AUTHOR=Vivarini Áislan de Carvalho , Calegari-Silva Teresa Cristina , Saliba Alessandra Mattos , Boaventura Viviane Sampaio , França-Costa Jaqueline , Khouri Ricardo , Dierckx Tim , Dias-Teixeira Karina Luiza , Fasel Nicolas , Barral Aldina Maria Prado , Borges Valéria Matos , Van Weyenbergh Johan , Lopes Ulisses Gazos 

TITLE=Systems Approach Reveals Nuclear Factor Erythroid 2-Related Factor 2/Protein Kinase R Crosstalk in Human Cutaneous Leishmaniasis

JOURNAL=Frontiers in Immunology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2017.01127

DOI=10.3389/fimmu.2017.01127

ISSN=1664-3224

ABSTRACT=<p><italic>Leishmania</italic> parasites infect macrophages, causing a wide spectrum of human diseases, from cutaneous to visceral forms. In search of novel therapeutic targets, we performed comprehensive <italic>in vitro</italic> and <italic>ex vivo</italic> mapping of the signaling pathways upstream and downstream of antioxidant transcription factor [nuclear factor erythroid 2-related factor 2 (Nrf2)] in cutaneous leishmaniasis (CL), by combining functional assays in human and murine macrophages with a systems biology analysis of <italic>in situ</italic> (skin biopsies) CL patient samples. First, we show the PKR pathway controls the expression and activation of Nrf2 in <italic>Leishmania amazonensis</italic> infection <italic>in vitro</italic>. Nrf2 activation also required PI3K/Akt signaling and autophagy mechanisms. Nrf2- or PKR/Akt-deficient macrophages exhibited increased levels of ROS/RNS and reduced expression of <italic>Sod1</italic> Nrf2-dependent gene and reduced parasite load. <italic>L. amazonensis</italic> counteracted the Nrf2 inhibitor Keap1 through the upregulation of p62 <italic>via</italic> PKR. This Nrf2/Keap1 observation was confirmed <italic>in situ</italic> in skin biopsies from <italic>Leishmania</italic>-infected patients. Next, we explored the <italic>ex vivo</italic> transcriptome in CL patients, as compared to healthy controls. We found the antioxidant response element/Nrf2 signaling pathway was significantly upregulated in CL, including downstream target p62. <italic>In silico</italic> enrichment analysis confirmed upstream signaling by interferon and PI3K/Akt, and validated our <italic>in vitro</italic> findings. Our integrated <italic>in vitro, ex vivo</italic>, and <italic>in silico</italic> approach establish Nrf2 as a central player in human cutaneous leishmaniasis and reveal Nrf2/PKR crosstalk and PI3K/Akt pathways as potential therapeutic targets.</p>