Revascularization of pancreatic islet allografts is enhanced by α-1-antitrypsin under anti-inflammatory conditions

Impact of a Single Dose of Alpha-1-Antitrypsin in a Rat Model of Bilateral Kidney Ischemia Reperfusion Injury

INTRODUCTION

Renal ischemia reperfusion injury is a major cause of perioperative acute kidney injury. Alpha-1-antitrypsin (AAT), a protease inhibitor, might improve outcomes by reducing inflammation and apoptosis. We investigated the effects of a single intravenous dose of AAT immediately before ischemia in a rat bilateral renal clamping model.

METHODS

Both renal pedicles of male Sprague-Dawley rats were clamped (45 min). Plasma and renal tissue were collected at 3 h, 24 h, and 7 d. Intravenous AAT (60 mg/kg) was administered 5 min before clamping. Controls received saline. Shams underwent surgery without clamping or injection. Kidney function was assessed by plasma creatinine; injury by aspartate aminotransferase, heart-type-fatty-acid-binding-protein, and histopathology. Renal gene expression of tumor necrosis factor α, interleukin (IL)-6, heat shock protein 70, Chemokine (C-X-C motif) ligand 2, cyclo-oxygenase 2, endothelin-1, IL-10, heme oxygenase 1, B-cell lymphoma 2, and bcl-2-like protein 4 were determined by quantitative reverse transcriptase polymerase chain reaction.

RESULTS

None of the 3 h and 24 h end points were different between Control and AAT. In Sham, survival was 100% (6/6), 33% in Control (2/6), and 83% (5/6) in AAT (overall log-rank 0.03). At 7 d, plasma creatinine was lower with higher glomerular filtration rate in surviving AAT treated animals compared to Control (P < 0.001, P 0.03, respectively). These also had lower tumor necrosis factor α and IL-6 gene expression (P 0.001, P < 0.001, respectively).

CONCLUSIONS

These data suggest that a single intravenous dose of AAT immediately before ischemia might affect proinflammatory gene expression, glomerular filtration rate and animal survival at 1 wk after reperfusion despite an absence of improvement in early renal function and injury. These findings deserve further investigating in sufficiently powered studies including both sexes.

Local Alpha1-Antitrypsin Accelerates the Healing of Tympanic Membrane Perforation in Mice

BACKGROUND

Most tympanic membrane (TM) perforations heal spontaneously, but 10%-20% remain chronic and might lead to impaired hearing and recurrent middle ear infections. Alpha1-antitrypsin (AAT) is a circulating tissue-protective protein that is elevated under inflammatory conditions and is currently indicated for genetic AAT deficiency. Recently, AAT has been shown to promote tissue remodeling and inflammatory resolution.

OBJECTIVE

This study aimed to examine the effects of local clinical-grade AAT treatment on tissue repair in a mouse model of acute traumatic TM perforation.

METHODS

Wild-type mice underwent unilateral TM perforation and were either left untreated or treated locally with human AAT (9 × 10-3 mL at 20 mg/mL on days 0, 1, and 2; n = 15/group). The perforations were evaluated macroscopically on a serial basis. Mice were sacrificed on various days post-injury, and TMs were excised for gene analysis by RT-PCR.

RESULTS

There were no adverse reactions in hAAT-treated ears throughout the study period. Compared with untreated animals, TM closure occurred earlier in the treated group (days until full closure, median: 4 and 9, respectively). According to gene expression analysis, VEGF, TGFβ, and collagen-5A1 were induced earlier in AAT-treated mice (day 4-5 compared with day 9). Additionally, IL-10 expression levels were higher and IL-6 levels were lower in treated versus untreated mice.

CONCLUSION

A local tissue environment rich in AAT promotes early tissue repair in a perforated TM model both macroscopically and molecularly. Studies are underway to examine TM functionality and recombinant AAT formulations for micro-dosing in the format of a single local application.

LEVEL OF EVIDENCE

NA Laryngoscope, 2024.

