[Application of positron emission tomography in detection of myocardial glucose metabolism in rabbit cardiac arrest models].

OBJECTIVE: To investigate the changes of myocardial glucose metabolism in rabbit cardiac arrest models and the effect of hydrogen intervention by 18F-fluroro-2-deoxyglucose (18F-FDG) positron emission tomography (PET) imaging.
 Methods: Fifteen male New Zealand white rabbits were randomly divided into a hydrogen group (n=6), a control group (n=6) and a sham group (n=3). Cardiac arrest (CA) was induced by intravenous injection of potassium chloride. Conventional cardiopulmonary resuscitation (CPR) was initiated after five-minutes CA. The hydrogen group and the control group were mechanically ventilated into mixed gas with 4% hydrogen+96% oxygen and pure oxygen, respectively, for 30 minutes after CPR. Rats in the sham group was performed the same surgical procedure and was injected adrenaline and potassium chloride but did not induce CA. The vital signs at basic state and 30 min after return of spontaneous circulation (ROSC) were recorded in each group. The parameters of CPR were recorded in two CA groups. Myocardial glucose metabolism was assessed by positron emission tomography (PET) at basic state, 2 h and 24 h after ROSC. The maximum standardized uptake value (SUVmax) of 18F-FDG was measured.
 Results: There were no significant differences in the basal body weight and vital signs among the three groups. There was no significant difference in the blood glucose level before PET examination. The 18F-FDG SUVmax in the sham group at three time points was not significantly changed. In the hydrogen group and the control group, the 18F-FDG SUVmax at 2 h after ROSC were significantly higher than the basic level (1.89±0.47 vs 3.47±1.24 and 1.90±0.36 vs 4.26±0.80, respectively). Compared with the control group, the 18F-FDG SUVmax in the hydrogen group was lower at the point at 2 h after ROSC. The 18F-FDG SUVmax in the 2 CA group were down to the basic level at 24 h after ROSC (hydrogen group 2.02±0.64, control group 2.07±0.61).
 Conclusion: Myocardial glucose metabolism in CA rabbits was increased significantly after ROSC, and hydrogen intervention can reduce the degree of glucose metabolism.

IL-25 augments type 2 immune responses by enhancing the expansion and functions of TSLP-DC-activated Th2 memory cells.

Interleukin (IL) 25 (IL-17E), a distinct member of the IL-17 cytokine family, plays important roles in evoking T helper type 2 (Th2) cell-mediated inflammation that features the infiltrations of eosinophils and Th2 memory cells. However, the cellular sources, target cells, and underlying mechanisms remain elusive in humans. We demonstrate that human Th2 memory cells expressing distinctive levels of IL-25 receptor (R) are one of the responding cell types. IL-25 promotes cell expansion and Th2 cytokine production when Th2 central memory cells are stimulated with thymic stromal lymphopoietin (TSLP)-activated dendritic cells (DCs), homeostatic cytokines, or T cell receptor for antigen triggering. The enhanced functions of Th2 memory cells induced by IL-25 are associated with sustained expression of GATA-3, c-MAF, and JunB in an IL-4-independent manner. Although keratinocytes, mast cells, eosinophils, and basophils express IL-25 transcripts, activated eosinophils and basophils from normal and atopic subjects were found to secrete bioactive IL-25 protein, which augments the functions of Th2 memory cells. Elevated expression of IL-25 and IL-25R transcripts was observed in asthmatic lung tissues and atopic dermatitis skin lesions, linking their possible roles with exacerbated allergic disorders. Our results provide a plausible explanation that IL-25 produced by innate effector eosinophils and basophils may augment the allergic inflammation by enhancing the maintenance and functions of adaptive Th2 memory cells.

Herpesvirus saimiri encodes a new cytokine, IL-17, which binds to a novel cytokine receptor.

