Archive for the ‘Rheumatoid arthritis’ Category
New clues about the cause of rheumatoid arthritis
The study, published in the latest issue of Nature Genetics, Dr. Katherine Siminovitch and his team identified the exact means by which an alteration in the gene PTPN22 increases the risk of rheumatoid arthritis and other autoimmune diseases. The study uses advanced technologies of genomics to enable testing on millions of genetic markers in a single experiment to identify genes that confer a risk for the disease, such as PTPN22.
The team generated a genetic model in mice to show how the PTPN22 gene mutation impairs the cellular immune function, and then validated their results in humans. As a result obtained a more accurate understanding of how autoimmune diseases develop and how new diagnostic tests and targeted therapies can be designed to better control of symptoms and potential cure.
“Our findings are particularly interesting because this study sets a new precedent for the study of arthritis and other autoimmune diseases,” said lead author, Dr. Siminovitch Mount Sinai Hospital and professor at the University of Toronto. The doctor adds that “this is one of the first studies in which we have traced the steps that connect a specific genetic lesions with the development of an autoimmune condition, common and complex.”
The research team used genetically engineered mice in which the PTPN22 gene was altered to simulate a genetic mutation that is found in many patients with RA. He looked at the effects of this change in immune cells in mice, and studies were repeated in human blood samples from patients with and without AR. Thus, the group focused on the impact of a protein called ‘Lyp / Pep’ which, in healthy cells, preventing hyper-immune responses responsible for autoimmune disorders. The group noted that mutation of the gene leads to decreased levels of Lyp, thereby removing the natural brake that normally prevents the inflammatory processes underlying RA and many other autoimmune disorders.
“Measuring the levels of this protein will help control the severity of the disease in patients with autoimmune diseases, testing the effects of various therapies (including new drugs), and determine which treatments work best for each patient,” says Dr. Edward Keystone, study co-author and director of the Centre for Arthritis and Autoimmune Disease at Mount Sinai.
Dr. Keystone stressed the importance of such research in the practice of medicine in general, taking into account advances in genetic knowledge are enabling earlier diagnosis and more personalized treatments, providing patients with better results. “With the use of powerful genetic tools available, disease, previously cryptic, dissected to identify their underlying causes,” concludes Dr. Jim Woodgett, a researcher at Mount Sinai hospital.