Immunologic basis of antigen-induced airway hyperresponsiveness

Pseudotyped adeno-associated virus 2/9-delivered CCL11 shRNA alleviates lung inflammation in an allergen-sensitized mouse model

Airway infiltration by eosinophils is a major characteristic of chronic asthma. CCL11 (eotaxin-1) is secreted by lung epithelial cells and functions as the major chemokine for eosinophil recruitment. Pseudotyped adeno-associated virus (AAV) 2/9, composed by the AAV2 rep and AAV9 cap genes, can efficiently target lung epithelial cells and might carry gene sequences with therapeutic potential for asthma. This study aimed to determine whether pseudotyped AAV2/9 virus carrying the small hairpin RNA targeting CCL11 and expressed by CMV/U6 promoter could reduce eosinophilia and asthmatic responses in mite allergen-sensitized mice. Mice were sensitized by intraperitoneal and challenged by intratracheal injection with recombinant Dermatophagoides pteronyssinus group 2 allergen (rDp2). AAV2/9 viral vectors were intratracheally injected three days before the first challenge. AAV2/9 sh47 virus significantly reduced airway hyperresponsiveness, airway resistance, CCL11 levels, and eosinophilia in the lungs of sensitized mice. Th2 cytokines, including interleukins (IL)-4, IL-5, and IL-10, were also significantly reduced in the bronchoalveolar lavage fluid of AAV2/9 sh47 virus-treated mice. Th2 cytokine levels were also reduced in rDp2-stimulated mediastinal lymphocytes in treated mice. However, serum levels of rDp2-specific IgG1 and IgE, as well as Th2 cytokine levels in rDp2-stimulated splenocyte culture supernatants, were comparable to the sensitized control group. The results suggest that AAV2/9 sh47 virus relieved local instead of systemic inflammatory responses. Therefore, the CMV/U6 promoter with AAV2/9 viral vector, which is preferable to target lung epithelia cells, might be applied as a novel therapeutic approach for asthma.

IL-4 inhibits TNF-α-mediated osteoclast formation by inhibition of RANKL expression in TNF-α-activated stromal cells and direct inhibition of TNF-α-activated osteoclast precursors via a T-cell-independent mechanism in vivo

It has been reported that osteoclastogenesis is induced by tumor necrosis factor (TNF)-α. Interleukin (IL)-4 is the most important cytokine involved in humoral immunity. However, no studies have investigated the effect of IL-4 on TNF-α-mediated osteoclast formation in vivo. In this study, we investigated the effect of IL-4 on TNF-α-mediated osteoclast formation in vivo. TNF-α was administered with and without IL-4 into the supracalvariae of mice. The number of osteoclasts and the levels of mRNA for cathepsin K and tartrate-resistant acid phosphate, both osteoclast markers, in mice administered TNF-α and IL-4 were lower than those in mice administered TNF-α alone. The level of tartrate-resistant acid phosphatase form 5b (TRACP5b) as a marker of bone resorption in mice administered both TNF-α and IL-4 was also lower. We showed that IL-4 inhibited TNF-α-mediated osteoclast formation in osteoclast precursors in vitro. Expression of receptor activator of NF-κB ligand (RANKL) in TNF-α-activated stromal cells was also inhibited. Furthermore, we investigated whether IL-4 had effects on both stromal cells and osteoclast precursors in TNF-α-mediated osteoclast formation in vivo. Using mice whose stromal cells and osteoclast precursors were chimeric for the presence of TNF receptors, IL-4 inhibited TNF-α-mediated osteoclast formation in the presence of TNF-α-responsive stromal cells, and TNF-α-responsive osteoclast precursors in vivo. IL-4 also inhibited TNF-α-induced RANKL expression in the presence of TNF-α-responsive stromal cells in vivo. This event is dependent on p38 inhibition in vitro. Additionally, IL-4 inhibited TNF-α-mediated osteoclast formation in T cell-depleted mice. In summary, we conclude that IL-4 inhibited TNF-α-mediated osteoclast formation by inhibiting expression of RANKL in TNF-α-activated stromal cells, and directly inhibited TNF-α-activated osteoclast precursors in vivo via a T cell-independent mechanism.

Biphasic late airway hyperresponsiveness in a murine model of asthma

BACKGROUND

Nonspecific airway hyperresponsiveness (AHR) is one of the cardinal features of bronchial asthma. Early AHR is caused by chemical mediators released from pulmonary mast cells activated in an IgE-dependent way. However, the mechanism of late AHR remains unclear.

METHODS

Features of airway allergic inflammation were analyzed, including antigen-induced AHR, using a murine model of asthma. The model was suitable for examining the sequential early molecular events occurring after the initial airway exposure to antigen.

RESULTS

AHR increased at 10-12 h after airway challenge, followed by the second-phase response, which was larger and broader in resistance at 18-30 h. Pretreatment of sensitized animals with anti-tumor necrosis factor (TNF) before airway challenge or induction of allergic asthma in TNF(-/-) mice resulted in abrogation of the first-phase late AHR. Intratracheal instillation of TNF induced a single peak of AHR at 10 h. IgE and IgG immune complexes induced the development of the first-phase late AHR by TNF production. Pretreatment with cytosolic phospholipase inhibitor and 5-lipoxygenase inhibitors abolished the first-phase late AHR as well as the leukotriene B(4) levels in the airway. CpG-oligodeoxynucleotide (ODN) pretreatment reduced airway levels of Th2 cytokines, eosinophil infiltration and second-phase late AHR. However, CpG-ODN did not reduce TNF levels or the magnitude of first-phase late AHR.

CONCLUSION

Biphasic late AHR occurs in a murine model of asthma. First- and second-phase late AHR is caused by TNF and Th2 response, respectively.

Antiallergic asthma properties of brazilin through inhibition of TH2 responses in T cells and in a murine model of asthma

This study aimed to determine whether brazilin exhibits anti-inflammatory effects that inhibit T helper cell type II (T(H)2) responses and whether it suppresses allergic inflammation reactions in a murine model of asthma. We found that brazilin inhibited the mRNA and protein expression of interleukin (IL)-4 and IL-5 induced by phorbol myristate acetate (PMA) and cAMP in EL-4 T cells in a dose-dependent manner. Following the intratracheal instillation of brazilin in ovalbumin (OVA)-immunized mice, we found that brazilin-treated mice exhibited decreases in the release of IL-4, IL-5, IL-13, eotaxin-1, and tumor necrosis factor-α in bronchoalveolar lavage fluid (BALF); inhibited T(H)2 functioning via a decrease in IL-4 production; and exhibited attenuation of OVA-induced lung eosinophilia, airway hyperresponsiveness, and airway remodeling. These results suggest that brazilin exhibits anti-T(H)2 effects both in vitro and in vivo and may possess therapeutic potential for allergic diseases.

CD11c+ cells are required for antigen-induced increase of mast cells in the lung

Patients with allergic asthma have more lung mast cells, which likely worsens the symptoms. In experimental asthma, CD11c(+) cells have to be present during the challenge phase for several features of allergic inflammation to occur. Whether CD11c(+) cells play a role for Ag-induced increases of lung mast cells is unknown. In this study, we used diphtheria toxin treatment of sensitized CD11c-diphtheria toxin receptor transgenic mice to deplete CD11c(+) cells. We demonstrate that recruitment of mast cell progenitors to the lung is substantially reduced when CD11c(+) cells are depleted during the challenge phase. This correlated with an impaired induction of endothelial VCAM-1 and led to a significantly reduced number of mature mast cells 1 wk after challenge. Collectively, these data suggest that Ag challenge stimulates CD11c(+) cells to produce cytokines and/or chemokines required for VCAM-1 upregulation on the lung endothelium, which in turn is crucial for the Ag-induced mast cell progenitor recruitment and the increase in mast cell numbers.

