IL-13-induced chemokine responses in the lung: role of CCR2 in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 stimulates inflammatory and remodeling responses and contributes to the pathogenesis of human airways disorders. To further understand the cellular and molecular events that mediate these responses, we characterized the effects of IL-13 on monocyte chemotactic proteins (MCPs) and compared the tissue effects of transgenic IL-13 in mice with wild-type (+/+) and null (-/-) CCR2 loci. Transgenic IL-13 was a potent stimulator of MCP-1, -2, -3, and -5. This stimulation was not specific for MCPs because macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, MIP-2, MIP-3alpha, thymus- and activation-regulated chemokine, thymus-expressed chemokine, eotaxin, eotaxin 2, macrophage-derived chemokines, and C10 were also induced. The ability of IL-13 to increase lung size, alveolar size, and lung compliance, to stimulate pulmonary inflammation, hyaluronic acid accumulation, and tissue fibrosis, and to cause respiratory failure and death were markedly decreased, whereas mucus metaplasia was not altered in CCR2(-/-) mice. CCR2 deficiency did not decrease the basal or IL-13-stimulated expression of target matrix metalloproteinases or cathepsins but did increase the levels of mRNA encoding alpha1-antitrypsin, tissue inhibitor of metalloproteinase-1, -2, and -4, and secretory leukocyte proteinase inhibitor. In addition, the levels of bioactive and total TGF-beta(1) were decreased in lavage fluids from IL-13 transgenic mice with -/- CCR2 loci. These studies demonstrate that IL-13 is a potent stimulator of MCPs and other CC chemokines and document the importance of MCP-CCR2 signaling in the pathogenesis of the IL-13-induced pulmonary phenotype.     

Role of 5-lipoxygenase in IL-13-induced pulmonary inflammation and remodeling

Exaggerated levels of IL-13 and leukotriene (LT) pathway activation frequently coexist at sites of Th2 inflammation and in tissue fibrotic responses. However, the relationship(s) between the IL-13 and LTs in these responses have not been defined. We hypothesized that the 5-lipoxygenase (5-LO) pathway of LT metabolism plays an important role in the pathogenesis of IL-13-induced chronic inflammation and remodeling. To test this hypothesis, we evaluated the effects of IL-13 on components of the 5-LO metabolic and activation pathways. We also compared the effects of transgenic IL-13 in C57BL/6 mice with wild-type and null 5-LO genetic loci. These studies demonstrate that IL-13 increases the levels of mRNA encoding cytosolic phospholipase A(2), LTA(4) hydrolase, and 5-LO-activating protein without altering the expression of 5-LO, LTC(4) synthase, LTB(4) receptors 1 and 2, and cysteinyl-LT receptors 1 and 2. They also demonstrate that this activation is associated with the enhanced accumulation of LTB(4) but not of cysteinyl-LTs. Furthermore, they demonstrate that this stimulation plays a critical role in the pathogenesis of IL-13-induced inflammation, tissue fibrosis, and respiratory failure-induced death while inhibiting alveolar remodeling. Lastly, mechanistic insights are provided by demonstrating that IL-13-induced 5-LO activation is required for optimal stimulation and activation of TGF-beta(1) and the inhibition of matrix metalloproteinase-12. When viewed in combination, these studies demonstrate that 5-LO plays an important role in IL-13-induced inflammation and remodeling.     

