α1-antitrypsin inhibits angiogenesis and tumor growth

Exploring the Therapeutic Potential of Elastase Inhibition in Age-Related Macular Degeneration in Mouse and Human

Abnormal turnover of the extracellular matrix (ECM) protein elastin has been linked to AMD pathology. Elastin is a critical component of Bruch's membrane (BrM), an ECM layer that separates the retinal pigment epithelium (RPE) from the underlying choriocapillaris. Reduced integrity of BrM's elastin layer corresponds to areas of choroidal neovascularization (CNV) in wet AMD. Serum levels of elastin-derived peptides and anti-elastin antibodies are significantly elevated in AMD patients along with the prevalence of polymorphisms of genes regulating elastin turnover. Despite these results indicating significant associations between abnormal elastin turnover and AMD, very little is known about its exact role in AMD pathogenesis. Here we report on results that suggest that elastase enzymes could play a direct role in the pathogenesis of AMD. We found significantly increased elastase activity in the retinas and RPE cells of AMD mouse models, and AMD patient-iPSC-derived RPE cells. A1AT, a protease inhibitor that inactivates elastase, reduced CNV lesion sizes in mouse models. A1AT completely inhibited elastase-induced VEGFA expression and secretion, and restored RPE monolayer integrity in ARPE-19 monolayers. A1AT also mitigated RPE thickening, an early AMD phenotype, in HTRA1 overexpressing mice, HTRA1 being a serine protease with elastase activity. Finally, in an exploratory study, examining archival records from large patient data sets, we identified an association between A1AT use, age and AMD risk. Our results suggest that repurposing A1AT may have therapeutic potential in modifying the progression to AMD.

Age-dependent transcriptional alterations in cardiac endothelial cells

Aging is a significant risk factor for cardiovascular disease. Despite the fact that endothelial cells play critical roles in cardiovascular function and disease, the molecular impact of aging on this cell population in many organ systems remains unknown. In this study, we sought to determine age-associated transcriptional alterations in cardiac endothelial cells. Highly enriched populations of endothelial cells (ECs) isolated from the heart, brain, and kidney of young (3 mo) and aged (24 mo) C57/BL6 mice were profiled for RNA expression via bulk RNA sequencing. Approximately 700 cardiac endothelial transcripts significantly differ by age. Gene set enrichment analysis indicated similar patterns for cellular pathway perturbations. Receptor-ligand comparisons indicated parallel alterations in age-affected circulating factors and cardiac endothelial-expressed receptors. Gene and pathway enrichment analyses show that age-related transcriptional response of cardiac endothelial cells is distinct from that of endothelial cells derived from the brain or kidney vascular bed. Furthermore, single-cell analysis identified nine distinct EC subtypes and shows that the Apelin Receptor-enriched subtype is reduced with age in mouse heart. Finally, we identify age-dysregulated genes in specific aged cardiac endothelial subtypes.

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.

The Multifaceted Effects of Alpha1-Antitrypsin on Neutrophil Functions

Neutrophils are the predominant immune cells in human blood possessing heterogeneity, plasticity and functional diversity. The activation and recruitment of neutrophils into inflamed tissue in response to stimuli are tightly regulated processes. Alpha1-Antitrypsin (AAT), an acute phase protein, is one of the potent regulators of neutrophil activation via both -protease inhibitory and non-inhibitory functions. This review summarizes our current understanding of the effects of AAT on neutrophils, illustrating the interplay between AAT and the key effector functions of neutrophils.

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.

Alpha-1-antitrypsin interacts with gp41 to block HIV-1 entry into CD4+ T lymphocytes

Background

Study of a clinic case reveals that alpha-1-antitrypsin (AAT) deficiency is related to CD4+ T cell count decline and AIDS progression, suggesting that AAT might be an endogenous inhibitor of HIV/AIDS. Previous study shows that AAT inhibits HIV-1 replication in infected host cells and the C-terminus fragment of AAT, VIRIP, interferes with HIV-1 infection. However, it is still unclear whether and how intact AAT inhibits HIV-1 infection. It is also unknown what the mechanism of AAT is and which critical step(s) are involved.

Results

In the present study, the C-terminus of AAT (C) was synthesized. C terminus-truncated AAT (ΔAAT) was also prepared by digesting AAT with metalloproteinase. Primary CD4+ T cells were then co-cultured with HIV-1 with the presence or absence of AAT/C/ΔAAT to detect cis-infection of HIV-1. The interaction between AAT/C/ΔAAT and gp120/gp41 was also measured. Meanwhile, HIV-1 reverse transcriptase activity and viral DNA integration were also detected in these lymphocytes. The results demonstrated that AAT and C, not ΔAAT, inhibited HIV-1 entry by directly interacting with gp41. Meanwhile, AAT, C and ΔAAT could not directly interfere with the steps of viral RNA reverse transcription and viral DNA integration.

Conclusion

AAT inhibits HIV-1 entry by directly interacting with gp41 through its C-terminus and thereby inhibits HIV-1 infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0751-2) contains supplementary material, which is available to authorized users.

