OVA-induced Allergic Airway Disease Research Articles

Adaptive plasticity of natural interleukin-35-induced regulatory T cells (Tr35) that are required for T-cell immune regulation.

Background: IL-35 potently inhibits immune responses both in vivo and in vitro. However, the specific characteristics of IL-35-producing cells, including their developmental origin, cellular phenotype, and function, are unknown. Methods: By using a novel IL-35 reporter mouse (Ebi3-Dre-Thy1.1) and double transgenic fate-mapping reporter mice (35EbiT-Rosa26-rox-tdTomato reporter mice or Foxp3 fate-mapping system), we tracked and analyzed the differentiation and developmental trajectories of Tr35 cells in vivo. And then we investigated the therapeutic effects of OVA-specific Tr35 cells in an OVA-induced allergic airway disease model. Results: We identified a subset of cells, denoted Tr35 cells, that secrete IL-35 but do not express Foxp3. These cells have high expression of molecules associated with T-cell activation and can inhibit T-cell proliferation in vitro. Our analyses showed that Tr35 cells are a distinct subpopulation of cells that are independent of Tr1 cells. Tr35 cells exhibit a unique gene expression profile and tissue distribution. The presence of Thy1.1 (Ebi3) expression in Tr35 cells indicates their active secretion of IL-35. However, the proportion of ex-Tr35 cells (Thy1.1-) is significantly higher compared to Tr35 cells (Thy1.1+). This suggests that Tr35 cells possess the ability to regulate IL-35 expression rapidly in vivo. Tr35 cells downregulated the expression of the inflammatory cytokines IL-4, IFN-γ and IL-17A. However, once Tr35 cells lost IL-35 expression and became exTr35 cells, the expression of inflammatory cytokines was upregulated. Importantly, our findings indicate that Tr35 cells have therapeutic potential. In an OVA-induced allergic airway disease mouse model, Tr35 cell reinfusion significantly reduced airway hyperresponsiveness and histopathological airway and lung inflammation. Conclusions: We have identified a subset of Tregs, Tr35 cells, that are distinct from Tr1 cells. Tr35 cells can dynamically regulate the secretion of inflammatory cytokines by controlling IL-35 expression to regulate inflammatory immune responses.

A Helminth-Derived Chitinase Structurally Similar to Mammalian Chitinase Displays Immunomodulatory Properties in Inflammatory Lung Disease.

Immunomodulation of airway hyperreactivity by excretory-secretory (ES) products of the first larval stage (L1) of the gastrointestinal nematode Trichuris suis is reported by us and others. Here, we aimed to identify the proteins accounting for the modulatory effects of the T. suis L1 ES proteins and studied six selected T. suis L1 proteins for their immunomodulatory efficacy in a murine OVA-induced allergic airway disease model. In particular, an enzymatically active T. suis chitinase mediated amelioration of clinical signs of airway hyperreactivity, primarily associated with suppression of eosinophil recruitment into the lung, the associated chemokines, and increased numbers of RELMα+ interstitial lung macrophages. While there is no indication of T. suis chitinase directly interfering with dendritic cell activation or antigen presentation to CD4 T cells, treatment of allergic mice with the worm chitinase influenced the hosts' own chitinase activity in the inflamed lung. The three-dimensional structure of the T. suis chitinase as determined by high-resolution X-ray crystallography revealed high similarities to mouse acidic mammalian chitinase (AMCase) but a unique ability of T. suis chitinase to form dimers. Our data indicate that the structural similarities between the parasite and host chitinase contribute to the disease-ameliorating effect of the helminth-derived chitinase on allergic lung inflammation.

