AAT Deficiency Research Articles

Gene Delivery of Alpha-1-Antitrypsin Using Recombinant Adeno-Associated Virus (rAAV).

The challenge for alpha-1-antitrypsin (AAT also known as SERPINA1) gene therapy is to achieve long term and high levels of AAT production. Recombinant adeno-associated virus (rAAV) vector has several advantages for AAT gene delivery including no viral genes in the vector, no requirement of integration for long-term transgene expression, low immunogenicity, and wide tropism. AAV-mediated AAT gene therapy has been developed and tested in animal models for AAT deficiency, type 1 diabetes, rheumatoid arthritis, and osteoporosis. AAV-mediated AAT gene therapy has also been tested in clinical studies and has shown promising results. Here we describe the methods of rAAV-AAT vector construction and production as well as AAT gene delivery through (1) liver-directed, (2) muscle-directed, and (3) mesenchymal stem cell (MSC)-mediated routes. We will also describe methods for the evaluation of AAT expression for each delivery approach.

Cellular Models for the Serpinopathies.

Our current knowledge about the cellular mechanisms underlying serpin-related disorders, the serpinopathies, is predominantly based on studies in cell culture models of disease, particularly for alpha-1 antitrypsin (AAT, SERPINA1) deficiency causing emphysema and the familial encephalopathy with neuroserpin (NS, SERPINI1) inclusion bodies (FENIB). FENIB, a neurodegenerative dementia, is caused by polymerization of NS (Miranda and Lomas, Cell Mol Life Sci 63:709-722, 2006; Roussel BD et al., Epileptic Disor 18:103-110, 2016), while AAT deficiency presents as a result of several divergent mutations in the AAT gene that cause lack of protein synthesis orcomplete intracellular degradation (null variants) or polymer formation (polymerogenic variants) (Lomas et al., J Hepatol 65:413-424, 2016; Greene et al., Nat Rev Dis Primers 2:16051, 2016; Ferrarotti et al. Orphanet J Rare D 9:172, 2014). Both diseases have been extensively modeled in cell culture systems by expressing mutant variants in a variety of ways. Here we describe the methodologies we follow in our cell model systems used to examine serpin disorders.

Therapeutic Genome Editing With CRISPR/Cas9 in a Humanized Mouse Model Ameliorates A1-Antitrypsin Deficiency Phenotype

A1-antitrypsin (AAT) is a circulating serine protease inhibitor secreted from the liver and important in preventing proteolytic neutrophil elastase associated tissue damage, primarily in lungs. In humans, AAT is encoded by the SERPINA1 (hSERPINA1) gene in which a point mutation (commonly referred to as PiZ) causes aggregation of the miss-folded protein in hepatocytes resulting in subsequent liver damage. In an attempt to rescue the pathologic liver phenotype of a mouse model of human AAT deficiency (AATD), we used adenovirus to deliver Cas9 and a guide-RNA (gRNA) molecule targeting hSERPINA1. Our single dose therapeutic gene editing approach completely reverted the phenotype associated with the PiZ mutation, including circulating transaminase and human AAT (hAAT) protein levels, liver fibrosis and protein aggregation. Furthermore, liver histology was significantly improved regarding inflammation and overall morphology in hSERPINA1 gene edited PiZ mice. Genomic analysis confirmed significant disruption to the hSERPINA1 transgene and quantitative mRNA analysis showed a reduction in hAAT, fibrosis and hepatocyte proliferation as a result of editing. Our findings indicate that therapeutic gene editing in hepatocytes is possible in an AATD mouse model.

Pulmonary langerhans cell histiocytosis - insight into the incidence of alfa-1-antitrypsin (A1ATD) deficiency alleles.