CX3CL1 in allergic diseases: not just a chemotactic molecule

Allergic asthma and atopic dermatitis (AD) are two allergic diseases that are primarily driven by the activation of T helper (Th)2 cells. Th2 cells produce cytokines that directly contribute to the symptoms of these diseases. The recruitment and maintenance of Th2 cells into the target tissues are two key events in the pathogenesis of allergic asthma and AD. While migration is mediated by both chemokines and lipid mediators such as leukotrienes and prostaglandins, very little is known about the molecules involved in lymphocyte survival and maintenance in inflamed tissues. However, chemokines could also play a role in this phenomenon. An example of this could be illustrated by CX3CL1, also known as fractalkine. CX3CL1 is a chemokine that is upregulated in some inflammatory diseases including allergic pathologies and that was recently demonstrated to provide a survival signal upon binding to its unique receptor CX3CR1.

Epithelial cell-derived IL-25, but not Th17 cell-derived IL-17 or IL-17F, is crucial for murine asthma

IL-17A, IL-17F, and IL-25 are ligands for IL-17RA. In the current study, we demonstrated that IL-25-deficient mice-but not IL-17A-, IL-17F-, IL-17A/F-, IL-23p19-, or retinoic acid-related orphan receptor (ROR)-γt-deficient mice-showed significant suppression of 1) the number of eosinophils and the levels of proinflammatory mediators in bronchoalveolar lavage fluids, 2) airway hyperresponsiveness to methacholine, and 3) OVA-specific IgG1 and IgE levels in the serum during OVA-induced Th2-type/eosinophilic airway inflammation. The IL-25 deficiency did not affect lung dendritic cell migration or Ag-specific memory-Th2 cell expansion during Ag sensitization. Adoptive transfer of T cells, mast cells, or bone marrow cells from IL-25-deficient mice revealed that induction of Th2-type/eosinophilic airway inflammation was dependent on activation of lung epithelial cells and eosinophils by IL-25 produced by airway structural cells such as epithelial cells but not by such hematopoietic stem-cell-origin immune cells as T cells and mast cells. Therefore, airway structural cell-derived IL-25-rather than Th17 cell-derived IL-17A and IL-17F-is responsible for induction of local inflammation by promoting activation of lung epithelial cells and eosinophils in the elicitation phase of Th2-type/eosinophilic airway inflammation. It is not required for Ag-specific Th2 cell differentiation in the sensitization phase.

Food-induced anaphylaxis: mast cells as modulators of anaphylactic severity

A food-induced anaphylactic reaction can occur within seconds to a few hours following exposure to the causal food allergen and often affects multiple organ systems including gastrointestinal, cutaneous, respiratory, and cardiovascular. A conundrum in the allergy field is that consumption of the same allergen can cause reactions of vastly different severity in separate individuals; one patient may experience a mild non-life-threatening reaction characterized by pruritis of lips or urticaria whereas another may experience a life-threatening reaction that involves respiratory and cardiovascular compromise leading to loss of consciousness and sometimes death. While there are tests available to determine the predictive risk value of a positive food challenge test or clinical reactivity, there is currently no reliable method to distinguish between individuals who are at risk of mild non-life-threatening versus life-threatening reaction. Recent research has significantly advanced our understanding of the involvement of immune pathways in the effector phase of food-induced anaphylaxis; a void remains regarding our understanding of the contribution of these pathways to severity of disease. In this review, we discuss mild non-life-threatening versus life-threatening food-induced anaphylaxis and factors (co-morbidities and immune activation) that predispose individuals to more severe disease. Furthermore, we summarize recent advancements in our understanding of the involvement of underlying immune pathways in systemic and food-induced anaphylaxis in mouse systems and discuss how these pathways may contribute to more severe disease phenotype.

Bronchial hyperresponsiveness in seasonal allergic rhinitis patients is associated with increased IL-18 during natural pollen exposure

BACKGROUND

The mechanism of bronchial hyperresponsiveness (BHR) is not certain in seasonal allergic rhinitis (SAR) patients.

OBJECTIVE

We aimed to investigate the effects of natural pollen exposure on IL-18 and its relationship with BHR.

METHODS

Thirty-two SAR patients with grass pollen sensitivity, 14 nonallergic rhinitis (NAR) patients and 17 normal-controls were included. Sixteen SAR patients had BHR during pollen season and off-season. Serum IL-18 levels were measured in SAR patients during pollen season between May-August and off-season between November-February. IL-18 levels were measured in NAR patients and normal controls once.

RESULTS

During pollen season, SAR patients with BHR had significantly increased levels of IL-18 than those without BHR (279.2 ± 161.1 versus 145.3 ± 101.0 pg/ml, p=0.012). Serum IL-18 levels were not different between SAR patients with and without BHR during off-season (233.8 ± 139.7 versus 183.2 ± 162.9 pg/ml, p=0.16). Serum IL-18 levels in SAR patients during pollen season (212.3 ± 148.8 pg/ml) and off-season (208.5 ± 151.5 pg/ml) were not different than those NAR patients (224.8 ± 180.1 pg/ml, p=0.98 and p=1.0, respectively) and normal controls (174.8 ± 76.0 pg/ml, p=0.60 and p=0.76, respectively).

CONCLUSION

The results suggested us that BHR in SAR patients is associated with increased IL-18 during natural pollen exposure.

Sitagliptin exerts anti-inflammatory and anti-allergic effects in ovalbumin-induced murine model of allergic airway disease

Sitagliptin, a new oral glucose lowering medication, is used for treatment of type 2 diabetes mellitus. The anti-inflammatory property of sitagliptin is reported, yet no studies have been done on asthma. In the present study, the effect of sitagliptin on allergic asthma was investigated using ovalbumin (OVA)-induced asthma model in mice. Swiss male albino mice sensitized and challenged to ovalbumin were treated with sitagliptin (8 mg/kg administered orally twice a day). Drug treatment was done on each day from days 16 to 23, 1 h before the challenge on the days of challenge. Sitagliptin treatment markedly decreased inflammatory cell accumulation in bronchoalveolar lavage (BAL) fluid and in the lungs, as revealed by histopathological examination. Furthermore, the levels of interleukin (IL)-13 in BAL fluid, total and OVA specific immunoglobulins (Ig)-E in serum, were significantly reduced as compared to the OVA group. In addition, sitagliptin significantly increased superoxidase dismutase (SOD) and reduced glutathione (GSH) activities with significant decrease in malondialdehyde (MDA) content in the lung. Importantly, sitagliptin decreased mRNA expression of the inflammatory cytokines tumor necrosis factor-α (TNF-α) and transforming growth factor-β(1) (TGF-β(1)) in lung tissues as compared to the OVA group. Moreover, nitric oxide content as well as the mRNA expression of inducible nitric oxide synthase (iNOS) was remarkably decreased by sitagliptin treatment. Sitagliptin attenuates the allergic airway inflammation suggesting that sitagliptin may have applications in the treatment of bronchial asthma.