IL-11 receptor alpha in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 is a major stimulator of inflammation and tissue remodeling at sites of Th2 inflammation. In Th2-dominant inflammatory disorders such as asthma, IL-11 is simultaneously induced. However, the relationship(s) between IL-11 and IL-13 in these responses has not been defined, and the role(s) of IL-11 in the genesis of the tissue effects of IL-13 has not been evaluated. We hypothesized that IL-11, signaling via the IL-11Ralpha-gp130 receptor complex, plays a key role in IL-13-induced tissue responses. To test this hypothesis we compared the expression of IL-11, IL-11Ralpha, and gp130 in lungs from wild-type mice and transgenic mice in which IL-13 was overexpressed in a lung-specific fashion. We simultaneously characterized the effects of a null mutation of IL-11Ralpha on the tissue effects of transgenic IL-13. These studies demonstrate that IL-13 is a potent stimulator of IL-11 and IL-11Ralpha. They also demonstrate that IL-13 is a potent stimulator of inflammation, fibrosis, hyaluronic acid accumulation, myofibroblast accumulation, alveolar remodeling, mucus metaplasia, and respiratory failure and death in mice with wild-type IL-11Ralpha loci and that these alterations are ameliorated in the absence of IL-11Ralpha. Lastly, they provide insight into the mechanisms of these processes by demonstrating that IL-13 stimulates CC chemokines, matrix metalloproteinases, mucin genes, and gob-5 and stimulates and activates TGF-beta1 via IL-11Ralpha-dependent pathways. When viewed in combination, these studies demonstrate that IL-11Ralpha plays a key role in the pathogenesis of IL-13-induced inflammation and remodeling.     

The C10/CCL6 chemokine and CCR1 play critical roles in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 is a potent stimulator of inflammation and tissue remodeling that plays a key role in the pathogenesis of a wide variety of human disorders. To further understand these responses, studies were undertaken to define the role(s) of the chemokine C10/CCL6 in the pathogenesis of IL-13-induced alterations in the murine lung. IL-13 was a very potent stimulator of C10/CCL6 mRNA and protein, and IL-13-induced inflammation, alveolar remodeling, and compliance alterations were markedly ameliorated after C10/CCL6 neutralization. Treatment with anti-C10/CCL6 decreased the levels of mRNA encoding matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of metalloproteinase-4 (TIMP-4) in lungs from wild-type mice. C10/CCL6 neutralization also decreased the ability of IL-13 to stimulate the production of monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, MMP-2, MMP-9, and cathepsins-K, -L, and -S and the ability of IL-13 to inhibit alpha1-antitrypsin. In accord with these findings, a targeted null mutation of CCR1, a putative C10/CCL6 receptor, also decreased IL-13-induced inflammation and alveolar remodeling and caused alterations in chemokines, proteases, and antiproteases comparable to those seen after C10/CCL6 neutralization. These C10/CCL6 and CCR1 manipulations did not alter the production of transgenic IL-13. These studies demonstrate that IL-13 is a potent stimulator of C10/CCL6 and highlight the importance of C10/CCL6 and signaling via CCR1 in the pathogenesis of the IL-13-induced pulmonary phenotype. They also describe a C10/CCL6 target gene cascade in which C10/CCL6 induction is required for optimal IL-13 stimulation of selected chemokines (monocyte chemoattractant protein-1 and MIP-1alpha) and proteases (MMP-2, MMP-9, and cathepsins-K, -L, and -S) and the inhibition of alpha1-antitrypsin.     

IL-17、sICAM-1在COPD炎性机制中的作用研究

目的:探讨IL-17和sICAM-1与COPD之间的关系,观察COPD患者和对照组血浆中IL-17、sICAM-1的水平并分析其相关性。方法:30例COPD病例组(急性加重期和稳定期)、25例正常对照组,测定肺功能;采集外周静脉血用酶联免疫吸附法(ELISA)测定血浆中IL-17及sICAM-1的水平。结果:1、COPD急性加重期患者血浆中IL-17的浓度(202.56±68.52pg/mL)明显高于稳定期的浓度(160.56±53.53 pg/mL);COPD急性加重期和稳定期患者血浆中IL-17的浓度明显高于健康对照组的浓度(68.12±12.41pg/mL),均有显著性差异(P0.05)。2、COPD急性加重期患者血浆中sICAM-1的浓度(255.78±141.50ng/L)明显高于稳定期的浓度(170.68±97.70ng/L);COPD急性加重期和稳定期患者血浆中sICAM-1的浓度明显高于健康对照组的浓度(56.62±18.01ng/mL),均有显著性差异(P0.05)。3、COPD患者急性加重期IL-17与sICAM-1的水平均升高。COPD急性加重期组和稳定期患者血浆中IL-17与血浆中sICAM-1呈正相关(r=0.981,P0.05;r=0.664,P0.05)。结论:IL-17、sICAM-参与了COPD的发病,并且IL-17、sICAM-1水平可能与COPD严重程度呈正相关。     

