Efficacy of alpha1-antitrypsin augmentation therapy in conditions other than pulmonary emphysema

Immunological and homeostatic pathways of alpha -1 antitrypsin: a new therapeutic potential

α -1 antitrypsin (A1AT) is a 52 kDa acute-phase glycoprotein belonging to the serine protease inhibitor superfamily (SERPIN). It is primarily synthesized by hepatocytes and to a lesser extent by monocytes, macrophages, intestinal epithelial cells, and bronchial epithelial cells. A1AT is encoded by SERPINA1 locus, also known as PI locus, highly polymorphic with at least 100 allelic variants described and responsible for different A1AT serum levels and function. A1AT inhibits a variety of serine proteinases, but its main target is represented by Neutrophil Elastase (NE). However, recent attention has been directed towards its immune-regulatory and homeostatic activities. A1AT exerts immune-regulatory effects on different cell types involved in innate and adaptive immunity. Additionally, it plays a role in metal and lipid metabolism, contributing to homeostasis. An adequate comprehension of these mechanisms could support the use of A1AT augmentation therapy in many disorders characterized by a chronic immune response. The aim of this review is to provide an up-to-date understanding of the molecular mechanisms and regulatory pathways responsible for immune-regulatory and homeostatic activities of A1AT. This knowledge aims to support the use of A1AT in therapeutic applications. Furthermore, the review summarizes the current state of knowledge regarding the application of A1AT in clinical and laboratory settings human and animal models.

α1-Antitrypsin deficiency associated with increased risk of heart failure

Background

Individuals with α1-antitrypsin deficiency have increased elastase activity resulting in continuous degradation of elastin and early onset of COPD. Increased elastase activity may also affect elastic properties of the heart, which may impact risk of heart failure. We tested the hypothesis that α1-antitrypsin deficiency is associated with increased risk of heart failure in two large populations.

Methods

In a nationwide nested study of 2209 patients with α1-antitrypsin deficiency and 21 869 controls without α1-antitrypsin deficiency matched on age, sex and municipality, we recorded admissions and deaths due to heart failure during a median follow-up of 62 years. We also studied a population-based cohort of another 102 481 individuals from the Copenhagen General Population Study including 187 patients from the Danish α1-Antitrypsin Deficiency Registry, all with genetically confirmed α1-antitrypsin deficiency.

Results

Individuals with versus without α1-antitrypsin deficiency had increased risk of heart failure hospitalisation in the nationwide cohort (adjusted hazard ratio 2.64, 95% CI 2.25-3.10) and in the population-based cohort (1.77, 95% CI 1.14-2.74). Nationwide, these hazard ratios were highest in those without myocardial infarction (3.24, 95% CI 2.70-3.90), without aortic valve stenosis (2.80, 95% CI 2.38-3.29), without hypertension (3.44, 95% CI 2.81-4.22), without atrial fibrillation (3.33, 95% CI 2.75-4.04) and without any of these four diseases (6.00, 95% CI 4.60-7.82). Hazard ratios for heart failure-specific mortality in individuals with versus without α1-antitrypsin deficiency were 2.28 (95% CI 1.57-3.32) in the nationwide cohort and 3.35 (95% CI 1.04-10.74) in the population-based cohort.

Conclusion

Individuals with α1-antitrypsin deficiency have increased risk of heart failure hospitalisation and heart failure-specific mortality in the Danish population.

Diagnostic Approach and Pathophysiological Mechanisms of Anemia in Chronic Liver Disease—An Overview

Hematological abnormalities are frequently linked to chronic liver disease of any etiology. About 75% of patients with advanced chronic liver disease experience anemia. The causes of anemia are complex and multifactorial, particularly in cirrhotic patients. Acute and long-term blood loss from the upper gastrointestinal tract, malnutrition, an enlarged spleen brought on by portal hypertension, hemolysis, and coagulation issues are the main causes of anemia. Alcohol, a common cause of chronic liver disease, determines anemia through direct toxicity on the bone marrow, with the suppression of hematopoiesis, through vitamin B6, B12, and folate deficiency due to low intake and malabsorption. In patients with chronic hepatitis C virus infection, antiviral drugs such as pegylated interferon and ribavirin can also cause significant anemia. The use of interferon has been linked to bone marrow toxicity, and hemolytic anemia brought on by ribavirin is a well-known dose-dependent side effect. Within six months of the infection with hepatitis B, hepatitis C, and Epstein–Barr viruses, aplastic anemia associated with hepatitis is seen. This anemia is characterized by pancytopenia brought on by hypocellular bone marrow. Esophageal varices, portal hypertensive gastropathy, and gastric antral vascular ectasia can all cause acute and chronic blood loss. These conditions can progress to iron deficiency anemia, microcytic anemia, and hypochromic anemia. Another common hematologic abnormality in liver cirrhosis is macrocytosis, with multifactorial causes. Vitamin B12 and folate deficiency are frequent in liver cirrhosis, especially of alcoholic etiology, due to increased intestinal permeability, dysbiosis, and malnutrition. Many chronic liver diseases, like viral and autoimmune hepatitis, have a chronic inflammatory substrate. Proinflammatory cytokines, including tumor necrosis factor and interleukin 1, 6, and 10, are the main factors that diminish iron availability in progenitor erythrocytes and subsequent erythropoiesis, leading to the development of chronic inflammatory, normochromic, normocytic anemia.