Role of heparin and non heparin binding serpins in coagulation and angiogenesis: A complex interplay

Pro-coagulant, anti-coagulant and fibrinolytic pathways are responsible for maintaining hemostatic balance under physiological conditions. Any deviation from these pathways would result in hypercoagulability leading to life threatening diseases like myocardial infarction, stroke, portal vein thrombosis, deep vein thrombosis (DVT) and pulmonary embolism (PE). Angiogenesis is the process of sprouting of new blood vessels from pre-existing ones and plays a critical role in vascular repair, diabetic retinopathy, chronic inflammation and cancer progression. Serpins; a superfamily of protease inhibitors, play a key role in regulating both angiogenesis and coagulation. They are characterized by the presence of highly conserved secondary structure comprising of 3 β-sheets and 7-9 α-helices. Inhibitory role of serpins is modulated by binding to cofactors, specially heparin and heparan sulfate proteoglycans (HSPGs) present on cell surfaces and extracellular matrix. Heparin and HSPGs are the mainstay of anti-coagulant therapy and also have therapeutic potential as anti-angiogenic inhibitors. Many of the heparin binding serpins that regulate coagulation cascade are also potent inhibitors of angiogenesis. Understanding the molecular mechanism of the switch between their specific anti-coagulant and anti-angiogenic role during inflammation, stress and regular hemostasis is important. In this review, we have tried to integrate the role of different serpins, their interaction with cofactors and their interplay in regulating coagulation and angiogenesis.

Alpha 1 Antitrypsin Inhibits Dendritic Cell Activation and Attenuates Nephritis in a Mouse Model of Lupus

Systemic lupus erythematosus (SLE) is an autoimmune disorder with a worldwide distribution and considerable mortality and morbidity. Although the pathogenesis of this disease remains elusive, over-reactive dendritic cells (DCs) play a critical role in the disease development. It has been shown that human alpha-1 antitrypsin (hAAT) has protective effects in type 1 diabetes and rheumatoid arthritis mouse models. In the present study, we tested the effect of AAT on DC differentiation and functions, as well as its protective effect in a lupus-prone mouse model. We showed that hAAT treatment significantly inhibited LPS (TLR4 agonist) and CpG (TLR9 agonist) -induced bone-marrow (BM)-derived conventional and plasmacytoid DC (cDC and pDC) activation and reduced the production of inflammatory cytokines including IFN-I, TNF-α and IL-1β. In MRL/lpr mice, hAAT treatment significantly reduced BM-derived DC differentiation, serum autoantibody levels, and importantly attenuated renal pathology. Our results for the first time demonstrate that hAAT inhibits DC activation and function, and it also attenuates autoimmunity and renal damage in the MRL/lpr lupus model. These results imply that hAAT has a therapeutic potential for the treatment of SLE in humans.

Host protein C inhibitor inhibits tumor growth, but promotes tumor metastasis, which is closely correlated with hypercoagulability

INTRODUCTION

Protein C inhibitor (PCI), a member of the serine protease inhibitor family, is expressed in various human tissues, including liver and kidneys. In the plasma, PCI physiologically inhibits an anticoagulant serine protease, activated protein C (APC). PCI expressed by cancer cells suppresses tumor invasion by inhibiting urokinase-type plasminogen activator, and inhibits tumor growth and metastasis, which are independent of its protease-inhibitory activity. In the present study, we clarified the effects of host PCI on growth and metastasis of B16 melanoma (B16) cells by comparing between wild-type mice and mice transgenic for human PCI gene (hPCI-TG), which have a tissue distribution of PCI similar to that observed in humans.

MATERIALS AND METHODS

Growth of intracutaneously-injected B16 cells was evaluated by measuring the tumor volume, and metastatic behavior of intravenously-injected B16 cells by counting the number of metastatic lung nodules.

RESULTS

Growth of intracutaneously injected B16 cells was significantly faster in wild-type mice than in hPCI-TG mice; however, hPCI-TG mice developed more metastatic nodules of B16 cells in the lungs. Immunohistochemical analysis using anti-mouse fibrinogen antibody revealed more fibrin deposition in the lung in hPCI-TG mice than in wild-type mice. Furthermore, the more invasive behavior observed in hPCI-TG mice was reduced by rabbit anti-human PCI IgG, APC, or soluble TM administration for 3 consecutive days including the day that B16 cells were injected.

CONCLUSIONS

Our results suggest that like PCI expressed in tumor cells, host PCI also inhibits tumor growth, but host PCI promotes tumor metastasis via its procoagulant properties.

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.

Regulation of autophagy by α1-antitrypsin: "a foe of a foe is a friend"

Autophagy is involved in both the cell protective and the cell death process but its mechanism is largely unknown. The present work unravels a novel intracellular mechanism by which the serpin α1-antitrypsin (AAT) acts as a novel negative regulator of autophagic cell death. For the first time, the role of intracellularly synthesized AAT, other than in liver cells, is demonstrated. Autophagic cell death was induced by N-α-tosyl-L-phenylalanine chloromethyl ketone (TPCK) and tamoxifen. By utilizing a fluorescently tagged TPCK analog, AAT was "fished out" (pulled out) as a TPCK intracellular protein target. The interaction was further verified by competition binding experiments. Both inducers caused downregulation of AAT expression associated with activation of trypsin-like proteases. Furthermore, silencing AAT by siRNA induced autophagic cell death. Moreover, AAT administration to cultured cells prevented autophagic cell death. This new mechanism could have implications in the treatment of diseases by the regulation of AAT levels in which autophagy has a detrimental function. Furthermore, the results imply that the high synthesis of endogenous AAT by cancer cells could provide a novel resistance mechanism of cancer against autophagic cell death.

