In vivo role of p38 mitogen-activated protein kinase in mediating the anti-inflammatory effects of CpG oligodeoxynucleotide in murine asthma

Pathogenesis of allergic diseases and implications for therapeutic interventions

Allergic diseases such as allergic rhinitis (AR), allergic asthma (AAS), atopic dermatitis (AD), food allergy (FA), and eczema are systemic diseases caused by an impaired immune system. Accompanied by high recurrence rates, the steadily rising incidence rates of these diseases are attracting increasing attention. The pathogenesis of allergic diseases is complex and involves many factors, including maternal-fetal environment, living environment, genetics, epigenetics, and the body's immune status. The pathogenesis of allergic diseases exhibits a marked heterogeneity, with phenotype and endotype defining visible features and associated molecular mechanisms, respectively. With the rapid development of immunology, molecular biology, and biotechnology, many new biological drugs have been designed for the treatment of allergic diseases, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-5, and anti-thymic stromal lymphopoietin (TSLP)/IL-4, to control symptoms. For doctors and scientists, it is becoming more and more important to understand the influencing factors, pathogenesis, and treatment progress of allergic diseases. This review aimed to assess the epidemiology, pathogenesis, and therapeutic interventions of allergic diseases, including AR, AAS, AD, and FA. We hope to help doctors and scientists understand allergic diseases systematically.

FIP-fve Stimulates Cell Proliferation and Enhances IL-2 Release by Activating MAP2K3/p38α (MAPK14) Signaling Pathway in Jurkat E6-1 Cells

FIP-fve, a fungal fruiting body protein from Flammulina velutipes, has potential immunomodulatory properties. Here, we investigated the immunomodulation mechanism of FIP-fve in Jurkat E6-1 cells by conducting a cell viability assay and IL-2 release assay. Kinase inhibitors experiment and proteomics analysis were also involved in the mechanism study. It was found that FIP-fve stimulated cell proliferation and enhanced IL-2 secretion in a dose-dependent manner in Jurkat E6-1 cells. Unbiased high-throughput proteomics analysis showed that 4 T cell immune activation markers, including ZAP-70, CD69, CD82, and KIF23, were upregulated in response to FIP-fve treatment. Further pathway analysis indicated that MAP2K3/p38 pathway-related proteins, including MAP2K, p38, ELK, AATF, FOS, and JUN-B, were unregulated. In addition, losmapimod (p38 inhibitor) and gossypetin (MAP2K3 inhibitor) inhibited FIP-fve enhanced cell proliferation and IL-2 release in Jurkat E6-1 cells. Our results demonstrate that FIP-fve stimulates cell proliferation and enhances IL-2 secretion through MAP2K3/p38α activation.

Intranasal curcumin protects against LPS-induced airway remodeling by modulating toll-like receptor-4 (TLR-4) and matrixmetalloproteinase-9 (MMP-9) expression via affecting MAP kinases in mouse model

OBJECTIVE

Bacterial infections can exacerbate asthmatic inflammation depending on lipopolysaccharide (LPS) composition, the outermost component of cell wall, its exposure timings as well as host's immune status. In present study, Balb/c mice were exposed to antigen (ovalbumin) and LPS simultaneously to establish an asthmatic model. Curcumin (diferuloylmethane), well known for its anti-inflammatory potential, was administered through intranasal route 1 h before LPS and OVA (ovalbumin) exposure to evaluate its efficacy against airway structural changes.

METHODS

Inflammatory cell infiltration in lungs was measured by flow cytometry and further eosinophils were especially measured by immunofluorescence detection of major basic protein (MBP) as marker of eosinophilc granule protein. We also measured reactive oxygen species (ROS) in BALF by spectrofluorometry. MMP-9 activity was evaluated by gelatin zymography and mRNA expressions of MMP-9, TIMP-1, TGF-β1, IL-13, Collagen-1 and TLR-4 were measured in lungs. Protein expression of MAP kinases (P-ERK, P-JNK, P-p38), TLR-4, Cox-2, Lox-5 and Eotaxin was measured by western blotting. Hydroxyproline level and masson's trichrome staining were used to evaluate collagen deposition in lung.

RESULTS

Exposure to LPS (0.1 µg) exacerbates airway inflammation and induces structural changes in lungs by enhanced ROS production, collagen deposition, expression of genes involved in airway remodeling and activation of MAP kinases pathway enzymes. Intranasal curcumin pretreatment had significantly suppressed inflammatory mediators and airway remodeling proteins.

CONCLUSION

Our results strongly suggest that intranasal curcumin effectively protects LPS-induced airway inflammation and structural changes by modulating genes involved in airway remodeling in safer way; hence, it can be considered as supplementary alternative towards asthma treatments.

Inhibitory/suppressive oligodeoxynucleotide nanocapsules as simple oral delivery devices for preventing atopic dermatitis in mice

Here, we report a simple and low-cost oral oligodeoxynucleotide (ODN) delivery system targeted to the gut Peyer's patches (PPs). This system requires only Dulbecco's modified eagle's medium, calcium chloride, ODNs, and basic laboratory equipment. ODN nanocapsules (ODNcaps) were directly delivered to the PPs through oral administration and were taken up by macrophages in the PPs, where they induced an immune response. Long-term continuous oral dosing with inhibitory/suppressive ODNcaps (iODNcaps, "iSG3caps" in this study) was evaluated using an atopic dermatitis mouse model to visually monitor disease course. Administration of iSG3caps improved skin lesions and decreased epidermal thickness. Underlying this effect is the ability of iSG3 to bind to and prevent phosphorylation of signal transducer and activator of transcription 6, thereby blocking the interleukin-4 signaling cascade mediated by binding of allergens to type 2 helper T cells. The results of our iSG3cap oral delivery experiments suggest that iSG3 may be useful for treating allergic diseases.

