Toshiyuki Koya

Naturally Occurring Lung CD4+CD25+ T Cell Regulation of Airway Allergic Responses Depends on IL-10 Induction of TGF-β

Peripheral tolerance to allergens is mediated in large part by the naturally occurring lung CD4+CD25+ T cells, but their effects on allergen-induced airway responsiveness have not been well defined. Intratracheal, but not i.v., administration of naive lung CD4+CD25+ T cells before allergen challenge of sensitized mice, similar to the administration of the combination of rIL-10 and rTGF-β, resulted in reduced airway hyperresponsiveness (AHR) and inflammation, lower levels of Th2 cytokines, higher levels of IL-10 and TGF-β, and less severe lung histopathology. Significantly, CD4+CD25+ T cells isolated from IL-10−/− mice had no effect on AHR and inflammation, but when incubated with rIL-10 before transfer, suppressed AHR, and inflammation, and was associated with elevated levels of bronchoalveolar lavage TGF-β levels. By analogy, anti-TGF-β treatment reduced regulatory T cell activity. These data identify naturally occurring lung CD4+CD25+ T cells as capable of regulating lung allergic responses in an IL-10- and TGF-β-dependent manner.

Leukotriene B4 Receptor-1 Is Essential for Allergen-Mediated Recruitment of CD8 + T Cells and Airway Hyperresponsiveness

Recent studies in both human and rodents have indicated that in addition to CD4+ T cells, CD8+ T cells play an important role in allergic inflammation. We previously demonstrated that allergen-sensitized and -challenged CD8-deficient (CD8−/−) mice develop significantly lower airway hyperresponsiveness (AHR), eosinophilic inflammation, and IL-13 levels in bronchoalveolar lavage fluid compared with wild-type mice, and that all these responses were restored by adoptive transfer of in vivo-primed CD8+ T cells or in vitro-generated effector CD8+ T cells (TEFF). Recently, leukotriene B4 and its high affinity receptor, BLT1, have been shown to mediate in vitro-generated TEFF recruitment into inflamed tissues. In this study we investigated whether BLT1 is essential for the development of CD8+ T cell-mediated allergic AHR and inflammation. Adoptive transfer of in vivo-primed BLT1+/+, but not BLT1−/−, CD8+ T cells into sensitized and challenged CD8−/− mice restored AHR, eosinophilic inflammation, and IL-13 levels. Moreover, when adoptively transferred into sensitized CD8−/− mice, in vitro-generated BLT1+/+, but not BLT1−/−, TEFF accumulated in the lung and mediated these altered airway responses to allergen challenge. These data are the first to show both a functional and an essential role for BLT1 in allergen-mediated CD8+ TEFF recruitment into the lung and development of AHR and airway inflammation.

Anti-interferon-γ autoantibody in a patient with disseminated Mycobacterium avium complex

We report the case of a 44-year-old woman with disseminated Mycobacterium avium complex (MAC) infection involving multiple bone lesions despite a normal healthy status until 6 months previously. Because she was suspected to have acquired immunodeficiency, we tested interferon (IFN)-γ production by peripheral blood mononuclear cells (PBMC) after phytohemagglutinin (PHA) or anti-CD3 stimulation, and found that these cells produced no, or undetectable, levels of IFN-γ in the presence of the patient’s plasma, but produced nearly normal levels of IFN-γ in the presence of healthy donor plasma. Since the IgG fraction of the patient’s plasma was capable of blocking in vitro responses to IFN-γ, the cause of disseminated MAC infection in this case appeared to be anti-IFN-γ autoantibodies. To reduce the titer of anti-IFN-γ autoantibodies, the patient received intravenous immunoglobulin (IVIG). However, titer of autoantibodies changed little compared to that before IVIG administration. According to our literature search, this is only the second case of disseminated MAC infection associated with anti-IFN-γ autoantibodies in Japan.

Leukotriene B4 Receptor 1 Expression on Dendritic Cells Is Required for the Development of Th2 Responses and Allergen-Induced Airway Hyperresponsiveness

