[Show abstract][Hide abstract] ABSTRACT: Gastric cancer (GC) is one of the cancers that reveal increased risk of mortality and incidence in atomic bomb survivors. The incidence of gastric cancer in the Life Span Study cohort of the Radiation Effects Research Foundation (RERF) increased with radiation dose (gender-averaged excess relative risk per Gy = 0.28) and remains high more than 65 years after exposure. To assess a possible role of gene-environment interaction, we examined the dose response for gastric cancer incidence based on immunosuppression-related IL-10 genotype, in a cohort study with 200 cancer cases (93 intestinal, 96 diffuse and 11 other types) among 4,690 atomic bomb survivors participating in an immunological substudy. Using a single haplotype block composed of four haplotype-tagging SNPs (comprising the major haplotype allele IL-10-ATTA and the minor haplotype allele IL-10-GGCG, which are categorized by IL-10 polymorphisms at -819A>G and -592T>G, +1177T>C and +1589A>G), multiplicative and additive models for joint effects of radiation and this IL-10 haplotyping were examined. The IL-10 minor haplotype allele(s) was a risk factor for intestinal type gastric cancer but not for diffuse type gastric cancer. Radiation was not associated with intestinal type gastric cancer. In diffuse type gastric cancer, the haplotype-specific excess relative risk (ERR) for radiation was statistically significant only in the major homozygote category of IL-10 (ERR = 0.46/Gy, P = 0.037), whereas estimated ERR for radiation with the minor IL-10 homozygotes was close to 0 and nonsignificant. Thus, the minor IL-10 haplotype might act to reduce the radiation related risk of diffuse-type gastric cancer. The results suggest that this IL-10 haplotyping might be involved in development of radiation-associated gastric cancer of the diffuse type, and that IL-10 haplotypes may explain individual differences in the radiation-related risk of gastric cancer.
Radiation Research 06/2013; 180(1). DOI:10.1667/RR3183.1 · 2.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Past exposure to atomic bomb (A-bomb) radiation has exerted various long-lasting deleterious effects on the health of survivors. Some of these effects are seen even after >60 yr. In this study, we evaluated the subclinical inflammatory status of 442 A-bomb survivors, in terms of 8 inflammation-related cytokines or markers, comprised of plasma levels of reactive oxygen species (ROS), interleukin (IL)-6, tumor necrosis factor α (TNF-α), C-reactive protein (CRP), IL-4, IL-10, and immunoglobulins, and erythrocyte sedimentation rate (ESR). The effects of past radiation exposure and natural aging on these markers were individually assessed and compared. Next, to assess the biologically significant relationship between inflammation and radiation exposure or aging, which was masked by the interrelationship of those cytokines/markers, we used multivariate statistical analyses and evaluated the systemic markers of inflammation as scores being calculated by linear combinations of selected cytokines and markers. Our results indicate that a linear combination of ROS, IL-6, CRP, and ESR generated a score that was the most indicative of inflammation and revealed clear dependences on radiation dose and aging that were found to be statistically significant. The results suggest that collectively, radiation exposure, in conjunction with natural aging, may enhance the persistent inflammatory status of A-bomb survivors.-Hayashi, T., Morishita, Y., Khattree, R., Misumi, M., Sasaki, K., Hayashi, I., Yoshida, K., Kajimura, J., Kyoizumi, S., Imai, K., Kusunoki, Y., Nakachi, K. Evaluation of systemic markers of inflammation in atomic-bomb survivors with special reference to radiation and age effects.
The FASEB Journal 08/2012; 26(11). DOI:10.1096/fj.12-215228 · 5.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Since radiation exposure affects the immune system as well as risk of various cancers, we have commenced an “immunogenome” study to look at genetic susceptibility to radiation-associated cancers. HLA class I molecules are known to regulate various immune and inflammatory responses.
