Human cystatin SN is an endogenous protease inhibitor that prevents allergic rhinitis.

BACKGROUND: Protease allergens disrupt epithelial barriers to exert their allergenicity. Cystatin SN (encoded by CST1) is an endogenous cysteine protease inhibitor upregulated in nasal epithelia in patients with allergic rhinitis (AR). OBJECTIVE: We sought to investigate the protective effect of human cystatin SN on AR symptoms using pollen-induced AR mouse models. METHODS: We performed an in vitro protease activity assay to evaluate the effect of recombinant human cystatin SN (rhCystatin SN) on Japanese cedar (JC) or ragweed proteases. A human nasal epithelial cell line, RPMI 2650, was used to examine tight junction (TJ) disruption in vitro. Mice were sensitized and nasally challenged with JC or ragweed pollens with or without rhCystatin SN to examine the effect of rhCystatin SN on AR symptoms and the epithelial barrier in vivo. Because mice lack CST1, we generated transgenic (Tg) mice expressing human CST1 under control of its genomic control region (hCST1-Tg mice) to examine the role of cystatin SN in physiologically expressed conditions. RESULTS: rhCystatin SN inhibited JC but not ragweed protease activities and prevented JC-induced but not ragweed-induced TJ disruption in vitro. Exogenous administration of rhCystatin SN ameliorated JC-induced but not ragweed-induced sneezing and nasal TJ disruption in vivo. Furthermore, hCST1-Tg mice showed decreased JC-induced but not ragweed-induced sneezing symptoms and nasal TJ disruption compared with wild-type mice. CONCLUSION: Human cystatin SN suppresses AR symptoms through inhibiting allergen protease activities and protecting the nasal TJ barrier in an allergen-specific manner. We propose that upregulation of nasal endogenous protease inhibitors, including cystatin SN, is a novel therapeutic strategy for protease allergen-induced AR.

From allergen to oral vaccine carrier: A new face of ragweed pollen.

Oral delivery of vaccines is highly desirable, yet it has met with limited success. Previously we developed allergen-free pollen grains as a novel approach for oral vaccination. We showed that spores of Lycopodium clavatum can be used for oral vaccination. However, it is unknown if pollens of other species can be similarly used as an oral vaccine carrier. Therefore, in this study, we evaluated common ragweed (RW) pollen (Ambrosia elatior) for its oral vaccination potential. Allergen-free RW pollens were prepared from natural pollens through chemical treatment. Eight weekly oral doses of ovalbumin (OVA) formulated with treated RW generated strong systemic (anti-OVA IgG, IgG1, IgG2a, and IgA) and mucosal (anti-OVA IgA) immune responses that sustained for at least three months after vaccination. Mucosal IgA against OVA was found in the lung lavage, feces, saliva, and vaginal secretion. Moreover, three and half months after the last immunization OVA-specific plasma cells were found in the bone marrow that actively secreted IgG and IgG1 antibodies. No IgE against RW-specific proteins was detected in the serum. Overall, RW pollen demonstrated potential for oral vaccine delivery.

Distinct epitope structures of defensin-like proteins linked to proline-rich regions give rise to differences in their allergenic activity.

BACKGROUND: Art v 1, Amb a 4, and Par h 1 are allergenic defensin-polyproline-linked proteins present in mugwort, ragweed, and feverfew pollen, respectively. We aimed to investigate the physicochemical and immunological features underlying the different allergenic capacities of those allergens. METHODS: Recombinant defensin-polyproline-linked proteins were expressed in E. coli and physicochemically characterized in detail regarding identity, secondary structure, and aggregation status. Allergenic activity was assessed by mediator releases assay, serum IgE reactivity, and IgE inhibition ELISA using sera of patients from Austria, Canada, and Korea. Endolysosomal protein degradation and T-cell cross-reactivity were studied in vitro. RESULTS: Despite variations in the proline-rich region, similar secondary structure elements were observed in the defensin-like domains. Seventy-four percent and 52% of the Austrian and Canadian patients reacted to all three allergens, while Korean patients were almost exclusively sensitized to Art v 1. This was reflected by IgE inhibition assays demonstrating high cross-reactivity for Austrian, medium for Canadian, and low for Korean sera. In a subgroup of patients, IgE reactivity toward structurally altered Amb a 4 and Par h 1 was not changed suggesting involvement of linear epitopes. Immunologically relevant endolysosomal stability of the defensin-like domain was limited to Art v 1 and no T-cell cross-reactivity with Art v 125-36 was observed. CONCLUSIONS: Despite structural similarity, different IgE-binding profiles and proteolytic processing impacted the allergenic capacity of defensin-polyproline-linked molecules. Based on the fact that Amb a 4 demonstrated distinct IgE-binding epitopes, we suggest inclusion in molecule-based allergy diagnosis.

