Protection of Mucuna pruriens seeds against Echis carinatus venom is exerted through a multiform glycoprotein whose oligosaccharide chains are functional in this role

In a previous paper we demonstrated that extracts of Mucuna pruriens seeds (MPE) protect mice against Echis carinatus venom (EV) by an immunological mechanism. In this paper we demonstrate that the MPE immunogen generating the antibody that cross-reacts with the venom proteins is a multiform glycoprotein (gpMuc) whose immunogenic properties mainly reside in its glycan-chains. The glycoprotein was purified from the protein extract of M. pruriens seeds using Concanavalin A affinity chromatography. Using 2-D gel electrophoresis it separated into seven isoforms having MWs in the range from 20.3 to 28.7 kDa and pIs from 4.8 to 6.5. N-terminal sequencing of these spots revealed close similarity since all of them contained the consensus sequence DDREPV-DT found in soybean Kunitz-type trypsin inhibitor. We suggest that gpMuc contains both N- and O-glycans. Mild alkaline treatment but not PNGase F led to loss of reactivity, indicating that O-glycans are probably involved in the antigenicity of gpMuc.

SPI-CI and SPI-6 cooperate in the protection from effector cell-mediated cytotoxicity

Tumors have several mechanisms to escape from the immune system. One of these involves expression of intracellular anticytotoxic proteins that modulate the execution of cell death. Previously, we have shown that the serine protease inhibitor (serpin) SPI-6, which inactivates the cytotoxic protease granzyme B (GrB), is capable of preventing cytotoxic T lymphocyte (CTL)-mediated apoptosis. Despite its potent antiapoptotic activity, SPI-6 does not prevent membranolysis induced by cytotoxic lymphocytes. We now provide evidence that several colon carcinoma cell lines do resist membranolysis and that this protection is dependent on SPI-6 but also requires expression of a closely related serpin called SPI-CI (serine protease inhibitor involved in cytotoxicity inhibition). Expression of SPI-CI is absent from normal colon but observed in placenta, testis, early during embryogenesis, and in cytotoxic lymphocytes. SPI-CI encodes a chymotrypsin-specific inhibitor and irreversibly interacts with purified granzyme M. Moreover, SPI-CI can protect cells from purified perforin/GrM-induced lysis. Our data therefore indicate that SPI-CI is a novel immune escape molecule that acts in concert with SPI-6 to prevent cytotoxic lymphocyte-mediated killing of tumor cells.

Proteases of the complement system

The complement system is a group of about 35 soluble and cell-surface proteins which interact to recognize, opsonize and clear or kill invading micro-organisms or altered host cells (e.g. apoptotic or necrotic cells). Complement is a major part of the innate immune system. Recognition proteins such as C1q, MBL (mannan-binding lectin) and ficolins bind to targets via charge or sugar arrays. Binding causes activation of a series of serine protease proenzymes, such as C1r, C1s and MASP2 (MBL-associated serine protease 2), which in turn activate the atypical serine proteases factor B and C2, which then activate the major opsonin of the system, C3. Activated C3 binds covalently to targets, and is recognized by receptors on phagocytic cells. Two of the complement proteases, factors D and I, circulate not as proenzymes, but in activated form, and they have no natural inhibitors; their substrates are transient protein complexes (e.g. C3bB and C3bH) which form during complement activation. Factor B and C2 also have no natural inhibitor; they are active only when proteolytically cleaved and bound in an unstable, short-lived complex with C3b or C4b. C1r, C1s and the MASPs, in contrast, are regulated more conventionally by the natural serpin, C1-inhibitor. Complement proteases in general have very narrow specificity, and low substrate turnover with both natural and synthetic substrates. Excessive activation of complement is inflammatory, and causes tissue damage (e.g. in rheumatoid arthritis, or in ischaemia/reperfusion injury). Substances that regulate complement activation are likely to be useful in the regulation of inflammation. Complement activation might potentially be controlled at many different steps. Much attention has been focused on controlling the formation or activity of the protease complexes C3bBb and C4b2a (containing activated factor B and C2 respectively), as these generate the inflammatory peptides C3a and C5a.

