Pronecroptotic Therapy Using Ceramide Nanoliposomes Is Effective for Triple-Negative Breast Cancer Cells

Regulated necrosis, termed necroptosis, represents a potential therapeutic target for refractory cancer. Ceramide nanoliposomes (CNLs), considered potential chemotherapeutic agents, induce necroptosis by targeting the activating protein mixed lineage kinase domain-like protein (MLKL). In the present study, we examined the potential of pronecroptotic therapy using CNLs for refractory triple-negative breast cancer (TNBC), for which there is a lack of definite and effective therapeutic targets among the various immunohistological subtypes of breast cancer. MLKL mRNA expression in tumor tissues was significantly higher in TNBC patients than in those with non-TNBC subtypes. Similarly, among the 50 breast cancer cell lines examined, MLKL expression was higher in TNBC-classified cell lines. TNBC cell lines were more susceptible to the therapeutic effects of CNLs than the non-TNBC subtypes of breast cancer cell lines. In TNBC-classified MDA-MB-231 cells, the knockdown of MLKL suppressed cell death induced by CNLs or the active substance short-chain C6-ceramide. Accordingly, TNBC cells were prone to CNL-evoked necroptotic cell death. These results will contribute to the development of CNL-based pronecroptotic therapy for TNBC.

Steroid-Insensitive Gene Expression of Extracellular Matrix Components and Pro-fibrotic Factors in the Lung Associated with Airway Hyperresponsiveness in Murine Asthma

Between 5 and 10% of asthma patients do not respond to glucocorticoid therapy. Experimental animal models are indispensable for investigating the pathogenesis of steroid-resistant asthma; however, the majority of murine asthma models respond well to glucocorticoids. We previously reported that multiple intratracheal administration of ovalbumin (OVA) at a high dose (500 µg/animal) induced steroid-insensitive airway eosinophilia and remodeling with lung fibrosis, whereas a low dose (5 µg/animal) caused steroid-sensitive responses. The aims of the present study were as follows: 1) to clarify whether airway hyperresponsiveness (AHR) in the two models is also insensitive and sensitive to a glucocorticoid, respectively, and 2) to identify steroid-insensitive genes encoding extracellular matrix (ECM) components and pro-fibrotic factors in the lung. In comparisons with non-challenged group, the 5- and 500-µg OVA groups both exhibited AHR to methacholine. Daily intraperitoneal treatment with dexamethasone (1 mg/kg) significantly suppressed the development of AHR in the 5-µg OVA group, but not in the 500-µg OVA group. Among genes encoding ECM components and pro-fibrotic factors, increased gene expressions of fibronectin and collagen types I, III, and IV as ECM components as well as 7 matrix metalloproteinases, tissue inhibitor of metalloproteinase-1, transforming growth factor-β1, and activin A/B as pro-fibrotic factors were insensitive to dexamethasone in the 500-µg OVA group, but were sensitive in the 5-µg OVA group. In conclusion, steroid-insensitive AHR developed in the 500-µg OVA group and steroid-insensitive genes encoding ECM components and pro-fibrotic factors were identified. Drugs targeting these molecules have potential in the treatment of steroid-resistant asthma.

Roles of type 1 regulatory T (Tr1) cells in allergen-specific immunotherapy

Allergen-specific immunotherapy (AIT) is the only causative treatment for allergic diseases by modification of the immune response to allergens. A key feature of AIT is to induce immunotolerance to allergens by generating antigen-specific regulatory T (Treg) cells in allergic patients. Type 1 regulatory T (Tr1) cells and forkhead box protein 3 (Foxp3)-expressing Treg cells are well known among Treg cell subsets. Foxp3 was identified as a master transcription factor of Treg cells, and its expression is necessary for their suppressive activity. In contrast to Foxp3⁺ Treg cells, the master transcription factor of Tr1 cells has not been elucidated. Nevertheless, Tr1 cells are generally considered as a distinct subset of Treg cells induced in the periphery during antigen exposure in tolerogenic conditions and can produce large amounts of anti-inflammatory cytokines such as interleukin-10 and transforming growth factor-β, followed by down-regulation of the function of effector immune cells independently of Foxp3 expression. Since the discovery of Tr1 cells more than 20 years ago, research on Tr1 cells has expanded our understanding of the mechanism of AIT. Although the direct precursors and true identity of these cells continues to be disputed, we and others have demonstrated that Tr1 cells are induced in the periphery by AIT, and the induced cells are re-activated by antigens, followed by suppression of allergic symptoms. In this review, we discuss the immune mechanisms for the induction of Tr1 cells by AIT and the immune-suppressive roles of Tr1 cells in AIT.

Local IL-10 replacement therapy was effective for steroid-insensitive asthma in mice

Subgroups of patients with severe asthma showing marked increases in sputum eosinophils and/or neutrophils are insensitive to corticosteroids. Previous reports have shown that exogenous administration of an anti-inflammatory cytokine, interleukin (IL)-10 negatively regulated both eosinophilic and neutrophilic migration into tissues. The objective of this study was to elucidate whether intratracheal IL-10 administration suppresses asthmatic responses in a steroid-insensitive model of mice. Ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at 500 µg/animal four times. Dexamethasone (1 mg/kg, intraperitoneal) or IL-10 (25 ng/mouse, intratracheal) was administered during the multiple challenges. The number of leukocytes, expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and IL-10 receptor in the lung, and the development of airway remodeling and hyperresponsiveness were evaluated after the fourth challenge. Consistent with our previous study, dexamethasone hardly suppressed the development of airway remodeling and hyperresponsiveness. Although intratracheal IL-10 administration did not affect the development of airway remodeling, the infiltration of eosinophils and neutrophils, and the development of airway hyperresponsiveness were significantly inhibited. Moreover, IL-10 administration significantly decreased the numbers of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, which express IL-10 receptor 1, even though neither production of eosinophilic nor neutrophilic cytokines in the lung was inhibited. Therefore, IL-10 can suppress eosinophil and neutrophil infiltration by inhibiting the proliferation of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, resulting in inhibition of airway hyperresponsiveness in steroid-insensitive asthmatic mice. IL-10 replacement therapy may be clinically useful for the treatment of steroid-insensitive asthma.

[Pathogenic changes in group 2 innate lymphoid cells (ILC2) in intractable asthma]

There is a certain population of intractable asthma patients, who can not be controlled by corticosteroid therapy. It has been suggested that 5-10% of asthma patients have been suffered from steroid resistance. Since it has been difficult to develop a steroid-resistant asthma model, the detailed mechanisms have been unclear. Recently, an intractable asthma model showing steroid insensitivity was developed by the author and colleagues. We found that pathogenic changes in type 2 innate lymphoid cells (ILC2) were induced in the intractable asthma. When ovalbumin (OVA) + Al(OH)₃-sensitized BALB/c mice were intratracheally challenged with OVA at 5 μg/animal, development of airway remodeling as well as lung eosinophilia and neutrophilia were markedly suppressed by treatment with dexamethasone. In contrast, when increasing the dose of OVA for challenges to 500 μg/animal, those asthmatic responses turned to be steroid insensitive. When Th2 cells and ILC2 in the lung were stimulated in vitro, ILC2 produced larger amounts of type 2 cytokines than Th2 cells. Interestingly, amounts of type 2 cytokines produced by the steroid-insensitive model-derived ILC2 were significantly larger than those by the steroid-sensitive, and that the former ILC2 exhibited higher expression of thymic stromal lymphopoietin (TSLP) receptor and signal transducer and activator of transcription (STAT) 5a gene. Treatment with anti-IL-5 antibody improved the steroid sensitivity. Taken together, ILC2 have been transformed to be pathogenic in the intractable asthma. IL-5 hyper-produced from ILC2 may be involved in the development of steroid resistance. The molecules related to the above mentioned are expected to be targets for development of new therapeutic drugs for intractable asthma.

