The purinoreceptors are divided into inotropic (P2XR) and metabotropic (P2YR) subtypes whose ligands are the nucleotides ATP and UDP respectively (Cekic et al. 2016). The binding of these nucleotides to their receptors on macrophages have been associated with the activation of the inflammasome leading to the subsequent activation of interleukin 1 beta (IL1β) and TNF-α (Cekic et al. 2016 & Figueiredo et al. 2016). The liberation of ATP comes from tissues facing stressful stimuli such as a tissue injury or microorganism infection, amongst others. As a regulatory mechanism, certain enzymes can reduce ATP to Adenosine and a nucleoside can stimulate signalling pathways leading to the synthesis of anti-inflammatory cytokines (Cekic et al. 2016).
The activation of the receptor P2RX7 was shown to lead to the activation of killing mechanisms or cell death programs, ending up in the elimination of microbes such as Leishmania amazonensis, Mycobacterium tuberculosis, Chlamydia psittaci, and Toxoplasma gondii (Coutinho-Silva et al. 2012 & Idzko, 2014).