Role of infections in the induction and development of asthma: genetic and inflammatory drivers

Genetic and environmental factors interact to initiate and even maintain the course of asthma. As one of the highly risky environmental factors, infections in predisposed individuals can promote asthma development and exacerbations and/or prolong symptoms. This review will describe our current understanding of the genetic markers of innate immunity in the induction and development of asthma, the diverse roles of infections in modulating allergic inflammation, host susceptibility to infections and subsequent acute exacerbations in an allergic setting, and the therapeutic or preventive implications of existing knowledge. Current challenges and future directions in basic and clinical research of asthma are also discussed.

The toll-like receptor 9 agonist, CpG-oligodeoxynucleotide 1826, ameliorates cardiac dysfunction after trauma-hemorrhage

Cardiovascular collapse is the major factor contributing to the mortality of trauma-hemorrhage (T-H) patients. Toll-like receptors (TLRs) play a critical role in T-H-induced cardiac dysfunction. This study evaluated the role of TLR9 agonist, CpG-oligodeoxynucleotide (ODN) 1826, in cardiac functional recovery after T-H. Trauma-hemorrhage was induced in a murine model by soft tissue injury and blood withdrawals from the jugular vein to a mean arterial pressure of 35 ± 5 mmHg. Mice were treated with CpG-ODN 1826 (10 μg/30 g body weight) by intraperitoneal injection 1 h before T-H (n = 5-8/group). Hemodynamic parameters were measured before, during hemorrhage, and at 60 min after T-H. Trauma-hemorrhage significantly decreased the mean arterial pressure and left ventricular pressure compared with sham controls. In contrast, CpG-ODN administration significantly attenuated the decrease in arterial pressure and left ventricular pressure due to T-H. Trauma-hemorrhage markedly decreased myocardial levels of phosphorylated Akt by 57.9%. However, CpG-ODN treatment significantly blunted the decrement in phospho-Akt by activating the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. The PI3K inhibitor LY294002 partially abolished CpG-induced cardioprotection, indicating that additional signaling pathways are involved in the protective effect of CpG-ODN after T-H. We observed that CpG-ODN treatment also significantly attenuated the decrease in myocardial phospho-ERK levels after T-H. Inhibition of ERK by U0126 also partially abolished the cardioprotective effect of CpG-ODN after T-H. Our data suggest that CpG-ODN significantly attenuates T-H-induced cardiac dysfunction. The mechanisms involve activation of both PI3K/Akt and ERK signaling pathways. The TLR9 agonist, CpG-ODN 1826, may provide a novel treatment strategy for preventing or managing cardiac dysfunction and enhancing recovery in T-H patients.

FcgammaRIIb inhibits allergic lung inflammation in a murine model of allergic asthma

Allergic asthma is characterized by airway eosinophilia, increased mucin production and allergen-specific IgE. Fc gamma receptor IIb (FcγRIIb), an inhibitory IgG receptor, has recently emerged as a negative regulator of allergic diseases like anaphylaxis and allergic rhinitis. However, no studies to date have evaluated its role in allergic asthma. Our main objective was to study the role of FcγRIIb in allergic lung inflammation. We used a murine model of allergic airway inflammation. Inflammation was quantified by BAL inflammatory cells and airway mucin production. FcγRIIb expression was measured by qPCR and flow cytometry and the cytokines were quantified by ELISA. Compared to wild type animals, FcγRIIb deficient mice mount a vigorous allergic lung inflammation characterized by increased bronchoalveolar lavage fluid cellularity, eosinophilia and mucin content upon ragweed extract (RWE) challenge. RWE challenge in sensitized mice upregulated FcγRIIb in the lungs. Disruption of IFN-γ gene abrogated this upregulation. Treatment of naïve mice with the Th1-inducing agent CpG DNA increased FcγRIIb expression in the lungs. Furthermore, treatment of sensitized mice with CpG DNA prior to RWE challenge induced greater upregulation of FcγRIIb than RWE challenge alone. These observations indicated that RWE challenge upregulated FcγRIIb in the lungs by IFN-γ- and Th1-dependent mechanisms. RWE challenge upregulated FcγRIIb on pulmonary CD14+/MHC II+ mononuclear cells and CD11c+ cells. FcγRIIb deficient mice also exhibited an exaggerated RWE-specific IgE response upon sensitization when compared to wild type mice. We propose that FcγRIIb physiologically regulates allergic airway inflammation by two mechanisms: 1) allergen challenge mediates upregulation of FcγRIIb on pulmonary CD14+/MHC II+ mononuclear cells and CD11c+ cells by an IFN-γ dependent mechanism; and 2) by attenuating the allergen specific IgE response during sensitization. Thus, stimulating FcγRIIb may be a therapeutic strategy in allergic airway disorders.

p38 Mitogen-activated protein kinase signalling regulates vascular inflammation and epithelial barrier dysfunction in an experimental model of radiation-induced colitis

BACKGROUND

: Microvascular injury and epithelial barrier dysfunction are rate-limiting aspects in radiation enteropathy. This study examined the role of p38 mitogen-activated protein kinase (p38 MAPK) signalling in radiation-induced colitis in an experimental model.

METHODS

: The p38 MAPK inhibitor SB239063 was administered to mice immediately before exposure to 20 Gy radiation. Leucocyte- and platelet-endothelium interactions in the colonic microcirculation were assessed by intravital microscopy. Levels of myeloperoxidase (MPO) and CXC chemokines (macrophage inflammatory protein (MIP) 2 and cytokine-induced neutrophil chemoattractant (KC)), and albumin leakage were quantified 16 h after irradiation.