Pathogenic changes in group 2 innate lymphoid cells (ILC2s) in a steroid-insensitive asthma model of mice

A certain population of asthma patients is resistant to steroid therapy, whereas the mechanisms remain unclear. One of characteristic features of steroid-resistant asthma patients is severe airway eosinophilia based on type-2 inflammation. Aims of this study were: 1) to develop a murine model of steroid-resistant asthma, 2) to elucidate that predominant cellular source of a type-2 cytokine, IL-5 was group 2 innate lymphoid cells (ILC2s), 3) to analyze pathogenic alteration of ILC2s in the severe asthma, and 4) to evaluate therapeutic potential of anti-IL-5 monoclonal antibody (mAb) on the steroid-resistant asthma. Ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at 5 or 500 μg/animal 4 times. Development of airway eosinophilia and remodeling in 5-μg OVA model were significantly suppressed by 1 mg/kg dexamethasone, whereas those in 500-μg OVA model were relatively insensitive to the dose of dexamethasone. ILC2s isolated from the lung of the steroid-insensitive model (500-μg OVA) produced significantly larger amounts of IL-5 in response to IL-33/TSLP than ILC2s from the steroid-sensitive model (5-μg OVA). Interestingly, TSLP receptor expression on ILC2s was up-regulated in the steroid-insensitive model. Treatment with anti-IL-5 mAb in combination with dexamethasone significantly suppressed the airway remodeling of the steroid-insensitive model. In conclusion, multiple intratracheal administration of a high dose of antigen induced steroid-insensitive asthma in sensitized mice. IL-5 was mainly produced from ILC2s, phenotype of which had been pathogenically altered probably through the up-regulation of TSLP receptors. IL-5 blockage could be a useful therapeutic strategy for steroid-resistant asthma.

[Anti-inflammatory Strategies by Focusing on the Particularity of Ocular Immunity]

Particularity of ocular immunity is manifested by "Immune privilege". For example, it has been generally known that corneal transplantation is a typically successful organ transplantation compared with other organs. This immune privilege can be explained by "immune-suppressive ocular microenvironment" and "anterior chamber-associated immune deviation, ACAID". This review focused on molecular mechanisms of the "immune-suppressive ocular microenvironment" and "ACAID", so that possible anti-inflammatory strategies could be raised. Especially, in murine ACAID model, anti-inflammatory actions were induced probably through induction of Treg cells. As an anti-inflammatory strategy, anti-inflammatory Treg cells could be induced in vitro. Treg cells that are specifically responsive for a specific antigen can be induced by culturing spleen cells with the antigen and transforming growth factor-β (TGF-β). The induced Treg cells were activated by stimulation with the specific antigen. When the induced Treg cells were adoptively transferred to recipient mice, antigen-induced inflammation was effectively suppressed. The Treg cells may be able to be efficiently induced by eye-based mechanisms. Further analyses of mechanisms underlying the ocular immune privilege can be useful for development of new anti-inflammatory strategies on the eye basis.

Importance of the Azole Moiety of Cimetidine Derivatives for the Inhibition of Human Multidrug and Toxin Extrusion Transporter 1 (hMATE1)

Herein, we describe the design and synthesis of cimetidine analogs, as well as their inhibitory activity toward the human multidrug and toxin extrusion transporter 1 (hMATE1), which is related to nephrotoxicity of drugs. Cimetidine is the histamine H₂-receptor antagonist, but also inhibits hMATE1, which is known to cause renal impairment. We designed and synthesized cimetidine analogs to evaluate hMATE1 inhibitory activity to reveal whether the analogs could reduce the inhibition of hMATE1. The results showed that all analogs with an unsubstituted guanidino group exhibited hMATE1 inhibitory activity. On the other hand, there was a clear difference in the hMATE1 inhibitory activity for the other compounds. That is, compounds with a methylimidazole ring exhibited hMATE1 inhibition, while compounds with a phenyl ring did not. The results suggest that the ability to form hydrogen bonds at the azole moiety is strongly involved in the hMATE1 inhibition.

NOX1/NADPH oxidase is involved in the LPS-induced exacerbation of collagen-induced arthritis

We investigate as yet an unidentified role of NOX1, a non-phagocytic isoform of the superoxide-generating NADPH oxidase, in immune responses using Nox1-knockout mice (Nox1-KO). The transcripts of NOX1 was expressed in lymphoid tissues, including the spleen, thymus, bone marrow, and inguinal lymphoid nodes. When antibody production after ovalbumin (OVA) immunization was examined, no significant differences were observed in serum anti-OVA IgG levels between wild-type mice (WT) and Nox1-KO. In the experimental asthma, the infiltration of eosinophils and the Th2 cytokine response after the induction of asthma with OVA were similar between the two genotypes. However, the severity and incidence of experimental collagen-induced arthritis (CIA) following the administration of a low dose of endotoxin (LPS) were significantly lower in Nox1-KO. While neither serum levels of autoantibodies nor in vitro cytokine responses were affected by Nox1 deficiency, NOX1 mRNA levels in the spleen significantly increased after the LPS challenge. Among the spleen cells, remarkable LPS-induced upregulation of NOX1 was demonstrated in both CD11b+ monocytes/macrophages and CD11c+ dendritic cells, suggesting that LPS-inducible NOX1 in monocytes/macrophages/dendritic cells may modulate the development of experimental CIA. Therapeutic targeting of NOX1 may therefore control the onset and/or severity of arthritis which is exacerbated by bacterial infection.

Ceramide synthase 2-C24:1 -ceramide axis limits the metastatic potential of ovarian cancer cells

Regulation of sphingolipid metabolism plays a role in cellular homeostasis, and dysregulation of these pathways is involved in cancer progression. Previously, our reports identified ceramide as an anti-metastatic lipid. In the present study, we investigated the biochemical alterations in ceramide-centered metabolism of sphingolipids that were associated with metastatic potential. We established metastasis-prone sublines of SKOV3 ovarian cancer cells using an in vivo selection method. These cells showed decreases in ceramide levels and ceramide synthase (CerS) 2 expression. Moreover, CerS2 downregulation in ovarian cancer cells promoted metastasis in vivo and potentiated cell motility and invasiveness. Moreover, CerS2 knock-in suppressed the formation of lamellipodia required for cell motility in this cell line. In order to define specific roles of ceramide species in cell motility controlled by CerS2, the effect of exogenous long- and very long-chain ceramide species on the formation of lamellipodia was evaluated. Treatment with distinct ceramides increased cellular ceramides and had inhibitory effects on the formation of lamellipodia. Interestingly, blocking the recycling pathway of ceramides by a CerS inhibitor was ineffective in the suppression of exogenous C24:1 -ceramide for the formation of lamellipodia. These results suggested that C24:1 -ceramide, a CerS2 metabolite, predominantly suppresses the formation of lamellipodia without the requirement for deacylation/reacylation. Moreover, knockdown of neutral ceramidase suppressed the formation of lamellipodia concomitant with upregulation of C24:1 -ceramide. Collectively, the CerS2-C24:1 -ceramide axis, which may be countered by neutral ceramidase, is suggested to limit cell motility and metastatic potential. These findings may provide insights that lead to further development of ceramide-based therapy and biomarkers for metastatic ovarian cancer.

Diet-Induced Mouse Model of Atopic Dermatitis

Atopic dermatitis (AD) is a common skin disease characterized by chronic inflammation and itchiness. Although skin barrier dysfunction and immune abnormalities are thought to contribute to the development of AD, the precise pathogenic mechanism remains to be elucidated. We have developed a unique, diet-induced AD mouse model based on the findings that deficiencies of certain polyunsaturated fatty acids and starches cause AD-like symptoms in hairless mice. Here, we present a protocol and tips for establishing an AD mouse model using a custom diet modified from a widely used standard diet (AIN-76A Rodent Diet). We also describe methods for evaluating skin barrier dysfunction and analyzing itch-related scratching behavior. This model can be used not only to investigate the complex pathogenic mechanism of human AD but also to study the puzzling relationship between nutrition and AD development.

