*, em p /em ? ?0.05, ***, em p /em ? ?0.001 untreated (NT) vs. of duplicates. (TIFF 1430?kb) 12974_2017_952_MOESM4_ESM.tif (1.3M) GUID:?B4314C11-1FCB-4B1E-993C-2085E80C77E6 Additional File 5: Figure S5: Pre-exposing astrocyte cultures to rTNF enhances parasite load in infection. Human astrocytes were submitted to treatment with rTNF and left non-infected (NI) or infected by (MOI 1:1). At 4?h of infection, supernatants were collected and submitted to detection of cytokines by CBA. Data are presented as means SEM of triplicates. *, strain at a MOI of 1 1:1 or 10:1. (b) After 4?h of interaction, the frequencies of infected cells and the number in untreated (NT), rTNF-treated astrocytes are shown. (c) Data show the frequencies of infected astrocytes stratified by classes according to the number of amastigote-like forms harbored in the cytoplasm. Data are presented as means SEM of triplicates. *, infection, interferon gamma (IFN)+ microglial cells surround astrocytes harboring amastigote parasites. In vitro, IFN fuels astrocyte infection by infection and the regulation of cytokine production. Methods Primary astrocyte cultures of neonatal C57BL/6 and C3H/He mice and the human U-87 MG astrocyte lineage were infected with the Colombian strain. Cytokine production, particularly TNF, and TNF receptor 1 (TNFR1/p55) expression were analyzed. Recombinant cytokines (rIFN and rTNF), the anti-TNF antibody infliximab, and the TNFR1 modulator pentoxifylline were used to assess the in vitro effects of TNF on Grapiprant (CJ-023423) astrocyte susceptibility to infection. To investigate the role of TNF on CNS colonization by infection drove astrocytes to a pro-inflammatory profile with TNF and interleukin-6 production, which was amplified by rTNF treatment. Adding rTNF prior to infection fueled parasite growth and trypomastigote egression, in parallel with increased TNFR1 Grapiprant (CJ-023423) expression. Importantly, pentoxifylline inhibited the TNF-induced increase in astrocyte susceptibility to invasion. In invasion of mouse and human astrocytes. Moreover, the TNF-enriched inflammatory milieu and enhanced TNFR1 expression may favor TNF signaling, astrocyte colonization by and egression of trypomastigotes. Therefore, in infection, a self-sustaining TNF-induced inflammatory circuit may perpetuate the parasite cycle in the CNS and ultimately promote cytokine-driven behavioral alterations. Electronic supplementary material The online version of this article (doi:10.1186/s12974-017-0952-0) contains supplementary material, which is available to authorized users. mRNA and nearly undetectable mRNA, neither of which are upregulated after exposure to interferon gamma (IFN) or TNF [10]. TNF and interleukin (IL)-6, another pro-inflammatory cytokine, are positively correlated with the rate of neuronal apoptosis in the CNS and with neurodegeneration [11, 12]. Increased TNF levels have been associated with neuropathology in animal models of sleeping sickness, a human disease induced by infection with the extracellular parasite sp. [13C15]. Indeed, TNF dysregulation has been associated with blood-brain barrier abnormalities and the initiation of CNS inflammation and pathology in non-infectious and infectious diseases [16]. Grapiprant (CJ-023423) However, the effect of TNF in the CNS during infection is unclear. This intracellular protozoan parasite is the etiologic agent of Chagas disease, a neglected tropical disease characterized by a systemic inflammatory response enriched in TNF in chronic patients [17, 18] and experimental models [19]. In the acute phase of infection, particularly in infants and susceptible experimental mice, intense meningoencephalitis and accumulation of amastigote forms of the parasite inside glial cells are common, but CNS inflammation and parasitism are drastically reduced in the chronic phase [20C29]. Nevertheless, in chronic infection, neurological involvement is observed in 75C90% of human immunodeficiency virus (HIV)-coinfected patients and in individuals immunocompromised by cancer, suppressive treatment, organ transplantation, or malnourishment [30, 31]. In these situations, the most common findings are neurological abnormalities, recrudescence of parasitemia, and parasite Grapiprant (CJ-023423) detection in the brain tissue and cerebrospinal POLD1 fluid [21, 24, 30]. In early diagnosed patients, the signs of CNS impairment disappear after treatment with the trypanocidal drug benznidazole [22C24]. In chronically infected individuals, reactivation of CNS parasitism may occur via the re-entry of blood circulating parasites; CNS invasion by inflammatory cells carrying parasite, likewise the macrophages carrying HIV by a Trojan horse mechanism [32]; or increase of low-grade CNS parasitism. In chronically persistence in Grapiprant (CJ-023423) the CNS cells remain unclear. Recently, we showed that in chronically infected C3H/He mice, most infection is increased by IFN, and the anti-TNF antibody infliximab abolished this IFN-induced effect. Therefore, IFN-stimulated.