Human recombinant histamine-releasing factor activates human eosinophils and the eosinophilic cell line, AML14-3D10

Therapeutic efficacy of JEW-M449, an anti-TCTP monoclonal antibody, administered via the nasal route in a BALB/c mouse model of ovalbumin-induced acute asthma

Numerous studies have highlighted the role of translationally controlled tumor protein (TCTP) as a key inflammatory mediator of asthma and allergies. Our previous study revealed that blocking the cytokine-like activity of TCTP using JEW-M449, an anti-TCTP monoclonal antibody (mAb), alleviated allergic inflammation in asthmatic mice. This study aimed to determine whether directly delivering JEW-M449 into the respiratory tract is a more effective way of mitigating airway inflammation in a mouse model of ovalbumin (OVA)-induced allergic airway inflammation than delivering this antibody via the intraperitoneal (IP) route. OVA-sensitized mice were intranasally administered JEW-M449 to enable its direct delivery to the respiratory tract before OVA challenge. We evaluated the changes in the levels of bronchoalveolar lavage fluid (BALF) cells, T helper type 2 (Th2) cytokines, OVA-specific immunoglobulin E (IgE), and histopathological alterations in the lung tissues. Intranasal (IN) administration of JEW-M449 significantly ameliorated the pathological changes associated with OVA-induced lung injury, including reduced inflammatory cell infiltration and mucus hypersecretion. Mice IN administered JEW-M449 also showed decreased OVA-mediated induction of Th2 cytokines in BALF and lung homogenates. Importantly, JEW-M449 delivered via the IN route reached the lung tissue more effectively and exerted superior anti-inflammatory effects in OVA-challenged mice than the IP-delivered JEW-M449. This study is the first to demonstrate the efficacy of directly delivering JEW-M449 anti-TCTP mAb into the respiratory tract to alleviate the asthma phenotype in a mouse model, thereby highlighting a potential delivery strategy for novel inhaled mAb therapeutics for human asthma.

Inhibitors of dimerized translationally controlled tumor protein, a histamine releasing factor, may serve as anti-allergic drug candidates

It has been established that translationally controlled tumor protein (TCTP), also called histamine releasing factor (HRF), exhibits cytokine-like activities associated with initiation of allergic responses only after forming dimers (dTCTP). Agents that inhibit dTCTP by preventing its dimerization or otherwise block its function, also block development of allergic reactions, thereby serving as potential drugs to treat allergic diseases. Several lines of evidence have proven that peptides and antibodies that specifically inhibit the interactions between dTCTP and either its putative receptor or immunoglobulins exhibit significant in vivo efficacy as potential anti-inflammatory agents in murine models of allergic inflammatory diseases. This review highlights the development of several inhibitors targeting dTCTP and discusses how they affect the pathophysiologic processes of allergic and inflammatory diseases in several animal models and offers new perspectives on anti-allergic drug discovery.

Transcriptomic Analysis of the Venom Gland and Enzymatic Characterization of the Venom of Phoneutria depilata (Ctenidae) from Colombia

The transcriptome of the venom glands of the Phoneutria depilata spider was analyzed using RNA-seq with an Illumina protocol, which yielded 86,424 assembled transcripts. A total of 682 transcripts were identified as potentially coding for venom components. Most of the transcripts found were neurotoxins (156) that commonly act on sodium and calcium channels. Nevertheless, transcripts coding for some enzymes (239), growth factors (48), clotting factors (6), and a diuretic hormone (1) were found, which have not been described in this spider genus. Furthermore, an enzymatic characterization of the venom of P. depilata was performed, and the proteomic analysis showed a correlation between active protein bands and protein sequences found in the transcriptome. The transcriptomic analysis of P. depilata venom glands show a deeper description of its protein components, allowing the identification of novel molecules that could lead to the treatment of human diseases, or could be models for developing bioinsecticides.

TCTP from Loxosceles Intermedia (Brown Spider) Venom Contributes to the Allergic and Inflammatory Response of Cutaneous Loxoscelism

LiTCTP is a toxin from the Translationally Controlled Tumor Protein (TCTP) family identified in Loxosceles brown spider venoms. These proteins are known as histamine-releasing factors (HRF). TCTPs participate in allergic and anaphylactic reactions, which suggest their potential role as therapeutic targets. The histaminergic effect of TCTP is related to its pro-inflammatory functions. An initial characterization of LiTCTP in animal models showed that this toxin can increase the microvascular permeability of skin vessels and induce paw edema in a dose-dependent manner. We evaluated the role of LiTCTP in vitro and in vivo in the inflammatory and allergic aspects that undergo the biological responses observed in Loxoscelism, the clinical condition after an accident with Loxosceles spiders. Our results showed LiTCTP recombinant toxin (LiRecTCTP) as an essential synergistic factor for the dermonecrotic toxin actions (LiRecDT1, known as the main toxin in the pathophysiology of Loxoscelism), revealing its contribution to the exacerbated inflammatory response clinically observed in envenomated patients.

History of Histamine-Releasing Factor (HRF)/Translationally Controlled Tumor Protein (TCTP) Including a Potential Therapeutic Target in Asthma and Allergy

Histamine-releasing factor (HRF) also known as translationally controlled tumor protein (TCTP) is a highly conserved, ubiquitous protein that has both intracellular and extracellular functions. Here we will highlight the subcloning of the molecule, its clinical implications, as well as an inducible-transgenic mouse. Particular attention will be paid to its extracellular functioning and its potential role as a therapeutic target in asthma and allergy. The cells and the cytokines that are produced when stimulated or primed by HRF/TCTP will be detailed as well as the downstream signaling pathway that HRF/TCTP elicits. While it was originally thought that HRF/TCTP interacted with IgE, the finding that cells not binding IgE also respond to HRF/TCTP called this interaction into question. HRF/TCTP or at least its mouse counterpart appears to interact with some, but not all IgE and IgG molecules. HRF/TCTP has been shown to activate multiple human cells including basophils, eosinophils, T cells, and B cells. Since many of the cells that are activated by HRF/TCTP participate in the allergic response, the extracellular functions of HRF/TCTP could exacerbate the allergic, inflammatory cascade. Particularly exciting is that small molecule agonists of the phosphatase SHIP-1 have been shown to modulate the P13 kinase/AKT pathway and may control inflammatory disorders. This review discusses this possibility in light of HRF/TCTP.

Extracellular translationally controlled tumor protein promotes colorectal cancer invasion and metastasis through Cdc42/JNK/ MMP9 signaling

The translationally controlled tumor protein (TCTP) can be secreted independently of the endoplasmic reticulum/Golgi pathway and has extrinsic activities when it is characterized as the histamine releasing factor (HRF). Despite its important role in allergies and inflammation, little is known about how extracellular TCTP affects cancer progression. In this study, we found that TCTP was overexpressed in the interstitial tissue of colorectal cancer (CRC) and its expression correlated with poor survival, high pathological grades and metastatic TNM stage in CRC patients. TCTP expression was greater in metastatic liver tissue than in primary tumors and was increased in highly invasive CRC cells. We demonstrated that the expression of TCTP was regulated by HIF-1α and its release was increased in response to low serum and hypoxic stress. Recombinant human TCTP (rhTCTP) promoted the migration and invasiveness of CRC cells in vitro and contributed to distant liver metastasis in vivo. Furthermore, rhTCTP activated Cdc42, phosphorylated JNK (p-JNK), increasing the translocation of p-JNK from the cytoplasm to the nucleus, as well as the secretion of MMP9. In addition, the expression of TCTP positively correlated with that of Cdc42 and p-JNK in clinical CRC samples. The silencing of Cdc42, JNK and MMP9 significantly inhibited the Matrigel invasion of rhTCTP-enhanced CRC cells. Collectively, these results identify a new role for extracellular TCTP as a promoter of CRC progression and liver metastases via Cdc42/JNK/MMP9 activation.

