Macrophage P2X4 receptors augment bacterial killing and protect against sepsis

Abstract

The macrophage is a major phagocytic cell type, and its impaired function is a primary cause of immune paralysis, organ injury, and death in sepsis. An incomplete understanding of the endogenous molecules that regulate macrophage bactericidal activity is a major barrier for developing effective therapies for sepsis. Using an in vitro killing assay, we report here that the endogenous purine ATP augments the killing of sepsis-causing bacteria by macrophages through P2X4 receptors (P2X4Rs). Using newly developed transgenic mice expressing a bioluminescent ATP probe on the cell surface, we found that extracellular ATP levels increase during sepsis, indicating that ATP may contribute to bacterial killing in vivo. Studies with P2X4R-deficient mice subjected to sepsis confirm the role of extracellular ATP acting on P2X4Rs in killing bacteria and protecting against organ injury and death. Results with adoptive transfer of macrophages, myeloid-specific P2X4R-deficient mice, and P2rx4 tdTomato reporter mice indicate that macrophages are essential for the antibacterial, antiinflammatory, and organ protective effects of P2X4Rs in sepsis. Pharmacological targeting of P2X4Rs with the allosteric activator ivermectin protects against bacterial dissemination and mortality in sepsis. We propose that P2X4Rs represent a promising target for drug development to control bacterial growth in sepsis and other infections.

Extracellular ATP as an Inter-Kingdom Signaling Molecule: Release Mechanisms by Bacteria and Its Implication on the Host

“…Sepsis is a life-threatening organ dysfunction caused by a dysregulated immune response to invading bacteria, which leads to extensive damage locally but also remote from the primary site of infection [105,106]. Purinergic signaling has been shown to influence septic outcome in various studies [19,21,[107][108][109][110][111] and it is therefore conceivable that bacterial ATP is able to activate purinergic receptors and to influence septic outcome as well. It is highly likely that eATP concentration in the surrounding of a bacterium or a bacterial colony is much higher in a halo-like manner than the diluted eATP concentration measured in the supernatant mentioned above.…”

Mitochondria Synergize With P2 Receptors to Regulate Human T Cell Function

“…At the same time, excessive P2Y2 receptor stimulation by systemic ATP aggravates inflammatory neutrophil responses such as oxidative burst and degranulation, which culminate a in neutrophil-mediated collateral host tissue damage ( Figure 2 ) ( 100 – 102 ). Systemic ATP may have a similar impact on other immune cells including macrophages that depend on P2X4 and P2X7 receptors for bacterial clearance in polymicrobial sepsis ( 103 , 104 ). Targeting extracellular ATP could be a promising approach to overcome systemic inflammation and immunosuppression in critical care and cancer patients.…”

To Inhibit or Enhance? Is There a Benefit to Positive Allosteric Modulation of P2X Receptors?

“…In T lymphocytes, P2X4 can affect T cell activation and migration (Woehrle et al, 2010;Ledderose et al, 2018). In monocytes/macrophages, P2X4 has been linked to release of the chemokine CXCL5 (Layhadi et al, 2018) and the killing of E. coli bacteria (Csoḱa et al, 2018). In the latter study, macrophages taken from the P2X4 -/mouse failed to kill bacteria in response to ATP (Csoḱa et al, 2018).…”