Characterization of the Inflammatory Response to Severe COVID-19 Illness

Rationale: Coronavirus disease (COVID-19) is a global threat to health. Its inflammatory characteristics are incompletely understood.Objectives: To define the cytokine profile of COVID-19 and to identify evidence of immunometabolic alterations in those with severe illness.Methods: Levels of IL-1β, IL-6, IL-8, IL-10, and sTNFR1 (soluble tumor necrosis factor receptor 1) were assessed in plasma from healthy volunteers, hospitalized but stable patients with COVID-19 (COVIDstable patients), patients with COVID-19 requiring ICU admission (COVIDICU patients), and patients with severe community-acquired pneumonia requiring ICU support (CAPICU patients). Immunometabolic markers were measured in circulating neutrophils from patients with severe COVID-19. The acute phase response of AAT (alpha-1 antitrypsin) to COVID-19 was also evaluated.Measurements and Main Results: IL-1β, IL-6, IL-8, and sTNFR1 were all increased in patients with COVID-19. COVIDICU patients could be clearly differentiated from COVIDstable patients, and demonstrated higher levels of IL-1β, IL-6, and sTNFR1 but lower IL-10 than CAPICU patients. COVID-19 neutrophils displayed altered immunometabolism, with increased cytosolic PKM2 (pyruvate kinase M2), phosphorylated PKM2, HIF-1α (hypoxia-inducible factor-1α), and lactate. The production and sialylation of AAT increased in COVID-19, but this antiinflammatory response was overwhelmed in severe illness, with the IL-6:AAT ratio markedly higher in patients requiring ICU admission (P < 0.0001). In critically unwell patients with COVID-19, increases in IL-6:AAT predicted prolonged ICU stay and mortality, whereas improvement in IL-6:AAT was associated with clinical resolution (P < 0.0001).Conclusions: The COVID-19 cytokinemia is distinct from that of other types of pneumonia, leading to organ failure and ICU need. Neutrophils undergo immunometabolic reprogramming in severe COVID-19 illness. Cytokine ratios may predict outcomes in this population.

Measurement of the α1-proteinase inhibitor (α1-antitrypsin) of common marmoset and intestinal protein loss in wasting syndrome

Although wasting marmoset syndrome (WMS) is one of the biggest problems facing captive marmoset colonies, the mechanisms underlying its pathogenesis remain unclear. In our clinical experience, it is difficult to cure WMS-affected marmosets with severe hypoalbuminemia. Thus, the mechanisms underlying hypoalbuminemia in WMS must be understood. In the present study, we investigated whether intestinal protein loss, a known reason for hypoalbuminemia, occurs in this disease. Fecal α1-proteinase inhibitor (α1-PI, also known as α1-antitrypsin) has been used to diagnose intestinal protein loss in other species. To develop an assay system for this protein, marmoset α1-PI was purified from plasma and antibodies against it were developed using the purified protein. Using the antibodies, a sandwich enzyme-linked immunosorbent assay (ELISA) to measure marmoset α1-PI was developed, and its detection sensitivity for fecal samples was ∼20-fold higher than that of a commercial kit for human α1-PI. From this ELISA, the reference intervals for serum and feces of healthy marmosets were 0.87-1.85 mg/ml and 0.53-395.58 μg/g, respectively. The average concentrations of α1-PI in serum and feces of seven WMS-affected marmosets were 1.17 mg/ml and 1357.58 μg/g, respectively. Although there were no significant differences in the serum concentrations between healthy and WMS-affected marmosets, the fecal concentrations were significantly higher in WMS-affected marmosets than in healthy individuals, suggesting that intestinal protein loss occurs in WMS. Intestinal protein loss of WMS-affected marmosets was significantly attenuated with treatment, suggesting that it is one of the mechanisms involved in the hypoalbuminemia observed in WMS.