Total and allergen-specific immunoglobulin E in the serum and nasal mucosa of a nonallergic population.

BACKGROUND: There has been a growing interest in measuring allergen-specific immunoglobulin E (sIgE) directly from the nasal mucosal epithelium of individuals with sinonasal disease. However, there is currently no normative data with which to estimate sensitivity, specificity, and the appropriate positive cutoff level for new testing methods. METHODS: Twenty individuals with no history of sinonasal disease or food allergies underwent serum IgE testing and nasal mucosal brush biopsy (MBB) testing for total and sIgE to 7 common airborne allergens and 1 food allergen. The correlation between sIgE in serum and nasal samples was determined at both the 0.10-kU/L and 0.35-kU/L positive cutoff levels. RESULTS: sIgE at the 0.35-kU/L cutoff level was detected for at least 1 allergen in 7 of 20 (35%) participants in both the serum and nose. At the 0.10-kU/L cutoff level, 8 of 20 (40%) and 19 of 20 (95%) participants had sIgE to at least 1 allergen in the serum and nose, respectively. At the 0.35-kU/L cutoff level, total serum IgE levels were significantly higher when at least 1 allergen was detected in the nose (p = 0.01). There was a strong association between sIgE in the serum and nasal mucosa (p < 0.0001) at both cutoff levels. CONCLUSION: The significant association between serum and nasal samples for both total and sIgE suggests that nasal IgE and serum IgE are not independent of one another. Understanding levels of IgE in the nonallergic population will help answer the questions surrounding sensitization as new diagnostic tests for locally-present IgE become available.

Inhibition of MDM2 expression by rosmarinic acid in TSLP-stimulated mast cell.

Rosmarinic acid (RA) has an anti-inflammatory property while thymic stromal lymphopoietin (TSLP) has an important role in mast cell-mediated inflammatory responses. Thus, the aim of this study was to determine the regulatory effect of RA in TSLP-stimulated human mast cell line, HMC-1 cells, and short ragweed pollen-induced allergic conjunctivitis mouse model. As a result, we found that RA significantly decreased the TSLP-induced mast cell proliferation and murine double minute (MDM) 2 expression. RA significantly decreased the levels of interleukin (IL)-13 and phosphorylated the signal transducer and activation of transcription 6 in the TSLP-stimulated HMC-1 cells. RA induced the increment of p53 levels, caspase-3 activation, and poly-ADP-ribose polymerase cleavage and the reduction of the procaspase-3 and Bcl2. RA significantly reduced the production of tumor necrosis factor-α, IL-1ß, and IL-6 on the TSLP-stimulated HMC-1 cells. In addition, RA significantly reduced the levels of IgE, IL-4, and TSLP in the short ragweed pollen-induced allergic conjunctivitis mouse model. In conclusion, the results of the study suggest that RA has a significant anti-inflammatory effect on TSLP-induced inflammatory reactions. These effects of RA are likely to be mediated through inhibiting the MDM2 increased by TSLP.

Cockroach sensitization mitigates allergic rhinoconjunctivitis symptom severity in patients allergic to house dust mites and pollen.