In this study, we examined effects of radiation exposure on individual susceptibility to gastric cancer based on HLA Class I (HLA-A, -B, -C) polymorphisms. This study comprised 150 gastric cancer patients and 300 controls. HLA genotype distribution among the controls not exposed to atomic-bomb radiation was almost identical to that in the general Japanese population.
Comparison between non-exposed gastric cancer patients and non-exposed controls showed no statistically significant relationship between gastric cancer risk and HLA-B or HLA-C genotypes. However, frequency of HLA-A*2601, one of the HLA-A genotypes, was significantly lower among cases (3.7%) than controls (18.3%), with P<0.007. Exposure to atomic radiation enhanced overall risk of gastric cancer, although this risk differed by HLA class I genotype. With regard to the atomic-radiation-exposed gastric cancer patients and exposed controls, frequency of HLA-A*2601 among the gastric cancer patients (average radiation dose: 0.8 Gy) (18.8%) was almost the same as frequency among the controls (15.8%). Risk elevation by radiation was most prominent in HLA-A*2601, compared with other genotypes.
These results suggest that HLA-A*2601 may be involved in decreased gastric cancer risk among non-exposed people and that, among those with the HLA-A*2601 allele, radiation exposure may increase gastric cancer risk. On the basis of this finding, we conducted further analysis of association between the HLA-A*2601 allele and plasma levels of various inflammatory markers along with analyses of pathological typing and H. pylori infection.
[Show abstract][Hide abstract] ABSTRACT: RERF epidemiology studies found that risks of certain cancers among atomic-bomb (A-bomb) survivors, including gastric cancer, increased with past exposure dose to atomic radiation, and that these risks remain high even today. RERF immunology studies implied that radiation exposure greatly affected host immune systems of A-bomb survivors, further providing for the possibility that altered immune response in this population, specifically inflammatory response and immunological host defense, might be involved in the development of various cancers. In fact, we have reported that the enhancement of persistent inflammation with increased age was further accelerated among people exposed to A-bomb radiation.
In this study, we examined relationship between gastric cancer risk and radiation dose based on 43 SNPs of inflammation-related genes (IL1B, IL6, IL8, IL10, BAT1, NFKBIL1, LTA, TNF, and LST1), in a case-control study of 238 cases and 1757 controls within a subcohort of the RERF Adult Health Study. We found statistically significant association between IL10, LTA, and TNF SNPs and risk of gastric cancer, but not between other SNPs and risk of gastric cancer. Three SNPs on the LTA-TNF loci were associated with elevated risk of gastric cancer. Additionally, our genome analysis identified a single haplotype block within the IL10 gene locus, which was indicated by four htSNPs (generating two major alleles, IL10-ATTA and IL10-GGCG). We found that risk of gastric cancer significantly varied by IL-10 haplotype in both non-exposed and exposed individuals, and that risk-enhancing effects of radiation were evident in all the haplotypes. Our findings offer further evidence that variation in the IL10 and TNF loci affects gastric cancer risk.
[Show abstract][Hide abstract] ABSTRACT: Even after more than 60 years have passed, exposure to atomic-bomb (A-bomb) radiation continues to have long-term health effects in survivors, whose risks of inflammation-related diseases increase with increasing radiation dose. It is known that persistent inflammation underlies several cancers through increased production of reactive oxygen species (ROS) and endogenous tumor promoters (e.g., TNF-α).In our previous study, plasma levels of inflammatory cytokines and biomarkers, IL-6, TNF-α, CRP, IFN-γ, Igs, and erythrocyte sedimentation rate (ESR), increased significantly with radiation dose. We have recently developed an automated plasma ROS assay system based on use of a clinical chemistry analyzer. In this study we investigated association between radiation dose, plasma ROS levels, and sub-clinical inflammatory status in A-bomb survivors in Hiroshima. Excluding patients with history of cancer, rheumatoid arthritis, chronic bronchitis, or myocardial infarction, we randomly selected 442 study subjects from the Adult Health Study population, consisting of A-bomb survivors and unexposed people. We observed statistically significant radiation-associated increase in plasma ROS levels. ROS levels were positively associated with the inflammatory biomarkers IL-6, TNF-α, CRP, and ESR (P<0.05). Since both radiation and aging were associated with increased levels of ROS and other inflammatory markers, we estimated the effect of radiation in terms of age acceleration. Judging from the level of ROS in the present results and the levels of inflammatory biomarkers in the previous results, exposure to 1 Gy was equivalent to an increase in age of about 9.3 years.It is evident that total ROS production increased with enhanced inflammatory status, suggesting a plausible mechanistic pathway between radiation-induced persistent inflammation and cancer.