Vitamin D (1,25(OH)2D3) induces α-1-antitrypsin synthesis by CD4+ T cells, which is required for 1,25(OH)2D3-driven IL-10

Studies to identify novel immune-regulatory functions of active vitamin D (1,25(OH)2D3) in human CD4+ T cells revealed that 1,25(OH)2D3 potently induced expression of the gene SERPINA1, encoding the anti-protease α-1-antitrypsin. We confirmed α-1-antitrypsin protein expression by 1,25(OH)2D3-treated CD4+ T cells, but not in CD8+ T cells or monocytes. α-1-Antitrypsin promotes anti-inflammatory IL-10 synthesis in other immune cell populations. We therefore investigated its immune-regulatory effects in CD4+ T cells. Plasma-derived α-1-antitrypsin drove IL-10 synthesis by CD4+ T cells, which was not dependent on anti-protease activity, but appeared to require a serum-binding factor, since this could not be achieved with recombinant protein. α-1-Antitrypsin is reported to bind complement components, which regulate T cell function. A role for this interaction was therefore probed. Plasma-derived, but not recombinant α-1-antitrypsin contained C3a. Surface Plasmon Resonance and Microscale Thermophoresis demonstrated α-1-antitrypsin binding to C3a. Addition of C3a to CD4+ T cells cultured with recombinant α-1-antitrypsin restored induction of IL-10, whereas neutralisation of C3a abrogated IL-10 induced by plasma-derived α-1-antitrypsin. To interrogate an endogenous role for the α-1-antitrypsin-C3a axis in 1,25(OH)2D3-driven CD4+ T cell IL-10 synthesis, we treated cells from healthy or α-1-antitrypsin-deficient individuals (which transcribe SERPINA1 but do not secrete protein) with 1,25(OH)2D3. A significant correlation was identified between SERPINA1 and IL10 gene expression in healthy donor CD4+ T cells, which was absent in cells from α-1-antitrypsin-deficient individuals. Therefore, α-1-antitrypsin is required for 1,25(OH)2D3-induced IL-10 expression in CD4+ T cells, interacting with C3a to drive IL-10 expression.

Study of kallikrein-related peptidase 6 (KLK6) and its complex with α1-antitrypsin in biological fluids

BACKGROUND

Human kallikrein-related peptidase 6 (KLK6) is a member of the kallikrein family of serine proteases. KLK6 is synthesized as a preproenzyme, mainly in tissues of the central nervous system (CNS), and secreted as an inactive precursor. Serum KLK6 is a biomarker of unfavorable prognosis for ovarian cancer, but its sensitivity for early detection is relatively low. Differential glycosylation of KLK6 has been identified in ascites fluid obtained from ovarian cancer patients, suggesting the presence of unique KLK6 isoforms in biological samples.

METHODS

In the present study, we applied a two-step enrichment approach for KLK6 in ovarian cancer ascites, followed by mice immunization and production of monoclonal antibodies. Immunoaffinity techniques coupled to mass spectrometric methods were employed for hybridoma screening and target antigen identification.

RESULTS

We found that the main target of the newly-generated monoclonal antibodies target was the serine protease inhibitor α1-antitrypsin (A1AT). Additional experiments confirmed that A1AT is the main inhibitor of KLK6 in biological fluids. One new antibody (24ED138) was chosen to build a hybrid assay for the accurate quantification of the A1AT-KLK6 complex in biological samples. The aforementioned assay was evaluated with serum samples collected from patients with ovarian cancer (n=24) and normal donors (n=16) and showed slight improvement in sensitivity (~12%) compared to the standard in-house KLK6 assay.

CONCLUSIONS

We conclude that KLK6 is present in biological fluids either as free form, or bound to A1AT, and the bound form performs better than total KLK6 as a biomarker of ovarian carcinoma.