Dimerized translationally controlled tumor protein increases interleukin-8 expression through MAPK and NF-κB pathways in a human bronchial epithelial cell line

Background

Histamine releasing factor (HRF) is a unique cytokine known to regulate a variety of immune cells in late allergic reactions. In the previous study, we revealed that the biologically active form of HRF is the dimerized translationally controlled tumor protein (dTCTP) for the first time, and confirmed the secretion of IL-8 cytokine by dTCTP in human bronchial epithelial cells. However, the signaling pathway by which dTCTP promotes the secretion of IL-8 is not known.

Results

When the cells were stimulated with dTCTP, the canonical NF-κB pathway and ERK, JNK and p38 MAPK become activated. dTCTP promoted transcription of IL-8, which involved NF-κB and AP-1 transcription factors. NF-κB was found to be essential for the transcriptional activation of IL-8, while AP-1 was partially responsible for the transcriptional activation by dTCTP. p38 MAPK was found to be involved in post-transcriptional regulation of dTCTP by stabilizing IL-8 mRNA.

Conclusions

This study demonstrated that dTCTP induces IL-8 secretion in BEAS-2B cells through transcriptional and post-transcriptional regulation of MAPK and NF-κB pathways. This study provides insight into the mechanism by which dTCTP induces inflammation.

Fortilin: A Potential Target for the Prevention and Treatment of Human Diseases

Fortilin is a highly conserved 172-amino-acid polypeptide found in the cytosol, nucleus, mitochondria, extracellular space, and circulating blood. It is a multifunctional protein that protects cells against apoptosis, promotes cell growth and cell cycle progression, binds calcium (Ca²⁺) and has antipathogen activities. Its role in the pathogenesis of human and animal diseases is also diverse. Fortilin facilitates the development of atherosclerosis, contributes to both systemic and pulmonary arterial hypertension, participates in the development of cancers, and worsens diabetic nephropathy. It is important for the adaptive expansion of pancreatic β-cells in response to obesity and increased insulin requirement, for the regeneration of liver after hepatectomy, and for protection of the liver against alcohol- and ER stress-induced injury. Fortilin is a viable surrogate marker for in vivo apoptosis, and it plays a key role in embryo and organ development in vertebrates. In fish and shrimp, fortilin participates in host defense against bacterial and viral pathogens. Further translational research could prove fortilin to be a viable molecular target for treatment of various human diseases including and not limited to atherosclerosis, hypertension, certain tumors, diabetes mellitus, diabetic nephropathy, hepatic injury, and aberrant immunity and host defense.

Immunization of mice with Plasmodium TCTP delays establishment of Plasmodium infection

Translationally controlled tumour protein (TCTP) may play an important role in the establishment or maintenance of parasitemia in a malarial infection. In this study, the potential of TCTP as a malaria vaccine was investigated in two trials. In the initial vaccine trial, Plasmodium falciparum TCTP (PfTCTP) was expressed in Saccharomyces cerevisiae and used to immunize BALB/c mice. Following challenge with Plasmodium yoelii YM, parasitemia was significantly reduced during the early stages of infection. In the second vaccine trial, the TCTP from P. yoelii and P. berghei was expressed in Escherichia coli and used in several mouse malaria models. A significant reduction in parasitemia in the early stages of infection was observed in BALB/c mice challenged with P. yoelii YM. A significantly reduced parasitemia at each day leading up to a delayed and reduced peak parasitemia was also observed in BALB/c mice challenged with the nonlethal Plasmodium chabaudi (P.c.) chabaudi AS. These results suggest that TCTP has an important role for parasite establishment and may be important for pathogenesis.

The first characterization of gene structure and biological function for echinoderm translationally controlled tumor protein (TCTP)

Translationally controlled tumor protein (TCTP) is a multifunctional protein that existed ubiquitously in different eukaryote species and distributed widely in various tissues and cell types. In this study, the gene structure and biological function of TCTP were first characterized in echinoderm. An echinoderm TCTP named StmTCTP was identified from sea cucumber (Stichopus monotuberculatus) by expression sequence tag (EST) analysis and rapid amplification of cDNA ends (RACE) approach. The StmTCTP cDNA is 1219 bp in length, containing a 5'-untranslated region (UTR) of 77 bp, a 3'-UTR of 623 bp and an open reading frame (ORF) of 519 bp that encoding a protein of 172 amino acids with a deduced molecular weight of 19.80 kDa and a predicted isolectric point of 4.66. Two deduced signal signatures termed TCTP1 and TCTP2, a microtubule binding domain, a Ca(2+) binding domain and the conserved residues forming Rab GTPase binding surface were found in the StmTCTP amino acid sequence. For the gene structure, StmTCTP contains four exons separated by three introns. The anti-oxidation and heat shock protein activities of recombinant TCTP protein were also demonstrated in this study. In addition, the expression of StmTCTP was found to be significantly upregulated by polyriboinosinic polyribocytidylic acid [poly (I:C)], lipopolysaccharides (LPS) or inactivated bacteria challenge in in vitro primary culture experiments of coelomocytes, suggested that the sea cucumber TCTP might play critical roles not only in the defense against oxidative and thermal stresses, but also in the innate immune defense against bacterial and viral infections.

Surfactant protein SP-D modulates activity of immune cells: proteomic profiling of its interaction with eosinophilic cells

Surfactant protein D (SP-D), a C-type lectin, is known to protect against lung infection, allergy and inflammation. Its recombinant truncated form comprising homotrimeric neck and CRD region (rhSP-D) has been shown to bring down specific IgE levels, eosinophilia and restore Th2-Th1 homeostasis in murine models of lung hypersensitivity. SP-D knockout mice show intrinsic hypereosinophilia and airway hyper-responsiveness that can be alleviated by rhSP-D. The rhSP-D can bind activated eosinophils, inhibit chemotaxis and degranulation, and selectively induce oxidative burst and apoptosis in sensitized eosinophils. A global proteomics study of rhSP-D-treated eosinophilic cell line AML14.3D10 identified large-scale molecular changes associated with oxidative burst, cell stress and survival-related proteins potentially responsible for apoptosis induction. The data also suggested an involvement of RNA binding- and RNA splicing-related proteins. Thus, the proteomics approach yielded a catalog of differentially expressed proteins that may be protein signatures defining mechanisms of SP-D-mediated maintenance of homeostasis during allergy.

