The CD40 gene, an important immune regulatory gene, is also expressed and functional on non-myeloid derived cells, many of which are targets for tissue specific autoimmune diseases, including beta cells in type 1 diabetes, intestinal epithelial cells in Crohn’s disease, and thyroid follicular cells in Graves’ disease (GD). Whether target tissue CD40 expression plays a role in autoimmune disease etiology has yet to be determined. Here we show, that target-tissue over-expression of CD40 plays a key role in the etiology of autoimmunity. Using a murine model of GD, we demonstrated that thyroidal CD40 over-expression augmented the production of thyroid specific antibodies, resulting in more severe experimental autoimmune Graves’ disease (EAGD), whereas deletion of thyroidal CD40 suppressed disease. Using transcriptome and immune-pathway analyses we showed that in both EAGD mouse thyroids and human primary thyrocytes, CD40 mediates this effect by activating downstream cytokines and chemokines, most notably IL-6. To translate these findings into therapy, we blocked IL-6 during EAGD induction in the setting of thyroidal CD40 over-expression, and showed decreased levels of TSHR stimulating antibodies and frequency of disease. We conclude that target tissue over-expression of CD40 plays a key role in the etiology of organ specific autoimmune disease.
Eosinophilic esophagitis (EE) is an emerging disease associated with both food and respiratory allergy characterized by extensive esophageal tissue remodeling and abnormal esophageal gene expression including increased IL-13. We investigated the ability of increased airway IL-13 to induce EE-like changes. Mice that overexpress an IL-13 transgene in the lung (but not esophagus) accumulated esophageal IL-13 and developed prominent esophageal remodeling with epithelial hyperplasia, angiogenesis, collagen deposition and increased circumference. IL-13-induced marked changes in esophageal transcripts overlapped with the human EE esophageal transcriptome. IL-13-induced esophageal eosinophilia was eotaxin-1 (but not eotaxin-2) dependent but remodeling occurred independent of eosinophils, as demonstrated by studying eosinophil lineage-deficient IL-13 transgenic mice. IL-13-induced remodeling was significantly enhanced by IL-13Rα2 gene deletion, indicating an inhibitory effect of IL-13Rα2. In the murine system, there was partial overlap between IL-13-induced genes in the lung and esophagus, yet the transcriptomes were also divergent at the tissue level. In human esophagus, IL-13 levels correlated with the magnitude of the EE transcriptome. In conclusion, inducible airway expression of IL-13 results in an esophageal gene expression and extensive tissue remodeling pattern that resembles human EE. Notably, we have identified a pathway for inducing EE-like changes that is IL-13-driven, eosinophil-independent and suppressed by IL-13Rα2.
The clinical manifestations of food allergy include diarrhea and systemic anaphylaxis (shock), which can occur together or by themselves in different individuals. Although ingested food antigens need to be absorbed to induce shock, it is not known whether they need to be absorbed to induce diarrhea.
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 pIgR-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.
Shock, but not diarrhea was induced in naïve mice by intravenous IgE anti-TNP antibody, followed by oral TNP-bovine serum albumin, whereas both were induced in mice presensitized with intraperitoneal ovalbumin/alum plus oral ovalbumin. More TNP-bovine serum albumin 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, OVA-immunized J chain- and pIgR-deficient mice, which have high serum IgA but little intestinal IgA, resisted diarrhea induction.
Intestinal immunity and oral Ag dose determine whether diarrhea and/or systemic anaphylaxis are induced and ingested Ag must be absorbed to induce either response.
IgA; IgE; IgG; J chain; polymeric Ig receptor
Resistin-like molecule α (Relm-α) is one of the most up-regulated gene products in allergen- and parasite-associated Th2 responses. Localized to alternatively activated macrophages, Relm-α was shown to exert an anti-inflammatory effect in parasite-induced Th2 responses, but its role in experimental asthma remains unexplored. Here, we analyzed the cellular source, the IL-4 receptors required to stimulate Relm-α production, and the role of Relm-α after experimental asthma induction by IL-4, IL-13, or multiple experimental regimes, including ovalbumin and Aspergillus fumigatus immunization. We demonstrate that Relm-α was secreted into the airway lumen, dependent on both the IL-13 receptor–α1 chain and likely the Type I IL-4 receptor, and differentially localized to epithelial cells and myeloid cells, depending on the specific cytokine or aeroallergen trigger. Studies performed with Retnla gene–targeted mice demonstrate that Relm-α was largely redundant in terms of inducing the infiltration of Th2 cytokines, mucus, and inflammatory cells into the lung. These results mirror the dispensable role that other alternatively activated macrophage products (such as arginase 1) have in allergen-induced experimental asthma and contrast with their role in the setting of parasitic infections. Taken together, our findings demonstrate the distinct utilization of IL-4/IL-13 receptors for the induction of Relm-α in the lungs. The differential regulation of Relm-α expression is likely determined by the relative expression levels of IL-4, IL-13, and their corresponding receptors, which are differentially expressed by divergent cells (i.e., epithelial cells and macrophages.) Finally, we identify a largely redundant functional role for Relm-α in acute experimental models of allergen-associated Th2 immune responses.