Low-density lipoprotein receptor-related protein 1 mediates α1-antitrypsin internalization in CD4+ T lymphocytes

In α1-antitrypsin-deficient HIV patients, an accelerated decline of CD4(+) T cell numbers is observed, suggesting that α1-antitrypsin is a potential endogenous HIV inhibitor. In infected T lymphocytes, α1-antitrypsin potently blocks NF-κB activation and HIV-1 replication by directly interacting with IκBα in the cytosol, thereby altering its ubiquitination pattern. However, the mechanism of α1-antitrypsin entry into the cytosol, where IκBα locates, remains unclear. In the present study, we investigated the mechanism of α1-antitrypsin internalization in CD4(+) T cells. Thus, primary CD4(+) T cells were infected with HIV-1 and then incubated with α1-antitrypsin to detect its internalization. We found that CD4(+) T cells internalized α1-antitrypsin through a clathrin-dependent endocytosis process. Next, intracellular α1-antitrypsin exerted the inhibitory effect on NF-κB activation and HIV-1 replication. On primary CD4(+) T cells, α1-antitrypsin interacted with low-density lipoprotein receptor-related protein 1 to initiate the internalization. Inside CD4(+) T lymphocytes, α1-antitrypsin was transported from the endosome to the lysosome and then released into the cytosol, where it is possible for α1-antitrypsin to directly interact with IκBα. These results together suggest that α1-antitrypsin internalization is a clathrin-dependent and low-density lipoprotein receptor-related protein 1-mediated endocytosis process. Internalized α1-antitrypsin is transported through the endosome-lysosome-cytosol routine to interact with cytosolic IκBα and block NF-κB activation and HIV-1 replication.

Immune-modulating effects of alpha-1 antitrypsin

Alpha-1 antitrypsin (AAT) is a circulating serine protease inhibitor (serpin) that inhibits neutrophil elastase in the lung, and AAT deficiency is associated with early-onset emphysema. AAT is also a liver-derived acute-phase protein that, in vitro and in vivo, reduces production of pro-inflammatory cytokines, inhibits apoptosis, blocks leukocyte degranulation and migration, and modulates local and systemic inflammatory responses. In monocytes, AAT has been shown to increase intracellular cAMP, regulate expression of CD14, and suppress NFκB nuclear translocation. These effects may be mediated by AAT's serpin activity or by other protein-binding activities. In preclinical models of autoimmunity and transplantation, AAT therapy prevents or reverses autoimmune disease and graft loss, and these effects are accompanied by tolerogenic changes in cytokine and transcriptional profiles and T cell subsets. This review highlights advances in our understanding of the immune-modulating effects of AAT and their potential therapeutic utility.

α1-Antitrypsin Combines with Plasma Fatty Acids and Induces Angiopoietin-like Protein 4 Expression

α1-Antitrypsin (A1AT) purified from human plasma upregulates expression and release of angiopoietin-like protein 4 (Angptl4) in adherent human blood monocytes and in human lung microvascular endothelial cells, providing a mechanism for the broad immune-regulatory properties of A1AT independent of its antiprotease activity. In this study, we demonstrate that A1AT (Prolastin), a potent inducer of Angptl4, contains significant quantities of the fatty acids (FA) linoleic acid (C18:2) and oleic acid (C18:1). However, only trace amounts of FAs were present in preparations that failed to increase Angplt4 expression, for example, A1AT (Zemaira) or M-type A1AT purified by affinity chromatography. FA pull-down assays with Western blot analysis revealed a FA-binding ability of A1AT. In human blood-adherent monocytes, A1AT-FA conjugates upregulated expression of Angptl4 (54.9-fold, p < 0.001), FA-binding protein 4 (FABP4) (11.4-fold, p < 0.001), and, to a lesser degree, FA translocase (CD36) (3.1-fold, p < 0.001) relative to A1AT devoid of FA (A1AT-0). These latter effects of A1AT-FA were blocked by inhibitors of peroxisome proliferator-activated receptor (PPAR) β/δ (ST247) and PPARγ (GW9662). When compared with controls, cell pretreatment with ST247 diminished the effect of A1AT-LA on Angptl4 mRNA (11.6- versus 4.1-fold, p < 0.001) and FABP4 mRNA (5.4- versus 2.8-fold, p < 0.001). Similarly, preincubation of cells with GW9662 inhibited inducing effect of A1AT-LA on Angptl4 mRNA (by 2-fold, p < 0.001) and FABP4 mRNA (by 3-fold, p < 0.001). Thus, A1AT binds to FA, and it is this form of A1AT that induces Angptl4 and FABP4 expression via a PPAR-dependent pathway. These findings provide a mechanism for the unexplored area of A1AT biology independent of its antiprotease properties.

