[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.

Hepatocyte proteomes reveal the role of protein disulfide isomerase 4 in alpha 1-antitrypsin deficiency

Background & Aims

A single point mutation in the Z-variant of alpha 1-antitrypsin (Z-AAT) alone can lead to both a protein folding and trafficking defect, preventing its exit from the endoplasmic reticulum (ER), and the formation of aggregates that are retained as inclusions within the ER of hepatocytes. These defects result in a systemic AAT deficiency (AATD) that causes lung disease, whereas the ER-retained aggregates can induce severe liver injury in patients with ZZ-AATD. Unfortunately, therapeutic approaches are still limited and liver transplantation represents the only curative treatment option. To overcome this limitation, a better understanding of the molecular basis of ER aggregate formation could provide new strategies for therapeutic intervention.

Methods

Our functional and omics approaches here based on human hepatocytes from patients with ZZ-AATD have enabled the identification and characterisation of the role of the protein disulfide isomerase (PDI) A4/ERP72 in features of AATD-mediated liver disease.

Results

We report that 4 members of the PDI family (PDIA4, PDIA3, P4HB, and TXNDC5) are specifically upregulated in ZZ-AATD liver samples from adult patients. Furthermore, we show that only PDIA4 knockdown or alteration of its activity by cysteamine treatment can promote Z-AAT secretion and lead to a marked decrease in Z aggregates. Finally, detailed analysis of the Z-AAT interactome shows that PDIA4 silencing provides a more conducive environment for folding of the Z mutant, accompanied by reduction of Z-AAT-mediated oxidative stress, a feature of AATD-mediated liver disease.

Conclusions

PDIA4 is involved in AATD-mediated liver disease and thus represents a therapeutic target for inhibition by drugs such as cysteamine. PDI inhibition therefore represents a potential therapeutic approach for treatment of AATD.

Lay summary

Protein disulfide isomerase (PDI) family members, and particularly PDIA4, are upregulated and involved in alpha 1-antitrypsin deficiency (AATD)-mediated liver disease in adults. PDI inhibition upon cysteamine treatment leads to improvements in features of AATD and hence represents a therapeutic approach for treatment of AATD-mediated liver disease.

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PDIA4 is upregulated and involved in alpha 1-antitrypsin deficiency (AATD)-mediated liver disease in adults.

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Knockdown of PDIA4 by siRNA or inhibition upon cysteamine treatment leads to improvements in features of AATD.

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RNA interference against PDIA4 or cysteamine represent approaches for treatment of AATD-mediated liver disease.

Incidental alpha-1-antitrypsin deficiency found in post-transplant liver allografts: Report of two cases

Alpha-1 antitrypsin deficiency is an autosomal recessive disease most commonly caused by misfolding of the Alpha-1-antitrypsin protein, which prevents its release from hepatocytes into the systemic circulation. This results in increased lifetime risk of liver and lung disease. Due to its variable penetrance, presentation and natural history, patients with alpha-1 antitrypsin deficiency are often underdiagnosed. In this report, we present two cases of alpha-1 antitrypsin deficiency in deceased-donor liver transplant allografts diagnosed post-transplant. There is currently no known adverse outcome directly linked to alpha-1 antitrypsin deficiency in the immediate post-transplant follow-up period. Thus, these allografts should not be excluded from transplantation.

Functional characterization of a SNP (F51S) found in human alpha 1-antitrypsin

BACKGROUND

Alpha 1-antitrypsin (A1AT) deficiency is related to lung and liver diseases, including pulmonary emphysema and liver cirrhosis in humans. Genetic variations including single nucleotide polymorphisms (SNPs) of SERPINA1 are responsible for A1AT deficiency, but the characteristics of the SNPs are not well-understood. Here, we investigated the features of a rare SNP (F51S) of A1AT, which introduces an additional N-glycosylation site in the N-terminal region of A1AT.

METHODS

We evaluated the F51S variant compared with the wild-type (WT) A1AT with regard to expression in CHO-K1 cells, trypsin inhibitory activity, polymerization, and thermal stability.