Steroid-Resistant Asthma and Neutrophils

Asthma patients are classified by phenotype and endotype. Although symptoms in most asthma patients are well controlled by glucocorticoid treatment, certain populations of severe eosinophilic asthma patients in T-helper 2 (Th2)/type 2 asthma and neutrophilic asthma patients in non-Th2/type 2 asthma show insensitivity to inhaled or oral glucocorticoid therapy. In some cases of severe eosinophilic asthma, eosinophils remain in the lungs despite glucocorticoid therapy. It was reported that interleukin (IL)-33-induced activation of type 2 innate lymphoid cells (ILC2) was resistant to glucocorticoid treatment in certain allergic conditions. Regarding neutrophilic airway inflammation in steroid-resistant asthma, IL-17 derived from Th17 cells and IL-8 and tumor necrosis factor-α derived mainly from macrophages were reported to be involved in the pathogenesis. Recently, "NETosis," a specific cell death of neutrophils, has been reported to be involved in asthmatic airway inflammation. When NETosis is induced in asthma, aggravation of inflammation and delay of tissue repair could occur, suggesting that NETosis may be associated with the development of steroid-resistant asthma. This article reviews the pathogenesis of steroid-resistant asthma by focusing mainly on neutrophils.

Sustained effects of intralymphatic pollen-specific immunotherapy on Japanese cedar pollinosis

BACKGROUND

Intralymphatic immunotherapy (ILIT) for allergic patients requires only a few intralymphatic injections of the allergen. However, the effectiveness and safety for Japanese cedar pollinosis are unclear. The objectives of this study were to clarify whether and how long ILIT is effective for pollinosis, and its safety.

METHODS

In an open pilot investigation followed by a double-blind, placebo-controlled study, patients with Japanese cedar pollinosis received 3 intralymphatic inguinal injections of the pollen extracts before the first pollen season. The symptom medication score (SMS), nasal provocation testing and scoring visual analogue scale (VAS) were assessed after the first-third seasons.

RESULTS

(1) Although mild adverse events were induced at the injected site, severe adverse events were not noted. (2) During the latter part of the first season, ILIT-treated patients (n=12) tended to show improved SMS compared to placebo-treated (n=6) without statistical significance. When assessed by nasal provocation testing and VAS scoring after the first season, the effectiveness of ILIT was significant. (3) The effects of ILIT continued until the second or third season. (4) Neither allergen-specific antibodies nor Treg/Breg cells changed in the peripheral blood.

CONCLUSIONS

ILIT was safe and effective for Japanese cedar pollinosis. The clinical effects remained for 1-2 years.

Regulatory T and B cells in peripheral blood of subcutaneous immunotherapy-treated Japanese cedar pollinosis patients

AIM

The aim of this study was to clarify whether there are more regulatory T (Treg) and regulatory B (Breg) cells, and higher levels of IL-10-related transcription factors in subcutaneous immunotherapy (SCIT)-treated pollinosis patients than in non-SCIT-treated patients.

METHODS

Japanese cedar pollinosis patients undergoing SCIT had received treatment for at least 2.8 years. Peripheral blood mononuclear cells were used for flow cytometer analyses and mRNA measurement.

RESULTS

The numbers of type 1 regulatory T (Tr1)-like cells and Breg cells, and expression of E4BP4 mRNA by peripheral blood mononuclear cells in SCIT-treated patients were higher than those in non-SCIT-treated patients.

CONCLUSION

Tr1-like cells, Breg cells and E4BP4 may be involved in the effectiveness of SCIT.

Regulation of Necroptosis by Phospholipids and Sphingolipids

Several non-apoptotic regulated cell death pathways have been recently reported. Necroptosis, a form of necrotic-regulated cell death, is characterized by the involvement of receptor-interacting protein kinases and/or the pore-forming mixed lineage kinase domain-like protein. Recent evidence suggests a key role for lipidic molecules in the regulation of necroptosis. The purpose of this mini-review is to outline the regulation of necroptosis by sphingolipids and phospholipids.

CD8+ T cells regulated by CD4+CD25+ regulatory T cells in the early stage exacerbate the development of Dermatophagoides farinae-induced skin lesions via increasing mast cell infiltration in mice

Atopic dermatitis is a chronic inflammatory skin disease associated with CD4⁺ Th2 cell-shifted immune responses. Although the infiltration of skin lesions by CD8⁺ T cells has been recognized, their roles have not been fully defined. In this study, we examined the relationship between CD4⁺ and CD8⁺ cells in antigen-induced skin lesions of mice. BALB/c mice were repeatedly challenged with Dermatophagoides farinae (Der f) applied to the right ear nine times. Pre-treatment with anti-CD4 monoclonal antibody (mAb) during the third to sixth challenges, but not the post-treatment during the sixth to ninth challenges, exacerbated the development of Der f-induced ear swelling; pre-treatment with anti-CD25 mAb, which depletes regulatory T cells (Tregs), also exacerbated the lesions. Furthermore, the number of CD8⁺ T cells in lymph nodes was augmented by these pre-treatments. These findings prompted us to examine the effect of anti-CD8 mAb. Pre-treatment with anti-CD8 mAb, but not post-treatment, strongly inhibited the development of Der f-induced ear swelling; additionally, the epidermal hyperplasia and infiltration of mast cells were inhibited by the pre-treatment. Collectively, we revealed that CD8⁺ T cells regulated by CD4⁺CD25⁺ Tregs in the early stage are key contributors to the development of Der f-induced skin lesions via increasing mast cell infiltration, indicating that CD8⁺ T and Tregs could be potential therapeutic targets for atopic dermatitis.

[Analyses of Foxp3+ Treg cells and Tr1 cells in subcutaneous immunotherapy-treated allergic individuals in humans and mice]

Subcutaneous immunotherapy (SCIT) is a causative treatment for allergic diseases. More recently, it has become clear that regulatory T (Treg) cells are increased by SCIT. Treg cells are generally divided into two main groups: 1) CD25⁺ Foxp3⁺ CD4⁺ T cells (Foxp3⁺ Treg cells) and 2) IL-10-producing Foxp3^- CD4⁺ T cells (Tr1 cells). We demonstrated that the number of Tr1 cells in peripheral blood mononuclear cells in SCIT-treated pollinosis patients were significantly higher than that in non-SCIT-treated patients, but Foxp3⁺ Treg cells were not. Consistent with the results of human peripheral blood, Tr1 cells were increased in the lungs of asthmatic mice by SCIT, but Foxp3⁺ Treg cells were not. Moreover, in vitro-induced Tr1 cells were responded to the antigen to produce a large amount of IL-10 in in vitro and in vivo. Adoptive transfer of the induced Tr1 cells significantly suppressed the development of asthma. In any species of human and mouse, the increase in Tr1 cells rather than Foxp3⁺ Treg cells could be important for the effects of SCIT. The increased Tr1 cells by SCIT functionally suppressed allergic asthma probably via production of IL-10 in response to the specific antigen. Therefore, analyses of the induction mechanisms of Tr1 cells and search for compounds which induce Tr1 cells are thought to lead to development of more efficient SCIT.

Pharmacokinetic interference of doxorubicin with tolbutamide due to reduced metabolic clearance with increased serum unbound fraction in rats

The study examined the effect of doxorubicin (DOX) on the hepatic expression of CYP2C and its activity for metabolizing tolbutamide (TB), a specific CYP2C substrate, in rats and whether the pharmacokinetics of tolbutamide were altered by doxorubicin exposure. The expression level of hepatic CYP2C11 was depressed 1 day after doxorubicin administration (day 1), and this effect on CYP2C11 was augmented on day 4. However, the expression level of hepatic CYP2C6 remained unchanged. The activity of tolbutamide 4-hydroxylation in hepatic microsomes was decreased with time following doxorubicin administration. Regarding the enzyme kinetic parameters for tolbutamide 4-hydroxylation on day 4, the maximum velocity (V_max ) was significantly lower in the DOX group than that in the control group, while the Michaelis constant (K_m ) was unaffected. On pharmacokinetic examination, the total clearance (CL_tot ) of tolbutamide on day 4 was increased, despite the decreased metabolic capacity. On the other hand, the serum unbound fraction (f_u ) of tolbutamide was elevated with a reduced serum albumin concentration in the DOX group. Contrary to CL_tot , CL_tot /f_u , a parameter approximated to the hepatic intrinsic clearance of unbound tolbutamide, was estimated to be significantly reduced in the DOX group. These findings indicate that the metabolic capacity of CYP2C11 in the liver is depressed time-dependently by down-regulation after doxorubicin exposure in rats, and that the decreased enzyme activity of TB 4-hydroxylation in hepatic microsomes reflects the pharmacokinetic change of unbound tolbutamide, not total tolbutamide, in serum.