Herpesvirus Saimiri gene 13 (HVS13) exhibits 57% identity with the predicted sequence of a T cell-derived molecule termed CTLA8. Recombinant HVS13 and CTLA8 stimulate transcriptional factor NF-kappaB activity and Interleukin-6 (IL-6) secretion in fibroblasts, and costimulate T cell proliferation. An HVS13.Fc fusion protein was used to isolate a cDNA encoding a novel receptor that also binds CTLA8. This receptor is unrelated to previously identified cytokine receptor families. A recombinant soluble receptor inhibited T cell proliferation and IL-2 production induced by PHA, concanavalin A (conA), and anti-TCR MAb. These results define CTLA8 and HVS13 as novel cytokines that bind to a novel cytokine receptor. We propose to call these molecules IL-17, vIL-17, and IL-17R, respectively.

Plasmacytoid dendritic cell-specific receptor ILT7-Fc epsilonRI gamma inhibits Toll-like receptor-induced interferon production.

Immunoglobulin-like transcripts are a family of inhibitory and stimulatory cell surface immune receptors. Transcripts for one member of this family, ILT7, are selectively expressed in human plasmacytoid dendritic cells (pDCs). We demonstrate here that ILT7 protein associates with the signal adapter protein Fc epsilonRI gamma to form a receptor complex. Using an anti-ILT7 monoclonal antibody, we show that ILT7 is expressed specifically on human pDCs, but not on myeloid dendritic cells or other peripheral blood leukocytes. Cross-linking of ILT7 resulted in phosphorylation of Src family kinases and Syk kinase and induced a calcium influx in freshly isolated pDCs, which was blocked by Src family and Syk kinases inhibitors, thus indicating the activation of an immunoreceptor-based tyrosine activation motif-mediated signaling pathway. ILT7 cross-linking on CpG or influenza virus-stimulated primary pDCs inhibited the transcription and secretion of type I interferon and other cytokines. Therefore, the ILT7-Fc epsilonRI gamma receptor complex negatively regulates the innate immune functions of human pDCs.

Spontaneous rupturing of splenic artery aneurysm: Another reason for fatal syncope and shock (Case report and literature review).

Splenic artery aneurysm (SAA) is a rare condition; however, it is one of the most common intra-abdominal aneurysm. In the emergency department (ED), due to an uncommon cause of shock and syncope in SAA, it poses great diagnostic challenge for emergency physicians. Here we reported a case of spontaneous rupturing of SAA. A 47-year-old man presented to the ED for syncope and shock. As he had unstable hemodynamic, we gave him fluid resuscitation and point-of-care ultrasound (POCUS), free intraperitoneal fluid was identified on ultrasound, then hemorrhagic ascites was identified by a diagnostic abdominal paracentesis. The rare but life-threatening diagnosis of spontaneous rupturing of SAA was confirmed by contrast-enhanced Computed Tomography and surgery. Spontaneous SAA rupturing is a rare fatal condition which needs immediate diagnosis and management to achieve a favorable outcome. Though there are no risk factors, emergency physicians should consider SAA in the differential diagnosis of sudden collapse. Also, as an emergency physician, it is very important to be a master of first aid skills such as POCUS and treat patients according to the process.

FDG-PET/CT Assessment of the Cerebral Protective Effects of Hydrogen in Rabbits with Cardiac Arrest.

BACKGROUND: Anatomical imaging methods and histological examinations have limited clinical value for early monitoring of brain function damage after cardiac arrest (CA) in vivo. OBJECTIVE: We aimed to assess the cerebral protective effects of hydrogen in rabbits with CA by using fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT). METHODS: Male rabbits were divided into the hydrogen-treated (n=6), control (n=6), and sham (n=3) groups. Maximum standardized uptake values (SUVmax) were measured by FDG-PET/CT at baseline and post-resuscitation. Blood Ubiquitin C-terminal hydrolase-L1 (UCH-L1) and neuron-specific enolase (NSE) were measured before and after the operation. After surgical euthanasia, brain tissues were extracted for Nissl staining. RESULTS: SUVmax values first decreased at 2 and 24 h after resuscitation before rising in the hydrogentreated and control groups. SUVmax values in the frontal, occipital, and left temporal lobes and in the whole brain were significantly different between the hydrogen and control groups at 2 and 24 h postresuscitation (P<0.05). The neurological deficit scores at 24 and 48 h were lower in the hydrogentreated group (P<0.05). At 24 h, the serum UCH-L1 and NSE levels were increased in the hydrogen and control groups (P<0.05), but not in the sham group. At 48 and 72 h post-CA, the plasma UCH-L1 and NSE levels in the hydrogen and control groups gradually decreased. Neuronal damage was smaller in the hydrogen group compared to the control group at 72 h. CONCLUSION: FDG-PET/CT could be used to monitor early cerebral damage, indicating a novel method for evaluating the protective effects of hydrogen on the brain after CA.