Negative regulation of ATP-induced inflammasome activation and cytokine secretion by acute-phase proteins: A mini review

The expression of the acute-phase reactants C-reactive protein (CRP), α1-antitrypsin (AAT), and secretory leukocyte protease inhibitor (SLPI), is induced in response to inflammation by pro-inflammatory mediators, including interleukin-1β. It is conceivable that acute-phase proteins exert protective functions, when the integrity of an organism is challenged by pathogens or trauma, which result in uncontrolled release of endogenous damage-associated molecular patterns like Toll-like receptor agonists and ATP. Acute-phase proteins can enhance or down-modulate immunity against infections or protect the host against damage caused by over-shooting effector functions of the immune system. CRP is mainly regarded as a pro-inflammatory opsonizing agent that binds to bacteria and damaged host cells thereby contributing to their inactivation and elimination. AAT and SLPI are well known for their anti-protease activity, which protects the lung extracellular matrix against degradation by proteases that are released by activated neutrophil granulocytes. In addition, there is growing evidence, that CRP, AAT, and SLPI can control the biosynthesis, maturation, and secretion of pro-inflammatory cytokines. The purpose of this narrative mini review is to summarize these anti-inflammatory functions with a focus on the negative control of the ATP-induced, inflammasome-dependent secretion of interleukin-1β by monocytes. CRP-, AAT- and SLPI-mediated control of interleukin-1β release involves the activation of unconventional nicotinic acetylcholine receptors that inhibits the ionotropic function of the ATP receptor P2X7. Apart from other functions, CRP, AAT, and SLPI seem to be central elements of systemic negative feedback loops that protect the host against systemic hyperinflammation, barrier dysfunction, and death by multiple organ damage.

Alpha-1 antitrypsin in autoimmune diseases: Roles and therapeutic prospects

Alpha-1 antitrypsin (A1AT) is a protease inhibitor in the serum. Its primary function is to inhibit the activity of a series of proteases, including proteinase 3, neutrophil elastase, metalloproteases, and cysteine-aspartate proteases. In addition, A1AT also has anti-inflammatory, anti-apoptotic, anti-oxidative stress, anti-viral, and anti-bacterial activities and plays essential roles in the regulation of tissue repair and lymphocyte differentiation and activation. The overactivation of the immune system characterizes the pathogenesis of autoimmune diseases. A1AT treatment shows beneficial effects on patients and animal models with autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. This review summarizes the functions and therapeutic prospects of A1AT in autoimmune diseases.

Ubiquitination of ADRα1d/SerpinA1 complex stimulates hypoxia to induce gastric tumorigenesis with a combination of Helicobacter pylori and chronic stress through IL-1α

BACKGROUND

Helicobacter pylori (H. pylori) has been recognized as the class I carcinogen of gastric cancer and several studies have demonstrated that chronic stress may accelerate gastric cancer progression. However, the evidence is not sufficient.

METHODS

Here, we developed a mouse model that combined H. pylori infection with chronic stress. Gastric inflammation promotes gastric tumor development progression. To evaluate the number of pro-inflammatory cells through observing the numbers of activated macrophages and neutrophils in mice gastric tumors compared with untreated mice or only treated with one factor. ADRα1d /SerpinA1 expression and localization were assessed under stress conditions and H. pylori infection, and evaluated by analyzing IL-1α, CD8, platelet, and RBC status using α- or β- blockers against gastritis to prevent gastric cancer.

RESULTS

Further mechanism study showed that stress hormones increase the number of CD8⁺ lymphocytes by activating ADRβ2 receptors, leading to IL-1α secretion and tumorigenicity. Gastric carcinogenesis also involves gastric muscle contraction mediated through ADRα1d/Serpina1 interaction. Specifically, we showed that the ADRα1d/SerpinA1 complex increases glucose uptake and the development of hypoxia conditions. These responses promote platelet aggregation and muscle contraction. In turn, gastric cancer cells increase lactate production and promote gastric cell proliferation through Muc-13 and IL-1α stimulation.

CONCLUSION

H. pylori infection in combination with chronic stress can lead to gastric cancer, and the synergistic effects of cytokine production (i.e. IL-1α), T lymphocyte dysfunction contributes to gastric carcinogenesis which will offer treatment opportunities for stress-associated gastric cancer and provide new strategies for the prevention and treatment of gastric cancer in clinics.

Application of alpha1-antitrypsin in a rat model of veno-arterial extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) is a life-saving intervention for patients suffering from respiratory or cardiac failure. The ECMO-associated morbidity and mortality depends to a large extent on the underlying disease and is often related to systemic inflammation, consecutive immune paralysis and sepsis. Here we tested the hypothesis that human α1-antitrypsin (SERPINA1) due to its anti-protease and anti-inflammatory functions may attenuate ECMO-induced inflammation. We specifically aimed to test whether intravenous treatment with α1-antitrypsin reduces the release of cytokines in response to 2 h of experimental ECMO. Adult rats were intravenously infused with α1-antitrypsin immediately before starting veno-arterial ECMO. We measured selected pro- and anti-inflammatory cytokines and found, that systemic levels of tumor necrosis factor-α, interleukin-6 and interleukin-10 increase during experimental ECMO. As tachycardia and hypertension developed in response to α1-antitrypsin, a single additional bolus of fentanyl and midazolam was given. Treatment with α1-antitrypsin and higher sedative doses reduced all cytokine levels investigated. We suggest that α1-antitrypsin might have the potential to protect against both ECMO-induced systemic inflammation and immune paralysis. More studies are needed to corroborate our findings, to clarify the mechanisms by which α1-antitrypsin inhibits cytokine release in vivo and to explore the potential application of α1-antitrypsin in clinical ECMO.

