The potential of various lipopolysaccharides to release IL-8 and G-CSF

The chemokine regulated on activation normal T cells expressed and secreted (RANTES) has been implicated in eosinophil chemotaxis in asthma and allergic diseases, which are thought to be T helper (Th) type 2-dominated diseases. However, adoptive transfer of Th1 cells in mice upregulates RANTES gene expression in the lung, and increased RANTES expression has been documented in several Th1 cell-dominated conditions that are associated with neutrophilia. The in vivo role of RANTES in the pathogenesis of disease processes is not well understood. To determine the effect of RANTES expression alone in vivo, we generated transgenic mice that overexpress RANTES specifically in the lung in an inducible fashion. The airways of the transgenic mice overexpressing RANTES displayed a significant increase in neutrophil infiltration compared with that in control mice. The increased airway neutrophilia was also evident when the transgenic mice were tested in a murine model of allergic airway inflammation. RANTES expression also induced expression of the chemokine genes macrophage inflammatory protein-2, 10-kDa interferon-gamma-inducible protein, and monocyte chemoattractant protein-1 in the lungs of the transgenic mice. Our studies highlight a hitherto unappreciated role for RANTES in neutrophil trafficking during inflammation. Thus increased RANTES expression, as observed during respiratory viral infections, may play an important role in the associated neutrophilia and exacerbations of asthma.     

Differential sensitivity to Itk kinase signals for T helper 2 cytokine production and chemokine-mediated migration.

Allergic asthma is dependent on chemokine-mediated Th2 cell migration and Th2 cytokine secretion into the lungs. The inducible T cell tyrosine kinase Itk regulates the production of Th2 cytokines as well as migration in response to chemokine gradients. Mice lacking Itk are resistant to developing allergic asthma. However, the role of kinase activity of Itk in the development of this disease is unclear. In addition, whether distinct Itk-derived signals lead to T cell migration and secretion of Th2 cytokines is also unknown. Using transgenic mice specifically lacking Itk kinase activity, we show that active kinase signaling is required for control of Th2 responses and development of allergic asthma. Moreover, dominant suppression of kinase Itk activity led to normal Th2 responses, but significantly reduced chemokine-mediated migration, resulting in prevention of allergic asthma. These observations indicate that signals required for Th2 responses and migration are differentially sensitive to Itk activity. Manipulation of Itk's activity can thus provide a new strategy to treat allergic asthma by differentially affecting migration of T cells into the lungs, leaving Th2 responses intact.     

TLR7 ligand prevents allergen-induced airway hyperresponsiveness and eosinophilia in allergic asthma by a MYD88-dependent and MK2-independent pathway

Asthma is one of the leading causes of childhood hospitalization, and its incidence is on the rise throughout the world. Currently, the standard treatment for asthma is the use of corticosteroids to try to suppress the inflammatory reaction taking place in the bronchial tree. Using a murine model of atopic allergic asthma employing a methacholine-hyperresponsive (A/J) as well as a hyporesponsive (C57BL/6) strain of mice sensitized and challenged with ovalbumin, we show that treatment with a synthetic Toll-like receptor 7 (TLR7) ligand (S-28463, a member of the imidazoquinoline family) prevents development of the asthmatic phenotype. Treatment with S-28463 resulted in a reduction of airway resistance and elastance following ovalbumin sensitization and challenge. This was accompanied by a dramatic reduction in infiltration of leukocytes, especially eosinophils, into the lungs of both C57BL/6 and A/J mice following OVA challenge. Treatment with S-28463 also abolished both the elevation in serum IgE level as well as the induction of IL-4, IL-5, and IL-13 by OVA challenge. The protective effects of S-28463 were also observed in MK2 knockout, but not MYD88 knockout, mice. We did not observe a switch in cytokine profile from T(H)2 to T(H)1, as both IL-12p70 and IFN-gamma levels were reduced following S-28463 treatment. These results clearly demonstrate the anti-inflammatory effect of imidazoquinolines in an allergic asthma model as well as the clinical potential of TLR7 ligands in the treatment of allergic diseases.     