The immunoregulation effect of alpha 1-antitrypsin prolong β-cell survival after transplantation

Islet transplantation has considerable potential as a cure for diabetes. However, the difficulties that arise from inflammation and the immunological rejection of transplants must be addressed for islet transplantation to be successful. Alpha 1-antitrypsin (AAT) inhibits the damage on β cells caused by inflammatory reactions and promotes β-cell survival and proliferation. This protein also induces specific immune tolerance to transplanted β cells. However, whether the expression of AAT in β cells themselves could eliminate or decrease immunological rejection of transplants is not clear. Therefore, we established a β cell line (NIT-hAAT) that stably expresses human AAT. Interestingly, in a cytotoxic T lymphocyte (CTL)-killing assay, we found that hAAT reduced apoptosis and inflammatory cytokine production in NIT-1 cells and regulated the Th1/Th2 cytokine balance in vitro. In vivo transplantation of NIT-hAAT cells into mice with diabetes showed hAAT inhibited immunological rejection for a short period of time and increased the survival of transplanted β cells. This study demonstrated that hAAT generated remarkable immunoprotective and immunoregulation effects in a model of β cell islet transplantation for diabetes model.

ATZ11 recognizes not only Z-α1-antitrypsin-polymers and complexed forms of non-Z-α1-antitrypsin but also the von Willebrand factor

AIMS

The ATZ11 antibody has been well established for the identification of α1-anti-trypsin (AAT) molecule type PiZ (Z-AAT) in blood samples and liver tissue. In this study, we systematically analyzed the antibody for additional binding sites in human tissue.

METHODS AND RESULTS

Ultrastructural ATZ11 binding was investigated immunoelectron microscopically in human umbilical vein endothelial cells (HUVECs) and in platelets of a healthy individual. Human embryonic kidney (HEK293) cells were transiently transfected with Von Willebrand factor (VWF) and analyzed immunocytochemically using confocal microscopy and SDS-PAGE electrophoresis followed by western blotting (WB). Platelets and serum samples of VWF-competent and VWF-deficient patients were investigated using native PAGE and SDS-PAGE electrophoresis followed by WB. The specificity of the ATZ11 reaction was tested immunohistochemically by extensive antibody-mediated blocking of AAT- and VWF-antigens. ATZ11-positive epitopes could be detected in Weibel-Palade bodies (WPBs) of HUVECs and α-granules of platelets. ATZ11 stains pseudo-WBP containing recombinant wild-type VWF (rVWF-WT) in HEK293 cells. In SDS-PAGE electrophoresis followed by WB, anti-VWF and ATZ11 both identified rVWF-WT. However, neither rVWF-WT-multimers, human VWF-multimers, nor serum proteins of VWF-deficient patients were detected using ATZ11 by WB, whereas anti-VWF antibody (anti-VWF) detected rVWF-WT-multimers as well as human VWF-multimers. In human tissue specimens, AAT-antigen blockade using anti-AAT antibody abolished ATZ11 staining of Z-AAT in a heterozygous AAT-deficient patient, whereas VWF-antigen blockade using anti-VWF abolished ATZ11 staining of endothelial cells and megakaryocytes.

CONCLUSIONS

ATZ11 reacts with cellular bound and denatured rVWF-WT and human VWF as shown using immunocytochemistry and subsequent confocal imaging, immunoelectron microscopy, SDS-PAGE and WB, and immunohistology. These immunoreactions are independent of the binding of Z-AAT-molecules and non-Z-AAT complexes.