Invasion by schistosome cercariae: neglected aspects in Schistosoma japonicum

Skin invasion by schistosome cercariae was recently discussed in Trends in Parasitology. However, only Schistosoma mansoni was considered, possibly because this species predominates in laboratory studies (at least outside China). One may be tempted to extrapolate from the "model" S. mansoni to other schistosomes, but Schistosoma japonicum must not be neglected. This schistosome is distinguishable from others (particularly S. mansoni) by virtue of its remarkable speed and success of migration, as well as by specific biochemical and immunological features. This leads to the hypothesis that S. japonicum is atypical with respect to the enzymes that facilitate skin penetration.

Intramolecular dimerization is required for the chlamydia-secreted protease CPAF to degrade host transcriptional factors

We previously identified a chlamydial protein designated CPAF (chlamydia protease/proteasome-like activity factor) that is secreted into host cell cytosol for degrading host transcription factors required for major histocompatibility complex antigen expression. Here we report that CPAF, synthesized as a 70-kDa proprotein, is processed into two fragments (designated CPAFn and CPAFc) to form intramolecular dimers that are much more stable than the naïve CPAF. Precipitation with antibodies that recognized CPAF dimers removed the proteolytic activity responsible for degrading host transcription factor RFX5 from chlamydia-infected host cell cytosol, while precipitation with antibodies that recognized free CPAF fragments alone did not remove this activity. Separation of CPAFn from CPAFc resulted in a loss of proteolytic activity. Furthermore, neither expressed full-length CPAF that was not processed nor coexpressed CPAFn and CPAFc fragments that failed to form dimers degraded RFX5. These observations demonstrate that intramolecular dimerization is required for CPAF to degrade host transcription factors, a strategy that is utilized by an obligate intracellular bacterial species to evade host defenses.

Lack of type 1 sensitization to laundry detergent enzymes among consumers in the Philippines: results of a 2-year study in atopic subjects

BACKGROUND

Enzymes have been safely used in laundry products for many years. The risk of developing adverse responses to enzymes in laundry detergents among consumers in countries where hand laundry predominates is expected to be low.

OBJECTIVES

To understand how consumers in hand laundry markets used detergent products; to show that use of enzyme-containing detergents did not lead to sensitization in an atopic population with compromised skin; and to show that enzyme detergents did not have an adverse effect on skin condition.

METHODS

Women in the rural Philippines were chosen since they do hand laundry for several hours a day, every day. The skin prick test (SPT) tested for the presence of IgE antibody to common aeroallergens and to enzymes in detergent product. Atopic women used enzyme-containing laundry bars for hand laundry and personal cleansing. They also used enzyme-containing laundry granules for hand laundry. All subjects were evaluated by SPT with enzymes over 2 years. Hand and body skin conditions were also evaluated.

RESULTS

None of the 1,980 subjects screened for eligibility into the 2-year study were SPT positive to enzymes, including 655 women who used enzyme-containing detergent for up to 1 year. None of the subjects in the study developed IgE to the enzymes. Enzymes had no adverse effect on skin condition or on the development of erosions on the hands.

CONCLUSIONS

The 2-year study confirms that enzymes are safe for use in laundry products at or below levels tested in the study even when used by atopic consumers under extremely harsh conditions.

Proteasomal expression, induction of immunoproteasome subunits, and local MHC class I presentation in myofibrillar myopathy and inclusion body myositis

Inclusion body myositis (IBM) and myofibrillar myopathy (MM) are diseases characterized by the abnormal accumulation of proteins in muscle fibers, including desmin, alphaB-crystallin, gelsolin, actin, kinases, and phospho-tau, along with ubiquitin in muscle fibers, suggesting abnormal protein degradation as a possible cause of the surplus myopathy. Since the ubiquitin-proteasome system plays a crucial role in non-lysosomal protein degradation, the present study has examined by immunohistochemistry the expression of components of the catalytic core of 20S proteasomes and its regulators: 19S and PA28alpha/beta, and the expression of immunoproteasome subunits LMP2, LMP7, and MECL1 in 8 patients with MM and 10 patients with IBM. The patients with MM were from 6 unrelated families, 2 sporadic cases, I with autosomal recessive and 5 with autosomal dominant inheritance. One sporadic patient had a de novo R406W mutation in the desmin gene, and 1 patient with autosomal dominant MM had a single amino acid deletion at position 366 in the desmin gene. Increased immunoreactivity to 20S, 19S, and PA28alpha/beta colocalizing abnormal protein deposits, as revealed in consecutive serial sections, was seen in all cases with MM and IBM. In all cases, the subunits of the immunoproteasome LMP2, LMP7, and MECL1 colocalized with proteasomal immunoreactivity and abnormal protein accumulation. Immunohistochemistry revealed focal MHC class I immunoreactivity in the cytoplasmic membrane of muscle fibers in IBM and in association with protein aggregates in IBM, and to a lesser degree, in MM. The present findings provide a link between abnormal protein accumulation and altered proteasomal expression in IBM and MM.