TSLP-activated dendritic cells induce an inflammatory T helper type 2 cell response through OX40 ligand.

We recently showed that dendritic cells (DCs) activated by thymic stromal lymphopoietin (TSLP) prime naive CD4(+) T cells to differentiate into T helper type 2 (Th2) cells that produced high amounts of tumor necrosis factor-alpha (TNF-alpha), but no interleukin (IL)-10. Here we report that TSLP induced human DCs to express OX40 ligand (OX40L) but not IL-12. TSLP-induced OX40L on DCs was required for triggering naive CD4(+) T cells to produce IL-4, -5, and -13. We further revealed the following three novel functional properties of OX40L: (a) OX40L selectively promoted TNF-alpha, but inhibited IL-10 production in developing Th2 cells; (b) OX40L lost the ability to polarize Th2 cells in the presence of IL-12; and (c) OX40L exacerbated IL-12-induced Th1 cell inflammation by promoting TNF-alpha, while inhibiting IL-10. We conclude that OX40L on TSLP-activated DCs triggers Th2 cell polarization in the absence of IL-12, and propose that OX40L can switch IL-10-producing regulatory Th cell responses into TNF-alpha-producing inflammatory Th cell responses.

Mast cell and immune inhibitory receptors.

Modulation by balancing activating and inhibitory receptors constitutes an important mechanism for regulating immune responses. Cells that are activated following ligation of receptors bearing immunoreceptor tyrosine-based activation motifs (ITAMs) can be negatively regulated by other receptors bearing immuno-receptor tyrosine-based inhibition motifs (ITIMs). Human mast cells (MCs) are the major effector cells of type I hypersensitivity and important participants in a number of disease processes. Antigen-mediated aggregation of IgE bound to its high-affinity receptor on MCs initiates a complex series of biochemical events leading to MC activation. With great detailed description and analysis of several inhibitory receptors on human MCs, a central paradigm of negative regulation of human MC activation by these receptors has emerged.

Expression of IFNalpha-inducible genes and modulation of HLA-DR and thyroid stimulating hormone receptors in Graves' disease.

Interferon alpha (IFNalpha) plays an important role in the pathogenesis of different autoimmune diseases. IFNalpha is widely used for the treatment of chronic viral infections, particularly chronic hepatitis C virus infection; however, several case reports have emerged describing autoimmune conditions, such as Graves' disease (GD), that have developed in the patients receiving IFNalpha. The mechanism by which IFNalpha is involved in GD remains poorly understood. We investigated the expression of IFNalpha and IFNalpha-inducible genes (IFIGs) in GD and found that IFIGs were overexpressed in 60% of 54 clinical diagnostic GD patients. These elevated IFIGs correlated with serological levels of autoantibody to thyroid stimulating hormone receptor (TSHR). Recombinant human IFNalpha stimulated primary cultured thyrocytes resulted in not only high level expression of IFIGs, but also, more importantly, expression of MHC-II antigens (HLA-DR3 and HLA-DR5) and TSHR in GD subjects. Furthermore, thyroid gland tissues from GD patients over express HLA-DR, TSHR and IFNalpha receptors at both messenger RNA and protein levels. Taken together, these data indicated that in GD patients, IFNalpha can function on thyroid tissue to induce a number of genes, particularly MHC class II molecules which may enhance autoantigen presentation of TSHR on thyrocytes.

Regulation of TLR7/9 responses in plasmacytoid dendritic cells by BST2 and ILT7 receptor interaction.

