Wattegedera, S., Doull, L., Goncheva, M.I., Wheelhouse, N.M., Watson, D.M., Pearce, J., Benavides, J., Palarea Albaladejo, J., McInnes, C.J., Ballingall, K.T. and Entrican, G.
Frontiers in Immunology 9, 3025. Frontiers.
ovine, major histocompatibility complex, indoleamine 2, 3 dioxygenase-1, synepitheliochorial placentation, trophoblast
||Successful mammalian pregnancies are a result of complex physiological,
endocrinological, and immunological processes that combine to create an environment
where the mother is tolerant to the semi-allogeneic fetus. Our knowledge of the
mechanisms that contribute to maternal tolerance is derived mainly from human and
murine studies of haemochorial placentation. However, as this is the most invasive
type of placentation it cannot be assumed that identical mechanisms apply to the
less invasive epitheliochorial placentation found in other species such as ruminants.
Here, we examine three features associated with reproductive immune regulation in a
transformed ovine trophoblast cell line and ex-vivo ovine reproductive tissues collected
at term, namely: major histocompatibility complex (MHC) expression, Indoleamine 2,
3 dioxygenase-1 (IDO-1) expression, and Natural Killer (NK) cell infiltration. High levels
of MHC class I protein expression were detected at the surface of the trophoblast cell
line using a pan-MHC class I specific monoclonal antibody. The majority of MHC class I
transcripts isolated from the cell line clustered with classical MHC alleles. Transcriptional
analysis of placental tissues identified only classical MHC class I transcripts. We found
no evidence of constitutive transcription of IDO-1 in either the trophoblast cell line
or placental tissues. Ex-vivo tissues collected from the materno-fetal interface were
negative for cells expressing NKp46/NCR1. Collectively, these observations suggest
that the relatively non-invasive synepitheliochorial placentation found in sheep has a
more limited requirement for local immunoregulation compared to the more invasive
haemochorial placentation of primates and rodents.