BACKGROUND: Modifiers of symptom severity in patients with allergic rhinoconjunctivitis (AR) are imprecisely characterized. The hygiene hypothesis implicates childhood microbial exposure as a protective factor. Cockroach sensitization (C+) might be a proxy for microbial exposure. OBJECTIVE: We sought to determine whether C+ assayed by means of skin prick tests influenced AR symptom severity in controlled and natural settings. METHODS: Total symptom scores (TSSs) were recorded by 21 participants with house dust mite allergy (M+) in the natural setting and during repeated exposures of 3 hours per day to house dust mite allergen in an allergen challenge chamber (ACC). In M+ participants the peripheral blood and nasal cells were assayed for T-cell activation and transcriptomic profiles (by using RNA sequencing), respectively. Participants allergic to mountain cedar (n = 21), oak (n = 34), and ragweed (n = 23) recorded TSSs during separate out-of-season exposures to these pollens (any pollen sensitization [P+]) in the ACC; a subset recorded TSSs in the pollination seasons. RESULTS: The hierarchy of TSSs (highest to lowest) among M+ participants tracked the following skin prick test sensitization statuses: M+P+C- > M+P+C+ > M+P-C- > M+P-C+. In nasal cells and peripheral blood the immune/inflammatory responses were rapidly resolved in M+P+C+ compared with M+P+C- participants. Among those allergic to pollen, C+ was associated with a lower TSS during pollen challenges and the pollination season. After aggregated analysis of all 4 ACC studies, C+ status was associated with a 2.8-fold greater likelihood of a lower TSS compared with C- status (odds ratio, 2.78; 95% CI, 1.18-6.67; P = .02). CONCLUSIONS: C+ status is associated with mitigation of AR symptom severity in adults with AR.

Identification of the cysteine protease Amb a 11 as a novel major allergen from short ragweed.

BACKGROUND: Allergy to pollen from short ragweed (Ambrosia artemisiifolia) is a serious and expanding health problem in the United States and in Europe. OBJECTIVE: We sought to investigate the presence of undescribed allergens in ragweed pollen. METHODS: Ragweed pollen proteins were submitted to high-resolution gel electrophoresis and tested for IgE reactivity by using sera from 92 American or European donors with ragweed allergy. Pollen transcriptome sequencing, mass spectrometry (MS), and recombinant DNA technologies were applied to characterize new IgE-binding proteins. RESULTS: High-resolution IgE immunoblotting experiments revealed that 50 (54%) of 92 patients with ragweed allergy were sensitized to a 37-kDa allergen distinct from Amb a 1. The full-length cDNA sequence for this molecule was obtained by means of PCR cloning after MS sequencing of the protein combined with ragweed pollen RNA sequencing. The purified allergen, termed Amb a 11, was fully characterized by MS and confirmed to react with IgEs from 66% of patients. This molecule is a 262-amino-acid thiol protease of the papain family expressed as a combination of isoforms and glycoforms after proteolytic removal of N- and C-terminal propeptides from a proform. Three-dimensional modeling revealed a high structural homology with known cysteine proteases, including the mite Der p 1 allergen. The protease activity of Amb a 11, as well as its capacity to activate basophils from patients with ragweed allergy, were confirmed. The production of a nonglycosylated recombinant form of Amb a 11 in Escherichia coli established that glycosylation is not required for IgE binding. CONCLUSION: We identified the cysteine protease Amb a 11 as a new major allergen from ragweed pollen. Given the similar physicochemical properties shared by the 2 major allergens, we hypothesize that part of the allergenic activity previously ascribed to Amb a 1 is rather borne by Amb a 11.

Culture medium from TNF-α-stimulated mesenchymal stem cells attenuates allergic conjunctivitis through multiple antiallergic mechanisms.

