MIKROBIT/AUTOIMMUUNISAIRAUDET

[Bb]

Lähettäjä: Soijuv Lähetetty: 26.9.2005 11:11

Mikrobien aiheuttamat infektiot voivat laukaista
ja/tai pahentaa autoimmuunisairauksia:


How bacteria break B cell tolerance
23 Jul 2005

There is a lot of indirect evidence that microbial infections can initiate
and/or worsen autoimmune disease. Autoantibody production during infection
results from activation of low-affinity autoreactive B cells. But how this
could lead to autoimmune disease is not clear.

In a study appearing online on July 21 in advance of print publication of
the August 1 issue of the Journal of Clinical Investigation, Thierry Martin
and colleagues from INSERM show in vivo that experimental infection with
Borrelia burgdorferi creates the necessary and sufficient conditions to
activate self-reactive B cells with significant affinity. This could drive
them to mature into harmful memory B cells and lead to autoimmune diseases
in susceptible individuals.

Title: Autoantigen, innate immunity and T cells cooperate to break B cell
tolerance during bacterial infection
http://www.jci.org/cgi/content/abstract/JCI24646v1

Martin Thierry
INSERM, Strasbourg, France

Stacie Bloom
press_releases@the-jci.org
212-342-4159
Journal of Clinical Investigation
http://www.jci.org
How bacteria break B cell tolerance
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Bacteria use host's immune response to their competitive advantage
22 Jul 2005

Millions of bacteria live within the recesses of our noses and upper
respiratory tracts, waiting for a chance to infiltrate and infect. But long
before these bacteria break through our immune defenses, they must first
compete against other bacterial species to colonize the mucus-lined surfacesof our noses.

Competition between two common nose bacteria involves some interesting
trickery, according to a new study in PLoS Pathogens. "We're looking at how
bacteria use their host, and we've found that the presence of one species
leads to the elimination of another," says Jeffrey Weiser, coauthor of the
study and professor of pediatrics and microbiology at the University of
Pennsylvania, School of Medicine.

In a mouse model, Haemophilus influenzae--a common bacterium that infects
children--stimulates the immune system to send out specialized white blood
cells that attack its competitor, Streptococcus pneumoniae--a leading cause
of pneumonia. "It is striking that the host's response can so completely
eliminate the competitor," says Weiser.

The findings also demonstrate how antibiotics and vaccines that target one
microbe might inadvertently alter the competitive interactions among other
species present.

Citation: Lysenko ES, Ratner AJ, Nelson AL, Weiser JN (2005) The role of
innate immune responses in the outcome of interspecies competition for
colonization of mucosal surfaces. PLoS Pathogens 1(1): e1.

LINK TO THE PUBLISHED ARTICLE
dx.doi.org/10.1371/journal.ppat.0010001

CONTACT:
Jeffrey N. Weiser M.D.
University of Pennsylvania School of Medicine
402A Johnson Pavilion
3610 Hamilton Walk
Philadelphia, PA 19104-6076
215-573-3511; FAX 215-573-4856
weiser@mail.med.upenn.edu