Proton Treatment Suppresses Exosome Production in Head and Neck Squamous Cell Carcinoma.

Proton therapy (PT) is emerging as an effective and less toxic alternative to conventional X-ray-based photon therapy (XRT) for patients with advanced head and neck squamous cell carcinomas (HNSCCs) owing to its clustered dose deposition dosimetric characteristics. For optimal efficacy, cancer therapies, including PT, must elicit a robust anti-tumor response by effector and cytotoxic immune cells in the tumor microenvironment (TME). While tumor-derived exosomes contribute to immune cell suppression in the TME, information on the effects of PT on exosomes and anti-tumor immune responses in HNSCC is not known. In this study, we generated primary HNSCC cells from tumors resected from HNSCC patients, irradiated them with 5 Gy PT or XRT, and isolated exosomes from cell culture supernatants. HNSCC cells exposed to PT produced 75% fewer exosomes than XRT- and non-irradiated HNSCC cells. This effect persisted in proton-irradiated cells for up to five days. Furthermore, we observed that exosomes from proton-irradiated cells were identical in morphology and immunosuppressive effects (suppression of IFN-γ release by peripheral blood mononuclear cells) to those of photon-irradiated cells. Our results suggest that PT limits the suppressive effect of exosomes on cancer immune surveillance by reducing the production of exosomes that can inhibit immune cell function.

Targeted knockdown of Kv1.3 channels in T lymphocytes corrects the disease manifestations associated with systemic lupus erythematosus.

Lupus nephritis (LN) is an autoimmune disease with substantial morbidity/mortality and limited efficacy of available therapies. Memory T (Tm) lymphocytes infiltrate LN kidneys, contributing to organ damage. Analysis of LN, diabetic nephropathy, and healthy donor kidney biopsies revealed high infiltration of active CD8+ Tm cells expressing high voltage-dependent Kv1.3 potassium channels-key T cell function regulators-in LN. Nanoparticles that selectively down-regulate Kv1.3 in Tm cells (Kv1.3-NPs) reduced CD40L and interferon-γ (IFNγ) in Tm cells from LN patients in vitro. Kv1.3-NPs were tested in humanized LN mice obtained by engrafting peripheral blood mononuclear cells (PBMCs) from LN patients into immune-deficient mice. LN mice exhibited features of the disease: increased IFNγ and CD3+CD8+ T cell renal infiltration, and reduced survival versus healthy donor PBMC engrafted mice. Kv1.3-NP treatment of patient PBMCs before engraftment decreased CD40L/IFNγ and prolonged survival of LN mice. These data show the potential benefits of targeting Kv1.3 in LN.

Therapeutic Targeting of Follicular T Cells with Chimeric Antigen Receptor-Expressing Natural Killer Cells.

Follicular helper T cells (TFH) are critical for vaccine and infection elicitation of long-lived humoral immunity, but exaggerated TFH responses can promote autoimmunity and other pathologies. It is unfortunate that no clinical interventions exist for the selective depletion of follicular T cells to alleviate these diseases. We engineered a chimeric antigen receptor (CAR) facilitating the specific targeting of cells with high expression levels of human programmed cell death protein 1 (PD-1), a cardinal feature of follicular T cells. CAR-expressing human natural killer (NK) cells robustly and discriminately eliminated PD-1high follicular human T cells in vitro and in a humanized mouse model of lupus-like disease while sparing B cells and other PD-1low T cell subsets, including regulatory T cells. These results establish a strategy for specific targeting of PD-1high T cells that can be advanced as a clinical tool for the selective depletion of pathogenic follicular T cells or other PD-1high target cells in certain disease states.

A Low Neutrophil CD64 Index Is Associated with Sustained Remission During Infliximab Maintenance Therapy.

BACKGROUND: We have previously shown that CD64 surface expression on circulating neutrophils is significantly elevated in children with newly diagnosed Crohn's disease (CD). Our primary aim was to investigate whether elevations in neutrophil CD64 in asymptomatic patients could be used to predict treatment failure during maintenance infliximab. METHODS: Pediatric CD subjects receiving maintenance infliximab in clinical remission (short pediatric CD activity index [shPCDAI] <15) were enrolled. We measured neutrophil CD64 expression (CD64 index, Trillium Diagnostics, LLC) and infliximab trough concentrations. Infliximab failure was defined as an shPCDAI >15 on 2 consecutive infusions, discontinuation of infliximab, hospitalization, endoscopic ulcerations, or surgery during the following year of maintenance infliximab. RESULTS: We enrolled 36 subjects, 22/36 were male and 29/36 were white. Mean (SD) age at study entry was 15 (4) years with a median of 14 (5-20) infusions before study entry. 4/36 were receiving a concurrent immunomodulator. Over 1 year, 15/36 subjects were classified as infliximab failures. Asymptomatic subjects with a neutrophil CD64 index >1 at study entry had a higher probability of treatment failure compared with asymptomatic subjects with a CD64 index <1 (log-rank = 0.002). We found only neutrophil CD64 index >1 and nonwhite race were risk factors for treatment failure by univariate regression analysis. We found no difference in the mean infliximab trough concentration at study entry between treatment failures (2.8 µg/mL, SD, 1.2) and subjects remaining in remission on infliximab (4.2 µg/mL, SD, 3.4; P = 0.17). CONCLUSIONS: Neutrophil CD64 index >1 is a significant risk factor for treatment failure during infliximab maintenance therapy.