[Immunological monitoring of endogenous attack-like psychoses]

To analyze the possibility of using immunological parameters for the assessment of the activity of the process and prediction of the quality and completion of remission, we compared the dynamics of clinical and immunological parameters in 76 patients with endogenous attack-like psychoses during pharmacotherapy of a psychotic episode. Authors confirmed evidence for the activation of innate and adaptive immunity in the acute stage of psychosis as well as the correlation between immunological parameters (leukocyte elastase (LE) activity, alpha(1)-proteinase inhibitor (alpha(1)-PI), the level of autoantibodies to nerve growth factor (Aab-NGF)) and clinical symptoms assessed with the PANSS. The improvement of the clinical state assessed by the reduction in PANSS total score was noted in all patients though there were variations in the dynamics of immunological parameters. The increase of immunological parameters, along with the absence of changes at the discharge from the hospital, suggests that the remission was of low quality and the pathological process did not attenuate. Outpatient examination revealed the different dynamics of psychopathological disorders: stable state in 50% patients, moderate worsening of psychological state in 50% patients. Worsening of clinical symptoms after the discharge and in the outpatient stage was correlated with the elevation of the activity/level of immunological parameters. The changes in LE activity and Aab-NGF level precede the changes in mental state of patients in the following 1-2 months. These parameters may be used for monitoring of patients and prediction of quality and completion of remission.

Human Treg responses allow sustained recombinant adeno-associated virus-mediated transgene expression

Recombinant adeno-associated virus (rAAV) vectors have shown promise for the treatment of several diseases; however, immune-mediated elimination of transduced cells has been suggested to limit and account for a loss of efficacy. To determine whether rAAV vector expression can persist long term, we administered rAAV vectors expressing normal, M-type α-1 antitrypsin (M-AAT) to AAT-deficient subjects at various doses by multiple i.m. injections. M-specific AAT expression was observed in all subjects in a dose-dependent manner and was sustained for more than 1 year in the absence of immune suppression. Muscle biopsies at 1 year had sustained AAT expression and a reduction of inflammatory cells compared with 3 month biopsies. Deep sequencing of the TCR Vβ region from muscle biopsies demonstrated a limited number of T cell clones that emerged at 3 months after vector administration and persisted for 1 year. In situ immunophenotyping revealed a substantial Treg population in muscle biopsy samples containing AAT-expressing myofibers. Approximately 10% of all T cells in muscle were natural Tregs, which were activated in response to AAV capsid. These results suggest that i.m. delivery of rAAV type 1-AAT (rAAV1-AAT) induces a T regulatory response that allows ongoing transgene expression and indicates that immunomodulatory treatments may not be necessary for rAAV-mediated gene therapy.

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.

α1Proteinase inhibitor regulates CD4+ lymphocyte levels and is rate limiting in HIV-1 disease

BACKGROUND

The regulation of adult stem cell migration through human hematopoietic tissue involves the chemokine CXCL12 (SDF-1) and its receptor CXCR4 (CD184). In addition, human leukocyte elastase (HLE) plays a key role. When HLE is located on the cell surface (HLE(CS)), it acts not as a proteinase, but as a receptor for α(1)proteinase inhibitor (α(1)PI, α(1)antitrypsin, SerpinA1). Binding of α(1)PI to HLE(CS) forms a motogenic complex. We previously demonstrated that α(1)PI deficiency attends HIV-1 disease and that α(1)PI augmentation produces increased numbers of immunocompetent circulating CD4(+) lymphocytes. Herein we investigated the mechanism underlying the α(1)PI deficiency that attends HIV-1 infection.

METHODS AND FINDINGS

Active α(1)PI in HIV-1 subjects (median 17 µM, n = 35) was significantly below normal (median 36 µM, p<0.001, n = 30). In HIV-1 uninfected subjects, CD4(+) lymphocytes were correlated with the combined factors α(1)PI, HLE(CS) (+) lymphocytes, and CXCR4(+) lymphocytes (r(2) = 0.91, p<0.001, n = 30), but not CXCL12. In contrast, in HIV-1 subjects with >220 CD4 cells/µl, CD4(+) lymphocytes were correlated solely with active α(1)PI (r(2) = 0.93, p<0.0001, n = 26). The monoclonal anti-HIV-1 gp120 antibody 3F5 present in HIV-1 patient blood is shown to bind and inactivate human α(1)PI. Chimpanzee α(1)PI differs from human α(1)PI by a single amino acid within the 3F5-binding epitope. Unlike human α(1)PI, chimpanzee α(1)PI did not bind 3F5 or become depleted following HIV-1 challenge, consistent with the normal CD4(+) lymphocyte levels and benign syndrome of HIV-1 infected chimpanzees. The presence of IgG-α(1)PI immune complexes correlated with decreased CD4(+) lymphocytes in HIV-1 subjects.

