Clinical and histologic features of adults with alpha-1 antitrypsin deficiency in a non-cirrhotic cohort

Quantification of circulating alpha-1-antitrypsin polymers associated with different SERPINA1 genotypes

OBJECTIVES

Alpha-1-antitrypsin deficiency is a genetic disorder caused by mutations in the SERPINA1 gene encoding alpha-1-antitrypsin (AAT), the major serine protease inhibitor in plasma. Reduced AAT levels are associated with elevated risk of developing emphysema mainly due to uncontrolled activity of neutrophil elastase in the lungs. The prevalent Z-AAT mutant and many rare pathogenic AAT variants also predispose to liver disease due to their accumulation as polymeric chains in hepatocytes. Part of these polymers are secreted into the bloodstream and could represent biomarkers of intra-hepatic accumulation. Moreover, being inactive, they further lower lung protection against proteases. Aim of our study is to accurately quantify the percentage of circulating polymers (CP) in a cohort of subjects with different SERPINA1 genotypes.

METHODS

CP concentration was measured in plasma or Dried Blood Spot (DBS) by a sensitive sandwich ELISA based on capture by the polymer-specific 2C1 monoclonal antibody.

RESULTS

CP were significantly elevated in patients with the prevalent PI*SZ and PI*ZZ genotypes, with considerable intra-genotype variability. Notably, higher percentage of polymers was observed in association with elevated C-reactive protein. CP levels were also increased in carriers of the Mmalton variant, and of Mprocida, I, Plowell and Mherleen in heterozygosity with Z-AAT.

CONCLUSIONS

These findings highlight the importance of implementing CP quantification in a clinical laboratory. Indeed, the variable amount of CP in patients with the same genotype may correlate with the variable severity of the associated lung and liver diseases. Moreover, CP can reveal the polymerogenic potential of newly discovered ultrarare AAT variants.

Fibrosis, biomarkers and liver biopsy in AAT deficiency and relation to liver Z protein polymer accumulation

BACKGROUND AND AIMS

The course of adults with ZZ alpha-1-antitrypsin deficiency (AATD) liver disease is unpredictable. The utility of markers, including liver biopsy, is undefined.

METHODS

A prospective cohort, including protocol liver biopsies, was enrolled to address these questions.

RESULTS

We enrolled 96 homozygous ZZ AATD adults prospectively at three US sites with standardized clinical evaluations, and protocol liver biopsies. Fibrosis was scored using Ishak (stages 0-6). Also, 51% of the 96 subjects had Ishak score >1 fibrosis (49% Ishak 0-1, 36% Ishak 2-3 and 15% ≥4). Elevated aspartate aminotransferase (AST) more than alanine aminotransferase (ALT), high body mass index (BMI), obesity, AST platelet ratio index and elevated serum Z alpha 1 antitrypsin (AAT) polymer levels were associated with increased fibrosis. Steatosis did not correlate to fibrosis. Increased fibrosis was associated with increased mutant Z polymer globular inclusions (p = .002) and increased diffuse cytoplasmic Z polymer on biopsy (p = .0029) in a direct relationship. Increased globule Z polymer was associated with increased serum AST (p = .007) and increased periportal inflammation on histopathology (p = .004), but there was no relationship of Z polymer hepatocellular accumulation with ALT, gamma glutamine transferase, inflammation in other parts of the lobule, necrosis or steatosis. Serum Z polymer levels were directly correlated to hepatic Z protein polymer content. Lung function, smoking and alcohol consumption patterns were not associated with fibrosis.

CONCLUSION

In AATD high BMI, obesity and elevated AST are associated with increased fibrosis. Liver biopsy features are correlated to some serum tests. Serum Z AAT polymer levels could be a future biomarker to detect fibrosis early and is directly correlated to liver Z content.

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

BACKGROUND

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.

AIM

To evaluate the impact of clinical parameters and AATD phenotypes, particularly the Pi*Z allele, in liver fibrosis.

METHODS

Cross-sectional cohort study including consecutive patients with AATD followed in Pulmonology or Hepatology consultation.

RESULTS

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).

CONCLUSION

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.

EASL Clinical Practice Guidelines on genetic cholestatic liver diseases

Genetic cholestatic liver diseases are caused by (often rare) mutations in a multitude of different genes. While these diseases differ in pathobiology, clinical presentation and prognosis, they do have several commonalities due to their cholestatic nature. These Clinical Practice Guidelines (CPGs) offer a general approach to genetic testing and management of cholestatic pruritus, while exploring diagnostic and treatment approaches for a subset of genetic cholestatic liver diseases in depth. An expert panel appointed by the European Association for the Study of the Liver has created recommendations regarding diagnosis and treatment, based on the best evidence currently available in the fields of paediatric and adult hepatology, as well as genetics. The management of these diseases generally takes place in a tertiary referral centre, in order to provide up-to-date approaches and expertise. These CPGs are intended to support hepatologists (for paediatric and adult patients), residents and other healthcare professionals involved in the management of these patients with concrete recommendations based on currently available evidence or, if not available, on expert opinion.

Alcohol consumption and liver phenotype of individuals with alpha-1 antitrypsin deficiency

BACKGROUND AND AIMS

Alpha-1 antitrypsin deficiency is an inherited disorder caused by alpha-1 antitrypsin (AAT) mutations. We analysed the association between alcohol intake and liver-related parameters in individuals with the heterozygous/homozygous Pi*Z AAT variant (Pi*MZ/Pi*ZZ genotype) found in the United Kingdom Biobank and the European Alpha1 liver consortium.

METHODS

Reported alcohol consumption was evaluated in two cohorts: (i) the community-based United Kingdom Biobank (17 145 Pi*MZ, 141 Pi*ZZ subjects, and 425 002 non-carriers [Pi*MM]); and (ii) the European Alpha1 liver consortium (561 Pi*ZZ individuals). Cohort (ii) included measurements of carbohydrate-deficient transferrin (CDT).

RESULTS

In both cohorts, no/low alcohol intake was reported by >80% of individuals, while harmful consumption was rare (~1%). Among Pi*MM and Pi*MZ individuals from cohort (i), moderate alcohol consumption resulted in a <30% increased rate of elevated transaminases and ~50% increase in elevated gamma-glutamyl transferase values, while harmful alcohol intake led to an at least twofold increase in the abnormal levels. In Pi*ZZ individuals from both cohorts, moderate alcohol consumption had no marked impact on serum transaminase levels. Among Pi*ZZ subjects from cohort (ii) who reported no/low alcohol consumption, those with increased CDT levels more often had signs of advanced liver disease.

CONCLUSIONS

Pi*MZ/Pi*ZZ genotype does not seem to markedly aggravate the hepatic toxicity of moderate alcohol consumption. CDT values might be helpful to detect alcohol consumption in those with advanced fibrosis. More data are needed to evaluate the impact of harmful alcohol consumption.

Association of circulating Z-polymer with adverse clinical outcomes and liver fibrosis in adults with alpha-1 antitrypsin deficiency

BACKGROUND

Circulating polymerized mutant Z-alpha-1 antitrypsin (Z-polymer) constitutes a characteristic feature in alpha-1 antitrypsin deficiency (AATD), but there is limited knowledge about its association with adverse clinical outcomes and liver fibrosis. We explored this association using data from a large cohort of adults with AATD.

METHODS

A total of 836 (431 PiZZ, 405 PiMZ) adults with AATD and 312 controls (PiMM) from the European Alpha-1 Liver Cohort (2015-2020) were included. Time-to-event analyses were conducted for adults with the PiZZ genotype followed for adverse clinical outcomes (earliest occurrence of liver-related hospitalization, liver transplant or all-cause mortality). Cox proportional hazard models were used to describe the association between binary circulating Z-polymer levels and adverse clinical outcomes. Correlations between baseline circulating Z-polymer levels and baseline liver fibrosis (liver stiffness measurement [LSM] determined by transient elastography [FibroScan®]) were evaluated. The analyses were stratified by augmentation therapy status.

RESULTS

Of 324 adults with the PiZZ genotype and longitudinal follow-up data, 28 reported adverse clinical outcomes. Higher baseline circulating Z-polymer levels were associated with an increased risk of adverse clinical outcomes in both crude (hazard ratio [95% confidence interval, CI], 2.88 [1.21, 6.87]) and age-adjusted (1.96 [0.78, 4.94]) analyses. In adults with the PiZZ genotype, circulating Z-polymer levels were weakly positively correlated with baseline LSM (Spearman's rho [95% CI]: 0.21 [0.11, 0.31]). Similar results were observed after stratification by augmentation therapy status.

CONCLUSIONS

In adults with the PiZZ genotype, higher circulating Z-polymer levels were associated with a shorter time to adverse clinical outcome, and positively correlated with baseline LSM. Circulating Z-polymer levels may be a prognostic biomarker of clinically relevant disease in AATD.

Fazirsiran for Adults With Alpha-1 Antitrypsin Deficiency Liver Disease: A Phase 2 Placebo Controlled Trial (SEQUOIA)

BACKGROUND & AIMS

Homozygous ZZ alpha-1 antitrypsin (AAT) deficiency produces mutant AAT (Z-AAT) proteins in hepatocytes, leading to progressive liver fibrosis. We evaluated the safety and efficacy of an investigational RNA interference therapeutic, fazirsiran, that degrades Z-AAT messenger RNA, reducing deleterious protein synthesis.