α1-Antitrypsin modifies general NK cell interactions with dendritic cells and specific interactions with islet β-cells in favor of protection from autoimmune diabetes

The autoimmune destruction of pancreatic β-cells is the hallmark of type 1 diabetes (T1D). Failure of anti-CD3 antibodies to provide long-lasting reversal of T1D and the expression of an NK cell ligand on β-cells suggest that NK cells play a role in disease pathogenesis. Indeed, killing of β-cells by NK cells has been shown to occur, mediated by activation of the NK cell activating receptor, NKp46. α1-antitrypsin (AAT), an anti-inflammatory and immunomodulatory glycoprotein, protects β-cells from injurious immune responses and is currently evaluated as a therapeutic for recent onset T1D. While isolated T lymphocytes are not inhibited by AAT, dendritic cells (DCs) become tolerogenic in its presence and other innate immune cells become less inflammatory. Yet a comprehensive profile of NK cell responses in the presence of AAT has yet to be described. In the present study, we demonstrate that AAT significantly reduces NK cell degranulation against β-cells, albeit in the whole animal and not in isolated NK cell cultures. AAT-treated mice, and not isolated cultured β-cells, exhibited a marked reduction in NKp46 ligand levels on β-cells. In related experiments, AAT-treated DCs exhibited reduced inducible DC-expressed IL-15 levels and evoked a weaker NK cell response. NK cell depletion in a T1D mouse model resulted in improved β-cell function and survival, similar to the effects observed by AAT treatment alone; nonetheless, the two approaches were non-synergistic. Our data suggest that AAT is a selective immunomodulator that retains pivotal NK cell responses, while diverting their activities away from islet β-cells. This article is protected by copyright. All rights reserved.

Acute-Phase Protein α1-Antitrypsin—A Novel Regulator of Angiopoietin-like Protein 4 Transcription and Secretion

The angiopoietin-like protein 4 (angptl4, also known as peroxisome proliferator–activated receptor [PPAR]γ–induced angiopoietin-related protein) is a multifunctional protein associated with acute-phase response. The mechanisms accounting for the increase in angptl4 expression are largely unknown. This study shows that human α1-antitrypsin (A1AT) upregulates expression and release of angplt4 in human blood adherent mononuclear cells and in primary human lung microvascular endothelial cells in a concentration- and time-dependent manner. Mononuclear cells treated for 1 h with A1AT (from 0.1 to 4 mg/ml) increased mRNA of angptl4 from 2- to 174-fold, respectively, relative to controls. In endothelial cells, the maximal effect on angptl4 expression was achieved at 8 h with 2 mg/ml A1AT (11-fold induction versus controls). In 10 emphysema patients receiving A1AT therapy (Prolastin), plasma angptl4 levels were higher relative to patients without therapy (nanograms per milliliter, mean [95% confidence interval] 127.1 [99.5–154.6] versus 76.8 [54.8–98.8], respectively, p = 0.045) and correlated with A1AT levels. The effect of A1AT on angptl4 expression was significantly diminished in cells pretreated with a specific inhibitor of ERK1/2 activation (UO126), irreversible and selective PPARγ antagonist (GW9662), or genistein, a ligand for PPARγ. GW9662 did not alter the ability of A1AT to induce ERK1/2 phosphorylation, suggesting that PPARγ is a critical mediator in the A1AT-driven angptl4 expression. In contrast, the forced accumulation of HIF-1α, an upregulator of angptl4 expression, enhanced the effect of A1AT. Thus, acute-phase protein A1AT is a physiological regulator of angptl4, another acute-phase protein.

Serum concentration of alpha-1 antitrypsin is significantly higher in colorectal cancer patients than in healthy controls

Background

The association between alpha-1 antitrypsin (AAT) deficiency and colorectal cancer (CRC) is currently controversial. The present study compares AAT serum concentrations and gene frequencies between a group of CRC patients and a control group of healthy unrelated people (HUP).

Methods

267 CRC subjects (63% males, 72 ± 10 years old) were enlisted from a Hospital Clinic setting in Asturias, Spain. The HUP group comprised 327 subjects (67% males, mean age 70 ± 7.5 years old) from the same geographical region. Outcome measures were AAT serum concentrations measured by nephelometry, and AAT phenotyping characterization by isoelectric focusing.

Results

Significantly higher serum concentrations were found among CRC (208 ± 60) than in HUP individuals (144 ± 20.5) (p = 0.0001). No differences were found in the phenotypic distribution of the Pi*S and Pi*Z allelic frequencies (p = 0.639), although the frequency of Pi*Z was higher in CRC (21%) than in HUP subjects (15%).

Conclusions

The only statistically significant finding in this study was the markedly higher AAT serum concentrations found in CRC subjects compared with HUP controls, irrespective of whether their Pi* phenotype was normal (Pi*MM) or deficient (Pi*MS, Pi*MZ and Pi*SZ). Although there was a trend towards the more deficient Pi* phenotype the more advanced the tumor, the results were inconclusive due to the small sample size. Consequently, more powerful studies are needed to reach firmer conclusions on this matter.