A role for STAT5 in the pathogenesis of IL-2-induced glucocorticoid resistance

Glucocorticoids (GC) are highly effective in the control of diseases associated with T cell activation. However, a subset of individuals is GC insensitive. Previous studies have demonstrated that IL-2 can induce steroid resistance in mouse T cells. However, the mechanism for this phenomenon is unknown. In the current study we found that the murine cell line (HT-2) is steroid resistant when incubated with IL-2, but steroid sensitive when grown in IL-4. Furthermore, when HT-2 cells are treated with IL-2, the glucocorticoid receptor (GCR) does not translocate to the cell nucleus after dexamethasone treatment. In contrast, the GCR in IL-4-stimulated HT-2 cells does translocate into the cell nucleus after dexamethasone treatment. IL-2-induced steroid insensitivity in HT-2 cells appears to be a signaling event as the effects of IL-2 on nuclear translocation of the GCR occurred within 30 min even in the presence of cycloheximide. Indeed, preincubation of HT-2 cells with a Janus-associated kinase 3 inhibitor restored nuclear translocation of the GCR even in the presence of IL-2. Immunoprecipitation experiments revealed that phosphorylated STAT5 and GCR formed immune complexes. This association may lead to retardation of GCR nuclear translocation because IL-2 was not able to induce steroid insensitivity in splenocytes from STAT5 knockout mice. This study demonstrates a novel role for STAT5 in IL-2-induced steroid insensitivity.     

IL-13 receptor alpha2 selectively inhibits IL-13-induced responses in the murine lung

IL-13 is a critical cytokine at sites of Th2 inflammation. In these locations it mediates its effects via a receptor complex, which contains IL-4Ralpha and IL-13Ralpha1. A third, high-affinity IL-13 receptor, IL-13Ralpha2, also exists. Although it was initially felt to be a decoy receptor, this has not been formally demonstrated and the role(s) of this receptor has recently become controversial. To define the role(s) of IL-13Ralpha2 in IL-13-induced pulmonary inflammation and remodeling, we compared the effects of lung-targeted transgenic IL-13 in mice with wild-type and null IL-13Ralpha2 loci. We also investigated the effect of IL-13Ralpha2 deficiency on the OVA-induced inflammatory response. In this study, we show that in the absence of IL-13Ralpha2, IL-13-induced pulmonary inflammation, mucus metaplasia, subepithelial fibrosis, and airway remodeling are significantly augmented. These changes were accompanied by increased expression and production of chemokines, proteases, mucin genes, and TGF-beta1. Similarly, an enhanced inflammatory response was observed in an OVA-induced phenotype. In contrast, disruption of IL-13Ralpha2 had no effect on the tissue effects of lung-targeted transgenic IL-4. Thus, IL-13Ralpha2 is a selective and powerful inhibitor of IL-13-induced inflammatory, remodeling, and physiologic responses in the murine lung.     

CCR5 blockade modulates inflammation and alloimmunity in primates

Pharmacologic antagonism of CCR5, a chemokine receptor expressed on macrophages and activated T cells, is an effective antiviral therapy in patients with macrophage-tropic HIV infection, but its efficacy in modulating inflammation and immunity is only just beginning to be investigated. In this regard, the recruitment of CCR5-bearing cells into clinical allografts is a hallmark of acute rejection and may anticipate chronic rejection, whereas conventionally immunosuppressed renal transplant patients homozygous for a nonfunctional Delta32 CCR5 receptor rarely exhibit late graft loss. Therefore, we explored the effects of a potent, highly selective CCR5 antagonist, Merck's compound 167 (CMPD 167), in an established cynomolgus monkey cardiac allograft model. Although perioperative stress responses (fever, diminished activity) and the recruitment of CCR5-bearing leukocytes into the graft were markedly attenuated, anti-CCR5 monotherapy only marginally prolonged allograft survival. In contrast, relative to cyclosporine A monotherapy, CMPD 167 with cyclosporine A delayed alloantibody production, suppressed cardiac allograft vasculopathy, and tended to further prolong graft survival. CCR5 therefore represents an attractive therapeutic target for attenuating postsurgical stress responses and favorably modulating pathogenic alloimmunity in primates, including man.     