METHODS

This ongoing, phase 2 study randomized 40 patients to subcutaneous placebo or fazirsiran 25, 100, or 200 mg. The primary endpoint was percent change in serum Z-AAT concentration from baseline to week 16. Patients with fibrosis on baseline liver biopsy received treatment on day 1, at week 4, and then every 12 weeks and had a second liver biopsy at or after weeks 48, 72, or 96. Patients without fibrosis received 2 doses on day 1 and at week 4.

RESULTS

At week 16, least-squares mean percent declines in serum Z-AAT concentration were -61%, -83%, and -94% with fazirsiran 25, 100, and 200 mg, respectively, vs placebo (all P < .0001). Efficacy was sustained through week 52. At postdose liver biopsy, fazirsiran reduced median liver Z-AAT concentration by 93% compared with an increase of 26% with placebo. All fazirsiran-treated patients had histologic reduction from baseline in hepatic globule burden. Portal inflammation improved in 5 of 12 and 0 of 8 patients with a baseline score of >0 in the fazirsiran and placebo groups, respectively. Histologic meta-analysis of histologic data in viral hepatitis score improved by >1 point in 7 of 14 and 3 of 8 patients with fibrosis of >F0 at baseline in the fazirsiran and placebo groups, respectively. No adverse events led to discontinuation, and pulmonary function tests remained stable.

CONCLUSIONS

Fazirsiran reduced serum and liver concentrations of Z-AAT in a dose-dependent manner and reduced hepatic globule burden. (ClinicalTrials.gov, Number NCT03945292).

Review article: New developments in biomarkers and clinical drug development in alpha-1 antitrypsin deficiency-related liver disease

BACKGROUND

Alpha-1 antitrypsin liver disease (AATLD) occurs in a subset of patients with alpha-1 antitrypsin deficiency. Risk factors for disease progression and specific pathophysiologic features are not well known and validated non-invasive assessments for disease severity are lacking. Currently, there are no approved treatments for AATLD.

AIMS

To outline existing understanding of AATLD and to identify knowledge gaps critical to improving clinical trial design and development of new treatments.

METHODS

This report was developed following a multi-stakeholder forum organised by the Alpha-1 Antitrypsin Deficiency Related Liver Disease Expert Panel in which experts presented an overview of the available literature on this topic.

RESULTS

AATLD results from a 'gain of toxic function' and primarily manifests in those with the homozygous Pi*ZZ genotype. Accumulation of misfolded 'Z' AAT protein in liver cells triggers intracellular hepatocyte injury which may ultimately lead to hepatic fibrosis. Male gender, age over 50 years, persistently elevated liver tests, concomitant hepatitis B or C virus infection, and metabolic syndrome, including obesity and type 2 diabetes mellitus, are known risk factors for adult AATLD. While the gold standard for assessing AATLD disease activity is liver histology, less invasive measures with low intra- and inter-observer variability are needed. Measurement of liver stiffness shows promise; validated thresholds for staging AATLD are in development. Such advances will help patients by enabling risk stratification and personalised surveillance, along with streamlining the development process for novel therapies.

CONCLUSIONS

This inaugural forum generated a list of recommendations to address unmet needs in the field of AATLD.

Impact of PNPLA3 I148M on alpha-1 antitrypsin deficiency-dependent liver disease progression

BACKGROUND AND AIMS

Genetic risk factors are major determinants of chronic liver disease (CLD) progression. Patatin-like phospholipase domain-containing protein 3 (PNPLA3) I148M polymorphism and alpha-1 antitrypsin (AAT) E342K variant, termed PiZ, are major modifiers of metabolic CLD. Both variants are known to affect metabolic CLD through increased endoplasmic reticulum stress, but their combined effect on CLD progression remains largely unknown. Here, we aimed to test our working hypothesis that their combined incidence triggers CLD disease progression.

APPROACH AND RESULTS

We showed that patients with PiZZ/PNPLA3 I148M from the European alpha-1-antitrypsin deficiency (AATD) liver consortium and the UK Biobank had a trend towards higher liver enzymes, but no increased liver fat accumulation was evident between subgroups. After generating transgenic mice that overexpress the PiZ variant and simultaneously harbor the PNPLA3 I148M knockin (designated as PiZ/PNPLA3 I148M ), we observed that animals with PiZ and PiZ/PNPLA3 I148M showed increased liver enzymes compared to controls during aging. However, no significant difference between PiZ and PiZ/PNPLA3 I148M groups was observed, with no increased liver fat accumulation over time. To further study the impact on CLD progression, a Western-styled diet was administered, which resulted in increased fat accumulation and fibrosis in PiZ and PiZ/PNPLA3 I148M livers compared to controls, but the additional presence of PNPLA3 I148M had no impact on liver phenotype. Notably, the PiZ variant protected PNPLA3 I148M mice from liver damage and obesity after Western-styled diet feeding.

CONCLUSION

Our results demonstrate that the PNPLA3 polymorphism in the absence of additional metabolic risk factors is insufficient to drive the development of advanced liver disease in severe AATD.

UK guideline on the transition and management of childhood liver diseases in adulthood

INTRODUCTION

Improved outcomes of liver disease in childhood and young adulthood have resulted in an increasing number of young adults (YA) entering adult liver services. The adult hepatologist therefore requires a working knowledge in diseases that arise almost exclusively in children and their complications in adulthood.

AIMS

To provide adult hepatologists with succinct guidelines on aspects of transitional care in YA relevant to key disease aetiologies encountered in clinical practice.

METHODS

A systematic literature search was undertaken using the Pubmed, Medline, Web of Knowledge and Cochrane database from 1980 to 2023. MeSH search terms relating to liver diseases ('cholestatic liver diseases', 'biliary atresia', 'metabolic', 'paediatric liver diseases', 'autoimmune liver diseases'), transition to adult care ('transition services', 'young adult services') and adolescent care were used. The quality of evidence and the grading of recommendations were appraised using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

RESULTS

These guidelines deal with the transition of YA and address key aetiologies for the adult hepatologist under the following headings: (1) Models and provision of care; (2) screening and management of mental health disorders; (3) aetiologies; (4) timing and role of liver transplantation; and (5) sexual health and fertility.

CONCLUSIONS

These are the first nationally developed guidelines on the transition and management of childhood liver diseases in adulthood. They provide a framework upon which to base clinical care, which we envisage will lead to improved outcomes for YA with chronic liver disease.

Sirtuin3 promotes the degradation of hepatic Z alpha-1 antitrypsin through lipophagy

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is a genetic disease caused by misfolding and accumulation of mutant alpha-1 antitrypsin (ZAAT) in the endoplasmic reticulum of hepatocytes. Hepatic ZAAT aggregates acquire a toxic gain-of-function that impacts the endoplasmic reticulum which is theorized to cause liver disease in individuals with AATD who present asymptomatic until late-stage cirrhosis. Currently, there is no treatment for AATD-mediated liver disease except liver transplantation. In our study of mitochondrial RNA, we identified that Sirtuin3 (SIRT3) plays a role in the hepatic phenotype of AATD.

METHODS

Utilizing RNA and protein analysis in an in vitro AATD model, we investigated the role of SIRT3 in the pathophysiology of AATD-mediated liver disease while also characterizing our novel, transgenic AATD mouse model.

RESULTS

We show lower expression of SIRT3 in ZAAT-expressing hepatocytes. In contrast, the overexpression of SIRT3 increases hepatic ZAAT degradation. ZAAT degradation mediated by SIRT3 appeared independent of proteasomal degradation and regular autophagy pathways. We observed that ZAAT-expressing hepatocytes have aberrant accumulation of lipid droplets, with ZAAT polymers localizing on the lipid droplet surface in a direct interaction with Perilipin2, which coats intracellular lipid droplets. SIRT3 overexpression also induced the degradation of lipid droplets in ZAAT-expressing hepatocytes. We observed that SIRT3 overexpression induces lipophagy by enhancing the interaction of Perilipin2 with HSC70. ZAAT polymers then degrade as a consequence of the mobilization of lipids through this process.

CONCLUSIONS

In this context, SIRT3 activation may eliminate the hepatic toxic gain-of-function associated with the polymerization of ZAAT, providing a rationale for a potential novel therapeutic approach to the treatment of AATD-mediated liver disease.

Alpha-1 Antitrypsin Augmentation and the Liver Phenotype of Adults With Alpha-1 Antitrypsin Deficiency (Genotype Pi∗ZZ)

BACKGROUND & AIMS

α1-Antitrypsin (AAT) is a major protease inhibitor produced by hepatocytes. The most relevant AAT mutation giving rise to AAT deficiency (AATD), the 'Pi∗Z' variant, causes harmful AAT protein accumulation in the liver, shortage of AAT in the systemic circulation, and thereby predisposes to liver and lung injury. Although intravenous AAT augmentation constitutes an established treatment of AATD-associated lung disease, its impact on the liver is unknown.

