Effect of IL-15 addition on asbestos-induced suppression of human cytotoxic T lymphocyte induction.

BACKGROUND: Asbestos fibers possess tumorigenicity and are thought to cause mesothelioma. We have previously reported that exposure to asbestos fibers causes a reduction in antitumor immunity. Asbestos exposure in the mixed lymphocyte reaction (MLR) showed suppressed induction of cytotoxic T lymphocytes (CTLs), accompanied by a decrease in proliferation of CD8+ T cells. Recently, we reported that asbestos-induced suppression of CTL induction is not due to insufficient levels of interleukin-2 (IL-2). In this study, we continue to investigate the mechanism responsible for the effect of asbestos fibers on the differentiation of CTLs and focus on interleukin-15 (IL-15) which is known to be a regulator of T lymphocyte proliferation. METHODS: For MLR, human peripheral blood mononuclear cells (PBMCs) were cultured with irradiated allogenic PBMCs upon exposure to chrysotile B asbestos at 5 µg/ml for 7 days. After 2 days of culture, IL-15 was added at 1 ng/ml. After 7 days of MLR, PBMCs were collected and analyzed for phenotypic and functional markers of CD8+ T cells with fluorescence-labeled anti-CD3, anti-CD8, anti-CD45RA, anti-CD45RO, anti-CD25, and anti-granzyme B antibodies using flow cytometry. To examine the effect of IL-15 on the expression level of intracellular granzyme B in proliferating and non-proliferating CD8+ lymphocytes, PBMCs were stained using carboxyfluorescein diacetate succinimidyl ester (CFSE) and then washed and used for the MLR. RESULTS: IL-15 addition partially reversed the decrease in CD3+CD8+ cell numbers and facilitated complete recovery of granzyme B+ cell percentages. IL-15 completely reversed the asbestos-induced decrease in percentage of granzyme B+ cells in both non-proliferating CFSE-positive and proliferating CFSE-negative CD8+ cells. The asbestos-induced decrease in the percentage of CD25+ and CD45RO+ cells in CD8+ lymphocytes was not reversed by IL-15. CONCLUSION: These findings indicate that CTLs induced upon exposure to asbestos possess dysfunctional machinery that can be partly compensated by IL-15 supplementation, and that IL-15 is more effective in the recovery of proliferation and granzyme B levels from asbestos-induced suppression of CTL induction compared with IL-2.

Ingredients such as trehalose and hesperidin taken as supplements or foods reverse alterations in human T cells, reducing asbestos exposure-induced antitumor immunity.

Exposure of human immune cells to asbestos causes a reduction in antitumor immunity. The present study aimed to investigate the recovery of reduced antitumor immunity by several ingredients taken as supplements or foods, including trehalose (Treh) and glycosylated hesperidin (gHesp). Peripheral blood CD4+ cells were stimulated with IL­2, anti­CD3 and anti­CD28 antibodies for 3 days, followed by further stimulation with IL­2 for 7 days. Subsequently, cells were stimulated with IL­2 for an additional 28 days. During the 28 days, cells were cultured in the absence or presence of 50 µg/ml chrysotile asbestos fibers. In addition, cells were treated with 10 mM Treh or 10 µM gHesp. Following culture for 28 days, reverse transcription­quantitative PCR was performed to assess the expression levels of transcription factors, cytokines and specific genes, including matrix metalloproteinase­7 (MMP­7), nicotinamide nucleotide transhydrogenase (NNT) and C­X­C motif chemokine receptor 3, in unstimulated cells (fresh) and cells stimulated with PMA and ionomycin (stimuli). The results demonstrated that compared with the control group, chrysotile­exposure induced alterations in MMP­7, NNT and IL­17A expression levels were not observed in the 'Treh' and 'gHesp' groups in stimulated cells. The results suggested that Treh and gHesp may reverse asbestos exposure­induced reduced antitumor immunity in T helper cells. However, further investigation is required to confirm the efficacy of future trials involving the use of these compounds with high­risk human populations exposed to asbestos, such as workers involved in asbestos­handling activities.

Increased production of matrix metalloproteinase-7 (MMP-7) by asbestos exposure enhances tissue migration of human regulatory T-like cells.

