Foxp3(+)-Treg cells enhanced by repeated low-dose gamma-irradiation attenuate ovalbumin-induced allergic asthma in mice

The Hormesis Concept: Strengths and Shortcomings

Hormesis implies that the effects of various materials or conditions that organisms are exposed to, may not have linear dose-response characteristics but rather, can be biphasic. Thus the response to a low dose of a stressor may be the opposite to that occurring at higher doses. Such a dual response is postulated for many toxicants and physical conditions and may involve a beneficial adaptive response. Such a non-linear effect is undoubtedly present in many useful pharmacological and nutraceutical agents with can be toxic at high concentrations. This somewhat divisive topic is an area of study that should be objectively studied and not clouded by political and policy considerations. The objective of this review is to examine claims concerning those exposures where hormesis seems to exist and also those where there is no good supporting evidence. The breadth of this phenomenon and potential mechanisms underlying hormetic events are discussed together with their limitations.

Regulatory effects of miRNA-126 on Th cell differentiation and cytokine expression in allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is a common disease worldwide. Imbalances in T helper (Th) cell differentiation and the dysregulation of related cytokines form the immunological basis of AR. miR-126 may play an important regulatory role in AR as a new marker and predictor of the disease. Therefore, the aim of this study was to explore the regulatory effects of miR-126 on Th cell differentiation and cytokine expression in AR.

METHODS

T lymphocytes and rat models were transfected with a miR-126 mimic and an inhibitor. The expression of miR-126 and Th cell-related cytokines was detected by RT-qPCR and western blotting. The serum IgE levels were detected using ELISA. In the nasal mucosa, pathological changes were observed by HE staining, protein expression was detected by immunohistochemistry, and the differentiation ratio of Th cell subsets was detected by flow cytometry.

RESULTS

During the occurrence and development of AR, the expression of miR-126 and the IgE levels were increased in the AR group. The number of Treg cell subsets decreased in the AR rats, increased after the miR-126 agomir intervention and decreased after miR-126 antagomir intervention. The number of Th1 and Th2 cell subsets increased in the AR rats, decreased after miR-126 agomir intervention and increased after the miR-126 antagomir intervention.

CONCLUSION

We propose that miR-126 may be involved in the pathogenesis of AR by positively regulating the expression of Treg cytokines and negatively regulating the expression of the Th1 and Th2 cytokines.

Low Dose Rate Radiation Regulates M2-like Macrophages in an Allergic Airway Inflammation Mouse Model

We investigated the effects of low dose rate radiation (LDR) on M1 and M2 macrophages in an ovalbumin-induced mouse model of allergic airway inflammation and asthma. After exposure to LDR (1 Gy, 1.818 mGy/h) for 24 days, mice were euthanized and the changes in the number of M1 and M2 macrophages in the bronchoalveolar lavage fluid and lung, and M2-associated cytokine levels, were assessed. LDR treatment not only restored the M2-rich microenvironment but also ameliorated asthma-related progression in a macrophage-dependent manner. In an ovalbumin-induced mouse model, LDR treatment significantly inhibited M2, but not M1, macrophage infiltration. M2-specific changes in macrophage polarization during chronic lung disease reversed the positive effects of LDR. Moreover, the levels of cytokines, including chemokine (C-C motif) ligand (CCL) 24, CCL17, transforming growth factor beta 1, and matrix metalloproteinase-9, decreased in ovalbumin-sensitized/challenged mice upon exposure to LDR. Collectively, our results indicate that LDR exposure suppressed asthmatic progression, including mucin accumulation, inflammation, and Type 2 T helper (Th2) cytokine (interleukin (IL)-4 and IL-13) production. In conclusion, LDR exposure decreased Th2 cytokine secretion in M2 macrophages, resulting in a reduction in eosinophilic inflammation in ovalbumin-sensitized/challenged mice.

