Is arthritis caused by a build-up of surplus DNA?
Mice that cannot degrade surplus DNA develop arthritis, according to a new study. If the same occurs in humans, the discovery may suggest new treatments for the inflammatory disorder, researchers say.
Rheumatoid arthritis is an often-crippling inflammation of the joints that afflicts two million people in the US alone. Now, Japanese scientists have discovered that mice which cannot degrade "garbage" DNA develop a condition very similar to human arthritis.
We dump a lot of DNA. Between the newly-made red blood cells that eject their nuclei before joining the circulation, and the many cells that die normally, we dispose of 10 to the 18th – a billion billion – genomes’ worth every day. This garbage DNA is normally engulfed by scavenging white blood cells, called macrophages, which then degrade it using an enzyme called DNase II.
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The researchers conclude that macrophages gorged with DNA they cannot digest turn on TNF-alpha production, which leads to chronic inflammation in the joint, causing arthritis.
We get rid of a billion billion genomes a day! The body is astonishing.