The effects of asbestos on immunocompetent cells have been investigated. In particular, attention was paid to regulatory T cell function, which was observed using the HTLV-1 immortalized human polyclonal T cell line MT-2. Exposure to asbestos (approximately more than 25 µg/mL for 1-3 day) induced apoptosis, and we observed an increase in regulatory T cell function and acceleration of the cell cycle with continuous exposure to low concentrations of asbestos (5-10 µg/mL for more than eight months). Furthermore, cDNA microarray analysis in this study revealed that expression of matrix metalloproteinase-7 (MMP-7) was markedly higher in exposed sublines compared to original MT-2 cells. It was determined that MMP-7 had no effect on Treg function, as determined by examination of sublines and by addition of recombinant MMP-7 and neutralizing antibodies or inhibitors of MMP-7. However, when examining melting of the extracellular matrix (an MMP-7-mediated event) or the extent to which the MT-2 parent strain or long-term exposed subline cells pass through a fibronectin-coated filter, more filter passes were observed for the subline. These results suggest that the effect of asbestos fibers on Treg cells results in excessive migration of the tumor microenvironment through hypersecretion of MMP-7 together with an increase in suppressive function and enhancement of cell cycle progression. Therefore, one possible way to prevent the development of asbestos-induced cancer is to reduce the function (including MMP-7 production) or amount of Treg cells by physiologically active substances or food ingredients. Alternatively, it may be possible to invoke immune checkpoint treatments when carcinogenesis occurs.

Effect of asbestos exposure on differentiation and function of cytotoxic T lymphocytes.

Asbestos exposure is known to cause malignant mesothelioma, which is associated with poor prognosis. We focused on and examined the effect of asbestos exposure on the differentiation and function of cytotoxic T lymphocytes (CTLs). CTLs have the ability to specifically attack tumor cells after being differentiated from naïve CD8+ T cells following antigen stimulation. Exposure to chrysotile B asbestos suppressed the differentiation of CTLs during the mixed lymphocyte reaction (MLR) and was associated with a decrease in proliferation of CD8+ T cells. Additionally, in an effort to investigate the mechanism associated with suppressed CTL differentiation upon exposure to asbestos, we focused on IL-2, a cytokine involved in T cell proliferation. Our findings indicated that insufficient levels of IL-2 are not the main cause for the suppressed induction of CTLs by asbestos exposure, although they suggest potential improvement in the suppressed CTL function. Furthermore, the functional properties of peripheral blood CD8+ lymphocytes from asbestos-exposed individuals with pleural plaque (PP) and patients with malignant mesothelioma (MM) were examined. MM patients showed lower perforin levels in CD8+ lymphocytes following stimulation compared with PP-positive individuals. The production capacity of IFN-γ in the MM group tended to be lower compared with healthy volunteers or PP-positive individuals. In an effort to determine whether chronic and direct asbestos exposure affected the function of CD8+ T cells, cultured human CD8+ T cells were employed as an in vitro model and subjected to long-term exposure to chrysotile (CH) asbestos. This resulted in decreased levels of intracellular perforin and secreted IFN-γ. Those findings underlie the possibility that impaired CD8+ lymphocyte function is caused by asbestos exposure, which fail to suppress the development of MM. Our studies therefore reveal novel effects of asbestos exposure on CTLs, which might contribute towards the development and implementation of an effective strategy for the prevention and cure of malignant mesothelioma.

The Effects of Asbestos Fibers on Human T Cells.

Asbestos exposure causes malignant tumors such as lung cancer and malignant mesothelioma. The effects of asbestos fibers on immunocompetent cells, however, have not been well studied. Asbestos physically comprises a fibrous substance, which differs from silica particles which are a particulate substance, although chemically it is a mineral silicate. Since silicosis patients previously exposed to silica particles often suffer from lung and autoimmune diseases, it is clear that silica exposure impairs immune tolerance. Similarly, asbestos may alter the immune system in asbestos-exposed individuals. Given that malignant tumors can result following exposure to asbestos, the attenuation of anti-tumor immunity in cases of asbestos exposure is an important area of investigation. We observed the effect of asbestos fibers on T lymphocytes, such as CD8+ cytotoxic T lymphocytes (CTLs), CD4+ helper T (Th), and regulatory T (Treg) cells, and showed that anti-tumor immunity was attenuated, as demonstrated in a system that stimulates fresh cells isolated from peripheral blood in vitro and a system that is continuously exposed to a cell line. In this manuscript, we introduce the experiments and results of studies on CTLs, as well as Th and Treg cells, and discuss how future changes in immunocompetent cells induced by asbestos fibers can be clinically linked.