Interleukin-13 peptide kinoid vaccination attenuates allergic inflammation in a mouse model of asthma

Asthma is an atopic disorder with increasing frequency and severity in developed nations. Interleukin-13 (IL-13) is one of the most critical mediators of asthma pathology. In the present study, we developed a vaccine comprised of a keyhole limpet hemocyanin-mIL-13 heterocomplex immunogen to persistently neutralize excessive endogenous IL-13. Our results showed that the IL-13 peptide kinoid vaccine could induce sustained and high titer of IL-13-specific IgG when using aluminum hydroxide as an adjuvant, and could suppress the accumulation of eosinophils as well as IL-13 levels in bronchoalveolar lavage fluid (BALF). In addition, total IgE and ovalbumin (OVA)-specific IgE in serum were significantly inhibited. This study also showed that vaccination could prevent airway inflammation and epithelial cell proliferation with goblet cell hyperplasia in a mouse model of acute asthma. In summary, our findings suggest that the IL-13 peptide kinoid can serve as an innovative and effective vaccine against asthma.

Electroacupuncture Attenuates Ovalbumin-Induced Allergic Asthma via Modulating CD4(+)CD25(+) Regulatory T Cells

A mouse pulmonary hypersensitivity experimental model that mimics human asthma was developed, and electroacupuncture (EA) treatment was shown to reduce allergic inflammatory processes. In addition, we also assessed whether the beneficial effects of EA on allergic asthma could be correlated with CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg). Cellular profiles and histopathologic analysis demonstrated that peribronchial and perivascular inflammatory cell infiltrates were significantly decreased in the EA-treated groups when compared to the OVA and anti-CD25 Ab-injected (Treg depletion) groups. Furthermore, total BAL cells were reduced in the EA groups when compared to other groups. Interestingly, the population of CD4(+)CD25(+)Foxp3(+)Tregs in pneumonocytes increased in EA-treated group when compared to OVA and Treg depletion groups. These results imply that EA stimulation at ST 36 may affect CD4(+)CD25(+)Foxp3(+) Treg in an OVA-induced experimental model and may enhance Treg function by suppressing other T cells and limiting the immune response.

Complement C3a-induced IL-17 plays a critical role in an IgE-mediated late-phase asthmatic response and airway hyperresponsiveness via neutrophilic inflammation in mice

Allergen-specific IgE plays an essential role in the pathogenesis of allergic asthma. Although there has been increasing evidence suggesting the involvement of IL-17 in the disease, the relationship between IL-17 and IgE-mediated asthmatic responses has not yet been defined. In this study, we attempted to elucidate the contribution of IL-17 to an IgE-mediated late-phase asthmatic response and airway hyperresponsiveness (AHR). BALB/c mice passively sensitized with an OVA-specific IgE mAb were challenged with OVA intratracheally four times. The fourth challenge caused a late-phase increase in airway resistance associated with elevated levels of IL-17(+)CD4(+) cells in the lungs. Multiple treatments with a C3a receptor antagonist or anti-C3a mAb during the challenges inhibited the increase in IL-17(+)CD4(+) cells. Meanwhile, a single treatment with the antagonist or the mAb at the fourth challenge suppressed the late-phase increase in airway resistance, AHR, and infiltration by neutrophils in bronchoalveolar lavage fluid. Because IL-17 production in the lungs was significantly repressed by both treatments, the effect of an anti-IL-17 mAb was examined. The late-phase increase in airway resistance, AHR, and infiltration by neutrophils in bronchoalveolar lavage fluid was inhibited. Furthermore, an anti-Gr-1 mAb had a similar effect. Collectively, we found that IgE mediated the increase of IL-17(+)CD4(+) cells in the lungs caused by repeated Ag challenges via C3a. The mechanisms leading to the IgE-mediated late-phase asthmatic response and AHR are closely associated with neutrophilic inflammation through the production of IL-17 induced by C3a.

The translational repressor T-cell intracellular antigen-1 (TIA-1) is a key modulator of Th2 and Th17 responses driving pulmonary inflammation induced by exposure to house dust mite

T-cell intracellular antigen-1 (TIA-1) is a translational repressor that dampens the production of proinflammatory cytokines and enzymes. In this study we investigated the role of TIA-1 in a mouse model of pulmonary inflammation induced by exposure to the allergenic extract (Df) of the house dust mite Dermatophagoides farinae. When intranasally challenged with a low dose of Df, mice lacking TIA-1 protein (Tia-1(-/-)) showed more severe airway and tissue eosinophilia, infiltration of lung bronchovascular bundles, and goblet cell metaplasia than wild-type littermates. Tia-1(-/-) mice also had higher levels of Df-specific IgE and IgG(1) in serum and ex vivo restimulated Tia-1(-/-) lymph node cells and splenocytes transcribed and released more Th2/Th17 cytokines. To evaluate the site of action of TIA-1, we studied the response to Df in bone marrow chimeras. These experiments revealed that TIA-1 acts on both hematopoietic and non-hematopoietic cells to dampen pulmonary inflammation. Our results identify TIA-1 as a negative regulator of allergen-mediated pulmonary inflammation in vivo. Thus, TIA-1 might be an important player in the pathogenesis of bronchial asthma.

Dynamic role of epithelium-derived cytokines in asthma

Asthma is an inflammatory disorder of the airways, characterized by infiltration of mast cells, eosinophils, and Th2-type CD4+ T cells in the airway wall. Airway epithelium constitutes the first line of interaction with our atmospheric environment. The protective barrier function of the airway epithelium is likely impaired in asthma. Furthermore, recent studies suggest critical immunogenic and immunomodulatory functions of airway epithelium. In particular, a triad of cytokines, including IL-25, IL-33 and TSLP, is produced and released by airway epithelial cells in response to various environmental and microbial stimuli or by cellular damage. These cytokines induce and promote Th2-type airway inflammation and cause remodeling and pathological changes in the airway walls, suggesting their pivotal roles in the pathophysiology of asthma. Thus, the airway epithelium can no longer be regarded as a mere structural barrier, but must be considered an active player in the pathogenesis of asthma and other allergic disorders.

Intestinal mast cell levels control severity of oral antigen-induced anaphylaxis in mice

Food-triggered anaphylaxis can encompass a variety of symptoms that affect multiple organ systems and can be life threatening. The molecular distinction between non-life-threatening and life-threatening modes of such anaphylaxis has not yet been delineated. In this study, we sought to identify the specific immune functions that regulate the severity of oral antigen-induced anaphylaxis. We thus developed an experimental mouse model in which repeated oral challenge of ovalbumin-primed mice induced an FcεRI- and IgE-dependent oral antigen-triggered anaphylaxis that involved multiple organ systems. Strikingly, the severity of the systemic symptoms of anaphylaxis (eg, hypothermia) positively correlated with the levels of intestinal mast cells (r = -0.53; P < 0.009). In addition, transgenic mice with both increased intestinal and normal systemic levels of mast cells showed increased severity of both intestinal and extra-intestinal symptoms of IgE-mediated passive as well as oral antigen- and IgE-triggered anaphylaxis. In conclusion, these observations indicate that the density of intestinal mast cells controls the severity of oral antigen-induced anaphylaxis. Thus, an awareness of intestinal mast cell levels in patients with food allergies may aid in determining their susceptibility to life-threatening anaphylaxis and may eventually aid in the treatment of food-triggered anaphylaxis.

T helper 17 cells and regulatory T-cell imbalance in paediatric patients with asthma

Asthma is a chronic inflammatory disorder of the lung, which is thought to be determined by the balance between the T helper (Th)2 and Th1 responses. This study evaluated whether the balance between Th17 cells and regulatory T cells (T(reg)) was impaired in asthma patients. The proportion of peripheral blood Th17 cells of the total CD4(+) cell population in asthma patients was significantly higher than in controls (mean ± SD 0.72 ± 0.5% versus 0.31 ± 0.4%, respectively). The proportion of peripheral T(reg) cells in asthma patients was significantly lower than in controls (mean ± SD 12.1 ± 4.6% versus 27.2 ± 7.5%, respectively). Analysis of mRNA generally confirmed the flow cytometry data, suggesting that the changes in cytokine levels were mediated at the transcription level. In paediatric asthma patients, the CD4(+) T-cell phenotype was skewed toward the Th17 phenotype, suggesting that a Th17/T(reg) functional imbalance plays a role in asthma.