Dendritic cells (DC) are important APCs that control allergen-induced airway responses by interacting directly with T cells. Leukotriene B4 (LTB4), interacting with its high-affinity receptor, LTB4 receptor 1 (BLT1), is known to attract and activate leukocytes during inflammation. We have previously shown that BLT1 expression on Ag-primed T cells is required for the development of airway hyperresponsiveness (AHR; Miyahara et al. 2005. Am. J. Respir. Crit. Care Med. 172: 161–167). However, the role for the LTB4-BLT1 pathway in DC function in allergen-induced airway responses has not been defined. Bone marrow-derived DCs (BMDC) were generated. Naive BALB/c mice received OVA-pulsed BLT1-deficient (BLT1−/−) BMDCs or wild-type BMDCs intratracheally and were then challenged with OVA for 3 days. Airway responses were monitored 48 h after the last allergen challenge. BLT1−/− BMDCs showed normal maturation judged from surface expression of CD markers. Compared with recipients of wild-type BMDCs, mice that received BLT1−/− BMDCs developed significantly lower AHR to inhaled methacholine, lower goblet cell metaplasia, and eosinophilic infiltration in the airways and decreased levels of Th2 type cytokines in the bronchoalveolar lavage fluid. Migration of BLT1−/− BMDCs into peribronchial lymph nodes was significantly impaired compared with BLT1+/+ BMDCs after intratracheal instillation. These data suggest that BLT1 expression on DCs is required for migration of DCs to regional lymph nodes as well as in the development of AHR and airway inflammation.

CD8+ T Cell-Mediated Airway Hyperresponsiveness and Inflammation Is Dependent on CD4+IL-4+ T Cells

CD4+ T cells, particularly Th2 cells, play a pivotal role in allergic airway inflammation. However, the requirements for interactions between CD4+ and CD8+ T cells in airway allergic inflammation have not been delineated. Sensitized and challenged OT-1 mice in which CD8+ T cells expressing the transgene for the OVA257–264 peptide (SIINFEKL) failed to develop airway hyperresponsiveness (AHR), airway eosinophilia, Th2 cytokine elevation, or goblet cell metaplasia. OT-1 mice that received naive CD4+IL-4+ T cells but not CD4+IL-4− T cells before sensitization developed all of these responses to the same degree as wild-type mice. Moreover, recipients of CD4+IL-4+ T cells developed significant increases in the number of CD8+IL-13+ T cells in the lung, whereas sensitized OT-1 mice that received primed CD4+ T cells just before challenge failed to develop these responses. Sensitized CD8-deficient mice that received CD8+ T cells from OT-1 mice that received naive CD4+ T cells before sensitization increased AHR and eosinophil numbers in bronchoalveolar lavage fluid when challenged with allergen. In contrast, sensitized CD8-deficient mice receiving CD8+ T cells from OT-1 mice without CD4+ T cells developed reduced AHR and eosinophil numbers in bronchoalveolar lavage fluid when challenged. These data suggest that interactions between CD4+ and CD8+ T cells, in part through IL-4 during the sensitization phase, are essential to the development of CD8+IL-13+ T cell-dependent AHR and airway allergic inflammation.

Contribution of aspirin-intolerant asthma to near fatal asthma based on a questionnaire survey in Niigata Prefecture, Japan

Objective:  Prevention of deaths due to asthma is one of the most important issues in asthma management. However, there are few epidemiological studies of asthma deaths in Japan.

Critical Role of the Fc Receptor γ-Chain on APCs in the Development of Allergen-Induced Airway Hyperresponsiveness and Inflammation

The FcR common γ-chain (FcRγ) is an essential component of the receptors FcεRI, FcγRI, and FcγRIII, which are expressed on many inflammatory cell types. The role of these receptors in the initiation or maintenance of allergic inflammation has not been well defined. FcRγ-deficient (FcRγ−/−) and control (wild-type (WT)) mice were sensitized and subsequently challenged with OVA. Following sensitization and challenge to OVA, FcRγ-deficient (FcRγ−/−) mice developed comparable levels of IgE and IgG1 as WT mice. However, numbers of eosinophils, levels of IL-5, IL-13, and eotaxin in bronchoalveolar lavage fluid, and mononuclear cell (MNC) proliferative responses to OVA were significantly reduced, as was airway hyperresponsiveness (AHR) to inhaled methacholine. Reconstitution of FcRγ−/− mice with whole spleen MNC from WT mice before sensitization restored development of AHR and the numbers of eosinophils in bronchoalveolar lavage fluid; reconstitution after sensitization but before OVA challenge only partially restored these responses. These responses were also restored when FcRγ−/− mice received T cell-depleted MNC, T and B cell-depleted MNC, or bone marrow-derived dendritic cells before sensitization from FcR+/+ or FcγRIII-deficient but not FcRγ−/− mice. The expression levels of FcγRIV on bone marrow-derived dendritic cells from FcR+/+ mice were found to be low. These results demonstrate that expression of FcRγ, most likely FcγRI, on APCs is important during the sensitization phase for the development of allergic airway inflammation and AHR.