Structure-based design of gRNA for Cas13.

Cas13 endonuclease activity depends on the RNA local secondary structure with strong preference for single-stranded (SS) regions. Hence, it becomes indispensable to identify the SS regions for effective Cas13 mediated RNA knockdown. We herein present rational gRNA design by integrating experimental structure-seq data and predicted structural models. Utilizing structure-seq data for XIST transcript, we observed that gRNAs targeting the SS regions significantly induce transcript knockdown and cleavage than those targeting double-stranded (DS) regions. Further, we identified the "central seed region" in the gRNA that upon targeting the SS regions efficiently facilitates Cas13 mediated cleavage. In our following pursuits, we considered the scenario wherein experimental structure-seq data is not available, hence we used SS18-SSX2 fusion transcript indicated in synovial sarcomas and computationally predicted its structure. We observed that gRNAs targeting the SS regions predicted from the structure, efficiently induced necrosis compared to gRNAs that target the DS regions. In conclusion, for the effective RNA knockdown, the Cas13 mediated targeting strategy presented herein emphasizes the designing of gRNAs specifically targeting SS regions by utilizing structural information. Further, this strategy, in turn, can be anticipated to narrow the search space for gRNA design (by exclusively targeting SS regions) especially when lncRNAs are the targets.

Enhanced expression of nicotinamide nucleotide transhydrogenase (NNT) and its role in a human T cell line continuously exposed to asbestos.

The effects of asbestos fibers on human immune cells have not been well documented. We have developed a continuously exposed cell line model using the human T-lymphotropic virus 1 (HTLV-1)-immortalized human T cell line MT-2. Sublines continuously exposed to chrysotile (CH) or crocidolite (CR) showed acquired resistance to asbestos-induced apoptosis following transient and high-dose re-exposure with fibers. These sublines in addition to other immune cells such as natural killer cells or cytotoxic T lymphocytes exposed to asbestos showed a reduction in anti-tumor immunity. In this study, the expression of genes and molecules related to antioxidative stress was examined. Furthermore, complexes related to oxidative phosphorylation were investigated since the production of reactive oxygen species (ROS) is important when considering the effects of asbestos in carcinogenesis and the mechanisms involved in resistance to asbestos-induced apoptosis. In sublines continuously exposed to CH or CR, the expression of thioredoxin decreased. Interestingly, nicotinamide nucleotide transhydrogenase (NNT) expression was markedly enhanced. Thus, knockdown of NNT was then performed. Although the knockdown clones did not show any changes in proliferation or occurrence of apoptosis, these clones showed recovery of ROS production with returning NADPH/NADP+ ratio that increased with decreased production of ROS in continuously exposed sublines. These results indicated that NNT is a key factor in preventing ROS-induced cytotoxicity in T cells continuously exposed to asbestos. Considering that these sublines showed a reduction in anti-tumor immunity, modification of NNT may contribute to recovery of the anti-tumor effects in asbestos-exposed T cells.

Decrease in Intracellular Perforin Levels and IFN-γ Production in Human CD8+ T Cell Line following Long-Term Exposure to Asbestos Fibers.

Although the tumorigenicity of asbestos, which is thought to cause mesothelioma, has been clarified, its effect on antitumor immunity requires further investigation. We previously reported a decrease in the percentage of perforin+ cells of stimulated CD8+ lymphocytes derived from patients with malignant mesothelioma. Therefore, we examined the effects of long-term exposure to asbestos on CD8+ T cell functions by comparing long-term cultures of the human CD8+ T cell line EBT-8 with and without exposure to chrysotile (CH) asbestos as an in vitro model. Exposure to CH asbestos at 5 µg/ml or 30 µg/ml did not result in a decrease in intracellular granzyme B in EBT-8 cells. In contrast, the percentage of perforin+ cells decreased at both doses of CH exposure. CH exposure at 30 µg/ml did not suppress degranulation following stimulation with antibodies to CD3. Secreted production of IFN-γ stimulated via CD3 decreased by CH exposure at 30 µg/ml, although the percentage of IFN-γ + cells induced by PMA/ionomycin did not decrease. These results indicate that long-term exposure to asbestos can potentially suppress perforin levels and the production of IFN-γ in human CD8+ T cells.

