Cutaneous antigen priming via gene gun leads to skin-selective Th2 immune-inflammatory responses

It is becoming increasingly evident that the compartmentalization of immune responses is governed, in part, by tissue-selective homing instructions imprinted during T cell differentiation. In the context of allergic diseases, the fact that "disease" primarily manifests in particular tissue sites, despite pervasive allergen exposure, supports this notion. However, whether the original site of Ag exposure distinctly privileges memory Th2 immune-inflammatory responses to the same site, while sparing remote tissue compartments, remains to be fully investigated. We examined whether skin-targeted delivery of plasmid DNA encoding OVA via gene-gun technology in mice could generate allergic sensitization and give rise to Th2 effector responses in the skin as well as in the lung upon subsequent Ag encounter. Our data show that cutaneous Ag priming induced OVA-specific serum IgE and IgG1, robust Th2-cytokine production, and late-phase cutaneous responses and systemic anaphylactic shock upon skin and systemic Ag recall, respectively. However, repeated respiratory exposure to aerosolized OVA failed to instigate airway inflammatory responses in cutaneous Ag-primed mice, but not in mice initially sensitized to OVA via the respiratory mucosa. Importantly, these contrasting airway memory responses correlated with the occurrence of Th2 differentiation events at anatomically separate sites: indeed cutaneous Ag priming resulted in Ag-specific proliferative responses and Th2 differentiation in skin-, but not thoracic-, draining lymph nodes. These data indicate that Ag exposure to the skin leads to Th2 differentiation within skin-draining lymph nodes and subsequent Th2 immunity that is selectively manifested in the skin.     

B7RP-1 is not required for the generation of Th2 responses in a model of allergic airway inflammation but is essential for the induction of inhalation tolerance

The recently described ICOS-B7RP-1 costimulatory pathway has been implicated in the generation of effector Th2 responses and, hence, has become an attractive therapeutic target for allergic diseases. In the present study, we used B7RP-1-deficient mice to investigate the role of B7RP-1 in the generation and maintenance of Th2 responses in a model of mucosal allergic airway inflammation. We found that exposure of B7RP-1 knockout mice to aerosolized OVA in the context of GM-CSF leads to airway eosinophilic inflammation. This response was long lasting because rechallenge of mice with the same Ag recapitulated airway eosinophilia. Moreover, significant expression of T1/ST2 on T cells and production of Th2-affiliated cytokines (IL-5, IL-4, and IL-13) and Igs (IgE and IgG1) conclusively demonstrate the generation of a Th2 response in the absence of B7RP-1. In addition, expression of two major Th2-associated costimulatory molecules-CD28 and ICOS-indicates T cell activation in the absence of B7RP-1 signaling. Finally, B7RP-1 knockout mice are resistant to the induction of inhalation tolerance as indicated by the sustained eosinophilia in the lung and IL-5 production. In summary, our results demonstrate that in a model of mucosal allergic sensitization, the ICOS-B7RP-1 pathway is redundant for the generation of Th2 responses but essential for the induction of inhalation tolerance.     

Transient corticosteroid treatment permanently amplifies the Th2 response in a murine model of asthma

Corticosteroids (CS) remain the most efficacious pharmacotherapeutic option for the management of asthma. Although the acute anti-inflammatory effects of CS treatment have been amply documented both clinically and experimentally, recent human data intimate that exposure to CS may be associated with retrograde immune phenomena, including enhanced synthesis of IgE in vivo and elevated Th2 cytokine production in vitro. We have investigated the long-term immunologic effects of CS treatment in a murine model of allergic airway inflammation. CS treatment during initial exposure to OVA or upon long-term Ag rechallenge remarkably attenuated eosinophilic airway inflammation and airway hyperresponsiveness. Interestingly, however, Th2 cytokine production by cultured splenocytes from CS-treated mice was significantly elevated, while IFN-gamma synthesis was depressed. Moreover, mice rechallenged with OVA several weeks after CS intervention during allergic sensitization not only developed airway inflammation, but also exhibited enhanced Th2 cytokine production in lymphoid tissues and OVA-specific IgE in serum. This amplification of the systemic immune response was associated with an intact APC compartment during CS-conditioned sensitization to OVA. These data indicate that immune processes underlying the allergic phenotype remain impervious to CS treatment and raise the possibility that treatment with CS during sensitization may amplify elements of the allergen-specific immune response.     

