Alpha-1 Antitrypsin Deficiency Liver Disease Research Articles

Liver Characterization of a Cohort of Alpha-1 Antitrypsin Deficiency Patients with and without Lung Disease.

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder characterized by the misfolding and accumulation of the mutant variant of alpha-1 antitrypsin (AAT) within hepatocytes, which limits its access to the circulation and exposes the lungs to protease-mediated tissue damage. This results in progressive liver disease secondary to AAT polymerization and accumulation, and chronic obstructive pulmonary disease (COPD) due to deficient levels of AAT within the lungs. Our goal was to characterize the unique effects of COPD secondary to AATD on liver disease and gene expression. A subcohort of AATD individuals with COPD (n = 33) and AATD individuals without COPD (n = 14) were evaluated in this study from our previously reported cross-sectional cohort. We used immunohistochemistry to assess the AATD liver phenotype, and RNA sequencing to explore liver transcriptomics. We observed a distinct transcriptomic profile in liver tissues from AATD individuals with COPD compared to those without. A total of 339 genes were differentially expressed. Canonical pathways related to fibrosis, extracellular matrix remodeling, collagen deposition, hepatocellular damage, and inflammation were significantly upregulated in the livers of AATD individuals with COPD. Histopathological analysis also revealed higher levels of fibrosis and hepatocellular damage in these individuals. Our data supports a relationship between the development of COPD and liver disease in AATD and introduces genes and pathways that may play a role in AATD liver disease when COPD is present. We believe addressing lung impairment and airway inflammation may be an approach to managing AATD-related liver disease.

Alpha-1 antitrypsin deficiency and Pi*Z allele as important co-factors in the development of liver fibrosis.

Alpha-1 antitrypsin deficiency (AATD) is a codominant autosomal hereditary condition that predisposes patients to the development of lung and/or liver disease, and Pi*Z allele is the most clinically relevant mutation. To evaluate the impact of clinical parameters and AATD phenotypes, particularly the Pi*Z allele, in liver fibrosis. Cross-sectional cohort study including consecutive patients with AATD followed in Pulmonology or Hepatology consultation. Included 69 patients, 49.3% had Pi*MZ phenotype and 10.1% Pi*ZZ. An age ≥ 55 years, age at diagnosis ≥ 41 years and AAT at diagnosis < 77 mg/dL predicted a nonalcoholic fatty liver disease fibrosis score (NFS) not excluding advanced fibrosis [area under the curve (AUC) = 0.840, P < 0.001; AUC = 0.836, P < 0.001; AUC = 0.681, P = 0.025]. An age ≥ 50 years and age at diagnosis ≥ 41 years predicted a fibrosis-4 index of moderate to advanced fibrosis (AUC = 0.831, P < 0.001; AUC = 0.795, P < 0.001). Patients with hypertension, type 2 diabetes mellitus (DM), dyslipidaemia, metabolic syndrome, and regular alcohol consumption were more likely to have a NFS not excluding advanced fibrosis (P < 0.001, P = 0.002, P = 0.008, P < 0.001, P = 0.033). Patients with at least one Pi*Z allele and type 2 DM were 8 times more likely to have liver stiffness measurement ≥ 7.1 kPa (P = 0.040). Risk factors for liver disease in AATD included an age ≥ 50 years, age at diagnosis ≥ 41 years, metabolic risk factors, regular alcohol consumption, at least one Pi*Z allele, and AAT value at diagnosis < 77 mg/dL. We created an algorithm for liver disease screening in AATD patients to use in primary care, selecting those to be referred to Hepatology consultation.

