RT Journal Article SR Electronic(1) A1 Alothaimeen, Torki A1 Trus, Evan A1 Basta, Sameh A1 Gee, KatrinaYR 2021 T1 Differential TLR7-mediated cytokine expression by R848 in M-CSF- versus GM-CSF-derived macrophages after LCMV infection JF Journal of General Virology, VO 102 IS 3 OP SP 001541 DO https://doi.org/10.1099/jgv.0.001541 PB Microbiology Society, SN 1465-2099, AB Granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) play an important role in macrophage (MФ) development by influencing their differentiation and polarization. Our goal was to explore the difference between M-CSF- and GM-CSF-derived bone marrow MФ responsiveness to TLR7-mediated signalling pathways that influence cytokine production early after infection in a model of acute virus infection. To do so, we examined cytokine production and TLR7-mediated signalling at 1 h post-lymphocytic choriomeningitis virus (LCMV) Armstrong (ARM) infection. We found that R848-induced cytokine expression was enhanced in these cells, with GM-CSF cells exhibiting higher proinflammatory cytokine expression and M-CSF cells exhibiting higher anti-inflammatory cytokine expression. However, R848-mediated signalling molecule activation was diminished in LCMV-infected M-CSF and GM-CSF macrophages. Interestingly, we observed that TLR7 expression was maintained during LCMV infection of M-CSF and GM-CSF cells. Moreover, TLR7 expression was significantly higher in M-CSF cells compared to GM-CSF cells. Taken together, our data demonstrate that although LCMV restrains early TLR7-mediated signalling, it primes differentiated MФ to enhance expression of their respective cytokine profiles and maintains levels of TLR7 expression early after infection., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/jgv.0.001541