Rapid desensitization of mice with anti-FcγRIIb/FcγRIII mAb safely prevents IgG-mediated anaphylaxis.

BACKGROUND: Stimulatory IgG receptors (FcγRs) on bone marrow-derived cells contribute to the pathogenesis of several autoimmune and inflammatory disorders. Monoclonal antibodies that block FcγRs might suppress these diseases, but they can induce anaphylaxis. OBJECTIVE: We wanted to determine whether a rapid desensitization approach can safely suppress IgG/FcγR-mediated anaphylaxis. METHODS: Mice were injected with serially increasing doses of 2.4G2, a rat mAb that blocks the inhibitory FcγR, FcγRIIb, and the stimulatory receptor, FcγRIII. Rectal temperature was used to detect the development of anaphylaxis. Passive and active IgG-mediated anaphylaxis were evaluated in mice that had been rapidly desensitized with 2.4G2 or mock-desensitized in mice in which monocyte/macrophages, basophils, or neutrophils had been depleted or desensitized and in mice in which FcγRI, FcγRIII, and/or FcγRIV had been deleted or blocked. RESULTS: Rapid desensitization with 2.4G2 prevented 2.4G2-induced shock and completely suppressed IgG-mediated anaphylaxis. Rapid desensitization of ovalbumin-sensitized mice with 2.4G2 was safer and more effective than rapid desensitization with ovalbumin. 2.4G2 treatment completely blocked FcγRIII and removed most FcγRI and FcγRIV from nucleated peripheral blood cells. Because IgG(2a)-mediated anaphylaxis was partially FcγRI and FcγRIV dependent, the effects of 2.4G2 on FcγRI and FcγRIV were probably crucial for its complete inhibition of IgG(2a)-mediated anaphylaxis. IgG(2a)-mediated anaphylaxis was partially inhibited by depletion or desensitization of monocyte/macrophages, basophils, or neutrophils. CONCLUSION: IgG-mediated anaphylaxis can be induced by ligation of FcγRI, FcγRIII, or FcγRIV on monocycte/macrophages, basophils, or neutrophils and can be safely suppressed by rapid desensitization with anti-FcγRII/RIII mAb. A similar approach may safely suppress other FcγR-dependent immunopathology.

Induction and suppression of allergic diarrhea and systemic anaphylaxis in a murine model of food allergy.

BACKGROUND: The clinical manifestations of food allergy include diarrhea and systemic anaphylaxis (shock), which can occur together or by themselves in different subjects. Although ingested food antigens need to be absorbed to induce shock, it is not known whether they need to be absorbed to induce diarrhea. OBJECTIVE: We sought to identify mechanisms that determine whether food allergy induces diarrhea versus shock and determine whether diarrhea requires absorption of ingested antigens. METHODS: These issues were studied in mice in active, passive, and hybrid immunization models. The active model was used to determine the allergic diarrhea susceptibility of J chain- and polymeric immunoglobulin receptor-deficient mice, which are unable to secrete IgA. The hybrid model was used to determine whether intravenously administered antigen-specific IgG antibody, which is not secreted into the gut, can protect against allergic diarrhea, as well as shock. RESULTS: Shock, but not diarrhea, was induced in naive mice by using intravenous IgE anti-trinitrophenyl (TNP) antibody, followed by oral TNP-BSA, whereas both were induced in mice presensitized with intraperitoneal ovalbumin/alum plus oral ovalbumin. More TNP-BSA was required to induce shock than diarrhea in presensitized mice, and intravenous IgG anti-TNP antibody, which is not secreted into the gut, protected these mice against both diarrhea and shock. Consistent with this, chicken ovalbumin-immunized J chain- and polymeric immunoglobulin receptor-deficient mice, which have high serum IgA levels but little intestinal IgA, resisted diarrhea induction. CONCLUSION: Intestinal immunity and oral antigen dose determine whether diarrhea, systemic anaphylaxis, or both are induced, and ingested antigen must be absorbed to induce either response.

MHC class I-specific antibody binding to nonhematopoietic cells drives complement activation to induce transfusion-related acute lung injury in mice.