B Cell derived IL-4 promotes IL-10 secreting TIM-1+ regulatory B cell expansion and regulates Th2 T cell responses

Abstract TIM-1+ B cells are enriched for IL-10+ B regulatory cells (Bregs). However, TIM-1+ B cells are also enriched for IL-4+ B effector 2 cells (Be2). Tolerogenic α-TIM-1 (RMT1-10) prolongs islet allograft survival (GS) by expanding (IL-10+) Bregs. Interestingly, IL-4KO and IL-4Rα-KO mice are deficient in Bregs and are not responsive to αTIM-1. To establish the importance of IL-4R signaling, and the source of IL-4 for Breg induction, we made tamoxifen (TAM) inducible BALB/c hCD20Cre.ERT2+/− X IL-4Rαfl/fl (B-IL-4RαKO) and hCD20Cre.ERT2+/− X IL-4/13fl/fl mice (B-IL-4KO) to respectively delete IL-4Rα or IL-4/IL-13 in B cells. After TAM, αTIM-1 treatment of alloimmunized B-IL-4RαKO mice had ↓ TIM-1+ B cells (50%), Be2 (50%) and Bregs (40%) vs. IL-4Rαfl/fl littermate controls and a concomittant 33%↑ in IFNγ+ and 33% ↓ in IL-10+ CD4 T cells, and a 20%↑ in IFNγ+ CD8 T cells vs. controls. Finally, α–TIM-1 led to >100d GS in 75% of control mice, but failed to improve GS in B-IL-4RαKO mice (MST 20d, p=0.03). Similarly, TAM treated B-IL-4KO mice had a 3x ↓ in Be2 and Bregs vs. IL-4fl/fl controls, and a 6x drop in IL-4+ CD4 T cells. Importantly, B-IL-4KO mice rejected islets more rapidly (MST 20d) than controls (MST 31d, p=0.04), and α–TIM-1 failed to improve B-IL-4KO GS (MST 17d) vs. controls (MST >100d). In contrast, in Th2 dominant OVA-induced allergic airway disease (AAD), B-IL-4KO mice had 3x decrease in total lymphocyte infiltrate, 5x decrease CD4 T cells and 8x decrease eosinophils in BAL fluid vs. controls. CD4+ T cells from whole lung tissue produced 2x less IL-4 and 3x less IL-5 vs. controls. Hence, IL-4 production by B cells is important for both Breg induction and Th2 polarization and absence of B cell IL-4/IL-13 promotes allograft rejection yet reduces AAD.

Differential Influence on Regulatory B Cells by TH2 Cytokines Affects Protection in Allergic Airway Disease.

The role of regulatory B cells (Bregs) in modulating immune responses and maintaining tolerance are well established. However, how cytokines present during immune responses affect Breg growth and function are not as well defined. Previously, our laboratory reported IL-5- and mCD40L-expressing fibroblast (mCD40L-Fb) stimulation induced IL-10 production from murine B cells. The current study investigated the phenotype and functional relevance of IL-10- producing B cells from this culture. We found IL-5/mCD40L-Fb stimulation induced IL-10 production exclusively from CD5+ splenic B cells of naive mice. After stimulation, the resulting IL-10+ B cells displayed markers of multiple reported Breg phenotypes. Interestingly, when investigating effects of IL-4 (a critical TH2 cytokine) on IL-5/mCD40L-Fb-induced IL-10 production, we found IL-4 inhibited IL-10 production in a STAT6-dependent manner. Upon adoptive transfer, CD5+ B cells previously stimulated with IL-5/mCD40L-Fb were able to reduce development of OVA-induced allergic airway disease in mice. Using B cells from IL-10 mutant mice differentiated by IL-5/mCD40L-Fb, we found protection from allergic airway disease development was dependent on the IL-10 production from the transferred B cells. Bregs have been shown to play crucial roles in the immune tolerance network, and understanding stimuli that modulate their growth and function may be key in development of future treatments for diseases of immune dysregulation.

Vitamin D and allergic airway disease shape the murine lung microbiome in a sex-specific manner