CONCLUSIONS

This report identifies an autoimmune component of HIV-1 disease that can be overcome therapeutically. Importantly, results identify an achievable vaccine modification with the novel objective to protect against AIDS as opposed to the current objective to protect against HIV-1 infection.

Identification of α1-antitrypsin as a positive acute phase protein in ayu (Plecoglossus altivelis) associated with Listonella anguillarum infection

α1-Antitrypsin (AAT) is implicated in the regulation of a variety of mammalian immune responses and was recently identified as a major serpin in blood plasma of some fish. However, AAT expression following bacterial infection in fish has not been well described. In this study, we cloned the full-length ayu (Plecoglossus altivelis) AAT gene cDNA. It contained a 1368-bp coding region, which encodes a 19-amino acids (aa) signal peptide and a 437-aa mature AAT containing the serpin's signature sequence ((427)LKFDRPFMMLV(437)). PNGase F digestion confirmed that the higher molecular mass of the serum AAT was caused by N-glycosylation. Phylogenetic analysis indicated that ayu AAT was closest to that of green spotted pufferfish. AAT transcripts were present in a variety of tissues, with the highest level in the liver. The real-time quantitative PCR data showed that AAT transcripts dramatically increased in various ayu tissues after Listonella anguillarum infection. Western blot analysis revealed that the serum AAT protein level significantly increased in response to inflammation, but displayed no significant changes after cadmium exposure or salinity challenge. This work represents the first report that identifies AAT as a positive acute-phase protein in ayu fish associated with bacterial infection, suggesting that it might play a role in fish innate immunity.

[The role of innate immunity system in the course of adenomyosis]

The investigation of leukocytic elastase (LE) and alpha1-proteinase inhibitor (alpha1-PI) from patients with different stage adenomyosis and in control group was found activation innate immunity system in all the patients with adenomyosis. The degree of LE activity is a prevalence rate of adenomyosis. The degree of alpha1-PI activity is correlated with antiproteolytic potential that blocks the effects shown by LE. It can lead the prognose of disease and timely treatment.

Sustained expression of circulating human alpha-1 antitrypsin reduces inflammation, increases CD4+FoxP3+ Treg cell population and prevents signs of experimental autoimmune encephalomyelitis in mice

Alpha-1-antitrypsin (AAT) is the primary circulating serine protease inhibitor, and is known to exert potent anti-inflammatory effects and to inhibit the progression of several autoimmune diseases. In this study, transgenic mice that over-express surfactant-driven human (h)AAT on the C57BL/6 background were evaluated for resistance to MOG-35-55 peptide-induced experimental autoimmune encephalomyelitis (EAE), compared to WT C57BL/6 control mice. According to the results, sustained levels of circulating hAAT profoundly inhibited induction of clinical signs, inflammatory lesions and demyelination observed in WT mice with EAE, concomitant with enhanced levels of CD4+FoxP3+ Treg cells, reduced secretion of MOG peptide-induced pro-inflammatory cytokines, IL-17, IL-1β & IL-6, diminished expression of caspase-1 and enhanced expression of CCR6. These results implicate hAAT as a potent immunoregulatory agent worthy of further investigation as a potential therapy in human autoimmune diseases including multiple sclerosis.