Role of the chemokine receptors CCR1, CCR2 and CCR4 in the pathogenesis of experimental dengue infection in mice

Dengue virus (DENV), a mosquito-borne flavivirus, is a public health problem in many tropical countries. Recent clinical data have shown an association between levels of different chemokines in plasma and severity of dengue. We evaluated the role of CC chemokine receptors CCR1, CCR2 and CCR4 in an experimental model of DENV-2 infection in mice. Infection of mice induced evident clinical disease and tissue damage, including thrombocytopenia, hemoconcentration, lymphopenia, increased levels of transaminases and pro-inflammatory cytokines, and lethality in WT mice. Importantly, infected WT mice presented increased levels of chemokines CCL2/JE, CCL3/MIP-1α and CCL5/RANTES in spleen and liver. CCR1^-/- mice had a mild phenotype with disease presentation and lethality similar to those of WT mice. In CCR2^-/- mice, lethality, liver damage, levels of IL-6 and IFN-γ, and leukocyte activation were attenuated. However, thrombocytopenia, hemoconcentration and systemic TNF-α levels were similar to infected WT mice. Infection enhanced levels of CCL17/TARC, a CCR4 ligand. In CCR4^-/- mice, lethality, tissue injury and systemic inflammation were markedly decreased. Despite differences in disease presentation in CCR-deficient mice, there was no significant difference in viral load. In conclusion, activation of chemokine receptors has discrete roles in the pathogenesis of dengue infection. These studies suggest that the chemokine storm that follows severe primary dengue infection associates mostly to development of disease rather than protection.     

Suppressive effect of IL-4 on IL-13-induced genes in mouse lung

Although IL-4 signals through two receptors, IL-4R alpha/common gamma-chain (gamma(c)) and IL-4R alpha/IL-13R alpha1, and only the latter is also activated by IL-13, IL-13 contributes more than IL-4 to goblet cell hyperplasia and airway hyperresponsiveness in murine asthma. To determine whether unique gene induction by IL-13 might contribute to its greater proasthmatic effects, mice were inoculated intratracheally with IL-4 or IL-13, and pulmonary gene induction was compared by gene microarray and real-time PCR. Only the collagen alpha2 type VI (Ca2T6) gene and three small proline-rich protein (SPRR) genes were reproducibly induced > 4-fold more by IL-13 than by IL-4. Preferential IL-13 gene induction was not attributable to B cells, T cells, or differences in cytokine potency. IL-4 signaling through IL-4R alpha/gamma(c) suppresses Ca2T6 and SPRR gene expression in normal mice and induces these genes in RAG2/gamma(c)-deficient mice. Although IL-4, but not IL-13, induces IL-12 and IFN-gamma, which suppress many effects of IL-4, IL-12 suppresses only the Ca2T6 gene, and IL-4-induced IFN-gamma production does not suppress the Ca2T6 or SPRR genes. Thus, IL-4 induces genes in addition to IL-12 that suppress STAT6-mediated SPRR gene induction. These results provide a potential explanation for the dominant role of IL-13 in induction of goblet cell hyperplasia and airway hyperresponsiveness in asthma.     