METHODS

Liver-related parameters were assessed in a multinational cohort of 760 adults with severe AATD (Pi∗ZZ genotype) and available liver phenotyping, of whom 344 received augmentation therapy and 416 did not. Liver fibrosis was evaluated noninvasively via the serum test AST-to-platelet ratio index and via transient elastography-based liver stiffness measurement. Histologic parameters were compared in 15 Pi∗ZZ adults with and 35 without augmentation.

RESULTS

Compared with nonaugmented subjects, augmented Pi∗ZZ individuals displayed lower serum liver enzyme levels (AST 71% vs 75% upper limit of normal, P < .001; bilirubin 49% vs 58% upper limit of normal, P = .019) and lower surrogate markers of fibrosis (AST-to-platelet ratio index 0.34 vs 0.38, P < .001; liver stiffness measurement 6.5 vs 7.2 kPa, P = .005). Among biopsied participants, augmented individuals had less pronounced liver fibrosis and less inflammatory foci but no differences in AAT accumulation were noted.

CONCLUSIONS

The first evaluation of AAT augmentation on the Pi∗ZZ-related liver disease indicates liver safety of a widely used treatment for AATD-associated lung disease. Prospective studies are needed to confirm the beneficial effects and to demonstrate the potential efficacy of exogenous AAT in patients with Pi∗ZZ-associated liver disease.

Liver disease progression in patients with alpha-1 antitrypsin deficiency and protease inhibitor ZZ genotype with or without lung disease

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is caused by mutations in SERPINA1, which encodes alpha-1 antitrypsin, a protease inhibitor (Pi). Individuals with AATD and the homozygous Pi*ZZ genotype have variable risk of progressive liver disease but the influence of comorbid lung disease is poorly understood.

AIMS

To characterise patients with AATD Pi*ZZ and liver disease (AATD-LD-Pi*ZZ) with or without lung disease and describe liver disease-related clinical events longitudinally.

METHODS

This was an observational cohort study of patients in the Mayo Clinic Healthcare System (January 2000-September 2021). Patients were identified using diagnosis codes and natural language processing. Fibrosis stage (F0-F4) was assessed using a hierarchical approach at baseline (90 days before or after the index date) and follow-up. Clinical events associated with liver disease progression were assessed.

RESULTS

AATD-LD-Pi*ZZ patients with lung disease had a longer median time from AATD diagnosis to liver disease diagnosis versus those without lung disease (2.2 vs. 0.2 years, respectively). Compared to those without lung disease, patients with lung disease had a longer time to liver disease-related clinical events (8.5 years and not reached, respectively). AATD-LD-Pi*ZZ patients without lung disease were more likely to undergo liver transplantation compared with those with lung disease.

CONCLUSION

In patients with AATD and lung disease, there is a delay in the diagnosis of comorbid liver disease. Our findings suggest that liver disease may progress more rapidly in patients without comorbid lung disease.

Future Perspectives in the Diagnosis and Treatment of Liver Disease Associated with Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin deficiency (AATD) is one of the most common genetic diseases and is caused by mutations in the SERPINA1 gene. The homozygous Pi*Z variant is responsible for the majority of the classic severe form of alpha-1 antitrypsin deficiency, which is characterized by markedly decreased levels of serum alpha-1 antitrypsin (AAT) with a strong predisposition to lung and liver disease. The diagnosis and early treatment of AATD-associated liver disease are challenges in clinical practice. In this review, the authors aim to summarize the current evidence of the non-invasive methods in the assessment of liver fibrosis, as well as to elucidate the main therapeutic strategies under investigation that may emerge in the near future.

Alpha1-antitrypsin deficiency: An updated review

Alpha1-antitrypsin deficiency (AATD) is a rare autosomal recessive disease associated with the homozygous Z variant of the SERPINA1 gene. Clinical expression of AATD, reported 60 years ago associate a severe deficiency, pulmonary emphysema and/or liver fibrosis. Pulmonary emphysema is due to the severe alpha1-antitrypsin deficiency of the ZZ homozygous status and is favored by smoking. Liver fibrosis is due to the ZZ homozygous status and is favored by obesity and excessive chronic alcohol intake, with a risk of liver cancer. Diagnosis is based on serum level and either isoelectric focusing determination of the biochemical phenotype or PCR detection of some variants. SERPINA1 gene sequencing is necessary in case of discrepancies between the results of these tests. No treatment is available for the liver disease in AATD. Although no specific trial has been performed, COPD in AATD should be treated as per COPD recommendations. Based on a randomized clinical trial, augmentation therapy is indicated in non-smoking adults less than 70 years of age with emphysema at chest CT, confirmed homozygous AATD, and FEV1 between 35% and 70% of predicted. In contrast Z heterozygosis (MZ or SZ) brings a risk of lung or liver disease only in association with further risk factors. Early detection, in all patients with COPD and chronic liver disease, is critical for the correct information of Z variant carriers. News ways of correcting the liver production of alpha1-antitrypsin will modify the care of AATD patients.

Initial alpha-1 antitrypsin screening in Turkish patients with chronic obstructive pulmonary disease

BACKGROUND

Alpha-1 antitrypsin (AAT) deficiency is associated with several types of pathology, and the reported effects of mutations in the ATT-encoding gene vary worldwide. No Turkish study has yet appeared. We thus explored the AAT status of Turkish patients with chronic obstructive pulmonary disease (COPD).

METHODS

This prospective cross-sectional study included outpatients and inpatients treated from June 2021 to June 2022. Serum AAT levels were checked, and dry blood samples were subjected to genetic analysis.

RESULTS

: Genetic mutations were found in 21 (3.52%) of 596 patients with prior and new COPD diagnoses treated in our pneumonology outpatient department. The mean serum AAT level was 114.80 mg/dL (minimum 19, maximum 209; standard deviation 27.86 mg/dL). The most frequent mutation was M/Plowell (23.8%, n = 5), followed by M/S (23.8%, n = 5), M/I (19%, n = 4), M/Malton (14.3%, n = 3), Z/Z (9.5%, n = 2), M/Z (4.8%, n = 1), and Kayseri/Kayseri (4.8%, n = 1). Thoracic computed tomography revealed that 85.7% (n = 18) of all patients had emphysema, 28.5% (n = 6) had bronchiectasis, and 28.5% (n = 6) had mass lesions. Of the emphysema patients, 55% (n = 10) had only upper lobe emphysema, and 83.3% (n = 15) had emphysema in additional areas, but statistical significance was lacking (p > 0.05).

DISCUSSION

In patients with emphysema and normal serum AAT levels, genetic analyses may reveal relevant heterozygous mutations, which are commonly ignored. Most clinicians focus on lower lobe emphysema. Evaluations of such patients might reveal AAT mutations that are presently overlooked because they are not considered to influence COPD status.

Pediatric and Adult Liver Disease in Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin deficiency (AATD) arises due to inherited variants in SERPINA1, the AAT gene that impairs the production or secretion of this hepatocellular protein and leads to a gain-of-function liver proteotoxicity. Homozygous Pi*Z pathogenic variant (Pi*ZZ genotype) is the leading cause of severe AATD. It manifests in 2 to 10% of carriers as neonatal cholestasis and 20 to 35% of adults as significant liver fibrosis. Both children and adults may develop an end-stage liver disease requiring liver transplantation. Heterozygous Pi*Z pathogenic variant (Pi*MZ genotype) constitutes an established disease modifier. Our review summarizes the natural history and management of subjects with both pediatric and adult AATD-associated liver disease. Current findings from a phase 2 clinical trial indicate that RNA silencing may constitute a viable therapeutic approach for adult AATD. In conclusion, AATD is an increasingly appreciated pediatric and adult liver disorder that is becoming an attractive target for modern pharmacologic strategies.

Meta-analysis: Prevalence of significant or advanced fibrosis in adults with alpha-1-antitrypsin deficiency

BACKGROUND

The prevalence of liver fibrosis detected by non-invasive imaging in alpha-1-antitrypsin (AAT) deficiency has not been systematically assessed.

AIMS

We conducted a systematic review and meta-analysis to determine the prevalence of significant fibrosis and advanced fibrosis in AAT deficiency based on non-invasive imaging.

METHODS

Medline and Embase electronic databases were searched for studies from inception to 13 November 2022 that provided data for the prevalence of fibrosis in adults with AAT deficiency. A generalised linear mixed model with Clopper-Pearson intervals was used to pool single-arm outcomes.

RESULTS

Of the 214 records identified, 8 studies were included. Five studies assessed fibrosis using vibration-controlled transient elastography. The prevalence of significant fibrosis (defined as ≥7.1 kPA) in Z homozygosity, Z heterozygosity and non-carrier status was 22.10% (five studies, 95% CI: 17.07-28.12), 9.24% (three studies, 95% CI: 4.68-17.45) and 5.38% (one study, 95% CI: 3.27-8.73), respectively, p < 0.0001, and the prevalence of advanced fibrosis (defined as ≥9.5 kPa) was 8.13% (five studies, 95% CI: 4.60-13.96), 2.96% (three studies, 95% CI: 1.49-5.81) and 1.08% (one study, 95% CI: 0.35-3.28), respectively, p = 0.003. There were limited data regarding the use of magnetic resonance elastography or acoustic radiation force impulse to assess for fibrosis.

CONCLUSION

More than one in five adult individuals with AAT deficiency and Z homozygosity harbour significant fibrosis, and nearly 1 in 10 harbours advanced fibrosis. The risk of fibrosis increases incrementally with the frequency of Pi*Z mutations.