TCTP as therapeutic target in cancers

The translationally controlled tumor protein (TCTP) is a highly conserved protein present in eukaryotic organisms. This protein, located both in the cytoplasmic and the nucleus, is expressed in various tissues and is regulated in response to a wide range of extracellular stimuli. TCTP interacts with itself and other protein including MCL1 and p53. TCTP has been shown to play an important role in physiological events, such as cell proliferation, cell death and immune responses but also in stress response and tumor reversion. Moreover, TCTP expression is associated with malignancy and chemoresistance. In this review, we will evaluate pathways regulated by TCTP and current inhibitory strategy to target TCTP in cancerous diseases.

IgE-based immunotherapy of cancer: challenges and chances

Passive immunotherapy with monoclonal antibodies is an indispensable cornerstone of clinical oncology. Notably, all FDA-approved antibodies comprise the IgG class, although numerous research articles proposed monoclonal antibodies of the IgM, IgG, IgA and IgE classes directed specifically against tumor-associated antigens. In particular, for the IgE isotype class, several recent studies could demonstrate high tumoricidic efficacy. Therefore, this review specifically highlights the latest developments toward IgE-based immunotherapy of cancer. Possible mechanisms and safety aspects of IgE-mediated tumor cell death are discussed with special focus on the attracted immune cells. An outlook is given on how especially comparative oncology could contribute to further developments. Humans and dogs have a highly comparable IgE biology, suggesting that translational AllergoOncology studies in patients with canine cancer could have predictive value for the potential of IgE-based anticancer immunotherapy in human clinical oncology.

The C-terminal cysteine of turbot Scophthalmus maximus translationally controlled tumour protein plays a key role in antioxidation and growth-promoting functions

The translationally controlled tumour protein (TCTP) of turbot Scophthalmus maximus (SmTCTP) contains only one cysteine (Cys¹⁷⁰) at the C-terminal end. The biological role of this C-terminal Cys¹⁷⁰ in the antioxidation and growth-promoting functions of SmTCTP was examined by site-directed mutation of C170A (Cys¹⁷⁰ →Ala¹⁷⁰). It was found that C170A mutation not only obviously decreased the antioxidation capacity of the mutant-smtctp-transformed bacteria exposed to 0·22 mM hydrogen peroxide, but also significantly interrupted the normal growth and survival of the mutant-smtctp-transformed bacteria and flounder Paralichthys olivaceus gill (FG) cells, indicating a key role played by Cys¹⁷⁰ in the antioxidation and growth-promoting functions of SmTCTP. This study also suggested that the self-dimerization or dimerization with other interacting proteins is critical to the growth-promoting function of SmTCTP.

Histamine-releasing factor and immunoglobulins in asthma and allergy

Factors that can induce the release of histamine from basophils have been studied for more than 30 years. A protein termed histamine-releasing factor (HRF) was purified and molecularly cloned in 1995. HRF can stimulate histamine release and IL-4 and IL-13 production from IgE-sensitized basophils and mast cells. HRF-like activities were found in bodily fluids during the late phase of allergic reactions, implicating HRF in allergic diseases. However, definitive evidence for the role of HRF in allergic diseases has remained elusive. On the other hand, we found effects of monomeric IgE on the survival and activation of mast cells without the involvement of a specific antigen, as well as heterogeneity of IgEs in their ability to cause such effects. The latter property of IgE molecules seemed to be similar to the heterogeneity of IgEs in their ability to prime basophils in response to HRF. This similarity led to our recent finding that ~30% of IgE molecules can bind to HRF via their Fab interactions with two binding sites within the HRF molecule. The use of peptide inhibitors that block HRF-IgE interactions revealed an essential role of HRF to promote skin hypersensitivity and airway inflammation. This review summarizes this and more recent findings and provides a perspective on how they impact our understanding of allergy pathogenesis and potentially change the treatment of allergic diseases.

A new antiallergic agent that binds to dimerized translationally controlled tumor protein and inhibits allergic symptoms is nontoxic

Dimerized translationally controlled tumor protein (dTCTP) plays a role in allergic diseases. A 7-mer peptide, dimerized translationally binding protein 2 (dTBP2), binds to dTCTP and inhibits dTCTP, suggesting that the 7-mer peptide may have therapeutic potential. We assessed the safety of dTBP2 by examining its cytotoxicity to both human bronchial epithelial cells and mice. dTBP2 did not cause cytotoxicity to the epithelial cells in concentrations up to 100 μg/ml. Also, dTBP2 caused no adverse effects upon repeated administration of 50 mg/kg over 24 h to mice. Hence, we conclude that dTBP2 is a safe candidate drug for use in the therapy of allergic diseases.

Brown spider (Loxosceles genus) venom toxins: tools for biological purposes

Venomous animals use their venoms as tools for defense or predation. These venoms are complex mixtures, mainly enriched of proteic toxins or peptides with several, and different, biological activities. In general, spider venom is rich in biologically active molecules that are useful in experimental protocols for pharmacology, biochemistry, cell biology and immunology, as well as putative tools for biotechnology and industries. Spider venoms have recently garnered much attention from several research groups worldwide. Brown spider (Loxosceles genus) venom is enriched in low molecular mass proteins (5–40 kDa). Although their venom is produced in minute volumes (a few microliters), and contain only tens of micrograms of protein, the use of techniques based on molecular biology and proteomic analysis has afforded rational projects in the area and permitted the discovery and identification of a great number of novel toxins. The brown spider phospholipase-D family is undoubtedly the most investigated and characterized, although other important toxins, such as low molecular mass insecticidal peptides, metalloproteases and hyaluronidases have also been identified and featured in literature. The molecular pathways of the action of these toxins have been reported and brought new insights in the field of biotechnology. Herein, we shall see how recent reports describing discoveries in the area of brown spider venom have expanded biotechnological uses of molecules identified in these venoms, with special emphasis on the construction of a cDNA library for venom glands, transcriptome analysis, proteomic projects, recombinant expression of different proteic toxins, and finally structural descriptions based on crystallography of toxins.

A peptide binding to dimerized translationally controlled tumor protein modulates allergic reactions

Translationally controlled tumor protein (TCTP) is believed to be involved in a variety of inflammatory processes: secretion of histamine and cytokines such as IL-4, IL-8, IL-13, and granulocyte/macrophage colony-stimulating factor; chemoattraction for eosinophils; augmentation of B cell proliferation; and immunoglobulin production, thereby potentially regulating allergic phenomena. In a previous study, we showed that the cytokine-releasing activity of extracellular TCTP is generated only when TCTP dimerizes via the intermolecular disulfide bond of NH(2)-terminal truncated TCTP implying that the dimerized TCTP (dTCTP) promotes the inflammatory phenomena. Modulation of dTCTP, thus, may offer a strategy for the treatment of chronic allergic diseases. In this study, we searched for dTCTP-binding peptides (dTBPs) by screening a phage-displayed 7-mer peptide library. We identified one peptide in the library, designated as dTBP2, which showed higher affinity to dTCTP than to full-length, monomeric TCTP. dTBP2 inhibited the induction of IL-8 by dTCTP from BEAS-2B cells. dTBP2 also reduced symptom score and eosinophil infiltration in a mouse rhinitis model. This study suggests that the dTBP2 binding to dTCTP modulates the release of inflammatory mediators of dTCTP. This result may provide a rational strategy for the treatment of allergic diseases.