Attenuation of immunological symptoms of allergic asthma in mice lacking the tyrosine kinase ITK

Allergic asthma patients manifest airway inflammation and some show increases in eosinophils, T(H)2 cells, and cytokines, increased mucous production in the lung, and elevated serum IgE. This T(H)2-type response suggests a prominent role for T(H)2 cells and their cytokines in the pathology of this disease. The Tec family nonreceptor tyrosine kinase inducible T cell kinase (ITK) has been shown to play a role in the differentiation and/or function of T(H)2-type cells, suggesting that ITK may represent a good target for the control of asthma. Using a murine model of allergic asthma, we show here that ITK is involved in the development of immunological symptoms seen in this model. We show that mice lacking ITK have drastically reduced lung inflammation, eosinophil infiltration, and mucous production following induction of allergic asthma. Notably, T cell influx into the lung was reduced in mice lacking ITK. T cells from ITK(-/-) mice also exhibited reduced proliferation and cytokine secretion, in particular IL-5 and IL-13, in response to challenge with the allergen OVA, despite elevated levels of total IgE and increased OVA-specific IgE responses. Our results suggest that the tyrosine kinase ITK preferentially regulates the secretion of the T(H)2 cytokines IL-5 and IL-13 and may be an attractive target for antiasthmatic drugs.     

SOCS-3在哮喘Th1／Th2免疫失衡中的作用研究进展

支气管哮喘（简称哮喘）是一种以Th1／Th2免疫失衡、Th2优势应答为特征的慢性气道炎症性疾病。细胞因子信号转导抑制因子3（SOCS-3）是一类与细胞因子JAK／STAT信号转导途径有关的负反馈调节因子,参与细胞固有免疫、获得性免疫和炎症反应。近年来研究发现,在哮喘的发生发展中SOCS-3均表现出分子水平或功能的异常,提示SOCS．3可作为哮喘诊断和治疗的新靶点。就SOCS-3与哮喘的关系研究进展进行综述,讨论其在哮喘Th1／Th2免疫失衡中的作用。     

Uteroglobin suppresses allergen-induced TH2 differentiation by down-regulating the expression of serum amyloid A and SOCS-3 genes

Allergen-induced airway inflammation may lead to allergic asthma, a chronic inflammatory disease of the respiratory system. Despite its high incidence, the majority of the world's population is unaffected by allergic airway inflammation most likely due to innate protective mechanism(s) in the respiratory system. The mammalian airway epithelia constitutively express uteroglobin (UG), a protein with potent anti-inflammatory and anti-chemotactic properties. We report here that UG binds to FPR2, a G-protein coupled receptor, inhibits chemotaxis, down-regulates SOCS-3 gene expression and STAT-1 activation, which are critical for the differentiation of T-helper 2 (T(H)2) cells that secrete pro-inflammatory T(H)2 cytokines. We propose that UG suppresses allergen-mediated activation of T(H)2 response by down-regulating the expression of genes that are critical for T(H)2 differentiation.     

In Vivo Disruption of TGF-β Signaling by Smad7 in Airway Epithelium Alleviates Allergic Asthma but Aggravates Lung Carcinogenesis in Mouse

Background

TGF-β has been postulated to play an important role in the maintenance of epithelial homeostasis and the development of epithelium-derived cancers. However, most of previous studies are mainly focused on the function of TGF-β in immune cells to the development of allergic asthma and how TGF-β signaling in airway epithelium itself in allergic inflammation is largely unknown. Furthermore, the in vivo TGF-β function specifically in the airway epithelium during lung cancer development has been largely elusive.