Alpha-1 Antitrypsin Augmentation Therapy in Chronic Pancreatitis Patients Undergoing Total Pancreatectomy and Islet Autotransplantation: A Randomized, Controlled Study

Stress-induced islet graft loss during the peri-transplantation period reduces the efficacy of islet transplantation. In this prospective, randomized, double-blind clinical trial, we evaluated the safety and efficacy of 60 mg/kg human alpha-1 antitrypsin (AAT) or placebo infusion weekly for four doses beginning before surgery in chronic pancreatitis (CP) patients undergoing total pancreatectomy and islet autotransplantation (TP-IAT). Subjects were followed for 12 months post-TP-IAT. The dose of AAT was safe, as there was no difference in the types and severity of adverse events in participants from both groups. There were some biochemical signals of treatment effect with a higher oxygen consumption rate in AAT islets before transplantation and a lower serum C-peptide (an indicator of islet death) in the AAT group at 15 min after islet infusion. Findings per the statistical analysis plan using a modified intention to treat analysis showed no difference in the C-peptide area under the curve (AUC) following a mixed meal tolerance test at 12 months post-TP-IAT. There was no difference in the secondary and exploratory outcomes. Although AAT therapy did not show improvement in C-peptide AUC in this study, AAT therapy is safe in CP patients and there are experiences gained on optimal clinical trial design in this challenging disease.

Challenges and opportunities in the islet transplantation microenvironment: a comprehensive summary of inflammatory cytokine, immune cells, and vascular endothelial cells

It is now understood that islet transplantation serves as a β-cell replacement therapy for type 1 diabetes. Many factors impact the survival of transplanted islets, especially those related to the microenvironment. This review explored microenvironmental components, including vascular endothelial cells, inflammatory cytokines, and immune cells, and their profound effects on post-islet transplantation survival rates. Furthermore, it revealed therapeutic strategies aimed at targeting these elements. Current evidence suggests that vascular endothelial cells are pivotal in facilitating vascularization and nutrient supply and establishing a new microcirculation network for transplanted islets. Consequently, preserving the functionality of vascular endothelial cells emerges as a crucial strategy to enhance the survival of islet transplantation. Release of cytokines will lead to activation of immune cells and production and release of further cytokines. While immune cells hold undeniable significance in regulating immune responses, their activation can result in rejection reactions. Thus, establishing immunological tolerance within the recipient's body is essential for sustaining graft functionality. Indeed, future research endeavors should be directed toward developing precise strategies for modulating the microenvironment to achieve higher survival rates and more sustained transplantation outcomes. While acknowledging certain limitations inherent to this review, it provides valuable insights that can guide further exploration in the field of islet transplantation. In conclusion, the microenvironment plays a paramount role in islet transplantation. Importantly, we discuss novel perspectives that could lead to broader clinical applications and improved patient outcomes in islet transplantation.

Accelerated Wound Border Closure Using a Microemulsion Containing Non-Inhibitory Recombinant α1-Antitrypsin

Wound healing requires a non-compromising combination of inflammatory and anti-inflammatory processes. Human α1-antitrypsin (hAAT), a circulating glycoprotein that rises during acute-phase responses and during healthy pregnancies, is tissue-protective and tolerance-inducing; although anti-inflammatory, hAAT enhances revascularization. hAAT blocks tissue-degrading enzymes, including neutrophil elastase; it is, therefore, unclear how wound healing might improve under hAAT-rich conditions. Here, wound healing was examined in the presence of recombinant hAAT (hAAT^WT) and protease-inhibition-lacking hAAT (hAAT^CP). The impact of both hAAT forms was determined by an epithelial cell gap closure assay, and by excisional skin injuries via a microemulsion optimized for open wounds. Neutrophilic infiltration was examined after 8 h. According to results, both hAAT forms accelerated epithelial gap closure and excisional wound closure, particularly at early time points. Unlike dexamethasone-treated wounds, both resulted in closed borders at the 8-h time point. In untreated and hAAT^CP-treated wounds, leukocytic infiltrates were widespread, in hAAT^WT-treated wounds compartmentalized and in dexamethasone-treated wounds, scarce. Both hAAT forms decreased interleukin-1β and increased VEGF gene expression. In conclusion hAAT improves epithelial cell migration and outcomes of in vivo wounds irrespective of protease inhibition. While both forms of hAAT allow neutrophils to infiltrate, only native hAAT created discrete neutrophilic tissue clusters.

