1-antitrypsin deficiency and ursodeoxycholic acid therapy in children

OBJECTIVES

To investigate the effect of ursodeoxycholic acid (UDCA) in children with liver disease associated with ZZ alpha1-antitrypsin (AAT) deficiency.

PATIENTS AND METHODS

A total of 42 affected children received UDCA (30 mg x kg x day(-1)) and underwent clinical and biochemical follow-up at least yearly.

RESULTS

In group 1, 22 children whose mean initial gamma-glutamyl-transpeptidase (GGT) was 7.4 x N normalized serum liver test results after a mean treatment of 2.6 years. In 16 of these children, UDCA was discontinued. Relapse was observed in 11 children, and liver test results returned to normal after UDCA resumption. In the other 5 children, liver test results remained normal during a mean period of 2.5 years. In group 2, 11 children (mean initial GGT 12.8 x N) had improved liver test results after a mean treatment of 2.3 years. In group 3, 9 children (mean initial GGT 33.8 x N) had no liver test result improvement and evolution toward cirrhosis, requiring liver transplantation in 7. Most of the children in group 1 had normal results of clinical examination after UDCA treatment, versus none in group 3 (P < or = 0.00001). Initial GGT (P < or = 0.002) and total bilirubin (P < or = 0.05) levels were significantly lower in group 1 than in group 3. Combined initial values of GGT < or =5.5 x N and total bilirubin < or =66 micromol/L were associated with normalization of liver test results in 90% of children.

CONCLUSIONS

UDCA may significantly improve clinical status and liver test results in some children with liver disease associated with ZZ AAT deficiency. No beneficial effect of UDCA was shown in children with the most severe liver involvement. Initial levels of GGT and total bilirubin may be of prognostic value for therapy effectiveness.

Autophagic disposal of the aggregation-prone protein that causes liver inflammation and carcinogenesis in alpha-1-antitrypsin deficiency

Alpha-1-antitrypsin (AT) deficiency is a relatively common autosomal co-dominant disorder, which causes chronic lung and liver disease. A point mutation renders aggregation-prone properties on a hepatic secretory protein in such a way that the mutant protein is retained in the endoplasmic reticulum of hepatocytes rather than secreted into the blood and body fluids where it ordinarily functions as an inhibitor of neutrophil proteases. A loss-of-function mechanism allows neutrophil proteases to degrade the connective tissue matrix of the lung causing chronic emphysema. Accumulation of aggregated mutant AT in the endoplasmic reticulum of hepatocytes causes liver inflammation and carcinogenesis by a gain-of-toxic function mechanism. However, genetic epidemiology studies indicate that many, if not the majority of, affected homozygotes are protected from liver disease by unlinked genetic and/or environmental modifiers. Studies performed over the last several years have demonstrated the importance of autophagy in disposal of mutant, aggregated AT and raise the possibility that predisposition to, or protection from, liver injury and carcinogenesis is determined by the balance of de novo biogenesis of the mutant AT molecule and its autophagic disposal.

Screening and familial testing of patients for alpha 1-antitrypsin deficiency

alpha(1)-Antitrypsin deficiency (AATD) is an autosomal-codominant genetic disorder that predisposes individuals to the development of liver and lung disease. AATD is greatly underrecognized and underdiagnosed. Early identification allows preventive measures to be taken, the most important of which is the avoidance of smoking (including the inhalation of second-hand smoke) and exposure to environmental pollutants. Early detection also allows careful lung function monitoring and augmentation therapy while the patient still has preserved lung function. Cost factors and controversies have discouraged the initiation of large-scale screening programs of the newborn and adult populations in the United States and Europe (except for Sweden). There are sound medical reasons for targeted screening. Evidence-based recommendations for testing have been published by the American Thoracic Society/European Respiratory Society task force, which take potential social, psychological, and ethical adverse factors into consideration. This review discusses rationales for testing and screening for AATD in asymptomatic individuals, family members, and the general population, weighing benefits against potential psychological, social, and ethical implications of testing. For most, negative issues are outweighed by the benefits of testing. AATD testing should be routine in the management of adults with emphysema, COPD, and asthma with incompletely reversible airflow obstruction.