Antiangiogenic and antineuroinflammatory effects of kallistatin through interactions with the canonical Wnt pathway

Kallistatin is a member of the serine proteinase inhibitor superfamily. Kallistatin levels have been shown to be decreased in the vitreous while increased in the circulation of patients with diabetic retinopathy (DR). Overactivation of the Wnt pathway is known to play pathogenic roles in DR. To investigate the role of kallistatin in DR and in Wnt pathway activation, we generated kallistatin transgenic (kallistatin-TG) mice overexpressing kallistatin in multiple tissues including the retina. In the oxygen-induced retinopathy (OIR) model, kallistatin overexpression attenuated ischemia-induced retinal neovascularization. In diabetic kallistatin-TG mice, kallistatin overexpression ameliorated retinal vascular leakage, leukostasis, and overexpression of vascular endothelial growth factor and intracellular adhesion molecule. Furthermore, kallistatin overexpression also suppressed Wnt pathway activation in the retinas of the OIR and diabetic models. In diabetic Wnt reporter (BAT-gal) mice, kallistatin overexpression suppressed retinal Wnt reporter activity. In cultured retinal cells, kallistatin blocked Wnt pathway activation induced by high glucose and by Wnt ligand. Coprecipitation and ligand-binding assays both showed that kallistatin binds to a Wnt coreceptor LRP6 with high affinity (Kd = 4.5 nmol/L). These observations suggest that kallistatin is an endogenous antagonist of LRP6 and inhibitor of Wnt signaling. The blockade of Wnt signaling may represent a mechanism for its antiangiogenic and antineuroinflammatory effects.

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

Pancreatic islets are a highly vascularized entity, and their transplantation into diabetic individuals requires optimal revascularization. In addition, β-cells in islets are extremely sensitive to inflammation. α-1-Antitrypsin (AAT), a circulating serine-protease inhibitor that is available for clinical use as an affinity-purified human product, has been shown to protect islets from graft failure in mouse transplantation models and to achieve readily vascularized islet grafts. AAT is known to induce vascular endothelial growth factor (VEGF) expression and release, as well as protect from proteolytic cleavage of VEGF by elastase, promote viability of endothelial cells, and enhance migration of myocytes. Our aim was to examine whether AAT enhances vasculogenesis toward islet grafts. We employed Matrigel-islet plugs as means to introduce islets in an explantable isolated compartment and examined vessel formation, vessel maturation, and inflammatory profile of explants 9 days after implantation. Also, we examined primary epithelial cell grafts that were prepared from lungs of mice that are transgenic for human AAT. In addition, aortic ring sprouting assay was performed, and HUVEC tube formation assays were studied in the presence of AAT. Our findings indicate that islet grafts exhibit mature vessels in the presence of AAT, as demonstrated by morphology, as well as expression of endothelial CD31, smooth muscle actin (SMA), and von Willebrand factor (vWF). Epithelial cells that express human AAT achieved a similar positive outcome. Aortic ring sprouting was enhanced in AAT-treated cultures and also in cultures that contained primary epithelial cells from human AAT transgenic animals in the absence of added AAT. According to the tube formation assay, HUVECs exhibited superior responses in the presence of AAT. We conclude that vasculogenesis toward islet grafts is enhanced in the presence of AAT. Together with the remarkable safety profile of AAT, the study supports its use in the relevant clinical setups.

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.

S100A9, GIF and AAT as potential combinatorial biomarkers in gastric cancer diagnosis and prognosis

PURPOSE

We have mined the gastric fluid proteome for potential gastric cancer (GC) biomarkers that may enhance disease detection and facilitate prognostic monitoring.

EXPERIMENTAL DESIGN

In biomarker discovery, a total of 12 patient gastric fluid samples (stages I, III, IV and gastritis) were analysed by 2DE for expression changes that correlated with GC status or disease progression. Gastric fluid proteins showing differential expression with GC were identified by MALDI-TOF/TOF MS as putative biomarkers. Levels of these potential biomarker candidates were independently validated by Western blotting in further 60 gastritis and GC patients. A targeted approach that recruits biomarker candidates for panel consideration was adopted to test if two or more biomarkers in combination improved diagnostic power.

RESULTS

From the 15 differentially regulated proteins identified, expression levels of S100A9, GIF and AAT in the gastric fluid clearly correlated with GC status. S100A9/AAT (AUC = 0.81) and S100A9/GIF (AUC = 0.92) were revealed as promising biomarker pairs for early GC diagnosis and disease monitoring, respectively.

CONCLUSION AND CLINICAL RELEVANCE

Early diagnosis, accurate staging and constant disease monitoring remain the prerequisites for effective treatment against GC. As current biomarkers like CA19-9 and carcinoembryonic antigen (CEA) lack sensitivity and specificity, there is a pressing need for novel GC detection and monitoring methods. To this end, S100A9, GIF and AAT from the gastric fluid may significantly augment existing methods of GC detection and monitoring, and eliminate the need for invasive tissue biopsies.

Assessment of the clinical significance of antigenic and functional levels of α1-proteinase inhibitor (α1-Pi) in infiltrating ductal breast carcinomas

OBJECTIVES

To determine the clinical significance of α1-proteinase inhibitor (α1-Pi) in infiltrating ductal breast carcinoma patients.

DESIGN AND METHODS

Serum levels of α1-Pi, tryptic specific inhibitory capacity and α1-Pi circulating immune complexes were determined using radial immunodiffusion, BAPNA assays and ELISA, respectively. 2-DE-MS and immunohistochemistry were performed to examine α1-Pi protein expression.