Methodology/Principal Findings

To evaluate the in vivo contribution of TGF-β signaling in lung epithelium to the development of allergic disease and lung cancer, we generated a transgenic mouse model with Smad7, an intracellular inhibitor of TGF-β signaling, constitutively expressed in mouse airway Clara cells using a mouse CC10 promoter. The mice were subjected to the development of OVA-induced allergic asthma and urethane-induced lung cancer. The Smad7 transgenic animals significantly protected from OVA-induced asthma, with reduced airway inflammation, airway mucus production, extracellular matrix deposition, and production of OVA-specific IgE. Further analysis of cytokine profiles in lung homogenates revealed that the Th2 cytokines including IL-4, IL-5 and IL-13, as well as other cytokines including IL-17, IL-1, IL-6, IP10, G-CSF, and GM-CSF were significantly reduced in the transgenic mice upon OVA induction. In contrast, the Smad7 transgenic animals had an increased incidence of lung carcinogenesis when subjected to urethane treatment.

Conclusion/Significance

These studies, therefore, demonstrate for the first time the in vivo function of TGF-β signaling specifically in airway epithelium during the development of allergic asthma and lung cancer.     

Sulforaphane inhibits the Th2 immune response in ovalbumin-induced asthma

Sulforaphane (1-isothiocyanato-4-(methylsulfinyl)-butane), belonging to a family of natural compounds that are abundant in broccoli, has received significant therapeutic interest in recent years. However, the molecular basis of its effects remains to be elucidated. In this study, we attempt to determine whether sulforaphane regulates the inflammatory response in an ovalbumin (OVA)-induced murine asthma model. Mice were sensitized with OVA, treated with sulforaphane, and then challenged with OVA. Sulforaphane administration significantly alleviated the OVA-induced airway hyperresponsiveness to inhaled methacholine. Additionally, sulforaphane suppressed the increase in the levels of SOCS-3 and GATA-3 and IL-4 expression in the OVA-challenged mice. Collectively, our results demonstrate that sulforaphane regulates Th2 immune responses. This sutdy provides novel insights into the regulatory role of sulforaphane in allergen-induced Th2 inflammation and airway responses, which indicates its therapeutic potential for asthma and other allergic diseases.     

Suppressor of cytokine signaling-1 has IFN-gamma-independent actions in T cell homeostasis

Suppressor of cytokine signaling (SOCS)-1 is a member of a family of proteins that negatively regulate cytokine signaling pathways. We have previously established that SOCS-1 is a key regulator of IFN-gamma signaling and that IFN-gamma is responsible for the complex inflammatory disease that leads to the death of SOCS-1-deficient mice. In this study, we provide evidence that SOCS-1 is also a critical regulator of IFN-gamma-independent immunoregulatory factors. Mice lacking both SOCS-1 and IFN-gamma, although outwardly healthy, have clear abnormalities in their immune system, including a reduced ratio of CD4:CD8 T cells in lymphoid tissues and increased expression of T cell activation markers. To examine the contribution of TCR Ag specificity to these immune defects, we have generated two lines of SOCS-1-deficient mice expressing a transgenic TCR specific for an exogenous Ag, OVA (OT-I and OT-II). Although TCR transgenic SOCS-1(-/-) mice have a longer lifespan than nontransgenic SOCS-1(-/-) mice, they still die as young adults with inflammatory disease and the TCR transgenic SOCS-1(-/-) T cells appear activated despite the absence of OVA. This suggests that both Ag-dependent and -independent mechanisms contribute to the disease in SOCS-1-deficient mice. Thus, SOCS-1 is a critical regulator of T cell activation and homeostasis, and its influence extends beyond regulating IFN-gamma signaling.     

