Mice Lacking the Purinergic Receptor P2X5 Exhibit Defective Inflammasome Activation and Early Susceptibility to Listeria monocytogenes.

P2X5 is a member of the P2X purinergic receptor family of ligand-gated cation channels and has recently been shown to regulate inflammatory bone loss. In this study, we report that P2X5 is a protective immune regulator during Listeria monocytogenes infection, as P2X5-deficient mice exhibit increased bacterial loads in the spleen and liver, increased tissue damage, and early (within 3-6 d) susceptibility to systemic L. monocytogenes infection. Whereas P2X5-deficient mice experience normal monocyte recruitment in response to L. monocytogenes, P2X5-deficient bone marrow-derived macrophages (BMMs) exhibit defective cytosolic killing of L. monocytogenes We further showed that P2X5 is required for L. monocytogenes-induced inflammasome activation and IL-1ß production and that defective L. monocytogenes killing in P2X5-deficient BMMs is substantially rescued by exogenous IL-1ß or IL-18. Finally, in vitro BMM killing and in vivo L. monocytogenes infection experiments employing either P2X7 deficiency or extracellular ATP depletion suggest that P2X5-dependent anti-L. monocytogenes immunity is independent of the ATP-P2X7 inflammasome activation pathway. Together, our findings elucidate a novel and specific role for P2X5 as a critical mediator of protective immunity.

The purinergic receptor P2X5 contributes to bone loss in experimental periodontitis.

Purinergic receptor signaling is increasingly recognized as an important regulator of inflammation. The P2X family purinergic receptors P2X5 and P2X7 have both been implicated in bone biology, and it has been suggested recently that P2X5 may be a significant regulator of inflammatory bone loss. However, a role for P2X5 in periodontitis is unknown. The present study aimed to evaluate the functional role of P2X5 in ligatureinduced periodontitis in mice. Five days after placement of ligature, analysis of alveolar bone revealed decreased bone loss in P2rx5-/- mice compared to P2rx7-/- and WT control mice. Gene expression analysis of the gingival tissue of ligated mice showed that IL1b, IL6, IL17a and Tnfsf11 expression levels were significantly reduced in P2rx5-/- compared to WT mice. These results suggest the P2X5 receptor may regulate bone loss related to periodontitis and it may thus be a novel therapeutic target in this oral disease. [BMB Reports 2018; 51(9): 468-473].