Serpin-1 splicing isoform J inhibits the proSpätzle-activating proteinase HP8 to regulate expression of antimicrobial hemolymph proteins in Manduca sexta

The innate immune system of insects include the Toll pathway, which is mediated by an extracellular serine proteinase cascade. In the tobacco hornworm, Manduca sexta, hemolymph proteinase 8 (HP8) promotes the synthesis of antimicrobial proteins by cleaving proSpätzle, the putative ligand of M. sexta Toll. HP8 has been observed to form a complex in hemolymph with M. sexta serpin-1, which has multiple alternative splicing isoforms. To investigate the regulation of HP8 and its processing of proSpätzle, we characterized the interaction of recombinant HP8 with serpin-1 isoform J (serpin-1J). Recombinant serpin-1J formed an SDS-stable complex with HP8 in vitro. The association rate constant of serpin-1J and HP8 was 1.3×10(4)M(-1)s(-1), with a stoichiometry of inhibition of 5.4. Serpin-1J inhibited the cleavage of proSpätzle by HP8. Injection of serpin-1J into M. sexta larvae resulted in decreased bacteria-induced antimicrobial activity in hemolymph and reduced expression of cecropin, attacin and hemolin mRNA in fat body. Altogether, these results suggest that serpin-1J functions to inhibit HP8 and thereby modulates the concentration of active Spätzle to regulate the Toll pathway response in M. sexta.

Hepatic regulatory T cells and Kupffer cells are crucial mediators of systemic T cell tolerance to antigens targeting murine liver

The mechanisms of tolerance in the liver that limit susceptibility to food allergy and that mediate the acceptance of liver transplants, even with a complete major histocompatibility complex (MHC) mismatch, remain poorly defined. Here we report that in a model of liver-directed gene transfer, cytotoxic T lymphocyte (CTL) responses to non-self antigens are controlled by hepatic regulatory T cells (Tregs) that secrete the immunosuppressive cytokine interleukin (IL)-10 in response to the antigen. In addition, Kupffer cells (KCs), normally thought to initiate immune responses, are rendered tolerogenic in this context. The depletion of KCs results in a complete abrogation of IL-10 production by hepatic Tregs, indicating an interaction between Tregs and KCs in the induction of tolerance.

CONCLUSION

Our study suggests that hepatic Tregs together with KCs create a local suppressive microenvironment that prevents the establishment of the CTL response. These mechanisms provide pivotal insights and may prove instrumental in the tolerization toward non-self therapeutic proteins delivered to the liver.

Detection of an isoform of α1 -antitrypsin in serum samples from foals with gastric ulcers

The objective of this study was to find serum indicators of gastric ulcers in foals. By using two-dimensional electrophoresis of serum proteins, three distinct spots were detected in samples from foals with gastric ulcers detected endoscopically. One of them appeared with high frequency and was identified by partial digestion with trypsin and subsequent nano-electrospray ionisation-tandem mass spectrometry (nanoesi-ms/ms) analysis as an alpha(1)-antitrypsin. Western blot analysis, using an antibody against human alpha(1)-antitrypsin, revealed at least two bands, of molecular weight 58 kDa and 55 kDa, in the sera. The 55 kDa band was detected in 44 of 47 serum samples from foals with gastric ulcers, but in only three of 22 serum samples from healthy foals.

Isolation and characterization of alpha1-proteinase inhibitor from common carp (Cyprinus carpio) seminal plasma

Using a three-step procedure, we purified (79 and 51.6-fold to homogeneity) and characterized the two isoforms (a and b) of alpha1-proteinase inhibitor-like protein from carp seminal plasma. The isoforms have molecular masses of 55.5 and 54.0 kDa, respectively. These inhibitors formed SDS-stable complexes with cod and bovine trypsin, chymotrypsin and elastase. The thirty-three amino acids within the reactive loop SLPDTVILNRPFLVLIVEDTTKSILFMGKITNP were identified for isoform b. The same first ten amino acids were obtained for isoform a, and this sequence revealed 100% homology to carp alpha1-proteinase inhibitor (alpha1-PI) from perimeningeal fluid. Both isoforms of alpha1-PI are glycoproteins and their carbohydrate content was determined to be 12.6 and 12.1% for a and b, respectively. Our results indicated that alpha1-PI is one of the main proteins of carp seminal plasma. Using polyclonal anti-alpha1-PI antibodies, alpha1-PI was for the first time localized to the carp testis. The presence of alpha1-PI in testis lobules and in the area surrounding spermatides suggests that this inhibitor may be involved in the maintenance of testis connective tissue integrity, control of spermatogenesis or protection of tissue and spermatozoa against unwanted proteolysis. Since similar alpha1-PI has been identified in rainbow trout semen it can be suggested that the presence of alpha1-PI in seminal plasma is a common feature of cyprinid and salmonid fish.