Alpha-1 antitrypsin deficiency and recombinant protein sources with focus on plant sources: Updates, challenges and perspectives

Alpha-1 antitrypsin deficiency (A1ATD) is an autosomal recessive disease characterized by low plasma levels of A1AT, a serine protease inhibitor representing the most abundant circulating antiprotease normally present at plasma levels of 1-2 g/L. The dominant clinical manifestations include predispositions to early onset emphysema due to protease/antiprotease imbalance in distal lung parenchyma and liver disease largely due to unsecreted polymerized accumulations of misfolded mutant A1AT within the endoplasmic reticulum of hepatocytes. Since 1987, the only FDA licensed specific therapy for the emphysema component has been infusions of A1AT purified from pooled human plasma at the 2020 cost of up to US $200,000/year with the risk of intermittent shortages. In the past three decades various, potentially less expensive, recombinant forms of human A1AT have reached early stages of development, one of which is just reaching the stage of human clinical trials. The focus of this review is to update strategies for the treatment of the pulmonary component of A1ATD with some focus on perspectives for therapeutic production and regulatory approval of a recombinant product from plants. We review other competitive technologies for treating the lung disease manifestations of A1ATD, highlight strategies for the generation of data potentially helpful for securing FDA Investigational New Drug (IND) approval and present challenges in the selection of clinical trial strategies required for FDA licensing of a New Drug Approval (NDA) for this disease.

Proteomics in Deaths by Drowning: Diagnostic Efficacy of Apolipoprotein A1 and α-1Antitrypsin, Pilot Study

Drowning is one of the leading causes of death worldwide. The pathophysiology of drowning is complex and, sometimes, interpretation of the circumstances of death in the autopsy becomes the main source of information in its diagnosis. New advances in medical research, such as proteomics, especially in forensic pathology, are still in the development. We proposed to investigate the application of Mass Spectrometry-based technologies, to identify differentially expressed proteins that may act as potential biomarkers in the postmortem diagnosis of drowning. We performed a pilot proteomic experiment with the inclusion of two drowned and two control forensic cases. After applying restrictive parameters, we identified apolipoprotein A1 (ApoA1) and α-1 antitrypsin as differentially expressed between the two diagnostic groups. A validation experiment, with the determination of both proteins in 25 forensic cases (16 drowned and 9 controls) was performed, and we corroborated ApoA1 higher values in the drowning group, whereas α-1 antitrypsin showed lower levels. After adjusting by confounder factors, both remained as predictive independent factors for diagnosis of drowning (p = 0.010 and p = 0.022, respectively). We constructed ROC curves for biomarkers' levels attending at the origin of death and established an ApoA1 cut-off point of 100 mg/dL. Correct classification based on the diagnosis criteria was reached for 73.9% of the cases in a discriminant analysis. We propose apolipoprotein A1 (with our cutoff value for correct classification) and α-1 antitrypsin as valuable biomarkers of drowning. Our study, based on forensic cases, reveals our proteomic approach as a new complementary tool in the forensic diagnosis of drowning and, perhaps, in clinical future implications in drowned patients. However, this is a pilot approach, and future studies are necessary to consolidate our promising preliminary data.

Alpha-1 Antitrypsin Substitution for Extrapulmonary Conditions in Alpha-1 Antitrypsin Deficient Patients

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder which most commonly manifests as pulmonary emphysema. Accordingly, alpha-1 antitrypsin (AAT) augmentation therapy aims to reduce the progression of emphysema, as achieved by life-long weekly slow-drip infusions of plasma-derived affinity-purified human AAT. However, not all AATD patients will receive this therapy, due to either lack of medical coverage or low patient compliance. To circumvent these limitations, attempts are being made to develop lung-directed therapies, including inhaled AAT and locally-delivered AAT gene therapy. Lung transplantation is also an ultimate therapy option. Although less common, AATD patients also present with disease manifestations that extend beyond the lung, including vasculitis, diabetes and panniculitis, and appear to experience longer and more frequent hospitalization times and more frequent pneumonia bouts. In the past decade, new mechanism-based clinical indications for AAT therapy have surfaced, depicting a safe, anti-inflammatory, immunomodulatory and tissue-protective agent. Introduced to non-AATD individuals, AAT appears to provide relief from steroid-refractory graft-versus-host disease, from bacterial infections in cystic fibrosis and from autoimmune diabetes; preclinical studies show benefit also in multiple sclerosis, ulcerative colitis, rheumatoid arthritis, acute myocardial infarction and stroke, as well as ischemia-reperfusion injury and aberrant wound healing processes. While the current augmentation therapy is targeted towards treatment of emphysema, it is suggested that AATD patients may benefit from AAT augmentation therapy geared towards extrapulmonary pathologies as well. Thus, development of mechanism-based, context-specific AAT augmentation therapy protocols is encouraged. In the current review, we will discuss extrapulmonary manifestations of AATD and the potential of AAT augmentation therapy for these conditions.

SERPINA1 mRNA as a Treatment for Alpha-1 Antitrypsin Deficiency

Alpha-1-antitrypsin (AAT) deficiency is a genetic disorder that produces inactive/defective AAT due to mutations in the SERPINA1 gene encoding AAT. This disease is associated with decreased activity of AAT in the lungs and deposition of excessive defective AAT protein in the liver. Currently there is no specific treatment for liver disease associated with AAT deficiency. AAT lung disease is often treated with one of several serum protein replacement products; however, long-term studies of the effectiveness of SerpinA1 replacement therapy are not available, and it does not reduce liver damage in AAT deficiency. mRNA therapy could potentially target both the liver and lungs of AAT deficient patients. AAT patient fibroblasts and AAT patient fibroblast-derived hepatocytes were transfected with SERPINA1-encoding mRNA and cell culture media were tested for SerpinA1 expression. Our data demonstrates increased SerpinA1 protein in culture media from treated AAT patient fibroblasts and AAT patient fibroblast-derived hepatocytes. In vivo studies in wild type mice demonstrate SERPINA1 mRNA biodistribution in liver and lungs, as well as SerpinA1 protein expression in these two target organs which are critically affected in AAT deficiency. Taken together, our data suggests that SerpinA1 mRNA therapy has the potential to benefit patients suffering from AAT deficiency.