Plasmacytoid dendritic cells (pDCs) produce copious type I interferon (IFN) upon sensing nucleic acids through Toll-like receptor (TLR) 7 and TLR9. Uncontrolled pDC activation and IFN production are implicated in lymphopenia and autoimmune diseases; therefore, a mechanism controlling pDC IFN production is essential. Human pDCs specifically express an orphan receptor, immunoglobulin-like transcript 7 (ILT7). Here, we discovered an ILT7 ligand expressed by human cell lines and identified it as bone marrow stromal cell antigen 2 (BST2; CD317). BST2 directly binds to purified ILT7 protein, initiates signaling via the ILT7-FcepsilonRIgamma complex, and strongly inhibits production of IFN and proinflammatory cytokines by pDCs. Readily induced by IFN and other proinflammatory cytokines, BST2 may modulate the human pDC's IFN responses through ILT7 in a negative feedback fashion.

Modulation of Notch signaling by antibodies specific for the extracellular negative regulatory region of NOTCH3.

The Notch pathway regulates the development of many tissues and cell types and is involved in a variety of human diseases, making it an attractive potential therapeutic target. This promise has been limited by the absence of potent inhibitors or agonists that are specific for individual human Notch receptors (NOTCH1-4). Using an unbiased functional screening, we identified monoclonal antibodies that specifically inhibit or induce activating proteolytic cleavages in NOTCH3. Remarkably, the most potent inhibitory and activating antibodies bind to overlapping epitopes within a juxtamembrane negative regulatory region that protects NOTCH3 from proteolysis and activation in its resting autoinhibited state. The inhibitory antibodies revert phenotypes conveyed on 293T cells by NOTCH3 signaling, such as increased cellular proliferation, survival, and motility, whereas the activating antibody mimics some of the effects of ligand-induced Notch activation. These findings provide insights into the mechanisms of Notch autoinhibition and activation and pave the way for the further development of specific antibody-based modulators of the Notch receptors, which are likely to be of utility in a wide range of experimental and therapeutic settings.

A new mechanism regulating the initiation of allergic airway inflammation.

BACKGROUND: The earliest immune events induced by allergens are poorly understood, yet are likely essential to understanding how allergic inflammation is established. OBJECTIVE: We sought to describe the earliest signaling events activated by allergen and determine their significance to allergic inflammation. METHODS: A fungal-associated allergenic proteinase (FAP) or ovalbumin was administered once intranasally to wild-type mice to determine their ability to induce allergy-associated genes and initiate allergic lung inflammation. Mice deficient in recombinase activating gene 1, C3a, the C3a anaphylatoxin receptor, and MyD88 were challenged similarly to understand the requirement of these molecules and T and B cells for allergic inflammation. Adoptive T-cell transfer experiments were further performed to determine whether signal transducer and activator of transcription 6 (STAT6) was required for cell recruitment and allergic inflammation. RESULTS: FAP, but not ovalbumin, induced eosinophilic airway inflammation and lung IL-4 production in the absence of adaptive immune cells after the transcriptional induction of allergy-specific airway chemokines. Allergen-mediated chemokine secretion and innate allergic lung inflammation occurred in the absence of STAT6, recombinase activating gene 1, C3a, C3a anaphylatoxin receptor, Toll-like receptor 4, and MyD88 but required intact proteinase activity. Furthermore, FAP induced recruitment of T(H)2 cells and eosinophils to lungs independently of STAT6, which was previously thought to be required for T(H)2 cell homing. CONCLUSION: FAP induces allergic lung inflammation through a previously unrecognized innate immune signaling mechanism. CLINICAL IMPLICATIONS: These findings reveal a new paradigm for understanding how allergic inflammation begins and suggest novel possibilities for the prevention and treatment of allergic diseases, such as asthma.

Maintenance and polarization of human TH2 central memory T cells by thymic stromal lymphopoietin-activated dendritic cells.