RESULTS

: Irradiation induced an increase in leucocyte and platelet recruitment, MPO activity, CXC chemokine levels and intestinal leakage. Inhibition of p38 MAPK by SB239063 decreased radiation-induced leucocyte and platelet recruitment (leucocyte rolling and adhesion by 70 and 90 per cent, both P < 0.001; that of platelets by 70 and 74 per cent, both P < 0.001). It also reduced radiation-provoked increases in colonic MPO activity by 88 per cent (P < 0.001), formation of MIP-2 and KC by 72 and 74 per cent respectively (P = 0.003 and P < 0.001), and intestinal leakage by 81 per cent (P < 0.001).

CONCLUSION

: p38 MAPK is an important signalling pathway in radiation-induced colitis.

Allergen challenge induces Ifng dependent GTPases in the lungs as part of a Th1 transcriptome response in a murine model of allergic asthma

According to the current paradigm, allergic airway inflammation is mediated by Th2 cytokines and pro-inflammatory chemokines. Since allergic inflammation is self-limited, we hypothesized that allergen challenge simultaneously induces anti-inflammatory genes to counter-balance the effects of Th2 cytokines and chemokines. To identify these putative anti-inflammatory genes, we compared the gene expression profile in the lungs of ragweed-sensitized mice four hours after challenge with either PBS or ragweed extract (RWE) using a micro-array platform. Consistent with our hypothesis, RWE challenge concurrently upregulated Th1-associated early target genes of the Il12/Stat4 pathway, such as p47 and p65 GTPases (Iigp, Tgtp and Gbp1), Socs1, Cxcl9, Cxcl10 and Gadd45g with the Th2 genes Il4, Il5, Ccl2 and Ccl7. These Th1-associated genes remain upregulated longer than the Th2 genes. Augmentation of the local Th1 milieu by administration of Il12 or CpG prior to RWE challenge further upregulated these Th1 genes. Abolition of the Th1 response by disrupting the Ifng gene increased allergic airway inflammation and abrogated RWE challenge-induced upregulation of GTPases, Cxcl9, Cxcl10 and Socs1, but not Gadd45g. Our data demonstrate that allergen challenge induces two sets of Th1-associated genes in the lungs: 1) Ifng-dependent genes such as p47 and p65 GTPases, Socs1, Cxcl9 and Cxcl10 and 2) Ifng-independent Th1-inducing genes like Gadd45g. We propose that allergen-induced airway inflammation is regulated by simultaneous upregulation of Th1 and Th2 genes, and that persistent unopposed upregulation of Th1 genes resolves allergic inflammation.

Intranasal administration of CpG DNA lipoplex prevents pulmonary metastasis in mice

Synthetic oligodeoxynucleotides containing CpG motifs (CpG DNA) can activate immunocompetent cells which offer the potential advantage of antitumor activity. In this study, we used cationic liposomes to complex with CpG DNA (CpG DNA lipoplex) to prevent pulmonary metastasis following intranasal administration in mice. Intranasal administration of CpG DNA lipoplex prior to challenge with both colon26/Luc and B16F10 cells significantly prevented the proliferation of tumor cells, and the survival time of the mice receiving CpG DNA lipoplex was prolonged. After intranasal administration, [(32)P] CpG DNA lipoplex mainly distributed in nose and lung and induced higher IFN-gamma production in the lung. These results suggest that intranasal administration of CpG DNA lipoplex has a significant effect on preventing pulmonary metastasis in mice.

Differential kinase requirement for enhancement of Fc gammaR-mediated phagocytosis in alveolar macrophages by leukotriene B4 vs. D4

In alveolar macrophages, leukotriene (LT) B(4) and cysteinyl LTs (LTC(4), LTD(4) and LTE(4)) both enhance Fc gamma receptor (Fc gammaR)-mediated phagocytosis. In the present study we investigated the role of specific PKC isoforms (PKC-alpha and -delta), the MAP kinases p38 and ERK 1/2, and PI3K in mediating the potentiation of Fc gammaR-mediated phagocytosis induced by addition of leukotrienes to the AMs. It was found that exogenously added LTB(4) and LTD(4) both enhanced PKC-delta and -alpha phosphorylation during Fc gammaR engagement. Studies with isoform-selective inhibitors indicated that exogenous LTB(4) effects were dependent on both PKC-alpha and -delta, while LTD(4) effects were exclusively due to PKC-delta activation. Although both exogenous LTB(4) and LTD(4) enhanced p38 and ERK 1/2 activation, LTB(4) required only ERK 1/2, while LTD(4) required only p38 activation. Activation by both LTs was dependent on PI3K activation. Effects of endogenous LTs on kinase activation were also investigated using selective LT receptor antagonists. Endogenous LTB(4) contributed to Fc gammaR-mediated activation of PKC-alpha, ERK 1/2 and PI3K, while endogenous cysLTs contributes to activation of PKC-delta, p38 and PI3K. Taken together, our data show that the capacities of LTB(4) and LTD(4) to enhance Fc gammaR-mediated phagocytosis reflect their differential activation of specific kinase programs.

