Effects of Great Lakes fish consumption on the immune system of Sprague-Dawley rats investigated during a two-generation reproductive study

Identification of Sex-Specific Transcriptome Responses to Polychlorinated Biphenyls (PCBs)

PCBs are classified as xenoestrogens and carcinogens and their health risks may be sex-specific. To identify potential sex-specific responses to PCB-exposure we established gene expression profiles in a population study subdivided into females and males. Gene expression profiles were determined in a study population consisting of 512 subjects from the EnviroGenomarkers project, 217 subjects who developed lymphoma and 295 controls were selected in later life. We ran linear mixed models in order to find associations between gene expression and exposure to PCBs, while correcting for confounders, in particular distribution of white blood cells (WBC), as well as random effects. The analysis was subdivided according to sex and development of lymphoma in later life. The changes in gene expression as a result of exposure to the six studied PCB congeners were sex- and WBC type specific. The relatively large number of genes that are significantly associated with PCB-exposure in the female subpopulation already indicates different biological response mechanisms to PCBs between the two sexes. The interaction analysis between different PCBs and WBCs provides only a small overlap between sexes. In males, cancer-related pathways and in females immune system-related pathways are identified in association with PCBs and WBCs. Future lymphoma cases and controls for both sexes show different responses to the interaction of PCBs with WBCs, suggesting a role of the immune system in PCB-related cancer development.

The impact of self-hypnosis and Johrei on lymphocyte subpopulations at exam time: a controlled study

In a prospective randomised controlled trial, 48 students were randomly assigned to stress reduction training before exams with self-hypnosis, Johrei or a mock neurofeedback relaxation control. Peripheral blood lymphocyte subpopulations and self-reported stress (Perceived Stress Scale) were measured before training and 1-2 months later as exams approached. Absolute number and percentages of CD3(+)CD4(+) and CD3(+)CD8(+) T lymphocytes, CD3(-)CD56(+) Natural Killer cells (NK cells) and NK cell cytotoxic activity was measured from venous blood. Stressed participants showed small but significant declines in both CD3(-)CD56(+) NK cell percentages and NK cell cytotoxic activity levels while CD3(+)CD4(+) T cell percentages increased, changes supported by correlations with perceived stress. The effects of stress were moderated in those who learned Johrei at exam time; 11/12 showed increases in CD3(-)CD56(+) NK cell percentages with decreased percentages of CD3(+)CD4(+) T cells, effects not seen in the relaxation control group. Stress was also buffered in those who learned and practised self-hypnosis in whom CD3(-)CD56(+) NK cell and CD3(+)CD4(+) T cell levels were maintained, and whose CD3(+)CD8(+) T cell percentages, shown previously to decline with exams, increased. The results compliment beneficial effects on mood of self-hypnosis and Johrei. The results are in keeping with beneficial influences of self-hypnosis and provide the first evidence of the suggestive value of the Japanese Johrei procedure for stress reduction, which clearly warrants further investigation.

Immunosuppression in mice fed on diets containing beluga whale blubber from the St Lawrence estuary and the Arctic populations

In order to assess the immunotoxic potential of naturally relevant mixtures of PCBs and other organohalogens, C57Bl/6 mice were fed on diets in which lipids were replaced by blubber of beluga whales from the highly contaminated population of the Saint-Lawrence River, and the less contaminated population from the Arctic. Different ratios of blubber from both sources were mixed in order to allow a dose-response study. Mice were fed for a period of 90 days at the end of which their immunological status was monitored. For general parameters such as body weight, weight of the spleen and the thymus no significant effect of diets were observed. The immunological endpoints such as the blastic transformation of splenocytes and the spleen NK cell activity were not significantly affected by any of the diets compared to control diets. While the different cell subpopulations of peripheral blood and thymus were not affected by the diets, a significant decrease was noted in the CD8+ T cell population in the spleen of mice fed with most of the diets containing beluga blubber. Moreover, the ability of splenic cells to elicit humoral response against sheep red blood cells as well as the potential of peritoneal macrophages to perform phagocytosis were suppressed by all diets containing beluga blubbers. In summary, there was no differences between the groups fed with a blubber diet with low and high organochlorine contamination. However, a clear immunosuppression was demonstrated when these groups were compared to the group fed with beef oil. Despite the fact that we cannot exclude a possible contribution of the fatty acid composition of the beluga blubber to the immunosupression, these results suggest the sensitivity of mouse immune system towards organohalogens, and point out the toxic potential of contaminant mixtures as found in the less contaminated Arctic population.

A multigeneration study to ascertain the toxicological effects of Great Lakes salmon fed to rats: study overview and design

Fish from the Great Lakes can be contaminated with a plethora of industrial, agricultural, and environmental chemicals. These chemicals have been associated with reproductive and other toxicological effects in fish and fish-eating birds found in the Great Lakes basin. To obtain more insight into this association, several laboratory studies have been undertaken wherein fish have been incorporated into the experimental diets to determine the effect of their ingestion upon the test animals. In addition, several human epidemiological studies have found correlations between Great Lakes fish consumption and effects in neonates which have been attributed to polychlorinated biphenyls without any appreciable consideration as to what synergistic or antagonistic effects other chemicals or heavy metals may or may not have contributed to the observed findings. Herein is presented the design of a two-generation feeding-reproduction study that incorporated lyophilized chinook salmon (Oncorhynchus tsawytscha) fillets into the diets of Sprague-Dawley rats. The findings of this study will be presented in the sections which follow.

The health Canada Great Lakes multigeneration study--summary and regulatory considerations

The Health Canada Multigeneration Study was initiated to determine the consequences in rodents consuming diets containing Lake Ontario (LO) or Lake Huron (LH) chinook salmon over successive generations. Following lyophilization, the contaminant levels in the salmon used in the formulation of the diets for this study exceeded a number of tolerances or guidelines established for contaminants in commercial fish and seafood products (PCBs, dioxin, mirex, chlordanes, mercury). Consumption of the fish diets by rats of two consecutive generations resulted in a variety of effects that can be described as adaptive responses or of limited biological significance. The two exceptions to this were (1) the suggestion of modification of working and reference memory in males of the high-dose groups 20% fish diets, which may have been related to decreases noted in neurotransmitters in several brain regions in these rats; and (2) an effect on thymus weights noted in the high-dose first generation (F1) reversibility study animals and an overall effect on T-helper/inducer lymphocyte subset numbers in the second generation (F2) male rats fed the LH diets compared to the LO diets. Relatively minor effects were observed in the rats consuming the 5% fish diets from either Great Lakes location (LH-5, LH-5), although their fish intake was approximately 16-fold greater on a daily basis than the average angler consuming Great Lakes sport fish (compared to a 60-fold greater intake in the 20% diet groups: LH-20, LO-20). Based on these study results with rats it would appear that for the average consumer of Great Lakes sports fish, the risk presented by the complex mixture of contaminants in chinook salmon collected from these two locations in the Great Lakes basin could be considered minimal, especially if sport fish consumption advisories are followed.