scholarly journals The Autophagy Pathway: A Critical Route in the Disposal of Alpha 1-Antitrypsin Aggregates That Holds Many Mysteries

2021 ◽  
Vol 22 (4) ◽  
pp. 1875
Author(s):  
Celine Leon ◽  
Marion Bouchecareilh
Keyword(s):  
Liver Transplantation ◽  
Liver Disease ◽  
Therapeutic Option ◽  
Ubiquitin Proteasome System ◽  
Therapeutic Benefit ◽  
Cellular Functions ◽  
Precise Control ◽  
New Therapeutic Approaches ◽  
Alpha 1 Antitrypsin Deficiency ◽  
Alpha 1 Antitrypsin

The maintenance of proteome homeostasis, or proteostasis, is crucial for preserving cellular functions and for cellular adaptation to environmental challenges and changes in physiological conditions. The capacity of cells to maintain proteostasis requires precise control and coordination of protein synthesis, folding, conformational maintenance, and clearance. Thus, protein degradation by the ubiquitin–proteasome system (UPS) or the autophagy–lysosomal system plays an essential role in cellular functions. However, failure of the UPS or the autophagic process can lead to the development of various diseases (aging-associated diseases, cancer), thus both these pathways have become attractive targets in the treatment of protein conformational diseases, such as alpha 1-antitrypsin deficiency (AATD). The Z alpha 1-antitrypsin (Z-AAT) misfolded variant of the serine protease alpha 1-antitrypsin (AAT) is caused by a structural change that predisposes it to protein aggregation and dramatic accumulation in the form of inclusion bodies within liver hepatocytes. This can lead to clinically significant liver disease requiring liver transplantation in childhood or adulthood. Treatment of mice with autophagy enhancers was found to reduce hepatic Z-AAT aggregate levels and protect them from AATD hepatotoxicity. To date, liver transplantation is the only curative therapeutic option for patients with AATD-mediated liver disease. Therefore, the development and discovery of new therapeutic approaches to delay or overcome disease progression is a top priority. Herein, we review AATD-mediated liver disease and the overall process of autophagy. We highlight the role of this system in the regulation of Z-variant degradation and its implication in AATD-medicated liver disease, including some open questions that remain challenges in the field and require further elucidation. Finally, we discuss how manipulation of autophagy could provide multiple routes of therapeutic benefit in AATD-mediated liver disease.

scholarly journals Association between circulating alpha-1 antitrypsin polymers and lung and liver disease

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Alexa Núñez ◽  
Irene Belmonte ◽  
Elena Miranda ◽  
Miriam Barrecheguren ◽  
Georgina Farago ◽  
...  
Keyword(s):  
Liver Disease ◽  
Genetic Diseases ◽  
Sandwich Elisa ◽  
Liver Stiffness ◽  
Cross Sectional Study ◽  
Control Group ◽  
Cross Sectional ◽  
Impaired Lung Function ◽  
Alpha 1 Antitrypsin Deficiency ◽  
Alpha 1 Antitrypsin

Abstract Background Alpha-1 antitrypsin deficiency (AATD) is considered one of the most common genetic diseases and is characterised by the misfolding and polymerisation of the alpha-1 antitrypsin (AAT) protein within hepatocytes. The relevance of circulating polymers (CP) of AAT in the pathogenesis of lung and liver disease is not completely understood. Therefore, the main objective of our study was to determine whether there is an association between the levels of CP of AAT and the severity of lung and liver disease. Method This was a cross-sectional study in patients with different phenotypes of AATD and controls. To quantify CP, a sandwich ELISA was performed using the 2C1 monoclonal antibody against AAT polymers. Sociodemographic data, clinical characteristics, and liver and lung parameters were collected. Results A cohort of 70 patients was recruited: 32 Pi*ZZ (11 on augmentation therapy); 29 Z-heterozygous; 9 with other genotypes. CP were compared with a control group of 47 individuals (35 Pi*MM and 12 Pi*MS). ZZ patients had the highest concentrations of CP (p < 0.001) followed by Z heterozygous. The control group and patients with Pi*SS and Pi*SI had the lowest CP concentrations. Pi*ZZ also had higher levels of liver stiffness measurements (LSM) than the remaining AATD patients. Among patients with one or two Z alleles, two patients with lung and liver impairment showed the highest concentrations of CP (47.5 µg/mL), followed by those with only liver abnormality (n = 6, CP = 34 µg/mL), only lung (n = 18, CP = 26.5 µg/mL) and no abnormalities (n = 23, CP = 14.3 µg/mL). Differences were highly significant (p = 0.004). Conclusions Non-augmented Pi*ZZ and Z-patients with impaired lung function and increased liver stiffness presented higher levels of CP than other clinical phenotypes. Therefore, CP may help to identify patients more at risk of developing lung and liver disease and may provide some insight into the mechanisms of disease.