RNAi therapeutics for diseases involving protein aggregation: fazirsiran for alpha-1 antitrypsin deficiency-associated liver disease

INTRODUCTION

Therapeutic agents that prevent protein misfolding or promote protein clearance are being studied to treat proteotoxic diseases. Among them, alpha-1 antitrypsin deficiency (AATD) is caused by mutations in the alpha-1 antitrypsin (SERPINA1) gene. Fazirsiran is a small interfering RNA (siRNA) that is intended to address the underlying cause of liver disease associated with AATD through the RNA interference (RNAi) mechanism.

AREAS COVERED

This article describes the role of misfolded proteins and protein aggregates in disease and options for therapeutic approaches. The RNAi mechanism is discussed, along with how the siRNA therapeutic fazirsiran for the treatment of AATD was developed. We also describe the implications of siRNA therapeutics in extrahepatic diseases.

EXPERT OPINION

Using RNAi as a therapeutic approach is well suited to treat disease in conditions where an excess of a protein or the effect of an abnormal mutated protein causes disease. The results observed for the first few siRNA therapeutics that were approved or are in development provide an important promise for the development of future drugs that can address such conditions in a specific and targeted way. Current developments should enable the use of RNAi therapeutics outside the liver, where there are many more possible diseases to address.

Cleaning up alpha-1 antitrypsin deficiency related liver disease

PURPOSE OF REVIEW

Alpha-1 antitrypsin deficiency (AATD) is one of the most common genetic disorders arising due to mutations in alpha-1 antitrypsin (AAT) gene affecting primarily the lung and the liver. This review summarizes the pathophysiology and clinical manifestation of different AATD genotypes and discusses the recent therapeutic developments. The focus is on the severe, rare homozygous Pi∗ZZ and the common heterozygous Pi∗MZ genotype.

RECENT FINDINGS

Pi∗ZZ individuals harbor an up to 20 times higher risk of liver fibrosis and cirrhosis than noncarriers and liver transplantation is currently the only available therapeutic option. AATD constitutes a proteotoxic disorder arising from hepatic AAT accumulation and the currently most promising data come from a phase 2, open-label trial of fazirsiran, a hepatocyte-targeted siRNA. Pi∗MZ subjects display an increased risk of advanced liver disease and at the latter stage, a faster deterioration than individuals without AAT mutation.

SUMMARY

Although the fazirsiran data offer a glimpse of hope to AATD patients, a consensus on appropriate study endpoint, a careful patient selection as well as monitoring of long-term safety will be essential for an approval.

Alpha-1 antitrypsin deficiency: current therapy and emerging targets

INTRODUCTION

Alpha1 antitrypsin deficiency (AATD), a common hereditary disorder affecting mainly lungs, liver and skin has been the focus of some of the most exciting therapeutic approaches in medicine in the past 5 years. In this review, we discuss the therapies presently available for the different manifestations of AATD and new therapies in the pipeline.

AREAS COVERED

We review therapeutic options for the individual lung, liver and skin manifestations of AATD along with approaches which aim to treat all three. Along with this renewed interest in treating AATD come challenges. How is AAT best delivered to the lung? What is the desired level of AAT in the circulation and lungs which therapeutics should aim to provide? Will treating the liver disease increase the potential for lung disease? Are there treatments to target the underlying genetic defect with the potential to prevent all aspects of AATDrelated disease?

EXPERT OPINION

With a relatively small population able to participate in clinical studies, increased awareness and diagnosis of AATD is urgently needed. Better, more sensitive clinical parameters will assist in the generation of acceptable and robust evidence of therapeutic effect for current and emerging treatments.

Expression of the Z Variant of α1-Antitrypsin Suppresses Hepatic Cholesterol Biosynthesis in Transgenic Zebrafish

Individuals homozygous for the Pi*Z allele of SERPINA1 (ZAAT) are susceptible to lung disease due to insufficient α1-antitrypsin secretion into the circulation and may develop liver disease due to compromised protein folding that leads to inclusion body formation in the endoplasmic reticulum (ER) of hepatocytes. Transgenic zebrafish expressing human ZAAT show no signs of hepatic accumulation despite displaying serum insufficiency, suggesting the defect in ZAAT secretion occurs independently of its tendency to form inclusion bodies. In this study, proteomic, transcriptomic, and biochemical analysis provided evidence of suppressed Srebp2-mediated cholesterol biosynthesis in the liver of ZAAT-expressing zebrafish. To investigate the basis for this perturbation, CRISPR/Cas9 gene editing was used to manipulate ER protein quality control factors. Mutation of erlec1 resulted in a further suppression in the cholesterol biosynthesis pathway, confirming a role for this ER lectin in targeting misfolded ZAAT for ER-associated degradation (ERAD). Mutation of the two ER mannosidase homologs enhanced ZAAT secretion without inducing hepatic accumulation. These insights into hepatic ZAAT processing suggest potential therapeutic targets to improve secretion and alleviate serum insufficiency in this form of the α1-antitrypsin disease.

Capturing the conversion of the pathogenic alpha-1-antitrypsin fold by ATF6 enhanced proteostasis

Genetic variation in alpha-1 antitrypsin (AAT) causes AAT deficiency (AATD) through liver aggregation-associated gain-of-toxic pathology and/or insufficient AAT activity in the lung manifesting as chronic obstructive pulmonary disease (COPD). Here, we utilize 71 AATD-associated variants as input through Gaussian process (GP)-based machine learning to study the correction of AAT folding and function at a residue-by-residue level by pharmacological activation of the ATF6 arm of the unfolded protein response (UPR). We show that ATF6 activators increase AAT neutrophil elastase (NE) inhibitory activity, while reducing polymer accumulation for the majority of AATD variants, including the prominent Z variant. GP-based profiling of the residue-by-residue response to ATF6 activators captures an unexpected role of the "gate" area in managing AAT-specific activity. Our work establishes a new spatial covariant (SCV) understanding of the convertible state of the protein fold in response to genetic perturbation and active environmental management by proteostasis enhancement for precision medicine.

Wilson Disease and Alpha1-Antitrypsin Deficiency: A Review of Non-Invasive Diagnostic Tests

Wilson disease and alpha1-antitrypsin deficiency are two rare genetic diseases that may impact predominantly the liver and/or the brain, and the liver and/or the lung, respectively. The early diagnosis of these diseases is important in order to initiate a specific treatment, when available, ideally before irreversible organ damage, but also to initiate family screening. This review focuses on the non-invasive diagnostic tests available for clinicians in both diseases. These tests are crucial at diagnosis to reduce the potential diagnostic delay and assess organ involvement. They also play a pivotal role during follow-up to monitor disease progression and evaluate treatment efficacy of current or emerging therapies.

Association of Alpha-1 Antitrypsin Pi*Z Allele Frequency and Progressive Liver Fibrosis in Two Chronic Hepatitis C Cohorts

(1) Background: The inherited alpha-1 antitrypsin (A1AT) deficiency variant 'Pi*Z' emerged as a genetic modifier of chronic liver disease. Controversial data exist on the relevance of heterozygous Pi*Z carriage ('Pi*MZ' genotype) as an additional risk factor in patients with chronic viral hepatitis C to develop progressive liver fibrosis. (2) Methods: Two prospectively recruited cohorts totaling 572 patients with therapy-naïve chronic viral hepatitis C (HCV) were analyzed. The Frankfurt cohort included 337 patients and a second cohort from Leipzig included 235 patients. The stage of liver fibrosis was assessed by liver biopsy, AST-to-platelet ratio index (APRI) score and Fibrosis-4 (FIB-4) score (Frankfurt) as well as liver stiffness measurement (LSM) via transient elastography (Leipzig). All patients were genotyped for the Pi*Z variant (rs28929474) of the SERPINA1 gene. (3) Results: In the Frankfurt cohort, 16/337 (4.7%) patients carried the heterozygous Pi*Z allele while 10/235 (4.3%) in the Leipzig cohort were Pi*Z carriers. In both cohorts, there was no higher proportion of Pi*Z heterozygosity in patients with cirrhosis compared to patients without cirrhosis or patients with cirrhosis vs. no liver fibrosis. Accordingly, Pi*Z frequency was not different in histological or serological stages of liver fibrosis (F0-F4) and showed no clear association with LSM. (4) Conclusions: Evaluation in two representative HCV cohorts does not indicate Pi*Z heterozygosity as a clinically relevant disease modifier in chronic HCV infection. However, validation in even larger cohorts with longitudinal follow-up is warranted.