BACKGROUND: The immunomodulatory and anti-inflammatory functions of mesenchymal stem cells (MSCs) have been demonstrated in several autoimmune/inflammatory diseases, but their contribution to allergic conjunctivitis and underlying antiallergic mechanisms remain elusive. OBJECTIVE: We sought to explore the clinical application of MSCs to experimental allergic conjunctivitis (EAC) and its underlying antiallergic mechanisms. METHODS: Culture medium from TNF-α-stimulated, bone marrow-derived MSCs (MSC-CMT) was administered topically to mice with EAC, and the related allergic symptoms and biological changes were evaluated. Murine spleen-derived B cells, bone marrow-derived mast cells (MCs), and lung vascular endothelial cells were cultured in vitro to investigate the antiallergic MSC-CMT mechanisms. RESULTS: Topical instillation of MSC-CMT significantly attenuated the clinical symptoms of short ragweed pollen-induced EAC, with a significant decrease in inflammatory cell frequency, nuclear factor κB p65 expression, and TNF-α and IL-4 production. In vitro MSC-CMT significantly inhibited the activation of MCs and B-cell IgE release and reduced histamine-induced vascular hyperpermeability. During EAC, MSC-CMT treatment also decreased IgE production, histamine release, enrichment and activation of MCs, and conjunctival vascular hyperpermeability. The MSC-CMT-mediated inhibition of B cells, MCs, and histamine and its antiallergic effects during EAC were abrogated when MSCs were pretreated with COX2 small interfering RNA. CONCLUSIONS: Our findings provide compelling evidence that MSC-CMT inhibits EAC through COX2-dependent multiple antiallergic mechanisms and support the use of MSC-CMT as a novel strategy for treating allergic conjunctivitis.

Dietary intervention for oral allergy syndrome as a treatment in orofacial granulomatosis: a new approach?

BACKGROUND: Orofacial granulomatosis (OFG) is a chronic granulomatous condition of the mouth, face and lips. Recent work demonstrates a high rate of atopy and silver birch sensitisation from skin prick testing (SPT). Oral allergy syndrome (OAS) is an acute oro-pharyngeal IgE mediated reaction, triggered by foods that cross react with pollens, most commonly silver birch. The aim of this study was to determine if patients with OFG and positive SPT to common OAS associated pollens responded to avoidance of cross reactive foods. METHODS: Patients with OFG and positive SPT to silver birch, grass, mugwort, ragweed and latex were required to avoid cross reacting foods, for 6 weeks and, in those who responded, for a total of 12 weeks. All had standardized oral examinations and were given severity scores (SS) at each appointment. RESULTS: Twenty two of 47 (47%) patients had one or more positive SPT and 13/22 completed 6 weeks on the diet. No difference was seen in SS between weeks 0 (14.62 ± 11.16) and 6 (13.31 ± 10.33; P = 0.656). Six of 14 (43%) had significantly improved SS (week 0; 19.17 ± 12.95, week 6; 10.83 ± 4.99, P = 0.027). Five completed 12 weeks and no further improvement was seen (week 6; 11 ± 5.57, week 12; 10.4 ± 9.94; P = 0.068). Two patients required no further treatments. CONCLUSIONS: On an intention to treat basis, only 2/14 patients improved and required no further intervention. Whilst this diet cannot be recommended routinely, the improvement seen in some patients raises questions about the role of OAS in patients with OFG.

The effects of various doses of bacterial lipopolysaccharide on the expression of CD63 and the release of histamine by basophils of atopic and non-atopic patients.

OBJECTIVE: We tested the effect of various doses of bacterial lipopolysaccharide (LPS, endotoxin) on the expression of CD63 and the in vitro release of histamine by basophils stimulated with ragweed allergen in patients with or without ragweed and mite allergies. METHODS: The peripheral blood of 11 patients with ragweed allergy, 10 patients with mite allergy and 14 control patients was incubated with ragweed allergen extract following pretreatment with varying doses of LPS. The expression of CD63 in basophils was measured by flow cytometry, and the release of histamine was determined by ELISA. RESULTS: In the samples of patients with ragweed allergy that were exposed to specific allergen, only high doses of LPS significantly elevated the expression of CD63 (200 ng/ml; 1,000 EU/ml) and the release of histamine (2,000 ng/ml; 10,000 EU/ml). There was no effect of LPS in any other cases. CONCLUSIONS: Bacterial LPS (endotoxin) concentrations higher than 200 ng/ml (1,000 EU/ml), which rarely occurs in nature, could only activate the basophils from atopic patients whilst in the presence of the specific allergen. Thus, the restoration of the urban, "microbe-poor" milieu with endotoxin (as LPS) can be a promising and harmless approach for allergy prevention.