CpG-ODN inhibits airway inflammation at effector phase through down-regulation of antigen-specific Th2-cell migration into lung

Allergic airway inflammation is one of the most typical characteristic features of bronchial asthma. T(h)2 cells, which produce IL-4, IL-5 and IL-13, are well known as major effector lymphocytes of the inflammation. In the present work, we found that subcutaneous injection of Toll-like receptor-9-ligand, CpG-oligodeoxynucleotides (CpG-ODN), remarkably suppressed eosinophilia and mucus hyper-production in T(h)2 cell-dependent airway inflammation model at the effector phase. The injection of CpG-ODN significantly blocked T(h)2 cell migration into lung. The inhibitory effects of CpG-ODN were observed even when IFN-gamma-deficient T(h)2 cells were transferred into IFN-gamma(-/-) mice. In contrast, the administration of neutralizing mAbs against type I cytokines such as IFN-alpha, IFN-beta and IL-12 significantly suppressed the inhibitory effect of CpG-ODN on airway inflammation and T(h)2 cell migration into the lung. We further demonstrated that the production of T(h)2 chemokines, thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC), was significantly reduced by the CpG-ODN. The reduction of both TARC and MDC was also inhibited by the blockade of IFN-alpha, IFN-beta and IL-12 with mAbs. Thus, we revealed here that IFN-alpha, IFN-beta and IL-12, but not IFN-gamma, were required for the inhibitory effect of CpG-ODN in T(h)2 cell-mediated allergic airway inflammation. The present evidence strongly suggest that induction of type I cytokines would be promising therapeutic targets in T(h)2-dependent allergic diseases such as bronchial asthma.

A deficient TLR2 signaling promotes airway mucin production inMycoplasma pneumoniae-infected allergic mice

The original hygiene hypothesis suggests that early childhood respiratory infections preceding allergen exposure may decrease the prevalence of allergic diseases. We have recently demonstrated that Mycoplasma pneumoniae infection preceding allergen exposure reduced allergic responses in mice. However, the molecular mechanisms underlying the protective role of M. pneumoniae in allergic responses, particularly airway mucin production, remain unclear. Wild-type and Toll-like receptor 2 (TLR2)-deficient mice with a respiratory M. pneumoniae infection preceding allergen (ovalbumin) challenge were utilized to determine the regulatory role of TLR2-IFN-γ signaling pathway in airway mucin expression. Furthermore, air-liquid interface cultures of mouse primary tracheal epithelial cells were performed to examine the effects of IFN-γ on mucin expression. In wild-type mice, M. pneumoniae infection preceding allergen challenge significantly reduced airway mucins but increased IFN-γ. In sharp contrast, in TLR2-deficient mice, M. pneumoniae preceding allergen challenge resulted in increased mucin protein without a noticeable change of IFN-γ. In cultured mouse primary tracheal epithelial cells, IFN-γ was shown to directly inhibit mucin expression in a dose-dependent manner. Our study demonstrates for the first time that a respiratory M. pneumoniae infection preceding allergen challenge reduces airway epithelial mucin expression in part through TLR2-IFN-γ signaling pathway. A bacterial infection in asthmatic subjects with weakened TLR2-IFN-γ signaling may result in an exaggerated airway mucin production.

Oral sensitization to peanut is highly enhanced by application of peanut extracts to intact skin, but is prevented when CpG and cholera toxin are added

BACKGROUND

CpG oligonucleotides might offer an alternative to conventional immunotherapy in preventing and potentially reversing Th2-biased immune deregulation which leads to allergy. However, non-invasive ways of administration, especially in peanut-allergic patients, should be explored.

METHODS

One hundred micrograms of whole peanut protein extract (PE) alone, or mixed with cholera toxin (CT, 50 microg) plus CpG (100 microg) as adjuvant, was applied on intact skin of mice (40 min, twice). Initiation of an immune response was monitored by detection of specific antibodies in sera. The effect of this pretreatment on a further oral sensitization by PE was then evaluated by assaying antibodies and cytokines specific for PE and purified allergens. Cytokine production in liver 40 min after skin application was also assayed.

RESULTS

Two brief skin applications of PE alone highly potentiated further oral sensitization, as demonstrated by very intense specific IgE, IL-4 and IL-5 productions. Conversely, skin pretreatment with PE and CT + CpG efficiently prevented further sensitization via gastro-intestinal exposure. In both cases, the specificity of the antibodies and cytokines was the same as in control mice. CT + CpG treatment allowed the rapid production of IL-12 and TGFbeta in liver and of specific IgG2a in sera, suggesting the activation of Th1 and/or regulatory T cells.

CONCLUSIONS

Oral sensitization to peanut is highly enhanced by a previous short exposure of allergens to intact skin. Conversely, the use of CT + CpG adjuvant for skin application efficiently prevents further oral sensitization. The potential of such treatment in specific immunotherapy needs to be evaluated.

Enhancement of infectious disease vaccines through TLR9-dependent recognition of CpG DNA

The adaptive immune system-with its remarkable ability to generate antigen-specific antibodies and T lymphocytes against pathogens never before "seen" by an organism-is one of the marvels of evolution. However, to generate these responses, the adaptive immune system requires activation by the innate immune system. Toll-like receptors (TLRs) are perhaps the best-understood family of innate immune receptors for detecting infections and stimulating adaptive immune responses. TLR9 appears to have evolved to recognize infections by a subtle structural difference between eukaryotic and prokaryotic/viral DNA; only the former frequently methylates CpG dinucleotides. Used as vaccine adjuvants, synthetic oligodeoxynucleotide (ODN) ligands for TLR9--CpG ODN--greatly enhance the speed and strength of the immune responses to vaccination.