Enhanced Survival and Accelerated Perfusion of Skin Flap to Recipient Site Following Administration of Human α1-Antitrypsin in Murine Models

Objective: Skin flaps are routinely used in reconstructive surgery yet remain susceptible to ischemia and necrosis. Distant flaps require lengthy time to detach causing patient discomfort. Human α1-antitrypsin (hAAT) is a clinically available serum glycoprotein. hAAT was shown to support mature vessel formation and enhance tissue survival following ischemia-reperfusion injuries. The purpose of the presented study was to examine the effect of hAAT on skin flap survival and distant "tube" flap perfusion through its recipient site. Approach: Random-pattern skin flaps were performed on mice treated with clinical-grade hAAT using three unique routes of administration (transgenic, i.p. and s.c. infiltration); necrotic area and tissue perfusion were assessed. Blockade of vascular endothelial growth factor (VEGF) and nitric oxide synthase (NOS) were used to explore aspects of mechanism of action. A distant tube flap model was performed to examine time to perfusion. Results: hAAT-treated mice displayed approximately two-fold smaller necrotic flap areas versus controls across all hAAT administration routes. Flaps displayed greater perfusion as early as 3 days postsurgery (64.6% ± 4.0% vs. 43.7% ± 1.7% in controls; p = 0.007). hAAT-mediated flap survival was prominently NOS dependent, but only partially VEGF dependent. Finally, distant flaps treated with hAAT displayed significantly earlier perfusion versus controls (mean 9.6 ± 1.6 vs. 13.1 ± 1.0 days; p = 0.0005). Innovation: The established safety record of hAAT renders it an attractive candidate toward improving skin flap surgery outcomes, particularly during VEGF blockade. Conclusions: hAAT treatment enhances survival and accelerates perfusion of skin flaps in animal models in a NOS-dependent manner, partially circumventing VEGF blockade. Further mechanistic studies are required.

Abundant proteins in platelet-rich fibrin and their potential contribution to wound healing: An explorative proteomics study and review of the literature

Background/purpose

It is well-known that diverse types of blood proteins contribute to healing process via different mechanisms. Presence and potential involvements of blood-derived abundant proteins in the platelet-rich fibrin (PRF) to its regenerative capacity have not been sufficiently emphasized in the literature. The aim of this paper was to analyze the abundant proteome content of PRF and summarize previously reported effects of identified proteins on wound healing via a literature review.

Materials and methods

The PRF samples obtained from non-smoking, systemically healthy volunteers were subjected to 2D gel electrophoresis after extracting the proteins from fibrin matrices. All matching spots were excised from the gels and identified by MALDI TOF/TOF MS/MS analysis. A literature review was conducted to reveal possible contributions of identified proteins to wound healing.

Results

Totally, thirty-five blood proteins were commonly identified among all studied samples. These proteins included serine protease inhibitors, such as alpha-1-antitrypsin, alpha-1-antichymotrypsin, alpha-1-acid glycoprotein, inter-alpha-trypsin-inhibitor, protease C1 inhibitor, and complement proteins. In addition, abundant presence of immunoglobulin G was observed. The abundance of albumin, haptoglobin, ceruloplasmin vitronectin, fetuin-A, ficolin-3 and transthyretin was also detected.

Conclusion

The results of this study indicated that PRF abundantly contains blood-origin actors which were previously reported for their direct contribution to wound healing. Further studies exploring the protein content of PRF are needed to reveal its undisclosed potential roles in the healing process.

Endothelial cell regulation through epigenetic mechanisms: Depicting parallels and its clinical application within an intra-islet microenvironment

The intra-islet endothelial cells (ECs), the building blocks of islet microvasculature, govern a number of cellular and pathophysiological processes associated with the pancreatic tissue. These cells are key to the angiogenic process and essential for islet revascularization after transplantation. Understanding fundamental mechanisms by which ECs regulate the angiogenic process is important as these cells maintain and regulate the intra-islet environment facilitated by a complex signaling crosstalk with the surrounding endocrine cells. In recent years, many studies have demonstrated the impact of epigenetic regulation on islet cell development and function. This review will present an overview of the reports involving endothelial epigenetic mechanisms particularly focusing on histone modifications which have been identified to play a critical role in governing EC functions by modifying the chromatin structure. A better understanding of epigenetic mechanisms by which these cells regulate gene expression and function to orchestrate cellular physiology and pathology is likely to offer improved insights on the functioning and regulation of an intra-islet endothelial microvascular environment.