RESULTS

A decreased serum level of α1-Pi was found among breast cancer patients in comparison to controls. In addition, we found a significantly decreased mean level of α1-Pi in the node metastatic group when compared to node negative patients. However, the functional activity of the inhibitor did not decrease proportionately. Through 2-DE analyses, a differential expression of α1-Pi isoforms according to tumor stage and node metastatic development was found.

CONCLUSIONS

Both α1-Pi levels and specific activity could be a source of complementary clinical information and may provide useful information for a better understanding of the mechanisms of metastasis.

Human cornea proteome: identification and quantitation of the proteins of the three main layers including epithelium, stroma, and endothelium

Diseases of the cornea are common and refer to conditions like infections, injuries and genetic defects. Morphologically, many corneal diseases affect only certain layers of the cornea and separate analysis of the individual layers is therefore of interest to explore the basic molecular mechanisms involved in corneal health and disease. In this study, the three main layers including, the epithelium, stroma and endothelium of healthy human corneas were isolated. Prior to analysis by LC-MS/MS the proteins from the different layers were either (i) separated by SDS-PAGE followed by in-gel trypsinization, (ii) in-solution digested without prior protein separation or, (iii) in-solution digested followed by cation exchange chromatography. A total of 3250 unique Swiss-Prot annotated proteins were identified in human corneas, 2737 in the epithelium, 1679 in the stroma, and 880 in the endothelial layer. Of these, 1787 proteins have not previously been identified in the human cornea by mass spectrometry. In total, 771 proteins were quantified, 157 based on in-solution digestion and 770 based on SDS-PAGE separation followed by in-gel digestion of excised gel pieces. Protein analysis showed that many of the identified proteins are plasma proteins involved in defense responses.

Curcumin inhibits tumor proliferation induced by neutrophil elastase through the upregulation of α1-antitrypsin in lung cancer

Lung carcinogenesis is a complex process in an unregulated inflammatory environment. Curcumin has been extensively investigated as a multi-target anti-tumor and anti-inflammation compound. In this paper, we demonstrate a novel inflammation-related mechanism for curcumin-induced inhibition of lung tumor growth. We found that neutrophil elastase, an important regulator of inflammatory processes, directly triggered tumor cell proliferation in human lung adenocarcinoma A549 cells, and curcumin could completely suppress the excess tumor proliferation induced by neutrophil elastase. α1-antitrypsin is synthesized by tumor cells and is the natural inhibitor of neutrophil elastase. We found that curcumin counteracted the decrease of α1-antitrypsin induced by neutrophil elastase by inducing the promoter activity of α1-antitrypsin and promoting its expression in A549 cells. The inhibition of neutrophil elastase-induced proliferation by curcumin was dependent on the PI3K/Akt pathway. Knockdown of α1-antitrypsin by siRNA further enhanced the tumor cell proliferation induced by neutrophil elastase and significantly blocked the anti-proliferation effect of curcumin against neutrophil elastase. Curcumin remarkably inhibited the primary tumor growth of Lewis lung carcinoma (LLC) in C57BL/6 mice. We further showed that curcumin upregulated the level of α1-antitrypsin in primary tumor tissue by promoting its local expression, and the protein level of neutrophil elastase in tumor tissue was obviously decreased in mice treated with curcumin. Overall, our results suggest that neutrophil elastase and α1-antitrypsin play important roles in modulating lung tumor proliferation in inflammatory microenvironment and curcumin inhibits neutrophil elastase-induced tumor proliferation via upregulating α1-antitrypsin expression in vitro and in vivo.

Alpha-1-antitrypsin monotherapy reduces graft-versus-host disease after experimental allogeneic bone marrow transplantation

Acute graft-versus-host disease (GvHD) is a major complication that prevents successful outcomes after allogeneic bone marrow transplantation (BMT), an effective therapy for hematological malignancies. Several studies demonstrate that donor T cells and host antigen-presenting cells along with several proinflammatory cytokines are required for the induction of GvHD and contribute to its severity. Increasing evidence demonstrates that human serum-derived αalpha-1- anti-trypsin (AAT) reduces production of proinflammatory cytokines, induces anti-inflammatory cytokines, and interferes with maturation of dendritic cells. Using well-characterized mouse models of BMT, we have studied the effects of AAT on GvHD severity. Administration of AAT early after BMT decreased mortality in three models of GvHD and reduced serum levels of proinflammatory cytokines in the allogeneic recipients compared with vehicle (albumin) treated animals. AAT treatment reduced the expansion of alloreactive T effector cells but enhanced the recovery of T regulatory T cells, (Tregs) thus altering the ratio of donor T effector to T regulatory cells in favor of reducing the pathological process. However, despite altering the ratio in vivo, AAT had no direct effects on either the donor T effector cells or T regulatory cells Tregs in vitro. In contrast, AAT suppressed LPS-induced in vitro secretion of proinflammatory cytokines such as TNF-α and IL-1β, enhanced the production of the anti-inflammatory cytokine IL-10, and impaired NF-κB translocation in the host dendritic cells. In light of its long history of safety in humans, these findings suggest that administration of AAT represents a novel unique and viable strategy to mitigate clinical GvHD.

Mesenchymal stem cells as vehicles for targeted delivery of anti-angiogenic protein to solid tumors

BACKGROUND

Inhibition of tumor-induced angiogenesis may restrict tumor growth and metastasis. Long-term systemic delivery of angiogenic inhibitors is associated with toxicity, as well as other severe side-effects. The utility of cells as vehicles for gene therapy to deliver therapeutic molecules has been suggested to represent an efficient approach. Mesenchymal stem cells (MSCs) exhibit a tropism to cancer tissue, and may serve as a cellular delivery vehicle and a local producer of anti-angiogenic agents.