BackgroundVitamin D is under scrutiny as a potential regulator of the development of respiratory diseases characterised by chronic lung inflammation, including asthma and chronic obstructive pulmonary disease. It has anti-inflammatory effects; however, knowledge around the relationship between dietary vitamin D, inflammation and the microbiome in the lungs is limited. In our previous studies, we observed more inflammatory cells in the bronchoalveolar lavage fluid and increased bacterial load in the lungs of vitamin D-deficient male mice with allergic airway disease, suggesting that vitamin D might modulate the lung microbiome. In the current study, we examined in more depth the effects of vitamin D deficiency initiated early in life, and subsequent supplementation with dietary vitamin D on the composition of the lung microbiome and the extent of respiratory inflammation.MethodsBALB/c dams were fed a vitamin D-supplemented or -deficient diet throughout gestation and lactation, with offspring continued on this diet post-natally. Some initially deficient offspring were fed a supplemented diet from 8 weeks of age. The lungs of naïve adult male and female offspring were compared prior to the induction of allergic airway disease. In further experiments, offspring were sensitised and boosted with the experimental allergen, ovalbumin (OVA), and T helper type 2-skewing adjuvant, aluminium hydroxide, followed by a single respiratory challenge with OVA.ResultsIn mice fed a vitamin D-containing diet throughout life, a sex difference in the lung microbial community was observed, with increased levels of an Acinetobacter operational taxonomic unit (OTU) in female lungs compared to male lungs. This effect was not observed in vitamin D-deficient mice or initially deficient mice supplemented with vitamin D from early adulthood. In addition, serum 25-hydroxyvitamin D levels inversely correlated with total bacterial OTUs, and Pseudomonas OTUs in the lungs. Increased levels of the antimicrobial murine ß-defensin-2 were detected in the bronchoalveolar lavage fluid of male and female mice fed a vitamin D-containing diet. The induction of OVA-induced allergic airway disease itself had a profound affect on the OTUs identified in the lung microbiome, which was accompanied by substantially more respiratory inflammation than that induced by vitamin D deficiency alone.ConclusionThese data support the notion that maintaining sufficient vitamin D is necessary for optimal lung health, and that vitamin D may modulate the lung microbiome in a sex-specific fashion. Furthermore, our data suggest that the magnitude of the pro-inflammatory and microbiome-modifying effects of vitamin D deficiency were substantially less than that of allergic airway disease, and that there is an important interplay between respiratory inflammation and the lung microbiome.

TLR2, TLR4 AND MyD88 Mediate Allergic Airway Disease (AAD) and Streptococcus pneumoniae-Induced Suppression of AAD.

BackgroundExposure to non-pathogenic Streptococcus pneumoniae and vaccination are inversely associated with asthma. Studies in animal models demonstrate that airway administration of S. pneumoniae (live or killed), or its vaccines or components, suppresses the characteristic features of asthma in mouse models of allergic airway disease (AAD). These components could be developed into immunoregulatory therapies. S. pneumoniae components are recognized by Toll-like receptors (TLR) 2 and TLR4, and both induce inflammatory cell responses through the adaptor protein myeloid differentiation primary response gene 88 (MyD88). The involvement of TLR2, TLR4 and MyD88 in the pathogenesis of AAD and asthma is incompletely understood, and has not been studied in S. pneumoniae-mediated suppression of AAD. We investigated the role of TLR2, TLR4 and MyD88 in the development of AAD and S. pneumoniae-mediated suppression of AAD.Methods and FindingsOVA-induced AAD and killed S. pneumoniae-mediated suppression of AAD were assessed in wild-type, TLR2-/-, TLR4-/-, TLR2/4-/- and MyD88-/- BALB/c mice. During OVA-induced AAD, TLR2, TLR4 and MyD88 were variously involved in promoting eosinophil accumulation in bronchoalveolar lavage fluid and blood, and T-helper type (Th)2 cytokine release from mediastinal lymph node T cells and splenocytes. However, all were required for the induction of airways hyperresponsiveness (AHR). In S. pneumoniae-mediated suppression of AAD, TLR2, TLR4 and MyD88 were variously involved in the suppression of eosinophilic and splenocyte Th2 responses but all were required for the reduction in AHR.ConclusionsThese results highlight important but complex roles for TLR2, TLR4 and MyD88 in promoting the development of OVA-induced AAD, but conversely in the S. pneumoniae-mediated suppression of AAD, with consistent and major contributions in both the induction and suppression of AHR. Thus, TLR signaling is likely required for both the development of asthma and the suppression of asthma by S. pneumoniae, and potentially other immunoregulatory therapies.