Minimal change nephrotic syndrome in a patient with strongyloidiasis

Strongyloidiasis, a chronic infection caused by the intestinal parasite Strongyloides stercoralis, is prevalent in the Nansei Islands of Japan. Here, we report our findings on a case of strongyloidiasis complicated with steroid-resistant minimal change nephrotic syndrome in a 69-year-old male resident of Fukuoka Prefecture who had lived in Yakushima, one of the Nansei Islands, until age 15. In October 2006, he developed proteinuria and edema, and was diagnosed with minimal change nephrotic syndrome on the basis of the renal biopsy findings. Following treatment with prednisolone, the level of proteinuria decreased to 0.29 g/day by day 35. However, 5 days later (day 40), the patient developed persistent watery diarrhea and vomiting, leading to dehydration and malnutrition. Pneumonia and bacterial meningitis subsequently developed (day 146); filarial (infectious-type) and rhabditiform (noninfectious-type) S. stercoralis larvae were detected for the first time in the patient's sputum, gastric juice, feces, and urine. Although treatment with ivermectin was started immediately and the parasitosis responded to the treatment, the patient died of sepsis. Consequently, although strongyloidiasis is a rare infection except in endemic regions, it is essential to consider the possibility of this disease and begin treatment early for patients who have lived in endemic areas and who complain of unexplained diarrhea during steroid-induced or other immunosuppression.

The effects of overexpression of histamine releasing factor (HRF) in a transgenic mouse model

BACKGROUND

Asthma is a disease that affects all ages, races and ethnic groups. Its incidence is increasing both in Westernized countries and underdeveloped countries. It involves inflammation, genetics and environment and therefore, proteins that exacerbate the asthmatic, allergic phenotype are important. Our laboratory purified and cloned a histamine releasing factor (HRF) that was a complete stimulus for histamine and IL-4 secretion from a subpopulation of allergic donors' basophils. Throughout the course of studying HRF, it was uncovered that HRF enhances or primes histamine release and IL-13 production from all anti-IgE antibody stimulated basophils. In order to further delineate the biology of HRF, we generated a mouse model.

METHODOLOGY/PRINCIPAL FINDINGS

We constructed an inducible transgenic mouse model with HRF targeted to lung epithelial cells, via the Clara cells. In antigen naïve mice, overproduction of HRF yielded increases in BAL macrophages and statistical increases in mRNA levels for MCP-1 in the HRF transgenic mice compared to littermate controls. In addition to demonstrating intracellular HRF in the lung epithelial cells, we have also been able to document HRF's presence extracellularly in the BAL fluid of these transgenic mice. Furthermore, in the OVA challenged model, we show that HRF exacerbates the allergic, asthmatic responses. We found statistically significant increases in serum and BAL IgE, IL-4 protein and eosinophils in transgenic mice compared to controls.

CONCLUSIONS/SIGNIFICANCE

This mouse model demonstrates that HRF expression enhances allergic, asthmatic inflammation and can now be used as a tool to further dissect the biology of HRF.

Molecular cloning and expression characterization of translationally controlled tumor protein in silkworm pupae

A Bombyx mori (B. mori) cDNA was isolated from silkworm pupae cDNA library encoding a homologue of translationally controlled tumor protein (BmTCTPk). BmTCTPk was expressed in E. coli; SDS-PAGE and Western blot showed the molecular weight of recombinant and native BmTCTPk is approximately 28 and 25 kDa, respectively; they are larger than the theoretical molecular weight. Immunohistochemical studies showed that BmTCTPk is uniformly distributed throughout the cytoplasm of BmN cells. In silkworm pupae, BmTCTPk is expressed in the midgut wall, the midgut cavity, and some fat body tissues lying between the midgut wall and body wall. Western blot and ELISAs performed on total protein extracts isolated from silkworm pupae at different development stages showed that, although BmTCTPk is expressed during all pupae stages, its expression level increases dramatically during late pupae stages, suggesting that BmTCTPk may play an important role during the developmental transition from pupa to imago.

Alternaria alternata TCTP, a novel cross-reactive ascomycete allergen

Defining more comprehensively the allergen repertoire of the ascomycete Alternaria alternata is undoubtedly of immense medical significance since this mold represents one of the most important, worldwide occurring fungal species responsible for IgE-mediated hypersensitivity reactions ranging from rhinitis and ocular symptoms to severe involvement of the lower respiratory tract including asthma with its life-threatening complications. Performing a hybridization screening of an excised A. alternata cDNA library with a radioactively labeled Cladosporium herbarum TCTP probe, we were able to identify, clone and purify the respective A. alternata homologue of TCTP which again represents a multifunctional protein that has been evolutionarily conserved from unicellular eukaryotes like yeasts to humans and appears, summarizing current literature, to be involved in housekeeping processes such as cell growth as well as cell-cycle progression, the protection of cells against various stress conditions including for instance apoptosis, and in higher organisms even in the allergic response. In this context, our present study characterizes recombinant A. alternata TCTP as a novel minor allergen candidate that displays a prevalence of IgE reactivity of approximately 4% and interestingly shares common, cross-reactive IgE epitopes with its C. herbarum and human counterparts as determined via Western blotting and in vitro inhibition approaches.

Proton pump inhibitors exert anti-allergic effects by reducing TCTP secretion

BACKGROUND

Extracellular translationally controlled tumor protein (TCTP) is known to play a role in human allergic responses. TCTP has been identified outside of macrophages, in activated mononuclear cells, and in biological fluids from allergic patients. Even TCTP devoid of signal sequences, is secreted to extracellular environment by an yet undefined mechanism. This study is aimed at understanding the mechanism of TCTP release and its regulation. A secondary goal is to see if inhibitors of TCTP release can serve as potential anti-allergic asthmatic drugs.

METHODOLOGY/PRINCIPAL FINDINGS

Using Western blotting assay in HEK293 and U937 cells, we found that TCTP secretion is reduced by omeprazole and pantoprazole, both of which are proton pump inhibitors. We then transfected HEK293 cells with proton pump expression vectors to search for the effects of exogeneously overexpressed H(+)/K(+)-ATPase on the TCTP secretion. Based on these in vitro data we checked the in vivo effects of pantoprazole in a murine model of ovalbumin-induced allergy. Omeprazole and pantoprazole reduced TCTP secretion from HEK293 and U937 cells in a concentration-dependent fashion and the secretion of TCTP from HEK293 cells increased when they over-expressed H(+)/K(+)-ATPase. In a murine model of ovalbumin-induced allergy, pretreatment with pantoprazole reduced infiltration of inflammatory cells, increased goblet cells, and increased TCTP secretion induced by OVA challenge.

CONCLUSION

Since Omeprazole and pantoprazole decrease the secretion of TCTP which is associated with the development of allergic reaction, they may have the potential to serve as anti-allergic (asthmatic) drugs.