Schistosoma japonicum peptide SJMHE1 suppresses airway inflammation of allergic asthma in mice

Helminths and their products can shape immune responses by modulating immune cells, which are dysfunctional in inflammatory diseases such as asthma. We previously identified SJMHE1, a small molecule peptide from the HSP60 protein of Schistosoma japonicum. SJMHE1 can inhibit delayed‐type hypersensitivity and collagen‐induced arthritis in mice. In the present study, we evaluated this peptide's potential intervention effect and mechanism on ovalbumin‐induced asthma in mice. SJMHE1 treatment suppressed airway inflammation in allergic mice, decreased the infiltrating inflammatory cells in the lungs and bronchoalveolar lavage fluid, modulated the production of pro‐inflammatory and anti‐inflammatory cytokines in the splenocytes and lungs of allergic mice, reduced the percentage of Th2 cells and increased the proportion of Th1 and regulatory T cells (Tregs). At the same time, Foxp3 and T‐bet expression increased, and GATA3 and RORγt decreased in the lungs of allergic mice. We proved that SJMHE1 can interrupt the development of asthma by diminishing airway inflammation in mice. The down‐regulation of Th2 response and the up‐regulation of Th1 and Tregs response may contribute to the protection induced by SJMHE1 in allergic mice. SJMHE1 can serve as a novel therapy for asthma and other allergic or inflammatory diseases.     

Computational and experimental analysis reveals a requirement for eosinophil-derived IL-13 for the development of allergic airway responses in C57BL/6 mice

Eosinophils are found in the lungs of humans with allergic asthma, as well as in the lungs of animals in models of this disease. Increasing evidence suggests that these cells are integral to the development of allergic asthma in C57BL/6 mice. However, the specific function of eosinophils that is required for this event is not known. In this study, we experimentally validate a dynamic computational model and perform follow-up experimental observations to determine the mechanism of eosinophil modulation of T cell recruitment to the lung during development of allergic asthma. We find that eosinophils deficient in IL-13 were unable to rescue airway hyperresponsiveness, T cell recruitment to the lungs, and Th2 cytokine/chemokine production in ΔdblGATA eosinophil-deficient mice, even if Th2 cells were present. However, eosinophil-derived IL-13 alone was unable to rescue allergic asthma responses in the absence of competence of other IL-13-producing cells. We further computationally investigate the role of other cell types in the production of IL-13, which led to the various predictions including early and late pulses of IL-13 during airway hyperresponsiveness. These experiments suggest that eosinophils and T cells have an interdependent relationship, centered on IL-13, which regulates T cell recruitment to the lung and development of allergic asthma.     

Defective thymocyte development and perturbed homeostasis of T cells in STAT-induced STAT inhibitor-1/suppressors of cytokine signaling-1 transgenic mice

Previous experiments have shown that STAT-induced STAT inhibitor-1 (SSI-1; also named suppressors of cytokine signaling-1 (SOCS-1) or Janus kinase binding protein) is predominantly expressed in lymphoid organs and functions in vitro as a negative regulator of cytokine signaling. To determine the function of SOCS-1 in vivo, we generated SSI-1 transgenic mice using the lck proximal promoter that drives transgene expression in T cell lineage. In thymocytes expressing SSI-1 transgene, tyrosine phosphorylation of STATs in response to cytokines such as IFN-gamma, IL-6, and IL-7 was inhibited, suggesting that SSI-1 suppresses cytokine signaling in primary lymphocytes. In addition, lck-SSI-1 transgenic mice showed a reduction in the number of thymocytes as a result of the developmental blocking during triple-negative stage. They also exhibited a relative increase in the percentage of CD4+ T cells, a reduction in the number of gammadelta T cells, as well as the spontaneous activation and increased apoptosis of peripheral T cells. Thus, enforced expression of SSI-1 disturbs the development of thymocytes and the homeostasis of peripheral T cells. All these features of lck-SSI-1 transgenic mice strikingly resemble the phenotype of mice lacking common gamma-chain or Janus kinase-3, suggesting that transgene-derived SSI-1 inhibits the functions of common gamma-chain-using cytokines. Taken together, these results suggest that SSI-1 can also inhibit a wide variety of cytokines in vivo.     