Aberrant expression of FoxP3 in a human T cell line possessing regulatory T cell­like function and exposed continuously to asbestos fibers.

Prompted by the known carcinogenic activity of asbestos, our investigations revealed that asbestos causes a reduction in antitumor immunity. One mechanism involves the enhancement of regulatory T (Treg) cell function and volume assayed using MT­2 original cells (Org), an HTLV­1 immortalized human T cell line which possesses Treg­like function. Continuous and relatively low­dose exposure of MT­2 to asbestos fibers yielded sublines resistant to asbestos­induced apoptosis and enhanced Treg function via cell­cell contact mechanisms and increased the production of soluble factors such as interleukin (IL)­10 and transforming growth factor (TGF)­ß. Additionally, cell cycle progression was accelerated in these sublines. Subsequently, the status of the Treg­specific transcription factor FoxP3 was examined. Unexpectedly, FoxP3 mRNA levels decreased in the sublines, although significant changes in protein expression were absent. Methylation analysis of CpG sites located in the promoter region of FoxP3 in original MT­2 cells and sublines showed almost complete methylation in Org and slight hypomethylation in the sublines. Although treatment with the demethylating agent 5­aza­deoxycytidine tended to upregulate FoxP3 expression, the methylation status did not match the mRNA expression and enhanced function. Additionally, the expression of other transcription factors related to Treg did not differ between Org and subline CB1. Collectively, aberrant expression and methylation patterns of FoxP3 were detected in human T cells continuously exposed to asbestos, although cell function was enhanced by asbestos exposure. Future analyses to identify factors responsible for Treg functional enhancements induced by asbestos, such as the investigation of surface molecules, are needed for the development of strategies to prevent the occurrence of asbestos­induced cancers.

Cytokine Profile and Immunoglobulin E-mediated Serological Food Hypersensitivity in Patients With Irritable Bowel Syndrome With Diarrhea.

BACKGROUND/AIMS: Food interaction, including food hypersensitivity, plays a key role in the pathogenesis of irritable bowel syndrome with diarrhea (IBS-D). Since only a few studies have been reported about the relationship between food hypersensitivity and IBS-D, we elucidate the prevalence of serological food hypersensitivity in patients with IBS-D and the characteristics of gastrointestinal symptoms and serum cytokine profiles in patients with IBS-D and serological food hypersensitivity. METHODS: Immunoglobulin E (Ig E)-mediated serological food hypersensitivity and serum cytokine levels were evaluated using the multiple allergen simultaneous test evaluating food allergen-specific serum IgE and Luminex Milliplex Panel containing multiple fluorescence-labeled beads. Class 2 or above was considered as IgE-mediated food hypersensitivity positive. The gastrointestinal symptom rating scale was used to evaluate symptoms. RESULTS: We enrolled 92 subjects, including 60 with IBS-D and 32 healthy controls. The percentages of patients with IgE-mediated serological food hypersensitivity were not significantly different between the groups (controls = 28.1% and IBS-D = 33.3%). Serum IL-1ß, IL-6, IL-8, macrophage inflammatory protein-1alpha, and TNF-α levels were higher in patients with IBS-D than in controls. Serum concentration of TNF-α (43.4 vs 21.8 pg/mL, P = 0.009) was higher in patients with IBS-D without IgE-mediated serological food hypersensitivity than those with food hypersensitivity. CONCLUSIONS: One-third of Japanese patients with IBS-D showed IgE-mediated serological food hypersensitivity. The serum cytokine profile differed and was characterized by lower inflammatory cytokine levels in IBS-D with IgE-mediated serological food hypersensitivity. Serological test regarding IgE-mediated food hypersensitivity can detect a certain cluster of IBS-D.

Inflammatory Alteration of Human T Cells Exposed Continuously to Asbestos.