Structural and functional characterization of a novel nonglycosidic type I NKT agonist with immunomodulatory properties

Activation of type I NKT (iNKT) cells by CD1d-presented agonists is a potent immunotherapeutic tool. α-Galactosylceramide (α-GalCer) is the prototypic agonist, but its excessive potency with simultaneous production of both pro- and anti-inflammatory cytokines hampers its potential therapeutic use. In search for novel agonists, we have analyzed the structure and function of HS44, a synthetic aminocyclitolic ceramide analog designed to avoid unrestrained iNKT cell activation. HS44 is a weaker agonist compared with α-GalCer in vitro, although in vivo it induces robust IFN-γ production, and highly reduced but still functional Th2 response. The characteristic cytokine storm produced upon α-GalCer activation was not induced. Consequently, HS44 induced a very efficient iNKT cell-dependent antitumoral response in B16 animal model. In addition, intranasal administration showed the capacity to induce lung inflammation and airway hyperreactivity, a cardinal asthma feature. Thus, HS44 is able to elicit functional Th1 or Th2 responses. Structural studies show that HS44 binds to CD1d with the same conformation as α-GalCer. The TCR binds to HS44 similarly as α-GalCer, but forms less contacts, thus explaining its weaker TCR affinity and, consequently, its weaker recognition by iNKT cells. The ability of this compound to activate an efficient, but not massive, tailored functional immune response makes it an attractive reagent for immune manipulation.

Inflammasome-IL-1-Th17 response in allergic lung inflammation

Allergic asthma has increased dramatically in prevalence and severity over the last three decades. Both clinical and experimental data support an important role of Th2 cell response in the allergic response. Recent investigations revealed that airway exposure to allergen in sensitized individuals causes the release of ATP and uric acid, activating the NLRP3 inflammasome complex and cleaving pro-IL-1β to mature IL-1β through caspase-1. The production of pro-IL-1β requires a toll-like receptor (TLR) 4 signal which is provided by the allergen. IL-1β creates a pro-inflammatory milieu with the production of IL-6 and chemokines which mobilize neutrophils and enhance Th17 cell differentiation in the lung. Here, we review our results showing that NLRP3 inflammasome activation is required to develop allergic airway inflammation in mice and that IL-17 and IL-22 production by Th17 cells plays a critical role in established asthma. Therefore, inflammasome activation leading to IL-1β production contributes to the control of allergic asthma by enhancing Th17 cell differentiation.

Allergen-specific CTL require perforin expression to suppress allergic airway inflammation

Allergen-specific CTL have a protective effect on allergic airway inflammation, a function thought to be mediated by cytokines, especially IFN-γ. However, the contribution of cytotoxic function to this protective effect has not been investigated. We examined the contribution of cytotoxic function to the therapeutic effect of allergen-specific CTL in allergic airway inflammation. We used a murine model of allergic airway inflammation in which mice were sensitized to OVA and then challenged with the same Ag via the intranasal route. CTL were elicited in these mice by immunization with dendritic cells (DC) or by adoptive transfer of in vitro-activated CD8(+) T cells. Hallmark features of allergic asthma, such as infiltration of eosinophils in the bronchoalveolar lavage fluid and mucus production, were assessed. Suppression of allergic airway inflammation by allergen-specific CTL was critically dependent on the expression of perforin, a key component of the cytotoxic machinery. Both perforin-sufficient and perforin-deficient allergen-specific CTL were recovered from the lungs of allergen-sensitized mice and upregulated CD69 expression and secreted the cytokines IFN-γ and TNF-α upon intranasal allergen challenge. However, only perforin-sufficient CTL inhibited eosinophil infiltration in the airway, mucus production, and cytokine accumulation in the bronchoalveolar lavage fluid. Treatment with allergen-specific CTL, but not their perforin-deficient counterparts, was also associated with a decrease in the number of DC in the mediastinal lymph node. Our data suggest that the cytotoxic function of allergen-specific CD8(+) T cells is critical to their ability to moderate allergic airway inflammation.

Resistin-like molecule-α regulates IL-13-induced chemokine production but not allergen-induced airway responses

Resistin-like molecule α (Relm-α) is one of the most up-regulated gene products in allergen- and parasite-associated Th2 responses. Localized to alternatively activated macrophages, Relm-α was shown to exert an anti-inflammatory effect in parasite-induced Th2 responses, but its role in experimental asthma remains unexplored. Here, we analyzed the cellular source, the IL-4 receptors required to stimulate Relm-α production, and the role of Relm-α after experimental asthma induction by IL-4, IL-13, or multiple experimental regimes, including ovalbumin and Aspergillus fumigatus immunization. We demonstrate that Relm-α was secreted into the airway lumen, dependent on both the IL-13 receptor-α1 chain and likely the Type I IL-4 receptor, and differentially localized to epithelial cells and myeloid cells, depending on the specific cytokine or aeroallergen trigger. Studies performed with Retnla gene-targeted mice demonstrate that Relm-α was largely redundant in terms of inducing the infiltration of Th2 cytokines, mucus, and inflammatory cells into the lung. These results mirror the dispensable role that other alternatively activated macrophage products (such as arginase 1) have in allergen-induced experimental asthma and contrast with their role in the setting of parasitic infections. Taken together, our findings demonstrate the distinct utilization of IL-4/IL-13 receptors for the induction of Relm-α in the lungs. The differential regulation of Relm-α expression is likely determined by the relative expression levels of IL-4, IL-13, and their corresponding receptors, which are differentially expressed by divergent cells (i.e., epithelial cells and macrophages.) Finally, we identify a largely redundant functional role for Relm-α in acute experimental models of allergen-associated Th2 immune responses.

Anti-inflammatory effects of Tat-Annexin protein on ovalbumin-induced airway inflammation in a mouse model of asthma

Chronic airway inflammation is a key feature of bronchial asthma. Annexin-1 (ANX1) is an anti-inflammatory protein that is an important modulator and plays a key role in inflammation. Although the precise action of ANX1 remains unclear, it has emerged as a potential drug target for inflammatory diseases such as asthma. To examine the protective effects of ANX1 protein on ovalbumin (OVA)-induced asthma in animal models, we used a cell-permeable Tat-ANX1 protein. Mice sensitized and challenged with OVA antigen had an increased amount of cytokines and eosinophils in their bronchoalveolar lavage (BAL) fluid. However, administration of Tat-ANX1 protein before OVA challenge significantly decreased the levels of cytokines (interleukin (IL)-4, IL-5, and IL-13) and BAL fluid in lung tissues. Furthermore, OVA significantly increased the activation of mitogen-activated protein kinase (MAPK) in lung tissues, whereas Tat-ANX1 protein markedly reduced phosphorylation of MAPKs such as extracellular signal-regulated protein kinase, p38, and stress-activated protein kinase/c-Jun N-terminal kinase. These results suggest that transduced Tat-ANX1 protein may be a potential protein therapeutic agent for the treatment of lung disorders including asthma.

The potential role of interleukin-17 in severe asthma

Asthma has long been characterized as a disease of dysregulated T-helper type 2 immune responses to environmental allergens. Clinical studies suggest that asthma is a heterogeneous disorder with distinct types of inflammatory processes. Accumulating evidence suggests that aberrant interleukin (IL)-17 production is a key determinant of severe forms of asthma. However, the identity of IL-17-producing cells and the factors regulating IL-17 production during the course of allergic inflammation remain elusive. In this review, we summarize the potential IL-17-producing cells and their involvement in the inflammatory responses that mediate distinct features of asthma. The role of proinflammatory cytokines and the complement pathway in regulating the generation of IL-17-producing T cells is also discussed. Understanding the biology of IL-17 in the context of allergic inflammation may be informative in the development of novel approaches to the diagnosis and treatment of asthma.