Alpha-1-antitrypsin deficiency: diagnosis and treatment (literature review)

2021 ◽  
pp. 12-24
Author(s):  
Е.А. Ларшина ◽  
Н.В. Милованова ◽  
Е.А. Каменец
Keyword(s):  
Liver Disease ◽  
Genetic Disorder ◽  
New Drugs ◽  
Chronic Obstructive ◽  
Diagnosis Delay ◽  
Loss Of Function ◽  
Antitrypsin Deficiency ◽  
Alpha 1 Antitrypsin Deficiency ◽  
A1at Deficiency ◽  
Alpha 1 Antitrypsin

Недостаточность альфа-1-антитрипсина - наследственное заболевание, характеризующееся низким уровнем белка альфа-1-антитрипсина (A1AT) в крови. В основном дефицит A1AT проявляется в виде хронической обструктивной болезни легких (ХОБЛ), эмфиземы, а также поражения печени и сосудов. А1АТ является главным ингибитором сериновых протеаз в крови человека. Недостаточность А1АТ обусловлена мутациями в гене SERPINA1. Наиболее распространенными аллельными вариантами в гене SERPINA1 являются S (p.Glu288Val) и Z (р.Glu366Lys), однако в клинической практике большинство случаев тяжелого дефицита А1АТ связаны с генотипом PIZZ. У пациентов с PIZZ патология легких представляет собой фенотип «потери функции», так как дефицит A1AT приводит к ускоренному разрушению паренхимы легких, приводящему к эмфиземе. При Z-мутации 85% синтезированного белка блокируется в гепатоцитах из-за неправильного сворачивания и полимеризации. Накопление полимеризованного белка в эндоплазматической сети гепатоцитов в свою очередь приводит к хроническим заболеваниям печени у некоторых пациентов: циррозу и злокачественным новообразованиям печени. Дефицит А1АТ является довольно распространенным заболеванием, но выявляется лишь незначительная часть лиц с данной патологией. Недостаточность А1АТ зачастую ошибочно диагностируется как ХОБЛ, бронхиальная астма или криптогенное заболевание печени. Задержка в установлении диагноза составляет обычно более 5 лет (в среднем около 8 лет) что, как правило, связано с плохой осведомленностью врачей, недооценкой его распространенности и вариабельностью клинических проявлений. В настоящее время для лечения дефицита А1АТ с легочными проявлениями возможно применение аугментационной терапии, основанной на внутривенном введении очищенного человеческого А1АТ. Также активно ведется поиск новых препаратов, способных улучшить прогноз у пациентов с патологией печени. Современные подходы в лечении дефицита А1АТ, сосредоточенные на генной терапии, становятся перспективным направлением в лечении как легочной, так и печеночной патологии при дефиците А1АТ. Alpha-1 antitrypsin deficiency is a genetic disorder characterized by low level of alfa-1-antitripsin protein (A1AT) in the blood. Usually, A1AT deficiency results in chronic obstructive pulmonary disease (COPD), emphysemas, liver disease and vessels damaging. A1AT is the main inhibitor of serine proteases in human blood. A1AT deficiency is caused by mutations in the gene SERPINA1. The most common SERPINA1 allelic variants are S (p.Glu288Val) and Z (p.Glu366Lys). However, the most of documented severe cases of A1AD are associated with PIZZ genotype. PIZZ genotype patients have loss-of-function phenotype due to accelerated lung parenchyma destruction resulting in emphysema. Z mutation genotype leads to blocking of 85% synthesized protein in hepatocytes due to wrong folding and polymerization. Accumulation of the bodied protein in hepatocytes endoplasmic reticulum results in chronic liver disease, cirrhosis and other liver pathologies. A1AT deficiency is a common disorder, however, this diagnosis is established in a small part of the patients. A1AT deficiency is often misdiagnosed as COPD, asthma or сryptogenic liver disease. Usually, due to underestimating the prevalence of the disease and its unspecific symptoms, the diagnosis delay is more than 5 years (on average about 8 years). Nowadays it is possible to treat lung form of A1AT deficiency used the augmentation therapy, that bases on intravenous infusions of pure human A1AT. Also, the active development of new drugs to improve the prognosis in the patients with liver pathology is ongoing. Modern approaches of A1AT deficiency treatment, focused on gene therapy, are becoming a promising direction in the managing of both pulmonary and hepatic pathology with A1AT deficiency.

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