Using mice, researchers have discovered that fat cells in the knee secrete a protein, known as pro-factor D, which yields another protein, known as factor D (part of the complement system). The complement system is a complex network of pathways involving over 40 proteins that play a significant role in our immune system. It had been determined previously that factor D made mice susceptible to developing inflammatory arthritis (e.g., rheumatoid arthritis).
According to the findings, published in the Journal of Immunology, the discovery of pro-factor D in mice may lead to gene therapies or other treatments to inhibit pro-factor D. Being able to target pro-factor D, as opposed to the entire complement system, would leave intact the beneficial aspects of the complement system (e.g., fighting infection).
It is known that fat is present around all of the body's organs, but it was not previously known that fat was secreting a protein which can trigger arthritis. Fat affects all joints in this way, not just the knees. Of course, this would need to be applicable to humans, but every bit of new arthritis research offers hope.
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