Transfusion-related acute lung injury (TRALI), a form of noncardiogenic pulmonary edema that develops during or within 6 h after a blood transfusion, is the most frequent cause of transfusion-associated death in the United States. Because development of TRALI is associated with donor antibodies (Abs) reactive with recipient major histocompatibility complex (MHC), a mouse model has been studied in which TRALI-like disease is caused by injecting mice with anti-MHC class I monoclonal Ab (mAb). Previous publications with this model have concluded that disease is caused by FcR-dependent activation of neutrophils and platelets, with production of reactive oxygen species that damage pulmonary vascular endothelium. In this study, we confirm the role of reactive oxygen species in the pathogenesis of this mouse model of TRALI and show ultrastructural evidence of pulmonary vascular injury within 5 min of anti-MHC class I mAb injection. However, we demonstrate that disease induction in this model involves macrophages rather than neutrophils or platelets, activation of complement and production of C5a rather than activation of FcγRI, FcγRIII, or FcγRIV, and binding of anti-MHC class I mAb to non-BM-derived cells such as pulmonary vascular endothelium. These observations have important implications for the prevention and treatment of TRALI.

Ingested allergens must be absorbed systemically to induce systemic anaphylaxis.

BACKGROUND: IgE-mediated food allergy is a common cause of enteric disease and is responsible for approximately 100 systemic anaphylaxis deaths in the United States each year. IgG antibodies can protect against IgE-mediated systemic anaphylaxis induced by injected antigens by neutralizing antigens before they can bind to mast cell-associated IgE. OBJECTIVE: We have investigated whether IgA and IgG antibodies can similarly protect against systemic, IgE-mediated anaphylaxis induced by ingested antigens and, if so, whether IgA and IgG antibodies protect by neutralizing antigens before or after their systemic absorption. METHODS: Murine passive and active anaphylaxis models were used to study the abilities of serum versus gut lumenal IgA antibodies and serum IgG antibodies to inhibit systemic anaphylaxis induced by ingested allergens in normal mice, mice deficient in the ability to secrete IgA into the intestines, and mice in which intestinal IL-9 overexpression has induced intestinal mastocytosis and increased intestinal permeability. RESULTS: IgE-mediated systemic anaphylaxis and mast cell degranulation induced by antigen ingestion are suppressed by both serum antigen-specific IgA and IgG, but not by IgA within the gut lumen. CONCLUSION: Systemic rather than enteric antibodies protect against systemic anaphylaxis induced by ingested antigen. This implies that ingested antigens must be absorbed systemically to induce anaphylaxis and suggests that immunization protocols that increase serum levels of antigen-specific, non-IgE antibodies should protect against severe food allergy.

Intestinal epithelial cell secretion of RELM-beta protects against gastrointestinal worm infection.

Th2 cells drive protective immunity against most parasitic helminths, but few mechanisms have been demonstrated that facilitate pathogen clearance. We show that IL-4 and IL-13 protect against intestinal lumen-dwelling worms primarily by inducing intestinal epithelial cells (IECs) to differentiate into goblet cells that secrete resistin-like molecule (RELM) beta. RELM-beta is essential for normal spontaneous expulsion and IL-4-induced expulsion of Nippostrongylus brasiliensis and Heligmosomoides polygyrus, which both live in the intestinal lumen, but it does not contribute to immunity against Trichinella spiralis, which lives within IEC. RELM-beta is nontoxic for H. polygyrus in vitro but directly inhibits the ability of worms to feed on host tissues during infection. This decreases H. polygyrus adenosine triphosphate content and fecundity. Importantly, RELM-beta-driven immunity does not require T or B cells, alternative macrophage activation, or increased gut permeability. Thus, we demonstrate a novel mechanism for host protection at the mucosal interface that explains how stimulation of epithelial cells by IL-4 and IL-13 contributes to protection against parasitic helminthes that dwell in the intestinal lumen.

Nonredundant roles for B cell-derived IL-10 in immune counter-regulation.

IL-10 plays a central role in restraining the vigor of inflammatory responses, but the critical cellular sources of this counter-regulatory cytokine remain speculative in many disease models. Using a novel IL-10 transcriptional reporter mouse, we found an unexpected predominance of B cells (including plasma cells) among IL-10-expressing cells in peripheral lymphoid tissues at baseline and during diverse models of in vivo immunological challenge. Use of a novel B cell-specific IL-10 knockout mouse revealed that B cell-derived IL-10 nonredundantly decreases virus-specific CD8(+) T cell responses and plasma cell expansion during murine cytomegalovirus infection and modestly restrains immune activation after challenge with foreign Abs to IgD. In contrast, no role for B cell-derived IL-10 was evident during endotoxemia; however, although B cells dominated lymphoid tissue IL-10 production in this model, myeloid cells were dominant in blood and liver. These data suggest that B cells are an underappreciated source of counter-regulatory IL-10 production in lymphoid tissues, provide a clear rationale for testing the biological role of B cell-derived IL-10 in infectious and inflammatory disease, and underscore the utility of cell type-specific knockouts for mechanistic limning of immune counter-regulation.

