Wegener's granulomatosis and alpha1-antitrypsin-deficiency emphysema: proteinase-related diseases

SERPINA1 Gene Variants in Granulomatosis with Polyangiitis

Alpha-1 antitrypsin (A1AT) deficiency is one of the most common genetic disorders in Caucasian population. There is a link between granulomatosis with polyangiitis (GPA) and most frequent variants of SERPINA1 gene encoding severe alpha-1 antitripsin deficiency. However, the potential effect of Pi*Z, Pi*S as well as other SERPINA1 variants on clinical course of vasculitis are not well understood. The aim of the study was to analyze the potential effect of A1AT protein phenotype representing the SERPINA1 gene variants on the clinical course of GPA. The study group consisted of 64 subjects with GPA, stratified according to the disease severity: patients in active phase (group I, n = 12), patients during remission on treatment (group II, n = 40) or untreated (group III, n = 12). Normal Pi*MM SERPINA1 genotype was detected by means of real-time polymerase chain reaction (PCR) or direct sequencing in 59 patients, Pi*MZ genotype in 2, and Pi*IM, Pi*MS or Pi*SZ in 1 patient respectively. The patients with abnormal Pi*Z, Pi*S, or Pi*I allele constituted 17% in group I, 5% in group II, and 8% in group III. The serum content of A1AT and high sensitivity C-reactive protein (hsCRP) assessed by nephelometry did not differ between the groups. Interestingly, the mean serum antiPR3-antibodies level detected by Elisa method was significantly greater in the GPA patients with Pi*Z, Pi*S, or Pi*I SERPINA1 variants than in the Pi*MM homozygotes. In summary, heterozygous Pi*MZ, Pi*MS, and Pi*SZ genotype was detected in 7.8% of total group of GPA patients, and in 10.5% of those with lung lesions. The abnormal alleles of Pi*S and Pi*Z may affect the clinical course of the disease.

Tumor necrosis factor-α driven inflammation in alpha-1 antitrypsin deficiency: a new model of pathogenesis and treatment

Alpha-1 antitrypsin (AAT) deficiency (AATD) has traditionally been thought of as a genetic disorder characterized by lung destruction and early emphysema in a low AAT, and high neutrophil elastase (NE) environment in the lungs of affected individuals. Recently, a growing body of evidence has emerged to support the hypothesis that tumor necrosis factor alpha (TNF-α) is essential in the pathogenesis of both genetic AATD and non-genetic chronic obstructive pulmonary disease (COPD). Reports have highlighted the importance of TNF-α driven immune cell dysfunction in the development of lung disease in AATD. The authors discuss the role of AAT as a key modulator of TNF-α signaling firstly in the setting of AATD and secondly in other conditions where AAT augmentation therapy has potential utility as a novel therapy.

Adult liver disorders caused by inborn errors of metabolism: review and update

Inborn errors of metabolism (IEMs) are a group of genetic diseases that have protean clinical manifestations and can involve several organ systems. The age of onset is highly variable but IEMs afflict mostly the pediatric population. However, in the past decades, the advancement in management and new therapeutic approaches have led to the improvement in IEM patient care. As a result, many patients with IEMs are surviving into adulthood and developing their own set of complications. In addition, some IEMs will present in adulthood. It is important for internists to have the knowledge and be familiar with these conditions because it is predicted that more and more adult patients with IEMs will need continuity of care in the near future. The review will focus on Wilson disease, alpha-1 antitrypsin deficiency, citrin deficiency, and HFE-associated hemochromatosis which are typically found in the adult population. Clinical manifestations and pathophysiology, particularly those that relate to hepatic disease as well as diagnosis and management will be discussed in detail.

Identification and characterisation of eight novel SERPINA1 Null mutations

Background

Alpha-1 antitrypsin (AAT) is the most abundant circulating antiprotease and is a member of the serine protease inhibitor (SERPIN) superfamily. The gene encoding AAT is the highly polymorphic SERPINA1 gene, found at 14q32.1. Mutations in the SERPINA1 gene can lead to AAT deficiency (AATD) which is associated with a substantially increased risk of lung and liver disease. The most common pathogenic AAT variant is Z (Glu342Lys) which causes AAT to misfold and polymerise within hepatocytes and other AAT-producing cells. A group of rare mutations causing AATD, termed Null or Q0, are characterised by a complete absence of AAT in the plasma. While ultra rare, these mutations confer a particularly high risk of emphysema.

Methods

We performed the determination of AAT serum levels by a rate immune nephelometric method or by immune turbidimetry. The phenotype was determined by isoelectric focusing analysis on agarose gel with specific immunological detection. DNA was isolated from whole peripheral blood or dried blood spot (DBS) samples using a commercial extraction kit. The new mutations were identified by sequencing all coding exons (II-V) of the SERPINA1 gene.

Results

We have found eight previously unidentified SERPINA1 Null mutations, named: Q0_cork, Q0_perugia, Q0_brescia, Q0_torino, Q0_cosenza, Q0_pordenone, Q0_lampedusa, and Q0_dublin . Analysis of clinical characteristics revealed evidence of the recurrence of lung symptoms (dyspnoea, cough) and lung diseases (emphysema, asthma, chronic bronchitis) in M/Null subjects, over 45 years-old, irrespective of smoking.