The identity of TH2 memory cells and the mechanism regulating their maintenance during allergic inflammation remain elusive. We report that circulated human CD4+ T cells expressing the prostaglandin D2 receptor (CRTH2) are TH2 central memory T cells, characterized by their phenotype, TH2 cytokine production, gene-expression profile, and the ability to respond to allergens. Only dendritic cells (DCs) activated by thymic stromal lymphopoietin (TSLP) can induce a robust expansion of CRTH2+CD4+ TH2 memory cells, while maintaining their central memory phenotype and TH2 commitments. CRTH2+CD4+ TH2 memory cells activated by TSLP-DCs undergo further TH2 polarization and express cystatin A, Charcot-Leydon crystal protein, and prostaglandin D2 synthase, implying their broader roles in allergic inflammation. Infiltrated CRTH2+CD4+ TH2 effector memory T cells in skin lesion of atopic dermatitis were associated with activated DCs, suggesting that TSLP-DCs play important roles not only in TH2 priming, but also in the maintenance and further polarization of TH2 central memory cells in allergic diseases.

Amphiregulin expression in human mast cells and its effect on the primary human lung fibroblasts.

BACKGROUND: Amphiregulin is a member of the epidermal growth factor family and has been shown to stimulate the proliferation of human keratinocytes in an autocrine manner. OBJECTIVE: The aim of the present study was to examine the expression change of growth factors, especially amphiregulin, in human mast cells induced by IgE cross-linking. METHODS: Microarray analysis and RT-PCR were used to analyze the gene expression profile of human cord blood-derived mast cells (CBMCs) stimulated with IgE cross-linking. Protein secretion in the supernatants of CBMCs was measured by means of ELISA. Double-immunofluorescence staining was used to analyze the expression in the lung mast cells. RESULTS: Of the 64 different growth factor genes analyzed, 5 were found to be substantially upregulated. Among them, amphiregulin mRNA was induced by 44-fold in CBMCs on activation through IgE cross-linking. Secretion of amphiregulin protein was evident in CBMCs 8 hours after stimulation. Amphiregulin was also expressed in human lung mast cells from patients with asthma, as demonstrated by means of double-immunofluorescence staining. Amphiregulin promoted the proliferation of the primary human lung fibroblasts, and amphiregulin-treated primary human lung fibroblasts showed a marked increase in the expression of c-fos , a proto-oncogene that facilitates or is required for the proliferation of a wide variety of cells. CONCLUSION: Human CBMCs secreted amphiregulin on IgE cross-linking, and the amphiregulin induced proliferation of primary human lung fibroblasts. These data suggest that local release of amphiregulin by human mast cells could play an important role in lung fibrosis by promoting the proliferation of primary human lung fibroblasts.

Identification and expression of a new type II transmembrane protein in human mast cells.

A cDNA encoding a new type II transmembrane protein has been isolated from human mast cells by subtraction cloning. This cDNA contains an open reading frame of 186 amino acids. RT-PCR analysis showed that this gene is differentially expressed in mast cells. Therefore, the peptide encoded by this gene was termed mast cell-expressed membrane protein 1 (MCEMP1). The MCEMP1 gene contains seven exons and was mapped to human chromosome 19p13.3. The epitope-tagged MCEMP1 has been expressed in mammalian cells and found to be localized to the cellular membrane with its C-terminus extending to the outside of the membrane and N-terminus into the cytoplasmic compartment. Monoclonal antibodies against MCEMP1 were generated and characterized by immunoprecipitation and FACS. The results showed that the native MCEMP1 is expressed in cord blood-derived mast cells and HMC-1 and THP-1 cell lines, but not in other cell types that we have tested. Immunochemical staining of human lung sections showed that MCEMP1 staining is specifically associated with lung mast cells.

The SH3 domain-containing adaptor HIP-55 mediates c-Jun N-terminal kinase activation in T cell receptor signaling.

