Tomohisa Iinuma

The Interleukin-33-p38 Kinase Axis Confers Memory T Helper 2 Cell Pathogenicity in the Airway

Memory CD4(+) T helper (Th) cells provide long-term protection against pathogens and are essential for the development of vaccines; however, some antigen-specific memory Th cells also drive immune-related pathology, including asthma. The mechanisms regulating the pathogenicity of memory Th cells remain poorly understood. We found that interleukin-33 (IL-33)-ST2 signals selectively licensed memory Th2 cells to induce allergic airway inflammation via production of IL-5 and that the p38 MAP kinase pathway was a central downstream target of IL-33-ST2 in memory Th2 cells. In addition, we found that IL-33 induced upregulation of IL-5 by memory CD4(+) T cells isolated from nasal polyps of patients with eosinophilic chronic rhinosinusitis. Thus, IL-33-ST2-p38 signaling appears to directly instruct pathogenic memory Th2 cells to produce IL-5 and induce eosinophilic inflammation.

Thy1+IL-7+ lymphatic endothelial cells in iBALT provide a survival niche for memory T-helper cells in allergic airway inflammation

Significance A substantial proportion of people have intractable chronic allergic diseases for which no curative treatment exists. A clear understanding of how these allergic diseases develop and persist is lacking. Here, unique ectopic lymphoid-like structures called inducible bronchus-associated lymphoid tissue were found to be formed during chronic airway inflammation, and were critical in persistent inflammation. In addition, we identified a Thy1+IL-7+IL-33+ subset of lymphatic endothelial cells (LECs) that support the maintenance of memory-type pathogenic T helper 2 (Tpath2) cells. A similar population of IL-7+IL-33+ LECs was found in nasal polyps of patients with eosinophilic chronic rhinosinusitis. Thus, we revealed that Thy1+IL-7–producing LECs control chronic allergic airway inflammation by supporting memory-type Tpath2 cells in human and mouse systems. Memory CD4+ T helper (Th) cells are central to long-term protection against pathogens, but they can also be pathogenic and drive chronic inflammatory disorders. How these pathogenic memory Th cells are maintained, particularly at sites of local inflammation, remains unclear. We found that ectopic lymphoid-like structures called inducible bronchus-associated lymphoid tissue (iBALT) are formed during chronic allergic inflammation in the lung, and that memory-type pathogenic Th2 (Tpath2) cells capable of driving allergic inflammation are maintained within the iBALT structures. The maintenance of memory Th2 cells within iBALT is supported by Thy1+IL-7–producing lymphatic endothelial cells (LECs). The Thy1+IL-7–producing LECs express IL-33 and T-cell–attracting chemokines CCL21 and CCL19. Moreover, ectopic lymphoid structures consisting of memory CD4+ T cells and IL-7+IL-33+ LECs were found in nasal polyps of patients with eosinophilic chronic rhinosinusitis. Thus, Thy1+IL-7–producing LECs control chronic allergic airway inflammation by providing a survival niche for memory-type Tpath2 cells.

Interleukin-25 and mucosal T cells in noneosinophilic and eosinophilic chronic rhinosinusitis

BACKGROUND Chronic rhinosinusitis with nasal polyps (CRSwNP) is a heterogeneous disease of uncertain pathogenesis. Memory T cells acquire additional functions during the secondary response and play important roles in chronic inflammation. OBJECTIVE To investigate characteristics of tissue memory CD4(+) T cells obtained from patients with noneosinophilic CRSwNP (NECRS) and eosinophilic CRSwNP (ECRS) by focusing on the influence of interleukin (IL)-25. METHODS Pro-allergic cytokines in tissue homogenates were measured using enzyme-linked immunosorbent assays. NP mononuclear cells and CD4(+) T cells were isolated from NPs from patients with CRSwNP. Cytokine expression and CD4(+) T-cell subpopulations were analyzed using enzyme-linked immunosorbent assay, flow cytometry, and real-time polymerase chain reaction. RESULTS The IL-25 level in NPs increased in patients with ECRS. IL-5 and IL-9 mRNA levels expressed by tissue CD4(+) T cells were significantly elevated in patients with ECRS. Most infiltrating CD4(+) T cells in ECRS and NECRS expressed CD45RO; however, regardless of the atopic status, high IL-17RB levels were detected in CD4(+) T cells from patients with ECRS. IL-17RB mRNA levels expressed by tissue CD4(+) T cells significantly correlated with the number of eosinophils in NPs. Elevation of IL-5 and IL-9 production was found in NP mononuclear cells from patients with ECRS, but not in those from patients with NECRS, by stimulation with IL-25 under T-cell receptor stimulation. CONCLUSION Interleukin-25 and a subpopulation of tissue T-helper type 2 and 9 cells that express increased IL-17RB levels could contribute to infiltration of eosinophils in NPs and could have produced the pathologic difference between NECRS and ECRS.

Randomized double-blind study of prophylactic treatment with an antihistamine for seasonal allergic rhinitis.