The alpha-1 antitrypsin deficiency (A1ATD) is one of the three most common genetic disorders in Caucasians. It considerably increases the risk of progressive obstructive lung diseases, mostly chronic obstructive pulmonary disease. There is no data regarding prevalence of main, clinically most important A1ATD alleles PI*Z and PI*S in patients with pulmonary Langerhans cell histiocytosis (PLCH). PLCH is not only strongly linked to the cigarette smoking, but is also characterised by polycystic lung lesions. The goal of the study was to assess the incidence of A1ATD alleles in patients with PLCH. Blood samples were collected from 34 adult patients (14 women and 20 men), with histologically confirmed PLCH. AAT serum concentration was assessed by nephelometry and PI-phenotype, identified by isoelectrofocusing. The PI*S and PI*Z alleles were confirmed by genotyping usisng real-time PCR. Deficiency alleles PI*Z and PI*S were detected in 3 patients (one woman and 2 men), respectively in 5.88% and 2.94%. The estimated incidence of deficiency alleles was 29.4/1000 (95% CI; 10-69.5) for PI*Z and 14.7/1000(95%CI; 13.9-43.3) for PI*S. According to our previous reports, the expected prevalence of PI*Z and PI*S alleles in general Polish population was 13.7/1000 (95% CI 5.8-21.5), and 7,6/1000 (95% CI 1.7-13.5) respectively. The incidence of main A1AT deficiency alleles in patients with PLCH seems higher than in general Polish population. The study is on-going.

Large-scale purification of high purity α1-antitrypsin from Cohn Fraction IV with virus inactivation by solvent/detergent and dry-heat treatment.

α1-Antitrypsin (AAT) is widely used to treat patients with congenital AAT deficiency. Cohn Fraction IV (Cohn F IV) is normally discarded during the manufacturing process of albumin but contains approximately 33% of plasma AAT. We established a new process for large-scale purification of AAT from it. liquid chromatography-electrospray ionization-tandem mass spectrometry and high-performance liquid chromatography were applied for qualitative identification and composition analysis, respectively. Stabilizers were optimized for AAT activity protection during lyophilization and dry-heat. Virus inactivation by dry-heat and solvent/detergent (S/D) was validated on a range of viruses. AAT with purity of 95.54%, specific activity of 3,938.5IU/mg, and yield of 26.79%, was achieved. More than 95% activity was reserved after S/D. More than 96% activity was obtained after lyophilization or dry-heat. After S/D, pseudorabies virus (PRV) and vesicular stomatitis virus (VSV) were inactivated below detectable level within 1H. Virus titer reductions of more than 5.50 log10 and 5.38 log10 were achieved for PRV and VSV, respectively. Porcine parvovirus and encephalomyocarditis virus were inactivated by 3.17 log10 and 5.88 log10 reduction after dry-heat. The advantages of this process, including suitability for large-scale production, high purity, better utilization of human plasma, viral safety, commercial and inexpensive chromatography medium, may facilitate its further application.

Case-finding for alpha1-antitrypsin deficiency in Kazakh patients with COPD

Background Alpha-1-antitrypsin deficiency (AATD) is an under-diagnosed condition in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to screen for AATD in Kazakh patients with COPD using dried blood spot specimens.MethodsThe alpha1-antitrypsin (AAT) concentration was determined by nephelometry, PCR was used to detect PiS and PiZ alleles; and isoelectric focusing was used to confirm questionable genotype results and detect rare AAT variants.ResultsTo this aim, 187 Kazakh subjects with COPD were recruited. Blood samples were collected as dried blood spot. Genotyping of 187 samples revealed 3 (1.6%) PI*MZ and 1 (0.53%) PI*MS, Phenotyping identified also two sample (1.1%) with phenotype PiMI. Allelic frequencies of pathological mutations Z, S and I resulted 0.8%, 0.3%, 0.5%, respectively, in COPD Kazakh population.ConclusionThis study proved that AATD is present in the Kazakh population. These results support the general concept of targeted screening for AAT deficiency in countries like Kazakhstan, with a large population of COPD patients and low awareness among care-givers about this genetic condition.

Identification of a new defective SERPINA1 allele (PI*Zla palma) encoding an alpha-1-antitrypsin with altered glycosylation pattern.