[Show abstract][Hide abstract] ABSTRACT: To improve our understanding of ionizing radiation effects on immune cells, we investigated steps leading to radiation-induced cell death in MOLT-4, a thymus-derived human leukemia cell. After exposure of MOLT-4 cells to 4 Gy of X-rays, irradiated cells sequentially showed increase in intracellular reactive oxygen species (ROS), decrease in mitochondrial membrane potential, and eventually apoptotic cell death. In the presence of the caspase inhibitor z-VAD-fmk, irradiated cells exhibited necrotic characteristics such as mitochondrial swelling instead of apoptosis. ROS generation was not detected during this necrotic cell death process. These results indicate that radiation-induced apoptosis in MOLT-4 cells requires elevation of intracellular ROS as well as activation of a series of caspases, whereas the cryptic necrosis program--which is independent of intracellular ROS generation and caspase activation--is activated when the apoptosis pathway is blocked.
[Show abstract][Hide abstract] ABSTRACT: The derivatives of reactive oxygen metabolites (D-ROM) test has been developed to determine the amount of oxygen-centered free radicals in a blood sample as a marker of oxidative stress. This study aims to improve the D-ROM test and develop an automated assay system by use of a clinical chemistry analyzer. Five microliters of serum was added to 1 well of a 96-well microtiter plate for a total 240microl of reaction solution containing alkylamine and metals. This was followed by automatic mixing, incubation and measurement of reactive oxygen species (ROS) levels as a color development at 505nm using a spectrophotometer with catalytic capability for transition metals. This assay system was used to measure serum levels of ROS in cigarette smokers and never-smokers, by way of example. The levels of serum ROS determined by this system correlate with the amounts of free radicals and peroxides, which reacted with various molecules in the body and formed stable metabolites. This test can use frozen sera as well as fresh ones. The inter- and intra-deviation of this system was within 5% and showed consistent linearity in the range between 4 and 500mg/l of hydrogen peroxides. Serum ROS levels among smokers increased with the number of cigarettes smoked per day (36.5% increment per pack per day; P<0.0001). This assay system will be a simple, inexpensive, and reliable tool for assessing oxidative stress in human populations. Our preliminary results on cigarette smoking imply that this assay system has potential for application in various epidemiological and clinical settings.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 07/2007; 631(1):55-61. DOI:10.1016/j.mrgentox.2007.04.006 · 3.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have previously shown that natural cytotoxic activity of peripheral blood lymphocytes was inversely related to cancer development based on a prospective cohort study. The genetic fraction of cytotoxic activity needs to be clarified, identifying individuals immunogenetically susceptible to cancer. A case-control study within the cohort members was designed: 102 cancer cases with peripheral lymphocyte DNA available and three control groups, each of which consisted of 204 subjects with each tertile level of cytotoxic activity. We first compared two control groups with high and low cytotoxic activity in terms of the single nucleotide polymorphisms in the natural killer complex gene region on chromosome 12p, identifying the haplotype alleles that were associated with the activity. Next, cancer risks were assessed for these haplotypes. We found two haplotype blocks, each of which generated two major haplotype alleles: low-activity-related LNK1 (frequency 0.478 and 0.615 in groups with high and low activity, respectively; P < 0.00008) and high-activity-related HNK1 (0.480 and 0.348; P < 0.0001), LNK2 (0.711 and 0.821; P < 0.0002), and HNK2 (0.272 and 0.174; P < 0.0008). These NKG2D haplotype alleles showed a significant difference between cases (0.632 for LNK1 and 0.333 for HNK1) and controls (0.554 for LNK1 and 0.406 for HNK1). The haplotype HNK1/HNK1 revealed a decreased risk of cancer (odds ratio, 0.471; 95% confidence interval, 0.233-0.952) compared with LNK1/LNK1. Individuals who are genetically predisposed to have low or high natural cytotoxic activity can in part be determined by NKG2D haplotyping, which in turn reveals an increased or decreased risk of cancer development.