Background: The efficacy of prophylactic treatment before the start of pollen dispersal for prevention of aggravation of symptoms is unclear. The aim of the present study was to examine the efficacy of prophylactic treatment with an antihistamine for seasonal allergic rhinitis (SAR) using an environmental challenge chamber (ECC). Methods: The study was performed in a randomized double-blind manner with a 3-way crossover design. The subjects were 50 patients with SAR caused by Japanese cedar pollen who were randomized for treatment with levocetirizine hydrochloride 5 mg (Xyzal®) or placebo as follows: administration of placebo for 8 days (treatment A), single administration of levocetirizine on day 8 after placebo for 7 days (treatment B) or administration of levocetirizine for 8 days (treatment C). Efficacy in each treatment arm was evaluated based on cedar pollen exposure for 3 h on day 9 in an ECC, following 1-hour exposure on day 8. The primary endpoint was the total nasal symptom score for 12 h on day 9. Other nasal and ocular symptoms were secondary endpoints. Results: The evaluation was performed in 45 subjects. The total nasal symptom score on day 9 was significantly lower with treatment B compared with treatment A. Treatment C did not show superior efficacy compared with treatment B. Conclusions: Our results suggest that early intervention with levocetirizine soon after onset of symptoms may attenuate these symptoms as effectively as prophylactic treatment before pollen dispersal. These results are important from the perspective of patient convenience and reduction of medical costs.

Myosin light chains 9 and 12 are functional ligands for CD69 that regulate airway inflammation

CD69 on activated T cells interacts with Myl9/12 expressed in inflamed airways, establishing tissue inflammation. Breathing down asthma’s neck Worldwide increases in the prevalence of chronic inflammatory diseases such as asthma highlight the need for new targeted therapies. CD4+ T cells that express the activation marker CD69 contribute to the pathogenesis of some types of asthma, but the exact role of CD69 remains unclear. Hayashizaki et al. reported that myosin light chain (Myl) 9 and Myl12 are functional ligands for CD69. Myl9/12 expression was increased in inflamed mouse airways and in patients with eosinophilic chronic rhinosinusitis. These data suggest that CD69-Myl9/12 interaction is involved in recruiting activated cells to inflamed tissues. Indeed, blocking CD69-Myl9/12 interaction in two different mouse models decreased allergic airway inflammation, suggesting that targeting CD69-Myl9/12 interaction could treat chronic inflammatory diseases. Recent decades have witnessed a rapid worldwide increase in chronic inflammatory disorders such as asthma. CD4+ T helper 2 cells play critical roles in the pathogenesis of allergic airway inflammation, and CD69 expression on activated CD4 T cells is required to induce allergic inflammation in tissues. However, how CD69 mechanistically controls allergic inflammation remains poorly defined. In lymphoid tissues, CD69 regulates cellular retention through inhibition of S1P1 expression and requires no specific ligands to function. In contrast, we show herein that myosin light chain (Myl) 9 and Myl12 are new functional ligands for CD69. Blockade of CD69-Myl9/12 interaction ameliorates allergic airway inflammation in ovalbumin-induced and house dust mite–induced mouse models of asthma. Within the inflamed mouse airways, we found that the expression of Myl9/12 was increased and that platelet-derived Myl9/12 localized to the luminal surface of blood vessels and formed intravascular net-like structures. Analysis of nasal polyps of eosinophilic chronic rhinosinusitis patients revealed that Myl9/12 expression was increased in inflammatory lesions and was distributed within net-like structures in the intravascular space. In addition, we detected Myl9/12 in perivascular spaces where many CD69+ cells were positioned within Myl9/12 structures. Thus, CD69-Myl9/12 interaction is a key event in the recruitment of activated CD69+ T cells to inflamed tissues and could be a therapeutic target for intractable airway inflammatory diseases.

Characteristics of the Chiba Environmental Challenge Chamber

BACKGROUND An environmental challenge chamber (ECC), which we refer to as the α-chamber, was built at Chiba University in 2008. The aim of this study was to validate the functionality of the ECC. METHODS The stability of the pollen distribution and concentration in the ECC and symptoms of patients with Japanese cedar pollinosis induced by cedar pollen exposure were examined. Carryover effects of symptoms induced by different exposure protocols and correlations between symptoms induced in the ECC and those in the natural cedar pollen season were also determined. All the studies using the α-chamber were conducted out of the cedar pollen season. RESULTS The severity of symptoms in the chamber reached a peak about 2 hours after the start of pollen exposure and plateaued thereafter. After subjects left the chamber, the symptoms persisted for several days. There was no significant difference between the severity of symptoms at exposure levels of 8000 and 12000 grains/m3. The symptoms were significantly increased by exposure for 3 consecutive days; however, there were no carryover effects in a study performed with a two-week interval. The total nasal symptom score (TNSS) in the natural pollen season showed a weak correlation with the mean TNSS on the day of exposure and the following 3 days. Symptoms in the ECC also had weak correlations with those in the early natural pollen season. CONCLUSIONS The ECC under well-controlled conditions is suitable for clinical studies and might accelerate development of treatment for seasonal allergic rhinitis. A complete evaluation requires inclusion of the persistent reaction after subjects leave the ECC.