Asbestos is a known carcinogen and exposure can lead to lung cancer and malignant mesothelioma. To examine the effects of asbestos fibers on human immune cells, the human T cell leukemia/lymphoma virus (HTLV)-1 immortalized human T cell line MT-2 was employed. Following continuous exposure to asbestos fibers for more than eight months, MT-2 sublines showed acquisition of resistance to asbestos-induced apoptosis with decreased death signals and increased surviving signals. These sublines showed various characteristics that suggested a reduction in anti-tumor immunity. On the other hand, inflammatory changes such as expression of MMP7, CXCR5, CXCL13 and CD44 was found to be markedly higher in sublines continuously exposed to asbestos compared with original MT-2 cells. All of these molecules contribute to lung inflammation, T and B cell interactions and connections between mesothelial cells and T cells. Thus, further investigation focusing on these molecules may shed light on the role of chronic inflammation caused by asbestos exposure and the occurrence of malignant mesothelioma. Finally, regarding peripheral T cells from healthy donors (HD) and asbestos-exposed patients with pleural plaque (PP) or malignant pleural mesothelioma (MPM), following stimulation of CD4+ T cells, T cells from MPM patients showed reduced potential of interferon (IFN)-γ expression. Moreover, levels of interleukin (IL)-6, one of the most important cytokines in chronic inflammation, in cultured supernatants were higher in PP and MPM patients compared with HD. Overall, asbestos-induced chronic inflammation in the lung as well as the pleural cavity may facilitate the onset of asbestos-induced cancers due to alterations in the interactions among fibers, immune cells such as T and B cells and macrophages, and mesothelial and lung epithelial cells. Further investigations regarding chronic inflammation caused by asbestos fibers may assist in identifying molecular targets for preventive and therapeutic strategies related to the effects of asbestos exposure.

Search for biomarkers of asbestos exposure and asbestos-induced cancers in investigations of the immunological effects of asbestos.

The immunological effects of asbestos exposure on various lymphocytes such as the regulatory T cell (Treg), responder CD4+ T helper cell (Tresp), CD8+ cytotoxic T lymphocytes (CTL), and natural killer (NK) cells were investigated. Results show that asbestos exposure impairs antitumor immunity through enhancement of regulatory T cell function and volume, reduction of CXCR3 chemokine receptor in responder CD4+ T helper cells, and impairment of the killing activities of CD8+ cytotoxic T lymphocytes (CTL) and NK cells. These findings were used to explore biological markers associated with asbestos exposure and asbestos-induced cancers and suggested the usefulness of serum/plasma IL-10 and TGF-ß, surface CXCR3 expression in Tresp, the secreting potential of IFN-γ in Tresp, intracellular perforin level in CTL, and surface expression NKp46 in NK cells. Although other unexplored cytokines in serum/plasma and molecules in these immunological cells, including Th17, should be investigated by experimental procedures in addition to a comprehensive analysis of screening methods, biomarkers based on immunological alterations may be helpful in clinical situations to screen the high-risk population exposed to asbestos and susceptible to asbestos-related cancers such as mesothelioma.

Induction of IL-17 production from human peripheral blood CD4+ cells by asbestos exposure.

We have previously reported that chronic, recurrent and low-dose exposure to asbestos fibers causes a reduction in antitumor immunity. Investigation of natural killer (NK) cells using an in vitro cell line model and comprising in vitro activation using freshly isolated NK cells co-cultured with chrysotile fibers, as well as NK cells derived from asbestos-exposed patients with pleural plaque (PP) or malignant mesothelioma (MM), revealed decreased expression of NK cell activating receptors such as NKG2D, 2B4 and NKp46. An in vitro differentiation and clonal expansion model for CD8+ cytotoxic T lymphocytes (CTLs) showed reduced cytotoxicity with decreased levels of cytotoxic molecules such as granzyme B and perforin, as well as suppressed proliferation of CTLs. Additionally, analysis of T helper cells showed that surface CXCR3, chemokine receptor, and the productive potential of interferon (IFN)γ were reduced following asbestos exposure in an in vitro cell line model and in peripheral CD4+ cells of asbestos-exposed patients. Moreover, experiments revealed that asbestos exposure enhanced regulatory T cell (Treg) function. This study also focused on CXCR3 expression and the Th-17 cell fraction. Following activation with T-cell receptor and co-culture with various concentrations of chrysotile fibers using freshly isolated CD4+ surface CXCR3 positive and negative fractions, the intracellular expression of CXCR3, IFNγ and IL-17 remained unchanged when co-cultured with chrysotile. However, subsequent re-stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin resulted in enhanced IL-17 production and expression, particularly in CD4+ surface CXCR3 positive cells. These results indicated that the balance and polarization between Treg and Th-17 fractions play an important role with respect to the immunological effects of asbestos and the associated reduction in antitumor immunity.

