Intralesional uridine-5′-triphosphate (UTP) treatment induced resistance to Leishmania amazonensis infection by boosting Th1 immune responses and reactive oxygen species production

Abstract

Leishmania amazonensis is the etiologic agent of cutaneous leishmaniasis, an immune-driven disease causing a range of clinical symptoms. Infections caused by L. amazonensis suppress the activation and function of immune cells, including macrophages, dendritic cells, and CD4 T cells. In this study, we analyzed the course of infection as well as the leishmanicidal effect of intralesional UTP treatment in L. amazonensis-infected BALB/c mice. We found that UTP treatment reduced the parasitic load in both footpad and lymph node sites of infection. UTP also boosted Th1 immune responses, increasing CD4 T cell recruitment and production of IFN-γ, IL-1β, IL-12, and TNF-α. In addition, the role of UTP during innate immune response against L. amazonensis was evaluated using the air pouch model. We observed that UTP augmented neutrophil chemoattraction and activated microbicidal mechanisms, including ROS production. In conclusion, our data suggested an important role for this physiological nucleotide in controlling L. amazonensis infection, and its possible use as a therapeutic agent for shifting immune responses to Th1 and increasing host resistance against L. amazonensis infection.

P2Y2 Receptor Induces L. amazonensis Infection Control in a Mechanism Dependent on Caspase-1 Activation and IL-1β Secretion

“…We recently reported that UTP-intralesional treatment elicited a Th 1 immune response in an experimental model of cutaneous leishmaniasis [ 21 ], suggesting the involvement of P2Y 2 R. Here, we evaluated whether the intralesional treatment with a selective P2Y 2 R agonist (2-thio-UTP) would promote L. amazonensis control in BALB/c mice. As shown in Figure 1(a) , tissues were harvested for analysis at 26 d.p.i.…”

“…We previously reported the involvement of purinergic receptors, including P2Y 2 R and P2X7R, in the control of L. amazonensis infection in vitro and in vivo [ 4 , 19 ]. These receptors induce the activation of several microbicidal mechanisms in host cells during infection (i.e., NO, ROS, LTB 4 production) [ 20 , 21 , 26 , 27 ]. Here, we identified a protective mechanism triggered by P2Y 2 R, using incubation with either a specific agonist for P2Y 2 R, 2-thio UTP, or low concentrations of UTP (100 μ M) or ATP (50 μ M) during in vitro infection with L. amazonensis .…”

“…ATP/P2X7R signaling during L. amazonensis infection has been partially elucidated during the last decade; it is assumed to be the most potent canonical activator of the NLRP3 inflammasome [ 16 ] and more recently in noncanonical activation of NLRP3 inflammasome assembly [ 14 , 17 , 18 ]. We previously demonstrated that the antiparasite immune response attributed to the P2YR agonist UTP involves paracrine activation of the P2X7 receptor (P2X7R) and PANX-1 channels in macrophages from mice infected with L. amazonensis [ 19 ]; UTP induces production and release of reactive oxygen species (ROS), nitrite oxide (NO) [ 20 , 21 ], and leukotriene B 4 (LTB 4 ) [ 19 ] that is assumed to be crucial for parasite death. In addition to these inflammatory mediators, IL-1 β mediates the control of intracellular parasite infections [ 4 ] [ 22 ].…”

Purinergic Cooperation Between P2Y2 and P2X7 Receptors Promote Cutaneous Leishmaniasis Control: Involvement of Pannexin-1 and Leukotrienes

“…In previous studies, we showed that ATP secreted after cell lysis can control the survival of the protozoan parasites Plasmodium chabaudi and Toxoplasma gondii ( 24 , 25 ), in a mechanism involving ROS production ( 26 ). We also showed that Leishmania amazonensis infection positively modulates the expression of P2X7, P2Y 2 , and P2Y 4 receptors in macrophages ( 19 , 20 ), and that the activation of P2 receptors by nucleotide secretion is likely to represent a physiological mechanism for parasitism control ( 5 ), since UTP and ATP have crucial roles in restraining the proliferation of L. amazonensis ( 19 , 20 , 27 ). P2X7 receptor activation induces resistance to L. amazonensis infection in macrophages, via a mechanism involving LTB 4 production ( 5 ).…”

“…Our group has been reporting the involvement of extracellular nucleotides such as UTP and ATP in restraining the replication of L. amazonensis ( 5 , 19 , 20 , 27 ). Recent evidence suggests that the presence of ATP in the extracellular environment can trigger further ATP release for different human cell types—including leukocytes, urothelial cells, osteocytes, neutrophils, and macrophages ( 37 , 38 ).…”