Cancer Research 01/2006; 66(1):563-70. DOI:10.1158/0008-5472.CAN-05-2776 · 9.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To investigate the sensitivity of human hematopoietic stem cell populations to radiation and its relevance to intracellular events, specifically alteration in cellular energy production systems, we examined the frequency of apoptotic cells, generation of superoxide anions (O*2-), and changes in cytosol pH in umbilical cord blood (UCB) CD34+/CD38-, CD34+/CD38+ and CD34-/CD38+ cells before and after 5Gy of X-irradiation. Human UCB mononucleated cells were used in this study. After X-irradiation and staining subgroups of the cells with fluorescence (FITC, PE, or CY)-labeled anti-CD34 and anti-CD38 antibodies, analyses were performed by FACScan using as stains 7-amino-actinomycin D (7-AAD) for the detection of apoptosis, and hydroethidine (HE) for the measurement of O*2- generation in the cells. For intracellular pH, image analysis was conducted using confocal laser microscopy after irradiation and staining with carboxy-SNAFR-1. The frequency of apoptotic cells, as determined by cell staining with 7-AAD, was highest in the irradiated CD34+/CD38- cell population, where the level of O*2- detected by the oxidation of HE was also most highly elevated. Intracellular pH measured with carboxy-SNARF-1-AM by image cytometer appeared to be lowest in the same irradiated CD34+/CD38- cell population, and this intracellular pH decreased as early as 4 h post-irradiation, virtually simultaneous with the significant elevation of O*2- generation. These results suggest that the CD34+/CD38- stem cell population is sensitive to radiation-induced apoptosis as well as production of intracellular O*2-, compare to more differentiated CD34+/CD38+ and CD34-/CD38+ cells and that its intracellular pH declines at an early phase in the apoptosis process.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 12/2004; 556(1-2):83-91. DOI:10.1016/j.mrfmmm.2004.07.002 · 3.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We examined radiation effects on the relationship between diabetes development and genetic background in atomic-bomb (A-bomb) survivors. Our main aim in this study was to shed light on the role of genetic background in diabetes onset among A-bomb survivors by studying possible relationships between human leukocyte antigen (HLA) genotypes and the diabetes in patients and controls. We examined the effects of different HLA haplotypes on type 2 diabetes development by determining the DQA1 and DRB1 alleles of Hiroshima A-bomb survivors (111 diabetic patients and 774 controls) using the polymerase chain reaction-sequence specific oligonucleotide probes (PCR-SSOP) method. We noted an increased risk of diabetes in the higher dose group among these patients (trend p = 0.001). The risk of the most heavily exposed group was significantly higher than that of the unexposed group or the low-dose group especially in survivors with the DQA1*03-DRB1*09 or DQA1*0401-DRB1*08 haplotypes (trend p = 0.002 or p = 0.05, respectively). By contrast, in people with other haplotypes, the risk did not increase significantly with increasing dose. These results suggest that individuals with specific HLA haplotypes may have an increased risk of diabetes with increased-dose categories.
Human Immunology 10/2003; 64(9):910-6. DOI:10.1016/S0198-8859(03)00157-5 · 2.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The well-documented increases in malignant tumours in the A-bomb survivors have recently been supplemented by reports that non-cancer diseases, including cardiovascular disease, may also have increased in incidence with increasing radiation dose. Given that low-level inflammatory responses are widely accepted as a significant risk factor for such diseases, we undertook a detailed investigation of the long-term effects of ionizing radiation on the levels of the inflammatory markers C-reactive protein (CRP) and interleukin 6 (IL-6) in A-bomb survivors.