Distinct responses of lung and spleen dendritic cells to the TLR9 agonist CpG oligodeoxynucleotide

Dendritic cells (DCs) sense various components of invading pathogens via pattern recognition receptors such as TLRs. CpG oligodeoxynucleotides (ODNs), which mimic bacterial DNA, inhibit allergic airways disease and promote responses in the spleen to bacterial components. Because many TLR agonists are currently being tested for potential therapeutic effects, it is important to characterize the expression and function of TLRs in different tissues. We show that both myeloid and plasmacytoid DCs in the spleen express TLR9, the receptor for CpG ODNs, but lung DCs show no detectable expression in either subset. TLR4 expression in contrast was detected on both lung and spleen DCs. LPS was superior to CpG ODN in increasing the allostimulatory potential of lung DCs and their expression of CD40. However, both agonists efficiently stimulated spleen DCs. CpG ODNs administered to mice efficiently inhibited Th2 cytokine production both in the lung draining lymph node and in the spleen. Surprisingly, inhibition of Th2 cytokine production was evident despite high levels of expression of GATA-3 and additional transcription factors that regulate Th2 responses. Although in the spleen CpG ODNs induced IL-6, a key cytokine induced via TLR9-MyD88 signaling, no IL-6 was detectable in lung LN cells. These studies show for the first time that lung DCs lack TLR9 expression, but, despite this deficiency, CpG ODNs induce potent inhibitory effects on Th2 cytokine production in the lung without inducing expression of the proinflammatory cytokine, IL-6, which has been linked to chronic diseases in the lung and the gut.

Therapeutic potential of Toll-like receptor 9 activation

In the decade since the discovery that mouse B cells respond to certain unmethylated CpG dinucleotides in bacterial DNA, a specific receptor for these 'CpG motifs' has been identified, Toll-like receptor 9 (TLR9), and a new approach to immunotherapy has moved into the clinic based on the use of synthetic oligodeoxynucleotides (ODN) as TLR9 agonists. This review highlights the current understanding of the mechanism of action of these CpG ODN, and provides an overview of the preclinical data and early human clinical trial results using these drugs to improve vaccines and treat cancer, infectious disease and allergy/asthma.

Immunostimulatory oligonucleotides in therapy of allergic diseases

At present, the improvement of hygienic life standards is considered as an environmental condition, increasing the prevalence of allergic diseases, as early contact with some pathogens is, according to the hygiene hypothesis, required for maturation of the immune system. The recognition of microbial components involves acquired and innate immunity mechanisms. Recently, the link between innate and acquired immunity has been discovered. It involves the evolutionarily old Toll-like receptor (TLR) system. Ligands recognised by TLRs include unmethylated deoxycytidil-deoxyguanosine (CpG) motif-containing microbial DNA. TLR-mediated signalling induces expression of cytokines preferentially promoting a Th1-directed response. Therefore, synthetic CpG motif-containing immunostimulatory oligonucleotides could be employed in causal allergy treatment. This review discusses some molecular aspects of the TLR system, as well as results of animal studies and early experiences, including treatment safety, from human clinical trials with immunostimulatory CpG motif-containing oligonucleotides.

New aspects of p38 mitogen activated protein kinase (MAPK) biology in lung inflammation

Lung inflammation features in asthma, chronic obstructive airways disease (COPD), acute respiratory distress syndrome (ARDS), cystic fibrosis (CF) and others. Whilst in asthma anti-inflammatory glucocorticosteroids are generally effective, certain individuals are steroid resistant and in COPD, ARDS and CF, as well as disease exacerbations caused by infection, there seems little benefit. We summarise recent advances in p38 mitogen activated protein kinase (MAPK) biology and document beneficial and possibly detrimental effects in respect of lung inflammation.

Maria Belvisi – Imperial College School of Medicine, London, UK

Stuart Farrow – GlaxoSmithKline, Stevenage, UK

The Novel Cytokine p43 Induces IL-12 Production in Macrophages via NF-κB Activation, Leading to Enhanced IFN-γ Production in CD4+ T Cells

Recently, we determined that p43, an auxiliary factor of mammalian multiaminoacyl-tRNA synthetases, is secreted, and functions as a novel pleiotropic cytokine. In this study, we have attempted to characterize the effects of p43 on the generation of IL-12 in mouse macrophages. p43 was determined to induce significant IL-12 production from mouse macrophages in a dose-dependent manner. The stimulatory effect of p43 on the activation of IL-12p40 promoter was mapped to a region harboring an NF-kappaB binding site. The nuclear extracts from the p43-stimulated macrophages exhibited profound NF-kappaB DNA-binding activity, as determined by the EMSA. In addition, the p43-stimulated IL-12 induction and NF-kappaB DNA-binding activity were significantly suppressed by caffeic acid phenethyl ester and BAY11-7082, both inhibitors of NF-kappaB activation, indicating that p43 induced the production of IL-12 in macrophages mainly via the activation of NF-kappaB. Importantly, p43 increased the level of IFN-gamma production in the Ag-primed lymph node cells, but had no effect on IL-4 levels. The addition of a neutralizing anti-IL-12p40 mAb to the cell cultures resulted in a decrease of the production of p43-enhanced IFN-gamma by the keyhole limpet hemocyanin-primed lymph node cells. Furthermore, coincubation with p43-pretreated macrophages enhanced the production of IFN-gamma by the keyhole limpet hemocyanin-primed CD4+ T cells, thereby indicating that p43 may enhance IFN-gamma expression in CD4+ T cells via the induction of IL-12 production in macrophages. These results indicate that p43 may play an essential role in the development of the Th1 immune responses associated with cancer immunotherapy and protective immunity against intracellular pathogens.

p38 mitogen-activated protein kinase-dependent chemokine production, leukocyte recruitment, and hepatocellular apoptosis in endotoxemic liver injury

OBJECTIVE

To determine the role of p38 mitogen-activated protein kinase (MAPK) signaling in endotoxin-induced liver injury.

BACKGROUND

MAPKs have been reported to play a potential role in regulating inflammatory responses, but the role of p38 MAPK signaling in chemokine production, leukocyte recruitment, and hepatocellular apoptosis in the liver of endotoxemic mice is not known.

