Y-chromosome DNA Is Present in the Blood of Female Dogs Suggesting the Presence of Fetal Microchimerism

Abstract

Fetal microchimerism has been suggested to play contradictory roles in women’s health, with factors including age of the recipient, time elapsed since microchimerism occurred, and microchimeric cell type modulating disease. Both beneficial and harmful effects have been identified in wound healing and tissue regeneration, immune mediated disease, and cancer. This area of research is relatively new, and hindered by the time course from occurrence of fetal microchimerism to the multi-factorial development of disease. Dogs represent an excellent model for study of fetal microchimerism, as they share our environment, have a naturally condensed lifespan, and spontaneously develop immune-mediated diseases and cancers similar to their human counterparts. However, fetal microchimerism has not been described in dogs. These experiments sought preliminary evidence that dogs develop fetal microchimerism following pregnancy. We hypothesized that Y chromosomal DNA would be detected in the peripheral blood mononuclear cells of female dogs collected within two months of parturition. We further hypothesized that Y chromosomal DNA would be detected in banked whole blood DNA samples from parous female Golden Retrievers with at least one male puppy in a prior litter. Amplification of DNA extracted from five female Golden Retrievers that had whelped within the two months prior to collection revealed strong positive bands for the Y chromosome. Of banked, parous samples, 36% yielded positive bands for the Y chromosome. This is the first report of persistent Y chromosomal DNA in post-partum female dogs and these results suggest that fetal microchimerism occurs in the canine species. Evaluation of the contributions of fetal microchimeric cells to disease processes in dogs as a model for human disease is warranted.

Fetal microchimerism and maternal health: A review and evolutionary analysis of cooperation and conflict beyond the womb

“…Microchimerism has thus far only been detected in eutherian mammals [14,[27][28][29], suggesting it arose at least in the common ancestor of eutherian mammals, approximately 93 million years ago [112] Here, we describe the proximate, developmental, evolutionary, and phylogenetic explanations of microchimerism. capacity of fetal cells to manipulate maternal tissues to the mother's fitness detriment.…”

Immunological implications of pregnancy-induced microchimerism

“…Fetal cells identified by Y-chromosome or HLA-haplotype DNA persist in many lymphoid and non-lymphoid tissues, and amongst multiple cell types, in mothers after parturition (reviewed in REFS 61,62 ) (Supplementary information S1 (Table)). The retention of fetal cells in maternal tissues is also highly conserved across mammalian species, which suggests that there are likely to be biological benefits that drive the maintenance of tolerance to fetal antigens in mothers after pregnancy 9,23,63 .…”

Fetal Microchimerism in Cancer Protection and Promotion: Current Understanding in Dogs and the Implications for Human Health

“…Recently, our laboratory undertook an examination of peripheral blood DNA samples from 90 parous golden retrievers with a history of male puppies in at least one litter [11]. A nested PCR assay for Y chromosomal DNA was developed with a sensitivity of male cell identification between 1 in 60,000 and 90,000 female nucleated cells.…”

“…The compressed life-span of dogs and relatively high-quality medical care they receive allow for rapid accumulation of detailed health and disease observations. Recently, male fetal microchimerism was identified in parous companion golden retrievers [11]. Subsequent work has also identified the phenomenon in Dachshunds, with evidence for the existence of sibling microchimerism from prior litters [12].…”