resistin-like molecule–α; asthma; IL-4; IL-13Rα1
Anaphylaxis is a rapid, life-threatening hypersensitivity reaction. Until recently, it was mainly attributed to histamine released by mast cells activated by allergen crosslinking (XL) of FcεRI-bound allergen-specific IgE. However, recent reports established that anaphylaxis could also be triggered by basophil, macrophage and neutrophil secretion of platelet activating factor subsequent to FcγR stimulation by IgG/Ag complexes. We have investigated the contribution of Fyn and Lyn tyrosine kinases to FcγRIIb and FcγRIII signaling in the context of IgG-mediated passive systemic anaphylaxis (PSA). We found that mast cell IgG XL induced Fyn, Lyn, Akt, Erk, p38 and JNK phosphorylation. Additionally, IgG XL of mast cells, basophils and macrophages resulted in Fyn- and Lyn-regulated mediator release in vitro. FcγR–mediated activation was enhanced in Lyn-deficient (KO) cells, but decreased in Fyn KO cells, compared to wild type cells. More importantly, Lyn KO mice displayed significantly exacerbated PSA features while no change was observed for Fyn KO mice, compared to wild type littermates. Intriguingly, we establish that mast cells account for the majority of serum histamine in IgG-induced PSA. Taken together, our findings establish pivotal roles for Fyn and Lyn in the regulation of PSA and highlight their unsuspected functions in IgG-mediated pathologies.
Mechanistic understanding of RP105 has been confounded by the fact that this TLR homolog has appeared to have opposing, cell type-specific effects on TLR4 signaling. While RP105 inhibits TLR4-driven signaling in cell lines and myeloid cells, impaired LPS-driven proliferation by B cells from RP105−/− mice has suggested that RP105 facilitates TLR4 signaling in B cells. We show here that modulation of B cell proliferation by RP105 is not a function of B cell-intrinsic expression of RP105, and identify a mechanistic role for dysregulated BAFF expression in the proliferative abnormalities of B cells from RP105−/− mice: serum BAFF levels are elevated in RP105−/− mice, and partial BAFF neutralization rescues aberrant B cell proliferative responses in such mice. These data indicate that RP105 does not have dichotomous effects on TLR4 signaling, and emphasize the need for caution in interpreting the results of global genetic deletion.
The repair protein trefoil factor 2 promotes Th2 responses to helminth infection and allergens in part by inducing IL-33.
The molecular mechanisms that drive mucosal T helper type 2 (TH2) responses against parasitic helminths and allergens remain unclear. In this study, we demonstrate in mice that TFF2 (trefoil factor 2), an epithelial cell–derived repair molecule, is needed for the control of lung injury caused by the hookworm parasite Nippostrongylus brasiliensis and for type 2 immunity after infection. TFF2 is also necessary for the rapid production of IL-33, a TH2-promoting cytokine, by lung epithelia, alveolar macrophages, and inflammatory dendritic cells in infected mice. TFF2 also increases the severity of allergic lung disease caused by house dust mite antigens or IL-13. Moreover, TFF2 messenger RNA expression is significantly increased in nasal mucosal brushings during asthma exacerbations in children. These experiments extend the biological functions of TFF2 from tissue repair to the initiation and maintenance of mucosal TH2 responses.
In a manner partially independent of activating Fcγ receptors, antibody-mediated production of complement component C5a and recruitment of macrophages elicit 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.