Mycoplasma pneumoniae Infection Affects the Serum Levels of Vascular Endothelial Growth Factor and Interleukin-5 in Atopic Children

PURPOSE

Previous studies have outlined mechanisms by which Mycoplasma pneumonia (M. pneumonia) infection may promote allergic lung inflammation and airway remodeling, and increasing evidence from human studies suggests that atypical bacterial infections contribute to asthma exacerbation, chronic asthma, and disease severity with changes in cytokine expression. The present study evaluated changes in serum levels of vascular endothelial growth factor (VEGF) and interleukin (IL)-5 in atopic children with Mycoplasma pneumoniae pneumonia.

METHODS

We recruited a total of 72 children with pneumonia. The patients were divided into 4 groups: atopic children with M. pneumonia pneumonia (group I, n=24), non-atopic children with M. pneumonia pneumonia (group II, n=23), atopic children with viral pneumonia (group III, n=13), and non-atopic children with viral pneumonia (group IV, n=12). Serum levels of IL-5, IL-13, VEGF, and tumor necrosis factor-α were measured at admission and at recovery using enzyme-linked immunosorbent assays.

RESULTS

Serum levels of VEGF and IL-5 were elevated in group I compared with the other groups at both admission phase and clinical recovery phase. In group I, serum levels of VEGF and IL-5 were higher at recovery phase than at admission phase (VEGF: 1,102.2±569.4 vs. 874.9±589.9 pg/mL, respectively; IL-5: 150.5±63.9 vs. 120.2±46.7 pg/mL, respectively).

CONCLUSIONS

The serum levels of VEGF and IL-5 were more increased in atopic children with M. pneumonia pneumonia than in the other groups. In this group, the serum levels of VEGF and IL-5 were more increased at recovery phase than at admission phase. The results of this study suggest that increases in VEGF and IL-5 may contribute to the development of hypersensitivity during M. pneumonia infection. These cytokines may act through their respective pro-inflammatory pathways to aggravate the allergic status and induce airway hypersensitivity during M. pneumonia pneumonia in atopic children.

Perspectives of purinergic signaling in stem cell differentiation and tissue regeneration

Replacement of lost or dysfunctional tissues by stem cells has recently raised many investigations on therapeutic applications. Purinergic signaling has been shown to regulate proliferation, differentiation, cell death, and successful engraftment of stem cells originated from diverse origins. Adenosine triphosphate release occurs in a controlled way by exocytosis, transporters, and lysosomes or in large amounts from damaged cells, which is then subsequently degraded into adenosine. Paracrine and autocrine mechanisms induced by immune responses present critical factors for the success of stem cell therapy. While P1 receptors generally exert beneficial effects including anti-inflammatory activity, P2 receptor-mediated actions depend on the subtype of stimulated receptors and localization of tissue repair. Pro-inflammatory actions and excitatory tissue damages mainly result from P2X7 receptor activation, while other purinergic receptor subtypes participate in proliferation and differentiation, thereby providing adequate niches for stem cell engraftment and novel mechanisms for cell therapy and endogenous tissue repair. Therapeutic applications based on regulation of purinergic signaling are foreseen for kidney and heart muscle regeneration, Clara-like cell replacement for pulmonary and bronchial epithelial cells as well as for induction of neurogenesis in case of neurodegenerative diseases.

Histamine-releasing factor has a proinflammatory role in mouse models of asthma and allergy

IgE-mediated activation of mast cells and basophils underlies allergic diseases such as asthma. Histamine-releasing factor (HRF; also known as translationally controlled tumor protein [TCTP] and fortilin) has been implicated in late-phase allergic reactions (LPRs) and chronic allergic inflammation, but its functions during asthma are not well understood. Here, we identified a subset of IgE and IgG antibodies as HRF-interacting molecules in vitro. HRF was able to dimerize and bind to Igs via interactions of its N-terminal and internal regions with the Fab region of Igs. Therefore, HRF together with HRF-reactive IgE was able to activate mast cells in vitro. In mouse models of asthma and allergy, Ig-interacting HRF peptides that were shown to block HRF/Ig interactions in vitro inhibited IgE/HRF-induced mast cell activation and in vivo cutaneous anaphylaxis and airway inflammation. Intranasally administered HRF recruited inflammatory immune cells to the lung in naive mice in a mast cell- and Fc receptor-dependent manner. These results indicate that HRF has a proinflammatory role in asthma and skin immediate hypersensitivity, leading us to suggest HRF as a potential therapeutic target.

Tiarellic acid attenuates airway hyperresponsiveness and inflammation in a murine model of allergic asthma

Asthma is a persistent inflammatory disease characterized by airway obstruction and hyperresponsiveness in association with airway inflammation. In the current research, we studied the anti-inflammatory and anti-asthmatic effects of tiarellic acid (TA) isolated from Tiarella polyphylla, based on asthmatic parameters, such as immunoglobulin E (IgE) level, cytokine release, eosinophilia, airway hyperresponsiveness (AHR), reactive oxygen species (ROS) and mucus hypersecretion, in an ovalbumin (OVA)-sensitized/challenged mouse model. TA significantly inhibited increases in IgE, levels of ROS and T helper cytokines, such as interleukin (IL)-4, IL-5, TNF-α, and IL-13, in bronchoalveolar lavage fluid (BALF), and effectively suppressed airway hyperresponsiveness, eosinophilia, and mucus hypersecretion in the asthmatic mouse model. In addition, we found that administration of TA attenuated ovalbumin-induced increases in NF-κB activity in lungs. The efficacy of TA was comparable to that of montelukast, a currently available anti-asthmatic drug. Our results support the utility of TA as a herbal medicine for asthma treatment and may have application in the development of anti-inflammatory and anti-asthmatic drugs.

IL-22 attenuates IL-25 production by lung epithelial cells and inhibits antigen-induced eosinophilic airway inflammation

BACKGROUND

IL-22 functions as both a proinflammatory cytokine and an anti-inflammatory cytokine in various inflammations, depending on the cellular and cytokine milieu. However, the roles of IL-22 in the regulation of allergic airway inflammation are still largely unknown.

OBJECTIVE

We sought to determine whether IL-22 is involved in the regulation of allergic airway inflammation.

METHODS

We examined IL-22 production and its cellular source at the site of antigen-induced airway inflammation in mice. We also examined the effect of IL-22 neutralization, as well as IL-22 administration, on antigen-induced airway inflammation. We finally examined the effect of IL-22 on IL-25 production from a lung epithelial cell line (MLE-15 cells).

RESULTS

Antigen inhalation induced IL-22 production in the airways of sensitized mice. CD4(+) T cells, but not other lymphocytes or innate cells, infiltrating in the airways produced IL-22, and one third of IL-22-producing CD4(+) T cells also produced IL-17A. The neutralization of IL-22 by anti-IL-22 antibody enhanced antigen-induced IL-13 production, eosinophil recruitment, and goblet cell hyperplasia in the airways. On the other hand, intranasal administration of recombinant IL-22 attenuated antigen-induced eosinophil recruitment into the airways. Moreover, anti-IL-22 antibody enhanced antigen-induced IL-25 production in the airways, and anti-IL-25 antibody reversed the enhancing effect of anti-IL-22 antibody on antigen-induced eosinophil recruitment into the airways. Finally, IL-22 inhibited IL-13-mediated enhancement of IL-25 expression in IL-1β- or LPS-stimulated MLE-15 cells.