Characterization of hepatic inflammatory changes in a C57BL/6J mouse model of alpha1-antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AATD) is a genetic disease caused by a hepatic accumulation of mutant alpha-1 antitrypsin (ZAAT). Individuals with AATD are prone to develop a chronic liver disease that remains undiagnosed until late stage of the disease. Here, we sought to characterize the liver pathophysiology of a human transgenic mouse model for AATD with a manifestation of liver disease compared with normal transgenic mice model. Male and female transgenic mice for normal (Pi*M) and mutant variant (Pi*Z) human alpha-1 antitrypsin at 3 and 6 mo of age were subjected to this study. The progression of hepatic ZAAT accumulation, hepatocyte injury, steatosis, liver inflammation, and fibrotic features were monitored by performing an in vivo study. We have also performed a Next-Gene transcriptomic analysis of the transgenic mice liver tissue 16 h after lipopolysaccharide (LPS) administration to delineate liver inflammatory response in Pi*Z mice as compared with Pi*M. Our results show hepatic ZAAT accumulation, followed by hepatocyte ballooning and liver steatosis developed at 3 mo in Pi*Z mice compared with the mice carrying normal variant of human alpha-1 antitrypsin. We observed higher levels of hepatic immune cell infiltrations in both 3- and 6-mo-old Pi*Z mice compared with Pi*M as an indication of liver inflammation. Liver fibrosis was observed as accumulation of collagen in 6-mo-old Pi*Z liver tissues compared with Pi*M control mice. Furthermore, the transcriptomic analysis revealed a dysregulated liver immune response to LPS in Pi*Z mice compared with Pi*M. Of particular interest for translational work, this study aims to establish a mouse model of AATD with a strong manifestation of liver disease that will be a valuable in vivo tool to study the pathophysiology of AATD-mediated liver disease. Our data suggest that the human transgenic mouse model of AATD could provide a suitable model for the evaluation of therapeutic approaches and preventive reagents against AATD-mediated liver disease.NEW & NOTEWORTHY We have characterized a mouse model of human alpha-1 antitrypsin deficiency with a strong manifestation of liver disease that can be used as an in vivo tool to test preventive and therapeutic reagents. Our data explores the altered immunophenotype of alpha-1 antitrypsin-deficient liver macrophages and suggests a relationship between acute inflammation, immune response, and fibrosis.

Only one-third of referrals for fatty liver disease are on time: real-world study reveals opportunities to avoid unnecessary and delayed referrals

BACKGROUND AND AIMS

Fatty liver disease is a global health concern, but in the absence of specific guidelines, current referral patterns differ according to the preferences of the general practitioners. Outpatient Gastroenterology clinics spend futile resources on liver-healthy patients while diagnosing decompensated patients delayed. We aimed to describe referral patterns to a regional outpatient Gastroenterology clinic.

METHODS

We reviewed 9684 referrals from primary care for suspected liver disease in the years 2016-2017, during two years. Data were extracted from the patients' hospital records to assess the clinical workup and patient outcomes until a mean of 43 months after the time of referral. Referrals were categorized as unnecessary (no signs of liver disease), timely (significant fibrosis/compensated cirrhosis), or delayed (decompensated cirrhosis).

RESULTS

We included 375 patient referrals from primary care. The main reason for referral was elevated transaminases. More than half (54%) of patients had no signs of liver disease, being unnecessarily referred for evaluation, while 17% had decompensated liver disease and were thus referred too late.

CONCLUSIONS

Only one-third of patients referred on suspicion of liver disease were referred on time, either before presenting with decompensated liver cirrhosis or with some evidence of significant liver disease, e.g., liver fibrosis. There is a huge unmet need for clinical referral pathways in primary care. Strengths and Limitations of this StudyA strength of this study is the complete mapping of all potential referrals to the outpatient clinic in the two-year period. Instead of retrieving the historic data by ICD-10 diagnosis codes, and reflecting only those patients where the GP clearly suspects liver disease, we have a strong reliance on our methods. We screened all potentially relevant referrals, e.g., referrals due to weight loss or fatigue, which may reflect symptoms of cirrhosis. Thereby we are confident that we have not missed any patients that originally were referred with unspecific symptoms, but after evaluation are diagnosed with liver disease.Another strength of our study is the long follow-up period, which allows us to fully evaluate the course for the individual patient, and the potential later coming diagnoses.Finally, it is a strength of the study that we were not exclusive to one liver disease etiology, both ALD and NAFLD etiology were included in the study.A limitation of this study is the use of historic data, and the fact that it is a single-center study, showing only the referral patterns in one outpatient Gastroenterology clinic.

Caffeine alleviates acute liver injury by inducing the expression of NEDD4L and deceasing GRP78 level via ubiquitination

BACKGROUND

Acute liver injury is liver cell injury that occurs rapidly in a short period of time. Caffeine has been shown to maintain hepatoprotective effect with an unclear mechanism. Endoplasmic reticulum stress (ERS) has significant effects in acute liver injury. Induction of GRP78 is a hallmark of ERS. Whether or not caffeine's function is related to GRP78 remains to be explored.

METHODS

Acute liver injury model was established by LPS-treated L02 cells and in vivo administration of LPS/D-Gal in mice. Caffeine was pre-treated in L02 cells or mice. Gene levels was determined by real-time PCR and western blot. Cell viability was tested by CCK-8 assay and cell apoptosis was tested by flow cytometry. The interaction of GRP78 and NEDD4L was determined by Pull-down and co-immunoprecipitation (Co-IP) assay. The ubiquitination by NEDD4L on GRP78 was validated by in vitro ubiquitination assay.

RESULTS

Caffeine protected liver cells against acute injury induced cell apoptosis and ERS both in vitro and in vivo. Suppression of GRP78 could block the LPS-induced cell apoptosis and ERS. NEDD4L was found to interact with GRP78 and ubiquitinate its lysine of 324 site directly. Caffeine treatment induced the expression of NEDD4L, resulting in the ubiquitination and inhibition of GRP78.

CONCLUSION

Caffeine mitigated the acute liver injury by stimulating NEDD4L expression, which inhibited GRP78 expression via ubiquitination at its K324 site. Low dose of caffeine could be a promising therapeutic treatment for acute liver injury.

Alpha-1 antitrypsin Pi∗Z allele is an independent risk factor for liver transplantation and death in patients with advanced chronic liver disease

Background & Aims

Alpha-1 antitrypsin (AAT) deficiency causes/predisposes individuals to advanced chronic liver disease (ACLD). However, the role of the SERPINA1 Pi∗Z allele in patients who have already progressed to ACLD is unclear. Thus, we aimed to evaluate the impact of the Pi∗Z allele on the risk of liver transplantation/liver-related death in patients with ACLD, while adjusting for the severity of liver disease at inclusion.

Methods

A total of 1,118 patients with ACLD who underwent hepatic venous pressure gradient (HVPG) measurement and genotyping for the Pi∗Z/Pi∗S allele at the Vienna Hepatic Hemodynamic Lab were included in this retrospective analysis. The outcome of interest was liver transplantation/liver-related death, while non-liver-related death and removal/suppression of the primary etiological factor were considered as competing risks.

Results

Viral hepatitis was the most common etiology (44%), followed by alcohol-related (31%) and non-alcoholic fatty liver disease (11%). Forty-two (4%) and forty-six (4%) patients harboured the Pi∗Z and Pi∗S variants, respectively. Pi∗Z carriers had more severe portal hypertension (HVPG: 19±6 vs.15±7 mmHg; p <0.001) and hepatic dysfunction (Child-Turcotte-Pugh: 7.1±1.9 vs. 6.5±1.9 points; p = 0.050) at inclusion, compared to non-carriers. Contrarily, the Pi∗S allele was unrelated to liver disease severity. In competing risk regression analysis, harbouring the Pi∗Z allele was significantly associated with an increased probability of liver transplantation/liver-related death, even after adjusting for liver disease severity at inclusion. The detrimental impact of the common Pi∗MZ genotype (adjusted subdistribution hazard ratio: ≈1.56 vs. Pi∗MM) was confirmed in a fully adjusted subgroup analysis. In contrast, Pi∗S carriers had no increased risk of events.

Conclusion

Genotyping for the Pi∗Z allele identifies patients with ACLD at increased risk of adverse liver-related outcomes, thereby improving prognostication. Therapies targeting the accumulation of abnormal AAT should be evaluated as disease-modifying treatments in Pi∗Z allele carriers with ACLD.

Lay summary

Alpha-1 antitrypsin deficiency is a genetic disease that affects the lung and the liver. Carrying two dysfunctional copies of the gene causes advanced liver disease. Harbouring one dysfunctional copy increases disease severity in patients with other liver illness. However, the significance of this genetic defect in patients who already suffer from advanced liver disease is unclear. Our study found that harbouring at least one dysfunctional copy of the alpha-1 antitrypsin gene increases the risk of requiring a liver transplantation or dying from a liver disease. This indicates the need for medical therapies aimed at treating the hepatic consequences of this genetic defect.

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Pi∗Z allele is significantly associated with liver-related events in patients with ACLD.

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This finding extends to patients harbouring the Pi∗MZ genotype.

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Genotyping for the Pi∗Z allele might improve prognostication in patients with ACLD.

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Therapies targeting accumulation of abnormal AAT should be assessed in Pi∗Z carriers with ACLD.

