Parkinson's disease is characterized by a slow progression of a specific neuronal population in the brain using dopamine as neurotransmitter. Previous studies performed by several groups of researchers around the world, including us, show that non-neuronal cells are very likely to participate in the slow progression of neuronal degeneration in Parkinson's disease. Such a deleterious effect is mediated by the production of toxic compounds known as proinflammatory cytokines. Yet, the exact nature of the cells producing these cytokines is not fully known. In the present research program, performed with Dr. Stephane Hunot, we will determine if cells from the blood vessels, such as lymphocytes penetrate into the brain and produce proinflammatory cytokines. Preliminary experiments suggest that it is the case. We will thus investigate the mechanism of lymphocytes entry into the brain, their role in neuronal degeneration and the molecular events underlying this phenomenon. Our hope is that understanding such mechanisms may help us to identify therapeutic targets for Parkinson's disease.