Time-controlled transcardiac perfusion cross-linking for the study of protein interactions in complex tissues

Because of their sensitivity to solubilizing detergents, membrane protein assemblies are difficult to study. We describe a protocol that covalently conserves protein interactions through time-controlled transcardiac perfusion cross-linking (tcTPC) before disruption of tissue integrity. To validate tcTPC for identifying protein-protein interactions, we established that tcTPC allowed stringent immunoaffinity purification of the gamma-secretase complex in high salt concentrations and detergents and was compatible with mass spectrometric identification of cross-linked aph-1, presenilin-1 and nicastrin. We then applied tcTPC to identify more than 20 proteins residing in the vicinity of the cellular prion protein (PrPC), suggesting that PrP is embedded in specialized membrane regions with a subset of molecules that, like PrP, use a glycosylphosphatidylinositol anchor for membrane attachment. Many of these proteins have been implicated in cell adhesion/neuritic outgrowth, and harbor immunoglobulin C2 and fibronectin type III-like motifs.

In vitro and in vivo studies of the Yrp1 protease from Yersinia ruckeri and its role in protective immunity against enteric red mouth disease of salmonids

Yersinia ruckeri, the etiological agent of the enteric red mouth disease (ERM) of salmonids, produces Yrp1, a serralysin metalloprotease involved in pathogenesis. We describe here the hydrolytic and immunogenic properties of Yrp1. The protease was able to hydrolyze different matrix and muscle proteins as laminin, fibrinogen, gelatine, actin, and myosin but not type II and IV collagens. In addition, the Yrp1 protein, when inactivated by heat and used as an immunogen, was able to elicit a strong protection against the development of ERM. The analysis of different Y. ruckeri strains with (Azo+) or without (Azo-) Yrp1 activity showed that all of them contained the yrp1 operon. By using yrp1::lacZ operon fusions, protease production analysis, and complementation studies, it was possible to show that an Azo- strain was blocked at the transcription level. The transcriptional study of the yrp1 operon under different environmental conditions showed that it was regulated by osmolarity and temperature, without pH influence. Finally, when beta-galactosidase activity was used as a probe in vivo, the progression of the disease in the fish could be visualized, and the tropism of the bacterium and affected organs could be defined. This system opens a vast field of study not only with regard to fish disease progression but also in pathogen interactions, temporal gene expression, carrier stages, antibiotic resistance selection, etc.

Persistency of Adenoviral-Mediated Lysostaphin Expression in Goat Mammary Glands

Gene therapy has great potential to enable synthesis of protein molecules in targeted cells of an animal. One application may be the production of antibacterial enzymes by the mammary gland as a means of preventing or treating mastitis. We have previously demonstrated that goat mammary cells are capable of producing lysostaphin, an antistaphylococcal enzyme, after being transduced in vivo with a recombinant adenoviral vector containing a modified lysostaphin gene (Ad-lys). The current study examined duration of expression, and antibody response to lysostaphin and the adenoviral vector. Following intramammary infusion into nonlactating goats (n = 4), recovery of transducible adenoviral vector in mammary secretions persisted for 11 d. Transducible vector was not detected in serum, saliva, urine, or feces. Peak lysostaphin concentrations (< 20 microg/mL) in mammary secretions of infused udders were detected approximately 1 wk postinfusion, and generally returned to undetectable levels after an additional 1 to 2 wk. The poor persistency of expression was likely due to the very potent immune response to both the adenovirus and the expressed lysostaphin. Serum IgG antibodies recognizing the adenoviral vector developed within 7 d of the infusion, and titers rose dramatically to greater than 1:1 x 10(5). Similar titers of serum IgG antibodies to lysostaphin developed in 3 goats, with more moderate titers in the fourth goat. The antibody response to lysostaphin was delayed by approximately 4 d in comparison to the response to the adenovirus. Serum IgG antibody profiles were reflected in mammary secretions. No IgA antibodies to adenovirus or lysostaphin were detected in sera or mammary secretion. We demonstrate that while the lysostaphin gene can be introduced to the mammary gland using an adenoviral-mediated gene transfer technique, the strong immune response that it provokes makes the approach unsuitable for combating mastitis.