Alpha-1 Antitrypsin Inhibits ATP-Mediated Release of Interleukin-1β via CD36 and Nicotinic Acetylcholine Receptors

While interleukin (IL)-1β is a potent pro-inflammatory cytokine involved in host defense, high levels can cause life-threatening sterile inflammation including systemic inflammatory response syndrome. Hence, the control of IL-1β secretion is of outstanding biomedical importance. In response to a first inflammatory stimulus such as lipopolysaccharide, pro-IL-1β is synthesized as a cytoplasmic inactive pro-form. Extracellular ATP originating from injured cells is a prototypical second signal for inflammasome-dependent maturation and release of IL-1β. The human anti-protease alpha-1 antitrypsin (AAT) and IL-1β regulate each other via mechanisms that are only partially understood. Here, we demonstrate that physiological concentrations of AAT efficiently inhibit ATP-induced release of IL-1β from primary human blood mononuclear cells, monocytic U937 cells, and rat lung tissue, whereas ATP-independent IL-1β release is not impaired. Both, native and oxidized AAT are active, suggesting that the inhibition of IL-1β release is independent of the anti-elastase activity of AAT. Signaling of AAT in monocytic cells involves the lipid scavenger receptor CD36, calcium-independent phospholipase A2β, and the release of a small soluble mediator. This mediator leads to the activation of nicotinic acetylcholine receptors, which efficiently inhibit ATP-induced P2X7 receptor activation and inflammasome assembly. We suggest that AAT controls ATP-induced IL-1β release from human mononuclear blood cells by a novel triple-membrane-passing signaling pathway. This pathway may have clinical implications for the prevention of sterile pulmonary and systemic inflammation.

The important role of primary care providers in the detection of alpha-1 antitrypsin deficiency

OBJECTIVE

Alpha-1 antitrypsin deficiency (AATD) is an underrecognized genetic disorder that can cause chronic obstructive pulmonary disease (COPD) and liver cirrhosis, two clinical conditions commonly seen by primary care physicians. AATD is estimated to affect 1/4000-1/5000 people in the United States and 1-2% of all COPD cases.

METHODS

PubMed was searched for relevant articles using AAT/AATD-related terms.

RESULTS

Unfortunately, <10% of symptomatic individuals have been properly diagnosed primarily due to the underdiagnosis of COPD and the lack of awareness of AATD as a possible underlying cause. Because primary care providers are most likely to be the first to encounter symptomatic individuals, their role in the identification and early diagnosis of AATD patients is instrumental, particularly since therapy to slow lung disease progression is available. The diagnosis of AATD is laboratory-based rather than clinical. Testing for AATD should be part of the reflex testing that follows any COPD diagnosis or unexplained liver disease and can be performed by determining the AAT phenotype or genotype along with serum AAT levels. Both nonpharmacological and pharmacological approaches are recommended for treatment of lung disease, including smoking cessation, bronchodilators or supplemental oxygen as needed. Specific augmentation of AAT levels with regular purified AAT infusions has been found to slow lung function decline and emphysema progression in patients with moderate airflow obstruction and severely low serum AAT levels.

CONCLUSIONS

Improving primary care provider awareness and promoting regular reflex testing all COPD patients for AATD may significantly improve the care of COPD patients.

Clinical utility of alpha-1 proteinase inhibitor in the management of adult patients with severe alpha-1 antitrypsin deficiency: a review of the current literature

Alpha-1 antitrypsin (AAT) functions primarily to inhibit neutrophil elastase, and its deficiency predisposes individuals to the development of chronic obstructive pulmonary disease (COPD). The putative protective serum concentration is generally considered to be above a threshold of 11 μM/L, and therapeutic augmentation of AAT above this value is believed to retard the progression of emphysema. Several AAT preparations, all derived from human donor plasma, have been commercialized since approval by the US Food and Drug Administration (FDA) in 1987. Biochemical efficacy has been demonstrated by augmentation of pulmonary antiprotease activity, but demonstration of clinical efficacy in randomized, placebo-controlled trials has been hampered by the practical difficulties of performing conventional studies in a rare disease with a relatively long natural history. Computed tomography has been applied to measure lung density as a more specific and sensitive surrogate outcome measure of emphysema than physiologic indices, such as forced expiratory volume in 1 second, and studies consistently show a therapeutic reduction in the rate of lung density decline. However, convincing evidence of benefit using traditional clinical measures remains elusive. Intravenous administration of AAT at a dose of 60 mg/kg/week is the commonest regime in use and has well-documented safety and tolerability. International and national guidelines on the management of AAT deficiency recommend intravenous augmentation therapy to supplement optimized usual COPD treatment in patients with severe deficiency and evidence of lung function impairment.

Elastase and matrix metalloproteinase activities are associated with pulmonary vascular disease in the nitrofen rat model of congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Pulmonary vascular disease (PVD) is a leading cause of congenital diaphragmatic hernia (CDH) mortality. Progression of PVD involves extracellular matrix remodeling by elastases and matrix metalloproteinases (MMP), concomitant with proliferation of smooth muscle cells in a growth factor-enriched environment. Blockade of this pathway reversed primary pulmonary hypertension and improved survival. This study was designed to determine whether a similar pathway is induced in PVD secondary to CDH.

METHODS

Fetal rats exposed to nitrofen at gestational day 9 developed left-sided CDH and were compared at term to their non-CDH littermates by assessing histologic and biochemical features of PVD.

RESULTS

Rats with CDH displayed right ventricle hypertrophy, increased pulmonary artery medial wall thickness and muscularization, and decreased lumen size. As revealed by in situ zymography and immunohistochemistry, this was associated with an induction of elastolytic and MMP activities as well as an elevation of epidermal growth factor and osteopontin levels in the diseased lung vasculature.

CONCLUSIONS

CDH-associated PVD involves an induction of elastase and MMP activities and increased osteopontin deposition in an epidermal growth factor-rich environment. Inhibition of this pathway may thus represent a novel therapeutic approach for the treatment of CDH-associated PVD.

LEVEL OF EVIDENCE

Level I (Basic Science Study).