Ragweed subpollen particles of respirable size activate human dendritic cells.

Ragweed (Ambrosia artemisiifolia) pollen grains, which are generally considered too large to reach the lower respiratory tract, release subpollen particles (SPPs) of respirable size upon hydration. These SPPs contain allergenic proteins and functional NAD(P)H oxidases. In this study, we examined whether exposure to SPPs initiates the activation of human monocyte-derived dendritic cells (moDCs). We found that treatment with freshly isolated ragweed SPPs increased the intracellular levels of reactive oxygen species (ROS) in moDCs. Phagocytosis of SPPs by moDCs, as demonstrated by confocal laser-scanning microscopy, led to an up-regulation of the cell surface expression of CD40, CD80, CD86, and HLA-DQ and an increase in the production of IL-6, TNF-α, IL-8, and IL-10. Furthermore, SPP-treated moDCs had an increased capacity to stimulate the proliferation of naïve T cells. Co-culture of SPP-treated moDCs with allogeneic CD3(+) pan-T cells resulted in increased secretion of IFN-γ and IL-17 by T cells of both allergic and non-allergic subjects, but induced the production of IL-4 exclusively from the T cells of allergic individuals. Addition of exogenous NADPH further increased, while heat-inactivation or pre-treatment with diphenyleneiodonium (DPI), an inhibitor of NADPH oxidases, strongly diminished, the ability of SPPs to induce phenotypic and functional changes in moDCs, indicating that these processes were mediated, at least partly, by the intrinsic NAD(P)H oxidase activity of SPPs. Collectively, our data suggest that inhaled ragweed SPPs are fully capable of activating dendritic cells (DCs) in the airways and SPPs' NAD(P)H oxidase activity is involved in initiation of adaptive immune responses against innocuous pollen proteins.

B and T lymphocyte attenuator regulates the development of antigen-induced experimental conjunctivitis.

PURPOSE: To investigate the roles that B and T lymphocyte attenuator (BTLA) and herpesvirus entry mediator (HVEM) play in the development of antigen-induced experimental conjunctivitis (EC). METHODS: BALB/c mice were immunized with ragweed (RW) in alum. Ten days later, the mice were challenged with RW in eye drops. After 24 hours, the conjunctivas, blood and spleens were collected for histological analysis, measurement of serum immunoglobulin (Ig) levels, and both flow cytometric analysis and cytokine assays, respectively. The mice were injected intraperitoneally with anti-BTLA antibody, anti-HVEM antibody or control antibody during either induction phase or effector phase. RESULTS: Induction-phase treatment with anti-BTLA antibody but not anti-HVEM antibody significantly increased conjunctival eosinophil infiltration. Treatment with either antibody during the effector phase did not affect conjunctival eosinophil infiltration. Anti-BTLA antibody treatment during the induction phase reduced the B cell compartment and increased the CD11b-positive cell compartment in splenocytes. Additionally, anti-BTLA treatment upregulated IL-4 and IL-10 production of splenocytes stimulated by RW. CONCLUSIONS: BTLA regulated the development of EC possibly by downregulating Th2 cytokine production and adjusting the compartments of immunocompetent cells. The regulation of EC by BTLA may be mediated by BTLA ligands other than HVEM.

Short ragweed pollen triggers allergic inflammation through Toll-like receptor 4-dependent thymic stromal lymphopoietin/OX40 ligand/OX40 signaling pathways.