Orphan drug development in alpha-1 antitypsin deficiency

Alpha-1 antitrypsin deficiency (AATD, OMIM #613490) is a rare metabolic disorder affecting lungs and liver. The purpose of this study is to assess the impact of the US orphan drug act on AATD by providing a quantitative clinical-regulatory insight into the status of FDA orphan drug approvals and designations for compounds intended to treat AATD. This is across-sectional analysis of the FDA database for orphan drug designations. Primary endpoint: orphan drug approvals. Secondary endpoint: orphan drug designations by the FDA. Close of database was 16 July 2021. STROBE criteria were respected. Primary outcome: one compound, alpha-1-proteinase inhibitor (human) was approved as an orphan drug in 1987 with market exclusivity until 1994. Secondary outcome: sixteen compounds received FDA orphan drug designation including protein, anti-inflammatory, mucolytic, gene, or cell therapy. Drug development activities in AATD were comparable to other rare conditions and led to the FDA-approval of one compound, based on a relatively simple technological platform. The current unmet medical need to be addressed are extrapulmonary manifestations, in this case the AATD-associated liver disease. Orphan drug development is actually focusing on (1) diversified recombinant AAT production platforms, and (2) innovative gene therapies, which may encompass a more holistic therapeutic approach.

The unfolded protein response to PI*Z alpha-1 antitrypsin in human hepatocellular and murine models

Alpha-1 antitrypsin (AAT) deficiency (AATD) is an inherited disease caused by mutations in the serpin family A member 1 (SERPINA1, also known as AAT) gene. The most common variant, PI*Z (Glu342Lys), causes accumulation of aberrantly folded AAT in the endoplasmic reticulum (ER) of hepatocytes that is associated with a toxic gain of function, hepatocellular injury, liver fibrosis, and hepatocellular carcinoma. The unfolded protein response (UPR) is a cellular response to improperly folded proteins meant to alleviate ER stress. It has been unclear whether PI*Z AAT elicits liver cell UPR, due in part to limitations of current cellular and animal models. This study investigates whether UPR is activated in a novel human PI*Z AAT cell line and a new PI*Z human AAT (hAAT) mouse model. A PI*Z AAT hepatocyte cell line (Huh7.5Z) was established using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing of the normal ATT (PI*MM) gene in the Huh7.5 cell line. Additionally, novel full-length genomic DNA PI*Z hAAT and PI*M hAAT transgenic mouse models were established. Using these new models, UPR in Huh7.5Z cells and PI*Z mice were comprehensively determined. Robust activation of UPR was observed in Huh7.5Z cells compared to Huh7.5 cells. Activated caspase cascade and apoptosis markers, increased chaperones, and autophagy markers were also detected in Z hepatocytes. Selective attenuation of UPR signaling branches was observed in PI*Z hAAT mice in which the protein kinase R-like ER kinase and inositol-requiring enzyme1α branches were suppressed while the activating transcription factor 6α branch remained active. This study provides direct evidence that PI*Z AAT triggers canonical UPR and that hepatocytes survive pro-apoptotic UPR by selective suppression of UPR branches. Our data improve understanding of underlying pathological molecular mechanisms of PI*Z AATD liver disease.

Fazirsiran for Liver Disease Associated with Alpha1-Antitrypsin Deficiency

BACKGROUND

Alpha₁-antitrypsin (AAT) deficiency results from carriage of a homozygous SERPINA1 "Z" mutation (proteinase inhibitor [PI] ZZ). The Z allele produces a mutant AAT protein called Z-AAT, which accumulates in hepatocytes and can lead to progressive liver disease and fibrosis. This open-label, phase 2 trial investigated the safety and efficacy of fazirsiran, an RNA interference therapeutic, in patients with liver disease associated with AAT deficiency.

METHODS

We assigned adults with the PI ZZ genotype and liver fibrosis to receive fazirsiran at a dose of 200 mg (cohorts 1 [4 patients] and 2 [8 patients]) or 100 mg (cohort 1b [4 patients]) subcutaneously on day 1 and week 4 and then every 12 weeks. The primary end point was the change from baseline to week 24 (cohorts 1 and 1b) or week 48 (cohort 2) in liver Z-AAT concentrations, which were measured by means of liquid chromatography-mass spectrometry.

RESULTS

All the patients had reduced accumulation of Z-AAT in the liver (median reduction, 83% at week 24 or 48). The nadir in serum was a reduction of approximately 90%, and treatment was also associated with a reduction in histologic globule burden (from a mean score of 7.4 [scores range from 0 to 9, with higher scores indicating a greater globule burden] at baseline to 2.3 at week 24 or 48). All cohorts had reductions in liver enzyme concentrations. Fibrosis regression was observed in 7 of 15 patients and fibrosis progression in 2 of 15 patients after 24 or 48 weeks. There were no adverse events leading to trial or drug discontinuation. Four serious adverse events (viral myocarditis, diverticulitis, dyspnea, and vestibular neuronitis) resolved.

CONCLUSIONS

In this small trial, fazirsiran was associated with a strong reduction of Z-AAT concentrations in the serum and liver and concurrent improvements in liver enzyme concentrations. (Funded by Arrowhead Pharmaceuticals; AROAAT-2002 ClinicalTrials.gov number, NCT03946449.).

[Alpha 1-antitrypsin deficiency]

INTRODUCTION

Pulmonary emphysema and liver disease are the clinical expressions of alpha 1-antitrypsin deficiency, an autosomal recessive genetic disease.

STATE OF THE ART

Alpha 1-antitrypsin deficiency is usually associated with the homozygous Z variant of the SERPINA1 gene. Its clinical expression always consists in a substantial reduction of alpha 1-antitrypsin serum concentration and its variants are analyzed by isoelectric focalization or molecular techniques. Assessed by CO transfer alteration and CT scan, risk of pulmonary emphysema is increased by tobacco consumption. Assessed by transient elastography and liver ultrasound, risk of liver disease is increased by alcohol consumption or obesity. Treatment of COPD-associated alpha 1-antitrypsin deficiency does not differ from that of other forms of COPD. In patients presenting with severe deficiency, augmentation therapy with plasma-derived alpha 1-antitrypsin reduces the progression of emphysema, as shown in terms of CT-based lung density metrics. Patients with alpha 1-antitrypsin deficiency with a ZZ genotype should refrain from alcohol or tobacco consumption, and watch their weight; so should their close relatives.

PERSPECTIVES

Modulation of alpha 1-antitrypsin liver production offers an interesting new therapeutic perspective.

CONCLUSION

Homozygous (Z) variants of the SERPINA1 gene confer an increased risk of pulmonary emphysema and liver disease, particularly among smokers, drinkers and obese persons.

Hepatic decompensation is accelerated in patients with cirrhosis and alpha-1 antitrypsin Pi∗MZ genotype

Background & Aims

Alpha-1 antitrypsin deficiency is caused by mutations in SERPINA1, most commonly homozygosity for the Pi∗Z variant, and can present as liver disease. While heterozygosity for Pi∗Z (Pi∗MZ) is linked to increased risk of cirrhosis, whether the Pi∗MZ genotype is associated with an increased rate of decompensation among patients who already have compensated cirrhosis is not known.

Methods

This was a retrospective study of Michigan Genomics Initiative participants with baseline compensated cirrhosis. The primary predictors were Pi∗MZ or Pi∗MS genotype (vs. Pi∗MM). The primary outcomes were hepatic decompensation with ascites, hepatic encephalopathy, or variceal bleeding, or the combined endpoint of liver-related death or liver transplant, both modeled with Fine-Gray competing risk models.

Results

We included 576 patients with baseline compensated cirrhosis who had undergone genotyping, of whom 474 had Pi∗MM, 49 had Pi∗MZ, and 52 had Pi∗MS genotypes. Compared to Pi∗MM genotype, Pi∗MZ was associated with increased rates of hepatic decompensation (hazard ratio 1.81; 95% CI 1.22-2.69; p = 0.003) and liver transplant or liver-related death (hazard ratio 2.07; 95% CI 1.21-3.52; p = 0.078). These associations remained significant after adjustment for severity of underlying liver disease, and were robust across subgroup analyses based on etiology, sex, obesity, and diabetes status. Pi∗MS was not associated with decompensation or death/transplantation.

Conclusions

The SERPINA1 Pi∗MZ genotype is associated with an increased rate of hepatic decompensation and decreased transplant-free survival among patients with baseline compensated cirrhosis.

Lay summary

There is a mutation in the gene SERPINA1 called Pi∗MZ which increases risk of liver scarring (cirrhosis); however, it is not known what effect Pi∗MZ has if someone already has cirrhosis. In this study, we found that people who had cirrhosis and Pi∗MZ developed complications from cirrhosis faster than those who did not have the mutation.

Alpha-1 antitrypsin deficiency: A re-surfacing adult liver disorder

Alpha-1 antitrypsin deficiency (AATD) arises from mutations in the SERPINA1 gene encoding alpha-1 antitrypsin (AAT) that lead to AAT retention in the endoplasmic reticulum of hepatocytes, causing proteotoxic liver injury and loss-of-function lung disease. The homozygous Pi∗Z mutation (Pi∗ZZ genotype) is responsible for the majority of severe AATD cases and can precipitate both paediatric and adult liver diseases, while the heterozygous Pi∗Z mutation (Pi∗MZ genotype) is an established genetic modifier of liver disease. We review genotype-related hepatic phenotypes/disease predispositions. We also describe the mechanisms and factors promoting the development of liver disease, as well as approaches to evaluate the extent of liver fibrosis. Finally, we discuss emerging diagnostic and therapeutic approaches for the clinical management of this often neglected disorder.