Exposure to Low to Moderate Doses of Ionizing Radiation Induces A Reduction of Pro-Inflammatory Ly6chigh Monocytes and a U-Curved Response of T Cells in APOE -/- Mice

Low dose ionizing radiation (LDIR) is known to have a protective effect on atherosclerosis in rodent studies, but how it impacts different cells types involved in lesion formation remains incompletely understood. We investigated the immunomodulatory response of different doses and dose-rates of irradiation in ApoE^-/- mice. Mice were exposed to external γ rays at very low (1.4 mGy.h^-1) or low (50 mGy.h^-1) dose-rates, with cumulative doses spanning 50 to 1000 mGy. Flow cytometry of circulating cells revealed a significant decrease in pro-inflammatory Ly6C^Hi monocytes at all cumulative doses at low dose-rate, but more disparate effects at very low dose-rate with reductions in Ly6C^Hi cells at doses of 50, 100 and 750 mGy only. In contrast, Ly6C^Lo monocytes were not affected by LDIR. Similarly, proportions of CD4⁺ T cell subsets in the spleen did not differ between irradiated mice and non-irradiated controls, whether assessing CD25⁺FoxP3⁺ regulatory or CD69⁺ activated lymphocytes. In the aorta, gene expression of cytokines such as IL-1 and TGF-ß and adhesion molecules such as E-Selectin, ICAM-1, and VCAM-1 were reduced at the intermediate dose of 200 mGy. These results suggest that LDIR may reduce atherosclerotic plaque formation by selectively reducing blood pro-inflammatory monocytes and by impairing adhesion molecule expression and inflammatory processes in the vessel wall. In contrast, splenic T lymphocytes were not affected by LDIR. Furthermore, some responses to irradiation were nonlinear; reductions in aortic gene expression were significant at intermediate doses, but not at either highest or lowest doses. This work furthers our understanding of the impact of LDIR with different dose-rates on immune system response in the context of atherosclerosis.

Preventative and Therapeutic Effects of Low-dose Ionizing Radiation on the Allergic Response of Rat Basophilic Leukemia Cells

The prevalence of allergies has increased over the last four decades. In allergic reactions, mast cells induce a hypersensitive immune response to a substance that is normally harmless. Ionizing radiation has different biological effects depending on the dose and dose rate. In this study, we investigated whether low-dose irradiation before (preventative effect) or after (therapeutic effect) an antigen-antibody reaction has an anti-allergic effect. To test this, we activated rat basophilic leukemia (RBL-2H3) mast cells with anti-2,4-dinitrophenyl IgE (antibody) and 2,4-dinitrophenyl human serum albumin, which served as an antigen. To test for both the potential of a preventative effect and a therapeutic effect, we irradiated mast cells both before and after mast cell activation, and we measured mediator release and signaling pathway activity. Low-dose ionizing radiation suppressed mediator release from RBL-2H3 mast cells activated by the antigen-antibody reaction regardless of when the mast cells were irradiated. These results were due to the suppression of FcεRI expression. Therefore, we suggest that low-dose ionizing radiation has a preventative and therapeutic effect in allergic reactions via the FcεRI-mediated RBL-2H3 mast cell activation system.

Regulatory T cells regulate the distribution of natural killer T cells through CD39 signal transduction in asthma

Natural killer T cells (NKT cells) and regulatory T cells (Treg cells) are two important immune regulatory cells which both play critical roles in asthma. Our previous experiments revealed that activation of Treg cells suppressed NKT cells in asthma. However, the possible regulatory effects and the mechanisms linking Treg cells and NKT cells remain poorly understood. The current study was designed to further investigate the regulatory effect and its possible mechanisms of Treg cells on NKT cells function, especially the distribution of NKT cells. Regulatory T cell (Treg), responder T cell (Teff) and Natural killer T cell (NKT) were isolated and purified. After Lentivirus carrying CD39 (Le-CD39) was transfected into Treg cells, the immune phenotype of Treg cells was changed and the suppressive effect of Treg cells on Teff cells with an activation of Treg cells was enhanced, marking with a high expression level of interleukin 10 (IL-10) and transforming growth factor β (TGF-β). Up-regulation of CD39 expression led to lower ATP level in cell culture supernatant. To further explore its function in asthma, we introduced an ovalbumin (OVA)-induced mice model of asthma. And the data showed that up-regulation of CD39 remarkably alleviated OVA-induced hallmarks of the asthma and increased NKT cells in the spleen and peripheral blood; however, decreased NKT cells in the lung. Furthermore, up-regulation of CD39 decreased the levels of interleukin 4 (IL-4) and interferon γ (IFN-γ) in the lung of OVA-treated mice. Our results strongly suggest that Treg cells could be activated by CD39 signal transduction and then affected the distribution of NKT cells in the OVA-induced mice model of asthma.