Point Mutation of a Non-Elastase-Binding Site in Human α1-Antitrypsin Alters Its Anti-Inflammatory Properties

Introduction

Human α1-antitrypsin (hAAT) is a 394-amino acid long anti-inflammatory, neutrophil elastase inhibitor, which binds elastase via a sequence-specific molecular protrusion (reactive center loop, RCL; positions 357-366). hAAT formulations that lack protease inhibition were shown to maintain their anti-inflammatory activities, suggesting that some attributes of the molecule may reside in extra-RCL segments. Here, we compare the protease-inhibitory and anti-inflammatory profiles of an extra-RCL mutation (cys232pro) and two intra-RCL mutations (pro357cys, pro357ala), to naïve [wild-type (WT)] recombinant hAAT, in vitro, and in vivo.

Methods

His-tag recombinant point-mutated hAAT constructs were expressed in HEK-293F cells. Purified proteins were evaluated for elastase inhibition, and their anti-inflammatory activities were assessed using several cell-types: RAW264.7 cells, mouse bone marrow-derived macrophages, and primary peritoneal macrophages. The pharmacokinetics of the recombinant variants and their effect on LPS-induced peritonitis were determined in vivo.

Results

Compared to WT and to RCL-mutated hAAT variants, cys232pro exhibited superior anti-inflammatory activities, as well as a longer circulating half-life, despite all three mutated forms of hAAT lacking anti-elastase activity. TNFα expression and its proteolytic membranal shedding were differently affected by the variants; specifically, cys232pro and pro357cys altered supernatant and serum TNFα dynamics without suppressing transcription or shedding.

Conclusion

Our data suggest that the anti-inflammatory profile of hAAT extends beyond direct RCL regions. Such regions might be relevant for the elaboration of hAAT formulations, as well as hAAT-based drugs, with enhanced anti-inflammatory attributes.

Alpha-1 Antitrypsin Investigations Using Animal Models of Emphysema

Animal models of disease help accelerate the translation of basic science discoveries to the bedside, because they permit experimental interrogation of mechanisms at relatively high throughput, while accounting for the complexity of an intact organism. From the groundbreaking observation of emphysema-like alveolar destruction after direct instillation of elastase in the lungs to the more clinically relevant model of airspace enlargement induced by chronic exposure to cigarette smoke, animal models have advanced our understanding of alpha-1 antitrypsin (AAT) function. Experimental in vivo models that, at least in part, replicate clinical human phenotypes facilitate the translation of mechanistic findings into individuals with chronic obstructive pulmonary disease and with AAT deficiency. In addition, unexpected findings of alveolar enlargement in various transgenic mice have led to novel hypotheses of emphysema development. Previous challenges in manipulating the AAT genes in mice can now be overcome with new transgenic approaches that will likely advance our understanding of functions of this essential, lung-protective serine protease inhibitor (serpin).

Intra-islet endothelial cell and β-cell crosstalk: Implication for islet cell transplantation

The intra-islet microvasculature is a critical interface between the blood and islet endocrine cells governing a number of cellular and pathophysiological processes associated with the pancreatic tissue. A growing body of evidence indicates a strong functional and physical interdependency of β-cells with endothelial cells (ECs), the building blocks of islet microvasculature. Intra-islet ECs, actively regulate vascular permeability and appear to play a role in fine-tuning blood glucose sensing and regulation. These cells also tend to behave as “guardians”, controlling the expression and movement of a number of important immune mediators, thereby strongly contributing to the physiology of islets. This review will focus on the molecular signalling and crosstalk between the intra-islet ECs and β-cells and how their relationship can be a potential target for intervention strategies in islet pathology and islet transplantation.

Context-Specific and Immune Cell-Dependent Antitumor Activities of α1-Antitrypsin

