Missouri
scientists have identified a gene in mice that, if disabled, prevents a
rheumatoid arthritis-like disorder caused by immune cells.
Rheumatoid arthritis
is triggered when the body's own immune system mistakenly attacks healthy
joint tissues. Scientists now believe the attack may be caused by the innate
immune system, cells that respond generally to infection, including cells
called neutophils.
As part of their
normal function, neutophils secrete toxic chemicals.
They are protected
themselves against the chemicals by the Foxo3a gene.
Knocking out
the gene leaves the cells vulnerable, researchers at the Washington University
School of Medicine in St. Louis discovered. When these cells are mistakenly
attacking healthy joints, however, letting them kill themselves off may
be the answer to preventing arthritis.
The theory is
supported by tests on mice genetically engineered not to have a working
Foxo3a gene. When the mice were injected with antibodies that normally
induce a condition like rheumatoid arthritis they remained healthy.
Further research
showed the neutrophils were self-destructing.
Results of the
study appear in the June issue of Nature Medicine.
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