Perturbation of the immune cells and prenatal neurogenesis by the triplication of the Erg gene in mouse models of Down syndrome

Some mouse models of Down syndrome (DS), including Ts1Cje mice, exhibit impaired prenatal neurogenesis with yet unknown molecular mechanism. To gain insights into the impaired neurogenesis, a transcriptomic and flow cytometry analysis of E14.5 Ts1Cje embryo brain was performed. Our analysis revealed that the neutrophil and monocyte ratios in the CD45-positive hematopoietic cells were relatively increased, in agreement with the altered expression of inflammation/immune-related genes, in Ts1Cje embryonic brain, whereas the relative number of brain macrophages was decreased in comparison to wild-type mice. Similar upregulation of inflammation-associated mRNAs was observed in other DS mouse models, with variable trisomic region lengths. We used genetic manipulation to assess the contribution of Erg, a trisomic gene in these DS models, known to regulation hemato-immune cells. The perturbed proportions of immune cells in Ts1Cje mouse brain were restored in Ts1Cje-Erg^+/+/Mld2 mice, which are disomic for functional Erg but otherwise trisomic on a Ts1Cje background. Moreover, the embryonic neurogenesis defects observed in Ts1Cje cortex were reduced in Ts1Cje-Erg^+/+/Mld2 embryos. Our findings suggest that Erg gene triplication contributes to the dysregulation of the homeostatic proportion of the populations of immune cells in the embryonic brain and decreased prenatal cortical neurogenesis in the prenatal brain with DS.

Brain allopregnanolone induces marked scratching behaviour in diet-induced atopic dermatitis mouse model

Allopregnanolone (ALLO) is a neurosteroid produced in the brain, but so far, no study has explored its link with itching. Herein, we used a diet-induced atopic dermatitis mouse model to examine whether exogenously administered and endogenously produced ALLO contribute to inducing scratching. Systemic administration of ALLO elicited robust scratching in the atopic dermatitis model, while it did not affect spontaneous and pruritogen-induced scratching in normal mice. ALLO caused scratching when administered intracisternally, but not when administered intrathecally or intradermally, suggesting the involvement of supraspinal mechanisms. Pharmacological analyses suggested that both γ-aminobutyric acid type A receptor activation and serotonin type 3 receptor inhibition were involved in ALLO-induced scratching. We next examined whether endogenously produced ALLO is involved in ethanol-induced scratching in atopic dermatitis mice, because ethanol administration increases ALLO in rodent brain. Acute ethanol administration increased brain ALLO levels, which coincided with increased scratching. Pre-treatment with finasteride, a synthetic ALLO inhibitor, suppressed ethanol-induced scratching and ALLO production in the brain. Collectively, our results demonstrated for the first time that ALLO administration caused marked scratching in atopic dermatitis mice, and ethanol-induced scratching may be mediated through endogenously produced brain ALLO.

Antigen-specific airway IL-33 production depends on FcγR-mediated incorporation of the antigen by alveolar macrophages in sensitized mice

Although interleukin (IL)-33 is a candidate for the aggravation of asthma, the mechanisms underlying antigen-specific IL-33 production in the lung are unclear. Therefore, we analysed the mechanisms in mice. Intra-tracheal administration of ovalbumin (OVA) evoked increases in IL-33 and IL-33 mRNA in the lungs of both non-sensitized and OVA-sensitized mice, and the increases in the sensitized mice were significantly higher than in the non-sensitized mice. However, intra-tracheal administration of bovine serum albumin did not increase the IL-33 level in the OVA-sensitized mice. Depletion of neither mast cells/basophils nor CD4⁺ cells abolished the OVA-induced IL-33 production in sensitized mice, suggesting that the antigen recognition leading to the IL-33 production was not related with either antigen-specific IgE-bearing mast cells/basophils or memory CD4⁺ Th2 cells. When a fluorogenic substrate-labelled OVA (DQ-OVA) was intra-tracheally administered, the lung cells of sensitized mice incorporated more DQ-OVA than those of non-sensitized mice. The lung cells incorporating DQ-OVA included B-cells and alveolar macrophages. The allergic IL-33 production was significantly reduced by treatment with anti-FcγRII/III mAb. Depletion of alveolar macrophages by clodronate liposomes significantly suppressed the allergic IL-33 production, whereas depletion of B-cells by anti-CD20 mAb did not. These results suggest that the administered OVA in the lung bound antigen-specific IgG Ab, and then alveolar macrophages incorporated the immune complex through FcγRII/III on the cell surface, resulting in IL-33 production in sensitized mice. The mechanisms underlying the antigen-specific IL-33 production may aid in development of new pharmacotherapies.

Eicosapentaenoic acid ethyl ester ameliorates atopic dermatitis-like symptoms in special diet-fed hairless mice, partly by restoring covalently bound ceramides in the stratum corneum

Skin barrier dysfunction has a key role in the development of atopic dermatitis (AD). Covalently bound ceramides (Cer), which are essential lipids for permeability barrier homoeostasis, are reportedly decreased in the stratum corneum (SC) of AD patients. Hairless mice fed a special diet develop pruritic dermatitis resembling human AD. Our previous study found that oral administration of the n-3 polyunsaturated fatty acid α-linolenic acid ameliorated skin barrier dysfunction in AD mice with concomitant increase in serum eicosapentaenoic acid (EPA). In this study, we examined the effects of EPA ethyl ester (EPA-E) on diet-induced AD in hairless mice. Oral administration of EPA-E ameliorated skin barrier dysfunction and pruritus in AD mice. In the SC of AD mice, covalently bound Cer were markedly diminished. EPA-E administration restored the lack of bound Cer. Our findings imply the possible therapeutic clinical application of EPA-E in the treatment of human AD.

Increased expression of CysLT2 receptors in the lung of asthmatic mice and role in allergic responses

Compared with CysLT₁ receptors, the functional role of CysLT₂ receptors in asthma has not been clarified. The purpose of this study was to determine 1) whether CysLT₂ receptors are expressed in the lung of mice and if expression increases in asthmatic mice, and 2) whether CysLT₂ receptors are involved in allergic leukocyte infiltration into the lung and in the development of airway remodeling in asthmatic mice. BALB/c mice were sensitized with ovalbumin (OVA) + Al(OH)₃, and intratracheally challenged with OVA 4 times. Lung tissue was isolated before and after the 4th OVA challenge for detection of CysLT₂ receptors by immunohistochemistry and flow cytometry. The effect of a CysLT₂ receptor antagonist BayCysLT₂RA on multiple antigen challenge-induced leukocyte infiltration into the lung and the development of airway remodeling was evaluated. Even in non-challenged mice, CysLT₂ receptors were expressed in bronchial smooth muscle. After multiple challenges, expression was also observed in leukocytes infiltrating into alveolar spaces. CysLT₂R⁺ leukocytes included alveolar macrophages, conventional dendritic cells, and eosinophils. BayCysLT₂RA significantly inhibited multiple antigen challenge-induced increases in eosinophils and mononuclear cells in the lung. The development of airway remodeling was tended to be suppressed by CysLT₂ receptor antagonist. In conclusion, CysLT₂ receptors were constitutively expressed in the lung, and expression was strengthened in asthmatic mice. Activation of CysLT₂ receptors was functionally involved in allergic leukocyte infiltration into the lung. The CysLT₂ receptor can be a molecular target for the development of new pharmacotherapies for asthma.