Alpha-1-antitrypsin (AAT) deficiency is a genetic condition that arises from mutations in the SERPINA1 gene and predisposes to develop pulmonary emphysema and, less frequently, liver disease. Occasionally, new defective SERPINA1 alleles are detected as an outcome of targeted-screening programs or case-findings. This study began with a female patient showing bronchial hyperreactivity. Serum level and phenotype for AAT was analysed by immunonephelometry and isoelectric focusing electrophoresis. The SERPINA1 gene of the proband was genotyped by PCR amplification and DNA sequencing. Analysis of AAT deficiency was extended to the proband's family. An abnormal AAT variant that migrated to a more cathodal position than PiZ AAT was detected in the proband's serum. Genetic analysis demonstrated that proband is heterozygous for a new defective SERPINA1 allele (PI*Zla palma) characterized by the c.321C>A (p.Asn83Lys) mutation in the M1Val213 background. This mutation abolishes the N-glycosylation site in position 83 of the mature AAT. Eight relatives of the proband are carriers of the PI*Zla palma allele and four of them have shown symptoms of bronchial asthma or bronchial hyperreactivity. The mean α1AT level in the serum of PI*MZla palma individuals was 87.1mg/dl. The reduction in circulating AAT levels associated to the PI*Zla palma allele was similar to that of PI*Z allele, representing a risk of impairment in lung function.

Case-finding for alpha1-antitrypsin deficiency in Kazakh patients with COPD

Background: Alpha-1-antitrypsin deficiency (AATD) is an under-diagnosed condition in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to screen for AATD in Kazakh patients with COPD using dried blood spot specimens.
 Methods: The alpha1-antitrypsin (AAT) concentration was determined by nephelometry, PCR was used to detect PiS and PiZ alleles; and isoelectric focusing was used to confirm questionable genotype results and detect rare AAT variants.
 Results: To this aim, 187 Kazakh subjects with COPD were recruited. Blood samples were collected as dried blood spot. Genotyping of 187 samples revealed 3 (1.6%) PI*MZ and 1 (0.53%) PI*MS, Phenotyping identified also two sample (1.1%) with phenotype PiMI. Allelic frequencies of pathological mutations Z, S and I resulted 0.8%, 0.3%, 0.5%, respectively, in COPD Kazakh population.
 Conclusions: This study proved that AATD is present in the Kazakh population. These results support the general concept of targeted screening for AAT deficiency in countries like Kazakhstan, with a large population of COPD patients and low awareness among care-givers about this genetic condition.

Down-regulation of hepatocyte nuclear factor-4α and defective zonation in livers expressing mutant Z α1-antitrypsin.

The findings of this study are consistent with the concept that abnormal AAT protein conformation and intrahepatic accumulation have broad effects on metabolic liver functions. (Hepatology 2017;66:124-135).

Alpha-2 Macroglobulin Serum Level in Patients with Alpha-1 Antitrypsin Deficiency

Background and objectives Alpha-2 Macroglobulin (A2M) is a plasma protein with proteolytic effects on many proteases. In patients with an inborn alpha-1 antitrypsin deficiency (AATD) the homeostasis between proteases and antiproteases is disturbed. The aim of this study was to compare the levels of AAT and A2 M in patients and controls. We hypothesized that in patients with AATD A2 M levels are elevated. Methods Patients with AATD (polymorphism Pi*ZZ, Pi*SZ, Pi*MZ and rare gene variants) as well as healthy volunteers (Pi*MM) were tested for A2 M and AAT levels. The concentration of the proteins was measured by nephelometry. The polymorphisms Pi*Z and Pi*S were detected by polymerase chain reaction (PCR), the rare genetic variants were identified by sequencing. Results In our study, a total of 291 individuals were included. It could be shown that a significant increase in A2 M levels in the serum could be observed in the presence of a gene polymorphism (Pi*ZZ) and an alpha-1 antitrypsin serum level < 50 mg/dl compared to the healthy volunteers. Conclusions In this study, an inverse correlation between the serum levels of AAT and A2 M was found in the presence of a gene polymorphism (Pi*ZZ). Further studies are necessary to elucidate the clinical significance of increased A2 M serum levels in patients with severe AAT deficiency Pi*ZZ and rare gene variants whose AAT serum level is < 50 mg/dl.

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.

Liver function in alpha-1-antitrypsin deficient individuals at 37 to 40 years of age.