Tregitope-mediated antigen-specific tolerance induction in autoimmune and allergic disease in vivo. (THER5P.831)

Abstract Tregitopes are a novel class of therapeutic compounds that harness the activity of regulatory T cells (Tregs) and represent a promising new approach for the treatment of autoimmune and inflammatory diseases. Tregitopes are Treg epitopes found in IgG that provide beneficial immunomodulatory effects, paralleling those attributed to intravenous immunoglobulin (IVIG), in vitro and in vivo. When APCs present Tregitopes to Tregs, APC expression of MHC II, CD80, and CD86 are decreased; expression of the tolerance-associated marker ILT3 is increased. These results are consistent with reported effects of IVIG (Bayry et al. Blood, 2003, 101:758) and the IgG-derived peptide hCDR1 (Sela et al. Immunology, 2009, 128:395). Tregitopes also cause CD4+CD25+FoxP3+ Treg to expand and produce IL-10 in vitro. Evaluation of Tregitope effects in mouse models of MS (EAE), OVA-induced allergic airway disease, and AAV-mediated gene transfer show that effector T cells are modified in the presence of Tregitopes. In OVA-induced allergic airway disease, we observed significant and reproducible expansion of Tregs in conjunction with decreased airway reactivity comparable to, if not greater than, IVIG. We have additional unpublished evidence demonstrating the antigen specificity of tolerance induction using Tregitopes in conjunction with target antigens. Formulated with or without the target antigen, Tregitopes represent a promising new treatment for human immune-mediated disease.

LF-15 & T7, Synthetic Peptides Derived from Tumstatin, Attenuate Aspects of Airway Remodelling in a Murine Model of Chronic OVA-Induced Allergic Airway Disease

BackgroundTumstatin is a segment of the collagen-IV protein that is markedly reduced in the airways of asthmatics. Tumstatin can play an important role in the development of airway remodelling associated with asthma due to its anti-angiogenic properties. This study assessed the anti-angiogenic properties of smaller peptides derived from tumstatin, which contain the interface tumstatin uses to interact with the αVβ3 integrin.MethodsPrimary human lung endothelial cells were exposed to the LF-15, T3 and T7 tumstatin-derived peptides and assessed for cell viability and tube formation in vitro. The impact of the anti-angiogenic properties on airways hyperresponsiveness (AHR) was then examined using a murine model of chronic OVA-induced allergic airways disease.ResultsThe LF-15 and T7 peptides significantly reduced endothelial cell viability and attenuated tube formation in vitro. Mice exposed to OVA+ LF-15 or OVA+T7 also had reduced total lung vascularity and AHR was attenuated compared to mice exposed to OVA alone. T3 peptides reduced cell viability but had no effect on any other parameters.ConclusionThe LF-15 and T7 peptides may be appropriate candidates for use as novel pharmacotherapies due to their small size and anti-angiogenic properties observed in vitro and in vivo.

Amelioration of ovalbumin-induced allergic airway disease following Der p 1 peptide immunotherapy is not associated with induction of IL-35.

In the present study, we show therapeutic amelioration of established ovalbumin (OVA)-induced allergic airway disease following house dust mite (HDM) peptide therapy. Mice were sensitized and challenged with OVA and HDM protein extract (Dermatophagoides species) to induce dual allergen sensitization and allergic airway disease. Treatment of allergic mice with peptides derived from the major allergen Der p 1 suppressed OVA-induced airway hyperresponsiveness, tissue eosinophilia, and goblet cell hyperplasia upon rechallenge with allergen. Peptide treatment also suppressed OVA-specific T-cell proliferation. Resolution of airway pathophysiology was associated with a reduction in recruitment, proliferation, and effector function of T(H)2 cells and decreased interleukin (IL)-17⁺ T cells. Furthermore, peptide immunotherapy induced the regulatory cytokine IL-10 and increased the proportion of Fox p3⁺ cells among those expressing IL-10. Tolerance to OVA was not associated with increased IL-35. In conclusion, our results provide in vivo evidence for the creation of a tolerogenic environment following HDM peptide immunotherapy, leading to the therapeutic amelioration of established OVA-induced allergic airway disease.