Analysis of major paralogs encoding the Fra a 1 allergen based on their organ-specificity in Fragaria × ananassa

Fra a 1 protein in strawberry causes oral allergic syndrome. Over 39 Fra a 1 paralogs have been identified in strawberry genome. Fra a 1.01 is major accumulating protein in edible organs. Strawberry fruits contain allergenic proteins that cause oral allergic syndrome. The hypothesized major allergen is Fra a 1, an ortholog of the birch pollen allergen protein Bet v 1. We organized Fra a 1 genes and analyzed their localizations at the transcriptional and translational levels. In total, 15 new Fra a 1 proteins were identified from the genomic database, increasing the total number of Fra a 1 to 30 proteins encoded by 39 genes. Fra a 1.02 was mostly expressed in receptacles, and Fra a 1.01 in achenes, when analyzed by RNA sequencing. Immunoblotting showed that the Fra a 1.01 protein was broadly accumulated in strawberry organs, while the Fra a 1.02 protein was mostly expressed in receptacles. Recombinant Fra a 1.01 strongly reacted with human IgE. The mRNA and protein expression levels of Fra a 1 did not correlate, indicating the importance of protein levels when evaluating the abundance of allergens in strawberry. Based on the localizations, accumulation levels and reactivity to human IgE, we determined that Fra a 1.01 was the most important allergen, followed by Fra a 1.02, and then other Fra a 1 proteins. The information obtained here will be useful for selecting the target Fra a 1 paralogs when breeding hypoallergenic strawberry.

Regulation of allergic airway inflammation by adoptive transfer of CD4+ T cells preferentially producing IL-10

Anti-inflammatory pharmacotherapy for asthma has mainly depended on the inhalation of glucocorticoids, which non-specifically suppress immune responses. If the anti-inflammatory cytokine interleukin (IL)-10 can be induced by a specific antigen, asthmatic airway inflammation could be suppressed when individuals are exposed to the antigen. The purpose of this study was to develop cellular immunotherapeutics for atopic diseases using IL-10-producing CD4⁺ T cells. Spleen cells isolated from ovalbumin (OVA)-sensitized mice were cultured with the antigen, OVA and growth factors, IL-21, IL-27 and TGF-β for 7 days. After the 7-day culture, the CD4⁺ T cells were purified using a murine CD4 magnetic beads system. When the induced CD4⁺ T cells were stimulated by OVA in the presence of antigen-presenting cells, IL-10 was preferentially produced in vitro. When CD4⁺ T cells were adoptively transferred to OVA-sensitized mice followed by intratracheal OVA challenges, IL-10 was preferentially produced in the serum and bronchoalveolar lavage fluid in vivo. IL-10 production coincided with the inhibition of eosinophilic airway inflammation and epithelial mucus plugging. Most of the IL-10-producing CD4⁺ T cells were negative for Foxp3 and GATA-3, transcription factors of naturally occurring regulatory T cells and Th2 cells, respectively, but double positive for LAG-3 and CD49b, surface markers of inducible regulatory T cells, Tr1 cells. Collectively, most of the induced IL-10-producing CD4⁺ T cells could be Tr1 cells, which respond to the antigen to produce IL-10, and effectively suppressed allergic airway inflammation. The induced Tr1 cells may be useful for antigen-specific cellular immunotherapy for atopic diseases.

A new CysLT1 and CysLT2 receptors-mediated anaphylaxis guinea pig model

Although the effectiveness of CysLT₁ receptor antagonists on asthma has been clinically established, the effects of CysLT₂ receptor antagonists are still unclear. The purpose of this study was to develop a new CysLT₁ and CysLT₂ receptors-mediated anaphylaxis guinea pig model using S-hexyl GSH, a γ-glutamyl transpeptidase (GTP) inhibitor, to suppress conversion of LTC₄ to LTD₄. Actively sensitized guinea pigs were challenged with OVA in the absence or presence of S-hexyl GSH, and survival rate following anaphylactic response was monitored. OVA-induced fatal anaphylaxis in the absence of S-hexyl GSH was almost completely inhibited by montelukast, a CysLT₁ receptor antagonist, but not by the CysLT₂ receptor antagonist BayCysLT₂RA. However, under treatment with S-hexyl-GSH, the inhibitory effect of motelukast was dramatically diminished, whereas that of BayCysLT₂RA was markedly increased. The dual CysLT_1/2 receptor antagonist ONO-6950 effectively inhibited anaphylactic response in both S-hexyl GSH-treated and non-treated animals. LC/MS/MS analysis revealed that S-hexyl GSH treatment actually inhibited LTC₄ metabolism in the blood and lung tissues. Using S-hexyl GSH, we developed a novel CysLT₁ and CysLT₂ receptors-mediated anaphylaxis guinea pig model that can be useful for not only screening both CysLT₂ and CysLT_1/2 receptors antagonists, but also for functional analysis of CysLT₂ receptors.

CysLT2 receptor activation is involved in LTC4-induced lung air-trapping in guinea pigs

CysLT₁ receptors are known to be involved in the pathogenesis of asthma. However, the functional roles of CysLT₂ receptors in this condition have not been determined. The purpose of this study is to develop an experimental model of CysLT₂ receptor-mediated LTC₄-induced lung air-trapping in guinea pigs and use this model to clarify the mechanism underlying response to such trapping. Because LTC₄ is rapidly converted to LTD₄ by γ-glutamyltranspeptidase (γ-GTP) under physiological conditions, S-hexyl GSH was used as a γ-GTP inhibitor. In anesthetized artificially ventilated guinea pigs with no S-hexyl GSH treatment, i.v. LTC₄-induced bronchoconstriction was almost completely inhibited by montelukast, a CysLT₁ receptor antagonist, but not by BayCysLT₂RA, a CysLT₂ receptor antagonist. The inhibitory effect of montelukast was diminished by treatment with S-hexyl GSH, whereas the effect of BayCysLT₂RA was enhanced with increasing dose of S-hexyl GSH. Macroscopic and histological examination of lung tissue isolated from LTC₄-/S-hexyl-GSH-treated guinea pigs revealed air-trapping expansion, particularly at the alveolar site. Inhaled LTC₄ in conscious guinea pigs treated with S-hexyl GSH increased both airway resistance and airway hyperinflation. On the other hand, LTC₄-induced air-trapping was only partially suppressed by treatment with the bronchodilator salmeterol. Although montelukast inhibition of LTC₄-induced air-trapping was weak, treatment with BayCysLT₂RA resulted in complete suppression of this air-trapping. Furthermore, BayCysLT₂RA completely suppressed LTC₄-induced airway vascular hyperpermeability. In conclusion, we found in this study that CysLT₂ receptors mediate LTC₄-induced bronchoconstriction and air-trapping in S-hexyl GSH-treated guinea pigs. It is therefore believed that CysLT₂ receptors contribute to asthmatic response involving air-trapping.

Longitudinal study of effects of oral dosage of Bifidobacterium bifidum G9-1 on Japanese cedar pollen-induced allergic nasal symptoms in guinea pigs

Previous studies using experimental animal models have reported the beneficial effects of probiotics on allergic responses; however, their long-term effects on allergic nasal symptoms in clinical settings have not yet been elucidated in detail. In the present study, a guinea pig allergic rhinitis model involving repeated inhalation challenges with a natural allergen, Japanese cedar pollen, was used to examine the longitudinal effects of Bifidobacterium bifidum G9-1 (BBG9-1) on allergic nasal symptoms. BBG9-1 was administered orally once a day. Amelioration of nasal blockage was consistently observed throughout the experimental period in the BBG9-1-treated group. Although challenge-induced sneezing was not significantly inhibited in the BBG9-1-treated group, prolonged treatment with BBG9-1 slightly reduced the frequency of sneezing. Antigen-specific IgE antibody production was also not inhibited in the BBG9-1-treated group. Increases in the numbers of eosinophils and neutrophils in nasal cavity lavage fluid collected after pollen challenge were almost completely suppressed by BBG9-1 treatment, whereas those in mast cell mediators, histamine and cysteinyl leukotrienes were not. In contrast, increases in the levels of nitric oxide metabolites were potently suppressed. Furthermore, prolonged BBG9-1 treatment markedly suppressed exogenous leukotriene D4 -induced nasal blockage. Thus, prolonged oral administration of BBG9-1 suppresses Japanese cedar pollen-induced allergic nasal symptoms. The inhibitory mechanisms responsible may involve reductions in the responsiveness of target organs, such as endothelial cells in nasal mucosal blood vessels, to chemical mediators.