A critical role for C5L2 in the pathogenesis of experimental allergic asthma

The complement fragment C5a plays dual roles in the development of experimental allergic asthma. It protects from pulmonary allergy by a regulatory effect on dendritic cells during allergen sensitization, but is proallergic during the effector phase. C5a can bind to two distinct receptors (i.e., C5a receptor and C5a receptor-like 2 [C5L2]). The functional role of C5L2 in vivo remains enigmatic. In this study, we show in two models of OVA- and house dust mite (HDM)-induced experimental allergic asthma that C5L2-deficient mice are protected from the development of airway hyperresponsiveness, Th2 cytokine production, eosinophilic airway inflammation, serum IgE, or mucus production. Surprisingly, HDM-induced experimental asthma in C5L2-deficient mice was associated with increased pulmonary IL-17A production and increased airway neutrophil numbers. To directly assess the role of C5L2 on myeloid dendritic cells (mDCs) during allergen sensitization, we performed single or repeated adoptive transfers of C5L2-deficient mDCs into wild-type mice. HDM-pulsed C5L2-deficient mDCs induced strong Th2 cytokine production, which was associated with marked IFN-γ and IL-17A production, decreased eosinophil numbers, and reduced IgE production as compared with HDM-pulsed mDCs from wild-type mice. HDM stimulation of C5L2(-/-) mDCs in vitro resulted in production of Th17-promoting cytokine IL-23, which was absent in wild-type mDCs. Our findings suggest that C5L2 acts at the mDC/T cell interface to control the development of Th1 and Th17 cells in response to airway HDM exposure. Furthermore, it drives Th2 immune responses independent of mDCs, suggesting a complex role for C5L2 in the development of experimental allergic asthma.     

Poly(ADP-ribose) polymerase-1 inhibition prevents eosinophil recruitment by modulating Th2 cytokines in a murine model of allergic airway inflammation: a potential specific effect on IL-5

We recently used a murine model of allergic airway inflammation to show that poly(ADP-ribose) polymerase-1 (PARP-1) plays an important role in the pathogenesis of asthma-related lung inflammation. In this study, we show that PARP-1 inhibition, by a novel inhibitor (TIQ-A) or by gene deletion, prevented eosinophilic infiltration into the airways of OVA-challenged mice. Such impairment of eosinophil recruitment appeared to take place after IgE production. OVA challenge of wild-type mice resulted in a significant increase in IL-4, IL-5, IL-10, IL-13, and GM-CSF secretions. Although IL-4 production was moderately affected in OVA-challenged PARP-1(-/-) mice, the production of IL-5, IL-10, IL-13, and GM-CSF was completely inhibited in ex vivo OVA-challenged lung cells derived from these animals. A single TIQ-A injection before OVA challenge in wild-type mice mimicked the latter effects. The marked effect PARP-1 inhibition exerted on mucus production corroborated the effects observed on the Th2 response. Although PARP-1 inhibition by gene knockout increased the production of the Th1 cytokines IL-2 and IL-12, the inhibition by TIQ-A exerted no effect on these two cytokines. The failure of lung cells derived from OVA-challenged PARP-1(-/-) mice to synthesize GM-CSF, a key cytokine in eosinophil recruitment, was reestablished by replenishment of IL-5. Furthermore, intranasal administration of IL-5 restored the impairment of eosinophil recruitment and mucus production in OVA-challenged PARP-1(-/-) mice. The replenishment of either IL-4 or IgE, however, did not result in such phenotype reversals. Altogether, these results suggest that PARP-1 plays a critical role in eosinophil recruitment by specifically regulating the cascade leading to IL-5 production.     