IL‐35, a hallmark of immune‐regulation in cancer progression, chronic infections and inflammatory diseases

Cytokine members of the IL‐12 family have attracted enormous attention in the last few years, with IL‐35 being the one of the most attractive‐suppressive cytokine. IL‐35 is an important mediator of regulatory T cell function. Regulatory T cells play key roles in restoring immune homeostasis after facing challenges such as infection by specific pathogens. Moreover, a crucial role for regulatory T cell populations has been demonstrated in several physiological processes, including establishment of fetal–maternal tolerance, maintenance of self‐tolerance and prevention of autoimmune diseases. However, a deleterious involvement of immune regulatory T cells has been documented in specific inhibition of immune responses against tumor cells, promotion of chronic infections and establishment of chronic inflammatory disorders. In this review, we attempt to shed light on the concept of immune‐homoeostasis on the aforementioned issues, taking IL‐35 as the hallmark of regulatory responses. The dilemma between immune‐mediated cancer treatment and inflammation is discussed. Histopathological indications of chronic vs. acute infections are elaborated. Moreover, the evidence that IL‐35 requires additional immune‐regulatory cytokines, such as IL‐10 and TGF‐β, to induce effective and maximal anti‐inflammatory effects suggest that immune‐regulation requires multi‐factorial analysis of many immune playmakers rather than a specific immune target.

Th17/Treg homeostasis, but not Th1/Th2 homeostasis, is implicated in exacerbation of human bronchial asthma

Background

Th17 and regulatory T cell (Treg) play crucial roles in the pathogenesis of asthma. However, the association between Th17/Treg homeostasis and asthma exacerbation remains unclear.

Patients and methods

To investigate the role of Th17/Treg bias in asthma exacerbation, 49 asthma patients were enrolled in the current study, of whom 31 had acute asthma exacerbation (exacerbation group) and 18 did not (non-exacerbation group). Meanwhile, 17 healthy subjects were recruited as normal controls (control group). By measuring interleukin (IL)-4, IL-13, interferon (IFN)-γ, IL-10, and IL-17A levels in plasma using enzyme-linked immunosorbent assay (ELISA) and determining the mRNA expression of T-bet, GATA-3, forkhead/winged helix transcription factor (Foxp3), and receptor-related orphan receptor γt (RORγt) in peripheral blood mononuclear cells (PBMCs) by quantitative real-time PCR.

Results

We found that IL-17A/IL-10 and RORγt/Foxp3 ratios were significantly increased in the exacerbation group compared with that in the non-exacerbation group, while IL-4/IFN-γ and GATA-3/T-bet ratios remained unchanged. Moreover, IL-17A/IL-10 and RORγt/Foxp3 ratios, but not IL-4/IFN-γ or GATA-3/T-bet ratios, negatively correlated with forced expiratory volume in the first second (FEV₁)/FEV_1pred and Asthma Control Test Questionnaire (ACT) scores in both exacerbation group and non-exacerbation group. In contrast, the IL-4/IFN-γ ratio was negatively correlated with FEV₁/FEV_1pred and ACT scores only in the non-exacerbation group but not in the exacerbation group, while the ratio of GATA-3/T-bet was correlated with neither FEV₁/FEV_1pred nor ACT scores in both groups with asthma.

Conclusion

Our results suggest that the homeostasis of the Treg and Th17 cells is broken in asthma exacerbation and correlates with asthma severity and disease control status. The outcome has significant implication in understanding the progression of asthma and providing helpful information for physicians in the diagnosis and treatment of asthma patients.