IL-12 reduces the severity of Sendai virus-induced bronchiolar inflammation and remodeling

The goal of this research was to determine whether differential pulmonary IL-12 gene expression controls susceptibility to Sendai virus-induced chronic airway inflammation and fibrosis in inbred rat strains. Sendai virus-resistant F344 rats and susceptible BN rats were studied from 1 to 14 days following virus inoculation. F344 rats had 3.4-fold higher IL-12 mRNA levels detected by real-time PCR in lung than BN rats as early as two days following inoculation. This increase in mRNA was associated at two days with increased total IL-12 protein and with a 2-fold increase in numbers of bronchiolar, OX-6-positive dendritic cells and an increased number of IL-12 p40-positive, bronchiolar macrophages and dendritic cells (p<0.05). Virus-susceptible BN rats treated with 3 mug of recombinant, mouse IL-12 intraperitoneally at the time of virus inoculation had a 22.1% decrease in severity of chronic bronchiolar inflammation and a 23.8% decrease in fibrosis compared to virus-inoculated BN rats treated with saline. IL-12 treatment induced increased IFN-gamma mRNA and protein expression after virus inoculation (p<0.05). The results demonstrate that there is differential pulmonary IL-12 gene expression between virus-susceptible and resistant rat strains and that IL-12 treatment can provide significant protection from virus-induced chronic airway inflammation and remodeling during early life.     

Role of IL-10 in the resolution of airway inflammation

IL-10 can be considered an important agent in the resolution of inflammation. Originally named "cytokine synthesis inhibitory factor" for its ability to inhibit IFN-gamma and IL-2 production in Th2 cells, it is secreted by monocytes, macrophages, mast cells, T and B lymphocytes, and dendritic cells (DCs). IL-10 production and release by monocytic cells in response to allergic challenge is upregulated by TNF-alpha, and by negative feedback regulation of itself. However, it is also secreted by T regulatory cells (Tregs), under the control of IL-2. Importantly in the context of asthma, IL-10 inhibits eosinophilia, by suppression of IL-5 and GM-CSF, by direct effects on eosinophil apoptosis, and effects on cell proliferation through down-regulation of IL-1. A number of its cytokine suppressive characteristics are now thought to occur through its upregulation of suppressor of cytokine signaling (SOCS)-3. IL-10 is also a suppressor of nitric oxide (NO) production, which may have ramifications for its role in airway inflammatory diseases. Initial clinical trials have demonstrated relative safety and few clinically adverse events at doses of recombinant human IL-10 below 50 microg/kg, with mixed success in treatment of patients with inflammatory bowel disease and psoriasis. However, both steroid therapy and allergen specific immunotherapy are known to elevate endogenous IL-10 levels, which may account for their efficacy, suggesting that further study of IL-10 as a target for treatment of airway inflammatory diseases such as asthma and COPD is warranted.     

Role of insulin-like growth factor-I in allergen-induced airway inflammation and remodeling

Insulin-like growth factor (IGF)-I is known to act on fibroblasts as a progression factor to push cells toward proliferation and activation to synthesize collagen. Subepithelial fibrosis, collagen deposition at the lamina reticularis, is part of the process of so-called remodeling and is a characteristic finding in the asthmatic airway. To study the role of IGF in the evolution of asthma, we used a model that involved immunization of mice with ovalbumin and alum, followed by an inhaled challenge of ovalbumin. IGF-I neutralizing antibody was continuously infused with an osmotic pump. Pulmonary function was analyzed using whole-body plethysmography before and after acetylcholine administration. It was found that OVA inhalation induced IGF-I expression at the site of the airway. IGF-I neutralizing Ab inhibited the elevation of airway resistance, airway inflammation, and an increase in airway wall thickening. The depression of ICAM-1 expression was accompanied by a diminution in airway inflammation. In conclusion, these results suggest that IGF-I is likely to be an important mediator of inflammation and remodeling in the asthmatic airway.     

Aspirin and salicylates inhibit the IL-4- and IL-13-induced activation of STAT6.

