P2X7 receptors as targets for neuroprotection.

In this review we explore the potential of P2X7 receptor blockers to elicit neuroprotection. This conjecture is based on a reasonably well-established role of this receptor in activating glial cells to maintain a chronic low-level neuroinflammatory state in the brain of patients suffering some neurodegenerative diseases (NDDs). In this context we briefly discuss evidence supporting the role of P2X7 receptors (P2X7) in the pathogenesis of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, multiple sclerosis, and retinal degeneration. From a pathogenic point of view these diseases have specific features but all share a low level neuroinflammatory state with microglia activation and enhanced P2X7 expression. Next, we comment on available P2X7 blockers with central nervous system (CNS) target engagement. Then, we deal with the proof-of-concept concerning the potential of some blockers to mitigate the neuroinflammatory state in preclinical models of the target diseases above mentioned. We follow with a discussion of the scarce number of clinical trials done with some P2X7 blockers in inflammatory diseases. Finally, we discuss the current discrepancy between promising preclinical data and the limited number of clinical trials exploring P2X7 antagonists in NDDs. We provide some clues that may boost clinical trials with single P2X7 blockers but particularly, with their association with other medicines currently being used or that are intended to be prescribed in the treatment of NDDs.