Histamine-releasing factor/translationally controlled tumor protein (HRF/TCTP)-induced histamine release is enhanced with SHIP-1 knockdown in cultured human mast cell and basophil models

Previously, we demonstrated a negative correlation between histamine release to histamine-releasing factor/translationally controlled tumor protein (HRF/TCTP) and protein levels of SHIP-1 in human basophils. The present study was conducted to investigate whether suppressing SHIP-1 using small interfering (si)RNA technology would alter the releasability of culture-derived mast cells and basophils, as determined by HRF/TCTP histamine release. Frozen CD34+ cells were obtained from the Fred Hutchinson Cancer Research Center (Seattle, WA, USA). Cells were grown in StemPro-34 medium containing cytokines: mast cells with IL-6 and stem cell factor (100 ng/ml each) for 6-8 weeks and basophils with IL-3 (6.7 ng/ml) for 2-3 weeks. siRNA transfections were performed during Week 6 for mast cells and Week 2 for basophils with siRNA for SHIP-1 or a negative control siRNA. Changes in SHIP-1 expression were determined by Western blot. The functional knockdown was measured by HRF/TCTP-induced histamine release. siRNA knockdown of SHIP-1 in mast cells ranged from 31% to 82%, mean 65 +/- 12%, compared with control (n=4). Histamine release to HRF/TCTP was increased only slightly in two experiments. SHIP-1 knockdown in basophils ranged from 34% to 69%, mean 51.8 +/- 7% (n=4). Histamine release to HRF/TCTP in these basophils was dependent on the amount of SHIP knockdown. Mast cells and basophils derived from CD34+ precursor cells represent suitable models for transfection studies. Reducing SHIP-1 protein in cultured mast cells and in cultured basophils increases releasability of the cells.

Distinct characteristics of signal transduction events by histamine-releasing factor/translationally controlled tumor protein (HRF/TCTP)-induced priming and activation of human basophils

We previously identified a negative correlation between histamine release to histamine releasing factor/translationally controlled tumor protein (HRF/TCTP) and protein levels of the Src homology 2 domain-containing inositol 5' phosphatase (SHIP) in basophils. We have also demonstrated that HRF/TCTP primes basophils to release mediators. The purpose of this study was to begin characterization of signal transduction events directly induced by HRF/TCTP and to investigate these events when HRF/TCTP is used as a priming agent for human basophil histamine release. Highly purified human basophils were examined for surface expression of bound HRF/TCTP, changes in calcium, and phosphorylation of Akt, mitogen-activated protein kinase kinase (MEK), extracellular signal-regulated kinase (ERK), Syk, and FcepsilonRIgamma. Results showed that basophils from all donors bound HRF/TCTP. There was a biphasic calcium response to HRF/TCTP, which corresponded to the magnitude of histamine release. Furthermore, those donors who have direct histamine release when exposed to HRF/TCTP (HRF/TCTP responder [HRF/TCTP-R] donors) have phosphorylation of Syk, Akt, MEK, and ERK. Remarkably, basophils from HRF/TCTP-nonresponder (HRF/TCTP-NR) donors do not show phosphorylation of these molecules. This finding is different from IL-3, which also primes basophils for histamine release, but does show phosphorylation of these events. We conclude that priming induced by HRF/TCTP is distinct from that induced by IL-3.

Induction of translationally controlled tumor protein (TCTP) by transcriptional and post-transcriptional mechanisms

Expression of the human TPT1 gene coding for translationally controlled tumor protein (TCTP) was investigated in Calu-6 and Cos-7 cells under the influence of 4beta-phorbol 12-myristate 13-acetate (PMA), forskolin, dioxin and the heavy metals copper, nickel and cobalt. Transcriptional and post-transcriptional aspects of the mechanism were analyzed by TCTP mRNA/protein quantification, luciferase reporter gene assays depending on TPT1 promoter sequences or TCTP mRNA 5'/3'-UTRs and investigation of the interaction of RNA-binding proteins with UTRs by UV-crosslinking. PMA, forskolin, dioxin, cobalt and nickel induced TCTP expression in 24 h in both cell lines about 2.2-3.2-fold at the mRNA level and 1.6-2.2-fold at the protein level. The highest induction rate, 4.5-5.0-fold at the mRNA level and 3.5-4.0-fold at the protein level, was observed with copper. TPT1 promoter assays showed transcriptional activation by PMA, forskolin and dioxin (2.0-3.1-fold) and a 7.0-8.0-fold increase by copper, whereas cobalt and nickel had no effect. Deletion analysis revealed that copper-dependent transcriptional control was transmitted by a metal-responsive element residing in the TPT1 promoter. Post-transcriptional activation of TCTP expression was associated with the action of dioxin, nickel, cobalt (1.8-2.3-fold) and copper (2.5-3.0-fold), whereas stimulation of TCTP synthesis by copper was mediated by the TCTP mRNA 3'-UTR (3.2-fold) but not by the 5'-UTR (0.5-fold). mRNA stabilization was found to mediate these effects of cobalt and nickel. Post-transcriptional regulation was associated with qualitative and quantitative changes in the binding of specific RNA-binding proteins to UTRs.

Solution structure and mapping of a very weak calcium-binding site of human translationally controlled tumor protein by NMR

Human translationally controlled tumor protein (TCTP) is a growth-related, calcium-binding protein. We determined the solution structure and backbone dynamics of human TCTP, and identified the calcium-binding site of human TCTP using multi-dimensional NMR spectroscopy. The overall structure of human TCTP has a rather rigid well-folded core and a very flexible long loop connected by a short two-strand beta-sheet, which shows a conserved fold in the TCTP family. The C-terminal portions of loop L(alpha3beta8) and strand beta9 and the N-terminal region of strand beta8 may form a calcium-binding site in the human TCTP structure, which is largely conserved in the sequence alignment of TCTPs. The K(d) value for the calcium binding is 0.022-0.025 M indicating a very weak calcium-binding site.

Cladosporium herbarum translationally controlled tumor protein (TCTP) is an IgE-binding antigen and is associated with disease severity

Cladosporium herbarum represents one of the most important world-wide occurring allergenic fungal species. The prevalence of IgE reactivity to C. herbarum in patients suffering from allergy varies between 5 and 30% in the different climatic zones. Since mold allergy has often been associated with severe asthma, along with other allergic symptoms, it is important to define more comprehensively the allergen repertoire of this ascomycete. In this context we are reporting our successful approach to identify, clone, produce as a recombinant protein, purify and further characterize a new C. herbarum allergen which is a close homolog of the human translationally controlled tumor protein (TCTP, also called histamine releasing factor, HRF). The immunoreactivity of both pure recombinant molecules was investigated by means of immunoblot analyses, enzyme-linked immunosorbent assays as well as histamine release studies. To summarize, IgE antibodies from five out of nine individuals recognized both the human and the fungal protein in immunoblots. The latter was able to cause histamine release from human basophils with about half the efficiency compared to its human homolog HRF. Cross-inhibition assays showed that the patients' IgEs recognize common epitopes on both the human and C. herbarum proteins, but however, only pre-incubation with C. herbarum TCTP could completely inhibit reactivity with HRF. Furthermore, it appears that patients reactive to TCTP have a higher probability to suffer from asthma than other allergic patients.