Genome-wide screening and positional cloning have linked neuropeptide S receptor 1 (NPSR1) with asthma and airway hyperresponsiveness. However, the mechanism by which NPSR1 regulates pulmonary responses remains elusive. Because neuropeptide S and its receptor NPSR1 are expressed in brain regions that regulate respiratory rhythm, and Npsr1-deficient mice have impaired stress and anxiety responses, we aimed to investigate whether neuropeptide S and NPSR1 regulate respiratory function through a central-mediated pathway. After neuropeptide S intracerebroventricular administration, respiratory responses of wildtype and Npsr1-deficient mice were monitored by whole-body or invasive plethysmography with or without serial methacholine inhalation. Airway inflammatory and hyperresponsiveness were assessed in allergen-challenged (ovalbumin or Aspergillus fumigatus) Npsr1-deficient mice. Analysis of breathing patterns by whole-body plethysmography revealed that intracerebroventricular neuropeptide S, as compared with the artificial cerebral spinal fluid control, increased respiratory frequency and decreased tidal volume in an NPSR1-dependent manner but did not affect enhanced pause. Following serial methacholine inhalation, intracerebroventricular neuropeptide S increased respiratory frequency in wildtype mice, but not Npsr1-deficient mice, and had no effect on tidal volume. Intracerebroventricular neuropeptide S significantly reduced airway responsiveness to methacholine as measured by whole-body plethysmography. Npsr1 deletion had no impact on airway inflammation or hyperresponsiveness in ovalbumin- or Aspergillus fumigatus-induced experimental asthma. Our results demonstrate that neuropeptide S and NPSR1 regulate respiratory function through a central nervous system-mediated pathway.
Respiration; brain; neuropeptide S; neuropeptide S receptor 1; panting; stress
IgE-mediated food allergy is a common cause of enteric disease and is responsible for approximately 100 systemic anaphylaxis deaths in the USA 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.
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.
Murine passive and active anaphylaxis models were used to study the abilities of serum vs. 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.
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.
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.
Induction of a systemic IgG or IgA antibody response against a food allergen should protect against induction of systemic anaphylaxis by ingestion of that allergen.
Mouse; food allergy; IgE; IgA; IgG; allergic diarrhea; blocking antibodies
A defining feature of inflammation is the accumulation of innate immune cells in the tissue that are thought to be recruited from the blood. We reveal that a distinct process exists in which tissue macrophages undergo rapid in situ proliferation in order to increase population density. This inflammatory mechanism occurred during T helper 2 (Th2)-related pathologies under the control of the archetypal Th2 cytokine interleukin-4 (IL-4), and was a fundamental component of Th2 inflammation because exogenous IL-4 was sufficient to drive accumulation of tissue macrophages through self-renewal. Thus, expansion of innate cells necessary for pathogen control or wound repair can occur without recruitment of potentially tissue-destructive inflammatory cells.
Peanuts are a frequent cause of food allergy and the most common cause of fatal food-induced anaphylaxis in the U.S. Advances during the past two years have promoted our understanding of peanut allergens and peanut allergy prevalence, etiology, diagnosis and therapy. The advances highlighted in this review include evidence that the peanut allergens most important in disease differ in different parts of the world, that early oral exposure to peanuts may decrease the frequency of peanut allergy, while early non-oral exposure may have the opposite effect, that complement activation by peanut constituents appears to promote peanut-induced anaphylaxis and that oral immunotherapy, anti-IgE antibody and an herbal formulation are promising approaches for treatment of this disorder.
IL-4Rα expression on airway smooth muscle cells is sufficient for the development of airway hyperresponsiveness.
Production of the cytokines IL-4 and IL-13 is increased in both human asthma and mouse asthma models, and Stat6 activation by the common IL-4/IL-13R drives most mouse model pathophysiology, including airway hyperresponsiveness (AHR). However, the precise cellular mechanisms through which IL-4Rα induces AHR remain unclear. Overzealous bronchial smooth muscle constriction is thought to underlie AHR in human asthma, but the smooth muscle contribution to AHR has never been directly assessed. Furthermore, differences in mouse versus human airway anatomy and observations that selective IL-13 stimulation of Stat6 in airway epithelium induces murine AHR raise questions about the importance of direct IL-4R effects on smooth muscle in murine asthma models and the relevance of these models to human asthma. Using transgenic mice in which smooth muscle is the only cell type that expresses or fails to express IL-4Rα, we demonstrate that direct smooth muscle activation by IL-4, IL-13, or allergen is sufficient but not necessary to induce AHR. Five genes known to promote smooth muscle migration, proliferation, and contractility are activated by IL-13 in smooth muscle in vivo. These observations demonstrate that IL-4Rα promotes AHR through multiple mechanisms and provide a model for testing smooth muscle–directed asthma therapeutics.