METHODS

Endotoxin-induced leukocyte-endothelium interactions were studied by use of intravital fluorescence microscopy in the mouse liver. Tumor necrosis factor-alpha (TNF-alpha) and CXC chemokines, liver enzymes, and apoptosis were determined 6 hours after endotoxin challenge. The specific p38 MAPK inhibitor SB 239063 was given immediately prior to endotoxin exposure. Phosphorylation and activity of p38 MAPK were determined by immunoprecipitation and Western blot.

RESULTS

Endotoxin increased phosphorylation and activity of p38 MAPK in the liver, which was markedly inhibited by SB 239063. Inhibition of p38 MAPK signaling dose-dependently decreased endotoxin-induced leukocyte rolling, adhesion, and sinusoidal sequestration of leukocytes. SB 239063 markedly reduced endotoxin-induced formation of TNF-alpha and CXC chemokines in the liver. Indeed, the endotoxin-provoked increase of liver enzymes and hepatocellular apoptosis were abolished and sinusoidal perfusion was restored in endotoxemic mice treated with SB 239063.

CONCLUSIONS

This study demonstrates that p38 MAPK signaling plays an important role in regulating TNF-alpha and CXC chemokine production in endotoxemic liver injury and that inhibition of p38 MAPK activity abolishes endotoxin-induced leukocyte infiltration as well as hepatocellular apoptosis. These novel findings suggest that interference with the p38 MAPK pathway may constitute a therapeutic strategy against septic liver damage.

ROS generated by pollen NADPH oxidase provide a signal that augments antigen-induced allergic airway inflammation

Pollen exposure induces allergic airway inflammation in sensitized subjects. The role of antigenic pollen proteins in the induction of allergic airway inflammation is well characterized, but the contribution of other constituents in pollen grains to this process is unknown. Here we show that pollen grains and their extracts contain intrinsic NADPH oxidases. The pollen NADPH oxidases rapidly increased the levels of ROS in lung epithelium as well as the amount of oxidized glutathione (GSSG) and 4-hydroxynonenal (4-HNE) in airway-lining fluid. These oxidases, as well as products of oxidative stress (such as GSSG and 4-HNE) generated by these enzymes, induced neutrophil recruitment to the airways independent of the adaptive immune response. Removal of pollen NADPH oxidase activity from the challenge material reduced antigen-induced allergic airway inflammation, the number of mucin-containing cells in airway epithelium, and antigen-specific IgE levels in sensitized mice. Furthermore, challenge with Amb a 1, the major antigen in ragweed pollen extract that does not possess NADPH oxidase activity, induced low-grade allergic airway inflammation. Addition of GSSG or 4-HNE to Amb a 1 challenge material boosted allergic airway inflammation. We propose that oxidative stress generated by pollen NADPH oxidases (signal 1) augments allergic airway inflammation induced by pollen antigen (signal 2).

Cytosine-phosphate-guanine motifs fail to promote T-helper type 1-polarized responses in human neonatal mononuclear cells

BACKGROUND

The T-helper type 1 (Th1) trophic properties of bacterial cytosine-phosphate-guanine (CpG) motifs have made them logical adjuvants both for the suppression of Th2-mediated allergic disease in early life and for promoting vaccine responses in neonates who have relatively immature Th1 function. However, little is known about their effects on immature immune responses in this period.

OBJECTIVES

To compare the effects of CpG on adult and neonatal cellular immune responses to various stimuli.

METHODS

The immune responses of mononuclear cells (MC) derived from neonates (n=25) and their mothers (n=25) were compared in vitro. These were stimulated with house dust mite (HDM), CpG B, CpG C, non-CpG oligodeoxynucleotides (ODN) or diphtheria toxoid (DT) in optimized conditions. In parallel cultures, CpGs were combined with HDM or DT antigens to assess the effect of the various ODN on these antigen-specific responses. Lymphoproliferation and cytokine responses IL-13, IFN-gamma, IL-6, IL-10, TNF-alpha) were measured for all of the cultures described above.

RESULTS

Although neonates showed attenuated lymphoproliferation to CpG, the production of antigen-presenting cell-derived cytokines such as IL-6 and IL-10 and the up-regulation of major histocompatibility complex class II (HLA-DR) were detected at adult levels. T cell-derived cytokines (IL-13 and IFN-gamma) were not detectable in response to CpG alone. Most neonates also failed to produce detectable IFN-gamma to HDM or DT (unlike adults), but readily produced IL-13 to these stimuli. The addition of CpG resulted in an increase in neonatal IFN-gamma production in response to HDM (P=0.011) and a similar but non-significant trend with DT. However, rather than inhibiting Th2 IL-13 responses, the addition of CpGs was associated with a significant increase in the IL-13 responses to HDM (P=0.016) and DT (P=0.03), effects not seen in adults.

CONCLUSIONS

This study provides further evidence that neonatal MC responses to CpG are functionally different from adults, and do not show clear Th1 polarization. The CpG associated increase in Th2 responses may reflect a potentiation of the normal neonatal Th2 propensity, or non-specific activation of neonatal MC.