Disease burden associated with alpha-1 antitrypsin deficiency: systematic and structured literature reviews

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disorder characterised by reduced levels of circulating alpha-1 antitrypsin and an increased risk of lung and liver disease. Recent reviews of AATD have focused on diagnosis, epidemiology and clinical management; comprehensive reviews examining disease burden are lacking. Therefore, we conducted literature reviews to investigate the AATD disease burden for patients, caregivers and healthcare systems. Embase, PubMed and Cochrane libraries were searched for AATD publications from database inception to June 2021, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Most published AATD studies were small and short in duration, with variations in populations, designs, measures and outcomes, complicating cross-study comparisons. AATD was associated with significant pulmonary and hepatic morbidity. COPD, emphysema and bronchiectasis were common lung morbidities, where smoking was a key risk factor. Fibrosis and steatosis were the most common liver complications reported in patients with a PiZ allele. Health status analyses suggested a poorer quality of life for AATD patients diagnosed with COPD versus those with non-AATD-associated COPD. The burden for caregivers included loss of personal time due to caring responsibilities, stress and anxiety. AATD was also associated with high direct medical costs and healthcare resource utilisation.

The Relationship between Plasma Alpha-1-Antitrypsin Polymers and Lung or Liver Function in ZZ Alpha-1-Antitrypsin-Deficient Patients

Alpha-1-Antitrypsin (AAT) is a protein of the SERPINA1 gene. A single amino acid mutation (Lys342Glu) results in an expression of misfolded Z-AAT protein, which has a high propensity to intra- and extra-cellular polymerization. Here, we asked whether levels of circulating Z-AAT polymers are associated with the severity of lung disease, liver disease, or both. We obtained cross sectional data from the Dutch part of the Alpha1 International Registry of 52 ZZ-AAT patients who performed a pulmonary function test and donated a blood sample on the same day. From the Alpha-1 Liver Aachen Registry, we obtained a cohort of 40 ZZ-AAT patients with available data on their liver function. The levels of plasma Z-AAT polymers were determined using a LG96 monoclonal antibody-based sandwich ELISA. In a Dutch cohort, the median plasma level of Z-AAT polymers of patients diagnosed for pulmonary disease was 947.5 µg/mL (733.6−1218 µg/mL (95% CI)), which did not correlate with airflow obstruction or gas transfer value. In the Alpha-1 liver patient cohort, the median polymer level was 1245.9 µg/mL (753−2034 µg/mL (95% CI)), which correlated with plasma gamma-glutamyl transferase (GGT, rs = 0.57, p = 0.001), glutamate dehydrogenase (GLDH, rs = 0.48, p = 0.002) and triglycerides (TG, rs = 0.48, p = 0.0046). A Wilcoxon rank test showed higher Z-AAT polymer values for the liver over the lung group (p < 0.0001). These correlations support a possible link between plasma Z-AAT polymers and the liver function.

An Italian expert consensus on the management of alpha1-antitrypsin deficiency: a comprehensive set of algorithms

BACKGROUND

Alpha1-antitrypin deficiency (AATD) is a genetic-based risk condition, mainly affecting the lungs and liver. Despite its wide distribution, it is largely underdiagnosed, thus being considered a rare disease, and is consequently managed in ad hoc reference centers. Unfortunately, an easy-to-use algorithm for managing such a complex disease is still lacking.

METHODS

An expert consensus meeting was conducted among experts in the management of AATD to build a comprehensive algorithm, including diagnosis, monitoring, AAT therapy, rehabilitation and lung transplantation, and liver disease, that could serve as a guide for physicians and treating centers. A panel of AATD specialists evaluated the results of their work.

RESULTS

Diagnosis is the most delicate phase, and awareness about this condition should be raised among GPs. A set of recommendations has been written about the most suitable follow-up visits. Augmentation therapy with AAT may be useful to reduce the progression of emphysema and lung function decline in selected patients. Exercise capacity may be improved by pulmonary rehabilitation and, in selected cases, by lung volume reduction or lung transplantation. Support therapies are needed for those who develop liver disease, and, in selected cases, liver transplantation may be considered. Patients should be carefully educated about their lifestyle, including smoking cessation, body weight control, and reduced alcohol intake.

CONCLUSIONS

The proposed algorithm obtained the endorsement of the Italian Society of Pneumology (SIP). However, further studies and additional clinical data are required to confirm the validity of these recommendations.

Hepatobiliary phenotypes of adults with alpha-1 antitrypsin deficiency

OBJECTIVE

Alpha-1 antitrypsin deficiency (AATD) is a common, potentially lethal inborn disorder caused by mutations in alpha-1 antitrypsin (AAT). Homozygosity for the 'Pi*Z' variant of AAT (Pi*ZZ genotype) causes lung and liver disease, whereas heterozygous 'Pi*Z' carriage (Pi*MZ genotype) predisposes to gallstones and liver fibrosis. The clinical significance of the more common 'Pi*S' variant remains largely undefined and no robust data exist on the prevalence of liver tumours in AATD.

DESIGN

Baseline phenotypes of AATD individuals and non-carriers were analysed in 482 380 participants in the UK Biobank. 1104 participants of a multinational cohort (586 Pi*ZZ, 239 Pi*SZ, 279 non-carriers) underwent a comprehensive clinical assessment. Associations were adjusted for age, sex, body mass index, diabetes and alcohol consumption.

RESULTS

Among UK Biobank participants, Pi*ZZ individuals displayed the highest liver enzyme values, the highest occurrence of liver fibrosis/cirrhosis (adjusted OR (aOR)=21.7 (8.8-53.7)) and primary liver cancer (aOR=44.5 (10.8-183.6)). Subjects with Pi*MZ genotype had slightly elevated liver enzymes and moderately increased odds for liver fibrosis/cirrhosis (aOR=1.7 (1.2-2.2)) and cholelithiasis (aOR=1.3 (1.2-1.4)). Individuals with homozygous Pi*S mutation (Pi*SS genotype) harboured minimally elevated alanine aminotransferase values, but no other hepatobiliary abnormalities. Pi*SZ participants displayed higher liver enzymes, more frequent liver fibrosis/cirrhosis (aOR=3.1 (1.1-8.2)) and primary liver cancer (aOR=6.6 (1.6-26.9)). The higher fibrosis burden was confirmed in a multinational cohort. Male sex, age ≥50 years, obesity and the presence of diabetes were associated with significant liver fibrosis.

CONCLUSION

Our study defines the hepatobiliary phenotype of individuals with the most relevant AATD genotypes including their predisposition to liver tumours, thereby allowing evidence-based advice and individualised hepatological surveillance.

Liver Fibrosis-From Mechanisms of Injury to Modulation of Disease

The Transregional Collaborative Research Center "Organ Fibrosis: From Mechanisms of Injury to Modulation of Disease" (referred to as SFB/TRR57) was funded for 13 years (2009-2021) by the German Research Council (DFG). This consortium was hosted by the Medical Schools of the RWTH Aachen University and Bonn University in Germany. The SFB/TRR57 implemented combined basic and clinical research to achieve detailed knowledge in three selected key questions: (i) What are the relevant mechanisms and signal pathways required for initiating organ fibrosis? (ii) Which immunological mechanisms and molecules contribute to organ fibrosis? and (iii) How can organ fibrosis be modulated, e.g., by interventional strategies including imaging and pharmacological approaches? In this review we will summarize the liver-related key findings of this consortium gained within the last 12 years on these three aspects of liver fibrogenesis. We will highlight the role of cell death and cell cycle pathways as well as nutritional and iron-related mechanisms for liver fibrosis initiation. Moreover, we will define and characterize the major immune cell compartments relevant for liver fibrogenesis, and finally point to potential signaling pathways and pharmacological targets that turned out to be suitable to develop novel approaches for improved therapy and diagnosis of liver fibrosis. In summary, this review will provide a comprehensive overview about the knowledge on liver fibrogenesis and its potential therapy gained by the SFB/TRR57 consortium within the last decade. The kidney-related research results obtained by the same consortium are highlighted in an article published back-to-back in Frontiers in Medicine.

Non-invasive diagnosis and follow-up of rare genetic liver diseases

Rare genetic liver diseases can result in multi-systemic damage, which may compromise the patient's prognosis. Wilson's disease and alpha-1 antitrypsin deficiency must be investigated in any patient with unexplained liver disease. Cystic fibrosis screening of new-borns is now implemented in most high-prevalence countries. The diagnosis of these diseases can be strongly suggested with specific non-invasive tests. Molecular analysis gene for these diseases is long and tedious but is recommended to confirm the diagnosis and help for the family screening. Liver biopsy is not systematic and is discussed when it helps diagnosis. Currently, for these three diseases, non-invasive fibrosis markers could identify patients with risk of cirrhosis and complications. Rare genetic liver diseases can result in multi-systemic damage, which may compromise the patient's prognosis. Wilson's disease, must be investigated in any patient with unexplained liver disease and/or unexplained neurological or neuropsychiatric disorders. The diagnosis is based on a combination of clinical, biological features, including copper balance. The exchangeable copper/total copper ratio is a new sensible and specific biological marker, useful for the diagnosis of the disease. Timely diagnosis and treatment will prevent serious complications from the disease. Neurological evaluation and familial screening are essential in patients with Wilson's disease.

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.

