American cutaneous leishmaniasis is a zoonotic disease caused by protozoans of the genus Leishmania. The treatment of cutaneous leishmaniasis is unsatisfactory, thus, much research effort has been focused on investigating new compounds with lower collateral effects to the patients and derived from low-cost sources, such as natural products. In the present study, we evaluated the in vitro directly effect of the flavonoid quercetin against Leishmania (Viannia) braziliensis. Quercetin inhibited the proliferation of promastigote forms at all tested concentrations, these effect were due to increasing the reactive oxygen species (ROS) production, phosphatidylserine exposure and loss of plasma membrane integrity. Moreover, quercetin reduced the number of parasites in L. braziliensis-infected macrophages, reducing the levels of TNF-α and increasing IL-10 synthesis without modulate nitric oxide (NO) production. In addition, quercetin upregulated Nrf2/HO-1 expression and modulated the labile iron pool in infected macrophages, culminating in a depletion of available iron for L. braziliensis replication.

During the onset of Trypanosoma cruzi infection, an effective immune response is necessary to control parasite replication and ensure host survival. Macrophages have a central role in innate immunity, acting as an important trypanocidal cell and triggering the adaptive immune response through antigen presentation and cytokine production. However, T. cruzi displays immune evasion mechanisms that allow infection and replication in macrophages, favoring its chronic persistence. One potential mechanism is the release of T. cruzi strain Y extracellular vesicle (EV Y), which participate in intracellular communication by carrying functional molecules that signal host cells and can modulate the immune response. The present work aimed to evaluate immune modulation by EV Y in C57BL/6 mice, a prototype resistant to infection by T. cruzi strain Y, and the effects of direct EV Y stimulation of macrophages in vitro. EV Y inoculation in mice prior to T. cruzi infection resulted in increased parasitemia, elevated cardiac parasitism, decreased plasma nitric oxide (NO), reduced NO production by spleen cells, and modulation of cytokine production, with a reduction in TNF-α in plasma and decreased production of TNF-α and IL-6 by spleen cells from infected animals. In vitro assays using bone marrow-derived macrophages showed that stimulation with EV Y prior to infection by T. cruzi increased the parasite internalization rate and release of infective trypomastigotes by these cells. In this same scenario, EV Y induced lipid body formation and prostaglandin E₂ (PGE₂) production by macrophages even in the absence of T. cruzi. In infected macrophages, EV Y decreased production of PGE₂ and cytokines TNF-α and IL-6 24 h after infection. These results suggest that EV Y modulates the host response in favor of the parasite and indicates a role for lipid bodies and PGE₂ in immune modulation exerted by EVs.

Prostaglandins are known to be produced by macrophages when challenged with Trypanosoma cruzi, the etiological agent of Chagas' disease. It is not kn

The intracellular protozoan parasiteTrypanosoma cruzicauses Chagas disease, a serious disorder that affects millions of people in Latin America. Cell invasion byT. cruziand its intracellular replication are essential to the parasite’s life cycle and for the development of Chagas disease. Here, we present evidence suggesting the involvement of the host’s cyclooxygenase (COX) enzyme duringT. cruziinvasion. Pharmacological antagonist for COX-1, aspirin (ASA), caused marked inhibition ofT. cruziinfection when peritoneal macrophages were pretreated with ASA for 30 min at 37°C before inoculation. This inhibition was associated with increased production of IL-1βand nitric oxide (NO∙) by macrophages. The treatment of macrophages with either NOS inhibitors or prostaglandin E₂(PGE₂) restored the invasive action ofT. cruziin macrophages previously treated with ASA. Lipoxin ALX-receptor antagonist Boc2 reversed the inhibitory effect of ASA on trypomastigote invasion. Our results indicate that PGE₂,NO∙, and lipoxins are involved in the regulation of anti-T. cruziactivity by macrophages, providing a better understanding of the role of prostaglandins in innate inflammatory response toT. cruziinfection as well as adding a new perspective to specific immune interventions.