Severe alpha-1-antitrypsin (AAT) deficiency (PiZZ) is a risk factor for liver disease, but the prevalence of liver cirrhosis and hepatocellular cancer in PiZZ adults is unknown. The risk of liver disease in adults with moderate AAT deficiency (PiSZ) is also unknown. A cohort of 127 PiZZ, 2 PiZnull, 54 PiSZ, and 1 PiSnull individuals were identified by the Swedish national neonatal AAT screening program between 1972 and 1974, when all 200,000 newborn infants in Sweden were screened for AAT deficiency. The cohort has been followed up since birth. Our aim was to study liver function and signs of liver disease in this cohort at 37 to 40 years of age in comparison with a matched, random sample of control subjects identified from the population registry.Eighty seven PiZZ, 32 PiSZ, and 92 control subjects (PiMM) answered a questionnaire on medication and alcohol consumption and provided blood samples. Liver stiffness was assessed by Acoustic Radiation Force Impulse (ARFI) elastography in 32 PiZZ, 15 PiSZ, and 51 PiMM subjects.The median of liver function tests and procollagen-III-peptide were within the normal range in all Pi subgroups. However, the PiZZ men had significantly higher plasma bilirubin than the PiMM men (P = 0.018). Plasma ɣ-glutamyl transferase (GGT) was significantly higher in the PiZZ men (P = 0.009) and the PiSZ men (P = 0.021) compared with the PiMM men. The median of liver stiffness was significantly higher in the PiZZ men (P = 0.037) and the PiSZ men (P = 0.032) compared with the PiMM men. The PiZZ women taking medication influencing liver enzymes had significantly higher GGT than the PiMM women on the corresponding treatment (P = 0.023).These AAT-deficient individuals identified by neonatal screening have normal plasma levels of liver function tests, and no clinical signs indicating liver disease at the age of 37 to 40 years. However, bilirubin, GGT, and liver stiffness are significantly higher in PiZZ men than PiMM men.

New process for purifying high purity α1-antitrypsin from Cohn Fraction IV by chromatography: A promising method for the better utilization of plasma.

α1-antitrypsin (AAT) is a 52kDa serine protease inhibitor that is abundant in plasma. It is synthesized mainly by hepatic cells, and widely used to treat patients with emphysema due to congenital deficiency of AAT. A new isolation method for the purification of AAT from Cohn Fraction IV (Cohn F IV) is described. Cohn F IV is usually discarded as a byproduct from Cohn process. Using Cohn F IV as starting material does not interfere with the production of other plasma proteins and the cost of purification could be reduced greatly. Parameters of each step during purification were optimized, 15% polyethyleneglycol (PEG) concentration and pH 5.2 for PEG precipitation, elution with 0.05M sodium acetate and pH 4.7 for ion-exchange chromatography, and two steps blue sepharose affinity chromatography were chosen for AAT purification. The final protein with purity of 98.17%, specific activity of 3893.29 IU/mg, and yield of 28.35%, was achieved. Western blotting was applied for qualitative identification of final product, which specifically reacted with goat anti-human AAT antibody. LC-ESI-MS/MS was also employed to confirm the final protein. High performance liquid chromatography was used to analyze the composition of purified protein suggesting that pure protein was achieved. The molecular weight of AAT is 51062.77Da which was identified by LC-MS-MS. The manufacturing process described here may make better use of human plasma with Cohn F IV as starting material. The simple process described in this study is simple and inexpensive, it has a potential value for large scale production.

α-1 Antitrypsin Enhances Islet Engraftment by Suppression of Instant Blood-Mediated Inflammatory Reaction.