Vascular endothelial growth factor (VEGF) induces remodeling and enhances TH2-mediated sensitization and inflammation in the lung

Exaggerated levels of VEGF (vascular endothelial growth factor) are present in persons with asthma, but the role(s) of VEGF in normal and asthmatic lungs has not been defined. We generated lung-targeted VEGF(165) transgenic mice and evaluated the role of VEGF in T-helper type 2 cell (T(H)2)-mediated inflammation. In these mice, VEGF induced, through IL-13-dependent and -independent pathways, an asthma-like phenotype with inflammation, parenchymal and vascular remodeling, edema, mucus metaplasia, myocyte hyperplasia and airway hyper-responsiveness. VEGF also enhanced respiratory antigen sensitization and T(H)2 inflammation and increased the number of activated DC2 dendritic cells. In antigen-induced inflammation, VEGF was produced by epithelial cells and preferentially by T(H)2 versus T(H)1 cells. In this setting, it had a critical role in T(H)2 inflammation, cytokine production and physiologic dysregulation. Thus, VEGF is a mediator of vascular and extravascular remodeling and inflammation that enhances antigen sensitization and is crucial in adaptive T(H)2 inflammation. VEGF regulation may be therapeutic in asthma and other T(H)2 disorders.     

Suppressor of cytokine signaling-1 overexpression protects pancreatic beta cells from CD8+ T cell-mediated autoimmune destruction

In type 1 diabetes, cytokine action on beta cells potentially contributes to beta cell destruction by direct cytotoxicity, inducing Fas expression, and up-regulating class I MHC and chemokine expression to increase immune recognition. To simultaneously block beta cell responsiveness to multiple cytokines, we overexpressed suppressor of cytokine signaling-1 (SOCS-1). This completely prevented progression to diabetes in CD8(+) TCR transgenic nonobese diabetic (NOD) 8.3 mice without affecting pancreas infiltration and partially prevented diabetes in nontransgenic NOD mice. SOCS-1 appeared to protect at least in part by inhibiting TNF- and IFN-gamma-induced Fas expression on beta cells. Fas expression was up-regulated on beta cells in vivo in prediabetic NOD8.3 mice, and this was inhibited by SOCS-1. Additionally, IFN-gamma-induced class I MHC up-regulation and TNF- and IFN-gamma-induced IL-15 expression by beta cells were inhibited by SOCS-1, which correlated with suppressed 8.3 T cell proliferation in vitro. Despite this, 8.3 T cell priming in vivo appeared unaffected. Therefore, blocking beta cell responses to cytokines impairs recognition by CD8(+) T cells and blocks multiple mechanisms of beta cell destruction, but does not prevent T cell priming and recruitment to the islets. Our findings suggest that increasing SOCS-1 expression may be useful as a strategy to block CD8(+) T cell-mediated type 1 diabetes as well as to more generally prevent cytokine-dependent tissue destruction in inflammatory diseases.     

Vitamin D receptor-deficient mice fail to develop experimental allergic asthma

The active metabolite of vitamin D (1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3))) is known to modulate the immune response in Th1 cell-directed diseases. To investigate the role of vitamin D in Th2 cell-directed diseases, experimental allergic asthma was induced in vitamin D receptor (VDR) knockout and in wild-type (WT) mice. As expected, WT mice developed symptoms of airway inflammation with an influx of eosinophils, elevated Th2 cytokine levels, mucous production, and airway hyperresponsiveness. The administration of 1,25(OH)(2)D(3) had no effect on asthma severity. The only discernable effect of 1,25(OH)(2)D(3) on experimental allergic asthma in WT mice was an increased expression of two Th2-related genes (soluble CD23 and GATA-3) in lungs of BALB/c mice exposed to Ag through the nasal route only. By contrast, asthma-induced VDR knockout mice failed to develop airway inflammation, eosinophilia, or airway hyperresponsiveness, despite high IgE concentrations and elevated Th2 cytokines. The data suggest that although 1,25(OH)(2)D(3) induced these Th2-type genes, the treatment failed to have any affect on experimental asthma severity. However, VDR-deficient mice failed to develop experimental allergic asthma, suggesting an important role for the vitamin D endocrine system in the generation of Th2-driven inflammation in the lung.     

