Modulation of P2X7 purinergic receptor in macrophages by Leishmania amazonensis and its role in parasite elimination

Abstract

The purinergic P2X(7) receptor is a membrane protein of leucocytes involved in the clearance of intracellular bacteria such as Chlamydia and Mycobacterium. In this work, we investigated the role and modulation of macrophage P2X(7)R in intracellular infection with the protozoan parasite Leishmania amazonensis. Upon infection, isolated murine macrophages displayed enhanced expression of P2X(7)R and were significantly more responsive to extracellular ATP (ATPe)-induced pore opening, as demonstrated by the increased uptake of Lucifer Yellow. This was extended to the in vivo situation, where cells from established cutaneous lesions were more sensitive to ATPe than cells from uninfected mice. ATP treatment of infected macrophages inhibited parasite growth, and this was prevented by pre-treatment with oxidized ATP, a selective antagonist of P2X(7)R. Parasite killing was unlikely due to induction of nitric oxide production or cytolysis of infected macrophage, as those functions were unaltered with parasite-effective ATPe concentrations. A direct drug effect is also unlike, as ATPe enhanced axenic parasite growth. We found that leishmanial infection rendered wild-type but not P2X(7)R-deficient macrophages more prone to ATP-induced apoptosis. These results show that macrophage infection with L. amazonensis leads to enhanced expression of functional P2X(7)R, that upon ligation with ATPe helps in the elimination of the parasites by an as yet unclear mechanism possibly involving host cell apoptosis.

Leukotriene B4 Modulates P2X7 Receptor–MediatedLeishmania amazonensisElimination in Murine Macrophages

“…Our group has recently demonstrated the involvement of extracellular nucleotides such as ATP and UTP in the elimination of L. amazonensis (12,25). We demonstrated that the elimination of L. amazonensis induced by ATPe is independent of NO production but does involve increased apoptosis of infected cells.…”

“…These receptordependent mechanisms were described by our group as modulators of infections caused by bacterial pathogens and protozoa (10,11). Our group showed that ATPe was able to decrease the parasite load of macrophages infected with L. amazonensis and that these macrophages overexpress P2X7 receptor (12). Furthermore, P2 receptors have been associated with the modulation of lipid metabolism (13).…”

“…We and others have suggested the participation of P2X7 receptors in ATP-induced control of many intracellular parasites (10,11), including in L. amazonensis-infected macrophages (12). To test the involvement of the P2X7 receptor in the elimination mechanism of L. amazonensis, we used macrophages from P2X7 receptor-deficient mice.…”

P2X7 receptor in skin biology and diseases

“…P2X7 activation on human and murine macrophages results in the release of proinflammatory mediators such as IL-1b and prostaglandin E2 [51] , as well as the production of reactive oxygen species [52] , and killing of intracellular mycobacteria [53] , chlamydia [54] and toxoplasma [55] . Of note, P2X7 activation eliminates Leishmania amazonensis, the causative agent of human cutaneous leishmaniasis [56] , within murine peritoneal macrophages [57] , supporting the potential importance of macrophage P2X7 in skin biology.…”

Lipid metabolism modulation by the P2X7 receptor in the immune system and during the course of infection: new insights into the old view

“…3). Conversely, macrophages infected with Leishmania amazonensis upregulate P2X7R, which, when activated by ATP, induces reduction of parasitic load and consequent cell death [116]. Unlike other pathogens, L. amazonensis maintains the acidification of the parasitophorous vacuole to survive, and so it is possible that the role of P2X7R in parasite elimination is through an alternative pathway.…”