CONCLUSION

IL-22 attenuates antigen-induced airway inflammation, possibly by inhibiting IL-25 production by lung epithelial cells.

Effects of curcumin on lung histopathology and fungal burden in a mouse model of chronic asthma and oropharyngeal candidiasis

BACKGROUND AND AIMS

Oropharyngeal candidiasis (OPC) is one of the most common local side effects of current therapy in chronic asthma. New therapeutic options with fewer side effects and reverse chronic changes are needed. Curcumin, as a promising antiinflammatory and antifungal agent, could be a candidate of alternative therapy in asthma. This study aimed to determine the efficacy of orally administrated curcumin on lung histopathology, serum nitric oxide levels and fungal burden in a murine model of asthma and OPC.

METHODS

Thirty five BALB/c mice were divided into five groups: I, II, III, IV (placebo) and V (control). All groups except the control were sensitized and challenged with ovalbumin. OPC model was established after the model of chronic asthma. Lung histology, serum nitric oxide levels and fungal burden were evaluated after 5 days of treatment with curcumin, dexamethasone, curcumin-dexamethasone combination and placebo. Evaluation of lung histology included subepithelial smooth muscle and epithelial thickness and number of goblet and mast cells by using light microscopy.

RESULTS

All histological parameters improved in curcumin group similar to dexamethasone group. Curcumin and dexamethasone-curcumin combination were also as effective as dexamethasone on decreasing nitric oxide levels. Oral fungal burden was significantly lower in curcumin-treated group than dexamethasone.

CONCLUSIONS

In our study we demonstrated that curcumin administration alleviates the pathological changes in asthma and decreases the fungal burden. Curcumin may have a potential effect on treating chronic asthma and decreasing the frequency of the OPC.

Extracellular cyclophilin levels associate with parameters of asthma in phenotypic clusters

OBJECTIVE

Leukocyte persistence during chronic (quiescent) phases of asthma is a major hallmark of the disease. The mechanisms regulating these persistent leukocyte populations are not clearly understood. An alternative family of chemoattracting proteins, cyclophilins (Cyps), has recently been shown to contribute to leukocyte recruitment in animal models of allergic asthma. The goals of this study were to determine whether Cyps are present in asthma patients during the chronic phase of the disease and to investigate whether levels of Cyps associate with clinical parameters of disease severity.

METHODS

Nasal wash samples from an urban cohort of 137 patients of age 6-20 years with physician-diagnosed asthma were examined for the presence of cyclophilin A (CypA), cyclophilin B (CypB), as well as several other classical chemokines. Linear, logistic, or ordinal regressions were performed to identify associations between Cyps, chemokines, and clinical parameters of asthma. The asthma cohort was further divided into previously established phenotypic clusters (cluster 1: n = 55; cluster 2: n = 31; and cluster 3: n = 51) and examined for associations.

RESULTS

Levels of CypB in the asthma group were highly elevated compared to nonasthmatic controls, while a slight increase in Monocyte Chemotactic Protein-1 (MCP-1) was also observed. CypA and MCP-1 were associated with levels of eosinophil cationic protein (ECP; a marker of eosinophil activation). Cluster-specific associations were found for CypA and CypB and clinical asthma parameters [e.g. forced expiratory volume in 1 second (FEV(1)) and ECP].

CONCLUSIONS

Cyps are present in nasal wash samples of asthma patients and may be a novel biomarker for clinical parameters of asthma severity.

A prophylactic effect of an oligodeoxynucleotide containing a cytidine-guanosine motif against Japanese cedar pollen-induced T-helper type 2 allergic response

BACKGROUND

Over 10% of entire population in Japan suffer from allergic diseases induced by Japanese cedar pollen (JCP) every spring. In terms of preventive medicine, it has become a matter of urgency to establish successful prophylactic and therapeutic strategies for controlling the disorders. The effect of an oligodeoxynucleotide containing a cytidine-guanosine motif (CpG ODN) on the regulation of immune responses induced by JCP was investigated in this study.

METHODS

BALB/c mice were inoculated with CpG ODN intraperitoneally before intranasal sensitization to JCP. Cellular infiltration in the lung of BALB/c mice after treatment with CpG ODN or JCP was performed by hematoxylin and eosin (H&E) staining. Antibody titers and cytokines levels were determined by ELISA.

RESULTS

Intranasal inoculation of BALB/c mice with JCP induced a T-helper type 2 (Th2-type) dominant immune response, as characterized by the production of interleukin (IL)-4 and IL-5 in the lung and of JCP-specific IgE antibody in serum. Prior intraperitoneal administration of CpG ODN to mice suppressed the subsequent JCP-induced antibody production and infiltration of inflammatory cells in the lung. The inhibitory mechanism of CpG ODN seemed to be attributable to a CpG ODN-induced Th1-type dominant environment, which down-regulated Th2-type response subsequently induced by JCP allergen sensitization. Furthermore, administration with CpG ODN decreased the production of JCP-induced IL-17, which has been found to play a pivotal role in several inflammatory diseases including allergic asthma. The decreased production of IL-17, together with reduced secretion of IL-4 and IL-5, may contribute to diminish the inflammation in the lung of JCP-sensitized mice.

CONCLUSION

This work provides evidence that the CpG ODN has a prophylactic effect on the JCP-induced Th2-type allergic responses by establishing or restoring a Th1-type shift of immune environments.

Identification of an IFN-γ/mast cell axis in a mouse model of chronic asthma

Asthma is considered a Th2 cell–associated disorder. Despite this, both the Th1 cell–associated cytokine IFN-γ and airway neutrophilia have been implicated in severe asthma. To investigate the relative contributions of different immune system components to the pathogenesis of asthma, we previously developed a model that exhibits several features of severe asthma in humans, including airway neutrophilia and increased lung IFN-γ. In the present studies, we tested the hypothesis that IFN-γ regulates mast cell function in our model of chronic asthma. Engraftment of mast cell–deficient KitW(-sh/W-sh) mice, which develop markedly attenuated features of disease, with wild-type mast cells restored disease pathology in this model of chronic asthma. However, disease pathology was not fully restored by engraftment with either IFN-γ receptor 1–null (Ifngr1–/–) or Fcε receptor 1γ–null (Fcer1g–/–) mast cells. Additional analysis, including gene array studies, showed that mast cell expression of IFN-γR contributed to the development of many FcεRIγ-dependent and some FcεRIγ-independent features of disease in our model, including airway hyperresponsiveness, neutrophilic and eosinophilic inflammation, airway remodeling, and lung expression of several cytokines, chemokines, and markers of an alternatively activated macrophage response. These findings identify a previously unsuspected IFN-γ/mast cell axis in the pathology of chronic allergic inflammation of the airways in mice.

Macrophage colony stimulating factor and monocyte chemoattractant protein 2 are elevated in intrinsic asthmatics

BACKGROUND

Intrinsic asthma, etiology unknown, occurs later in life, mostly in females. It is associated with nasal polyps and massive eosinopillic infiltration of the respiratory mucous membrane, aspirin intolerance and steroid dependence. The aim of the study was to determine the cytokine and chemokine profile in sera of intrinsic asthmatics and control subjects.

METHODS

Blood was taken from 10 intrinsic asthmatic female and 12 control female subjects. Expression profile of 42 different cytokines and chemokines were measured using a microarray composed of antibodies against the cytokines and chemokines. Complete blood count and C-reactive protein were measured, to assess the state of inflammation in both groups.