Impaired toll-like receptor 9 expression in alveolar macrophages with no sensitivity to CpG DNA

Unmethylated CpG motifs in bacterial DNA or synthetic oligodeoxynucleotides (ODN) potently stimulate the innate immune system, and they are recognized by Toll-like receptor 9 (TLR9), which is expressed by monocytes/macrophages, dendritic cells, and B cells. However, it is unknown whether alveolar macrophages (AMs) express functional TLR9. To clarify this, we analyzed mRNA expressions of TLRs in murine AMs by real-time polymerase chain reaction, and compared with those in other tissue macrophages and lung antigen-presenting cells. In addition, we determined the sensitivity of these cell populations to CpG-ODN. Interestingly, TLR9 mRNA was almost absent in AMs, but highly expressed in bone marrow-derived macrophages and peritoneal macrophages, whereas TLR2 and TLR4 were present in all macrophage populations. Consistent with the receptor expression, AMs showed no sensitivity to CpG-ODN, whereas other macrophage populations secreted tumor necrosis factor alpha, interleukin 12 p40, and interleukin 6, and enhanced expression of CD40, CD80, and CD86, in response to CpG-ODN. Lung dendritic cells and B cells highly expressed TLR9 mRNA and responded to CpG-ODN. These results indicate selective loss of TLR9 expression in AMs with no sensitivity to CpG-ODN, suggesting that dendritic cells and B cells play a role in the immune response against bacterial DNA in the lung.

Fungal immunomodulatory protein from Flammulina velutipes induces interferon-gamma production through p38 mitogen-activated protein kinase signaling pathway

FIP-fve is a fungal immunomodulatory protein purified from Flammulina velutipes, an edible golden needle mushroom thought to possess potent immunomodulatory properties. When examined for its effects on lymphocytes, FIP-fve exhibited potent mitogenic effects on human peripheral blood lymphocytes, inducing G1/G0 to S phase proliferation. T cells activated by FIP-fve show significant production and secretion of interferon-gamma (IFN-gamma) associated with intercellular adhesion molecule 1 expression but low detectable levels of interleukin-4 in vitro or in vivo. However, SB203580, the p38 mitogen-activated protein kinase (p38 MAPK) inhibitor, can fully abolish the production of IFN-gamma induced by FIP-fve. At the same time, SB203580 only partially prevents the lymphocytes from progressing from G1 to S phase of the cell cycle. These findings demonstrate that FIP-fve is a potent T-cell activator, mediating its effects via cytokine regulation of p38 MAPK. The immunoprophylatic effects of FIP-fve in Th2-mediated allergic anaphylaxis are believed to be associated with the ability of FIP-fve to enhance activation of IFN-gamma-releasing Th1 cells.

Inhibitory oligonucleotides block the induction of AP-1 transcription factor by stimulatory CpG oligonucleotides in B cells

The proliferative response of primary B cells to CpG oligonucleotides (ODN) involves induction of nuclear activation promoting-1 (AP-1) transcription factor. AP-1 subunits c-Fos, Fos-B, Jun-B, and Jun-D, but not Fra-1 or Fra-2, were all induced by CpG ODNs in B cells within 30 minutes of stimulation, followed by c-Jun at 1-2 hours. c-Jun reached maximum at 6 hours. By 40 hours, Jun-B and Jun-D became dominant. Synthetic ODNs containing a single guanosine triplet/tetrad appropriately distanced from the 5' pyrimidine-rich unit, which inhibit CpG-driven cell cycle entry and apoptosis protection, blocked AP-1 induction by stimulatory ODNs when they were added simultaneously. After 30 minutes of stimulation, adding inhibitor no longer affected AP-1 at 6 hours. No AP-1 subunits escaped ODN inhibition. In a cell line transfected with an AP-1-beta-galactosidase reporter construct, CpG ODN-induced AP-1 transcriptional activity was prevented by inhibitory ODN, but lipopolysaccharide (LPS)-induced AP-1 activity was not. These data suggest that inhibitory ODNs block the CpG ODN-driven signaling pathway at a site proximal to AP-1 induction.

Extracellular regulated kinase/mitogen activated protein kinase is up-regulated in pulmonary emphysema and mediates matrix metalloproteinase-1 induction by cigarette smoke

The interstitial collagenase matrix metalloprotein-ase-1 (MMP-1) is up-regulated in the lung during pulmonary emphysema. The mechanisms underlying this aberrant expression are poorly understood. Although cigarette smoking is the predominant cause of emphysema, only 15-20% of smokers develop the disease. To define the signaling pathways activated by smoke and to identify molecules responsible for emphysema-associated MMP-1 expression, we performed several in vitro and in vivo experiments. In this study, we showed that cigarette smoke directly induced MMP-1 mRNA and protein expression and increased the collagenolytic activity of human airway cells. Treatment with various chemical kinase inhibitors revealed that this response was dependent on the extracellular regulated kinase-1/2 (ERK) mitogen activated protein kinase pathway. Cigarette smoke increased phosphorylation of residues Thr-202 and Tyr-204 of ERK in airway lining cells and alveolar macrophages in mice at 10 days and 6 months of exposure. Moreover, analysis of lung tissues from emphysema patients revealed significantly increased ERK activity compared with lungs of control subjects. This ERK activity was evident in airway lining and alveolar cells. The identification of active ERK in the lungs of emphysema patients and the finding that induction of MMP-1 by cigarette smoke in pulmonary epithelial cells is ERK-dependent reveal a molecular mechanism and potential therapeutic target for excessive matrix remodeling in smokers who develop emphysema.