Islet cell transplantation has limited effectiveness because of an instant blood-mediated inflammatory reaction (IBMIR) that occurs immediately after cell infusion and leads to dramatic β-cell death. In intraportal islet transplantation models using mouse and human islets, we demonstrated that α-1 antitrypsin (AAT; Prolastin-C), a serine protease inhibitor used for the treatment of AAT deficiency, inhibits IBMIR and cytokine-induced inflammation in islets. In mice, more diabetic recipients reached normoglycemia after intraportal islet transplantation when they were treated with AAT compared with mice treated with saline. AAT suppressed blood-mediated coagulation pathways by diminishing tissue factor production, reducing plasma thrombin-antithrombin complex levels and fibrinogen deposition on islet grafts, which correlated with less graft damage and apoptosis. AAT-treated mice showed reduced serum tumor necrosis factor-α levels, decreased lymphocytic infiltration, and decreased nuclear factor (NF)-κB activation compared with controls. The potent anti-inflammatory effect of AAT is possibly mediated by suppression of c-Jun N-terminal kinase (JNK) phosphorylation. Blocking JNK activation failed to further reduce cytokine-induced apoptosis in β-cells. Taken together, AAT significantly improves islet graft survival after intraportal islet transplantation by mitigation of coagulation in IBMIR and suppression of cytokine-induced JNK and NF-κB activation. AAT-based therapy has the potential to improve graft survival in human islet transplantation and other cellular therapies on the horizon.

THE DIAGNOSTIC AND CLINICAL VALUE OF DETERMINATION OF α1-ANTITRYPSIN PHENOTYPE IN SYSTEMIC VASCULITIDES

α1-Antitrypsin (α1-AT) deficiency is a common genetic disorder characterized by low serum α1-AT levels and a clinical manifestation of pulmonary emphysema and liver disease. In addition to its classical manifestations, α1-AT deficiency frequently accompanies granulomatosis with polyangiitis (GPA); in this case the role of α1-AT deficiency in the clinical course of GPA has not been defined. Objective: to estimate the prevalence of pathological α1-AT phenotypes in GPA and other systemic vasculitides (SV) and to determinate their impact on the clinical course of GPA. Subjects and methods. The investigation enrolled 86 patients with SV, including GPA (n=47), microscopic polyangiitis (MPA) (n=16), eosinophilic granulomatosis with polyangiitis (EGPA) (n=12), and polyarteritis nodosa (PAN) (n=11). A control group included 46 healthy donors. Isoelectric focusing was used to phenotype α1-AT in blood samples and its concentrations were determined. The phenotypes of α1-AT were compared with the overall SV activity index using the Birmingham Vasculitis Activity Score (BVAS), the vasculitis damage index (VDI), the nature of an organ lesion, and the markers of immune inflammation (proteinase 3-antineutrophil cytoplasmic antibodies, total IgG, and C3 and C4 fractions of the complement system). Results and discussion. Pathological α1-AT phenotypes were detected in 17% (8/47) of the patients with GPA, 6.25% (1/16) of those with MPA and absent in EGPA and PAN. Patients with GPA had PiZZ (n=1), PiMZ (n=4), PiMF (n=2), and PiMS (n=1) phenotypes; those with MPA had a PiMS-phenotype. The detection of a pathological α1-AT phenotype in patients with GPA was characterized by the high values of BVAS and VDI (p <0.05) and the elevated levels of serum creatinine (p<0.01), anti-proteinase 3 antibodies, IgG, C3 and C4 fractions of the complement system (p<0.05). Conclusion. Pathological α1-AT phenotypes are more frequently detected in patients with GPA, which is accompanied by an enhanced immunological activity of the disease and high activity and damage indices.

Pathophysiology of Alpha-1 Antitrypsin Deficiency Liver Disease.