Accelerated cell cycle progression of human regulatory T cell-like cell line caused by continuous exposure to asbestos fibers.

Asbestos exposure causes malignant tumors such as lung cancer and malignant mesothelioma. Based on our hypothesis in which continuous exposure to asbestos of immune cells cause reduction of antitumor immunity, the decrease of natural killer cell killing activity with reduction of NKp46 activating receptor expression, inhibition of cytotoxic T cell clonal expansion, reduced CXCR3 chemokine receptor expression and production of interferon-γ production in CD4+ T cells were reported using cell line models, freshly isolated peripheral blood immune cells from health donors as well as asbestos exposed patients such as pleural plaque and mesothelioma. In addition to these findings, regulatory T cells (Treg) showed enhanced function through cell-cell contact and increased secretion of typical soluble factors, interleukin (IL)-10 and transforming growth factor (TGF)-ß, in a cell line model using the MT-2 human polyclonal T cells and its sublines exposed continuously to asbestos fibers. Since these sublines showed a remarkable reduction of FoxO1 transcription factor, which regulates various cell cycle regulators in asbestos-exposed sublines, the cell cycle progression in these sublines was examined and compared with that of the original MT-2 cells. Results showed that cyclin D1 expression was markedly enhanced, and various cyclin-dependent kinase-inhibitors were reduced with increased S phases in the sublines. Furthermore, the increase of cyclin D1 expression was regulated by FoxO1. The overall findings indicate that antitumor immunity in asbestos-exposed individuals may be reduced in Treg through changes in the function and volume of Treg.

The Suppressed Induction of Human Mature Cytotoxic T Lymphocytes Caused by Asbestos Is Not due to Interleukin-2 Insufficiency.

We previously reported that exposure to chrysotile B (CB) asbestos suppressed the induction of mature cytotoxic T lymphocytes (CTLs) during mixed lymphocyte reaction assays (MLRs) with a decrease in the proliferation of immature CTLs. However, the mechanism responsible for the effect of asbestos fibers on the differentiation of CTLs remains unclear. Since interleukin-2 (IL-2) is a regulator of T lymphocyte proliferation, we examined the effect of IL-2 addition on suppressed CTL differentiation in CB-exposed cultures using flow cytometry (FCM). When IL-2 was added at 1 ng/mL on the second day of MLRs, the asbestos-caused decreases in the proliferation and percentages of CD25+ and CD45RO+ cells in CD8+ lymphocytes were not recovered by IL-2 addition, although the decrease in percentage of granzyme B+ cells was partially recovered. CD8+ lymphocytes from the IL-2-treated culture with asbestos showed the same degree of cytotoxicity as those in cultures without IL-2 or asbestos. These findings indicate that IL-2 insufficiency is not the main cause for the suppressed induction of CTLs by asbestos exposure, although they suggest a potential for the improvement of such suppressed CTL functions. Secretory factors other than IL-2 in addition to membrane-bound stimulatory molecules may play a role in asbestos-caused suppressed CTL differentiation.

Biological Effects of Cloth Containing Specific Ore Powder in Patients with Pollen Allergy.

OBJECTIVE: The custom-homebuilding company, Cosmic Garden Co. Ltd., located in Okayama City, Japan was established in 1997 and uses specific natural ore powder (SNOP) in wall materials and surveys customers in order to improve allergic symptoms. METHODS: To investigate the biological effects of SNOP, patients with a pollen allergy were recruited to stay in a room surrounded by cloth containing SNOP (CCSNOP), and their symptoms and various biological parameters were compared with those of individuals staying in a room surrounded by control non-woven cloth (NWC). Each stay lasted 60 min. Before and immediately after the stay, a questionnaire regarding allergic symptoms, as well as POMS (Profile of Mood Status) and blood sampling, was performed. Post-stay minus pre-stay values were calculated and compared between CCSNOP and NWC groups. RESULTS: Results indicated that some symptoms, such as nasal obstruction and lacrimation, improved, and POMS evaluation showed that patients were calmer following a stay in CCSNOP. Relative eosinophils, non-specific Ig E, epidermal growth factor, monocyte chemotactic protein-1, and tumor necrosis factor-α increased following a stay in CCSNOP. CONCLUSION: This ore powder improved allergic symptoms, and long-term monitoring involving 1 to 2 months may be necessary to fully explore the biological and physical effects of SNOP on allergic patients.

