Peroxisome Proliferator-Activated Receptor Gamma Agonists

Abstract

Inflammatory processes play a central role in a number of diseases afflicting the nervous system. There is considerable controversy over whether inflammatory mechanisms are the cause or consequence of neurodegenerative changes. Moreover, if inflammatory changes are secondary to more primary neuropathological changes, do they exacerbate neuronal dysfunction and promote cell death? In some neurological diseases, the inflammatory cells are the primary effectors of the pathology; for example, in multiple sclerosis, T cells direct macrophage-mediated loss of myelin. In other diseases such as stroke, peripheral leukocytes are recruited to the lesion site along with the parallel activation of the endogenous microglia. These cells act in concert to mount a robust pro-inflammatory response that greatly expands and exacerbates the primary infarct. Traumatic brain injury is also associated with inflammatory cell infiltration and induction of a local inflammatory response. More recently, human immunodeficiency virus (HIV) and CreutzfeldtJakob disease have been shown to have an inflammatory component arising secondary to the primary neuropathological process. The involvement of an inflammatory component in the etiology of Alzheimer’s disease (AD) has recently received considerable attention (1). Indeed, the only demonstrated effective therapy for AD patients is long-term treatment with nonsteroidal anti-inflammatory drugs (NSAIDs). The mechanistic basis of the efficacy of NSAIDs in AD remains unclear. However, the recent recognition that NSAIDs can bind to and activate the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) has offered an explanation for the efficacy of these drugs in AD and has opened new therapeutic approaches to this disease. Indeed, the newly appreciated anti-inflammatory actions of PPARγ agonists may allow novel therapies for other central nervous system (CNS) indications with an inflammatory component.