A dinucleotide motif in oligonucleotides shows potent immunomodulatory activity and overrides species-specific recognition observed with CpG motif

Bacterial and synthetic DNAs containing CpG dinucleotides in specific sequence contexts activate the vertebrate immune system through Toll-like receptor 9 (TLR9). In the present study, we used a synthetic nucleoside with a bicyclic heterobase [1-(2'-deoxy-beta-d-ribofuranosyl)-2-oxo-7-deaza-8-methyl-purine; R] to replace the C in CpG, resulting in an RpG dinucleotide. The RpG dinucleotide was incorporated in mouse- and human-specific motifs in oligodeoxynucleotides (oligos) and 3'-3-linked oligos, referred to as immunomers. Oligos containing the RpG motif induced cytokine secretion in mouse spleen-cell cultures. Immunomers containing RpG dinucleotides showed activity in transfected-HEK293 cells stably expressing mouse TLR9, suggesting direct involvement of TLR9 in the recognition of RpG motif. In J774 macrophages, RpG motifs activated NF-kappa B and mitogen-activated protein kinase pathways. Immunomers containing the RpG dinucleotide induced high levels of IL-12 and IFN-gamma, but lower IL-6 in time- and concentration-dependent fashion in mouse spleen-cell cultures costimulated with IL-2. Importantly, immunomers containing GTRGTT and GARGTT motifs were recognized to a similar extent by both mouse and human immune systems. Additionally, both mouse- and human-specific RpG immunomers potently stimulated proliferation of peripheral blood mononuclear cells obtained from diverse vertebrate species, including monkey, pig, horse, sheep, goat, rat, and chicken. An immunomer containing GTRGTT motif prevented conalbumin-induced and ragweed allergen-induced allergic inflammation in mice. We show that a synthetic bicyclic nucleotide is recognized in the C position of a CpG dinucleotide by immune cells from diverse vertebrate species without bias for flanking sequences, suggesting a divergent nucleotide motif recognition pattern of TLR9.

CpG directly induces T-bet expression and inhibits IgG1 and IgE switching in B cells

CpG DNA has immunomodulatory effects, such as the suppression of allergic responses mediated by type II T cell help (T(H)2). Here we report that CpG, but not lipopolysaccharide (LPS), rapidly induces expression of T-bet mRNA in purified B cells. Up-regulation of T-bet by CpG is abrogated in mice deficient in Toll-like receptor 9 (TLR9) and MyD88, but remains intact in B cells deficient in STAT1 (signal transducer and activator of transcription 1). Interleukin 12 (IL-12) alone does not up-regulate T-bet mRNA, but greatly enhances CpG-induced T-bet expression. Furthermore, CpG inhibits immunoglobulin G1 (IgG1) and IgE switching induced by IL-4 and CD40 signaling in purified B cells, and this effect correlates with up-regulation of T-bet. Thus, CpG triggers anti-allergic immune responses by directly regulating T-bet expression via a signaling pathway in B cells that is dependent upon TLR9, independent of interferon-gamma (IFN-gamma)-STAT1 and synergistic with IL-12.

Induction of interleukin-12 production in mouse macrophages by berberine, a benzodioxoloquinolizine alkaloid, deviates CD4+ T cells from a Th2 to a Th1 response

In this study we investigated whether berberine-mediated induction of interleukin-12 (IL-12) production in antigen-presenting cells could regulate a cytokine profile of antigen-primed CD4+ T helper (Th) cells. Pretreatment with berberine induced IL-12 production in both macrophages and dendritic cells, and significantly increased the levels of IL-12 production in lipopolysaccharide-stimulated macrophages and in CD40 ligand-stimulated dendritic cells. Importantly, berberine pretreatment of macrophages increased their ability to induce interferon-gamma (IFN-gamma) and reduced their ability to induce IL-4 in antigen-primed CD4+ T cells. Berberine did not influence the macrophage cell surface expression of the class II major histocompatibility complex molecule, the co-stimulatory molecules CD80 and CD86, and intracellular adhesion molecule-1. Addition of neutralizing anti-IL-12p40 monoclonal antibody to cultures of berberine-pretreated macrophages and CD4+ T cells restored IL-4 production in antigen-primed CD4+ T cells. The in vivo administration of berberine resulted in the enhanced induction of IL-12 production by macrophages when stimulated in vitro with lipopolysaccharide or heat-killed Listeria monocytogenes, leading to the inhibition of the Th type 2 cytokine profile (decreased IL-4 and increased IFN-gamma production) in antigen-primed CD4+ T cells. These findings may point to a possible therapeutic use of berberine or medicinal plants containing berberine in the Th type 2 cell-mediated immune diseases such as allergic diseases.

Divergent synthetic nucleotide motif recognition pattern: design and development of potent immunomodulatory oligodeoxyribonucleotide agents with distinct cytokine induction profiles

Unmethylated CpG dinucleotides present within certain specific sequence contexts in bacterial and synthetic DNA stimulate innate immune responses and induce cytokine secretion. Recently, we showed that CpG DNAs containing two 5'-ends, immunomers, are more potent in both regards. In this study, we show that an immunomer containing a synthetic CpR motif (R = 2'-deoxy-7-deazaguanosine) is a potent immunostimulatory agent. However, the profile of cytokine induction is different from that with immunomers containing a natural CpG motif. In general, a CpR immunomer induced higher interleukin (IL)-12 and lower IL-6 secretion. Compared with conventional CpG DNAs, both types of immunomers showed a rapid and enhanced activation of the transcription factor NF-kappaB in J774 cells. NF-kappaB activation by CpG DNA corresponded to degradation of IkappaBalpha in J774 cells. All three immunostimulatory oligonucleotides activated the p38 mitogen-activated protein kinase pathway as expected. Immunomers containing CpG and CpR motifs showed potent reversal of the antigen-induced Th2 immune response towards a Th1 type in antigen-sensitized mouse spleen cell cultures. Immunomers containing a CpR motif showed significant antitumor activity in nude mice bearing MCF-7 human breast cancer and U87MG glioblastoma xenografts. These studies suggest the ability for a divergent synthetic nucleotide motif recognition pattern of the receptor involved in the immunostimulatory pathway and the possibility of using synthetic nucleotides to elicit different cytokine response patterns.