A palaeopathological and immunogenetic assessment of archaeological Canadian Inuit populations

Abstract

For centuries there has been a disparity in the health of Canadian Aboriginal populations and the colonizers who came to inhabit their territories. In contemporary times, this disparity is translated into a number of growing health concerns that appear at higher rates in circumpolar populations than in many other Canadian communities. Tuberculosis rates in Arctic and circumpolar communities, particularly those with a high Inuit demographic, remain more than 20 times higher than in any other population demographic. Understanding the factors that contribute to the continued prevalence and high incidence of TB in the Arcticcompared to the remainder of Canadian populations demonstrate requires a longitudinal analysis of a number of factors related to overall health. This dissertation explores this disparity through the examination of the immunogenetics and palaeopathology of an archaeological Inuit population. This archaeological cohort was assessed using palaeopathological techniques of to establish the disease burden experienced by the Inuit in the pre-contact and early contact period. The palaeopathologicual inventory also established individuals with possible TB pathologies as candidates for further molecular analysis. Molecular analyses focused on the establishment of Inuit ancestry and the examination of the presence of four polymorphic sites in the promoter regions of IL-6, IL-10, TNFα and IFNγ. Polymorphisms for the Th2 cytokines IL-6 and IL-10 are associated with the down regulation of Th1 cytokines activated to combat TB infection, while the Th1 cytokines TNFα and IFNγ are essential for the effective immune response against TB infection. These analyses resulted in the establishment of genotypes and phenotypes detected utilising a novel molecular method and protocols developed specifically for this research. Osteological observations indicated an increase in risk of disease in early contact populations, particularly those associated with infectious disease or the co-infection of multiple conditions compared to the pre-contact cohort. In contrast pre-mortem tooth loss decreased with contact, and degenerative pathologies maintained a relatively balanced presence. TB pathologies were observed in both pre-contact and contact groups, with an increased level of pathologies observed in contact individuals. Molecular results suggest immunogenetic profiles similar to First Nations groups, with only a single cytokine SNP exhibiting a unique phenotype in comparison. Immunogenetic profiles suggest Inuit have maintained a Th2 immune response for many generations, and this remains unchanged with contact.