During an immune response, most effector T cells die, while some are maintained and become memory T cells. Factors controlling the survival of effector CD4+ and CD8+ T cells remain unclear. Here, we assessed the role of IL-7, IL-15, and their common signal transducer, STAT5, in maintaining effector CD4+ and CD8+ T cell responses. Following viral infection, IL-15 was required to maintain a subpopulation of effector CD8+ T cells expressing high levels of killer cell lectin-like receptor subfamily G, member 1 (KLRG1) and lower levels of CD127, while IL-7 and IL-15 acted together to maintain KLRG1loCD127hi CD8+ effector T cells. In contrast, effector CD4+ T cell numbers were not affected by the individual or combined loss of IL-15 and IL-7. Both IL-7 and IL-15 drove phosphorylation of STAT5 (pSTAT5) within effector CD4+ and CD8+ T cells. When STAT5 was deleted during the course of infection, both KLRG1hiCD127lo and KLRG1loCD127hi CD8+ T cells were lost, while effector CD4+ T cell populations were maintained. Further, STAT5 was required to maintain expression of Bcl-2 in effector CD8+, but not CD4+, T cells. Finally, IL-7 and IL-15 required STAT5 to induce Bcl-2 expression and to maintain effector CD8+ T cells. Together, these data demonstrate that IL-7 and IL-15 signaling converge on STAT5 to maintain effector CD8+ T cell responses.
In C57BL/6 mice, the recruitment of mast cell progenitors (MCps) to the lung is a feature of Ag-induced pulmonary inflammation that requires sensitization and challenge and is totally inhibited by the administration of anti-CD4 at the time of challenge. When mAb to TGFβ1 or to IL-10R was administered at the time of challenge, the recruitment of MCp/106 mononuclear cells (MNCs) to the lung was inhibited by 56.3 and 69.6%, respectively, whereas mAb to IL-4, IFN-γ, IL-6, IL-17A, and IL-17F had no effect. In sensitized and challenged C57BL/6 mice lacking TGFβRII on CD4+ cells, the recruitment of MCp/106 MNCs was reduced by 67.8%. The requirement for TGFβ1 and IL-10 suggested a role for CD4+CD25+ T regulatory cells. Mice treated with anti-CD25 at the time of Ag-challenge showed a reduction in the recruitment of MCp/106 MNCs by 77.2% without any reduction in MNC influx. These results reveal an unexpected role for T regulatory cells in promoting the recruitment of MCps to the lungs of C57BL/6 mice with Ag-induced pulmonary inflammation.
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 non-redundantly decreases virus-specific CD8+ T cell responses and plasma cell expansion during murine cytomegalovirus (MCMV4) infection and modestly restrains immune activation after challenge with foreign antibodies to IgD. In contrast, no role for B cell-derived IL-10 was evident during endotoxemia; however, while 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 under-appreciated 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.
B cells; cytokines; gene regulation; inflammation; transgenic/knockout mice
The cytokines IL-10 and TGF-β regulate immunity and inflammation. IL-10 is known to suppress the extent of hepatic damage caused by parasite ova during natural infection with Schistosoma mansoni, but the role of TGF-β is less clear. Cytokine blockade studies in mice revealed that anti-IL-10R mAb treatment during acute infection modestly increased cytokine production and liver damage, whereas selective anti-TGF-β mAb treatment had marginal effects. In contrast, mice administered both mAbs developed severe hepatic inflammation, with enlarged, necrotic liver granulomas, cachexia, and >80% mortality by 8 wk postinfection, despite increased numbers of CD4+CD25+Foxp3+ T regulatory cells. Blocking both IL-10 and TGF-β at the onset of egg production also significantly increased IL-4, IL-6, TNF, IFN-γ, and IL-17 production and markedly increased hepatic, peritoneal, and splenic neutrophilia. In contrast, coadministration of anti-IL-10R and TGF-β mAbs had little effect upon parasite ova-induced intestinal pathology or development of alternatively activated macrophages, which are required to suppress intestinal pathology. This suggests that inflammation is controlled during acute S. mansoni infection by two distinct, organ-specific mechanisms: TGF-β and IL-10 redundantly suppress hepatic inflammation while intestinal inflammation is regulated by alternatively activated macrophages.