The intracellular protozoan parasite Trypanosoma cruzi is the etiologic agent of Chagas disease, a serious disorder that affects millions of people in Latin America. Cell invasion by T. cruzi and its intracellular replication are essential to the parasite's life cycle and for the development of Chagas disease. Here, we present evidence suggesting the involvement of the host's cyclooxygenase (COX) enzymes during T. cruzi invasion. Pharmacological antagonists for COX-1 (aspirin) and COX-2 (celecoxib) caused marked inhibition of T. cruzi infection when rat cardiac cells were pretreated with these nonsteroidal anti-inflammatory drugs (NSAIDs) for 60 min at 37°C before inoculation. This inhibition was associated with an increase in the production of NO and interleukin-1β and decreased production of transforming growth factor β (TGF-β) by cells. Taken together, these results indicate that COX-1 more than COX-2 is involved in the regulation of anti- T. cruzi activity in cardiac cells, and they provide a better understanding of the influence of TGF-β-interfering therapies on the innate inflammatory response to T. cruzi infection and may represent a very pertinent target for new therapeutic treatments of Chagas disease.

The cellular and molecular pathophysiological mecha\nisms of pain processing in neglected parasitic infections such as leishmaniasis remain unknown. The present study evaluated the participation of spinal cord glial cells in the pathophysiology of pain induced by Leishmania amazonensis infection in BALB/c mice. Mice received intra-plantar (i.pl.) injection of L. amazonensis (1 × 105) and hyperalgesia, and paw edema were evaluated bilaterally for 40 days. The levels of TNF-α and IL-1β, MPO activity, and histopathology were assessed on the 40th day. ATF3 mRNA expression was assessed in DRG cells at the 30th day post-infection. Blood TNF-α and IL-1β levels and systemic parasite burden were evaluated 5–40 days after the infection. At the 30th day post-infection L. amazonensis, the effects of intrathecal (i.t.) treatments with neutralizing antibody anti-CX3CL1, etanercept (soluble TNFR2 receptor), and interleukin-1 receptor antagonist (IL-1ra) on infection-induced hyperalgesia and paw edema were assessed. In another set of experiments, we performed a time course analysis of spinal cord GFAP and Iba-1 (astrocytes and microglia markers, respectively) and used confocal immunofluorescence and Western blot to confirm the expression at the protein level. Selective astrocyte (α-aminoadipate) and microglia (minocycline) inhibitors were injected i.t. to determine the contribution of these cells to hyperalgesia and paw edema. The effects of i.t. treatments with glial and NFκB (PDTC) inhibitors on spinal glial activation, TNF-α, IL-1β, CX3CR1 and CX3CL1 mRNA expression, and NFκB activation were also evaluated. Finally, the contribution of TNF-α and IL-1β to CX3CL1 mRNA expression was investigated. L. amazonensis infection induced chronic mechanical and thermal hyperalgesia and paw edema in the infected paw. Mechanical hyperalgesia was also observed in the contralateral paw. TNF-α, IL-1β, MPO activity, and epidermal/dermal thickness increased in the infected paw, which confirmed the peripheral inflammation at the primary foci of this infection. ATF3 mRNA expression at the ipsilateral DRG of the infected paw was unaltered 30 days post-infection. TNF-α and IL-1β blood levels were not changed over the time course of disease, and parasitism increased in a time-dependent manner in the ipsilateral draining lymph node. Treatments targeting CX3CL1, TNF-α, and IL-1β inhibited L. amazonensis-induced ongoing mechanical and thermal hyperalgesia, but not paw edema. A time course of GFAP, Iba-1, and CX3CR1 mRNA expression indicated spinal activation of astrocytes and microglia, which was confirmed at the GFAP and Iba-1 protein level at the peak of mRNA expression (30th day). Selective astrocyte and microglia inhibition diminished infection-induced ipsilateral mechanical hyperalgesia and thermal hyperalgesia, and contralateral mechanical hyperalgesia, but not ipsilateral paw edema. Targeting astrocytes, microglia and NFκB diminished L. amazonensis-induced GFAP, Iba-1, TNF-α, IL-1β, CX3CR1 and CX3CL1 mRNA expression, and NFκB activation in the spinal cord at the peak of spinal cord glial cells activation. CX3CL1 mRNA expression was also detected in the ipsilateral DRG of infected mice at the 30th day post-infection, and the i.t. injection of TNF-α or IL-1β in naïve animals induced CX3CL1 mRNA expression in the spinal cord and ipsilateral DRG. L. amazonensis skin infection produces chronic pain by central mechanisms involving spinal cord astrocytes and microglia-related production of cytokines and chemokines, and NFκB activation contributes to L. amazonensis infection-induced hyperalgesia and neuroinflammation.