Evaluation of cytosine base editing and adenine base editing as a potential treatment for alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AATD) is a rare autosomal codominant disease caused by mutations within the SERPINA1 gene. The most prevalent variant in patients is PiZ SERPINA1, containing a single G > A transition mutation. PiZ alpha-1 antitrypsin (AAT) is prone to misfolding, leading to the accumulation of toxic aggregates within hepatocytes. In addition, the abnormally low level of AAT secreted into circulation provides insufficient inhibition of neutrophil elastase within the lungs, eventually causing emphysema. Cytosine and adenine base editors enable the programmable conversion of C⋅G to T⋅A and A⋅T to G⋅C base pairs, respectively. In this study, two different base editing approaches were developed: use of a cytosine base editor to install a compensatory mutation (p.Met374Ile) and use of an adenine base editor to mediate the correction of the pathogenic PiZ mutation. After treatment with lipid nanoparticles formulated with base editing reagents, PiZ-transgenic mice exhibited durable editing of SERPINA1 in the liver, increased serum AAT, and improved liver histology. These results indicate that base editing has the potential to address both lung and liver disease in AATD.

The Mechanism of Mitochondrial Injury in Alpha-1 Antitrypsin Deficiency Mediated Liver Disease.

Alpha-1 antitrypsin deficiency (AATD) is caused by a single mutation in the SERPINA1 gene, which culminates in the accumulation of misfolded alpha-1 antitrypsin (ZAAT) within the endoplasmic reticulum (ER) of hepatocytes. AATD is associated with liver disease resulting from hepatocyte injury due to ZAAT-mediated toxic gain-of-function and ER stress. There is evidence of mitochondrial damage in AATD-mediated liver disease; however, the mechanism by which hepatocyte retention of aggregated ZAAT leads to mitochondrial injury is unknown. Previous studies have shown that ER stress is associated with both high concentrations of fatty acids and mitochondrial dysfunction in hepatocytes. Using a human AAT transgenic mouse model and hepatocyte cell lines, we show abnormal mitochondrial morphology and function, and dysregulated lipid metabolism, which are associated with hepatic expression and accumulation of ZAAT. We also describe a novel mechanism of ZAAT-mediated mitochondrial dysfunction. We provide evidence that misfolded ZAAT translocates to the mitochondria for degradation. Furthermore, inhibition of ZAAT expression restores the mitochondrial function in ZAAT-expressing hepatocytes. Altogether, our results show that ZAAT aggregation in hepatocytes leads to mitochondrial dysfunction. Our findings suggest a plausible model for AATD liver injury and the possibility of mechanism-based therapeutic interventions for AATD liver disease.

Shear Wave Elastography and Shear Wave Dispersion Imaging in the Assessment of Liver Disease in Alpha1-Antitrypsin Deficiency.

Liver affection of Alpha1-antitrypsin deficiency (AATD) can lead to cirrhosis and hepatocellular carcinoma (HCC). A noninvasive severity assessment of liver disease in AATD is urgently needed since laboratory parameters may not accurately reflect the extent of liver involvement. Preliminary data exist on two-dimensional shear wave elastography (2D-SWE) being a suitable method for liver fibrosis measurement in AATD. AATD patients without HCC were examined using 2D-SWE, shear wave dispersion imaging (SWD) and transient elastography (TE). Furthermore, liver steatosis was assessed using the controlled attenuation parameter (CAP) and compared to the new method of attenuation imaging (ATI). 29 AATD patients were enrolled, of which 18 had the PiZZ genotype, eight had PiMZ, two had PiSZ and one had a PiZP-Lowell genotype. 2D-SWE (median 1.42 m/S, range 1.14–1.83 m/S) and TE (median 4.8 kPa, range 2.8–24.6 kPa) values displayed a significant correlation (R = 0.475, p < 0.05). 2D-SWE, ATI (median 0.56 dB/cm/MHz, range 0.43–0.96 dB/cm/MHz) and CAP (median 249.5 dB/m, range 156–347 dB/m) values were higher in PiZZ when compared to other AATD genotypes. This study provides evidence that 2D-SWE is a suitable method for the assessment of liver disease in AATD. The newer methods of SWD and ATI require further evaluation in the context of AATD.

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.