METHODS

In the present study, we attempted to assess production of the transgene, α1-antitrypsin (AAT), in lentivirus-transduced human MSCs and its cytotoxicity against human umbilical cord vein endothelial cells (HUVEC). The secreted protein from these effector cells was determined by an enzyme-linked immunosorbent assay. The cytotoxicity of hMSCs that overexpress the human AAT gene against HUVEC was evaluated with an apoptotic assay.

RESULTS

Lentivirus-transduced hMSCs produced functional AAT and displayed much higher cytotoxicity against HUVEC than untransduced hMSCs. Moreover, AAT secreted from transduced hMSCs significantly inhibited HUVEC proliferation compared to untransduced hMSCs. The data obtained demonstrate for the first time that genetically modified hMSCs released abundant and functional AAT that caused obvious cytotoxicity to HUVEC.

CONCLUSIONS

hMSC may serve as an effective platform for the targeted delivery of therapeutic proteins to cancer sites.

Alpha1-antitrypsin deficiency carriers, serum alpha 1-antitrypsin concentration, and non-small cell lung cancer survival

INTRODUCTION

Although the association between alpha 1-antitrypsin deficiency (α₁ATD) carriers and lung cancer risk has been found, the effects of α₁ATD carriers and serum alpha 1-antitrypsin (α₁AT) concentration on non-small cell lung cancer (NSCLC) survival remained unclear.

METHODS

Patients were selected from the Epidemiology and Genetics of Lung Cancer Study at Mayo Clinic with the criteria of (1) primary NSCLC diagnosis and (2) available α₁ATD carrier status tested by isoelectric focusing serum α₁AT concentration by immunonephelometry. The effects of carrier status and serum α₁AT concentration on survival were evaluated by Cox proportional hazards models with (1) a landmark approach, where overall survival was defined from the time of blood draw to death from any cause and (2) included only patients with blood draw time before initial treatment.

RESULTS

One thousand three hundred twenty-one patients were included in this study, with 179 α₁ATD carriers and 1142 noncarriers. No differences in overall survival by α₁ATD carrier status were found (adjusted hazard ratio [AHR]: 0.98; 95% confidence interval [CI]: 0.82-1.18). Nevertheless, serum α₁AT concentration was significantly associated with survival among all patients in the landmark model (AHR per 50 mg/dl increments: 1.15; 95% CI: 1.10-1.20) and among patients whose blood was drawn for serum α₁AT level assessment before any treatment (AHR per 50 mg/dl increments: 1.44; 95% CI: 1.21-1.71).

CONCLUSIONS

Being an α₁ATD carrier had no significant effect on NSCLC survival. The increased serum α₁AT concentration was a poor prognosis marker for NSCLC, regardless of carrier status.

Blocking the Wnt pathway, a unifying mechanism for an angiogenic inhibitor in the serine proteinase inhibitor family

The Wnt pathway regulates multiple biological and pathological processes including angiogenesis and inflammation. Here we identified a unique inhibitor of the Wnt pathway, SERPINA3K, a serine proteinase inhibitor with anti-inflammatory and angiogenic activities. SERPINA3K blocked the Wnt pathway activation induced by a Wnt ligand and by diabetes. Coprecipitation and ligand binding assay showed that SERPINA3K binds to low-density lipoprotein receptor-like protein 6 (LRP6) with a K(d) of 10 nM, in the range of its physiological concentration in the retina. Under the same conditions, SERPINA3K did not bind to the frizzled (Fz) receptor or low-density lipoprotein receptor. Further, SERPINA3K bound to LRP6 at the extracellular domain and blocked its dimerization with the Fz receptor induced by a Wnt ligand. The antagonizing activity of SERPINA3K to LRP6 was further confirmed by Xenopus axis duplication assay. These results suggest that SERPINA3K is a high-affinity, endogenous antagonist of LRP6. The blockade of Wnt signaling may represent a unifying mechanism for the anti-inflammatory and anti-angiogenic effects of SERPINA3K.

α1-Antitrypsin deficiency: best clinical practice

α1-Antitrypsin (AAT), a 52 kDa plasma protein, is produced mainly in the liver. It is the most abundant circulating serine proteinase inhibitor (serpin). It has also previously been called protease inhibitor to reflect its function as a general inhibitor of serine proteases. Its main physiological role is to inhibit neutrophil elastase and it contributes to the innate immune system as an anti-inflammatory protein. Severe AAT deficiency is most prevalent in northern Europeans affecting about 1 in 3000 of the population. AAT deficiency predisposes individuals who smoke to developing pulmonary emphysema in the fourth–fifth decade of adult life and to childhood cirrhosis in about 10% of cases, with the initial presentation being prolonged neonatal jaundice. The mean interval from presentation with symptoms to diagnosis in adults is about 8 years. The condition is under-recognised and under-diagnosed. The only effective current treatment for the severe liver disease that occurs in childhood currently is liver transplantation. Replacement therapy with purified AAT from human plasma is being used in clinical practice for the lung disease though it is not known whether this influences the outcome of this chronic condition. The liver pathology arises from intracellular polymerisation of mutant protein, and attenuation of polymerisation is a potential target for therapy.