In vivo IL-10 gene delivery suppresses airway eosinophilia and hyperreactivity by down-regulating APC functions and migration without impairing the antigen-specific systemic immune response in a mouse model of allergic airway inflammation

IL-10 is an immunosuppressive cytokine. Although previous studies have reported that exogenous delivery of IL-10 reduced airway inflammation in experimental allergic airway inflammation, the mechanism of action has not been fully clarified. In this report, we elucidated a mechanism of action of IL-10 in vivo. BALB/c mice were immunized and aerosol challenged with OVA-Ag. We delivered the IL-10 gene to the mice before systemic sensitization or during aerosol Ag challenge by administering an IL-10-producing plasmid vector. Not only presensitization delivery of IL-10, as reported, but also delivery during inflammation strongly suppressed the development of airway eosinophilia and hyperreactivity. Presensitization delivery suppressed the Ag-specific Th2-type immune response in both the lung and spleen. In contrast, delivery in the effector phase suppressed the Th2 response only in the lung, whereas that in the spleen was not affected. IL-10 gene delivery did not induce the development of a regulatory phenotype of T cells or dendritic cells; rather, it suppressed the overall functions of CD11c(+) APCs of the lung such as Ag-presenting capacity, cytokine production, and transportation of OVA-Ag to lymph nodes, thus attenuating Th2-mediated allergic airway inflammation. Further, IL-10 revealed a distinct immunosuppressive effect in the presence of Ag and APCs. These results suggest that suppression of APC function in the lung, the site of immune response, played a critical role in the IL-10-mediated suppression of Ag-induced airway inflammation and hyperreactivity. Therefore, if delivered selectively, IL-10 could site specifically suppress the Ag-specific immune response without affecting systemic immune responses.     

IL-12-dependent vascular cell adhesion molecule-1 expression contributes to airway eosinophilic inflammation in a mouse model of asthma-like reaction

Bronchial-alveolar eosinophilic inflammation is among the characteristic pathological changes in asthma, which has been shown to be correlated with type 2 cytokine and chemokine production. Exogenous IL-12 has been found to be inhibitory for pulmonary eosinophilia in reported studies. Using a murine asthma-like model induced by OVA, we found in the present study that IL-12 gene knockout (KO) mice showed substantially reduced airway recruitment of eosinophils compared with wild-type control mice following OVA sensitization/challenge, although the levels of circulating eosinophils were comparable in these two groups of mice. Cytokine analysis showed Ag-driven Th1 (IFN-gamma) and Th2 (IL-4, IL-5, IL-10, and IL-13) cytokine production by CD4 T cells from local draining lymph nodes and spleen. Similarly, local eotaxin production was comparable in wild-type and IL-12 KO mice. In contrast, immunohistochemical analysis showed that the expression of VCAM-1 on the lung endothelium of IL-12 KO mice was dramatically less than that in wild-type mice. Furthermore, administration of rIL-12 at the stage of sensitization and challenge with OVA restored airway eosinophilia and VCAM-1 expression in IL-12 KO mice. The results suggest that endogenous IL-12 contributes to the recruitment of eosinophils into airways observed in asthma, possibly via enhancement of the expression of VCAM-1 on local vascular endothelial cells.     

IFN-γ-mediated efficacy of allergen-free immunotherapy using mycobacterial antigens and CpG-ODN

Epidemiological and experimental evidence supports the notion that microbial infections that are known to induce Th1-type immune responses can suppress Th2 immune responses, which are characteristics of allergic disorders. However, live microbial immunization might not be feasible for human immunotherapy. Here, we evaluated whether induction of Th1 immunity by the immunostimulatory sequences of CpG-oligodeoxynucleotides (CpG-ODN), with or without culture filtrate proteins (CFP), from Mycobacterium tuberculosis would suppress ongoing allergic lung disease. Presensitized and ovalbumin (OVA)-challenged mice were treated subcutaneously with CpG, or CpG in combination with CFP (CpG/CFP). After 15 days of treatment, airway inflammation and specific T- and B-cell responses were determined. Cell transfer experiments were also performed. CpG treatment attenuated airway allergic disease; however, the combination CpG/CFP treatment was significantly more effective in decreasing airway hyperresponsiveness, eosinophilia and Th2 response. When an additional intranasal dose of CFP was given, allergy was even more attenuated. The CpG/CFP therapy also reduced allergen-specific IgG1 and IgE antibodies and increased IgG2a. Transfer of spleen cells from mice immunized with CpG/CFP also reduced allergic lung inflammation. CpG/CFP treatment induced CFP-specific production of IFN-γ and IL-10 by spleen cells and increased production of IFN-γ in response to OVA. The essential role of IFN-γ for the therapeutic effect of CpG/CFP was evidenced in IFN-γ knockout mice. These results show that CpG/CFP treatment reverses established Th2 allergic responses by an IFN-γ-dependent mechanism that seems to act both locally in the lung and systemically to decrease allergen-specific Th2 responses.     