Dietary deficiencies of unsaturated fatty acids and starch cause atopic dermatitis-like pruritus in hairless mice

Hairless mice fed with a special diet (named HR-AD) show atopic dermatitis (AD)-like pruritic skin inflammation that is almost completely resolved with the supplementation of an unsaturated fatty acid (UFA), the linoleic acid (LA). This suggests that the dietary deficiency of LA is the key cause of this dermatitis. However, because there is no appropriate control diet for HR-AD, the involvement of other dietary ingredients cannot be ruled out. Furthermore, it has not yet been tested whether only UFA deficiency can cause such AD-like pruritus. In this study, using semi-purified custom diets, we attempted to reproduce this syndrome. Four-week-old hairless mice were maintained on a widely used standard diet American Institute of Nutrition-76A (AIN-76A), its modifications, or HR-AD. Several modifications of fat and carbohydrate components revealed that dietary deficiency of both UFAs and cornstarch was required to induce severe skin barrier dysfunction as typically occurred in HR-AD-fed mice. An UFA- and cornstarch-deficient diet caused severe AD-like pruritus comparable to HR-AD, despite weak Th2 immune responses and absence of immunoglobulin E production. On the other hand, a diet lacking UFAs but containing cornstarch significantly alleviated the development of pruritic dermatitis. Furthermore, the supplementation of wheat starch similarly improved skin barrier function. In conclusion, this study showed that a lack of certain starches might also be the cause of diet-induced AD. Our findings could help to reproduce the diet-induced AD itch model and also provide evidence that certain starches can have protective and ameliorative effects on AD-like pruritus.

Expression of CysLT2 receptors in asthma lung, and their possible role in bronchoconstriction

BACKGROUND

The expression and functional role of CysLT2 receptors in asthma have not been clarified. In this study, we evaluated CysLT2 receptors expression, and effects of CysLT2-and CysLT1/2-receptor antagonists on antigen-induced bronchoconstriction using isolated lung tissues from both asthma and non-asthma subjects.

METHODS

CysLT1 and CysLT2 receptors expression in asthma and non-asthma lung tissue preparations was examined in immunohistochemistry experiments, and their functional roles in antigen-induced bronchoconstriction were assessed using ONO-6950, a dual CysLT1/2-receptor antagonist, montelukast, a CysLT1 receptor antagonist, and BayCysLT2RA, a CysLT2 receptor-specific antagonist.

RESULTS

CysLT1 receptors were expressed on the bronchial smooth muscle and epithelium, and on alveolar leukocytes in 5 in 5 non-asthma subjects and 2 in 2 asthma subjects. On the other hand, although degrees of CysLT2 receptors expression were variable among the 5 non-asthma subjects, the expression in the asthma lung was detected on bronchial smooth muscle, epithelium and alveolar leukocytes in 2 in 2 asthma subjects. In the non-asthma specimens, antagonism of CysLT2 receptors did not affect antigen-induced bronchial contractions, even after pretreatment with the CysLT1-receptor specific antagonist, montelukast. However, in the bronchus isolated from one of the 2 asthma subjects, antagonism of CysLT2 receptors suppressed contractions, and dual antagonism of CysLT1 and CysLT2 receptors resulted in additive inhibitory effect on anaphylactic contractions.

CONCLUSIONS

CysLT2 receptors were expressed in lung specimens isolated from asthma subjects. Activation of CysLT2 receptors may contribute to antigen-induced bronchoconstriction in certain asthma population.

Thymic stromal lymphopoietin-induced interleukin-17A is involved in the development of IgE-mediated atopic dermatitis-like skin lesions in mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease associated with elevated levels of allergen-specific IgE. Although thymic stromal lymphopoietin (TSLP) and interleukin-17A (IL-17A) have been considered as important factors in allergic diseases, their relationships in AD have not been fully defined. Here, we show the contribution of TSLP-induced IL-17A responses to IgE-mediated AD-like skin lesions. BALB/c mice passively sensitized by intraperitoneal injections of ovalbumin (OVA)-specific IgE monoclonal antibody (mAb) were challenged with OVA applied to the skin six times. Treatment with anti-TSLP mAb during the second to sixth challenges inhibited IgE-mediated AD-like skin lesions and IL-17A production in lymph nodes. Furthermore, the increased number of IL-17A-producing CD4(+) and γδ T cells in lymph nodes and neutrophilic inflammation in the skin were reduced by anti-TSLP mAb. These findings prompted us to examine the roles of IL-17A. Treatment with anti-IL-17A mAb suppressed the AD-like skin lesions and neutrophilic inflammation; anti-Gr-1 mAb also inhibited them. Furthermore, treatment with CXCR2 antagonist reduced the AD-like skin lesions and neutrophilic inflammation accompanied by the reduction of IL-17A production; the increased CXCR2 expression in the epidermal cells was suppressed by anti-TSLP mAb. Meanwhile, these treatments, except for anti-Gr-1 mAb, inhibited the increased mast cell accumulation in the skin. Collectively, the mechanism of IgE mediating IL-17A-producing CD4(+) and γδ T cells through TSLP by repeated antigen challenges is involved in AD-like skin lesions associated with skin inflammation, such as neutrophil and mast cell accumulation; TSLP may regulate CXCR2 signalling-induced IL-17A production.

Discovery of Gemilukast (ONO-6950), a Dual CysLT1 and CysLT2 Antagonist As a Therapeutic Agent for Asthma

An orally active dual CysLT1 and CysLT2 antagonist possessing a distinctive structure which consists of triple bond and dicarboxylic acid moieties is described. Gemilukast (ONO-6950) was generated via isomerization of the core indole and the incorporation of a triple bond into a lead compound. Gemilukast exhibited antagonist activities with IC50 values of 1.7 and 25 nM against human CysLT1 and human CysLT2, respectively, and potent efficacy at an oral dose of 0.1 mg/kg given 24 h before LTD4 challenge in a CysLT1-dependent guinea pig asthmatic model. In addition, gemilukast dose-dependently reduced LTC4-induced bronchoconstriction in both CysLT1- and CysLT2-dependent guinea pig asthmatic models, and it reduced antigen-induced constriction of isolated human bronchi. Gemilukast is currently being evaluated in phase II trials for the treatment of asthma.

Semaphorin 7A plays a critical role in IgE-mediated airway inflammation in mice

Elevated allergen-specific IgE levels are a hallmark of allergic asthma, a disease involving chronic airway inflammation characterized by airway hyperresponsiveness (AHR); neutrophilic airway inflammation is found in patients with severe asthma. Furthermore, we have reported that interleukin (IL)-33 and IL-17A contribute to IgE-mediated AHR through neutrophilic inflammation in mice. Meanwhile, semaphorins regulating neuronal and immune function have been focused on in several diseases. Here, we investigated whether semaphorin 7A (SEMA7A) is related to IgE-mediated neutrophilic inflammation in mice. BALB/c mice sensitized with antigen-specific IgE monoclonal antibody were repeatedly challenged by the antigen. When anti-SEMA7A antibody was administered during the fourth to seventh challenges, the infiltration by macrophages, lymphocytes, neutrophils, and eosinophils in the lungs was reduced at the seventh challenge (P<0.05, 0.05, 0.01, and 0.05, respectively). However, the increased production of IL-4, IL-5, IL-13, IL-33, IL-17A, IL-6, and CXCL1 in the lungs was not suppressed. In histological analysis, the epithelial cells, blood vessels, and inflammatory cells in the lungs of IgE-sensitized mice showed SEMA7A expression; plexin C1 for the receptor was expressed in the inflammatory cells. Meanwhile, we examined the effect of anti-SEMA7A antibody on AHR and neutrophilic inflammation enhanced by the collaborative action of IL-33 and IL-17A in normal mice, resulting in the suppression of these responses (P<0.05 and 0.01, respectively). Collectively, we demonstrated that SEMA7A plays a critical role in IgE-mediated neutrophilic airway inflammation. Therefore, SEMA7A may be a potential therapeutic target for severe allergic asthma showing neutrophilic airway inflammation.