Mechanism of alpha-1 antitrypsin endocytosis by lung endothelium

The integrity of lung alveoli is maintained by proper circulating levels of alpha-1 antitrypsin (A1AT). Next to cigarette smoking, A1AT deficiency is a major risk factor for lung emphysema development. We recently reported that in addition to neutralizing neutrophil elastases in the extracellular compartment, A1AT is internalized by lung endothelial cells and inhibits apoptosis. We hypothesized that the intracellular uptake of A1AT by endothelial cells may be required for its protective function; therefore, we studied the mechanisms of A1AT internalization by primary rat lung microvascular endothelial cells and the effect of cigarette smoke on this process both in vitro and in vivo (in mice). Purified A1AT was taken up intracellularly by endothelial cells in a time-dependent, dose-dependent, and conformer-specific manner and was detected in the cytoplasm of endothelial cells of nondiseased human lung sections. Despite a critical role for caveoli in endothelial cell endocytosis in general, specific inhibition of clathrin-mediated, but not caveoli-mediated, endocytosis profoundly decreased A1AT internalization and reversed the A1AT's antiapoptotic action. Further more, A1AT associated with clathrin heavy chains, but not with caveolin-1 in the plasma membrane fraction of endothelial cells. Interestingly, cigarette smoke exposure significantly inhibited A1AT uptake both in endothelial cells and in the mouse lung and altered the intracellular distribution of clathrin heavy chains. Our results suggest that clathrin-mediated endocytosis regulates A1AT intracellular function in the lung endothelium and may be an important determinant of the serpin's protection against developing cigarette smoke-induced emphysema.

Alpha-1-antitrypsin is an endogenous inhibitor of proinflammatory cytokine production in whole blood

Several observations suggest endogenous suppressors of inflammatory mediators are present in human blood. alpha-1-Antitrypsin (AAT) is the most abundant serine protease inhibitor in blood, and AAT possesses anti-inflammatory activity in vitro and in vivo. Here, we show that in vitro stimulation of whole blood from persons with a genetic AAT deficiency resulted in enhanced cytokine production compared with blood from healthy subjects. Using whole blood from healthy subjects, dilution of blood with RPMI tissue-culture medium, followed by incubation for 18 h, increased spontaneous production of IL-8, TNF-alpha, IL-1 beta, and IL-1R antagonist (IL-1Ra) significantly, compared with undiluted blood. Dilution-induced cytokine production suggested the presence of one or more circulating inhibitors of cytokine synthesis present in blood. Serially diluting blood with tissue-culture medium in the presence of cytokine stimulation with heat-killed Staphylococcus epidermidis (S. epi) resulted in 1.2- to 55-fold increases in cytokine production compared with S. epi stimulation alone. Diluting blood with autologous plasma did not increase the production of IL-8, TNF-alpha, IL-1 beta, or IL-1Ra, suggesting that the endogenous, inhibitory activity of blood resided in plasma. In whole blood, diluted and stimulated with S. epi, exogenous AAT inhibited IL-8, IL-6, TNF-alpha, and IL-1 beta significantly but did not suppress induction of the anti-inflammatory cytokines IL-1Ra and IL-10. These ex vivo and in vitro observations suggest that endogenous AAT in blood contributes to the suppression of proinflammatory cytokine synthesis.

Serological proteomics of gastritis: degradation of apolipoprotein A-I and alpha1-antitrypsin is a common response to inflammation irrespective of Helicobacter pylori infection

Proteomic technology was employed to analyze serum samples from healthy subjects (10 cases) and gastritis patients with negative and positive Helicobacter pylori (Hp) infection (15 cases each). The serum proteins were separated by two-dimensional (2-D) gel electrophoresis and analyzed by a computer-aided program. The altered proteins in expression were then identified by mass spectrometry and validated by Western blotting. Compared to those in normal control, proteins in at least six areas of 2-D gels were found to significantly increase their expression levels in both Hp-negative and Hp-positive serum samples. These proteins were identified by mass peptide fingerprinting and confirmed by Western blotting to be the truncated or cleaved protein fragments of apolipoprotein A-I and alpha-1 antitrypsin, two well-known acute-phase proteins. We conclude that the degradation or metabolization of acute-phase proteins, apolipoprotein A-I, and alpha1-antitrypsin, is a common response to gastric inflammation irrespective of Hp infection.

Endometrial carcinoma biomarker discovery and verification using differentially tagged clinical samples with multidimensional liquid chromatography and tandem mass spectrometry

The utility of differentially expressed proteins discovered and identified in an earlier study (DeSouza, L., Diehl, G., Rodrigues, M. J., Guo, J., Romaschin, A. D., Colgan, T. J., and Siu, K. W. M. (2005) Search for cancer markers from endometrial tissues using differentially labeled tags iTRAQ and cleavable ICAT with multidimensional liquid chromatography and tandem mass spectrometry. J. Proteome Res. 4, 377-386) to discriminate malignant and benign endometrial tissue samples was verified in a 40-sample iTRAQ (isobaric tags for relative and absolute quantitation) labeling study involving normal proliferative and secretory samples and Types I and II endometrial cancer samples. None of these proteins had the sensitivity and specificity to be used individually to discriminate between normal and cancer samples. However, a panel of pyruvate kinase, chaperonin 10, and alpha1-antitrypsin achieved the best results with a sensitivity, specificity, predictive value, and positive predictive value of 0.95 each in a logistic regression analysis. In addition, three new potential markers were discovered, whereas two other proteins showed promising trends but were not detected in sufficient numbers of samples to permit statistical validation. Differential expressions of some of these candidate biomarkers were independently verified using immunohistochemistry.

