Abstract
Adenosine is an endogenous purine nucleoside that, subsequent to its release from cells or after being generated extracellularly, diffuses to the membrane of surrounding cells, in which it binds to specific cell surface structures that recognize it, termed adenosine receptors. There are four types of adenosine receptors, all of which are members of the G-protein-coupled family of receptors. They are the A1, A2A, A2B, and A3 adenosine receptors. 1-4 Although adenosine is present at low concentrations in the extracellular space, metabolically stressful conditions increase its extracellular levels dramatically. Adenosine receptors are expressed abundantly on cells of the monocyte/macrophage lineage, and through these receptors adenosine exerts substantial modulatory effects on monocyte/macrophage function. 5-7 Because macrophages are activated by stressful stimuli such as inflammation, hypoxia, and ischemia, the same stimuli that can result in accumulation of extracellular adenosine, adenosine receptors expressed on macrophages represent a sensor system providing macrophages with essential information about the inflammatory or ischemic environment. 6 This mechanism allows macrophages to fine-tune their responses to stressful stimuli. In this chapter, we focus on the consequences of adenosine receptor engagement on monocyte and macrophage function. We will delineate the effect of stimulating the various adenosine receptor subtypes on macrophage differentiation/proliferation, phagocytosis, membrane protein expression, and mediator production. A more complete understanding of the regulation of monocyte/macrophage function by adenosine receptor engagement should help develop novel therapeutic ways of manipulating disorders that are associated with exuberant or insufficient macrophage activation.
Original language | English (US) |
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Title of host publication | Adenosine Receptors |
Subtitle of host publication | Therapeutic Aspects for Inflammatory and Immune Diseases |
Publisher | CRC Press |
Pages | 49-68 |
Number of pages | 20 |
ISBN (Electronic) | 9781420005776 |
ISBN (Print) | 0849339995, 9780849339998 |
State | Published - Jan 1 2006 |
Externally published | Yes |
ASJC Scopus subject areas
- General Pharmacology, Toxicology and Pharmaceutics
- General Immunology and Microbiology
- General Medicine