Chronic exposure to innocuous antigen in sensitized mice leads to suppressed airway eosinophilia that is reversed by granulocyte macrophage colony-stimulating factor

In this study we investigated the impact of chronic allergen exposure on airway inflammation and humoral responses in sensitized mice. We observed marked eosinophilia in the bronchoalveolar lavage, lung tissue, and peripheral blood after 2 wk of exposure. In contrast, eosinophilia was markedly reduced by 3 wk and completely resolved by 4 wk of exposure, despite the continued presence of Ag. Decreases in airway eosinophilia were associated with a robust humoral response. We observed that levels of OVA-specific IgE, IgG1, and IgG2a increased during the course of exposure. To assess whether continuous exposure to Ag impacts the ability of the lung to respond to subsequent Ag challenge, mice were exposed to either 2 or 4 wk of OVA in the context of GM-CSF. All groups were then rested for 28 days and exposed to OVA on three consecutive days. We observed a significant decrease in airway eosinophilia and IL-5 expression in the bronchoalveolar lavage and serum in mice initially exposed to 4 wk of OVA, compared with animals exposed to 2 wk only. However, in both groups expression of B7.2 on dendritic cells as well as CD25, CD69, and T1/ST2 on CD4(+) T cells was enhanced, suggesting immune activation. Delivery of rGM-CSF fully restored airway eosinophilia. This study shows that exposure to innocuous Ag alone does not lead to persistent eosinophilic airway inflammation, but rather to abrogated eosinophilia. This suppression can be reversed by GM-CSF.     

Proteinase-activated receptor-2 promotes allergic sensitization to an inhaled antigen through a TNF-mediated pathway

The reason why particular inhaled Ags induce allergic sensitization while others lead to immune tolerance is unclear. Along with a genetic predisposition to atopy, intrinsic characteristics of these Ags must be important. A common characteristic of many allergens is that they either possess proteinase activity or are inhaled in particles rich in proteinases. Many allergens, such as house dust mite and cockroach allergens, have the potential to activate the proteinase-activated receptor (PAR)-2. In this study, we report that PAR-2 activation in the airways at the same time as exposure to inhaled Ags induces allergic sensitization, whereas exposure to Ag alone induces tolerance. BALB/c mice were administered OVA with a PAR-2 activating peptide intranasally. Upon allergen re-exposure mice developed airway inflammation and airway hyperresponsiveness, as well as OVA-specific T cells with a Th2 cytokine profile when restimulated with OVA in vitro. Conversely, mice given OVA alone or OVA with a PAR-2 control peptide developed tolerance. These tolerant mice did not develop airway inflammation or airway hyperresponsiveness, and developed OVA-specific T cells that secreted high levels of IL-10 when restimulated with OVA in vitro. Furthermore, pulmonary dendritic cell trafficking was altered in mice following intranasal PAR-2 activation. Finally, we showed that PAR-2-mediated allergic sensitization was TNF-dependent. Thus, PAR-2 activation in the airways could be a critical factor in the development of allergic sensitization following mucosal exposure to allergens with serine proteinase activity. Interfering with this pathway may prove to be useful for the prevention or treatment of allergic diseases.     

Nitrogen dioxide promotes allergic sensitization to inhaled antigen

Allergen sensitization and allergic airway disease are likely to come about through the inhalation of Ag with immunostimulatory molecules. However, environmental pollutants, including nitrogen dioxide (NO2), may promote adaptive immune responses to innocuous Ags that are not by themselves immunostimulatory. We tested in C57BL/6 mice whether exposure to NO2, followed by inhalation of the innocuous protein Ag, OVA, would result in allergen sensitization and the subsequent development of allergic airway disease. Following challenge with aerosolized OVA alone, mice previously exposed via inhalation to NO2 and OVA developed eosinophilic inflammation and mucus cell metaplasia in the lungs, as well as OVA-specific IgE and IgG1, and Th2-type cytokine responses. One hour of exposure to 10 parts per million NO2 increased bronchoalveolar lavage fluid levels of total protein, lactate dehydrogenase activity, and heat shock protein 70; promoted the activation of NF-kappaB by airway epithelial cells; and stimulated the subsequent allergic response to Ag challenge. Furthermore, features of allergic airway disease were not induced in allergen-challenged TLR2-/- and MyD88-/- mice exposed to NO2 and aerosolized OVA during sensitization. These findings offer a mechanism whereby allergen sensitization and asthma may result under conditions of high ambient or endogenous NO2 levels.     