Similarities of ordered gene lists

MOTIVATION

Many applications of microarray technology in clinical cancer studies aim at detecting molecular features for refined diagnosis. In this paper, we follow an opposite rationale: we try to identify common molecular features shared by phenotypically distinct types of cancer using a meta-analysis of several microarray studies. We present a novel algorithm to uncover that two lists of differentially expressed genes are similar, even if these similarities are not apparent to the eye. The method is based on the ordering in the lists.

RESULTS

In a meta-analysis of five clinical microarray studies we were able to detect significant similarities in five of the ten possible comparisons of ordered gene lists. We included studies, where not a single gene can be significantly associated to outcome. The detection of significant similarities of gene lists from different microarray studies is a novel and promising approach. It has the potential to improve upon specialized cancer studies by exploring the power of several studies in one single analysis. Our method is complementary to previous methods in that it does not rely on strong effects of differential gene expression in a single study but on consistent ones across multiple studies.

Mass spectrometric proteomics profiles ofin vivo tumor secretomes: Capillary ultrafiltration sampling of regressive tumor masses

Identification of in vivo secreted peptides/proteins (secretomes) in tumor masses has the potential to provide important biomarkers and therapeutic targets for cancer therapy. However, limitations of existing technologies have made obtaining these secretomes for analysis extremely difficult. Here we employed an in vivo sampling technique using capillary ultrafiltration (CUF) probes to collect secretomes directly from tumor masses. Mass spectrometric proteomics approaches were then used to identify the tumor secretomes. A UV-induced skin fibrosarcoma cell line (UV-2240) was subcutaneously injected into C3H/NeH mice, resulting in tumor masses that initially progressed, then regressed and eventually eradicated. We then implanted CUF probes into tumor masses at the progressive and regressive stage. Five secreted proteins (cyclophilin-A, S100A4, profilin-1, thymosin beta 4 and 10), previously associated with tumor progression, were identified from tumor masses at the progressive stage. Five secreted proteins including three protease inhibitors (fetuin-A, alpha-1 antitrypsin 1-6, and contrapsin) were identified from tumor masses at the regressive stage. The technique involving CUF probes linked to mass spectrometric proteomics reinforces systems biology studies of cell-cell interactions and is potentially applicable to the discovery of in vivo biomarkers in human disease.

Antiangiogenic antithrombin induces global changes in the gene expression profile of endothelial cells

Antithrombin, a serpin family protease inhibitor crucial to hemostasis, acquires antiangiogenic properties on undergoing conformational alterations induced by limited proteolysis or elevated temperature. To better understand the biochemical mechanisms underlying antithrombin antiangiogenic activity, we did genome-wide expression profiling, coupled with quantitative reverse transcription-PCR, Northern blot, and Western blot analyses, to characterize the gene expression patterns that are induced by antiangiogenic antithrombin in cultured primary human umbilical vein endothelial cells. Overall, 35 genes with significantly increased expression and 93 genes with significantly reduced expression (> or =2-fold changes) due to antiangiogenic antithrombin treatment were identified. More than half of the down-regulated genes have well-established proangiogenic functions in endothelial cells, including cell-surface and matrix proteoglycans (e.g., perlecan, biglycan, and syndecans 1 and 3) and mitogenesis-related signaling proteins (e.g., mitogen-activated protein kinase 3, signal transducers and activators of transcription 2, 3, and 6, and early growth response factor 1). In contrast, most up-regulated genes (e.g., caspase-3, p21, tissue inhibitor of metalloproteinases 1, 2, and 3, and adenomatosis polyposis coli) are known for their antiangiogenic functions which include the promotion of cell apoptosis and cell cycle arrest and the inhibition of tumor growth and metastasis. These results show that the antiangiogenic activity of antithrombin is mediated at least in part by a global genetic reprogramming of endothelial cells and strongly implicate an endothelial cell ligand-receptor signaling mechanism in this reprogramming.

Identification and analysis of tumour-associated antigens in hepatocellular carcinoma

To identify tumour and tumour-associated antigens in patients with hepatocellular carcinoma (HCC) one may find potential diagnostic markers and immunotherapeutic targets. In the current study, 30 distinct antigens reactive with serum IgG from HCC patients were identified by serological analysis of cDNA expression libraries (SEREX). The mRNA expression patterns of 14 of these 30 antigens were altered in cancer as further revealed by cDNA microarray, with upregulation for nine and downregulation for five antigens. One of the upregulated antigens was cancer-testis (CT) antigen (CAGE), which had been previously reported to be expressed exclusively in normal gametogenic tissues and aberrantly expressed in a variety of cancer cells. In our study, CAGE mRNA was expressed in 39.4% of HCC patients, 73.3% of patients with gastric cancer and 30.8% of patients with colorectal cancer. Antibodies against CAGE protein were detected in approximately 5.1% of the sera from HCC patients, 8.3% of that from gastric cancer patients and 7.3% of that from colorectal cancer patients. The relative high incidence of CAGE in cancer cells makes it a potential target for vaccine design. Another antigen of great interest is transgelin 2. The overexpression of transgelin 2 mRNA in a large per cent (69%) of HCC points to its potential as a diagnostic marker for HCC.