Production of interleukin (IL)-33 in the lungs during multiple antigen challenge-induced airway inflammation in mice, and its modulation by a glucocorticoid

Although interleukin (IL)-33 is a candidate aggravator of asthma, the cellular sources of IL-33 in the lungs during the progression of antigen-induced airway inflammation remain unclear. Furthermore, it has not been determined whether the antigen-induced production of IL-33 can be pharmacologically modulated in vivo. In this study, we examined the production of IL-33 in the lungs of sensitized mice during multiple intratracheal challenges with the antigen, ovalbumin. The 1st challenge clearly induced the IL-33 production in the lungs, and it was enhanced by the 2nd-4th challenges. IL-33 mRNA transcription was also induced after these challenges. An immunohistochemical analysis revealed that the cellular sources of IL-33 after the 1st challenge were mainly bronchial epithelial cells, while those after the 3rd challenge were not only the epithelial cells, but also inflammatory cells that infiltrated the lungs. Flow cytometric analyses indicated that approximately 20% and 10% of the IL-33-producing cells in the lungs were M2 macrophages and conventional dendritic cells, respectively. A systemic treatment with dexamethasone before the 1st challenge potently suppressed the IL-33 production. When dexamethasone was administered before the respective challenges, production of the IL-33 protein and the infiltration of IL-33-producing M2 macrophages and dendritic cells into the lungs in the 3rd challenge were also suppressed. In conclusion, the cellular sources of IL-33 in the lungs were dynamically altered during multiple challenges: not only bronchial epithelial cells, but also the M2 macrophages and dendritic cells that infiltrated the lungs produced IL-33. The production of IL-33 was susceptible to the glucocorticoid treatment.

IgE/antigen-mediated enhancement of IgE production is a mechanism underlying the exacerbation of airway inflammation and remodelling in mice

IgE is known to enhance some antibody responses to specific antigens, but whether this contributes to allergic asthma remains unclear. We have previously found that repeated antigen challenges in mice sensitized with antigen-specific IgE monoclonal antibody (mAb) exacerbated airway inflammation and remodelling accompanied by increased levels of endogenous antigen-specific IgE and IgG1. Here, we investigated whether IgE/antigen-mediated enhancement of endogenous IgE production contributes to the exacerbation of airway inflammation and remodelling. BALB/c mice passively sensitized with ovalbumin (OVA) -specific IgE mAb were challenged with OVA intratracheally seven times; anti-IgE mAb was intraperitoneally administered 1 day before the fourth challenge. Treatment with anti-IgE mAb inhibited the increased level of endogenous OVA-specific IgE in serum, but not OVA-specific IgG1, and a biphasic increase in airway resistance at the fourth challenge. Furthermore, a biphasic increase in airway resistance, airway hyper-responsiveness to methacholine, OVA-specific IgE and IgG1 production, and infiltrations by neutrophils and eosinophils in the lungs at the seventh challenge were suppressed by treatment; airway remodelling, such as goblet cell hyperplasia and sub-epithelial fibrosis, was also reduced. In addition, the production of interleukin-17A, interleukin-33 and CXCL1 in the lungs related to these IgE-mediated responses was decreased by treatment. Collectively, we found that the mechanism leading to the exacerbation of allergic asthma is closely related to IgE/antigen-mediated enhancement of IgE production, suggesting that this may create a vicious circle leading to the chronic status in asthmatic patients having levels of antigen-specific IgE ready to form complexes with antigen.

Roles of basophils and mast cells infiltrating the lung by multiple antigen challenges in asthmatic responses of mice

BACKGROUND AND PURPOSE

Mast cell hyperplasia has been observed in the lungs of mice with experimental asthma, but few reports have studied basophils. Here, we attempted to discriminate and quantify mast cells and basophils in the lungs in a murine asthma model, determine if both cells were increased by multiple antigen challenges and assess the roles of those cells in asthmatic responses.

EXPERIMENTAL APPROACH

Sensitized Balb/c mice were intratracheally challenged with ovalbumin four times. Mast cells and basophils in enzymatically digested lung tissue were detected by flow cytometry. An anti-FcεRI monoclonal antibody, MAR-1, was i.p. administered during the multiple challenges.

KEY RESULTS

The numbers of both mast cells (IgE(+) C-kit(+) ) and basophils (IgE(+) C-kit(-) CD49b(+) ) increased in the lungs after three challenges. Treatment with MAR-1 completely abolished the increases; however, a late-phase increase in specific airway resistance (sRaw), and airway eosinophilia and neutrophilia were not affected by the treatment, although the early-phase increase in sRaw was suppressed. MAR-1 reduced antigen-induced airway IL-4 production. Basophils infiltrating the lung clearly produced IL-4 after antigen stimulation in vitro; however, histamine and murine mast cell protease 1 were not increased in the serum after the challenge, indicating that mast cell activation was not evoked.

CONCLUSION AND IMPLICATIONS

Both mast cells and basophils infiltrated the lungs by multiple intratracheal antigen challenges in sensitized mice. Neither mast cells nor basophils were involved in late-phase airway obstruction, although early-phase obstruction was mediated by basophils. Targeting basophils in asthma therapy may be useful for an early asthmatic response.

Interleukin (IL)-33: new therapeutic target for atopic diseases

Interleukin (IL)-33, a member of the IL-1 family of cytokines, is produced when epithelial and endothelial cells are exposed to stimuli. Hematopoietic cells such as macrophages also produce IL-33. IL-33 is considered to function as an 'alarmin', activating various immune cells through its receptor ST2, which leads to the production of various molecules. The IL-33-induced production of pro-inflammatory cytokines is a critical event that aggravates atopic diseases such as asthma, atopic dermatitis, and pollenosis and suggests that IL-33-blocking agents could represent new therapeutic drugs. The anti-IL-33 antibody was effective in allergic models, whereas the anti-ST2 antibody has yielded controversial results because soluble ST2 functions as a decoy receptor for IL-33. IL-33-mediated pulmonary inflammation may be glucocorticoid-resistant especially when other cytokines act synergistically. Anti-tumor necrosis factor (TNF)-α therapy may also be effective against IL-33-mediated diseases. ERK1/2 inhibitors have also been shown to suppress the production of IL-33. On the other hand, activation of β2-receptors enhanced the expression of IL-33 mRNA in dendritic cells by activating protein kinase A (PKA), suggesting that PKA inhibitors may be candidates for IL-33-blocking agents. The effects of IL-33-blocking agents on atopic diseases need to be pharmacologically assessed in experimental and clinical studies.