Blood samples were taken from 453 participants in a long-term epidemiological cohort of A-bomb survivors. Plasma levels of CRP and IL-6 were measured using standard antibody-mediated procedures. Relationships between CRP or IL-6 levels and radiation dose were then investigated by multivariate regression analysis. Blood lymphocytes from each individual were used for immunophenotyping by flow cytometry with murine monoclonal antibodies to CD3, CD4 and CD8.
CRP levels were significantly increased by about 31% Gy(-1) of estimated A-bomb radiation (p=0.0001). Higher CRP levels also correlated with age, male gender, body mass index and a history of myocardial infarction. After adjustments for these factors, CRP levels still appeared to have increased significantly with increasing radiation dose (about 28% increase at 1Gy, p=0.0002). IL-6 levels also appeared to have increased with radiation dose by 9.3% at 1Gy (p=0.0003) and after multiple adjustments by 9.8% at 1Gy (p=0.0007). The elevated CRP and IL-6 levels were associated with decreases in the percentages of CD4(+) helper T-cells in peripheral blood lymphocyte populations.
Our results appear to indicate that exposure to A-bomb radiation has caused significant increases in inflammatory activity that are still demonstrable in the blood of A-bomb survivors and which may lead to increased risks of cardiovascular disease and other non-cancer diseases.
International Journal of Radiation Biology 03/2003; 79(2):129-36. DOI:10.1080/713865035 · 1.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Significant decreases in the fraction of lymphocytes that are CD4(+) and increases in serum levels of some classes of immunoglobulin have been reported to occur in atomic bomb (A-bomb) survivors and in victims of the Chernobyl nuclear plant accident. To investigate the long-term effects of nuclear radiation on cellular immunity in more detail, we used limiting dilution assays with peripheral blood mononuclear cell preparations to analyze the T-cell responses of 251 A-bomb survivors exposed to less than 0.005 Gy and 159 survivors exposed to more than 1.5 Gy. The percentages of CD2-positive cells that were capable of proliferating in response to phytohemagglutinin (PHA) in the presence of exogenous interleukin 2 (IL2) did not differ substantially between distally exposed and more heavily exposed survivors. The heavily exposed survivors appeared to possess fewer T cells that were capable of proliferating in response to concanavalin A (Con A) or of producing interleukin 2. Assuming that CD4 T cells were the ones primarily responsible for producing IL2 in response to Con A, we were able to estimate how many cells in any given CD4 T-cell population were actually producing IL2. The results indicated that peripheral blood samples from heavily exposed survivors contained significantly fewer IL2-producing CD4 T cells than did similar samples from distally exposed survivors, indicating that significant exposure to A-bomb radiation may have a long-lasting negative effect on the capacity of CD4 T-cell populations to produce IL2.
[Show abstract][Hide abstract] ABSTRACT: We have previously reported 2 cases of healthy men showing in vivo monoclonal expansion of mature CD4- CD8- alpha beta T cells. In the present study, an additional 3 adults were found to exhibit such an expansion, among a total 464 adult donors studied. These 5 individuals were otherwise physiologically normal, with no history of severe illness and autoimmune disease at the time of examination. To investigate the mechanisms of the clonal expansion, further characterization of the clonal cells was attempted. No apparent preference for usage of the T cell receptor beta chain variable region was observed in the clonal T cells. These clonal T cells showed lectin-dependent or redirected antibody-dependent cell-mediated cytotoxicities, whereas they could not lyse autologous lymphoblastoid cell lines. Failure of Fas antigen expression was not observed for any of these clones. These results suggest that clonal expansion of CD4- CD8- alpha beta T cells frequently occurs in the periphery without any T cell abnormalities.
European Journal of Immunology 11/1993; 23(11):2735-2739. DOI:10.1002/eji.1830231102 · 4.03 Impact Factor