Alpha-1-antitrypsin deficiency: Genetic variations, clinical manifestations and therapeutic interventions

Alpha-1-antitrypsin (AAT) is an acute phase secretory glycoprotein that inhibits neutrophil proteases like elastase and is considered as the archetype of a family of structurally related serine-protease inhibitors termed serpins. Serum AAT predominantly originates from liver and increases three to five fold during host response to tissue injury and inflammation. The AAT deficiency is unique among the protein-misfolding diseases in that it causes target organ injury by both loss-of-function and gain-of-toxic function mechanisms. Lack of its antiprotease activity is associated with premature development of pulmonary emphysema and loss-of-function due to accumulation of resultant aggregates in chronic obstructive pulmonary disease (COPD). This' in turn' markedly reduces the amount of AAT that is available to protect lungs against proteolytic attack by the enzyme neutrophil elastase. The coalescence of AAT deficiency, its reduced efficacy, and cigarette smoking or poor ventilation conditions have devastating effect on lung function. On the other hand, the accumulation of retained mutant proteins in the endoplasmic reticulum of hepatocytes in a polymerized form rather than secreted into the blood in its monomeric form is associated with chronic liver disease and predisposition to hepatocellular carcinoma (HCC) by gain- of- toxic function. Liver injury resulting from this gain-of-toxic function mechanism in which mutant AAT retained in the ER initiates a series of pathologic events, eventually culminating at liver cirrhosis and HCC. Here in this review, we underline the structural, genetic, polymorphic, biochemical and pathological advances made in the field of AAT deficiency and further comprehensively emphasize on the therapeutic interventions available for the patient.

Recent advances in understanding and treating COPD related to α1-antitrypsin deficiency

INTRODUCTION

Alpha-1-antitrypsin deficiency (AATD) is an orphan disease that predisposes individuals to COPD and liver disease. The following is a comprehensive review of AATD from epidemiology to treatment for physicians who treat COPD or asthma. Areas covered: In this comprehensive review of alpha-1-antitrypsin deficiency, we describe the historical perspective, genetics, epidemiology, clinical presentation and symptoms, screening and diagnosis, and treatments of the condition. Expert commentary: The two most important directions for advancing the understanding of AATD involve improving detection of the condition, especially in asymptomatic patients, and advancing knowledge of treatments directed specifically at AATD-related conditions. With regard to treatment for AATD-related conditions, research must continue to explore the implications and importance of augmentation therapy as well as consider new implementations that may prove more successful taking into consideration not only factors of pulmonary function and liver health, but also product availability and financial viability.

Rare case of eosinophilic granulomatosis with polyangiitis in two patients with α-1-antitrypsin deficiency (PiSZ)

We present two cases of eosinophilic granulomatosis with polyangiitis occurring with α-1-antitrypsin deficiency, both PiSZ phenotype. The simultaneous occurrence of these two conditions has seldom been described in the literature, despite evidence of an association between α-1-antitrypsin deficiency and other forms of vasculitis. Both patients had pulmonary involvement and reported intermittent exacerbations of vasculitic symptoms. Both patients were managed on low-dose oral steroids and azathioprine remaining well with occasional exacerbations. It is important to consider whether there is an association between eosinophilic granulomatosis with polyangiitis and α-1-antitrypsin deficiency, as this may lead to more severe pulmonary symptoms during exacerbations. If a genetic association between the two conditions is found, clinicians should be aware of the possible need to screen for α-1-antitrypsin deficiency in appropriate patients.

Augmentation therapy of alpha-1 antitrypsin deficiency associated emphysema

INTRODUCTION

Alpha-1 antitrypsin, secreted by the liver, inhibits neutrophil elastase. Its deficiency favours the development of emphysema. Restoring a "protective" serum level in deficient patients should make it possible to inhibit the development of emphysema.

STATE OF THE ART

Human plasma-derived alpha-1 antitrypsin is a blood-derived drug sold in France under the name Alfalastin(®). The recommended posology is an I.V. administration of 60 mg/kg once a week. Human plasma-derived alpha-1 antitrypsin restores anti-elastase protection in the lower lung and prevents experimental emphysema induced by the elastasis of human neutrophils in hamster. The low number of patients with alpha-1 antitrypsin deficiency is one of the difficulties to perform sufficiently powerful randomised studies. However, randomised studies have reported the efficacy of human plasma-derived alpha-1 antitrypsin perfusions on mortality, FEV1 decline and the frequency of exacerbations. Randomised control trials have demonstrated the efficacy of human plasma-derived alpha-1 antitrypsin perfusions on the loss of lung density assessed by CT scan.

CONCLUSION

Augmentation therapy is simple in its conception and implementation, but it is expensive. However, there are currently no other solutions.

Acute-phase protein α1-anti-trypsin: diverting injurious innate and adaptive immune responses from non-authentic threats

One would assume that the anti-inflammatory activity of α1-anti-trypsin (AAT) is the result of inhibiting neutrophil enzymes. However, AAT exhibits tolerogenic activities that are difficult to explain by serine-protease inhibition or by reduced inflammatory parameters. Targets outside the serine-protease family have been identified, supporting the notion that elastase inhibition, the only functional factory release criteria for clinical-grade AAT, is over-emphasized. Non-obvious developments in the understanding of AAT biology disqualify it from being a straightforward anti-inflammatory agent: AAT does not block dendritic cell activities, nor does it promote viral and tumour susceptibilities, stunt B lymphocyte responses or render treated patients susceptible to infections; accordingly, outcomes of elevated AAT do not overlap those attained by immunosuppression. Aside from the acute-phase response, AAT rises during the third trimester of pregnancy and also in advanced age. At the molecular level, AAT docks onto cholesterol-rich lipid-rafts and circulating lipid particles, directly binds interleukin (IL)-8, ADAM metallopeptidase domain 17 (ADAM17) and danger-associated molecular pattern (DAMP) molecules, and its activity is lost to smoke, high glucose levels and bacterial proteases, introducing a novel entity - 'relative AAT deficiency'. Unlike immunosuppression, AAT appears to help the immune system to distinguish between desired responses against authentic threats, and unwanted responses fuelled by a positive feedback loop perpetuated by, and at the expense of, inflamed injured innocent bystander cells. With a remarkable clinical safety record, AAT treatment is currently tested in clinical trials for its potential benefit in a variety of categorically distinct pathologies that share at least one common driving force: cell injury.