Alternatively activated macrophages prevent lethal intestinal pathology caused by worm ova in mice infected with the human parasite Schistosoma mansoni through mechanisms that are currently unclear. This study demonstrates that arginase I (Arg I), a major product of IL-4– and IL-13–induced alternatively activated macrophages, prevents cachexia, neutrophilia, and endotoxemia during acute schistosomiasis. Specifically, Arg I-positive macrophages promote TGF-β production and Foxp3 expression, suppress Ag-specific T cell proliferation, and limit Th17 differentiation. S. mansoni-infected Arg I-deficient bone marrow chimeras develop a marked accumulation of worm ova within the ileum but impaired fecal egg excretion compared with infected wild-type bone marrow chimeras. Worm ova accumulation in the intestines of Arg I-deficient bone marrow chimeras was associated with intestinal hemorrhage and production of molecules associated with classical macrophage activation (increased production of IL-6, NO, and IL-12/IL-23p40), but whereas inhibition of NO synthase-2 has marginal effects, IL-12/IL-23p40 neutralization abrogates both cachexia and intestinal inflammation and reduces the number of ova within the gut. Thus, macrophage-derived Arg I protects hosts against excessive tissue injury caused by worm eggs during acute schistosomiasis by suppressing IL-12/IL-23p40 production and maintaining the Treg/Th17 balance within the intestinal mucosa.
IL 4 receptor α (IL-4Rα) expression by non-bone marrow (BM)-derived cells is required to protect hosts against several parasitic helminth species. In contrast, we demonstrate that IL-4Rα expression by BM-derived cells is both necessary and sufficient to prevent Schistosoma mansoni-infected mice from developing severe inflammation directed against parasite ova, whereas IL-4Rα expression by non-BM-derived cells is neither necessary nor sufficient. Chimeras that express IL-4Rα only on non-BM-derived cells still produce Th2 cytokines, but overproduce IL-12p40, TNF, and IFN-γ, fail to generate alternatively activated macrophages, and develop endotoxemia and severe hepatic and intestinal pathology. In contrast, chimeras that express IL-4Rα only on BM-derived cells have extended survival, even though the granulomas that they develop around parasite eggs are small and devoid of collagen. These observations identify distinct roles for IL-4/IL-13 responsive cell lineages during schistosomiasis: IL-4Rα-mediated signaling in non-BM-derived cells regulates granuloma size and fibrosis, whereas signaling in BM-derived cells suppresses parasite egg-driven inflammation within the liver and intestine.
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) β. RELM-β 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-β 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-β–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.
Allergic asthma results from inappropriate Th2-mediated inflammation. Both IL-4 and IL-13 contribute to asthma pathogenesis, but IL-4 predominantly drives Th2 induction, while IL-13 is necessary and sufficient for allergen-induced AHR and goblet cell hyperplasia. Although these 2 cytokines share signaling components, the molecular mechanisms by which they mediate different phases of the allergic asthma response remain elusive.
We sought to clarify the role(s) of IL-4 and IL-13 in asthma pathogenesis.
We employed DNA Affymetrix microarrays to profile pulmonary gene expression in BALB/c mice inoculated intratracheally with ragweed pollen (RWP), house dust mite (HDM), IL-4, IL-13, or both cytokines. IL-13 dependence was confirmed by comparing pulmonary gene expression in HDM-inoculated WT and IL-13KO mice.
A signature gene expression profile consisting of 23 genes was commonly induced by inoculation with HDM, RWP, or IL-4 plus IL-13. Although rIL-4 and rIL-13 treatment induced an overlapping set of genes, IL-4 uniquely induced 21 genes, half of which were IFN response genes and half were genes important in immunoregulation. IL-13 uniquely induced 8 genes, most of which encode proteins produced by epithelial cells.
IL-4 and IL-13 together account for most allergen-induced pulmonary genes. Selective IL-4 induction of IFN-γ-response genes and other genes that may negatively regulate allergic inflammation may partially explain the greater importance of IL-13 in the effector phase of allergic airway disease.
The identification of genes selectively induced by individual cytokines, especially IL-13, may provide novel therapeutic targets for the treatment of asthma.
Th2 cytokines; microarrays; allergic asthma; mouse
Although mice have ng/ml serum levels of soluble (s) IL-13Rα2, humans lack sIL-13Rα2 in serum. Our data provide a mechanism for this biologic divergence. In mice, discrete transcripts encoding s and membrane (mem) forms of IL-13Rα2 are generated by alternative splicing. We utilized siRNA to specifically deplete the transcript encoding memIL-13Rα2 (full-length) or sIL-13Rα2 (ΔEx10) in murine cells. Depletion of the full-length transcript decreased memIL-13Rα2, but had no effect on the level of sIL-13Rα2 in cell supernatants at baseline or following cytokine stimulation. Depletion of the ΔEx10 transcript decreased sIL-13Rα2 in supernatants at baseline and following stimulation. In contrast to mice, we were unable to find a transcript encoding sIL-13Rα2 in humans and siRNA-mediated depletion of full-length IL-13Rα2 decreased both sIL-13Rα2 and memIL-13Rα2 in human cells. Inhibition of matrix metalloproteinases (MMPs)/MMP-8 abolished production of sIL-13Rα2 from human cells. Thus, sIL-13Rα2 is derived exclusively from the memIL-13Rα2 transcript in humans through MMPs/MMP-8 cleavage of memIL-13Rα2, supporting a limited role for sIL-13Rα2 in humans and highlighting the potential importance of memIL-13Rα2 in human immunity. These observations require consideration when results of murine IL-13 studies are applied to humans.