α1-antitrypsin (AAT), a circulating glycoprotein that rises during acute phase responses and healthy pregnancies, exhibits immunomodulatory properties in several T-cell-dependent immune pathologies. However, AAT does not directly interfere with T-cell responses; instead, it facilitates polarization of macrophages and dendritic cells towards M2-like and tolerogenic cells, respectively. AAT also allows NK cell responses against tumor cells, while attenuating DC-dependent induction of autoimmune NK cell activities. Since AAT-treated macrophages bear resemblance to cancer-promoting tumor-associated macrophages (TAMs), it became imperative to examine the possible induction of tumor permissive conditions by AAT. Here, AAT treatment is examined for its effect on tumor development, metastatic spread, and tumor immunology. Systemic AAT treatment of mice inoculated with B16-F10 melanoma cells resulted in significant inhibition of tumor growth and metastatic spread. Using NK cell-resistant RMA cells, we show that AAT interferes with tumor development in a CD8+ T-cell-dependent manner. Unexpectedly, upon analysis of tumor cellular composition, we identified functional tumor-infiltrating CD8+ T-cells alongside M1-like TAMs in AAT-treated mice. Based on the ability of AAT to undergo chemical modifications, we emulated conditions of elevated reactive nitrogen and oxygen species. Indeed, macrophages were stimulated by treatment with nitrosylated AAT, and IFNγ transcripts were significantly elevated in tumors extracted soon after ischemia-reperfusion challenge. These context-specific changes may explain the differential effects of AAT on immune responses towards tumor cells versus benign antigenic targets. These data suggest that systemically elevated levels of AAT may accommodate its physiological function in inflammatory resolution, without compromising tumor-targeting immune responses.

Xeno-Transplantation of macro-encapsulated islets and Pluripotent Stem Cell-Derived Pancreatic Progenitors without Immunosuppression

Islet transplantation effectively treats diabetes but relies on immune suppression and is practically limited by the number of cadaveric islets available. An alternative cellular source is insulin-producing cells derived from pluripotent cell sources. Three animal cohorts were used in the current study to evaluate whether an oxygen-providing macro-encapsulation device, 'βAIR', could function in conjunction with human embryonic stem cells (hESCs) and their derivatives. The first cohort received macro-encapsulated undifferentiated hESCs, a second cohort received hESCs differentiated to a pancreatic progenitor state with limited endocrine differentiation. A reference cohort received human islets. Macro-encapsulation devices were implanted subcutaneously and monitored for up to 4 months. Undifferentiated pluripotent stem cells did not form teratoma but underwent cell death following implantation. Human C-peptide (hC- peptide) was detectable in host serum one week after implantation for both other cohorts. hC-peptide levels decreasing over time but remained detectable up to the end of the study. Key factors associated with mature endocrine cells were observed in grafts recovered from cohorts containing islets and hESC-derivatives including C-peptide, insulin, glucagon and urocortin 3. We conclude that the 'βAIR' macroencapsulation device is compatible with both human islets and pluripotent derivatives, but has a limited capability of sustaining undifferentiated pluripotent cells.

Alpha-1 antitrypsin therapy is safe and well tolerated in children and adolescents with recent onset type 1 diabetes mellitus

BACKGROUND AND OBJECTIVES

Alpha-1 antitrypsin (AAT) has been shown to reduce pro-inflammatory markers and protect pancreatic islets from autoimmune responses in recent studies. Our aim was to evaluate its safety and tolerability in three different doses, in a pediatric population with recent onset type 1 diabetes mellitus (T1DM).

METHODS

A 37-wk prospective, open-label, phase I/II interventional trial, comprised of 24 recently diagnosed subjects (12 males; age 12.9 ± 2.4 yr), who received 18 infusions of 40, 60, or 80 mg/kg/dose high-purity, liquid, ready to use AAT over 28 wk (Glassia(®) ; Kamada Ltd., Ness Ziona, Israel).

PRIMARY OUTCOMES

safety and tolerability; secondary outcomes: glycemic control, C-peptide reserve, and autoantibody levels. Possible responders were defined as individuals with peak C-peptide that declined less than 7.5% below baseline.

RESULTS

No serious adverse events, diabetic ketoacidosis (DKA), or severe hypoglycemic episodes were reported. Adverse events were dose-independent and transient. Glycemic control parameters improved during the study in all groups, independent of dosage. Hemoglobin A1c (HbA1c) decreased from 8.43 to 7.09% (mean, p < 0.001). At the end of the study, 18 subjects (75%) had a peak C-peptide ≥0.2 pmol/mL. Eight subjects (33.3%) were considered possible responders and were characterized by shorter duration of T1DM at screening (54.5 ± 34.3 vs. 95.9 ± 45.7 d, p = 0.036) and greater decrease in their HbA1c during the study period (-2.94 ± 1.55 vs.-0.95 ± 1.83%, p = 0.016).

CONCLUSIONS

AAT treatment was safe and well tolerated in pediatric subjects with recently diagnosed autoimmune diabetes. Placebo-controlled studies with larger cohorts and dose range are warranted in order to assess efficacy in maintaining pancreatic beta cell reserve and glycemic control.