RESULTS

We have identified Macrophage Colony Stimulating Factor, a proinflammatory cytokine and Monocyte Chemoattractant Protein 2, a CC chemokine as having significantly higher expression levels in intrinsic asthmatic subjects compared to controls (341.71±31.28 SEM Signal intensity) versus (247.97±28.09 SEM Signal intensity), p=0.036 and (397.07±38.19 SEM Signal intensity) versus (311.33±28.76 SEM Signal intensity), p=0.036, respectively. There were no significant differences in the other cytokines and chemokines measured nor were there any differences in the inflammatory measurements between the two groups except for eosinophil counts, the hall mark of intrinsic asthma.

CONCLUSION

Macrophage Colony Stimulating Factor and Monocyte Chemoattractant Protein are elevated in sera of intrinsic asthmatics compared to normal controls. These cytokines may have a critical role in the inflammatory pathology of intrinsic asthma.

Invariant NKT cell defects in vitamin D receptor knockout mice prevents experimental lung inflammation

Vitamin D receptor (VDR) deficiency (knockout [KO]) results in a failure of mice to generate an airway hyperreactivity (AHR) response on both the BALB/c and C57BL/6 background. The cause of the failed AHR response is the defective population of invariant NKT (iNKT) cells in the VDR KO mice because wild-type (WT) iNKT cells rescued the AHR response. VDR KO mice had significantly fewer iNKT cells and normal numbers of T cells in the spleen compared with WT mice. In BALB/c VDR KO mice, the reduced frequencies of iNKT cells were not apparent in the liver or thymus. VDR KO and WT Th2 cells produced similar levels of IFN-γ and IL-5. On the BALB/c background, Th2 cells from VDR KO mice produced less IL-13, whereas on the C57BL/6 background, Th2 cells from VDR KO mice produced less IL-4. Conversely, VDR KO iNKT cells were defective for the production of multiple cytokines (BALB/c: IL-4, IL-5, and IL-13; C57BL/6: IL-4 and IL-17). Despite relatively normal Th2 responses, BALB/c and C57BL/6 VDR KO mice failed to develop AHR responses. The defect in iNKT cells as a result of the VDR KO was more important than the highly susceptible Th2 background of the BALB/c mice. Defective iNKT cell responses in the absence of the VDR result in the failure to generate AHR responses in the lung. The implication of these mechanistic findings for human asthma requires further investigation.

CD44 is critical for airway accumulation of antigen-specific Th2, but not Th1, cells induced by antigen challenge in mice

CD44 is a cell adhesion molecule involved in lymphocyte infiltration of inflamed tissues. We previously demonstrated that CD44 plays an important role in the development of airway inflammation in a murine model of allergic asthma. In this study, we investigated the role of CD44 expressed on CD4(+) T cells in the accumulation of T-helper type 2 (Th2) cells in the airway using CD44-deficient mice and anti-CD44 monoclonal antibodies. Antigen-induced Th2-mediated airway inflammation and airway hyperresponsiveness (AHR) in sensitized mice were reduced by CD44-deficiency. These asthmatic responses induced by the transfer of antigen-sensitized splenic CD4(+) T cells from CD44-deficient mice were weaker than those from WT mice. Lack of CD44 failed to induce AHR by antigen challenge. Expression level and hyaluronic acid receptor activity of CD44, as well as Neu1 sialidase expression on antigen-specific Th2 cells, were higher than those on antigen-specific Th1 cells. Anti-CD44 antibody preferentially suppressed the accumulation of those Th2 cells in the airway induced by antigen challenge. Our findings indicate that CD44 expressed on CD4(+) T cells plays a critical role in the accumulation of antigen-specific Th2 cells, but not Th1 cells, in the airway and in the development of AHR induced by antigen challenge.

Antiasthmatic effects of Gleditsia sinensis in an ovalbumin-induced murine model of asthma

This study evaluated the antiasthmatic effects of Gleditsia sinensis ethanolic extract (GSEE) and its underlying mechanisms, using an in vivo murine model of asthma. Female BALB/c mice were sensitized, challenged with ovalbumin, and then examined for asthmatic reactions. The results showed that GSEE exerted profound inhibitory effects on the accumulation of eosinophils in the airways and reduced the levels of interleukin (IL)-4 and IL-5 in bronchoalveolar lavage fluid (BALF) and immunoglobulin E (IgE) in BALF and plasma. Gleditsia sinensis ethanolic extract also suppressed the production of reactive oxygen species in BALF and inflammatory infiltration, in a dose-dependent manner, and it inhibited goblet-cell hyperplasia in lung tissue. Thus, GSEE shows antiasthmatic effects in a murine model of allergic asthma, which appeared to be mediated partially by the reduction of oxidative stress and airway inflammation. These results indicate that GSEE could be an effective novel therapeutic agent for the treatment of allergic asthma.

Low-dose lipopolysaccharide affects lung allergic responses by regulating Jagged1 expression on antigen-pulsed dendritic cells

BACKGROUND

Notch signaling pathways govern immune function and the regulation of Th1 and Th2 differentiation. We previously demonstrated essential interactions between Notch on CD4+ T cells and Jagged1 on antigen-presenting cells in Th2 differentiation for the full development of allergen-induced airway hyperresponsiveness (AHR) and allergic airway inflammation.

METHODS

Bone marrow-derived dendritic cells (BMDCs) were differentiated and incubated with different preparations of ovalbumin (OVA), including lipopolysaccharide (LPS)-depleted and LPS-spiked preparations. In some experiments recipient mice also received soluble Jagged1-Fc in addition to allergen-pulsed BMDCs. Ten days following transfer of BMDCs, mice were exposed to three airway challenges with OVA, and airway responsiveness to inhaled methacholine, airway inflammation and cytokine production were monitored 48 h later. Notch ligand expression was assessed by real-time PCR.

RESULTS

Induction of Jagged1 expression on antigen-pulsed BMDCs was dependent on low-dose endotoxin. In vivo, transfer of endotoxin-free, antigen-pulsed BMDCs failed to induce AHR or airway eosinophilia on allergen challenge. However, administration of exogenous Jagged1-Fc together with endotoxin-free, allergen-pulsed BMDCs fully restored the responses to allergen challenge.

CONCLUSIONS

These data demonstrate that LPS regulates the expression of Jagged1 on BMDCs, which is essential for the full development of lung allergic responses.

A zinc chelator TPEN attenuates airway hyperresponsiveness and airway inflammation in mice in vivo

BACKGROUND

Zinc is an essential element required for the cell metabolism, including gene transcription, signal transduction, immunity, and apoptosis. The pathophysiological role of zinc in asthma, however, is not entirely clear. Mast cells have been implicated in atopic asthma, and zinc deprivation has been reported to reduce mast cell activation. Here, we investigate the effects of a zinc chelator, N,N,N',N'-tetrakis (2-pyridyl-methyl) ethylenediamine (TPEN), on asthmatic responses in mouse models of ovalbumin (OVA)-induced airway hyperresponsiveness and allergic airway inflammation.

METHODS

Mice were sensitized with OVA with or without the adjuvant aluminum hydroxide (alum) and subjected to OVA exposure with or without treatment of TPEN. Cell profiles and cytokine levels in bronchoalveolar lavage (BAL) fluids, airway responsiveness to inhaled acetylcholine, and goblet cell hyperplasia after allergen exposure were assessed.

RESULTS

In mice sensitized to OVA without alum, TPEN significantly suppressed airway hyperresponsiveness and eosinophilia in BAL fluids. TPEN also attenuated the upregulation of TNFα, IL-13 and IL-4 in BAL fluids and goblet cell hyperplasia after OVA exposure. By contrast, in mice sensitized to OVA with alum, TPEN suppressed eosinophilia in BAL fluids but not airway hyperresponsiveness and goblet cell hyperplasia.