The use of rabbit polyclonal antibodies to assess neoantigenicity following viral reduction of an alpha-1-proteinase inhibitor preparation

The objective of this study was to determine whether the viral reduction processes of nanofiltration and solvent/detergent treatment used in the manufacture of alpha-1 proteinase inhibitor (API) cause neoantigenic changes. Polyclonal antibodies were raised in rabbits against the treated API and quantitatively absorbed with an affinity column containing API that had not undergone viral reduction treatment. Antibodies before and after absorption were measured in a validated ELISA using the immunogen for antibody capture. Antibodies against novel API epitopes were not found after antiserum from rabbits inoculated with treated API was absorbed with untreated API. A positive control, consisting of serum obtained from rabbits inoculated with trinitrophenylated API, showed substantial amounts of measurable antibody following absorption with untreated API. The results suggest that the viral reduction process used does not result in the creation of API neoantigens.

Therapeutic level of functional human alpha 1 antitrypsin (hAAT) secreted from murine muscle transduced by adeno-associated virus (rAAV1) vector

Alpha 1 antitrypsin (AAT) is a serine proteinase inhibitor (serpin). One well-known function of this protein is to inactivate neutrophil elastase and other neutrophil-derived proteinases, and prevent the destruction of pulmonary extracellular matrix. Deficiency of AAT can cause emphysema due to degradation of interstitial elastin by elastase. The majority of circulating AAT is secreted from the liver. Muscle-directed gene therapy using recombinant adeno-associated virus 2 (rAAV2) vectors has been tested to increase the serum levels of AAT. However, inefficient transduction of rAAV2 vector makes it difficult to reach therapeutic levels of AAT in clinical trials and it remains unclear as to whether muscle-secreted AAT is functional. In the present study, we evaluated five serotypes (1, 2, 3, 4, and 5) of rAAV vectors for transduction efficiency in mouse muscle. Results from these studies showed that rAAV1 is the most efficient vector among these serotypes and mediated at least 100-fold higher levels of AAT secretion than the rAAV2 vector. Western blot analysis showed that this murine muscle-secreted human AAT (hAAT) formed a complex with human neutrophil elastase in a dose-dependent manner. An anti-elastase activity assay showed that murine muscle-secreted hAAT inhibited elastase with equal capacity as hAAT purified from plasma. These results provide strong support for the functionality of AAT in ongoing clinical studies of muscle-directed AAT gene therapy.

Analysis of Epitopes on the Unrelated Proteins Thyrotropin Receptor and alpha1-Antitrypsin which are Recognized by A10 Monoclonal Antibody

In a previous study, we noticed an unexpected reaction of an antithyrotropin receptor ectodomain (ETSHR)-reactive monoclonal antibody, A10, with alpha1-antitrypsin (antitrypsin). Presently, we decided to probe the structural basis of this cross-reactivity. Recombinant ETSHR, antitrypsin, synthetic peptides corresponding to the region of similarity in these proteins (EEDFRV and EEDFHV, respectively) and a set of peptides related to this region, N- and C-terminally elongated, were used in the study. Comparing the values of the dissociation constants, we found that the affinity of peptides corresponding to the region of similarity to monoclonal antibody A10 was the same in spite of a difference in one residue (R 38 in ETSHR and H 209 in antitrypsin), whereas a change of E 206 to R in antitrypsin-related peptide dramatically decreased the affinity. The whole binding site of A10 in ETSHR as well as in antitrypsin was larger than the region of similarity. We propose that residues ECHQEEDFV represent the monoclonal antibody A10 epitope. They form an almost continuous sequence of residues 30-37 and 39 in ETSHR. The monoclonal antibody A10 binding site on antitrypsin is shorter. It comprises amino acids 205-208 and 210, from the region of similarity with, probably, additional two residues, H-287 and E 363.