RESULTS

The recombinant F51S protein expressed in CHO-K1 cells was mostly retained inside cells. The F51S variant had trypsin inhibitory activity, but reduced thermal stability compared with the WT A1AT. The native acrylamide gel data showed that F51S tended to prevent polymerization of A1AT.

CONCLUSION

The results of this study indicate that Phe51 and the surrounding hydrophobic residue cluster plays an important role in the conformation and secretion of A1AT and suggest the harmful effects of a rare F51S SNP in human health.

Impact of a Health Management Program on Healthcare Outcomes among Patients on Augmentation Therapy for Alpha 1-Antitrypsin Deficiency: An Insurance Claims Analysis

Introduction

Alpha 1-antitrypsin deficiency (AATD) is a genetic disorder which reduces serum alpha 1-antitrypsin (AAT or alpha1-proteinase inhibitor, A1PI) and increases the risk of chronic obstructive pulmonary disease (COPD). Management strategies include intravenous A1PI augmentation, and, in some cases, a health management program (Prolastin Direct^®; PD).

Objectives

This study compared clinical and economic outcomes between patients with and without PD program participation.

Methods

This retrospective study included commercial and Medicare Advantage health insurance plan members with ≥ 1 claim with diagnosis codes for COPD and ≥ 1 medical or pharmacy claim including A1PI (on index date). Outcomes were compared between patients receiving only Prolastin^® or Prolastin^®-C (PD cohort) and patients who received a different brand without PD (Comparator cohort). Demographic and clinical characteristics were captured during 6 months pre-index. Post-index exacerbation episodes and healthcare utilization and costs were compared between cohorts.

Results

The study sample comprised 445 patients (n = 213 in PD cohort; n = 232 in Comparator cohort), with a mean age 55.5 years, 50.8% male, and 78.9% commercially insured. The average follow-up was 822 days (2.25 years), and the average time on A1PI was 747 days (2.04 years). Few differences were observed in demographic or clinical characteristics. Adjusting for differences in patient characteristics, the rate of severe exacerbation episodes was reduced by 36.1% in the PD cohort. Adjusted total annual all-cause costs were 11.4% lower, and adjusted mean respiratory-related costs were 10.6% lower in the PD cohort than the Comparator cohort. Annual savings in all-cause total costs in the PD cohort relative to the Comparator cohort was US$25,529 per patient, largely due to significantly fewer and shorter hospitalizations.

Conclusions

These results suggest that comprehensive health management services may improve both clinical and economic outcomes among patients with COPD and AATD who receive augmentation therapy.

Funding

Grifols Shared Services of North America, Inc.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0690-4) contains supplementary material, which is available to authorized users.

Liver disease in adults with α1-antitrypsin deficiency

Background

The natural history of adult liver disease due to α1-antitrypsin deficiency (A1AD) remains poorly understood.

Objective

We investigated whether heterozygosity for the Z-allele predisposes for the development of clinically significant portal hypertension (CSPH). Moreover, we aimed to non-invasively assess the prevalence of liver fibrosis and hepatic steatosis in adults with A1AD treated by pulmonologists.

Methods

SERPINA1 rs28929474 (Z-allele) was genotyped in 315 patients with CSPH (hepatic venous pressure gradient ≥10 mmHg; cases) and 248 liver donors (controls). In addition, 31 adults with A1AD (Pi*ZZ/Pi*SZ) and 11 first-degree relatives (Pi*MZ/Pi*MS) underwent liver stiffness and controlled attenuation parameter (CAP) measurement.

Results

Heterozygosity for the Z-allele was observed in 6.7% of patients with CSPH and 2.8% of liver donors. Thus, harboring the Z-allele was associated with increased odds of CSPH (odds ratio: 2.47; 95% confidence interval: 1.03-5.9; P = 0.042). Among Pi*ZZ/Pi*SZ patients, 23%/3% had liver stiffness values indicative of liver fibrosis ( ≥F2/ ≥F3). Interestingly, 65%/52% of Pi*ZZ/Pi*SZ patients had CAP values indicative of hepatic steatosis ( ≥S1/ ≥S2).