BACKGROUND: Allergic diseases affect a large population. Pollen, an ubiquitous allergen, is the trigger of seasonal rhinitis, conjunctivitis, and asthma, as well as an exacerbating factor of atopic dermatitis. However, the underlying mechanism by which pollen induces thymic stromal lymphopoietin (TSLP)-triggered allergic inflammation through epithelial innate immunity is largely unknown. OBJECTIVE: We sought to explore whether short ragweed (SRW) pollen induces TSLP/OX40 ligand (OX40L)/OX40 signaling through Toll-like receptor (TLR) 4-dependent pathways in patients with allergic disease. METHODS: Three models were used for this study, a well-characterized murine model of allergic conjunctivitis induced by SRW pollen, a topical challenge model on the murine ocular surface, and a culture model of primary human corneal epithelium exposed to aqueous extract of defatted SRW pollen (SRWe). RESULTS: The topical challenges with SRW pollen generated typical allergic conjunctivitis in BALB/c mice. Clinical signs, stimulated TSLP/OX40L/OX40 signaling, and T(H)2 cytokine levels in the ocular mucosa and draining cervical lymph nodes were significantly reduced or eliminated in TLR4-deficient (Tlr4-d) or myeloid differentiation primary response gene 88 (MyD88) knockout (MyD88(-/-)) mice compared with those seen in their wild-type littermates. SRWe stimulated TSLP production by ocular epithelia in wild-type but not Tlr4-d or MyD88(-/-) mice. SRWe-stimulated TSLP was blocked by TLR4 antibody and nuclear factor κB inhibitor in murine and human corneal epithelia. CONCLUSION: For the first time, we have shown that SRW pollen, acting as a functional TLR4 agonist, initiates TLR4-dependent TSLP/OX40L/OX40 signaling, which triggers T(H)2-dominant allergic inflammation. These findings shed light on the understanding of mucosal epithelial innate immunity and create new therapeutic targets to cure allergic diseases.

Aldose reductase inhibition suppresses airway inflammation.

Airway inflammation induced by reactive oxygen species (ROS)-mediated activation of redox-sensitive transcription factors is the hallmark of asthma, a prevalent chronic respiratory disease. In various cellular and animal models, we have recently demonstrated that, in response to multiple stimuli, aldose reductase (AKR1B1) regulates the inflammatory signals via NF-kappa B activation. Since NF-κB activation is implicated in asthma pathogenesis, we investigated whether AKR1B1 inhibition could prevent ovalbumin (Ova)- and ragweed pollen extract (RWE)-induced airway inflammation and hyper-responsiveness in mice models and tumor necrosis factor-alpha (TNF-α)-, lipopolysachharide (LPS)- and RWE-induced cytotoxic and inflammatory signals in primary human small airway epithelial cells (SAEC). Sensitization and challenge with Ova or RWE caused airway inflammation and production of inflammatory cytokines, accumulation of eosinophils in airways and sub-epithelial regions, mucin production in the bronchoalveolar lavage fluid, airway hyperresponsiveness, elevated IgE levels and release of Th2 cytokines in the airway and treatment with AKR1B1 inhibitors markedly reduced these pathological changes in mice. In SAEC, treatment with TNF-α, LPS or RWE induced apoptosis, reactive oxygen species generation, synthesis of inflammatory markers IL-6, IL-8, and PGE2 and activation of NF-κB and AP-1. Pharmacological inhibition prevented these changes suggesting that AKR1B1 mediates ROS induced inflammation in small airway epithelial cells. Our results indicate that AKR1B1 inhibitors may offer a novel therapeutic approach to treat inflammatory airway diseases such as asthma.

Allergen-specific T cell responses to immunotherapy monitored by CD154 and intracellular cytokine expression.

BACKGROUND: A sensitive measurement of low numbers of intracellular cytokine-expressing antigen-specific T cells from peripheral blood mononuclear cells (PBMC) is possible using CD154 as a marker of recently activated T cells. This technique may have potential for monitoring peripheral blood T cell responses to immunotherapy. OBJECTIVE: To evaluate the applicability of this method for measuring changes in cytokine production by allergen-specific T cells in a clinical trial setting. METHODS: Ex vivo ragweed-specific CD154 and intracellular cytokine expression were evaluated using a subset of subjects in an environmental chamber study of allergic rhinitis immunotherapy. PBMC were collected and cryopreserved from Amb a 1-immunostimulatory oligodeoxynucleotide conjugate (AIC)-treated (n=17) and placebo-treated (n=15) ragweed-allergic subjects both after pre- and post-treatment ragweed exposures. In vitro allergen-stimulated CD3(+)CD4(+)CD154(+) T cell intracellular IL-4, IL-5, IL-13, and IFN-gamma expression were evaluated by flow cytometry. RESULTS: Compared with the T helper type 2 (Th2) cytokine expression measured after pre-treatment ragweed exposures, placebo-treated subjects demonstrated a significantly elevated ragweed- and Amb a 1-specific T cell IL-4 and IL-13 co-expression (P=0.005 and P=0.022, respectively) and a significantly elevated ragweed-specific IL-5 expression (P<0.001) following post-treatment ragweed exposures. In contrast, AIC-treated subjects demonstrated no increases in allergen-specific Th2 cytokine expression following post-treatment ragweed exposures. IFN-gamma expression remained low and un-changed in both groups. Subject reported total nasal symptom scores demonstrated modest but significant correlations with Amb a 1- and ragweed-stimulated intracellular Th2 cytokine responses. CONCLUSION: Combined CD154 and intracellular cytokine staining in PBMC can be used to sensitively monitor changes in antigen-specific T cell subset frequencies in clinical studies. Antigen-specific cytokine expression moderately correlated with the reported levels of allergic symptoms.