CONCLUSIONS

In pulmonary allergic inflammation induced in mice immunized with antigen without alum, zinc chelator inhibits airway inflammation and hyperresponsiveness. These findings suggest that zinc may be a therapeutic target of allergic asthma.

Effect of heat-inactivated kefir-isolated Lactobacillus kefiranofaciens M1 on preventing an allergic airway response in mice

In this study, we assessed the anti-asthmatic effects of heat-inactivated Lactobacillus kefiranofaciens M1 (HI-M1) and its fermented milk using different feeding procedures and at various dosage levels. The possible mechanisms whereby HI-M1 has anti-allergic asthmatic effects were also evaluated. Ovalbumin (OVA)-allergic asthma mice that have been orally administrated the HI-M1 samples showed strong inhibition of production of T helper cell (Th) 2 cytokines, pro-inflammatory cytokines, and Th17 cytokines in splenocytes and bronchoalveolar fluid compared to control mice. An increase in regulatory T cell population in splenocytes in the allergic asthma mice after oral administration of H1-M1 was also observed. In addition, all of the features of the asthmatic phenotype, including specific IgE production, airway inflammation, and development of airway hyperresponsiveness, were depressed in a dose-dependent manner by treatment. These findings support the possibility that oral feeding of H1-M1 may be an effective way of alleviating asthmatic symptoms in humans.

Dual TCR expression biases lung inflammation in DO11.10 transgenic mice and promotes neutrophilia via microbiota-induced Th17 differentiation

A commonly used mouse model of asthma is based on i.p. sensitization to OVA together with aluminum hydroxide (alum). In wild-type BALB/c mice, subsequent aerosol challenge using this protein generates an eosinophilic inflammation associated with Th2 cytokine expression. By constrast, in DO11.10 mice, which are transgenic for an OVA-specific TCR, the same treatment fails to induce eosinophilia, but instead promotes lung neutrophilia. In this study, we show that this neutrophilic infiltration results from increased IL-17A and IL-17F production, whereas the eosinophilic response could be restored upon blockade of IFN-γ, independently of the Th17 response. In addition, we identified a CD4(+) cell population specifically present in DO11.10 mice that mediates the same inflammatory response upon transfer into RAG2(-/-) mice. This population contained a significant proportion of cells expressing an additional endogenous TCR α-chain and was not present in RAG2(-/-) DO11.10 mice, suggesting dual antigenic specificities. This particular cell population expressed markers of memory cells, secreted high levels of IL-17A, and other cytokines after short-term restimulation in vitro, and triggered a neutrophilic response in vivo upon OVA aerosol challenge. The relative numbers of these dual TCR lymphocytes increased with the age of the animals, and IL-17 production was abolished if mice were treated with large-spectrum antibiotics, suggesting that their differentiation depends on foreign Ags provided by gut microflora. Taken together, our data indicate that dual TCR expression biases the OVA-specific response in DO11.10 mice by inhibiting eosinophilic responses via IFN-γ and promoting a neutrophilic inflammation via microbiota-induced Th17 differentiation.

IgG immune complex induces the recruitment of inflammatory cells into the airway and TNF-mediated late airway hyperresponsiveness via NF-κB activation in mice

BACKGROUND

Many of the inflammatory proteins that are expressed in asthmatic airways are regulated, at least partially, by nuclear factor (NF)-κB. Blockade of NF-κB activity has resulted in attenuation of the cardinal features of asthma. Thus, delineating the mechanisms involved in NF-κB activation in asthma might provide an interesting approach to improving the management of asthma. However, despite its importance, the mechanism for NF-κB activation in asthma has not yet been determined.

OBJECTIVE

To examine the role of IgE and IgG antibodies (Abs) in the activation of NF-κB in mouse lungs.

METHODS

To examine the effect of IgE, mice underwent intratracheal (i.t.) instillation of an IgE immune complex (IgE-IC) (anti-2,4-dinitrophenyl hapten (DNP) IgE + DNP-BSA or DNP-OVA) and anaphylactogenic anti-IgE (LO-ME-2). For IgG, mice underwent i.t. instillation with a complex of anti-chicken gamma globulin (CGG) IgG1 mAb + CGG. NF-κB activation was determined by gel shift assay. Small interfering RNA was used for blockade of p50 expression. The effect of tumor necrosis factor (TNF) blockade was determined using anti-TNF Ab. A previously established murine model of asthma was used to assess airway hyperresponsiveness (AHR).

RESULTS

A single i.t. instillation of either IgE-IC or LO-ME-2 failed to induce activation of NF-κB in the lungs. In contrast, single i.t. instillation of IgG-IC was capable of inducing NF-κB activation, as well as NF-κB-dependent proinflammatory molecules, such as TNF and CXC chemokines. Pretreatment of p50 small interfering RNA decreased bronchoalveolar lavage fluid levels of TNF and macrophage inflammatory protein-2 induced by IgG-IC instillation. Single i.t. instillation of IgG-IC caused the recruitment of neutrophils and macrophages into the airway and TNF-mediated late AHR, but failed to induce Th2 cell-mediated asthmatic phenotypes.

CONCLUSION

IgG, but not IgE, is the major Ab that induces not only NF-κB activation and NF-κB-dependent proinflammatory molecules in the lungs but also subsequent recruitment of inflammatory cells into the airway and TNF-mediated late AHR.

Evolution of IL4 and pathogen antagonism

Interleukin-4 (IL4) is a pleiotropic cytokine involved in host protection from gastrointestinal nematodes. Here, we review the structure, function, and evolutionary history of IL4. Cumulative evidence indicates that over 100 million years of eutherian mammalian evolution, IL4 has experienced multiple episodes of positive selection. We argue that IL4 may have evolved in conflict with pathogen-derived antagonists, and therefore diversified to escape antagonism while being constrained to maintain binding to its cellular receptors. Selective pressure driving IL4 diversification may have arisen from ancient episodes of conflict with parasitic worm-derived IL4 antagonists. Descendants of such antagonists may still equip the armamentarium of contemporary gastrointestinal nematodes.

Cannabinoids as novel anti-inflammatory drugs

Cannabinoids are a group of compounds that mediate their effects through cannabinoid receptors. The discovery of Δ9-tetrahydrocannabinol (THC) as the major psychoactive principle in marijuana, as well as the identification of cannabinoid receptors and their endogenous ligands, has led to a significant growth in research aimed at understanding the physiological functions of cannabinoids. Cannabinoid receptors include CB1, which is predominantly expressed in the brain, and CB2, which is primarily found on the cells of the immune system. The fact that both CB1 and CB2 receptors have been found on immune cells suggests that cannabinoids play an important role in the regulation of the immune system. Recent studies demonstrated that administration of THC into mice triggered marked apoptosis in T cells and dendritic cells, resulting in immunosuppression. In addition, several studies showed that cannabinoids downregulate cytokine and chemokine production and, in some models, upregulate T-regulatory cells (Tregs) as a mechanism to suppress inflammatory responses. The endocannabinoid system is also involved in immunoregulation. For example, administration of endocannabinoids or use of inhibitors of enzymes that break down the endocannabinoids, led to immunosuppression and recovery from immune-mediated injury to organs such as the liver. Manipulation of endocannabinoids and/or use of exogenous cannabinoids in vivo can constitute a potent treatment modality against inflammatory disorders. This review will focus on the potential use of cannabinoids as a new class of anti-inflammatory agents against a number of inflammatory and autoimmune diseases that are primarily triggered by activated T cells or other cellular immune components.