Immunological cross-reactivity analysis on recombinant histamine-releasing factors from Schistosoma japonicum, Clonorchis sinensis, and Wistar rat

Studies have demonstrated a declined incidence of allergic disorders in the population with helminthic infection. Though several hypotheses have been proposed to explain how helminthic infection protected people against allergies, the underlying mechanisms remain poorly understood. A human histamine-releasing factor (HRF) has been proved to be closely related to the development of allergic disorders and the homologues are ubiquitously expressed in all eukaryotic organisms including parasites. To study the role of this HRF in the relationship between parasitic infection and allergic diseases with experimental model of rats, the cDNA of the homologues of the human HRF from Wistar rat, Schistosoma japonicum, and Clonorchis sinensis containing a coding region of 519, 510, and 510 bp, respectively, were cloned. In addition, the cross-reactivity between recombinant rat HRF (rRHRF) and recombinant S. japonicum HRF (rSjHRF) as well as that between rRHRF and recombinant C. sinensis HRF (rCsHRF) was identified with ELISA and Western blotting. Based on their detected cross-reactivities, a hypothesis was put forward that the anti-parasitic HRFs antibodies could inhibit the effects of host HRF and those of parasitic HRFs and thus decreased the host sensitivities to allergens.

Expression of the human TPT1 gene coding for translationally controlled tumor protein (TCTP) is regulated by CREB transcription factors

Re-evaluation of genomic and cDNA data revealed that the human TPT1 gene coding for the translationally controlled tumor protein (TCTP) consists of at least 4211 base pairs. It is transcribed into two transcripts of about 0.8 and 1.2 kb, which contain the same coding region and 5'-UTR, but differ in the length of 3'-UTRs by the use of alternative polyadenylation signals. 459 bp promoter sequences were analyzed by theoretical evaluation, reporter-gene assays, gelshift and footprinting experiments to search for transcription factor binding sites. The promoter contains two highly conserved CRE sites between -50 and -89 in close vicinity to a TATA-box at -30. Supershift assays identified CREB I and Fra II of the CREB/ATF1/AP1 family as factors interacting with the CRE/AP1 site. A 3-5-fold stimulation of TCTP synthesis by forskolin and phorbolester in T24 cells and promoter-reporter experiments using CRE-deletion constructs suggested a transcriptional control by cAMP signaling via phosphorylation dependent activation of CRE/CREB interaction.

Staying alive in adversity: transcriptome dynamics in the stress-resistant dauer larva

In response to food depletion and overcrowding, the soil nematode Caenorhabditis elegans can arrest development and form an alternate third larval stage called the dauer. Though nonfeeding, the dauer larva is long lived and stress resistant. Metabolic and transcription rates are lowered but the transcriptome of the dauer is complex. In this study, distribution analysis of transcript profiles generated by Serial Analysis of Gene Expression (SAGE) in dauer larvae and in mixed developmental stages is presented. An inverse relationship was observed between frequency and abundance/copy number of SAGE tag types (transcripts) in both profiles. In the dauer profile, a relatively greater proportion of highly abundant transcripts was counterbalanced by a smaller fraction of low to moderately abundant transcripts. Comparisons of abundant tag counts between the two profiles revealed relative enrichment in the dauer profile of transcripts with predicted or known involvement in ribosome biogenesis and protein synthesis, membrane transport, and immune responses. Translation-coupled mRNA decay is proposed as part of an immune-like stress response in the dauer larva. An influence of genomic region on transcript level may reflect the coordination of transcription and mRNA turnover.

Expression of immunoglobulin E-dependent histamine-releasing factor in idiopathic nephrotic syndrome of childhood

Concanavarin-A (conA)-stimulated peripheral blood mononuclear cells (PBMNC) from patients with idiopathic nephrotic syndrome (INS) produce putative factors that increase vascular permeability. These factors are expressed in the nephrotic phase but are reduced in the convalescent phase. To identify the genes that are expressed only in the nephrotic phase, we performed cDNA subtraction using conA-stimulated PBMNC from three patients with INS. We isolated several gene transcripts in all three subtracted cDNA libraries. Among these genes, IgE-dependent histamine-releasing factor (HRF) was overexpressed in the nephrotic phase not only at the mRNA level but also at the protein level in another 10 patients with INS. Moreover, we found increased secretion of HRF from conA-stimulated PBMNC in the nephrotic phase. The results suggest that HRF is involved in the pathogenesis of idiopathic nephrotic syndrome.

Evolution and expression of Translationally Controlled Tumour Protein (TCTP) of fish

Translationally Controlled Tumour Protein (TCTP) is one of the abundant and ubiquitously expressed proteins in metazoans. In order to better understand its functions in non-mammalians, cDNA encoding full-length TCTP has been isolated and characterized from a teleost fish, Labeo rohita (rohu). Encoded by a 1043 nucleotide mRNA, rohu TCTP consists of 171 amino acids and is expressed in all organs, except in brain. Secondary structure of fish TCTP mRNAs shows that they could be potential substrates for RNA specific protein kinase PKR. The three-dimensional structure of rohu TCTP has been determined, as the first metazoan model of this protein. The conservational and phylogenic clustering of plant and animal TCTP sequences is consistent with the eukaryotic classification, and is suggestive of early origin for the TCTP ortholog in eukaryote evolution, as early as 1.0 x 10(9) years ago. Despite significant conservation, meticulous sequence analysis reveals striking differences that suggest possible new functions for TCTP.

AnophelesMosquito Bites Activate Cutaneous Mast Cells Leading to a Local Inflammatory Response and Lymph Node Hyperplasia

When Anopheles mosquitoes probe the skin for blood feeding, they inject saliva in dermal tissue. Mosquito saliva is known to exert various biological activities, but its perception by the immune system and its role in parasite transmission remain poorly understood. In the present study, we report on the cellular changes occurring in the mouse skin and draining lymph nodes after a Anopheles stephensi mosquito bite. We show that mosquito bites induce dermal mast cell degranulation, leading to fluid extravasation and neutrophil influx. This inflammatory response does not occur in mast cell-deficient W/W(v) mice, unless these are reconstituted specifically with mast cells. Mast cell activation caused by A. stephensi mosquito bites is followed by hyperplasia of the draining lymph node due to the accumulation of CD3(+), B220(+), CD11b(+), and CD11c(+) leukocytes. The T cell enrichment of the draining lymph nodes results from their sequestration from the circulation rather than local proliferation. These data demonstrate that mosquito bites and very likely saliva rapidly trigger the immune system, emphasizing the critical contribution of peripheral mast cells in inducing T cell and dendritic cell recruitment within draining lymph nodes, a prerequisite for the elicitation of T and B lymphocyte priming.