RNA-Seq Analysis Reveals Genes Underlying Different Disease Responses to Porcine Circovirus Type 2 in Pigs

Porcine circovirus type 2 (PCV2), an economically important pathogen, causes postweaning multisystemic wasting syndrome (PMWS) and other syndrome diseases collectively known as porcine circovirus-associated disease (PCVAD). Previous studies revealed breed-dependent differences in porcine susceptibility to PCV2; however, the genetic mechanism underlying different resistance to PCV2 infection remains largely unknown. In this study, we found that Yorkshire × Landrace (YL) pigs exhibited serious clinical features typifying PCV2 disease, while the Laiwu (a Chinese indigenous pig breed, LW) pigs showed little clinical symptoms of the disease during PCV2 infection. At 35 days post infection (dpi), the PCV2 DNA copy in YL pigs was significantly higher than that in LW pigs (P < 0.05). The serum level of IL-4, IL-6, IL-8, IL-12 and TGF-β1 in LW pigs and TNF-α in YL pigs increased significantly at the early infected stages, respectively; while that of IL-10 and IFN-γ in YL pigs was greatly increased at 35 dpi. RNA-seq analysis revealed that, at 35 dpi, 83 genes were up-regulated and 86 genes were down-regulated in the lung tissues of LW pigs, while in YL pigs, the numbers were 187 and 18, respectively. In LW pigs, the differentially expressed genes (DEGs) were mainly involved in complement and coagulation cascades, metabolism of xenobiotics by cytochrome P450, RIG-I-like receptor signaling and B cell receptor signaling pathways. Four up-regulated genes (TFPI, SERPNC1, SERPNA1, and SERPNA5) that are enriched in complement and coagulation cascades pathway were identified in the PCV2-infected LW pigs, among which the mRNA expression of SERPNA1, as well as three genes including TGF-β1, TGF-β2 and VEGF that are regulated by SERPNA1 was significantly increased (P < 0.05). We speculate that higher expression of SERPNA1 may effectively suppress excessive inflammation reaction and reduce the pathological degree of lung tissue in PCV2-infected pigs. Collectively, our findings indicate that the susceptibility to PCV2 infection depends on a genetic difference between LW and YL pigs, and SERPNA1 likely plays an important role in the resistance of LW pigs to PCV2 infection.

Alpha-1 Antitrypsin as a Therapeutic Agent for Conditions not Associated with Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin is a positive acute phase reactant whose serum level rises in response to inflammatory stress, presumably to balance pro-inflammatory processes. In addition to its serine protease inhibitory action, alpha-1 antitrypsin exhibits broader anti-inflammatory and immunomodulatory activity, and increasing its serum concentration by the administration of exogenous alpha-1 antitrypsin to above-normal levels potentially could be therapeutic in conditions other than alpha-1 antitrypsin deficiency. In vitro observations, studies in animal models and in some instances early human trials suggest that intravenous or inhaled alpha-1 antitrypsin has beneficial effects in type 1 diabetes, viral infections, graft-versus-host disease, cystic fibrosis, and alpha-1 antitrypsin-replete chronic obstructive pulmonary disease among others. While the results of pivotal clinical trials have not been reported to date, new indications for alpha-1 antitrypsin therapy are likely to emerge in the future based on currently available scientific data.

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.

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.

Mechanistic evidence in support of alpha1-antitrypsin as a therapeutic approach for type 1 diabetes

Utilizing endogenous molecules as a therapeutic approach is almost unequivocally superior to engineered or synthetic molecules. However, one rarely encounters an anti-inflammatory, cytoprotective, immunomodulatory and wound-healing molecule that has been available for use for decades. α1-antitrypsin (AAT), a circulating protein that rises more than 4-fold during acute-phase responses, has been administered for a rare genetic deficiency at large doses, for life. Aside from advances in insulin therapy, medical research in type 1 diabetes (T1D) has predominantly focused on autoimmunity--controlling the adaptive immune response. However, it is now appreciated that one may need to extend therapeutic targets to incorporate immune responses to cellular injury, as well as promote selective control over excessive inflammation and early tissue repair. Recent data suggest that tissue damage related to lung and renal ischemia-reperfusion injury, stroke, and ischemic heart disease is markedly reduced by AAT. AAT was also shown to protect pancreatic islet β cells at multiple levels. Unlike classic immunosuppressive and anti-inflammatory approaches, AAT exerts some antiviral and antibacterial activities. Based on these and other reports, AAT is under evaluation for treatment of T1D patients in multiple clinical trials. Initial results suggest that AAT therapy could potentially improve insulin production without adverse effects. Up to 50% of individuals displayed improved islet function. It is a rare occurrence in T1D research that a therapy is offered that holds a safety profile equal or superior to that of insulin alone. While placebo-controlled trials are ongoing, the mechanism(s) behind these favorable activities of AAT are still being explored.