Long-lived Th2 memory in experimental allergic asthma

Although life-long immunity against pathogens is beneficial, immunological memory responses directed against allergens are potentially harmful. Because there is a paucity of information about Th2 memory cells in allergic disease, we established a model of allergic asthma in BALB/c mice to explore the generation and maintenance of Th2 memory. We induced disease without the use of adjuvants, thus avoiding Ag depots, and found that unlike allergic asthma in mice immunized with adjuvant, immunizing with soluble and aerosol OVA resulted in pathological lung lesions resembling human disease. To test memory responses we allowed mice with acute disease to recover and then re-exposed them to aerosol OVA a second time. Over 400 days later these mice developed OVA-dependent eosinophilic lung inflammation, airway hyperresponsiveness, mucus hypersecretion, and IgE. Over 1 year after recuperating from acute disease, mice had persistent lymphocytic lung infiltrates, Ag-specific production of IL-4 and IL-5 from spleen and lung cells in vitro, and elevated IgG1. Moreover, when recuperated mice were briefly aerosol challenged, we detected early expression of Th2 cytokine RNA in lungs. Taken together, these data demonstrate the presence of long-lived Th2 memory cells in spleen and lungs involved in the generation of allergic asthma upon Ag re-exposure.     

Antigen-sensitized CD4+CD62Llow memory/effector T helper 2 cells can induce airway hyperresponsiveness in an antigen free setting

Background

Airway hyperresponsiveness (AHR) is one of the most prominent features of asthma, however, precise mechanisms for its induction have not been fully elucidated. We previously reported that systemic antigen sensitization alone directly induces AHR before development of eosinophilic airway inflammation in a mouse model of allergic airway inflammation, which suggests a critical role of antigen-specific systemic immune response itself in the induction of AHR. In the present study, we examined this possibility by cell transfer experiment, and then analyzed which cell source was essential for this process.

Methods

BALB/c mice were immunized with ovalbumin (OVA) twice. Spleen cells were obtained from the mice and were transferred in naive mice. Four days later, AHR was assessed. We carried out bronchoalveolar lavage (BAL) to analyze inflammation and cytokine production in the lung. Fluorescence and immunohistochemical studies were performed to identify T cells recruiting and proliferating in the lung or in the gut of the recipient. To determine the essential phenotype, spleen cells were column purified by antibody-coated microbeads with negative or positive selection, and transferred. Then, AHR was assessed.

Results

Transfer of spleen cells obtained from OVA-sensitized mice induced a moderate, but significant, AHR without airway antigen challenge in naive mice without airway eosinophilia. Immunization with T helper (Th) 1 elicited antigen (OVA with complete Freund''s adjuvant) did not induce the AHR. Transferred cells distributed among organs, and the cells proliferated in an antigen free setting for at least three days in the lung. This transfer-induced AHR persisted for one week. Interleukin-4 and 5 in the BAL fluid increased in the transferred mice. Immunoglobulin E was not involved in this transfer-induced AHR. Transfer of in vitro polarized CD4⁺ Th2 cells, but not Th1 cells, induced AHR. We finally clarified that CD4⁺CD62L^low memory/effector T cells recruited in the lung and proliferated, thus induced AHR.

Conclusion

These results suggest that antigen-sensitized memory/effector Th2 cells themselves play an important role for induction of basal AHR in an antigen free, eosinophil-independent setting. Therefore, regulation of CD4⁺ T cell-mediated immune response itself could be a critical therapeutic target for allergic asthma.     

