The Placenta Really Does Act Like A Parasite
Main Category: Endocrinology News
Article Date: 13 Nov 2007 - 1:00 PST
The placenta uses a cloaking device similar to that used by parasites
to avoid detection by the mother's immune system. MRC funded
scientists looking to develop a diagnostic test for pre-eclampsia, a
major and potentially fatal cause of fetal and maternal illness, made
the amazing discovery which could have far reaching implications.
The team, based at the University of Reading, believe their findings
will revolutionise our understanding of the placenta and research
into recurrent miscarriages and pre-eclampsia. It is also hoped this
method of avoiding immune rejection could be mimicked and used in
other areas such as arthritis or even stem cell therapy.
At the turn of 21st century Professor Lowry and his team discovered
that the small protein neurokinin B (NKB), which is secreted by the
placenta, is raised significantly in mothers when pre-eclampsia
develops. Because NKB can be detected as early as week 9 of pregnancy
it can be used to predict which women are more at risk of the
condition, which tends to occur in the second and third trimester.
Phil Lowry led the Reading team: "While looking to translate this
discovery into a diagnostic kit we were flummoxed. The placental form
of the protein did not react in the same way as the NKB we had been
using. It became clear that there was a modification occurring during
the synthesis of the protein by the placenta," says Lowry.
"What we found next was most unusual. It appeared the placental NKB
contained the molecule phosphocholine which is used by filarial
nematodes, a type of parasitic worm, to escape host immune systems! I
have had two or three 'Eureka!' moments in my career. This one, at
63, I am happy to bow out on."
The human foetus and placenta have a different genotype from the
mother. The foetus has been described before as acting in a parasitic
way: it avoids rejection by the mother and exerts considerable
influence over her metabolism for its own benefit, in particular
diverting blood and nutrients. Now it would appear the similarities
go much further. Although the mode of attachment of the phosphocoline
(PC) is different in the mammalian placenta, its presence is
startling.
"When we saw this, our immediate instinct was to look at other
proteins in the placenta. So far, from what we have seen, it appears
a large number of them possess this protein surface molecule which
cloaks them from the host immune system," Lowry continued. It is
hoped that this breakthrough will have many applications beyond the
placenta. Already work is being done to investigate how PC-containing
protein segments could help reverse conditions such as rheumatoid
arthritis and other autoimmune disorders.
"Devising a mechanism by which you could make cells invisible to the
immune system could lead to cures for a number of diseases and
conditions. But as many discoveries in science, this presents us with
a whole new can of worms. It will provide work for scientists for
decades to come no doubt," concluded Lowry.
Lowry PJ et al (2007). Identification of a novel mammalian post-
translational modification, phosphocholine, on placental secretory
polypeptides. Journal of Molecular Endocrinology, 39, 189-198. DOI:
10.1677/JME-
http://www.medicaln
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StemCells subscribers may also be interested in these sites:
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Cord Blood Registry
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The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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