High-density lipoproteins potentiate α1-antitrypsin therapy in elastase-induced pulmonary emphysema

Several studies report that high-density lipoproteins (HDLs) can carry α1-antitrypsin (AAT; an elastase inhibitor). We aimed to determine whether injection of exogenous HDL, enriched or not in AAT, may have protective effects against pulmonary emphysema. After tracheal instillation of saline or elastase, mice were randomly treated intravenously with saline, human plasma HDL (75 mg apolipoprotein A1/kg), HDL-AAT (75 mg apolipoprotein A1-3.75 mg AAT/kg), or AAT alone (3.75 mg/kg) at 2, 24, 48, and 72 hours. We have shown that HDL-AAT reached the lung and prevented the development of pulmonary emphysema by 59.3% at 3 weeks (alveoli mean chord length, 22.9 ± 2.8 μm versus 30.7 ± 4.5 μm; P < 0.001), whereas injection of HDL or AAT alone only showed a moderate, nonsignificant protective effect (28.2 ± 4.2 μm versus 30.7 ± 5 μm [P = 0.23] and 27.3 ± 5.66 μm versus 30.71 ± 4.96 μm [P = 0.18], respectively). Indeed, protection by HDL-AAT was significantly higher than that observed with HDL or AAT (P = 0.006 and P = 0.048, respectively). This protective effect was associated (at 6, 24, and 72 h) with: (1) a reduction in neutrophil and macrophage number in the bronchoalveolar lavage fluid; (2) decreased concentrations of IL-6, monocyte chemoattractant protein-1, and TNF-α in both bronchoalveolar lavage fluid and plasma; (3) a reduction in matrix metalloproteinase-2 and matrix metalloproteinase-9 activities; and (4) a reduction in the degradation of fibronectin, a marker of tissue damage. In addition, HDL-AAT reduced acute cigarette smoke-induced inflammatory response. Intravenous HDL-AAT treatment afforded a better protection against elastase-induced pulmonary emphysema than AAT alone, and may represent a significant development for the management of emphysema associated with AAT deficiency.

Role of alpha-1 antitrypsin in human health and disease

Alpha-1 antitrypsin (AAT) deficiency is an under-recognized hereditary disorder associated with the premature onset of chronic obstructive pulmonary disease, liver cirrhosis in children and adults, and less frequently, relapsing panniculitis, systemic vasculitis and other inflammatory, autoimmune and neoplastic diseases. Severe AAT deficiency mainly affects Caucasian individuals and has its highest prevalence (1 : 2000-1 : 5000 individuals) in Northern, Western and Central Europe. In the USA and Canada, the prevalence is 1: 5000-10 000. Prevalence is five times lower in Latin American countries and is rare or nonexistent in African and Asian individuals. The key to successful diagnosis is by measuring serum AAT, followed by the determination of the phenotype or genotype if low concentrations are found. Case detection allows implementation of genetic counselling and, in selected cases, the application of augmentation therapy. Over the past decade, it has been demonstrated that AAT is a broad-spectrum anti-inflammatory, immunomodulatory, anti-infective and tissue-repair molecule. These new capacities are promoting an increasing number of clinical studies, new pharmacological formulations, new patent applications and the search for alternative sources of AAT (including transgenic and recombinant AAT) to meet the expected demand for treating a large number of diseases, inside and outside the context of AAT deficiency.

Alpha-1 antitrypsin deficiency: new developments in augmentation and other therapies

Alpha 1 antitrypsin deficiency (AATD) is a rare cause of chronic obstructive pulmonary disease. The lung disease is thought to be caused primarily by a lack of effective protection against the harmful effects of neutrophil elastase due to the low AAT levels in the lung. Patients may also develop liver disease due to polymerisation of AAT within hepatocytes. Consequently there has been much research over the years into AAT augmentation therapy in patients with lung disease, initially intravenously, and more recently in inhaled forms. This review article will discuss the role of augmentation therapy in AATD and the current status of recombinant AAT. The potential for other therapeutic strategies, such as blocking polymer formation, enhancing autophagy, gene therapy and stem cell-based treatment, will also be discussed more briefly.

The molecular and cellular pathology of α₁-antitrypsin deficiency

Since its discovery 50 years ago, α₁-antitrypsin deficiency has represented a case study in molecular medicine, with careful clinical characterisation guiding genetic, biochemical, biophysical, structural, cellular, and in vivo studies. Here we highlight the milestones in understanding the disease mechanisms and show how they have spurred the development of novel therapeutic strategies. α₁-Antitrypsin deficiency is an archetypal conformational disease. Its pathogenesis demonstrates the interplay between protein folding and quality control mechanisms, with aberrant conformational changes causing liver and lung disease through combined loss- and toxic gain-of-function effects. Moreover, α₁-antitrypsin exemplifies the ability of diverse proteins to self-associate into a range of morphologically distinct polymers, suggesting a mechanism for protein and cell evolution.