An intranasal selective antisense oligonucleotide impairs lung cyclooxygenase-2 production and improves inflammation,but worsens airway function,in house dust mite sensitive mice

Background

Despite its reported pro-inflammatory activity, cyclooxygenase (COX)-2 has been proposed to play a protective role in asthma. Accordingly, COX-2 might be down-regulated in the airway cells of asthmatics. This, together with results of experiments to assess the impact of COX-2 blockade in ovalbumin (OVA)-sensitized mice in vivo, led us to propose a novel experimental approach using house dust mite (HDM)-sensitized mice in which we mimicked altered regulation of COX-2.

Methods

Allergic inflammation was induced in BALBc mice by intranasal exposure to HDM for 10 consecutive days. This model reproduces spontaneous exposure to aeroallergens by asthmatic patients. In order to impair, but not fully block, COX-2 production in the airways, some of the animals received an intranasal antisense oligonucleotide. Lung COX-2 expression and activity were measured along with bronchovascular inflammation, airway reactivity, and prostaglandin production.

Results

We observed impaired COX-2 mRNA and protein expression in the lung tissue of selective oligonucleotide-treated sensitized mice. This was accompanied by diminished production of mPGE synthase and PGE₂ in the airways. In sensitized mice, the oligonucleotide induced increased airway hyperreactivity (AHR) to methacholine, but a substantially reduced bronchovascular inflammation. Finally, mRNA levels of hPGD synthase remained unchanged.

Conclusion

Intranasal antisense therapy against COX-2 in vivo mimicked the reported impairment of COX-2 regulation in the airway cells of asthmatic patients. This strategy revealed an unexpected novel dual effect: inflammation was improved but AHR worsened. This approach will provide insights into the differential regulation of inflammation and lung function in asthma, and will help identify pharmacological targets within the COX-2/PG system.     

Airway activation of formyl peptide receptors inhibits Th1 and Th17 cell responses via inhibition of mediator release from immune and inflammatory cells and maturation of dendritic cells

Formyl peptide receptors (FPRs) are chemoattractant receptors that mediate inflammatory cell responses to infection. Recent evidence indicates that noneosinophilic asthma phenotypes can be developed by both Th1 and Th17 cell responses when exposed to LPS-containing allergens. In this study, we evaluated the effects of airway activation of FPRs by their synthetic agonist, Trp-Lys-Tyr-Met-Val-D-Met (W-peptide), on the development of Th1 and Th17 cell responses in a noneosinophilic asthma mouse model. A noneosinophilic asthma mouse model was generated by intranasal sensitization with 10 μg of LPS plus 75 μg of OVA on days 0, 1, 2, and 7. Mice were then challenged with 50 μg of OVA alone on days 14, 15, 21, and 22. W-peptide was administered during the sensitization period, and immune and inflammatory responses were evaluated after OVA challenge. Lung inflammation after OVA challenge was partly abolished by airway activation of FPRs during sensitization. Maturation of dendritic cells (DCs) and migration of DCs from the lung to lung-draining lymph nodes were inhibited by FPR activation. In addition, airway activation of FPRs inhibited allergen-specific T cell proliferation in the lymph nodes. Production of IL-12 and IL-6 (Th1- and Th17-polarizing cytokines) from lung DCs was decreased by airway activation of FPRs. This effect resulted in the inhibition of allergen-specific Th1 and Th17 cell responses. Airway activation of FPRs during sensitization effectively prevents the development of Th1 and Th17 cell responses induced by LPS-containing allergens via multiple mechanisms, such as inhibition of DC maturation and migration and the production of Th1- and Th7-polarizing cytokines.     

IL-5-induced hypereosinophilia suppresses the antigen-induced immune response via a TGF-beta-dependent mechanism

