Differential production of Type I IFN determines the reciprocal levels of IL-10 and proinflammatory cytokines produced by C57BL/6 and BALB/c macrophages

Pattern recognition receptors (PRR) detect microbial products and induce cytokines which shape the immunological response. Interleukin-12 (IL-12), tumor necrosis factor alpha (TNF-) and IL-1 are proinflammatory cytokines which can be essential for resistance against infection, but if produced at high levels, may contribute to immunopathology. In contrast, IL-10 is an immunosuppressive cytokine which dampens proinflammatory responses, but can also lead to defective pathogen clearance. The regulation of these cytokines is therefore central to the generation of an effective but balanced immune response. Here, we show that macrophages derived from C57BL/6 mice produce low levels of IL-12, TNF- and IL-1, but high levels of IL-10 in response to TLR4 and TLR2 ligands LPS and PamCSK4, and Burkholderia pseudomallei a Gram-negative bacterium which activates TLR 2/4. In contrast, macrophages derived from BALB/c mice show a reciprocal pattern of cytokine production. Differential production of IL-10 in B. pseudomallei and LPS stimulated C57BL/6 and BALB/c macrophages was due to a type I IFN dependent, but IL-27 independent mechanism. Further, type I IFN contributed to differential IL-1 and IL-12 production in B. pseudomallei and LPS stimulated C57BL/6 and BALB/c macrophages, via both IL-10-dependent and independent mechanisms. These findings highlight key pathways responsible for the regulation of pro- and anti-inflammatory cytokines in macrophages and reveal how they may differ according to the genetic background of the host.

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Howes A, Taubert C, Blankley S, Spink N, Wu X, Graham CM, Zhao J, Saraiva M, Ricciardi-Castagnoli P, Bancroft GJ, O'Garra A