Antigen-specific tolerance induction by Tregitopes in vivo (P4202)

Abstract Modulation of T cell responses provide of new opportunities in the treatment of autoimmune and inflammatory diseases. Tregitopes are regulatory T cell (Treg) epitopes found in IgG that provide beneficial immunomodulatory effects, paralleling effects attributed to IVIG. In this presentation, we will provide evidence that Tregitopes derived from human IgG can reproduce immunomodulatory effects of IVIG in vitro and in vivo. Tregitopes cause CD4+CD25+FoxP3+ Treg to expand and produce IL-10 in vitro, and iTreg are induced in vivo. Induction and functions of Tregs have been examined in in vivo model systems such as D011.10 TCR transgenic mice, transplant of BM12 to C57BL/6, AAV-mediated gene transfer and EAE. Together, the data show that effector T cells, Th17, and Th9 cells are modified in the presence of Tregitopes. In OVA-induced allergic airway disease, we observed significant and reproducible expansion of Tregs in conjunction with decreased airway reactivity comparable to, if not greater than IVIG. We will provide additional unpublished evidence demonstrating the antigen specificity of tolerance induction using Tregitopes in conjunction with target antigens, and discuss the relevance of Tregitopes to the treatment of human immune-mediated diseases. Additionally, Treg epitopes (Tregitopes?) have been identified in other common serum proteins, suggesting that peripheral control of inflammatory signals may in part be due to intrinsic self-protein “off switches".

Type V Collagen–induced Tolerance Prevents Airway Hyperresponsiveness

Type V Collagen–induced Tolerance Prevents Airway Hyperresponsiveness

Tregitope applications to tolerance induction in autoimmune diseases. (116.10)

Abstract Modulation of T cell responses may contribute to the design of new approaches for the treatment of autoimmune and inflammatory diseases. IVIG is one example of a therapy with this effect, and evidence is accumulating that Tregitopes (De Groot et al. Blood, 2008, 112:3303; natural T regulatory epitopes derived from IgG) provide beneficial immunomodulatory effects that parallel the effects of IVIG. In this presentation, we will provide evidence that Tregitope sequences derived from human IgG can reproduce immunomodulatory effects of IVIG in vitro and in vivo. In vitro, Tregitopes activate CD4+CD25+FoxP3+ natural regulatory T cells (nTreg). In vitro and in vivo, Tregitopes cause Tregs to produce IL-10, and to expand, and iTreg are induced. Induction and functions of nTregs have been examined in model systems such as D011.10 TCR transgenic mice, transplant of BM12 to C57BL/6, AAV-mediated gene transfer and EAE. Together, the data show that effector T cells, Th17, and Th9 cells are modified in the presence of Tregitopes. In OVA-induced allergic airway disease, we observed significant and reproducible expansion of Tregs in conjunction with decreased airway reactivity that was comparable to, if not greater than IVIG. We will provide additional unpublished evidence demonstrating the antigen specificity of tolerance induction using Tregitopes in conjunction with target antigens, and discuss the relevance of Tregitopes to the treatment of human immune-mediated diseases.

Inhibition of p38 MAPK Reduces Expression of Vascular Endothelial Growth Factor in Allergic Airway Disease

The p38 mitogen-activated protein kinase (MAPK) appears to play an important role in various pathophysiological responses and has been suggested to be involved in many processes considered critical to the inflammatory response and tissue remodeling. Bronchial asthma is a chronic inflammatory disorder of the airway accompanied by increased vascular permeability. Vascular endothelial growth factor (VEGF) is a potent stimulator of bronchial inflammation, airway remodeling, and physiologic dysregulation that augments antigen sensitization and T-helper type 2 cell (Th2)-mediated inflammation in allergic airway diseases. However, there are little data on the relationship between p38 MAPK signaling and VEGF expression in allergic airway disease. This study aimed to investigate the role of p38 MAPK on the pathogenesis of allergic airway disease, more specifically in VEGF expression. Using ovalbumin (OVA)-inhaled mice and a selective p38 MAPK inhibitor, SB 239063, the involvement of p38 MAPK in allergen-induced VEGF expression in the airway was evaluated. The increases of phosphorylation of p38 MAPK, VEGF protein expression, and vascular permeability in the lung after OVA inhalation were decreased substantially by the administration of SB 239063. In addition, SB 239063 significantly reduced the increase of Th2 cytokines and OVA-specific IgE. The inhibition of p38 MAPK or VEGF signaling prevented and also decreased the increases in the number of inflammatory cells and airway hyperresponsiveness in OVA-induced allergic airway disease. These results indicate that inhibition of p38 MAPK may attenuate allergen-induced airway inflammation and vascular leakage through modulation of VEGF expression in mice.

