Monohydroxylated fatty acid content in peripheral blood mononuclear cells and immune status of people at long times after the Chernobyl accident

RADIATION DAMAGE OF THE NERVOUS SYSTEM AND ENDOCANABINOIDS

The review analyzes the change of the existing paradigm of high radioresistance of the nervous system according tothe results of the study of neuropsychiatric disorders in in the aftermath of the Chornobyl accident in both earlyand remote post-accident period. The participation of the endocannabinoid system in ensuring homeostasis andpathology formation, potential possibilities of using cannabis drugs, agonists and antagonists of endocannabinoidreceptors for the treatment of early and long-term effects of radiation are considered.

Gene Expression and Cellular Markers of Occupational Radiation Exposure in Chernobyl Shelter Construction Workers

Low-dose radiation effects were studied in Ukrainian personnel of the Chernobyl exclusion zone. The aim of this study was to determine the influence of borderline exposure to annual professional limits and age on expression of molecular markers. Study groups included 300 radiation workers performing construction work on the New Safe Confinement (Arch) upon the Chernobyl "Shelter" [external dose, 26.1 ± 18.1 mSv; age, 43.1 ± 10.3 y overall and 48.7 ± 5.9 y for 69 control persons]. Methods included gene expression using RT-PCR, flow cytometry of lymphocyte antigens, gamma-H2AX, Cyclin D1 expression, and relative telomere length using flow-FISH. A statistically significant upregulation of VEGFA BAX, DDB2, NFKB1 was shown at doses below 35 mSv. In workers aged under 40 y with doses higher than 35 mSv, an upregulation of 16 genes was revealed-VEGFA, TERF2, TERF1, BIRC5, BAX, TP53, DDB2, CDKN1B, CDKN2A, NFKB2, MAPK14, TGFBR1, MKNK2, CDKN1A, NFKB1, TP53I3; and four genes were downregulated-MADD, FASL, CSF2, and TERT. In workers older than 40 y, 8 genes were upregulated and 12 were downregulated. All groups showed an increased and dose-dependent gamma-H2AX expression. Downregulation of CCND1 genes in older groups was accompanied by lower numbers of Cyclin D1 protein expression and lower CD3 and CD4 cell counts. Upregulation of CSF2 in those over 40 y old positively correlated with B-cell and NK-cell counts. A non-linear type of gene expression response was demonstrated: in doses over 35 mSv for those over 40 y, the increased expression of gamma-H2AX is associated with upregulation of cell survival positive regulators-BIRC5, BRCA1, DDB2, CCND1, TERT genes, and longer telomeres; the younger age group was characterized by TERF1 and TERF2 upregulation and telomere shortening.

Co-exposure to internal and external radiation alters cesium biokinetics and retention in mice

Exposures in post-accidental situations are complex and include both external exposure and internal contamination with several radionuclides. However, in vivo and in vitro studies generally use simplified exposures, while a recent study suggested that combined external irradiation and internal contamination may induce more severe biological effects compared to single exposures. In an attempt to test the hypothesis of potential non-additive effects of multiple radiological exposures, we used a mouse model of combined external x-ray irradiation at 1 and 5 Gy and internal contamination with injection of 20 KBq ¹³⁷Cs. The results showed differential kinetics of ¹³⁷Cs elimination in irradiated animals compared to sham-irradiated, ¹³⁷Cs injected animals. Moreover, changes in plasma potassium and in relative testis weight were observed 38 days after irradiation and injection in co-exposed animals compared to ¹³⁷Cs injection alone. These results demonstrate that an external exposure combined with an internal contamination may lead to unexpected changes in biokinetics of radionuclides and biological effects compared to single exposures.

Radiosensitivity of human prostate cancer cells can be modulated by inhibition of 12-lipoxygenase

Nearly 30% of prostate cancer (PCa) patients treated with potentially curative doses relapse at the sites of irradiation. How some tumor cells acquire radioresistance is poorly understood. The platelet-type 12-lipoxygenases (12-LOX)-mediated arachidonic acid metabolism is important in PCa progression. Here we show that 12-LOX confers radioresistance upon PCa cells. Treatment with 12-LOX inhibitors baicalein or BMD122 sensitizes PCa cells to radiation, without radiosensitizing normal cells. 12-LOX inhibitors and radiation, when combined, have super additive or synergistic inhibitory effects on the colony formation of both androgen-dependent LNCaP and androgen-independent PC-3 PCa cells. In vivo, the combination therapy significantly reduced tumor growth.