HIP-55 (hematopoietic progenitor kinase 1 (HPK1)-interacting protein of 55 kDa, also called SH3P7 and mAbp1) is a novel SH3 domain-containing protein. HIP-55 binds to actin filaments both in vitro and in vivo. HIP-55 activates HPK1 and c-Jun N-terminal kinase (JNK), which are two important lymphocyte signaling molecules. Until now, the regulation and function of HIP-55 in T cell receptor (TCR) signaling were unknown. We found that HIP-55 was recruited to glycolipid-enriched microdomains upon TCR stimulation, which indicates that HIP-55 is regulated by TCR signaling. HIP-55 interacted with ZAP-70, a critical protein-tyrosine kinase in TCR signaling, and this interaction was induced by TCR signaling. ZAP-70 phosphorylated HIP-55 at Tyr-334 and Tyr-344 in vitro and in vivo, and the HIP-55 mutant (Y334F/Y344F) was not tyrosine-phosphorylated in stimulated T cells. To study its function in T cell activation, HIP-55-deficient Jurkat T cells were established using the RNA interference approach. In the HIP-55-deficient cells, TCR (but not UV)-stimulated JNK activation was decreased. Furthermore, the activation of HPK1, a known JNK upstream activator and HIP-55-interacting protein, was also decreased in the HIP-55-deficient cells. Our data reveal the regulation of HIP-55 during TCR signaling, and using a genetic approach, we demonstrate for the first time that HIP-55 plays a functional role in TCR signaling.

Calcineurin/nuclear factors of activated T cells (NFAT)-activating and immunoreceptor tyrosine-based activation motif (ITAM)-containing protein (CNAIP), a novel ITAM-containing protein that activates the calcineurin/NFAT-signaling pathway.

We report in this study the identification and characterization of a novel protein that we designated as calcineurin/NFAT-activating and immunoreceptor tyrosine-based activation motif (ITAM)-containing protein (CNAIP). The predicted 270-amino acid sequence contains an N-terminal signal peptide, an immunoglobin domain in the extracellular region, a transmembrane domain and an ITAM in the cytoplasmic tail. Quantitative reverse transcription-PCR showed that CNAIP was preferentially expressed in neutrophils, monocytes, mast cells, and other immune-related cells. Co-transfection of CNAIP expression constructs with luciferase reporter plasmids in HMC-1 cells resulted in activation of interleukin-13 and tumor necrosis factor-alpha promoters, which was mediated through the calcineurin/NFAT-signaling pathway. Mutation of either or both tyrosines in the ITAM abolished transcriptional activation induced by CNAIP, indicating that the ITAM is indispensable for CNAIP function in activating cytokine gene promoters. Thus, it is concluded that CNAIP is a novel ITAM-containing protein that activates the calcineurin/NFAT-signaling pathway and the downstream cytokine gene promoters.

Regulation of activin A expression in mast cells and asthma: its effect on the proliferation of human airway smooth muscle cells.

Activin A, a homodimeric protein (betaAbetaA) and a member of the TGF-beta superfamily, is involved in the inflammatory repair process. Using cDNA microarray analysis, we discovered strong induction of the activin betaA gene in human mast cells (MC) on stimulation with PMA and calcium ionophore (A23187). Activin betaA mRNA was also highly induced in primary cultured murine bone marrow MC (BMMC) after stimulation by IgE receptor cross-linking. Secretion of activin A was evident in human mast cell-1 line cells 3 h after stimulation and progressively increased over time. Activin A was present in the cytoplasm of activated but not unstimulated murine bone marrow MC as demonstrated by immunofluorescence studies, suggesting that secretion of activin A by MC was due to de novo synthesis rather than secretion of preformed protein. Activin A also colocalized with human lung MC from patients with asthma by double-immunofluorescence staining. Furthermore, secretion of activin A was significantly increased in the airway of wild-type mice after OVA sensitization followed by intranasal challenge. Secretion of activin A, however, was greatly reduced in MC-deficient WBB6F(1)-W/W(v) mice as compared with wild-type mice, indicating that MC are an important contributor of activin A in the airways of a murine asthma model. Additionally, activin A promoted the proliferation of human airway smooth muscle cells. Taken together, these data suggest that MC-derived activin A may play an important role in the process of airway remodeling by promoting the proliferation of airway smooth muscle.