Adenosine receptors and acute kidney injury: perspectives for future therapy

Adenosine is a key modulator in the pathophysiology of acute kidney injury (AKI), particularly through its influence on inflammatory pathways and renal hemodynamics. This nucleoside exerts its effects via four G protein-coupled receptors-A1, A2A, A2B, and A3-each displaying distinct roles during renal injury. The A1 receptor primarily protects renal tissue under ischemic conditions by reducing metabolic demand, while the A2A receptor promotes anti-inflammatory and vasodilatory effects, improving renal perfusion and attenuating leukocyte infiltration. The A2B receptor, upregulated under hypoxic or injury conditions, is involved in anti-inflammatory actions and vascular integrity, especially in renal tubular and endothelial cells. Conversely, activation of the A3 receptor is generally linked to adverse outcomes, including increased apoptosis and greater tissue damage. Therapeutic strategies targeting adenosine receptors are being actively explored: selective A1 and A2A agonists show potential for promoting renal recovery, while A3 antagonists helped counteract the harmful effects of A3 activation. The review also discusses advances from recent studies (2022-2024), including insights on COVID-19-associated AKI and the nuanced roles of A1 and A3 receptors in different pathological contexts. Additionally, the therapeutic promise of inhibiting adenosine-degrading enzymes, such as ADA and adenosine kinase (ADK), is highlighted. Novel mechanistic insights and recent literature are integrated, providing a comprehensive overview that expands upon previous reviews. Although adenosine receptor modulation holds significant promise as a therapeutic strategy for AKI, further clinical research is necessary to validate efficacy and safety in human populations.