The design of a new truncated and engineered alpha1-antitrypsin based on theoretical studies: an antiprotease therapeutics for pulmonary diseases

Alpha 1- antitrypsin (α1AT) a 54 kDa glycoprotein is a protease inhibitor. In the absence of α1AT, elastase released by lung macrophages, was not inhibited and lead to elastin breakdown and pulmonary problems such as emphysema or COPD. α1AT has three site of N-glycosylation and a characteristic reactive central loop (RCL). As small-scale medicines are preferred for pulmonary drug delivery, in this study α1ATs (1, 2, 3, 4 and 5) were engineered and shortened from the N-terminal region. In order to investigate the effect of different mutations and the deletion of 46 amino acids theoretical studies were performed. Homology modeling was performed to generate the 3D structure of α1ATs. The 10 ns Molecular Dynamic (MD) simulations were carried out to refine the models. Results from MD and protein docking showed that α1AT2 has the highest binding affinity for neutrophil elastase, provided the basis for the experimental phase in which sequences from the five α1AT constructs were inserted into the expression vector pGAPZα and expressed in the yeast Pichia pastoris. Although, the α1AT2 construct has the highest inhibitory activity even more that the native construct (α1AT5), results indicated the presence of protease inhibitory function of all the proteins' construct against elastase.

Effect of recombinant α1-antitrypsin Fc-fused (AAT-Fc)protein on the inhibition of inflammatory cytokine production and streptozotocin-induced diabetes

α1-Antitrypsin (AAT) is a member of the serine proteinase inhibitor family that impedes the enzymatic activity of serine proteinases, including human neutrophil elastase, cathepsin G and neutrophil proteinase 3. Here, we expressed recombinant AAT by fusing the intact AAT gene to the constant region of IgG1 to generate soluble recombinant AAT-Fc protein. The recombinant AAT-Fc protein was produced in Chinese hamster ovary (CHO) cells and purified using mini-protein A affinity chromatography. Recombinant AAT-Fc protein was tested for antiinflammatory function and AAT-Fc sufficiently suppressed tumor necrosis factor (TNF)-α-induced interleukin (IL)-6 in human peripheral blood mononuclear cells (PBMCs) and inhibited cytokine-induced TNFα by different cytokines in mouse macrophage Raw 264.7 cells. However, AAT-Fc failed to suppress lipopolysaccharide-induced cytokine production in both PBMCs and macrophages. In addition, our data showed that AAT-Fc blocks the development of hyperglycemia in a streptozotocin-induced mouse model of diabetes. Interestingly, we also found that plasma-derived AAT specifically inhibited the enzymatic activity of elastase but that AAT-Fc had no inhibitory effect on elastase activity.

Deficiency of α-1-antitrypsin influences systemic iron homeostasis

There is evidence that proteases and antiproteases participate in the iron homeostasis of cells and living systems. We tested the postulate that α-1 antitrypsin (A1AT) polymorphism and the consequent deficiency of this antiprotease in humans are associated with a systemic disruption in iron homeostasis. Archived plasma samples from Alpha-1 Foundation (30 MM, 30 MZ, and 30 ZZ individuals) were analyzed for A1AT, ferritin, transferrin, and C-reactive protein (CRP). Plasma samples were also assayed for metals using inductively coupled plasma atomic emission spectroscopy (ICPAES). Plasma levels of A1AT in MZ and ZZ individuals were approximately 60% and 20% of those for MM individuals respectively. Plasma ferritin concentrations in those with the ZZ genotype were greater relative to those individuals with either MM or MZ genotype. Plasma transferrin for MM, MZ, and ZZ genotypes showed no significant differences. Linear regression analysis revealed a significant (negative) relationship between plasma concentrations of A1AT and ferritin while that between A1AT and transferrin levels was not significant. Plasma CRP concentrations were not significantly different between MM, MZ, and ZZ individuals. ICPAES measurement of metals confirmed elevated plasma concentrations of nonheme iron among ZZ individuals. Nonheme iron concentrations correlated (negatively) with levels of A1AT. A1AT deficiency is associated with evidence of a disruption in iron homeostasis with plasma ferritin and nonheme iron concentrations being elevated among those with the ZZ genotype.

Alpha-1 Antitrypsin Deficiency PI*Z and PI*S Gene Frequency Distribution Using on Maps of the World by an Inverse Distance Weighting (IDW) Multivariate Interpolation Method

BACKGROUND

Currently, there is a remarkable lack of genetic epidemiological studies on alpha 1-antitrypsin (AAT) deficiency in about half of the 193 countries of the World. This fact impedes the establishment of a true prevalence pattern of this deleterious hereditary disorder in extensive regions of human population. 2.

OBJECTIVES

The aim of the present study was to generate detailed maps of the frequency distribution of the two most frequent AAT deficiency alleles (i.e., PI*S and PI*Z) in all areas of the World. 3.

MATERIALS AND METHODS

Available data provided by epidemiological studies performed in 94 of 193 countries worldwide was used to develop detailed maps of these two alleles, We employed an informatics mathematical approach, namely: the ArcMap [a component of ESRI's ArcGIS Geographical Information System (GIS), for Microsoft Windows], based on the inverse distance weighting (IDW) multivariate interpolation method, which creates new numerical points from known data, using a simple logarithm based in the distance existing between them 4.

RESULTS

In this method, PI*S and PI*Z frequencies were represented by colored scales, where qualitative colors were converted into quantitative data, providing information on their distribution in all parts of the world. This approach not only confirmed our previous data, but also provided digital images of the remaining regions of all continents. 5.

CONCLUSIONS

By using this approach, striking differences were found among regions, and unsuspected significant values of the PI*S and PI*Z alleles frequencies were obtained for several geographic regions where have not been studied yet. In fact, some of these regions might be considered as priority targets for further screening studies on AAT deficiency, in order to identify, and properly manage, individuals at risk for the diverse adverse health effects associated with AAT deficiency.

Role of cockroach proteases in allergic disease

Allergic asthma is on the rise in developed countries, and cockroach exposure is a major risk factor for the development of asthma. In recent years, a number of studies have investigated the importance of allergen-associated proteases in modulating allergic airway inflammation. Many of the studies have suggested the importance of allergen-associated proteases as having a direct role on airway epithelial cells and dendritic cells. In most cases, activation of the protease activated receptor (PAR)-2 has been implicated as a mechanism behind the potent allergenicity associated with cockroaches. In this review, we focus on recent evidence linking cockroach proteases to activation of a variety of cells important in allergic airway inflammation and the role of PAR-2 in this process. We will highlight recent data exploring the potential mechanisms involved in the biological effects of the allergen.