Protein Aggregation in the ER: Calm behind the Storm

As one of the largest organelles in eukaryotic cells, the endoplasmic reticulum (ER) plays a vital role in the synthesis, folding, and assembly of secretory and membrane proteins. To maintain its homeostasis, the ER is equipped with an elaborate network of protein folding chaperones and multiple quality control pathways whose cooperative actions safeguard the fidelity of protein biogenesis. However, due to genetic abnormalities, the error-prone nature of protein folding and assembly, and/or defects or limited capacities of the protein quality control systems, nascent proteins may become misfolded and fail to exit the ER. If not cleared efficiently, the progressive accumulation of misfolded proteins within the ER may result in the formation of toxic protein aggregates, leading to the so-called “ER storage diseases”. In this review, we first summarize our current understanding of the protein folding and quality control networks in the ER, including chaperones, unfolded protein response (UPR), ER-associated protein degradation (ERAD), and ER-selective autophagy (ER-phagy). We then survey recent research progress on a few ER storage diseases, with a focus on the role of ER quality control in the disease etiology, followed by a discussion on outstanding questions and emerging concepts in the field.

Alpha-1 Antitrypsin and Hepatocellular Carcinoma in Liver Cirrhosis: SERPINA1 MZ or MS Genotype Carriage Decreases the Risk

Heterozygotes for Z or S alleles of alpha-1-antrypsin (AAT) have low serum AAT levels. Our aim was to compare the risk of hepatocellular carcinoma (HCC) in patients with liver cirrhosis carrying the SERPINA1 MM, MZ and MS genotypes. The study groups consisted of 1119 patients with liver cirrhosis of various aetiologies, and 3240 healthy individuals served as population controls. The MZ genotype was significantly more frequent in the study group (55/1119 vs. 87/3240, p < 0.0001). The MS genotype frequency was comparable in controls (32/119 vs. 101/3240, p = 0.84). MZ and MS heterozygotes had lower serum AAT level than MM homozygotes (medians: 0.90 g/L; 1.40 g/L and 1.67 g/L; p < 0.001 for both). There were significantly fewer patients with HCC in the cirrhosis group among MZ and MS heterozygotes than in MM homozygotes (5/55 and 1/32 respectively, vs. 243/1022, p < 0.01 for both). The risk of HCC was lower in MZ and MS heterozygotes than in MM homozygotes (OR 0.3202; 95% CI 0.1361–0.7719 and OR 0.1522; 95% CI 0.02941–0.7882, respectively). Multivariate analysis of HCC risk factors identified MZ or MS genotype carriage as a protective factor, whereas age, male sex, BMI and viral aetiology of cirrhosis increased HCC risk.

Quantitative measurement of the histological features of alpha-1 antitrypsin deficiency-associated liver disease in biopsy specimens

Background

Pathological mutations in Alpha-1 Antitrypsin (AAT) protein cause retention of toxic polymers in the hepatocyte endoplasmic reticulum. The risk for cirrhosis in AAT deficiency is likely directly related to retention of these polymers within the liver. Polymers are classically identified on liver biopsy as inclusion bodies by periodic acid schiff staining after diastase treatment and immunohistochemistry. However, characterization of the polymer burden within a biopsy sample is limited to a semi-quantitative scale as described by a pathologist. Better methods to quantify polymer are needed to advance our understanding of pathogenesis of disease. Therefore, we developed a method to quantify polymer aggregation from standard histologic specimens. In addition, we sought to understand the relationship of polymer burden and other histologic findings to the presence of liver fibrosis.

Methods

Liver samples from a well-categorized AATD cohort were used to develop histo-morphometric tools to measure protein aggregation.

Results

Whole-slide morphometry reliably quantifies aggregates in AATD individuals. Despite very low levels of inclusions present (0–0.41%), accumulation of globules is not linear and is associated with higher fibrosis stages. Immunohistochemistry demonstrates that fibrosis is associated with polymer accumulation and not total AAT. A proportion of patients were found to be “heavy accumulators” with a polymer burden above the upper 25% of normal distribution. Males had significantly more liver inclusions and polymer than females. These measurements also highlight interrelated phenotypes of hepatocellular degeneration and autophagy in AATD liver disease.

Conclusion

Quantitative inclusion analysis measures AAT accumulation in liver biopsy specimens. Quantification of polymer may identify individuals at risk for progressive disease and candidates for therapeutic interventions. Furthermore, these methods may be useful for evaluating efficacy of drugs targeting accumulation of AAT.

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.

Heterozygosity of the Alpha 1-Antitrypsin Pi*Z Allele and Risk of Liver Disease

The serpin family A member 1 (SERPINA1) Z allele is present in approximately one in 25 individuals of European ancestry. Z allele homozygosity (Pi*ZZ) is the most common cause of alpha 1-antitrypsin deficiency and is a proven risk factor for cirrhosis. We examined whether heterozygous Z allele (Pi*Z) carriers in United Kingdom (UK) Biobank, a population-based cohort, are at increased risk of liver disease. We replicated findings in Massachusetts General Brigham Biobank, a hospital-based cohort. We also examined variants associated with liver disease and assessed for gene-gene and gene-environment interactions. In UK Biobank, we identified 1,493 cases of cirrhosis, 12,603 Z allele heterozygotes, and 129 Z allele homozygotes among 312,671 unrelated white British participants. Heterozygous carriage of the Z allele was associated with cirrhosis compared to noncarriage (odds ratio [OR], 1.53; P = 1.1×10^-04); homozygosity of the Z allele also increased the risk of cirrhosis (OR, 11.8; P = 1.8 × 10^-09). The OR for cirrhosis of the Z allele was comparable to that of well-established genetic variants, including patatin-like phospholipase domain containing 3 (PNPLA3) I148M (OR, 1.48; P = 1.1 × 10^-22) and transmembrane 6 superfamily member 2 (TM6SF2) E167K (OR, 1.34; P = 2.6 × 10^-06). In heterozygotes compared to noncarriers, the Z allele was associated with higher alanine aminotransferase (ALT; P = = 4.6 × 10^-46), aspartate aminotransferase (AST; P = 2.2 × 10^-27), alkaline phosphatase (P = 3.3 × 10^-43), gamma-glutamyltransferase (P = 1.2 × 10^-05), and total bilirubin (P = 6.4 × 10^-06); Z allele homozygotes had even greater elevations in liver biochemistries. Body mass index (BMI) amplified the association of the Z allele for ALT (P interaction = 0.021) and AST (P interaction = 0.0040), suggesting a gene-environment interaction. Finally, we demonstrated genetic interactions between variants in PNPLA3, TM6SF2, and hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13); there was no evidence of epistasis between the Z allele and these variants. Conclusion: SERPINA1 Z allele heterozygosity is an important risk factor for liver disease; this risk is amplified by increasing BMI.

[Alpha-1 antitrypsin deficiency: cause and cofactor for liver disease]

Alpha-1-antitrypsin deficiency (AATD) is a genetic disorder arising due to mutation in alpha1-antitrypsin (AAT). AAT mutations interfere with the AAT production/secretion, cause decreased AAT serum levels and accumulation of AAT in the liver. The excess AAT leads to a proteotoxic liver disease, while the lack of AAT in systemic circulation predisposes to lung injury. While AATD related lung disease is well understood, liver disease needs further awareness. Non-invasive liver stiffness measurement constitutes a useful method to estimate the extent of liver fibrosis. Significant liver fibrosis occurs in 20-35 % of individuals with the classic, severe genotype Pi*ZZ. Genotype Pi*SZ, also known as the compound heterozygous form, confers an increased risk of both liver fibrosis and liver neoplasia. Even the heterozygous genotype Pi*MZ increases the odds of fibrosis in presence of further risk factors such as obesity, male sex, metabolic syndrome and diabetes mellitus. In individuals with non-alcoholic fatty liver disease or alcohol misuse it promotes the development of liver cirrhosis. While no drug treatment exists for AATD-related liver disease, there are several compounds in clinical phase II/III-trials. These either silence the AAT production via siRNA or facilitate the secretion of AAT from the liver due to an improved folding.

The Importance of N186 in the Alpha-1-Antitrypsin Shutter Region Is Revealed by the Novel Bologna Deficiency Variant

Alpha-1-antitrypsin (AAT) deficiency causes pulmonary disease due to decreased levels of circulating AAT and consequently unbalanced protease activity in the lungs. Deposition of specific AAT variants, such as the common Z AAT, within hepatocytes may also result in liver disease. These deposits are comprised of ordered polymers of AAT formed by an inter-molecular domain swap. The discovery and characterization of rare variants of AAT and other serpins have historically played a crucial role in the dissection of the structural mechanisms leading to AAT polymer formation. Here, we report a severely deficient shutter region variant, Bologna AAT (N186Y), which was identified in five unrelated subjects with different geographical origins. We characterized the new variant by expression in cellular models in comparison with known polymerogenic AAT variants. Bologna AAT showed secretion deficiency and intracellular accumulation as detergent-insoluble polymers. Extracellular polymers were detected in both the culture media of cells expressing Bologna AAT and in the plasma of a patient homozygous for this variant. Structural modelling revealed that the mutation disrupts the hydrogen bonding network in the AAT shutter region. These data support a crucial coordinating role for asparagine 186 and the importance of this network in promoting formation of the native structure.