Involvement of A1 adenosine receptors in altered vascular responses and inflammation in an allergic mouse model of asthma.

Poor lung function and respiratory disorders like asthma have a positive correlation with the development of adverse cardiovascular events. Increased adenosine levels are associated with lung inflammation that could lead to altered vascular responses and systemic inflammation. We hypothesized that asthmatic lung inflammation has systemic effects through A(1) adenosine receptors (A(1)AR) and investigated the effects of aerosolized adenosine on vascular reactivity and inflammation, using A(1)AR knockout (A(1)KO) and corresponding wild-type (A(1)WT) mice that were divided into three experimental groups each: control (CON), allergen sensitized and challenged (SEN), and SEN + aerosolized adenosine (SEN + AD). Animals were sensitized with ragweed (200 microg ip; days 1 and 6), followed by 1% ragweed aerosol challenges (days 11 to 13). On day 14, the SEN + AD groups received one adenosine aerosol challenge (6 mg/ml) for 2 min, and aortae were collected on day 15. 5'-N-ethylcarboxamidoadenosine (NECA; nonselective adenosine analog) induced concentration-dependent aortic relaxation in the A(1)WT CON group, which was impaired in the A(1)WT SEN and SEN + AD groups. All groups of A(1)KO mice showed similar (no significant difference) concentration-dependent relaxation to NECA. The A(1)WT SEN and SEN + AD groups had a significantly higher contraction to selective A(1) agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) compared with the CON group. Western blot data showed that aortic A(1)AR expression was significantly increased in WT SEN and SEN + AD mice compared with CON mice. Gene expression of ICAM-1 and IL-5 was significantly increased in allergic A(1)WT aorta and were undetected in the A(1)KO groups. A(1)WT allergic mice had significantly higher airway hyperresponsiveness (enhanced pause) to NECA, with adenosine aerosol further enhancing it. In conclusion, allergic A(1)WT mice showed altered vascular reactivity, increased airway hyperresponsiveness, and systemic inflammation. These data suggest that A(1)AR is proinflammatory systemically in this model of allergic asthma.

Bone marrow stromal cells use TGF-beta to suppress allergic responses in a mouse model of ragweed-induced asthma.

Bone marrow stromal cells [BMSCs; also known as mesenchymal stem cells (MSCs)] effectively suppress inflammatory responses in acute graft-versus-host disease in humans and in a number of disease models in mice. Many of the studies concluded that BMSC-driven immunomodulation is mediated by the suppression of proinflammatory Th1 responses while rebalancing the Th1/Th2 ratio toward Th2. In this study, using a ragweed induced mouse asthma model, we studied if BMSCs could be beneficial in an allergic, Th2-dominant environment. When BMSCs were injected i.v. at the time of the antigen challenge, they protected the animals from the majority of asthma-specific pathological changes, including inhibition of eosinophil infiltration and excess mucus production in the lung, decreased levels of Th2 cytokines (IL-4, IL-5, and IL-13) in bronchial lavage, and lowered serum levels of Th2 immunoglobulins (IgG1 and IgE). To explore the mechanism of the effect we used BMSCs isolated from a variety of knockout mice, performed in vivo blocking of cytokines and studied the effect of asthmatic serum and bronchoalveolar lavage from ragweed challenged animals on the BMSCs in vitro. Our results suggest that IL-4 and/or IL-13 activate the STAT6 pathway in the BMSCs resulting in an increase of their TGF-beta production, which seems to mediate the beneficial effect, either alone, or together with regulatory T cells, some of which might be recruited by the BMSCs. These data suggest that, in addition to focusing on graft-versus-host disease and autoimmune diseases, allergic conditions--specifically therapy resistant asthma--might also be a likely target of the recently discovered cellular therapy approach using BMSCs.