German cockroach extract activates protease-activated receptor 2 in human airway epithelial cells

BACKGROUND

The German cockroach has been reported to act as an allergen that might be associated with a protease reaction in asthma. However, the molecular identities of the antigens in German cockroach extract (GCE) with protease activity and the protease-activated receptors (PARs) that are activated by GCE in human airway epithelial cells have not been characterized.

OBJECTIVE

We investigated the direct effect of GCE on Ca(2+) signaling in human airway epithelial cells and the type of PARs activated by GCE.

METHODS

The Ca(2+)-sensitive dye Fura2 was used to determine intracellular Ca(2+) concentration ([Ca(2+)](i)) by means of spectrofluorometry.

RESULTS

GCE induced a baseline type of [Ca(2+)](i) oscillations in a dose-dependent manner. The oscillations persisted for long periods of time in the absence of Ca(2+) entry across the plasma membrane, suggesting that the observed [Ca(2+)](i) increases were due to Ca(2+) release from intracellular stores. Accordingly, after depleting endoplasmic reticulum Ca(2+) with thapsigargin, an endoplasmic reticulum Ca(2+) ATPase inhibitor, the GCE-mediated [Ca(2+)](i) signals were abolished. Whereas desensitization of PAR-1, PAR-3, and PAR-4 had no effect on GCE-mediated Ca(2+) mobilization, no GCE-mediated [Ca(2+)](i) increase was observed after desensitization of PAR-2.

CONCLUSIONS

These results indicate that GCE has a direct effect on human airway epithelial cells, in particular generating [Ca(2+)](i) oscillations through Ca(2+) release from thapsigargin-sensitive Ca(2+) stores through activation of PAR-2.

Monoclonal antibodies against a 62 kDa proteinase of Trichomonas vaginalis decrease parasite cytoadherence to epithelial cells and confer protection in mice

Trichomonas vaginalis infects the epithelium of the genital tract. The mechanism by which it invades the tissue leading to the disease is not thoroughly understood. However, results of several studies seem to agree that parasite adhesion to epithelium cells is the initial step leading to infection in women. T. vaginalis is associated with high levels of proteolytic activity. The role of some of these proteinases in the development of infection has been demonstrated. The current study establishes the role of a 62 kDa excretion-secretion proteinase in parasite cytoadherence. Monoclonal antibodies (MAbs) against this enzyme were tested for their ability to inhibit this process. Three stable hybrid producers of IgG(1)class MAbs (4D8, 1A8, 3C11) against the 62 kDa proteinase were obtained. Two of them (4D8 and 1A8) showed parasite recognition by immunofluorescence. Parasite cytoadherence to a monolayer of HeLa cells was inhibited by the 4D8, 1A8 and 3C11 antibodies. MAb 4D8 administered 24 h before a challenge with T. vaginalis by the intraperitoneal route was able to protect the majority of mice. Nitric oxide levels in the serum of animals inoculated with MAb 4D8 and challenged with the parasite were significantly different from those recorded in mice treated with an unrelated MAb. These studies show that an appropriate antibody against 62 kDa proteinase can help the host resist a challenge by the intraperitoneal route with T. vaginalis.