Gamma Low-Dose-Rate Ionizing Radiation Stimulates Adaptive Functional and Molecular Response in Human Aortic Endothelial Cells in a Threshold-, Dose-, and Dose Rate-Dependent Manner

A central question in radiation protection research is whether low-dose and low-dose-rate (LDR) exposures to ionizing radiation play a role in progression of cardiovascular disease. The response of endothelial cells to different LDR exposures may help estimate risk of cardiovascular disease by providing the biological mechanism involved. We investigated the effect of chronic LDR radiation on functional and molecular responses of human aorta endothelial cells (HAoECs). Human aorta endothelial cells were continuously irradiated at LDR (6 mGy/h) for 15 days and analyzed at time points when the cumulative dose reached 0.05, 0.5, 1.0, and 2.0 Gy. The same doses were administered acutely at high-dose rate (HDR; 1 Gy/min). The threshold for the loss of angiogenic capacity for both LDR and HDR radiations was between 0.5 and 1.0 Gy. At 2.0 Gy, angiogenic capacity returned to normal only for HAoEC exposed to LDR radiation, associated with increased expression of antioxidant and anti-inflammatory genes. Pre-LDR, but not pre-HDR, radiation, followed by a single acute 2.0 Gy challenge dose sustained the expression of antioxidant and anti-inflammatory genes and stimulated angiogenesis. Our results suggest that dose rate is important in cellular response and that a radioadaptive response is involved for a 2.0 Gy dose at LDR.

Crucial role of OX40/OX40L signaling in a murine model of asthma

The aim of the present study was to explore the roles of OX40/OX40 ligand (OX40L) signaling and OX40⁺ T cells in ovalbumin (OVA)-induced mouse asthma model. Asthma was induced by OVA exposure and subsequent co-treatment with OX40L protein, neutralizing anti-OX40L blocking antibody, OX40⁺ T cells or PBS. The protein expression levels of interleukin (IL)-4, IL-6, IL-13, IL-17, tumor necrosis factor (TNF)-α and interferon (IFN)-γ in bronchoalveolar lavage fluid (BALF) were examined using murine cytokine-specific ELISA. Eosinophil accumulation as well as proliferation and apoptosis of T cells in BALF were detected by Cell Counting kit-8 and flow cytometric assays. Expression of the apoptosis-related protein cleaved caspase-3 was examined in OX40⁺ T cells using western blot assay. Flow cytometric analysis revealed that OVA-treated mice that were co-treated with OX40L or OX40⁺ T cells exhibited higher eosinophil infiltration compared with control mice treated only with OVA, whereas neutralizing anti-OX40L blocking antibody inhibited eosinophil infiltration. ELISA assays demonstrated that the expression of IL-4, IL-6, IL-13, IL-17, TNF-α and IFN-γ in BALF in OX40L-treated and OX40⁺ T cell-treated mice was increased compared with expression levels in control mice. Treatment with OX40L protein effectively reduced apoptosis of T cells and the expression of cleaved caspase-3 in T cells. OX40L-treated and OX40⁺ T cell-treated mice exhibited increased asthma through OX40/OX40L signaling, which probably promoted inflammatory factor expression, eosinophil infiltration and T cell proliferation.

Chinese herbal medicine formula Gu-Ben-Fang-Xiao-Tang attenuates airway inflammation by modulating Th17/Treg balance in an ovalbumin-induced murine asthma model

Gu-Ben-Fang-Xiao-Tang (GBFXT) is a traditional Chinese medicine formula consisting of 11 medicinal plants, which has been used in the treatment of asthma. The present study aimed to determine the protective effects and the underlying mechanisms of GBFXT on ovalbumin (OVA)-induced allergic inflammation in a mouse model of allergic asthma. A total of 50 mice were randomly assigned to the following five experimental groups: Normal, model, montelukast (2.6 mg/kg), 12 g/kg GBFXT and 36 g/kg GBFXT groups. Airway responsiveness was measured using the forced oscillation technique, while differential cell count in the bronchoalveolar lavage fluid (BALF) was measured by Wright-Giemsa staining. Histological assessment was performed by hematoxylin and eosin staining, while BALF levels of Th17/Treg cytokines were measured by enzyme-linked immunosorbent assay, and the proportions of Th17 and Treg cells were evaluated by flow cytometry. The results showed that GBFXT suppressed airway hyperresponsiveness during methacholine-induced constriction, reduced the percentage of leukocytes and eosinophils, and resulted in decreased absolute neutrophil infiltration in lung tissue. In addition, GBFXT treatment significantly decreased the IL-17A cytokine level and increased the IL-10 cytokine level in the BALF. Furthermore, GBFXT significantly suppressed Th17 cells and increased Treg cells in asthmatic mice. In conclusion, the current results demonstrated that GBFXT may effectively inhibit the progression of airway inflammation in allergic asthma, partially by modulating the Th17/Treg cell balance.