Influence on the mouse immune system of chronic ingestion of 137Cs

The aim of this work was to determine the possible occurrence of damage to the immune system during the course of chronic ingestion of (137)Cs. BALB/C mice were used, with (137)Cs intake via drinking water at a concentration of 20 kBq l(-1). Adults received (137)Cs before mating and offspring were sacrificed at various ages between birth and 20 weeks. Phenotypic analysis of circulating blood cells and thymocytes did not show any significant modification of immune cell populations in animals ingesting (137)Cs as compared with control animals, with the exception of a slight increase in Treg percentage at the age of 12 weeks. Functional tests, including proliferative response to mitogens such as phytohaemagglutinin, response to alloantigens in mixed lymphocyte reaction and immunoglobulin response to vaccine antigens such as tetanus toxin and keyhole limpet haemocyanin did not show any significant functional modification of the immune system in (137)Cs-ingesting animals as compared with control animals. Overall, our results suggest that chronic ingestion of a low concentration of (137)Cs in drinking water in the long term does not have any biologically relevant effect on the immune system.

Effect of cesium radioisotope on humoral immune status in Ukrainian children with clinical symptoms of irritable bowel syndrome related to Chernobyl disaster

The aim of this study is to determine humoral immune status in Ukrainian children with clinical symptoms of irritable bowel syndrome 23 years after the Chernobyl disaster.

METHOD AND MATERIAL

The test population consisted of 95 participants: 75 rural patients aged 4-18, who lived in a contaminated area exposed to natural environmental radiation (falling under three groups) and 20 healthy urban participants from Kiev aged 5-15 as a control group. Internal radiation activity has been measured by gamma-ray spectrometry. B-lymphocytes population was analyzed with monoclonal antibody against antigen CD22(+). Serum immunoglobulins were evaluated by enzyme-linked immunosorbent assay (ELISA) method. p < 0.05 was considered significant.

RESULT

The percentage of CD22(+) in study groups is increased significantly in comparison to control group at p < 0.05. Reduced serum immunoglobulins levels have developed in the majority of the participants.

CONCLUSION

Humoral immune status of study groups with clinical symptom of irritable bowel syndrome residing in a contaminated area has changed.

Affects of ionizing radiation on T-cell population lymphocyte: a risk factor of irritable bowel syndrome

Irritable bowel syndrome is observed mostly in Ukrainian children and may be related to adverse health effects as a result of the Chernobyl disaster. The aim of this study was to determine status of T-cell population lymphocytes in children with clinical symptom of irritable bowel syndrome. The test population consisted of 95 participants: 75 rural patients aged 4 to 18 who lived in a contaminated area exposed to natural environmental radiation with clinical symptom of irritable bowel syndrome (categorized in three groups) and 20 healthy urban participants from Kiev aged 5 to 15 as control group. Internal radiation activity has been measured by gamma-ray spectrometry. Peripheral blood leukocytes were analyzed for T-lymphocytes subset such as T-lymphocytes (CD3(+)), T-helper (CD4(+)) and T-cytotoxic (CD8(+)) and then CD4/CD8 ratio was calculated. Percentage of CD3(+) and CD4(+) in all study groups decreased significantly in comparison to control group (p < 0.001). Percentage of CD8(+) increased significantly in all study groups in comparison to control group (p < 0.05). The CD4/CD8 ratio decreased significantly all study groups in comparison to control group (p < 0.001). Cellular immune status of study groups that are residing in a contaminated area has changed. Our data have demonstrated that this change may be related to a higher incidence of children with irritable bowel syndrome.