The insulin-like growth factor system in advanced breast cancer

Despite improvements in therapy, the prognosis for advanced breast cancer is poor and a search for new treatment targets and key regulators of tumour growth is warranted. Extensive data are available on the importance of the insulin-like growth factor (IGF) system in growth regulation of breast cancer cell lines in vitro, indicating that the IGF-I receptor (IGF-IR), IGF-I (and IGF-II) function as survival factors, while IGF binding protein (IGFBP)-3 may act as a growth inhibitor. There is a tight link between the growth regulatory pathways of IGFs and oestrogens in oestrogen-receptor(OR)-positive breast cancer cells. In vivo studies indicate a role of IGF-I and IGF-IR in breast cancer development. However, the importance of the IGF system in metastatic and highly aggressive breast tumours in vivo is not clear, and therapeutic strategies designed to interrupt IGF signalling have not yet proved to be an effective treatment modality in patients with metastatic breast cancer.

Effect of a bacterial pheromone peptide on host chemokine degradation in group A streptococcal necrotising soft-tissue infections

BACKGROUND

Necrotising soft-tissue infections due to group A streptococcus (GAS) are rare (about 0.2 cases per 100000 people). The disease progresses rapidly, causing severe necrosis and hydrolysis of soft tissues. Histopathological analysis of necrotic tissue debrided from two patients (one with necrotising fasciitis and one with myonecrosis) showed large quantities of bacteria but no infiltrating neutrophils. We aimed to investigate whether the poor neutrophil chemotaxis was linked with the ability of group A streptococcus (GAS) to degrade host chemokines.

METHODS

We did RT-PCR, ELISA, and dot-blot assays to establish whether GAS induces synthesis of interleukin 8 mRNA, but subsequently degrades the released chemokine protein. Class-specific protease inhibitors were used to characterise the protease that degraded the chemokine. We used a mouse model of human soft-tissue infections to investigate the pathogenic relevance of GAS chemokine degradation, and to test the therapeutic effect of a GAS pheromone peptide (SilCR) that downregulates activity of chemokine protease.

FINDINGS

The only isolates from the necrotic tissue were two beta-haemolytic GAS strains of an M14 serotype. A trypsin-like protease released by these strains degraded human interleukin 8 and its mouse homologue MIP2. When innoculated subcutaneously in mice, these strains produced a fatal necrotic soft-tissue infection that had reduced neutrophil recruitment to the site of injection. The M14 GAS strains have a missense mutation in the start codon of silCR, which encodes a predicted 17 aminoacid pheromone peptide, SilCR. Growth of the M14 strain in the presence of SilCR abrogated chemokine proteolysis. When SilCR was injected together with the bacteria, abundant neutrophils were recruited to the site of infection, bacteria were cleared without systemic spread, and the mice survived. The therapeutic effect of SilCR was also obtained in mice challenged with M1 and M3 GAS strains, a leading cause of invasive infections.

INTERPRETATION

The unusual reduction in neutrophils in necrotic tissue of people with GAS soft-tissue infections is partly caused by a GAS protease that degrades interleukin 8. In mice, degradation can be controlled by administration of SilCR, which downregulates GAS chemokine protease activity. This downregulation increases neutrophil migration to the site of infection, preventing bacterial spread and development of a fulminant lethal systemic infection.

Proteinase and gelatinolytic properties of a bat feces extract

It was previously demonstrated that a bat feces extract (BAT) was able to produce a specific IgG in animals, a specific IgE in respiratory atopic humans and a hypersensitivity pneumonitis in guinea pigs. As numerous allergens (such as house-dust mite, cockroaches and pollens) revealed a enzymatic activity measured by different assays we decided to study the proteinase and the gelatinolytic activities of the BAT. Several protease inhibitors such as E-64, TLCK, TPCK, PMSF, leupeptin, o-phenantroline and pepstatin-A were applied to establish the chemical properties of the enzymatic activity. These assays revealed a serine-trypsin-like proteolytic and gelatinolytic activities specially at pH 8,5. On the other hand, two bands of 21 and 40 kDa reacted with the human atopic sera suggesting a possible correlation between allergenicity and proteinase activity. Their role in the etiology of perennial rhinitis and asthma requires further investigations.

Cockroach proteases increase IL-8 expression in human bronchial epithelial cells via activation of protease-activated receptor (PAR)-2 and extracellular-signal-regulated kinase

BACKGROUND

We have shown that serine proteases in German cockroach extract increase TNF-alpha-induced expression of IL-8 in human bronchial epithelial cells. The mechanism by which cockroach proteases regulate cytokine expression is unknown; however, protease-activated receptors (PARs) might play a role.