The translationally controlled tumour protein (TCTP)

The translationally controlled tumour protein (TCTP) is a highly conserved protein that is widely expressed in all eukaryotic organisms. Based on its sequence, TCTP was listed as a separate protein family in protein databases but the recent elucidation of the solution structure of the fission yeast orthologue places it close to a family of small chaperone proteins. The molecular functions determined so far, Ca(2+)- and microtubule-binding, have been mapped to an alpha-helical region of the molecule. TCTP expression is highly regulated both at the transcriptional and translational level and by a wide range of extracellular signals. TCTP has been implicated in important cellular processes, such as cell growth, cell cycle progression, malignant transformation and in the protection of cells against various stress conditions and apoptosis. In addition, an extracellular, cytokine-like function has been established for TCTP, and the protein has been implicated in various medically relevant processes.

Identification of the interaction between the human recombinant histamine releasing factor/translationally controlled tumor protein and elongation factor-1 delta (also known as eElongation factor-1B beta)

The human recombinant histamine releasing factor (HrHRF), also known as translationally controlled tumor protein (TCTP), p23 and fortilin, has been described to have both extra- and intracellular functions. To elucidate an extra- or intracellular role for HrHRF, we used the yeast two-hybrid system with HrHRF as the bait and a Jurkat T cell library. We isolated a partial cDNA clone of the human elongation factor-1 delta (EF-1delta) encoding for amino acids 12 to 281. This interaction was confirmed by co-immunoprecipitation experiments. Previously, both HrHRF and EF-1delta have been isolated and identified in association with malignancy in numerous studies. EF-1delta is part of the EF-1 complex responsible for kinetic proofreading in protein synthesis. Additionally, DNA microarray data classifies TCTP (HrHRF) as co-regulated with ribosomal proteins and recent structural analysis of TCTP (HrHRF) relates it to a guanine nucleotide-free chaperone. Our findings of an interaction between HrHRF and EF-1delta taken with some of the recently published information concerning the TCTP (HrHRF) mentioned above suggest a possible intracellular role for TCTP/HrHRF.

Inhibition of cytokine gene transcription by the human recombinant histamine-releasing factor in human T lymphocytes

Human recombinant histamine-releasing factor (HrHRF) preincubation enhances the secretion of histamine, IL-4, and IL-13 from FcepsilonRI-stimulated human basophils. In GM-CSF-primed human eosinophils, HrHRF increases IL-8 production. Our recent experiments were designed to evaluate the effects of HrHRF on human T cell cytokine production. Purified T cells were preincubated with GST-tagged HrHRF, followed by stimulation with PMA and A23187 overnight. A partial inhibition of IL-2 and IL-13 production (30 and 75%, respectively) was detected compared with that in cells treated with PMA/A23187 alone. However, the production of IFN-gamma was similar in PMA/A23187 stimulated cells with or without HrHRF. The inhibition of cytokine protein production was dose dependent and specific to the HrHRF portion of GST-HrHRF. The inhibition was not due to endotoxin, since preincubation with polymyxin B and HrHRF gave similar results to that with HrHRF alone. The same pattern and specificity of cytokine regulation were replicated in the Jurkat T cell line as for primary T cells. The PMA/A23187-stimulated activity of a proximal promoter IL-13, IL-4, or IL-2 luciferase construct transfected into Jurkat cells was partially inhibited (60, 32, or 70%, respectively) upon GST-HrHRF preincubation, suggesting that HrHRF functions to inhibit cytokine production in Jurkat cells by preventing gene transcription. The inhibition of IL-2 promoter activation was specific to the HrHRF portion of GST-HrHRF. We conclude that HrHRF, in addition to functioning as a histamine-releasing factor, can differentially modulate the secretion of cytokines from human basophils, eosinophils, T cells, and murine B cells, suggesting that it may induce a complex array of responses at sites of allergic inflammation.

The American dog tick, Dermacentor variabilis, encodes a functional histamine release factor homolog

We have identified a functional Dermacentor variabilis histamine release factor (DVHRF) homolog and shown that it is a secreted tick saliva protein. The 945 base pair (bp) full-length DVHRF cDNA has a 522 bp open reading frame that encodes a 20 kDa (173 amino acid) polypeptide. Sequence analysis showed that the two HRF signature amino acid sequences were conserved in DVHRF, indicating close structural similarity between DVHRF and other characterized HRF homologs. Northern and Western blotting analyses of partially fed and unfed ticks indicates that neither DVHRF transcriptional nor translational regulation were influenced by tick feeding activity. Like its counterparts from the mammalian system, tick DVHRF is expressed in various tissues, as assessed by both Northern and Western blotting analyses. Furthermore, an Escherichia coli-expressed recombinant DVHRF induced histamine secretion from a rat basophilic leukemic cell line in a dose-dependent manner. Extensive experimental evidence has shown that high levels of histamine at tick attachment sites impede the biological success of feeding ticks and, in response, ticks secrete histamine-binding proteins to minimize the adverse effects of histamine. Our results suggest the existence of a tick-derived multifaceted control mechanism for levels of histamine at tick feeding sites.

Histamine-releasing factors, a heterogeneous group of different activities

Histamine-releasing factor or HRF is a collective term used for a heterogeneous group of factors with different modes of action. The current review is focussed on IgE-dependent HRF that require the presence of certain types of IgE (designated IgE+) to induce histamine release. IgE+ might be a structurally different IgE molecule, or, alternatively, autoreactive IgE. A subgroup of IgE-dependent HRF does not bind to IgE, such as cloned HRF p23. This factor turned out to be a basophil-priming cytokine. Alternatively IgE-dependent HRF might be an autoallergen. Several groups demonstrated IgE antibodies to human proteins. However, not all IgE autoallergen-containing extracts induce histamine release of appropriately sensitized basophils. In culture supernatants of human mononuclear cells an autoallergenic activity (Agmn) is found, but no binding to IgE+ was found yet. Agmn might be an autoallergen, since it is cross-reactive with a grass pollen allergen in the stripped basophil assay. IgE-dependent HRF and IgE+ may play a role in the late allergic reaction (LAR). However, IgE+ responsiveness to Agmn (IgEmn+) was not required for a bronchial LAR. IgEmn+ is associated with chronic allergic disease, since the prevalence of IgEmn+ is high in the serum of severe asthmatics and atopic dermatitis patients. Our hypothesis is that exogenous allergens induce IgE antibodies cross-reactive with an endogenous protein. During a LAR, these endogenous proteins are released and the subsequent IgE-mediated reaction prolongs and aggravates the allergic and/or asthmatic symptoms. In conclusion, HRF is a confusing term since it is used for different activities. It might be better to avoid this terminology on and just describe the activity of the factors. Autoallergenic activity is likely to explain most, if not all, IgE-dependent activity.

Lectins interact differentially with purified human eosinophils, cultured cord blood-derived mast cells and the myeloid leukaemic cell line AML14.3D10: induction of interleukin-4 secretion is conserved among granulocytes, but is not proportional to agglutination or lectin-glycoprotein interaction

BACKGROUND

Atopy is closely associated with the cellular T helper type-2 (Th2) phenotype, that is dominated by the pleiotrophic cytokine IL-4. The cellular source of IL-4 has yet to be determined, although basophils have been proposed. Eosinophils and mast cells are likely contenders investigated here, and the eosinophil-like leukaemia line AML14.3D10 is compared to eosinophils as an in vitro culturable model for eosinophils. Lectins can cross-link-specific surface glycoproteins and are found in the ingested (processed foods) and inhaled (airborne pollen grains) human environment. Therefore it is of interest to determine whether lectins can elicit the release of IL-4 from Th2-associated granulocytes other than basophils.