Conclusions

Heterozygosity for the Z-allele predisposes for the development of CSPH, confirming its role as a genetic (co)factor in liver disease. Pi*ZZ/SZ patients rarely develop liver fibrosis ≥F3 during adulthood; however, liver fibrosis ≥F2 is common. Elevated CAP values hint at underlying hepatic steatosis, which might promote liver fibrosis progression.

Results from a large targeted screening program for alpha-1-antitrypsin deficiency: 2003 - 2015

Background

Alpha-1-antitrypsin deficiency (AATD) is an autosomal codominant inherited disease that is significantly underdiagnosed. We have previously shown that the combination of an awareness campaign with the offer of free diagnostic testing results in the detection of a relevant number of severely deficient AATD patients. The present study provides an update on the results of our targeted screening program (German AAT laboratory, University of Marburg) covering a period from August 2003 to May 2015.

Methods

Diagnostic AATD detection test kits were offered free of charge. Dried blood samples were sent to our laboratory and used for the semiquantitative measurement of the AAT-level (nephelometry) and the detection of the S- or Z-allele (PCR). Isoelectric focusing was performed when either of the initial tests was indicative for at least one mutation. Besides, we evaluated the impact of additional screening efforts and the changes of the detection rate over time, and analysed the relevance of clinical parameters in the prediction of severe AATD.

Results

Between 2003 and 2015, 18,638 testing kits were analysed. 6919 (37.12 %) carried at least one mutation. Of those, we identified 1835 patients with severe AATD (9.82 % of the total test population) including 194 individuals with rare genotypes. Test initiatives offered to an unselected population resulted in a dramatically decreased detection rate. Among clinical characteristics, a history of COPD, emphysema, and bronchiectasis were significant predictors for Pi*ZZ, whereas a history of asthma, cough and phlegm were predictors of not carrying the genotype Pi*ZZ.

Conclusion

A targeted screening program, combining measures to increase awareness with cost-free diagnostic testing, resulted in a high rate of AATD detection. The clinical data suggest that testing should be primarily offered to patients with COPD, emphysema, and/or bronchiectasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-016-0453-8) contains supplementary material, which is available to authorized users.

A rare case of alpha 1-antitrypsin deficiency associated with hypogammaglobulinemia and recurrent pulmonary thrombosis

Alpha 1-antitrypsin (AAT) belongs to the family of serpins (serine protease inhibitors). Loop sheet polymerization is the pathology behind serpinopathies which encompasses AAT, anti-thrombin III and neuroserpin deficiency. To the best of our knowledge, we report the first case of alpha 1-antitrypsin deficiency associated with hypogammaglobulinemia and recurrent pulmonary thrombosis without any concomitant use of drugs.

Identification of compound heterozygous mutation in a Korean patient with alpha 1-antitrypsin deficiency

Alpha 1-antitrypsin (AAT) deficiency is a genetic disorder that primarily affects the lungs and liver. While AAT deficiency is one of the most common genetic disorders in the Caucasian population, it is extremely rare in Asians. Here, we report the case of a 36-year-old Korean woman with AAT deficiency who visited the emergency department of our hospital for the treatment of progressive dyspnea that had begun 10 years ago. She had never smoked. Chest computed tomography revealed panlobular emphysema in both lungs, which suggested AAT deficiency. The serum AAT level was 33 mg/dL (reference interval: 90-200 mg/dL). Four exons of the SERPINA1 gene, which is responsible for AAT deficiency, and their flanking regions were analyzed by PCR-direct sequencing. The patient was found to have 1 missense mutation (c.230C>T, p.Ser77Phe; S_iiyama) and 1 frameshift mutation (c.1158dupC, p.Glu387ArgfsX14; QO_clayton). This is the first Korean case of AAT deficiency confirmed by genetic analysis and the second case of a compound heterozygote of S_iiyama and QO_clayton, the first case of which was reported from Japan.