OBJECTIVE

We sought to determine the role of PARs and extracellular-signal-regulated kinase (ERK) in cockroach-induced regulation of IL-8 expression.

METHODS

16HBE14o- human bronchial epithelial cells were treated with the specific PAR-1 and PAR-2 agonists, TFRIFD and SLIGKV, respectively. IL-8 transcription was assessed by transiently transfecting cells with a luciferase-tagged IL-8 promoter construct, and in some cases, dominant-negative expression vectors. To block PAR cleavage, antibodies against the cleavage region of PAR-1 and PAR-2 were used. ERK phosphorylation was determined by Western blot.

RESULTS

Although both PAR-1 and PAR-2 were endogenously expressed in 16HBE14o- cells, selective activation of PAR-2 but not PAR-1 mimicked the effect of cockroach extract on IL-8 expression. Using a blocking antibody against cleavage of PAR-2 but not PAR-1 attenuated cockroach-extract-induced responses, suggesting that cockroach proteases cleave PAR-2. Treatment of cells with cockroach extract and SLIGKV each increased phosphorylation of ERK. Chemical or genetic inhibition of Ras and mitogen-activated protein kinase/ERK (MEK), upstream activators of ERK, each attenuated cockroach- and PAR-2-induced IL-8 transcription.

CONCLUSION

Cockroach proteases and PAR-2 activation synergistically increase TNF-alpha-induced IL-8 transcription via activation of ERK. These data suggest an important role for PAR-2 and ERK activation in the regulation of cytokine expression in airway epithelium in response to cockroach proteases.

The nature and prospects for gut membrane proteins as vaccine candidates for Haemonchus contortus and other ruminant trichostrongyloids

Substantial progress has been made in the last decade in identifying several antigens from Haemonchus contortus which, in their native form, stimulate useful levels of protective immunity (70-95% reductions in faecal egg output) in the ovine host. Much work has focussed on proteins/protein complexes expressed on the surface of the worm gut which are exposed to the blood meal, and, hence, antibody ingested with it. The antigens generally, but not in all cases, show protease activity and antibody is thought to mediate protective immunity by blocking the activity of enzymes involved in digestion within the worm. This review summarises the protective efficacy, as well as the biochemical and molecular properties, of the principal candidate antigens which are expressed in the gut of these parasites. Of course, such antigens will have to be expressed as recombinant proteins to be sufficiently cost-effective for use in a commercial vaccine and the current status of recombinant antigen expression is discussed with particular reference to conformation and glycosylation. There is a need for continued antigen definition even in the confines of gut antigens and potential targets can be selected from the rapidly expanding genome/EST datasets on the basis of predicted functional homology. Gene knockout technologies such as RNA interference have the potential to provide high throughput, rapid and inexpensive methods to define whether the protein product of a particular gene would be a suitable vaccine candidate.

Human population-based identification of CD4(+) T-cell peptide epitope determinants

A human cell-based method to identify functional CD4(+) T-cell epitopes in any protein has been developed. Proteins are tested as synthetic 15-mer peptides offset by three amino acids. Percent responses within a large donor population are tabulated for each peptide in the set. Peptide epitope regions are designated by difference in response frequency from the overall background response rate for the compiled dataset. Epitope peptide responses are reproducible, with a median coefficient of variance of 21% when tested on multiple random-donor sets. The overall average response rate within the dataset increases with increasing putative human population antigenic exposure to a given protein. The background rate was high for HPV16 E6, and was low for human-derived cytokine proteins. The assay identified recall epitope regions within the donor population for the protein staphylokinase. For an industrial protease with minimal presumed population exposure, immunodominant epitope peptides were identified that were found to bind promiscuously to many HLA class II molecules in vitro. The peptide epitope regions identified in presumably unexposed donors represent a subset of the total recall epitopes. Finally, as a negative control, the assay found no peptide epitope regions in human beta2-microglobulin. This method identifies functional CD4(+) T-cell epitopes in any protein without pre-selection for HLA class II, suggests whether a donor population is pre-exposed to a protein of interest, and does not require sensitized donors for in vitro testing.