Expanding the clinical indications for α(1)-antitrypsin therapy

α(1)-Antitrypsin (AAT) is a 52-kDa circulating serine protease inhibitor. Production of AAT by the liver maintains 0.9-1.75 mg/mL circulating levels. During acute-phase responses, circulating AAT levels increase more than fourfold. In individuals with one of several inherited mutations in AAT, low circulating levels increase the risk for lung, liver and pancreatic destructive diseases, particularly emphysema. These individuals are treated with lifelong weekly infusions of human plasma-derived AAT. An increasing amount of evidence appears to suggest that AAT possesses not only the ability to inhibit serine proteases, such as elastase and proteinase-3 (PR-3), but also to exert antiinflammatory and tissue-protective effects independent of protease inhibition. AAT modifies dendritic cell maturation and promotes T regulatory cell differentiation, induces interleukin (IL)-1 receptor antagonist and IL-10 release, protects various cell types from cell death, inhibits caspases-1 and -3 activity and inhibits IL-1 production and activity. Importantly, unlike classic immunosuppressants, AAT allows undeterred isolated T-lymphocyte responses. On the basis of preclinical and clinical studies, AAT therapy for nondeficient individuals may interfere with disease progression in type 1 and type 2 diabetes, acute myocardial infarction, rheumatoid arthritis, inflammatory bowel disease, cystic fibrosis, transplant rejection, graft versus host disease and multiple sclerosis. AAT also appears to be antibacterial and an inhibitor of viral infections, such as influenza and human immunodeficiency virus (HIV), and is currently evaluated in clinical trials for type 1 diabetes, cystic fibrosis and graft versus host disease. Thus, AAT therapy appears to have advanced from replacement therapy, to a safe and potential treatment for a broad spectrum of inflammatory and immune-mediated diseases.

A review of augmentation therapy for alpha-1 antitrypsin deficiency

INTRODUCTION

Alpha-1 antitrypsin deficiency (AATD) is a relatively common, but under-recognized condition which manifests commonly with liver cirrhosis and emphysema. Specific therapy for lung-affected individuals with AATD is augmentation therapy, which consists of intravenous infusion of purified human plasma-derived alpha-1 antitrypsin (AAT). Augmentation therapy was first approved by the United States Food and Drug Administration (FDA) in 1987 for emphysema associated with severe AATD and today, six augmentation therapy preparations, all of which derive from pooled human plasma, have received FDA approval.

AREAS COVERED

This paper reviews augmentation therapy for AATD, including the various available commercial preparations, their processing and biochemical differences, evidence regarding biochemical and clinical efficacy, patterns of clinical use, adverse effect profiles, cost-effectiveness and potential uses in conditions other than emphysema associated with AATD. Novel and emerging strategies for treating AATD are briefly discussed next, including alternative dosing and administration strategies, recombinant preparations, small molecule inhibitors of neutrophil elastase and of AAT polymerization, autophagy-enhancing drugs and gene therapy approaches.

EXPERT OPINION

We conclude with a discussion of our approach to managing patients with AATD and use of augmentation therapy.

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.

A review of α1-antitrypsin deficiency

α(1)-Antitrypsin (AAT) deficiency is an underrecognized genetic condition that affects approximately 1 in 2,000 to 1 in 5,000 individuals and predisposes to liver disease and early-onset emphysema. AAT is mainly produced in the liver and functions to protect the lung against proteolytic damage (e.g., from neutrophil elastase). Among the approximately 120 variant alleles described to date, the Z allele is most commonly responsible for severe deficiency and disease. Z-type AAT molecules polymerize within the hepatocyte, precluding secretion into the blood and causing low serum AAT levels (∼ 3-7 μM with normal serum levels of 20-53 μM). A serum AAT level of 11 μM represents the protective threshold value below which the risk of emphysema is believed to increase. In addition to the usual treatments for emphysema, infusion of purified AAT from pooled human plasma-so-called "augmentation therapy"-represents a specific therapy for AAT deficiency and raises serum levels above the protective threshold. Although definitive evidence from randomized controlled trials of augmentation therapy is lacking and therapy is expensive, the available evidence suggests that this approach is safe and can slow the decline of lung function and emphysema progression. Promising novel therapies are under active investigation.

Why has it been so difficult to prove the efficacy of alpha-1-antitrypsin replacement therapy? Insights from the study of disease pathogenesis

Alpha-1-antitrypsin is the most abundant circulating protease inhibitor. It is mainly produced by the liver and secreted into the circulation where it acts to prevent excessive proteolytic damage in the lungs by the enzyme neutrophil elastase. The most common severe deficiency allele is the Z mutation, which causes the protein to self-associate into ordered polymers. These polymers accumulate within hepatocytes to cause liver damage. The resulting lack of circulating α₁-antitrypsin predisposes the Z homozygote to proteolytic lung damage and emphysema. Other pathways may also contribute to the development of lung disease. In particular, polymers of Z α₁-antitrypsin can form within the lung where they act as a pro-inflammatory stimulus that may exacerbate protease-mediated lung damage. Researchers recognized in the 1980s that plasma α₁-antitrypsin levels could be restored by intravenous infusions of purified human protein. Alpha-1-antitrypsin replacement therapy was introduced in 1987 but subsequent clinical trials have produced conflicting results, and to date there remains no widely accepted clinical evidence of the efficacy of α₁-antitrypsin replacement therapy. This review addresses our current understanding of disease pathogenesis in α₁-antitrypsin deficiency and questions why this treatment in isolation may not be effective. In particular it discusses the possible role of α₁-antitrypsin polymers in exacerbating intrapulmonary inflammation and attenuating the efficacy of α₁-antitrypsin replacement therapy.