THU-407 - Multi-center study of liver disease in alpha1-antitrypsin deficiency: non-invasive evaluation of liver fibrosis in homozygous PiZZ patients

THU-407 - Multi-center study of liver disease in alpha1-antitrypsin deficiency: non-invasive evaluation of liver fibrosis in homozygous PiZZ patients

Antisense oligonucleotide treatment ameliorates alpha-1 antitrypsin–related liver disease in mice

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disease that results from mutations in the alpha-1 antitrypsin (AAT) gene. The mutant AAT protein aggregates and accumulates in the liver leading to AATD liver disease, which is only treatable by liver transplant. The PiZ transgenic mouse strain expresses a human AAT (hAAT) transgene that contains the AATD-associated Glu342Lys mutation. PiZ mice exhibit many AATD symptoms, including AAT protein aggregates, increased hepatocyte death, and liver fibrosis. In the present study, we systemically treated PiZ mice with an antisense oligonucleotide targeted against hAAT (AAT-ASO) and found reductions in circulating levels of AAT and both soluble and aggregated AAT protein in the liver. Furthermore, AAT-ASO administration in these animals stopped liver disease progression after short-term treatment, reversed liver disease after long-term treatment, and prevented liver disease in young animals. Additionally, antisense oligonucleotide treatment markedly decreased liver fibrosis in this mouse model. Administration of AAT-ASO in nonhuman primates led to an approximately 80% reduction in levels of circulating normal AAT, demonstrating potential for this approach in higher species. Antisense oligonucleotides thus represent a promising therapy for AATD liver disease.

History of the First Description of Childhood Liver Disease in AATD

This supplement celebrates the 50th anniversary of Alpha-1 antitrypsin deficiency (AATD). Initially AATD was associated with an inherited form of emphysema. This historical article describes the predisposition of AATD to liver disease. The morphologic findings contributed to a better understanding of low serum levels of A1 AT by the finding of AAT accumulating and stuck in the lumen of the rough endoplasmic reticulum of the hepatocyte. Thus, only low levels of PiZ were secreted for the rest of the human body and the only clinical correction was by liver transplantation.

Hepatobiliary scintigraphy and the string test in the evaluation of neonatal cholestasis.

We evaluated [99mTc]diisopropylphenyl-carbamoylmethylimidodiacetic acid ([99mTc]DISIDA) cholescintigraphy with measurement of duodenal fluid radioactivity collected by the string test in patients with neonatal cholestasis. Twenty-six infants with prolonged jaundice and acholic stools were studied prospectively. Twelve patients had neonatal hepatitis, 12 biliary atresia, and one each Alagille syndrome and alpha 1-antitrypsin deficiency liver disease. All infants except the biliary atresia patients and four of the neonatal hepatitis patients revealed bowel activity on scan 6 h after tracer administration. At 24 h, three of these latter patients with neonatal hepatitis and two of the patients with biliary atresia revealed bowel activity. String radioactive counts for neonatal hepatitis ranged from 99,574 to 967,205 cpm (374,504 +/- 232,210 cpm; mean +/- SD) and for biliary atresia from 8,342 to 370,346 cpm (117,149 +/- 98,698 cpm; mean +/- SD). While neither test alone was capable of correctly differentiating among all patients, those patients with biliary atresia had either a negative hepatobiliary scan at 24 h or string radioactive count below 197,007 cpm. Disparity between the hepatobiliary scan and the string radioactive counts mandates further diagnostic investigation. These data suggest that simultaneous administration of the string test with hepatobiliary scintigraphy is advantageous in the evaluation of infants with cholestatic jaundice.

Liver disease in adults with alpha-1 -antitrypsin deficiency.

Examination of hepatic tissue obtained at autopsy (13 cases) and by biopsy (one case) from patients with homozygous alpha1-antitrypsin deficiency showed that the hepatocytes contained periodic-acid-Schiff-positive globular material similar to that seen in infantile cirrhosis with alpha1-antitrypsin deficiency. Five of the adult patients had cirrhosis, and three fibrosis of the liver; of these eight, all over 50 years of age, three also had hepatomas. Twelve of the 13 autopsy cases had either bullous or panacinar emphysema. The findings suggest that in alpha1-antitrypsin deficiency liver disease and emphysema are linked to the same genetic defect.