Humans with osteoarthritis have lots of inflammatory proteins that are made when the body is under attack by a bacterial or viral infection. These proteins, called the complement system, attack the damaged joints just as they would attack a bacteria or virus. The complement system activates a cluster of proteins called the membrane attack complex (MAC).

In osteoarthritis, the MAC promotes the release of enzymes and inflammatory chemicals that chew up cartilage in the joints and spaces between bone cells. When researchers blocked this complement system in mice, the mice were actually protected against osteoarthritis, even when their joints are physically damaged. Read story >

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