Increased outer arm and core fucose residues on the N-glycans of mutated alpha-1 antitrypsin protein from alpha-1 antitrypsin deficient individuals

Alpha-1 antitrypsin (AAT) is the major physiological inhibitor of a range of serine proteases, and in the lung, it maintains a protease-antiprotease balance. AAT deficiency (AATD) is an autosomal co-dominant condition with the Z mutation being the most common cause. Individuals homozygous for Z (PiZZ) have low levels of circulating mutant Z-AAT protein leading to premature emphysematous lung disease. Extensive glycoanalysis has been performed on normal AAT (M-AAT) from healthy individuals and the importance of glycosylation in affecting the immune modulatory roles of AAT is documented. However, no glycoanalysis has been carried out on Z-AAT from deficient individuals to date. In this study, we investigate whether the glycans present on Z-AAT differ to those found on M-AAT from healthy controls. Plasma AAT was purified from 10 individuals: 5 AATD donors with the PiZZ phenotype and 5 PiMM healthy controls. Glycoanalysis was performed employing N-glycan release, exoglycosidase digestion and UPLC analysis. No difference in branched glycans was identified between AATD and healthy controls. However, a significant increase in both outer arm (α1-3) (p = 0.04) and core (α1-6) fucosylated glycans (p < 0.0001) was found on Z-AAT compared to M-AAT. This study has identified increased fucosylation on N-glycans of Z-AAT indicative of ongoing inflammation in AATD individuals with implications for early therapeutic intervention.

Pancreatic islet xenograft survival in mice is extended by a combination of alpha-1-antitrypsin and single-dose anti-CD4/CD8 therapy

Clinical pancreatic islet transplantation is under evaluation for the treatment of autoimmune diabetes, yet several limitations preclude widespread use. For example, there is a critical shortage of human pancreas donors. Xenotransplantation may solve this problem, yet it evokes a rigorous immune response which can lead to graft rejection. Alpha-1-antitrypsin (AAT), a clinically available and safe circulating anti-inflammatory and tissue protective glycoprotein, facilitates islet alloimmune-tolerance and protects from inflammation in several models. Here, we examine whether human AAT (hAAT), alone or in combination with clinically relevant approaches, achieves long-term islet xenograft survival. Rat-to-mouse islet transplantation was examined in the following groups: untreated (n = 6), hAAT (n = 6, 60-240 mg/kg every 3 days from day -10), low-dose co-stimulation blockade (anti-CD154/LFA-1) and single-dose anti-CD4/CD8 (n = 5-7), either as mono- or combination therapies. Islet grafting was accompanied by blood glucose follow-up. In addition, skin xenografting was performed in order to depict responses that occur in draining lymph nodes. According to our results hAAT monotherapy and hAAT/anti-CD154/LFA-1 combined therapy, did not delay rejection day (11-24 days untreated vs. 10-22 day treated). However, host and donor intragraft inflammatory gene expression was diminished by hAAT therapy in both setups. Single dose T-cell depletion using anti-CD4/CD8 depleting antibodies, which provided 14-15 days of reduced circulating T-cells, significantly delayed rejection day (28-52 days) but did not achieve graft acceptance. In contrast, in combination with hAAT, the group displayed significantly extended rejection days and a high rate of graft acceptance (59, 61, >90, >90, >90). In examination of graft explants, marginal mononuclear-cell infiltration containing regulatory T-cells predominated surviving xenografts. We suggest that temporal T-cell depletion, as in the clinically practiced anti-thymocyte-globulin therapy, combined with hAAT, may promote islet xenograft acceptance. Further studies are required to elucidate the mechanism behind the observed synergy, as well as the applicability of the approach for pig-to-human islet xenotransplantation.