Inhibition of Asthma in OVA Sensitized Mice Model by a Traditional Uygur Herb Nepeta bracteata Benth

Asthma is a chronic lung inflammation which affects many people. As current therapies for asthma mainly rely on administration of glucocorticoids and have many side effects, new therapy is needed. In this study, we investigated Nepeta bracteata Benth., a traditional Uygur Herb, for its therapeutics effect in OVA induced asthmatic mice model. Treatment of OVA sensitized asthma mice with extract from Nepeta bracteata Benth. demonstrated improved lung pathology, as well as reduced infiltration of eosinophil and neutrophil. Nepeta bracteata Benth. extract also contributed to the rebalance of Th17/Treg cell via decreasing the Th17 cell and increasing the Treg, which was corresponding with the inhibited Th17 cytokine response and increased IL-10 level. Moreover, the reduced TGF-β level and Smad2/3 protein level also suggested that Nepeta bracteata Benth. extract could inhibit TGF-β mediated airway remodelling as well. Taken together, these data suggested that Nepeta bracteata Benth. may be a novel candidate for future antiasthma drug development.

Continuous Exposure to Low-Dose-Rate Gamma Irradiation Reduces Airway Inflammation in Ovalbumin-Induced Asthma

Although safe doses of radiation have been determined, concerns about the harmful effects of low-dose radiation persist. In particular, to date, few studies have investigated the correlation between low-dose radiation and disease development. Asthma is a common chronic inflammatory airway disease that is recognized as a major public health problem. In this study, we evaluated the effects of low-dose-rate chronic irradiation on allergic asthma in a murine model. Mice were sensitized and airway-challenged with ovalbumin (OVA) and were exposed to continuous low-dose-rate irradiation (0.554 or 1.818 mGy/h) for 24 days after initial sensitization. The effects of chronic radiation on proinflammatory cytokines and the activity of matrix metalloproteinase-9 (MMP-9) were investigated. Exposure to low-dose-rate chronic irradiation significantly decreased the number of inflammatory cells, methylcholine responsiveness (PenH value), and the levels of OVA-specific immunoglobulin E, interleukin (IL)-4, and IL-5. Furthermore, airway inflammation and the mucus production in lung tissue were attenuated and elevated MMP-9 expression and activity induced by OVA challenge were significantly suppressed. These results indicate that low-dose-rate chronic irradiation suppresses allergic asthma induced by OVA challenge and does not exert any adverse effects on asthma development. Our findings can potentially provide toxicological guidance for the safe use of radiation and relieve the general anxiety about exposure to low-dose radiation.

Chronic Internal Exposure to Low Dose 137Cs Induces Positive Impact on the Stability of Atherosclerotic Plaques by Reducing Inflammation in ApoE-/- Mice

After Chernobyl and Fukushima Daï Chi, two major nuclear accidents, large amounts of radionuclides were released in the environment, mostly caesium 137 (137Cs). Populations living in contaminated territories are chronically exposed to radionuclides by ingestion of contaminated food. However, questions still remain regarding the effects of low dose ionizing radiation exposure on the development and progression of cardiovascular diseases. We therefore investigated the effects of a chronic internal exposure to 137Cs on atherosclerosis in predisposed ApoE-/- mice. Mice were exposed daily to 0, 4, 20 or 100 kBq/l 137Cs in drinking water, corresponding to range of concentrations found in contaminated territories, for 6 or 9 months. We evaluated plaque size and phenotype, inflammatory profile, and oxidative stress status in different experimental groups. Results did not show any differences in atherosclerosis progression between mice exposed to 137Cs and unexposed controls. However, 137Cs exposed mice developed more stable plaques with decreased macrophage content, associated with reduced aortic expression of pro-inflammatory factors (CRP, TNFα, MCP-1, IFNγ) and adhesion molecules (ICAM-1, VCAM-1 and E-selectin). Lesions of mice exposed to 137Cs were also characterized by enhanced collagen and smooth muscle cell content, concurrent with reduced matrix metalloproteinase MMP8 and MMP13 expression. These results suggest that low dose chronic exposure of 137Cs in ApoE-/- mice enhances atherosclerotic lesion stability by inhibiting pro-inflammatory cytokine and MMP production, resulting in collagen-rich plaques with greater smooth muscle cell and less macrophage content.