IL-13 receptor; membrane form; soluble form; siRNA; IL-13; MMP-8
T cell proliferation and survival are regulated by the cytokine receptor common γ chain (γc)3-associated cytokines IL-2, IL-7 and IL-15 while IL-4, another γc-associated cytokine, is thought to primarily affect T cell quality rather than quantity. In contrast, our experiments reveal that endogenously produced IL-4 is a direct, non-redundant and potent stimulator of CD8+ T cell proliferation in antigen- and pathogen-induced CD8+ T cell responses. These stimulatory effects of IL-4 are observed in both BALB/c and C57BL/6 mice and activate both naïve and memory/activated phenotype CD8+ T cells, although the former are stimulated less than the latter. IL-4 effects are IL-7- and IL-15-independent, but MHC class I-dependent stimulation appears to be required for the mitogenic effect of IL-4 on naïve phenotype CD8+ T cells. Thus, endogenously produced IL-4 is an important regulator of quantitative as well as qualitative aspects of T cell immunity.
Rodent; T Cells; Cell Proliferation; Cytokine Receptors; Cytokines
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 h1, are reported to contribute to its allergenicity.
Evaluate whether peanut molecules may also promote anaphylaxis through an innate immune mechanism.
Naïve mice were treated with a β-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 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.
1) PE induces dose-dependent shock; 2) PE activates complement in vivo in mice and in vitro in mice and humans; 3) C3a, and, to a lesser extent, stimulatory immunoglobulin (Ig) receptors contribute to PE-induced shock; 4) PE-induced shock depends more on macrophages and basophils than on mast cells; 5) platelet activating factor and, to a lesser extent, histamine contribute to PE-induced shock; 6) PE induces shock in the absence of the adaptive immune system; 7) LPS contamination is not responsible for PE-induced shock; 8) PE and IgE-mediated mast cell degranulation synergistically induce shock; and 9) Tree nuts have similar effects to PE; skim milk and egg white do not.
Peanuts can contribute to shock by causing production of C3a, which stimulates macrophages, basophils and mast cells to produce PAF and histamine.
peanut; C3a; complement; anaphylaxis; shock; macrophages; mast cells; basophils; PAF; histamine
Pulmonary mast cell progenitor (MCp) numbers increase dramatically in sensitized and aerosolized Ag-challenged mice. This increase depends on CD4+ T cells, as no MCp increase occurs in the lungs of sensitized wild-type (WT) mice after mAb depletion of CD4+ but not CD8+ cells before aerosol Ag challenge. Neither the genetic absence of IL-4, IL-4Rα chain, STAT-6, IFN-γ, or IL-12p40 nor mAb blockade of IFN-γ, IL-3, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17A, IL-12p40, or IL-12p40Rβ1 before Ag challenge in WT mice reduces the pulmonary MCp increase. However, sensitized and Ag-challenged IL-9-deficient mice and sensitized WT mice given mAb to IL-9 just before Ag challenge show significant reductions in elicited lung MCp/106 mononuclear cells of 47 and 66%, respectively. CD1d-deficient mice and WT mice receiving anti-CD1d before Ag challenge also show significant reductions of 65 and 59%, respectively, in elicited lung MCp/106 mononuclear cells, revealing an additional requirement for MCp recruitment. However, in Jα18-deficient mice, which lack only type 1 or invariant NKT cells, the increase in the numbers of lung MCp with Ag challenge was intact, indicating that their recruitment must be mediated by type 2 NKT cells. Furthermore, anti-CD1d treatment of IL-9-deficient mice or anti-IL-9 treatment of CD1d-deficient mice does not further reduce the significant partial impairment of MCp recruitment occurring with a single deficiency. These findings implicate type 2 NKT cells and IL-9 as central regulators that function in the same pathway mediating the Ag-induced increase in numbers of pulmonary MCp.