Dietary fish oil and pectin enhance colonocyte apoptosis in part through suppression of PPARdelta/PGE2 and elevation of PGE3

We have shown that dietary fish oil and pectin (FP) protects against radiation-enhanced colon cancer by upregulating apoptosis in colonic mucosa. To investigate the mechanism of action, we provided rats (n = 40) with diets containing the combination of FP or corn oil and cellulose (CC) prior to exposure to 1 Gy, 1 GeV/nucleon Fe-ion. All rats were injected with a colon-specific carcinogen, azoxymethane (AOM; 15 mg/kg), 10 and 17 days after irradiation. Levels of colonocyte apoptosis, prostaglandin E(2) (PGE(2)), PGE(3), microsomal prostaglandin E synthase-2 (mPGES-2), total beta-catenin, nuclear beta-catenin staining (%) and peroxisome proliferator-activated receptor delta (PPARdelta) expression were quantified 31 weeks after the last AOM injection. FP induced a higher (P < 0.01) apoptotic index in both treatment groups, which was associated with suppression (P < 0.05) of antiapoptotic mediators in the cyclooxygenase (COX) pathway (mPGES-2 and PGE(2)) and the Wnt/beta-catenin pathway [total beta-catenin and nuclear beta-catenin staining (%); P < 0.01] compared with the CC diet. Downregulation of COX and Wnt/beta-catenin pathways was associated with a concurrent suppression (P < 0.05) of PPARdelta levels in FP-fed rats. In addition, colonic mucosa from FP animals contained (P < 0.05) a proapoptotic, eicosapentaenoic acid-derived COX metabolite, PGE(3). These results indicate that FP enhances colonocyte apoptosis in AOM-alone and irradiated AOM rats, in part through the suppression of PPARdelta and PGE(2) and elevation of PGE(3). These data suggest that the dietary FP combination may be used as a possible countermeasure to colon carcinogenesis, as apoptosis is enhanced even when colonocytes are exposed to radiation and/or an alkylating agent.

Whether ionizing radiation is a risk factor for schizophrenia spectrum disorders?

The neural diathesis-stressor hypothesis of schizophrenia, where neurobiological genetic predisposition to schizophrenia can be provoked by environmental stressors is considered as a model of the effects of exposure to ionizing radiation. Analysis of information from electronic databases (MEDLINE, PsycINFO, EMBASE, Current Contents, Elsevier BIOBASE) and hand-made search was carried out. There are comparable reports on increases in schizophrenia spectrum disorders following exposure to ionizing radiation as a result of atomic bombing, nuclear weapons testing, the Chernobyl accident, environmental contamination by radioactive waste, radiotherapy, and also in areas with high natural radioactive background. The results of experimental radioneurobiological studies support the hypothesis of schizophrenia as a neurodegenerative disease. Exposure to ionizing radiation causes brain damage with limbic (cortical-limbic) system dysfunction and impairment of informative processes at the molecular level that can trigger schizophrenia in predisposed individuals or cause schizophrenia-like disorders. It is supposed that ionizing radiation can be proposed as a risk factor for schizophrenia spectrum disorders. The hypothesis that ionizing radiation is a risk factor for schizophrenia spectrum disorders can be tested using data from the Chernobyl accident aftermath. Implementation of a study on schizophrenia spectrum disorders in Chernobyl accident victims is of significance for both clinical medicine and neuroscience.

Late effects of the Chernobyl radiation accident on T cell-mediated immunity in cleanup workers

The main goal of this investigation was to evaluate the abnormal T-cell immunity in cleanup workers who took part in the cleanup after the Chernobyl accident in 1986. Peripheral blood mononuclear cells (MNCs) of apparently healthy cleanup workers (n = 134) were used to analyze the phenotype and proliferative response to mitogens in vitro. Evaluation of the MNC phenotype of cleanup workers did not reveal a significant disturbance in the T-cell subpopulation content except for an increase in CD3+CD16+56+ (NKT) cells. Immunophenotyping of phytohemagglutinin (PHA)-activated MNCs demonstrated suppression of CD4+ T-cell propagation and augmentation of CD8+ T-cell propagation in vitro compared to control individuals. DNA synthesis in the MNCs of cleanup workers was markedly inhibited after activation for 3 days with suboptimal concentrations of PHA, pokeweed mitogen and PMA. In contrast to control individuals, the monocytes of cleanup workers were able to stimulate the proliferation of T cells from healthy individuals but inhibited the proliferation of T cells from cleanup workers. This study affords a better understanding of the response of MNCs to stimulation with suboptimal concentrations of PHA and provides an approach to a more accurate analysis of the immunological disorders found after exposure to radiation from Chernobyl-related activities.