Classical alpha-1 antitrypsin (a1AT) deficiency is an autosomal recessive disease associated with an increased risk of liver disease in adults and children, and with lung disease in adults (Teckman and Jain, Curr Gastroenterol Rep 16(1):367, 2014). The vast majority of the liver disease is associated with homozygosity for the Z mutant allele, the so-called PIZZ. These homozygous individuals synthesize large quantities of a1AT mutant Z protein in the liver, but the mutant protein folds improperly during biogenesis and approximately 85% of the molecules are retained within the hepatocytes rather than appropriately secreted. The resulting low, or "deficient," serum level leaves the lungs vulnerable to inflammatory injury from uninhibited neutrophil proteases. Most of the mutant Z protein molecules retained within hepatocytes are directed into intracellular proteolysis pathways, but some molecules remain in the endoplasmic reticulum for long periods of time. Some of these molecules adopt an unusual aggregated or "polymerized" conformation (Duvoix et al., Rev Mal Respir 31(10):992-1002, 2014). It is thought that these intracellular polymers trigger a cascade of intracellular injury which can lead to end-organ liver injury including chronic hepatitis, cirrhosis, and hepatocellular carcinoma (Lindblad et al., Hepatology 46(4):1228-1235, 2007). The hepatocytes with the largest accumulations of mutant Z polymers undergo apoptotic death and possibly other death mechanisms. This intracellular death cascade appears to involve ER stress, mitochondrial depolarization, and caspase cleavage, and is possibly linked to autophagy and redox injury. Cells with lesser burdens of mutant Z protein proliferate to maintain the liver cell mass. This chronic cycle of cell death and regeneration activates hepatic stellate cells and initiates the process of hepatic fibrosis. Cirrhosis and hepatocellular carcinoma then result in some patients. Since not all patients with the same homozygous PIZZ genotype develop end-stage disease, it is hypothesized that there is likely to be a strong influence of genetic and environmental modifiers of the injury cascade and of the fibrotic response.

Understanding Lung Deposition of Alpha-1 Antitrypsin in Acute Experimental Mouse Lung Injury Model Using Fluorescence Microscopy.

Human plasma-derived α1-antitrypsin (AAT) delivered by intravenous infusion is used as augmentation therapy in patients with emphysema who have a genetic mutation resulting in deficiency of AAT. Inhalation is an alternative route of administration that can potentially increase the efficacy and convenience of treatment. This study was conducted to determine whether delivery to the lungs, initially via the intratracheal (IT) route of administration, would deliver efficacious levels of a recombinant AAT (rAAT) to the site of action in the lungs in mice. 125I-radiolabeled rAAT, fluorophore-conjugated rAAT (rAAT-Alexa488), and NE680 (neutrophil elastase 680, a silent fluorescent substrate of neutrophil elastase which fluoresces in the near-infrared range upon activation by neutrophil elastase) were used to characterize the pharmacokinetics and tissue distribution profile, distribution of rAAT within the lung, and efficacy of rAAT to inhibit neutrophil elastase at the site of action, respectively. The study has demonstrated that rAAT was able to gain access to locations where neutrophil elastase was localized. The histochemical quantification of rAAT activity relative to dose at the site of action provided here will improve confidence in predicting the human dose via the inhalation route.

Phenotyping of α-1-Antitrypsin by liquid chromatography–high resolution mass spectrometry

More than seventy-five isotypes of α-1-antitrypsin (AAT) have been described. To assess risks associated with AAT deficiency, isotype identification is necessary. Isoelectric focusing (IEF) is traditionally used for isotype differentiation, however, IEF has limited scope since it is a manual procedure that is not suitable for automation, and antitrypsin variants must differ in net charge in order to be resolved. In comparison, mass spectrometric assays are easily automated and offer a more complete solution for characterization of proteins. To capitalize on these advantages, we have developed a qualitative top-down liquid chromatography–mass spectrometry (LC–MS) method for selective phenotyping of AAT. This technique requires no sample pretreatment, and has the potential for use in routine clinical diagnostics. We have validated our LC–MS results against both DNA sequencing and IEF. Thus far, this method has identified the AAT variants PLowell, S and Z, as well as unique fragments shared by different M alleles. Its high selectivity is indirectly illustrated by the detection of a variant carrying the amino acid substitution p.Ala308Ser, which cannot be visualized by IEF.

Exploration of α1-antitrypsin treatment protocol for islet transplantation: dosing plan and route of administration.