IL-17A promotes the exacerbation of IL-33-induced airway hyperresponsiveness by enhancing neutrophilic inflammation via CXCR2 signaling in mice

Neutrophilic airway inflammation is a hallmark of patients with severe asthma. Although we have reported that both IL-33 and IL-17A contributed to IgE-mediated neutrophilic inflammation in mice, the relationship remains unclear. In this article, we examined how IL-17A modifies IL-33-induced neutrophilic inflammation and airway hyperresponsiveness (AHR). IL-33 was intratracheally administered to BALB/c mice on days 0-2; furthermore, on day 7, the effect of the combination of IL-33 and IL-17A was evaluated. Compared with IL-33 or IL-17A alone, the combination exacerbated neutrophilic inflammation and AHR, associated with more increased levels of lung glutamic acid-leucine-arginine(+) CXC chemokines, including CXCL1, CXCL2, and CXCL5, and infiltration by alveolar macrophages expressing CXCR2. Treatment with anti-CXCR2 mAb or depletion of alveolar macrophages repressed neutrophilic inflammation and AHR; in addition, depletion of neutrophils suppressed AHR. These findings prompted us to examine the role of CXCR2 in IgE-sensitized mice; a single treatment with anti-CXCR2 mAb in the seventh Ag challenge inhibited late-phase airway obstruction, AHR, and neutrophilic inflammation. In addition to inhibition, multiple treatments during the fourth to seventh challenge attenuated early-phase airway obstruction, eosinophilic inflammation, and goblet cell hyperplasia associated with the reduction of Th2 cytokine production, including IL-4, IL-5, and IL-13. Collectively, IL-33 cooperated with IL-17A to exacerbate AHR by enhancing neutrophilic inflammation via CXCR2 signaling; furthermore, CXCR2 signaling derived Th2 responses. We thus suggest the underlying mechanisms of IL-33 and IL-17A in allergic asthma and CXCR2 as potential therapeutic targets for the disease.

Interleukin-33 and alveolar macrophages contribute to the mechanisms underlying the exacerbation of IgE-mediated airway inflammation and remodelling in mice

Allergen-specific IgE has long been regarded as a major molecular component of allergic asthma. Additionally, there is increasing evidence of the important roles of interleukin-33 (IL-33) in the disease. Here, we show that IL-33 and alveolar macrophages play essential roles in the exacerbation of IgE-mediated airway inflammation and remodelling. BALB/c mice passively sensitized with ovalbumin (OVA)-specific IgE monoclonal antibody (mAb) were challenged with OVA seven times intratracheally. The seventh challenge exacerbated airway inflammation and remodelling compared with the fourth challenge; furthermore, markedly increased expression of IL-33 in the lungs was observed at the fourth and seventh challenges. When anti-IL-33 or anti-ST2 antibody was administered during the fourth to seventh challenge, airway inflammation and remodelling were significantly inhibited at the seventh challenge. Because increases of IL-33(+) and ST2(+) alveolar macrophages and ST2(+)  CD4(+) T cells in the lungs were observed at the fourth challenge, the roles of macrophages and CD4(+) cells were investigated. Depletion of macrophages by 2-chloroadenosine during the fourth to seventh challenge suppressed airway inflammation and remodelling, and IL-33 production in the lung at the seventh challenge; additionally, anti-CD4 mAb inhibited airway inflammation, but not airway remodelling and IL-33 production. Meanwhile, treatment with 2-chloroadenosine or anti-CD4 mAb decreased IL-33-induced airway inflammation in normal mice; airway remodelling was repressed only by 2-chloroadenosine. These results illustrate that macrophage-derived IL-33 contributes to the exacerbation of IgE-mediated airway inflammation by mechanisms associated with macrophages and CD4(+) cells, and airway remodelling through the activation of macrophages.

Involvement of chymase in allergic conjunctivitis of guinea pigs

It has been reported that chymase activity was increased in allergic conjunctivitis patients and this activity was correlated with the severity of the disease. However, the precise roles of chymase in allergic conjunctivitis are unclear, and whether chymase inhibitors are effective for allergic conjunctivitis has not been reported even in experimental animal models. In this study, the roles of chymase in the pathogenesis were evaluated using a selective chymase inhibitor, ONO-WH-236, in a guinea pig model of allergic conjunctivitis induced by cedar pollen. Sensitized guinea pigs were challenged by the pollen, followed by assessing redness and edema in the conjuntiva, and counting the frequency of eye scratching as an itch-associated response. Treatment with the ONO-WH-236 (40 and 80 mg/kg, p.o.) dose-dependently inhibited the induction of redness, edema and scratching behavior. An anti-histaminic drug, ketotifen (3 mg/kg, p.o.), also significantly inhibited conjunctivitis symptoms. Chymase activity was increased in ophthalmic lavage fluid immediately after the pollen challenge. The increase in chymase activity was inhibited by in vivo treatment with ONO-WH-236. Interestingly, increased histamine in the ophthalmic lavage fluid immediately after the challenge was also inhibited by the chymase inhibitor. Administration of human recombinant chymase by eye dropping (0.09 and 0.9 μg/eye) dose-dependently induced scratching behavior, which was inhibited by not only ONO-WH-236 but also ketotifen; however, chymase administration induced only weak redness in the conjunctiva, which was resistant to treatment with anti-histaminic drugs. In conclusion, it was suggested that chymase was released from mast cells after antigen challenge, followed by the induction of conjunctivitis symptoms through histamine release from mast cells. Thus, chymase could be a potential target for pharmacotherapy for allergic conjunctivitis.

Exposure to multiwalled carbon nanotubes and allergen promotes early- and late-phase increases in airway resistance in mice

The facilitating effects of multiwalled carbon nanotubes (MWCNT) on allergic asthma have not been sufficiently examined, although MWCNT appear to significantly increase the risk of health problems from occupational or environmental exposure. In this study, we examined whether sensitization by the combination of MWCNT with ovalbumin (OVA) promotes allergic asthmatic responses. BALB/c mice administered vehicle, MWCNT, OVA, or MWCNT+OVA through an intranasal route were challenged with OVA intratracheally four times. In the MWCNT+OVA group, the fourth challenge caused not only early- but also late-phase increases in airway resistance, although these responses were not observed in the vehicle, MWCNT, or OVA group; furthermore, the extents of the early and late responses were comparable to those in mice systemically sensitized with OVA+alum. Sensitization with MWCNT and OVA promoted airway inflammation and goblet cell hyperplasia in the lung compared with the vehicle, MWCNT or OVA group. In addition, adjuvant activity for OVA-specific immunoglobulin E (IgE), IgG1, and IgG2a production in serum and increased levels of interleukin-4 (IL-4), IL-5, IL-13, and IL-17 in the lung tissue were observed. In conclusion, these results suggest that exposure to MWCNT and antigen can induce a biphasic increase in airway resistance, airway inflammation, goblet cell hyperplasia, and the production of antigen-specific antibodies. This study highlights the risk of exposure to a combination of MWCNT with antigen.

Effect of a peroxynitrite scavenger, a manganese-porphyrin compound on airway remodeling in a murine asthma

Airway remodeling, pathological changes in the lung structure, is a characteristic feature of chronic asthma. The changes include bronchial epithelial hyperplasia and hypertrophy, excess production of mucus, and fibroblast proliferation in the lung. On the other hand, it has been known that both nitric oxide and superoxide anion are increased in exhaled air of asthmatic patients. These molecules react with each other forming a powerful oxidant, peroxynitrite. In this study, effect of a peroxynitrite scavenger, a metalloporphyrin compound, [tetrakis(4-carboxylatophenyl)porphyrinato]manganese(III) (MnTBAP) on multiple antigen challenge-induced airway remodeling was evaluated in mice. When sensitized BALB/c mice were intratracheally challenged with an antigen, ovalbumin, for 3 times, bronchial epithelial thickening and mucus accumulation in the epithelium were histologically observed. Daily treatment with MnTBAP (3, 10 mg/kg/time/twice a day, intraperitoneally (i.p.)) dose-dependently suppressed both the epithelial thickening and mucus accumulation in the epithelium. On the other hand, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining revealed that the multiple antigen challenges increased the number of apoptotic cells in the bronchial epithelium. The increase in apoptotic cells was also effectively suppressed by the treatment with MnTBAP. Taken together, it was suggested that peroxynitrite could be involved in the formation of epithelial hyperplasia associated with the mucus accumulation through induction of apoptosis of the epithelial cells. Thus, peroxynitrite can be a target molecule for development of new pharmacotherapy for asthma.