Dysregulation of cytokine response in Canadian First Nations communities: is there an association with persistent organic pollutant levels?

In vitro and animal studies report that some persistent organic pollutants (POPs) trigger the secretion of proinflammatory cytokines. Whether POP exposure is associated with a dysregulation of cytokine response remains to be investigated in humans. We studied the strength of association between plasma POP levels and circulating cytokines as immune activation markers. Plasma levels of fourteen POPs and thirteen cytokines were measured in 39 Caucasians from a comparator sample in Québec City (Canada) and 72 First Nations individuals from two northern communities of Ontario (Canada). Caucasians showed significantly higher levels of organochlorine insecticides (ß-HCH, p,p'-DDE and HCB) compared to First Nations. Conversely, First Nations showed higher levels of Mirex, Aroclor 1260, PCB 153, PCB 170, PCB 180 and PCB 187 compared to Caucasians. While there was no difference in cytokine levels of IL-4, IL-6, IL-10 and IL-22 between groups, First Nations had significantly greater average levels of IFNγ, IL-1ß, IL-2, IL-5, IL-8, IL-12p70, IL-17A, TNFα and TNFß levels compared to Caucasians. Among candidate predictor variables (age, body mass index, insulin resistance and POP levels), high levels of PCBs were the only predictor accounting for a small but significant effect of observed variance (∼7%) in cytokine levels. Overall, a weak but significant association is detected between persistent organochlorine pollutant exposure and elevated cytokine levels. This finding augments the already existing information that environmental pollution is related to inflammation, a common feature of several metabolic disorders that are known to be especially prevalent in Canada's remote First Nations communities.

Obesity and type 2 diabetes prevalence in adults from two remote first nations communities in northwestern ontario, Canada.

Objective. To assess the prevalence rates of obesity and type 2 diabetes in adults from two First Nations communities in northwestern Ontario, Canada. Methods. Body weight, height, and waist circumference as well as fasting and postprandial glucose levels following an oral glucose tolerance test were measured in 31 men and 41 women. Results. The mean age of the sample was 43 ± 13 y. The prevalence of obesity was 65.3% and was comparable between men and women. 90.3% of the individuals presented waist circumference levels greater than the thresholds associated with an increased risk of developing health problems. 26 of the 72 individuals (36.1%) were found to be type 2 diabetic. The prevalence of diabetes was not different between men and women. Conclusion. Using objective measurements, this study confirms that First Nations adults from remote communities of Canada continue to experience a disproportionately higher prevalence of obesity and type 2 diabetes than nonaboriginal Canadians.