Sublingual immunotherapy for allergic rhinitis: subjective versus objective tools to evaluate its success.

BACKGROUND Biomarkers that enable objective evaluation of the clinical effects of immunotherapy for allergic rhinitis have yet to be identified. METHODS This study included 40 patients who were enrolled in a large randomized, double-blind, placebo-controlled, multicenter study examining the efficacy of sublingual immunotherapy (SLIT) using Japanese cedar (JC) pollen extract during two consecutive pollen seasons from 2010 to 2012. Based on changes in total nasal symptom medication score, patients in the SLIT and placebo groups were subdivided into two subgroups: good responders and poor responders. The levels of JC pollen-specific IL-10+Foxp3+ cells and specific Th2 cytokine-producing cells were measured and the association with the efficacy of SLIT was analysed. RESULTS The total nasal symptom medication score was significantly lower in the SLIT group compared with the placebo group. The number of JC pollen-specific Th2 cytokine-producing cells increased during the pollen season in the placebo group and in poor responders in the SLIT group; however, the increases were inhibited in the good responders in the SLIT group. The number of JC pollen-specific IL-10+Foxp3+ cells increased only in these good responders. CONCLUSIONS Changes in levels of allergen-specific Th2 cytokine-producing cells and IL-10+Foxp3+ cells could be objective biomarkers for SLIT.

Identification of specifically reduced Th2 cell subsets in allergic rhinitis patients after sublingual immunotherapy

Although Th2 cells are well known to play important roles in allergic diseases including allergic rhinitis (AR), the factors that induce and sustain the pathogenesis of AR remain unclear. The recent development of sublingual immunotherapy (SLIT) is expected to allow changes to the underlying pathogenesis of AR. However, which Th2 cell subsets are important in house dust mite‐induced AR (HDM‐AR), the influence of SLIT on the pathogenic Th2 cells, and the association of Th2 cell subsets with SLIT efficacy have not been clarified.

Persistent nasal symptoms and mediator release after continuous pollen exposure in an environmental challenge chamber

BACKGROUND Immediate- and late-phase reactions are associated with nasal symptoms of patients with allergic rhinitis. OBJECTIVE To examine the symptoms and mediators released after continuous allergen exposure in an environmental challenge chamber (ECC). METHODS Fifteen patients with Japanese cedar pollinosis were enrolled in this study and continuously exposed to cedar pollen at a concentration of 8,000 grains/m(3) for 3 hours in an ECC. Nasal function tests were performed, and nasal secretions were collected before pollen exposure (0 hour), immediately after exiting the ECC (3 hours), and 6 hours after exiting the ECC (9 hours). Symptom scores were recorded every 30 minutes in the ECC and every 3 hours after exiting the ECC. The frequency of sneezing and nose blowing also was monitored. RESULTS The severity of symptoms in the ECC peaked approximately 2 hours after the beginning of pollen exposure and continued more than 6 hours after leaving the ECC. Concentrations of histamine, tryptase, interleukins 5, 3, 33, and 31, and substance P increased over time, whereas that of nasal fractional exhaled nitric oxide decreased. CONCLUSION Various mediators are released during continuous allergen exposure, which subsequently induce persistent nasal symptoms. Effective treatment is required to control the intense inflammation observed after allergen exposure.

Activation of invariant natural killer T cells in regional lymph nodes as new antigen-specific immunotherapy via induction of interleukin-21 and interferon-γ

Invariant natural killer T (iNKT) cells play important immunoregulatory functions in allergen‐induced airway hyperresponsiveness and inflammation. To clarify the role of iNKT cells in allergic rhinitis (AR), we generated bone marrow‐derived dendritic cells (BMDCs), which were pulsed by ovalbumin (OVA) and α‐galactosylceramide (OVA/α‐GalCer‐BMDCs) and administered into the oral submucosa of OVA‐sensitized mice before nasal challenge. Nasal symptoms, level of OVA‐specific immunoglobulin (IgE), and T helper type 2 (Th2) cytokine production in cervical lymph nodes (CLNs) were significantly ameliorated in wild‐type (WT) mice treated with OVA/α‐GalCer‐BMDCs, but not in WT mice treated with OVA‐BMDCs. These anti‐allergic effects were not observed in Jα18–/– recipients that lack iNKT cells, even after similar treatment with OVA/α‐GalCer‐BMDCs in an adoptive transfer study with CD4+ T cells and B cells from OVA‐sensitized WT mice. In WT recipients of OVA/α‐GalCer‐BMDCs, the number of interleukin (IL)‐21‐producing iNKT cells increased significantly and the Th1/Th2 balance shifted towards the Th1 dominant state. Treatment with anti‐IL‐21 and anti‐interferon (IFN)‐γ antibodies abrogated these anti‐allergic effects in mice treated with α‐GalCer/OVA‐BMDCs. These results suggest that activation of iNKT cells in regional lymph nodes induces anti‐allergic effects through production of IL‐21 or IFN‐γ, and that these effects are enhanced by simultaneous stimulation with antigen. Thus, iNKT cells might be a useful target in development of new treatment strategies for AR.