METHOD

This study investigated the ability of eosinophils, AML14.3D10 and mast cells to secrete preformed IL-4 in response to stimulation with lectins, and explored molecular mechanisms underlying the interaction.

RESULTS

Purified eosinophils and basophils, and cultured mast cells and AML14.3D10 cells were incubated with 1 micro m lectin. Agglutination was scored by microscopy. IL-4 secretion was measured by enzyme-linked immunosorbent assay. Biotinylated lectins were used to determine binding to cells by flow cytometry and in lectin blots of sodium dodecyl sulphate (SDS) gels.

DISCUSSION

Purified human eosinophils, AML14.3D10 cells and cultured mast cells secrete IL-4 with a pattern similar to that found in basophils when stimulated with a panel of reactive and unreactive lectins. The lectin SNA induces IL-4 secretion from mast cells and basophils, but not from eosinophils or AML14.3D10. Eosinophils appear to secrete only pre-formed IL-4, whereas mast cells may synthesize IL-4 on ligation with the lectin LCA. Lectins that agglutinate the granulocytes investigated do not necessarily induce secretion of IL-4. Lectins that elicit secretion of IL-4 bind more to eosinophils than unreactive lectins as determined by flow cytometry and lectin blotting of SDS gels.

CONCLUSION

As granulocytes with functions related to that of basophils, eosinophils, AML14.3D10 and cultured mast cells respond to stimulation with lectins similarly to basophils. This emphasizes the possibility that eosinophils and mast cells may be linked in their cellular heritage as the cellular partners, and lectins as ligands, may contribute to the maintenance of a Th2-favoured microenvironment that is thought to underlie the allergic march.

Lack of correlation between bronchial late allergic reaction to Dermatophagoides pteronyssinus and in vitro immunoglobulin E reactivity to histamine-releasing factor derived from mononuclear cells

BACKGROUND

Activity of immunoglobulin (Ig)E-dependent histamine-releasing factor (HRF) is dependent on the IgE molecules bound to the surface of basophils. Sera capable of passively sensitizing basophils to release histamine to HRF were designated IgE+ sera. IgE+ and HRF have been suggested to play a role in late allergic reaction (LAR).

OBJECTIVE

The working hypothesis was tested that IgE+ induces a LAR. Further, activity of HRF produced by mononuclear cells (HRF(mn)) was compared with that of recombinant HRF p23.

METHODS

Atopic patients (n = 82) were bronchially provoked with Dermatophagoides pteronyssinus extract and the change in forced expiratory volume in 1 second was monitored. A LAR was defined as forced expiratory volume in 1 second as percentage of baseline < 80% 4 to 10 hours after allergen challenge. The presence of HRF-responsive IgE in serum was determined using basophils sensitized in vitro by serum.

RESULTS

The presence of HRF(mn)-responsive IgE (IgE(mn+)) in serum was shown not be essential for a LAR: 63% of the patients with a LAR had no IgE(mn+) in their serum. Further, 71% of patients with IgE(mn+) did not have a LAR. HRF(mn) and recombinant HRF p23 were not equivalent in the bioassay: serum of 38 of 82 atopic patients sensitized basophils to release histamine to HRF(mn), whereas this was found with serum of 1 of 82 patients to HRF p23.

CONCLUSIONS

The results do not support the hypothesis that IgE(mn+) induces a LAR, but do not exclude the alternative hypothesis that HRFs are released during a LAR and contribute to asthma severity.

Association of the Src homology 2 domain-containing inositol 5' phosphatase (SHIP) to releasability in human basophils

During the study of the biology of the Human recombinant Histamine Releasing Factor (HrHRF), we uncovered a hyperreleasable phenotype of basophils from HrHRF-responder donors. Basophils from these donors released histamne to HrHRF, IL-3 and D(2)O. While there has been a significant amount of work elucidating signal transduction events in human basophils, the reason for this hyperreleasable phenotype remained illusive. A clue to the releasability of these highly allergic, asthmatic HrHRF-responder donor basophils was demonstrated in studies using SHIP knockout mice. Bone marrow-derived mast cells from the SHIP knockout mice demonstrated hyperreleasability to stimuli through the IgE receptor and alteration of subsequent signal transduction events. We have demonstrated a highly significant negative correlation between the amount of SHIP protein per cell equivalent and maximum histamine release to HrHRF. These results provide a clue to the hyperreleasable phenotype and implicate SHIP as an additional regulator of secretion in human basophils.

Cloning and characterization of a calcium-binding, histamine-releasing protein from Schistosoma mansoni

A homologue of the mammalian translationally controlled tumor protein (TCTP) was cloned from the human parasite Schistosoma mansoni (SmTCTP). Sequence analysis showed that SmTCTP differed from other reported TCTPs in having only one signature sequence. Subsequently, SmTCTP was cloned in a T7 expression system and expressed as a histidine-tagged fusion protein. Recombinant SmTCTP (rSmTCTP) has a molecular mass of approximately 23 kDa with the histidine tag. Further analysis showed that SmTCTP transcripts and protein are expressed in all life cycle stages of the parasite within the vertebrate hosts. Interestingly, antibodies to SmTCTP were present in the sera of mice 9 weeks after infection with S. mansoni. Characterization studies showed that rSmTCTP is a calcium-binding protein that can cause histamine release from basophil/mast cells and induce eosinophil infiltration. These findings suggest that SmTCTP may have an important role in the development of allergic inflammatory responses associated with schistosomiasis and may be a target for new drug development.

Molecular characterization of a calcium binding translationally controlled tumor protein homologue from the filarial parasites Brugia malayi and Wuchereria bancrofti

We have cloned homologues of the mammalian translationally controlled tumor protein (TCTP) from the human filarial parasites Wuchereria bancrofti and Brugia malayi. TCTP genes from B. malayi and W. bancrofti were expressed in a T7 promoter vector as histidine tagged fusion proteins. Both the recombinant B. malayi TCTP (rBm-TCTP) and recombinant W. bancrofti TCTP (rWb-TCTP) have a molecular mass of approximately 28 kDa with the histidine tag. Sequence analyses showed that there is a 98% similarity between the two filarial TCTPs at amino acid levels and are immunologically cross-reactive. Analysis of soluble proteins from various lifecycle stages of B. malayi suggested that the expression of Bm-TCTP might be differentially regulated and occurs in multimeric form. Recombinant TCTP were found to form multimers in solution under non-reducing conditions. The tendency for filarial TCTPs to become multimers was predicted by the presence of the Lupas coiled coil structure in their sequence. Despite the absence of a signal sequence, Bm-TCTP is present abundantly in the excretory/secretions (ES) of microfilariae. Characterization studies showed that both Bm- and Wb-TCTPs are calcium-binding proteins and have histamine-releasing function in vitro. When injected intraperitoneally both the filarial TCTPs induced inflammatory infiltration of eosinophils into the peritoneal cavity of mice suggesting that the filarial TCTPs may have a role in the allergic inflammatory responses associated with filarial infections.