Bronchial epithelial cells produce IL-5: Implications for local immune responses in the airways

IL-5 is a pleiotropic cytokine that promotes eosinophil differentiation and survival. While naïve bronchial epithelial cells (BEC) produce low levels of IL-5, the role of BEC-derived IL-5 in allergic airway inflammation is unknown. We now show that BEC, isolated from mice with OVA-induced allergic airway disease (AAD), produced elevated levels of IL-5 mRNA and protein as compared to BEC from naïve mice. To determine the contribution of BEC-derived IL-5 to effector responses in the airways, IL-5 deficient bone marrow chimeric mice were generated in which IL-5 expression was restricted to stromal (e.g. BEC) or hematopoietic cells. When subjected to AAD, IL-5 produced by BECs contributed to mucous metaplasia, airway eosinophilia, and OVA-specific IgA levels. Thus, IL-5 production by BEC can impact the microenvironment of the lung, modifying pathologic and protective immune responses in the airways.

Breastmilk from Allergic Mothers Can Protect Offspring from Allergic Airway Inflammation

Breastfeeding is associated with a reduced risk of developing asthma in children. Using a murine model we previously demonstrated that mothers with Th1-type immunity to ovalbumin (OVA) transfer antigen-specific protection from OVA-induced allergic airway disease (AAD) to their offspring. The aim of this study was to evaluate the contribution of breastmilk and maternal B cell immunity from allergic mothers in the vertical transmission of protection from AAD. This was investigated using an adoptive nursing strategy. Naive offspring were nursed by allergic wild-type or B cell-deficient foster mothers with histories of Th2-type immunity to OVA. Following weaning, offspring were immunized with OVA-Al(OH)(3) and challenged with aerosolized OVA to induce AAD. Offspring nursed by wild-type OVA-immune foster mothers demonstrated lower levels of OVA-specific immunoglobulin E, interleukin-5, and airway eosinophilia than progeny nursed by naive control mothers. In contrast, offspring nursed by B cell-deficient OVA-immune foster mothers had similar parameters of OVA-induced AAD as progeny nursed by naive control mothers. These data demonstrate the ability of breastmilk from allergic mothers to protect offspring from AAD was dependent on intact maternal B cell immunity. Nursing alone, when done by wild-type mothers with AAD, was sufficient for offspring to acquire the antigen-specific protective factor(s) from breastmilk.

Change of connexin 37 in allergen-induced airway inflammation

Gap junction channels formed with connexins directly link to the cytoplasm of adjacent cells and have been implicated in intercellular signaling. Connexin 37 (Cx37) is expressed in the gas-exchange region of the lung. Recently, Cx37 has been reported to be involved in the pathogenesis of inflammatory disease. However, no data are available on the role of Cx37 in allergic airway inflammatory disease. In the present study, we used a murine model of ovalbumin (OVA)- induced allergic airway disease and primary murine epithelial cells to examine the change of Cx37 in allergic airway disease. These mice develop the following typical pathophysiological features of asthma: airway hyperresponsiveness, airway inflammation, and increased IL-4, IL-5, IL-13, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, eotaxin, and RANTES levels in lungs. Cx37 protein and mRNA expression were decreased in OVA-induced allergic airway disease. Immunoreactive Cx37 localized in epithelial layers around the bronchioles in control mice, which dramatically disappeared in allergen-induced asthmatic lungs. Moreover, the levels of Cx37 protein in lung tissues showed significantly negative correlations with airway inflammation, airway responsiveness, and levels of Th2 cytokines in lungs. These findings indicate that change of Cx37 may be associated with the asthma phenotype.