The effect of ionizing radiation on regulatory T cells in health and disease

Treg cells are key elements of the immune system which are responsible for the immune suppressive phenotype of cancer patients. Interaction of Treg cells with conventional anticancer therapies might fundamentally influence cancer therapy response rates. Radiotherapy, apart from its direct tumor cell killing potential, has a contradictory effect on the antitumor immune response: it augments certain immune parameters, while it depresses others. Treg cells are intrinsically radioresistant due to reduced apoptosis and increased proliferation, which leads to their systemic and/or intratumoral enrichment. While physiologically Treg suppression is not enhanced by irradiation, this is not the case in a tumorous environment, where Tregs acquire a highly suppressive phenotype, which is further increased by radiotherapy. This is the reason why the interest for combined radiotherapy and immunotherapy approaches focusing on the abrogation of Treg suppression has increased in cancer therapy in the last few years. Here we summarize the basic mechanisms of Treg radiation response both in healthy and cancerous environments and discuss Treg-targeted pre-clinical and clinical immunotherapy approaches used in combination with radiotherapy. Finally, the discrepant findings regarding the predictive value of Tregs in therapy response are also reviewed.

IgE and IgA produced by OX40-OX40L or CD40-CD40L interaction in B cells-mast cells re-activate FcεRI or FcαRI on mast cells in mouse allergic asthma

Mast cells are major effector cells of allergic diseases related to IgE. This study was undertaken to determine whether IgE or IgA, produced by CD40-CD40L or OX40-OX40L interactions between B cells and mast cells, re-activate FcεRI or FcαRI on mast cell surface. C57BL mice were sensitized and subjected to OVA challenge to induce asthma. Bone marrow-derived mast cells (BMMCs) and primary B cells were co-cultured. Mast cell recruitment into airways was stained by May-Grünwald Giemsa, the expression of markers or signaling molecules were determined by immunohistochemistry or Western blotting, and co-localization of B cells and mast cells by immunofluorescence. Anti-CD40 plus anti-OX40L Abs synergistically reduced IgE and IgA production, and mediators (histamine, LTs and cytokines) released in mast cells, and additively reduced other responses, such as, numbers of mast cells, the expression of markers (tryptase, mMCP5, B220 and CD19), surface molecules (CD40, CD40L, OX40 and OX40L), FcεRI or FcαRI and the co-localization of BMMCs and B cells, and IgE- or IgA-producing cells, as compared with individual blocking Ab treatment which reducedresponses in BAL cells or lung tissues of OVA-challenged mice or in co-culture of B and mast cells. The data suggest that IgE and IgA, produced by OX40-OX40L or CD40-CD40L interaction between B cells and mast cells, may re-activate receptors of FCεRI and FcαRI on mast cell surfaces, followed by more mediator release, and furthermore, that treatment with anti-CD40 plus anti-OX40L Abs offers a potential treatment for allergic asthma.