Peanuts can contribute to anaphylactic shock by activating complement.

BACKGROUND: Peanut allergy is the most common food-related cause of lethal anaphylaxis and, unlike other food allergies, typically persists into adulthood. Resistance to digestion and dendritic cell activation by the major peanut allergen Ara h 1 are reported to contribute to its allergenicity. OBJECTIVE: We sought to evaluate whether peanut molecules might also promote anaphylaxis through an innate immune mechanism. METHODS: Naive mice were treated with a beta-adrenergic receptor antagonist and long-acting IL-4 to increase sensitivity to vasoactive mediators and injected with peanut extract (PE). Shock was detected and quantified by means of rectal thermometry. Gene-deficient mice and specific antagonists were used to determine the roles of specific cell types, complement, Fc receptors, and vasoactive mediators in shock pathogenesis. RESULTS: PE induces dose-dependent shock. PE activates complement in vivo in mice and in vitro in mice and human subjects. C3a and, to a lesser extent, stimulatory immunoglobulin receptors contribute to PE-induced shock. PE-induced shock depends more on macrophages and basophils than on mast cells. Platelet-activating factor and, to a lesser extent, histamine contribute to PE-induced shock. PE induces shock in the absence of the adaptive immune system. LPS contamination is not responsible for PE-induced shock. PE and IgE-mediated mast cell degranulation synergistically induce shock. Tree nuts have similar effects to PE, and skim milk and egg white do not. CONCLUSION: Peanuts can contribute to shock by causing production of C3a, which stimulates macrophages, basophils, and mast cells to produce platelet-activating factor and histamine.

CD48 is an allergen and IL-3-induced activation molecule on eosinophils.

Eosinophils are involved in a variety of allergic, parasitic, malignant, and idiopathic disorders by releasing a variety of factors including specific granule proteins, lipid mediators, and proinflammatory and immunoregulatory cytokines and chemokines. In addition, they interact with various cell types in the inflamed tissue. Yet, the mechanism of eosinophil activation is still poorly understood. Recently, we described the expression and function of the CD2-subfamily of receptors and especially 2B4 on human eosinophils. In this study we focus on CD48, the high-affinity ligand of 2B4. CD48 is a GPI-anchored protein involved in cellular activation, costimulation, and adhesion, but has not been studied on eosinophils. We demonstrate that human eosinophils from atopic asthmatics display enhanced levels of CD48 expression and that IL-3 up-regulates CD48 expression. Furthermore, cross-linking CD48 on human eosinophils triggers release of eosinophil granule proteins. Assessment of CD48 expression in a murine model of experimental asthma revealed that CD48 is induced by allergen challenge and partially regulated by IL-3. Additionally, anti-IL-3 reduces CD48 expression and the degree of airway inflammation. Thus, CD48 is an IL-3-induced activating receptor on eosinophils, likely involved in promoting allergic inflammation.

Distinct and collaborative roles of Drosophila EXT family proteins in morphogen signalling and gradient formation.

Heparan sulfate proteoglycans (HSPG) have been implicated in regulating the signalling activities of secreted morphogen molecules including Wingless (Wg), Hedgehog (Hh) and Decapentaplegic (Dpp). HSPG consists of a protein core to which heparan sulfate (HS) glycosaminoglycan (GAG) chains are attached. The formation of HS GAG chains is catalyzed by glycosyltransferases encoded by members of the EXT family of putative tumor suppressors linked to hereditary multiple exostoses. Previous studies in Drosophila demonstrated that tout-velu (ttv), the Drosophila EXT1, is required for Hh movement. However, the functions of other EXT family members are unknown. We have identified and isolated the other two members of the Drosophila EXT family genes, which are named sister of tout-velu (sotv) and brother of tout-velu (botv), and encode Drosophila homologues of vertebrate EXT2 and EXT-like 3 (EXTL3), respectively. We show that both Hh and Dpp signalling activities, as well as their morphogen distributions, are defective in cells mutant for ttv, sotv or botv in the wing disc. Surprisingly, although Wg morphogen distribution is abnormal in ttv, sotv and botv, Wg signalling is only defective in botv mutants or ttv-sotv double mutants, and not in ttv nor sotv alone, suggesting that Ttv and Sotv are redundant in Wg signalling. We demonstrate further that Ttv and Sotv form a complex and are co-localized in vivo. Our results, along with previous studies on Ttv, provide evidence that all three Drosophila EXT proteins are required for the biosynthesis of HSPGs, and for the gradient formation of the Wg, Hh and Dpp morphogens. Our results also suggest that HSPGs have two distinct roles in Wg morphogen distribution and signalling.