Although eosinophils play an essential role in allergic inflammation, their role has recently been under controversy. Epidemic studies suggest that hypereosinophilia induced by parasite infection could suppress subsequent Ag sensitization, although the mechanism has not been fully clarified. In this study, we investigated whether eosinophils could suppress the Ag-specific immune response in the airway. BALB/c mice were sensitized and airway challenged with OVA. Systemic hypereosinophilia was induced by delivery of an IL-5-producing plasmid. IL-5 gene delivery suppressed the Ag-specific proliferation and cytokine production of CD4+ T cells in the spleen. IL-5 gene delivery before OVA sensitization significantly suppressed airway eosinophilia and hyperresponsiveness provoked by subsequent OVA airway challenge, while delivery during the OVA challenge did not suppress them. This IL-5-induced immune suppression was abolished in eosinophil-ablated mice, suggesting an essential role of eosinophils. IL-5 treatment increased the production of TGF-beta1 in the spleen, and we demonstrated that the main cellular source of TGF-beta1 production was eosinophils, using eosinophil-ablated mice and depletion study. TGF-beta1, but not IL-5 itself, suppressed the Ag-specific immune response of CD4+ T cells in vitro. Furthermore, IL-5 treatment enhanced phosphorylation of Smad2 in CD4+ T cells. Finally, a TGF-beta type I receptor kinase inhibitor restored this IL-5-induced immune suppression both in vitro and in vivo. These results suggest that IL-5-induced hypereosinophilia could suppress sensitization to Ag via a TGF-beta-dependent mechanism, thus suppressed allergic airway inflammation. Therefore, hypereosinophilia could reveal an immunosuppressive effect in the early stage of Ag-induced immune response.     

IL-11 selectively inhibits aeroallergen-induced pulmonary eosinophilia and Th2 cytokine production

IL-11 is a pleiotropic cytokine that induces tissue remodeling with subepithelial fibrosis when expressed in the airway. Its effects on the Th2-dominated airway inflammation that is characteristic of asthma, however, are poorly understood. To characterize the effects of IL-11 on Th2 tissue inflammation, we compared the inflammatory responses elicited by OVA in sensitized mice in which IL-11 is overexpressed in a lung-specific fashion (CC10-IL-11) with that in transgene- wild-type littermate controls. Transgene- and CC10-IL-11 transgene+ mice had comparable levels of circulating Ag-specific IgE after sensitization. OVA challenge of sensitized transgene- mice caused airway and parenchymal eosinophilic inflammation, Th2 cell accumulation, and mucus hypersecretion with mucus metaplasia. Exaggerated levels of immunoreactive endothelial cell VCAM-1, mucin (Muc) 5ac gene expression and bronchoalveolar lavage and lung IL-4, IL-5, and IL-13 protein and mRNA were also noted. In contrast, OVA challenge in CC10-IL-11 animals elicited impressively lower levels of tissue and bronchoalveolar lavage inflammation, eosinophilia, and Th2 cell accumulation, and significantly lower levels of VCAM-1 and IL-4, IL-5, and IL-13 mRNA and protein. IL-11 did not cause a comparable decrease in mucus hypersecretion, Muc 5ac gene expression, or the level of expression of RANTES, monocyte chemoattractant protein-2, or monocyte chemoattractant protein-3. In addition, IL-11 did not augment IFN-gamma production demonstrating that the inhibitory effects of IL-11 were not due to a shift toward Th1 inflammation. These studies demonstrate that IL-11 selectively inhibits Ag-induced eosinophilia, Th2 inflammation, and VCAM-1 gene expression in pulmonary tissues.     

Lunasin Alleviates Allergic Airway Inflammation while Increases Antigen-Specific Tregs

Lunasin is a naturally occurring peptide isolated from soybeans and has been explored in cancer treatment. Lunasin inhibits NF-κB activation and thus pro-inflammatory cytokine and mediator production in macrophages. In this study we demonstrate that lunasin can effectively suppress allergic airway inflammation in two murine models of asthma. In an OVA+Alum sensitization model, intranasal lunasin treatment at the time of OVA challenges significantly reduced total cells counts in bronchoalveolar lavage (BAL) fluid and eosinophilia, peribronchiolar inflammatory infiltration, goblet cell metaplasia and airway IL-4 production. In an OVA+LPS intranasal sensitization model, lunasin treatment either at the time of sensitization or challenge has similar effects in suppress allergic airway inflammation including significantly reduced total cell and eosinophil counts in BAL fluid, inflammatory gene Fizz1 expression in the lung, and IL-4 production by OVA re-stimulated cells from mediastinal lymph nodes. We further show that intranasal instillation of OVA+lunasin significantly increases OVA-specific regulatory T cell (Treg) accumulation in the lung comparing to OVA only treatment. Taken together, our results suggest lunasin as an anti-inflammatory agent can be potentially used in asthma therapy or as an adjuvant to enhance the induction of antigen-specific Tregs and thus boost the efficacy of allergy immunotherapy.