Maternal Transmission of Resistance to Development of Allergic Airway Disease

Parental phenotype is known to influence the inheritance of atopic diseases, such as allergic asthma, with a maternal history being a more significant risk factor for progeny than paternal history. We hypothesized that recall Th1- or Th2-type immune responses during pregnancy would result in transfer of maternal factors that would differentially impact development of immune responsiveness in offspring. Following weaning, susceptibility and severity of allergic airway disease (a murine model of human asthma) was evaluated in progeny, disease being elicited by immunization with OVA-Al(OH)(3) and challenge with aerosolized OVA. We found that progeny of mothers with Th1-biased immunity to OVA subjected to recall aerosol challenge during pregnancy had reduced levels of Ag-specific IgE and airway eosinophilia compared with progeny of mothers with Th2-biased immunity to OVA or naive mothers. Interestingly, progeny of mothers with Th1-type immunity to a heterologous albumin, BSA, were not protected from developing OVA-induced allergic airway disease. These findings demonstrated that maternal transfer of protection from development of allergic airway disease to offspring in this model of maternal Th1-type immunity was Ag specific.

Absence of CCR8 does not impair the response to ovalbumin-induced allergic airway disease.

Interaction of chemokines with their specific receptors results in tight control of leukocyte migration and positioning. CCR8 is a chemokine receptor expressed mainly in CD4(+) single-positive thymocytes and Th2 cells. We generated CCR8-deficient mice (CCR8(-/-)) to study the in vivo role of this receptor, and describe in this study the CCR8(-/-) mouse response in OVA-induced allergic airway disease using several models, including an adoptive transfer model and receptor-blocking experiments. All CCR8(-/-) mice developed a pathological response similar to that of wild-type animals with respect to bronchoalveolar lavage cell composition, peripheral blood and bone marrow eosinophilia, lung infiltrates, and Th2 cytokine levels in lung and serum. The results contrast with a recent report using one of the OVA-induced asthma models studied here. Similar immune responses were also observed in CCR8(-/-) and wild-type animals in a different model of ragweed allergen-induced peritoneal eosinophilic inflammation, with an equivalent number of eosinophils and analogous increased levels of Th2 cytokines in peritoneum and peripheral blood. Our results show that allergic diseases course without critical CCR8 participation, and suggest that further work is needed to unravel the in vivo role of CCR8 in Th2-mediated pathologies.

Murine cytomegalovirus infection alters Th1/Th2 cytokine expression, decreases airway eosinophilia, and enhances mucus production in allergic airway disease.

Concomitant infection of murine CMV (MCMV), an opportunistic respiratory pathogen, altered Th1/Th2 cytokine expression, decreased bronchoalveolar lavage (BAL) fluid eosinophilia, and increased mucus production in a murine model of OVA-induced allergic airway disease. Although no change in the total number of leukocytes infiltrating the lung was observed between challenged and MCMV/challenged mice, the cellular profile differed dramatically. After 10 days of OVA-aerosol challenge, eosinophils comprised 64% of the total leukocyte population in BAL fluid from challenged mice compared with 11% in MCMV/challenged mice. Lymphocytes increased from 11% in challenged mice to 30% in MCMV/challenged mice, and this increase corresponded with an increase in the ratio of CD8(+) to CD4(+)TCRalphabeta lymphocytes. The decline in BAL fluid eosinophilia was associated with a change in local Th1/Th2 cytokine profiles. Enhanced levels of IL-4, IL-5, IL-10, and IL-13 were detected in lung tissue from challenged mice by RNase protection assays. In contrast, MCMV/challenged mice transiently expressed elevated levels of IFN-gamma and IL-10 mRNAs, as well as decreased levels of IL-4, IL-5, and IL-13 mRNAs. Elevated levels of IFN-gamma and reduced levels of IL-5 were also demonstrated in BAL fluid from MCMV/challenged mice. Histological evaluation of lung sections revealed extensive mucus plugging and epithelial cell hypertrophy/hyperplasia only in MCMV/challenged mice. Interestingly, the development of airway hyperresponsiveness was observed in challenged mice, not MCMV/challenged mice. Thus, MCMV infection can modulate allergic airway inflammation, and these findings suggest that enhanced mucus production may occur independently of BAL fluid eosinophilia.