Lifelong weekly infusions of human α1-antitrypsin (hAAT) are currently administered as augmentation therapy for patients with genetic AAT deficiency (AATD). Several recent clinical trials attempt to extend hAAT therapy to conditions outside AATD, including type 1 diabetes. Because the endpoint for AATD is primarily the reduction of risk for pulmonary emphysema, the present study explores hAAT dose protocols and routes of administration in attempt to optimize hAAT therapy for islet-related injury. Islet-grafted mice were treated with hAAT (Glassia; intraperitoneally or subcutaneously) under an array of clinically relevant dosing plans. Serum hAAT and immunocyte cell membrane association were examined, as well as parameters of islet survival. Results indicate that dividing the commonly prescribed 60 mg/kg i.p. dose to three 20 mg/kg injections is superior in affording islet graft survival; in addition, a short dynamic descending dose protocol (240→120→60→60 mg/kg i.p.) is comparable in outcomes to indefinite 60 mg/kg injections. Although pharmacokinetics after intraperitoneal administration in mice resembles exogenous hAAT treatment in humans, subcutaneous administration better imitated the physiologic progressive rise of hAAT during acute phase responses; nonetheless, only the 60 mg/kg dose depicted an advantage using the subcutaneous route. Taken together, this study provides a platform for extrapolating an islet-relevant clinical protocol from animal models that use hAAT to protect islets. In addition, the study places emphasis on outcome-oriented analyses of drug efficacy, particularly important when considering that hAAT is presently at an era of drug-repurposing toward an extended list of clinical indications outside genetic AATD.

Preliminary Advancement for an Electrochemical Biosensor for Early Diagnosis of Alpha-1-Antitrypsin Deficiency

Electrochemical biosensors present a potential advance in the field of disease diagnosis by providing immediate and accurate results in the detection of pre-specified targets. In most cases, the successful diagnosis and treatment of diseases is reliant upon out-of-date testing instruments that are no longer adequate. For this reason, it is important to explore the novel combination of established testing methods with modern technology. For the case of alpha-1-antitrypsin (A1AT) deficiency (A1AD), a complete diagnosis currently requires a minimum of three individual tests performed using blood serum. The use of a specialized biosensor to detect a deficiency and the form of A1AT could potentially have a dramatic increase in diagnosing carriers of genetic mutations in the A1AT gene sequence that predispose them to early-onset emphysema (1). The main purpose of A1AT is to counter human neutrophil elastase (HNE). HNE is responsible for the removal of harmful bacteria in the lungs as well as other undesirable particles that may be present. When there is a lack of A1AT resulting in A1AD, the HNE will become in relative excess, resulting in the degradation of elastin, the elastic material of the lungs which may lead to emphysema development (2). Due to the challenges of diagnosing A1AD, it is often discovered after one exhibits symptoms of emphysema. The three separate tests that are currently used to diagnose A1AD are the determination of A1AT in the blood, followed by protein phenotyping, and then A1AT genotyping (3). All three tests are time intensive and require a patient’s serum for sampling. The use of an electrochemical biosensor could replace the need for all three of these tests within one instrument. The biosensor would incorporate an electrochemical quartz crystal nanobalance (EQCN) with an electrode surface that has been functionalized with a biological agent that would bind to an analyte that confirms A1AD. A visual representation of the electrode surface is provided in Figure 1 for the binding of an analyte on the functionalized gold surface. Lomant’s Reagent, dithiobis(succinimidyl propionate) (DSP), has been used in several other biosensors to functionalize the gold surface of the electrode (4). DSP is a preferred reagent due to the functionality provided by the carboxyl group as well as the length of the carbon backbone. An electrochemical biosensor allows for the measurement of a biological sample through redox responses by measuring both conductivity or resistance through the electrode as well as any changes in mass on the surface of the electrode by the EQCN. The dual functionality of the EQCN in measuring the electric and mass parameters allows for accurate detection of biological analytes and greatly reduces the concern for false negatives or positives. It is the goal of this work to develop and test an electrochemical biosensor with an EQCN that will be readily available in the medical field to allow accurate and timely results for the detection of A1AD. This technology has the potential to increase early detection and diagnosis of many different diseases which allows for early treatment and could potentially improve outcomes for those afflicted. Initial work has been performed to build a firm foundation of knowledge of the responses of the EQCN in appropriate media. Calibration testing has been established for the quartz crystals through numerous experiments. Thus far, the study is progressing into attaching DSP to the quartz crystal surface and measuring the electrochemical response of the system in preparation for biological analyte detection. Figure 1