Bernd Brägelmann [creativecommons license] via Wikimedia CommonsRheumatoid arthritis is a chronic, destructive inflammation, primarily of the joints, that affects up to 1% of the world’s population. The cause of the disease is not known, but its progression is autoimmune: immune cells called macrophages, which normally die after attacking an invader, instead persist and collect in the cartilage and bone, where their proliferation results in inflammation and joint destruction. The proliferation is thought to stem from an imbalance or deficiency in the signaling pathways for apoptosis (programmed cell death). Currently available treatments for rheumatoid arthritis include chemotherapy and steroid administration, but these are not effective in all patients and may have unwanted side effects. Now, Harris Perlman (Northwestern University, Feinberg School of Medicine, Chicago, IL) and colleagues report that expression of Bim, a pro-apoptotic protein, is deficient in joints affected by rheumatoid arthritis and that treatment with a molecule similar to Bim protected mice against rheumatoid arthritis and even reversed the disease course in mice that had already developed rheumatoid arthritis.
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