FoxO1 regulates apoptosis induced by asbestos in the MT-2 human T-cell line.

Asbestos is known to cause malignant mesothelioma and lung cancer. Recent studies implicate tumor immunity in the development of various tumors, including malignant mesothelioma. In order to establish an in vitro T-cell model to clarify the effects of long-term exposure of asbestos on tumor immunity, in this study, human T-cell line MT-2 cells were cultured with asbestos for longer than 8 months and the resultant cells (MT-2Rst) were assessed for the expression of forkhead transcription factor FoxO1. Gene expression analysis revealed that the amount of FoxO1 mRNA decreased after long-term exposure of the MT-2 cells to asbestos. In accordance with this reduction in FoxO1, pro-apoptotic Foxo1 target genes Puma, Fas ligand and Bim were also seen to be down-regulated in MT-2Rst cells. Furthermore, shRNA-mediated knock-down of FoxO1 reduced the number of apoptotic parental MT-2 cells after treatment with asbestos. On the other hand, over-expression of FoxO1 did not affect asbestos-induced apoptosis in MT-2Rst cells. These results suggested that FoxO1 played an important role in regulating asbestos-induced apoptosis and confirmed the presence of multiple pathways regulating resistance to asbestos in MT-2Rst cells.

The proliferative effects of asbestos-exposed peripheral blood mononuclear cells on mesothelial cells.

Malignant mesothelioma (MM) is thought to arise from the direct effect of asbestos on mesothelial cells. However, MM takes a long time to develop following exposure to asbestos, which suggests that the effects of asbestos are complex. The present study examined the effects of asbestos exposure on the cell growth of MeT-5A human mesothelial cells via cytokines produced by immune cells. Peripheral blood mononuclear cells (PBMCs) were stimulated with antibodies against cluster of differentiation (CD)3 and CD28 upon exposure to the asbestos chrysotile A (CA) or crocidolite (CR); the growth of MeT-5A cells in media supplemented with PBMC culture supernatants was subsequently examined. MeT-5A cells exhibited an increase in proliferation when grown in supernatant from the 7-day PBMC culture exposed to CA or CR. Analysis of cytokine production demonstrated increased levels of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-1α, IL-1ß, IL-3, IL-5, IL-13 and IL-17A in supernatants. Individual administration of these cytokines, excluding G-CSF and GM-CSF, led to an increase in cell growth of MeT-5A, whereas this effect was not observed following the combined administration of these cytokines. The results indicate that cytokines secreted by immune cells upon exposure to asbestos cause an increase in the growth activity of mesothelial cells, suggesting that alterations in the production of cytokines by immune cells may contribute to tumorigenesis in individuals exposed to asbestos.

Environmental factors and human health: fibrous and particulate substance-induced immunological disorders and construction of a health-promoting living environment.

Among the various scientific fields covered in the area of hygiene such as environmental medicine, epidemiology, public health and preventive medicine, we are investigating the immunological effects of fibrous and particulate substances in the environment and work surroundings, such as asbestos fibers and silica particles. In addition to these studies, we have attempted to construct health-promoting living conditions. Thus, in this review we will summarize our investigations regarding the (1) immunological effects of asbestos fibers, (2) immunological effects of silica particles, and (3) construction of a health-promoting living environment. This review article summarizes the 2014 Japanese Society for Hygiene (JSH) Award Lecture of the 85th Annual Meeting of the JSH entitled "Environmental health effects: immunological effects of fibrous and particulate matter and establishment of health-promoting environments" presented by the first author of this manuscript, Prof. Otsuki, Department of Hygiene, Kawasaki Medical School, Kurashiki, Japan, the recipient of the 2014 JSH award. The results of our experiments can be summarized as follows: (1) asbestos fibers reduce anti-tumor immunity, (2) silica particles chronically activate responder and regulatory T cells causing an unbalance of these two populations of T helper cells, which may contribute to the development of autoimmune disorders frequently complicating silicosis, and (3) living conditions to enhance natural killer cell activity were developed, which may promote the prevention of cancers and diminish symptoms of virus infections.