Radiation-hormesis phenotypes, the related mechanisms and implications for disease prevention and therapy

Humans are continuously exposed to ionizing radiation throughout life from natural sources that include cosmic, solar, and terrestrial. Much harsher natural radiation and chemical environments existed during our planet's early years. Mammals survived the harsher environments via evolutionarily-conserved gifts ̶ a continuously evolving system of stress-induced natural protective measures (i.e., activated natural protection [ANP]). The current protective system is differentially activated by stochastic (i.e., variable) low-radiation-dose thresholds and when optimally activated in mammals includes antioxidants, DNA damage repair, p53-related apoptosis of severely-damaged cells, reactive-oxygen-species (ROS)/reactive-nitrogen-species (RNS)- and cytokine-regulated auxiliary apoptosis that selectively removes aberrant cells (e.g., precancerous cells), suppression of disease promoting inflammation, and immunity against cancer cells. The intercellular-signaling-based protective system is regulated at least in part via epigenetic reprogramming of adaptive-response genes. When the system is optimally activated, it protects against cancer and some other diseases, thereby leading to hormetic phenotypes (e.g., reduced disease incidence to below the baseline level; reduced pain from inflammation-related problems). Here, some expressed radiation hormesis phenotypes and related mechanisms are discussed along with their implications for disease prevention and therapy.

Effects of low-dose-gamma rays on the immune system of different animal models of disease

We reviewed the beneficial or harmful effects of low-dose ionizing radiation on several diseases based on a search of the literature. The attenuation of autoimmune manifestations in animal disease models irradiated with low-dose γ-rays was previously reported by several research groups, whereas the exacerbation of allergic manifestations was described by others. Based on a detailed examination of the literature, we divided animal disease models into two groups: one group consisting of collagen-induced arthritis (CIA), experimental encephalomyelitis (EAE), and systemic lupus erythematosus, the pathologies of which were attenuated by low-dose irradiation, and another group consisting of atopic dermatitis, asthma, and Hashimoto's thyroiditis, the pathologies of which were exacerbated by low-dose irradiation. The same biological indicators, such as cytokine levels and T-cell subpopulations, were examined in these studies. Low-dose irradiation reduced inter-feron (IFN)-gamma (γ) and interleukin (IL)-6 levels and increased IL-5 levels and the percentage of CD4(+)CD25(+)Foxp3(+)Treg cells in almost all immunological disease cases examined. Variations in these biological indicators were attributed to the attenuation or exacerbation of the disease's manifestation. We concluded that autoimmune diseases caused by autoantibodies were attenuated by low-dose irradiation, whereas diseases caused by antibodies against external antigens, such as atopic dermatitis, were exacerbated.

Expression of airway remodeling proteins in mast cell activated by TGF-β released in OVA-induced allergic responses and their inhibition by low-dose irradiation or 8-oxo-dG

Allergic asthma is characterized by chronic airway remodeling, which is associated with the expression of extracellular matrix proteins (ECM) by TGF-β. However, to date there are no reports demonstrating that structural proteins are directly expressed in mast cells. This study aimed to investigate whether ECM proteins are expressed in mast cells activated with antigen/antibody reaction, and whether the resolution effects of irradiation or 8-oxo-dG may contribute to allergic asthma prevention. Bone marrow-derived mast cells (BMMCs) were activated with DNP-HSA/anti-DNP IgE antibody (act-BMMCs). C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) to induce allergic asthma. Mice were treated orally with 8-oxo-dG or exposed to whole body irradiation (using (137)Cs gamma ray at a dose of 0.5 Gy) for three consecutive days 24 h after OVA challenge. Expression of extracellular matrix (ECM) proteins, TGF-β signaling molecules and NF-κB/AP-1 was determined in the BMMCs, bronchoalveolar lavage (BAL) cells or lung tissues using Western blot, polymerase chain reaction (PCR) and electrophoretic mobility shift assay (EMSA), respectively. Act-BMMCs increased expression of ECM proteins, TGF-β/TGF-β receptor I, TGF-β signaling molecules and cytokines; and increased both NF-κB and AP-1 activity. In addition, the population of mast cells; expression of mast cell markers, TGF-β signaling molecules, ECM proteins/amounts; OVA-specific serum IgE level; numbers of goblet cells; airway hyperresponsiveness; cytokines/chemokines were increased in BAL cells and lung tissues of OVA-challenged mice. All of the above end points were reduced by irradiation or 8-oxo-dG in vitro and in vivo, respectively. The data suggest that mast cells induce expression of ECM proteins through TGF-β produced in inflammatory cells of OVA mice and that post treatment of irradiation or 8-oxo-dG after OVA-challenge may reduce airway remodeling through down-regulating mast cell re-activation by TGF-β/Smad signals.