Allergic diseases, including asthma, represent a major threat to human health. Over the three last decades, their incidence has risen in western countries. Aspirin treatment has been shown to improve allergic diseases, especially asthma, and the decreased use of aspirin has been hypothesized to contribute to the increase in childhood asthma. Because salicylate compounds suppress a number of enzymatic activities, and signaling through IL-4R participates in the development of allergic responses, we tested the effect of salicylates on IL-4 signal transduction. We found that treatment of cell lines and primary cells with aspirin and salicylates, but not acetaminophen, inhibited the activation of STAT6 by IL-4 and IL-13. This effect correlated with the inhibition of IL-4-induced CD23 expression. Although salicylates inhibited the in vivo activation of Janus kinases, their kinase activity was not affected in vitro by salicylates, suggesting that other kinases were involved in IL-4-induced STAT6 activation. Furthermore, we found that an Src kinase was involved in STAT6 activation because 1) Src kinase activity was induced by IL-4, 2) Src kinase activity, but not Janus kinase, was inhibited by salicylates in vitro, 3) cells expressing viral Src had constitutive STAT6 phosphorylation, and 4) cells lacking Src showed low STAT6 phosphorylation in response to IL-4. Because STAT6 activation by IL-4 and IL-13 participates in the development of allergic diseases, our results provide a mechanism to explain the beneficial effects of aspirin and salicylate treatment of these diseases.     

Role of IL-18 in acute lung inflammation.

We have examined the role of IL-18 after acute lung inflammation in rats caused by intrapulmonary deposition of IgG immune complexes. Constitutive IL-18 mRNA and protein expression (precursor form, 26 kDa) were found in normal rat lung, whereas in inflamed lungs, IL-18 mRNA was up-regulated; in bronchoalveolar (BAL) fluids, the 26-kDa protein form of IL-18 was increased at 2-4 h in inflamed lungs and remained elevated at 24 h, and the "mature" protein form of IL-18 (18 kDa) appeared in BAL fluids 1-8 h after onset of inflammation. ELISA studies confirmed induction of IL-18 in inflamed lungs (in lung homogenates and in BAL fluids). Prominent immunostaining for IL-18 was found in alveolar macrophages from inflamed lungs. When rat lung macrophages, fibroblasts, type II cells, and endothelial cells were cultured in vitro with LPS, only the first two produced IL-18. Intratracheal administration of rat recombinant IL-18 in the lung model caused significant increases in lung vascular permeability and in BAL content of neutrophils and in BAL content of TNF-alpha, IL-1beta, and cytokine-induced neutrophil chemoattractant, whereas intratracheal instillation of anti-IL-18 greatly reduced these changes and prevented increases in BAL content of IFN-gamma. Intratracheal administration of the natural antagonist of IL-18, IL-18 binding protein, resulted in suppressed lung vascular permeability and decreased BAL content of neutrophils, cytokines, and chemokines. These findings suggest that endogenous IL-18 functions as a proinflammatory cytokine in this model of acute lung inflammation, serving as an autocrine activator to bring about expression of other inflammatory mediators.     

Role of CD69 in the pathogenesis of elastase-induced pulmonary inflammation and emphysema

Cluster of differentiation 69 (CD69), known as an early activation marker of lymphocytes, has been demonstrated to regulate inflammatory events in various disease models. Although the increased number of CD69-expressed T lymphocytes in the lungs of patients with chronic obstructive pulmonary disease (COPD) has been reported, a functional role of CD69 in the pathogenesis of COPD remains unknown. To address to this question, CD69-deficient (CD69KO) mice and wild-type (WT) mice were subjected to a mouse model of porcine pancreatic elastase (PPE)-induced pulmonary inflammation and emphysema. In the two genotypes, PPE increased counts of macrophages, neutrophils and lymphocytes in bronchoalveolar lavage fluid (BALF) and induced emphysematous changes in the lung, whereas those two pathological signs were significantly enhanced in CD69KO mice compared to WT mice. Moreover, the PPE-induced levels of IL-17 and IL-6 in BALF were significantly higher in CD69KO mice than in WT mice at the acute inflammatory phase. Immunofluorescent studies showed that IL-17 and IL-6 were predominantly expressed in CD4⁺ and γδ T cells and macrophages, respectively. Concomitant administration of IL-17- and IL-6-neutralizing antibodies significantly attenuated the PPE-induced emphysematous changes in the two genotypes. These findings suggest that CD69 negatively regulates the development of PPE-induced emphysema in part at least through modulating function of IL-17-producing T cells.