Combined Therapy of A(1)AR Agonists and A(2A)AR Antagonists in Neuroinflammation

Alzheimer’s, Parkinson’s, and multiple sclerosis are neurodegenerative diseases related by neuronal degeneration and death in specific areas of the central nervous system. These pathologies are associated with neuroinflammation, which is involved in disease progression, and halting this process represents a potential therapeutic strategy. Evidence suggests that microglia function is regulated by A(1) and A(2A) adenosine receptors (AR), which are considered as neuroprotective and neurodegenerative receptors, respectively. The manuscript’s aim is to elucidate the role of these receptors in neuroinflammation modulation through potent and selective A(1)AR agonists (N(6)-cyclopentyl-2′- or 3′-deoxyadenosine substituted or unsubstituted in 2 position) and A(2A)AR antagonists (9-ethyl-adenine substituted in 8 and/or in 2 position), synthesized in house, using N13 microglial cells. In addition, the combined therapy of A(1)AR agonists and A(2A)AR antagonists to modulate neuroinflammation was evaluated. Results showed that A(1)AR agonists were able, to varying degrees, to prevent the inflammatory effect induced by cytokine cocktail (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and interferon (IFN)-γ), while A(2A)AR antagonists showed a good ability to counteract neuroinflammation. Moreover, the effect achieved by combining the two most effective compounds (1 and 6) in doses previously found to be non-effective was greater than the treatment effect of each of the two compounds used separately at maximal dose.