Pollen-induced oxidative stress influences both innate and adaptive immune responses via altering dendritic cell functions.

It has been demonstrated that pollen grains contain NAD(P)H oxidases that induce oxidative stress in the airways, and this oxidative insult is critical for the development of allergic inflammation in sensitized mice. On the basis of this observation, we have examined whether pollen grain exposure triggers oxidative stress in dendritic cells (DCs), altering their functions. To test this hypothesis, human monocyte-derived DCs were treated with ragweed pollen grains. Our findings show that exposure to pollen grains induces an increase in the intracellular levels of reactive oxygen species in DCs. Our data also indicate that besides the NAD(P)H oxidases, other component(s) of pollen grains contributes to this phenomenon. Elevated levels of intracellular reactive oxygen species triggered the production of IL-8 as well as proinflammatory cytokines, such as TNF-alpha and IL-6. Treatment with pollen grains initiated the maturation of DCs, strongly upregulated the membrane expression of CD80, CD86, CD83, and HLA-DR, and caused only a slight increase in the expression of CD40. The pollen-treated DCs induced the development of naive T lymphocytes toward effector T cells with a mixed profile of cytokine production. Antioxidant inhibited both the phenotypic and functional changes of DCs, underlining the importance of oxidative stress in these processes. Collectively, these data show that pollen exposure-induced oxidative stress may contribute to local innate immunity and participate in the initiation of adaptive immune responses to pollen Ags.

Participation of CD11b and F4/80 molecules in the conjunctival eosinophilia of experimental allergic conjunctivitis.

BACKGROUND: CD11b and F4/80 are macrophage surface markers. How these molecules participate in allergic eosinophil infiltration remains unclear. We examined the roles CD11b and F4/80 play in the conjunctival eosinophil infiltration associated with experimental allergic conjunctivitis. METHODS: Ragweed-immunized BALB/c mice were challenged with ragweed in eye drops to induce conjunctival eosinophil infiltration. The effect of challenge on conjunctival CD11b+ and F4/80+ cell numbers was determined by immunohistochemistry. In the same model, blocking anti-CD11b and anti-F4/80 Abs were injected intraperitoneally during the induction or the effector phase, or subconjunctivally 2 h before challenge, to determine their effect on challenge-induced conjunctival eosinophilia. To examine whether eosinophils express CD11b and F4/80 molecules, splenocytes from IL-5 gene-electroporated mice were subjected to flow cytometric analysis. To clarify the involvement of CD11b and F4/80 in conjunctival eosinophil infiltration, mice were intraperitoneally injected with anti-CD11b and anti-F4/80 Abs and then subconjunctivally injected with eotaxin to induce conjunctival eosinophilia. RESULTS: Ragweed challenge elevated conjunctival CD11b+ and F4/80+ cell numbers. Systemic anti-CD11b and anti-F4/80 Ab treatments during the effector phase, but not in either the induction phase or the local injection of Ab, suppressed conjunctival eosinophil infiltration in ragweed-induced conjunctivitis. Most splenic eosinophils from IL-5 gene-introduced mice expressed CD11b and F4/80. Systemic anti-CD11b and anti-F4/80 Ab treatment suppressed conjunctival eosinophilia induced by subconjunctival eotaxin injection. CONCLUSIONS: CD11b and F4/80 appear to participate in conjunctival eosinophil infiltration in allergic conjunctivitis. Their involvement in conjunctival eosinophilia appears to be due to their expression on eosinophils rather than on macrophages.