Two isoforms of otubain 1 regulate T cell anergy via GRAIL

The active ubiquitin E3 ligase GRAIL is crucial in the induction of CD4 T cell anergy. Here we show that GRAIL is associated with and regulated by two isoforms of the ubiquitin-specific protease otubain 1. In lethally irradiated mice reconstituted with bone marrow cells from T cell receptor-transgenic mice retrovirally transduced to express the genes encoding these proteases, otubain 1-expressing cells contained negligible amounts of endogenous GRAIL, proliferated well and produced large amounts of interleukin 2 after antigenic stimulation. In contrast, cells expressing the alternatively spliced isoform, otubain 1 alternative reading frame 1, contained large amounts of endogenous GRAIL and were functionally anergic, and they proliferated poorly and produced undetectable interleukin 2 when stimulated in a similar way. Thus, these two proteins have opposing epistatic functions in controlling the stability of GRAIL expression and the resultant anergy phenotype in T cells.

Modulation of Macrophage Activity by Proteolytic Enzymes. Differential Regulation of IL-6 and Reactive Oxygen Intermediates (ROIs) Synthesis as a Possible Homeostatic Mechanism in the Control of Inflammation

Inflammatory foci are rich in proteases released by neutrophils (serine proteases) and macrophages (metalloproteases). These enzymes can degrade extracellular matrix proteins and cell membrane bound proteins thus contributing to the development and progression of inflammatory reaction. In this study we have investigated the influence of collagenase (metalloprotease) and trypsin (serine protease) on murine resident and oil-induced peritoneal macrophages (Mf). Short in vitro treatment of Mf, not affecting cell viability, significantly reduced the release of reactive oxygen intermediates (ROIs) and at the same time triggered the increase of IL-6 production and to lesser extent of TNF-alpha production. Both these effects were dependent on enzyme concentration used and were particularly well pronounced in resident macrophages. In addition both enzymes cleaved a number of cell-membrane molecules, including CD23, CD14, CD95L, and Mac-3. We hypothesize that the enzymatic digestion of certain Mf surface receptor proteins in inflammatory foci may be responsible for modification of cell behaviour either by preventing the generation of specific signal or alternatively by delivering a mock substitute signal to the cell interior. In effect inhibition of ROIs production limits their destructive effects and the increase in the secretion of IL-6 stimulates the synthesis of acute phase proteins and triggers other anti-inflammatory mechanisms thus directing Mf present in inflammatory foci into regulatory pathway rather than allowing them to perform solely the effector function.

Metalloendopeptidases from the intestinal brush border of Haemonchus contortus as protective antigens for sheep

Substantial protection against the economically important nematode Haemonchus contortus has been achieved by immunizing sheep with a glycoprotein fraction isolated from the intestinal membranes of this parasite. This fraction has been termed Haemonchus galactose-containing glycoprotein complex (H-gal-GP) since it was originally isolated through its selective binding to lectins with a specificity for N-acetylgalactosamine. A major component of this highly protective antigen complex is a family of four zinc metalloendopeptidases, designated MEPs 1-4. Various combinations of these MEPs were evaluated in immunization-challenge trials in sheep. In two experiments a combination of all four MEPs, separated from the rest of the complex by gel filtration in 8 m urea, significantly reduced H. contortus egg counts by 45 and 50%, an effect not significantly different from that conferred by 8 m urea treatment of H-gal-GP itself. Similarly, MEP3 alone or MEPs 1, 2 and 4 in combination, electroeluted from the complex following SDS gel electrophoresis, each reduced egg counts by some 33%. The MEPs are therefore protective components of H-gal-GP and from previously published findings, it appears that MEP3 is the most effective member of this metalloendopeptidase family. However, there was no significant protection when sheep were immunized with fully reduced and denatured H-gal-GP or with bacterially expressed recombinant forms of MEP 1 or the principal domains of MEP3, suggesting that conformational epitopes on the MEPs are required for immunity.

Parasite antigenaemia and IgG4 antibodies to a filarial protease in an endemic human population in India

Levels of circulating filarial antigen (Og4C3) and IgG4 antibodies to a filarial protease were determined in subjects of Wuchereria bancrofti exposed sera from Orissa, India. In addition to all individuals with antigenaemia (microfilaraemia), IgG4 antibodies were also detected in some individuals without antigenaemia. A 2-year longitudinal follow-up indicated that IgG4 seropositivity in asymptomatic amicrofilaraemics could be a risk factor for acquiring infection (antigenaemia).