Conclusions

We have added eight more mutations to the list of SERPINA1 Null alleles. This study underlines that the laboratory diagnosis of AATD is not just a matter of degree, because the precise determination of the deficiency and Null alleles carried by an AATD individual may help to evaluate the risk for the lung disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-014-0172-y) contains supplementary material, which is available to authorized users.

α1-Antitrypsin deficiency in a patient diagnosed with granulomatosis with polyangiitis

Granulomatosis with polyangiitis is a rare type of vasculitis that affects small-sized and medium-sized vessels. Any organ system can become affected, but it most commonly affects the upper airways, lungs and kidneys. The α1-antitrypsin deficiency is another rare disease that involves a genetic deficiency in the enzyme antitrypsin, which is produced in the liver and protects the lung against proteinases. The simultaneous occurrence of these two diseases is very rare and has been described. We present a case of granulomatosis with polyangiitis limited to the upper airways, and α1-antitrypsin deficiency occurring in the same patient. The patient presented with recurrent upper airway infections. The patient was treated with steroids and azathioprine which prevented recurrence of symptoms. High clinical suspicion of the concomitant occurrence of α1-antitrypsin deficiency in patients with vasculitis is essential to provide patients with adequate screening and treatment.

Alpha-1 antitrypsin: a potent anti-inflammatory and potential novel therapeutic agent

Alpha-1 antitrypsin (AAT) has long been thought of as an important anti-protease in the lung where it is known to decrease the destructive effects of major proteases such as neutrophil elastase. In recent years, the perception of this protein in this simple one dimensional capacity as an anti-protease has evolved and it is now recognised that AAT has significant anti-inflammatory properties affecting a wide range of inflammatory cells, leading to its potential therapeutic use in a number of important diseases. This present review aims to discuss the described anti-inflammatory actions of AAT in modulating key immune cell functions, delineate known signalling pathways and specifically to identify the models of disease in which AAT has been shown to be effective as a therapy.

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

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

The prevalence of alpha-1 antitrypsin deficiency in Ireland

Background

Alpha-1 antitrypsin deficiency (AATD) results from mutations in the SERPINA1 gene and classically presents with early-onset emphysema and liver disease. The most common mutation presenting with clinical evidence is the Z mutation, while the S mutation is associated with a milder plasma deficiency. AATD is an under-diagnosed condition and the World Health Organisation recommends targeted detection programmes for AATD in patients with chronic obstructive pulmonary disease (COPD), non-responsive asthma, cryptogenic liver disease and first degree relatives of known AATD patients.

Methods

We present data from the first 3,000 individuals screened following ATS/ERS guidelines as part of the Irish National Targeted Detection Programme (INTDP). We also investigated a DNA collection of 1,100 individuals randomly sampled from the general population. Serum and DNA was collected from both groups and mutations in the SERPINA1 gene detected by phenotyping or genotyping.

Results

The Irish National Targeted Detection Programme identified 42 ZZ, 44 SZ, 14 SS, 430 MZ, 263 MS, 20 IX and 2 rare mutations. Analysis of 1,100 randomly selected individuals identified 113 MS, 46 MZ, 2 SS and 2 SZ genotypes.

Conclusion

Our findings demonstrate that AATD in Ireland is more prevalent than previously estimated with Z and S allele frequencies among the highest in the world. Furthermore, our targeted detection programme enriched the population of those carrying the Z but not the S allele, suggesting the Z allele is more important in the pathogenesis of those conditions targeted by the detection programme.

AAT as a diagnostic tool

Serum alpha-1-antitrypsin (AAT) concentration can be affected by both inflammatory and non-inflammatory conditions. This paper characterizes the nature of AAT in physiology and pathologic deficiency and increasing states. The relationships between the AAT concentration in different clinical materials (serum, urine, faeces) and various diseases connected with different organs were analyzed.

Intestinal Wegener's granulomatosis in a patient with severe alpha-1-antitrypsin deficiency resulting from a unique combination of two deficiency alleles (PiZ and PiMProcida)

Alpha-1-antitripsyn neutralizes the tissue damaging effects of proteases. Alpha-1-antitripsyn deficiency manifests with necrotizing vasculitis. Wegener's granulomatosis is a systemic necrotizing vasculitis that uncommonly affects the gut. The molecular genetics of patients with Wegener's granulomatosis of the gastrointestinal tract have never been characterized. A 63-year-old man with emphysema was admitted with a fever of unknown origin. Initially, this fever was linked to ileocolic Crohn's disease and later attributed to antineutrophil cytoplasm antibody-positive systemic vasculitis. Genetic analysis revealed that the alpha-1-antitripsyn deficiency was due to a previously unreported compound heterozygosity for two mutations (PiZ and PiMProcida). Our findings appear to support the concept that severe alpha-1-antitripsyn deficiency is implicated in the pathogenesis of the Crohn's disease-like milder intestinal manifestations belonging to the spectrum of Wegener's granulomatosis.