Peroxisome proliferator-activated receptor gamma ligands attenuate immunological symptoms of experimental allergic asthma

Asthma is characterized by a predominant T(H)2 type immune response to airborne allergens. Controlling T(H)2 cell function has been proposed as therapy for this disease. We show here that ligands for the nuclear receptor peroxisome proliferator activated receptor (PPAR)gamma significantly reduced the immunological symptoms of allergic asthma in a murine model of this disease. A PPARgamma ligand, 15-deoxy-delta(12,14)-prostaglandin J(2), significantly inhibited production of the T(H)2 type cytokine IL-5 from T cells activated in vitro. More importantly, in a murine model of allergic asthma, mice treated orally with ciglitazone, a potent synthetic PPARgamma ligand, had significantly reduced lung inflammation and mucous production following induction of allergic asthma. T cells from these ciglitazone treated mice also produced less IFNgamma, IL-4, and IL-2 upon rechallenge in vitro with the model allergen. Our results suggest that ligands for PPARgamma may be effective treatments for asthmatic patients.     

Breast milk-mediated transfer of an antigen induces tolerance and protection from allergic asthma

Allergic asthma is a chronic disease characterized by airway obstruction in response to allergen exposure. It results from an inappropriate T helper type 2 response to environmental airborne antigens and affects 300 million individuals. Its prevalence has increased markedly in recent decades, most probably as a result of changes in environmental factors. Exposure to environmental antigens during infancy is crucial to the development of asthma. Epidemiological studies on the relationship between breastfeeding and allergic diseases have reached conflicting results. Here, we have investigated whether the exposure of lactating mice to an airborne allergen affects asthma development in progeny. We found that airborne antigens were efficiently transferred from the mother to the neonate through milk and that tolerance induction did not require the transfer of immunoglobulins. Breastfeeding-induced tolerance relied on the presence of transforming growth factor (TGF)-beta during lactation, was mediated by regulatory CD4+ T lymphocytes and depended on TGF-beta signaling in T cells. In conclusion, breast milk-mediated transfer of an antigen to the neonate resulted in oral tolerance induction leading to antigen-specific protection from allergic airway disease. This study may pave the way for the design of new strategies to prevent the development of allergic diseases.     

Secretory leukocyte protease inhibitor plays an important role in the regulation of allergic asthma in mice

Secretory leukocyte protease inhibitor (SLPI) is an anti-inflammatory protein that is observed at high levels in asthma patients. Resiquimod, a TLR7/8 ligand, is protective against acute and chronic asthma, and it increases SLPI expression of macrophages in vitro. However, the protective role played by SLPI and the interactions between the SLPI and resiquimod pathways in the immune response occurring in allergic asthma have not been fully elucidated. To evaluate the role of SLPI in the development of asthma phenotypes and the effect of resiquimod treatment on SLPI, we assessed airway resistance and inflammatory parameters in the lungs of OVA-induced asthmatic SLPI transgenic and knockout mice and in mice treated with resiquimod. Compared with wild-type mice, allergic SLPI transgenic mice showed a decrease in lung resistance (p < 0.001), airway eosinophilia (p < 0.001), goblet cell hyperplasia (p < 0.001), and plasma IgE levels (p < 0.001). Allergic SLPI knockout mice displayed phenotype changes significantly more severe compared with wild-type mice. These phenotypes included lung resistance (p < 0.001), airway eosinophilia (p < 0.001), goblet cell hyperplasia (p < 0.001), cytokine levels in the lungs (p < 0.05), and plasma IgE levels (p < 0.001). Treatment of asthmatic transgenic mice with resiquimod increased the expression of SLPI and decreased inflammation in the lungs; resiquimod treatment was still effective in asthmatic SLPI knockout mice. Taken together, our study showed that the expression of SLPI protects against allergic asthma phenotypes, and treatment by resiquimod is independent of SLPI expression, displayed through the use of transgenic and knockout SLPI mice.