Degradation of β-Amyloid by Proteolytic Antibody Light Chains

Deposition of beta-amyloid (Abeta) is considered an important early event in the pathogenesis of Alzheimer's disease (AD). Clearance of Abeta thus represents a potential therapeutic approach. Antibody-mediated clearance of Abeta by vaccination inhibited and cleared Abeta deposition in animal models; however, inflammatory side effects were observed in humans. An alternative potentially noninflammatory approach to facilitate clearance is to proteolytically cleave Abeta. We screened 12 proteolytic recombinant antibody fragments for potential alpha-secretase activity, a naturally occurring enzyme that cleaves between the Lys16 and Leu17 residues of the amyloid precursor protein (APP). We utilized the synthetic alpha-secretase substrate, benzyloxycarbonyl-l-lysine o-nitrophenyl ester (Z-lys-o-Np) as a preliminary screen for alpha-secretase activity. Two antibody light chain fragments that hydrolyzed Z-lys-o-Np were identified. Abeta hydrolysis was studied using mass spectrometry to identify the cleavage patterns of the antibodies. The recombinant antibody light chain antibody fragment, c23.5, showed alpha-secretase-like activity, producing the 1-16 and 17-40 amino acid fragments of Abeta. The second light chain antibody fragment, hk14, demonstrated carboxypeptidase-like activity, cleaving sequentially from the carboxyl terminal of Abeta. These antibody light chains provide a novel route toward engineering efficient therapeutic antibodies capable of cleaving Abeta in vivo.

A New Glycoprotein Allergen/Antigen with the Protease Activity from Aspergillus fumigatus

BACKGROUND

Aspergillus fumigatus is an opportunistic fungus causing allergic and invasive aspergillosis in humans and animals. It secretes an array of complex biologically active glycoprotein antigens and allergens. It is important to identify and characterize probable potential virulent factors playing a major role in the pathogenesis of aspergillosis.

METHODS

Using protein purification techniques (lectin affinity chromatography, gel filtration, electroelution and high-pressure liquid chromatography), a major antigen/allergen with a molecular weight of 56 kD (gp56) from A. fumigatus was purified to homogeneity. The protein was characterized by immunoblot, ELISA and protease assays. The N-terminal amino acid sequencing was performed.

RESULTS

The gp56 protein showed a single band on silver staining and isoelectric focussing. The protein to carbohydrate ratio was 1.5:1 and gp56 gave a protein band at a molecular weight of 34 kD on enzymatic deglycosylation. It also exhibited IgG and IgE immunobinding with antibodies present in sera of allergic bronchopulmonary aspergillosis patients. The gp56 exhibited protease activity and N-terminal seven-amino acid sequence showed homology with fungal serine proteases.

CONCLUSIONS

The gp56 protein by virtue of its proteolytic activity could be one of the virulent factors of A. fumigatus involved in establishing infection in the host along with other factors.

Aspartyl proteases from the intestinal brush border of Haemonchus contortus as protective antigens for sheep

A novel pepsin-like aspartyl protease was identified as a component of Haemonchus galactose-containing glycoprotein (H-gal-GP), which is an integral membrane glycoprotein complex located on the intestinal cells of Haemonchus contortus, and a highly protective antigen for sheep. This molecule, designated HcPEP2, showed 50% sequence identity with a previously described aspartyl protease from H-gal-GP known as HcPEP1. Fractions of H-gal-GP, either containing both HcPEP1 and 2 or other lower molecular weight components of the complex, were evaluated as protective antigens in immunization - challenge trials in sheep. When separated from the rest of the complex by gel filtration in 8 m urea, the HcPEP1 and 2 fraction significantly reduced H. contortus egg counts by 48% and worm numbers by 36%, but the lower molecular weight components were not significantly protective. However, the HcPEP1 and 2 fraction did not protect if electro-eluted from SDS-dissociated H-gal-GP, nor did bacterially expressed recombinant HcPEP1, suggesting that conformational epitopes are important for inducing immunity.