A Novel Prostacyclin Agonist Protects against Airway Hyperresponsiveness and Remodeling in Mice

Airway remodeling in bronchial asthma results from chronic, persistent airway inflammation. The effects of the reversal of airway remodeling by drug interventions remain to be elucidated. We investigated the effects of ONO-1301, a novel prostacyclin agonist with thromboxane inhibitory activity, on the prevention and reversibility of airway remodeling in an experimental chronic asthma model. Mice sensitized and challenged to ovalbumin (OVA) three times a week for 5 consecutive weeks were administered ONO-1301 or vehicle twice a day from the fourth week of OVA challenges. Twenty-four hours after the final OVA challenge, airway hyperresponsiveness (AHR) was assessed, and bronchoalveolar lavage was performed. Lung specimens were excised for staining to detect goblet-cell metaplasia, airway smooth muscle, and submucosal fibrosis. Mice administered ONO-1301 showed limited increases in AHR compared with mice administered the vehicle. The histological findings of airway remodeling were improved in ONO-1301-treated mice compared with vehicle-treated mice. Presumably, these therapeutic effects of ONO-1301 are attributable to the up-regulation of production of hepatocyte growth factor (HGF) in lung tissue, because the neutralization of HGF by antibodies prevented the effects of ONO-1301 on AHR and airway remodeling. Mice administered ONO-1301 showed similar levels of AHR and airway remodeling as mice administered montelukast, a cysteinyl-leukotriene-1 receptor antagonist, and lower levels were observed in mice administered dexamethasone. These data suggest that ONO-1301 exerts the effect of reversing airway remodeling, at least in part through an elevation of HGF in the lungs, and may be effective as an anti-remodeling drug in the treatment of asthma.

Plasticity of Invariant NKT Cell Regulation of Allergic Airway Disease Is Dependent on IFN-γ Production

Invariant NKT cells (iNKT cells) play a pivotal role in the development of allergen-induced airway hyperresponsiveness (AHR) and inflammation. However, it is unclear what role they play in the initiation (sensitization) phase as opposed to the effector (challenge) phase. The role of iNKT cells during sensitization was examined by determining the response of mice to intratracheal transfer of OVA-pulsed or OVA–α-galactosylceramide (OVA/αGalCer)-pulsed bone marrow-derived dendritic cells (BMDCs) prior to allergen challenge. Wild-type (WT) recipients of OVA-BMDCs developed AHR, increased airway eosinophilia, and increased levels of Th2 cytokines in bronchoalveolar lavage fluid, whereas recipients of OVA/αGalCer BMDCs failed to do so. In contrast, transfer of these same OVA/αGalCer BMDCs into IFN-γ–deficient (IFN-γ−/−) mice enhanced the development of these lung allergic responses, which was reversed by exogenous IFN-γ treatment following OVA-BMDC transfer. Further, Jα18-deficient recipients, which lack iNKT cells, developed the full spectrum of lung allergic responses following reconstitution with highly purified WT liver or spleen iNKT cells and transfer of OVA-BMDCs, whereas reconstituted recipients of OVA/αGalCer BMDCs failed to do so. Transfer of iNKT cells from IFN-γ−/− mice restored the development of these responses in Jα18-deficient recipients following OVA-BMDC transfer; the responses were enhanced following OVA/αGalCer BMDC transfer. iNKT cells from these IFN-γ−/− mice produced higher levels of IL-13 in vitro compared with WT iNKT cells. These data identify IFN-γ as playing a critical role in dictating the consequences of iNKT cell activation in the initiation phase of the development of AHR and airway inflammation.

Activation of naturally occurring lung CD4(+)CD25(+) regulatory T cells requires CD8 and MHC I interaction.

Naturally occurring Foxp3+CD4+CD25+ T cells (nTregs) isolated from lungs of naive mice regulate allergic airway hyperresponsiveness (AHR) and inflammation. Here, we demonstrate the critical requirement for engagement of MHC class I on CD4+CD25+ T cells by CD8 for the functional activation of these nTregs. Suppression of allergen-induced AHR and inflammation by nTregs was abolished in mice treated with anti-CD8. Correspondingly, decreased levels of IL-10 and TGF-β and increased levels of Th2 cytokines in bronchoalveolar lavage were detected in these treated mice. Similarly, nTregs isolated from β2m−/− mice or from mice treated with anti-MHC I antibody in vitro before intratracheal transfer failed to modulate AHR or inflammation. Coculture of nTregs with CD8+ T cells increased IL-10 and TGF-β. Addition of anti-MHC I or anti-CD8 reduced IL-10 and TGF-β. These results demonstrate that functional activation of nTregs requires the interaction between MHC I on CD4+CD25+ T cells and CD8.