IFNβ autocrine feedback is required to sustain TLR induced production of MCP-1 in macrophages.

Chemokines, including MCP-1, are crucial to mounting an effective immune response due to their ability to recruit other immune cells. We show that sustained LPS or poly(I:C)-stimulated MCP-1 production requires an IFNβ-mediated feedback loop. Consistent with this, exogenous IFNβ was able to induce MCP-1 transcription in the absence of other stimuli. Blocking IFNβ signaling with Ruxolitinib, a JAK inhibitor, inhibited MCP-1 transcription. The MCP-1 promoter contains potential STAT binding sites and we demonstrate that STAT1 is recruited upon IFNβ stimulation. Furthermore we find that IL-10 knockout increases MCP-1 production in response to LPS, which may reflect an ability of IL-10 to repress IFNβ production. Overall, these results show the importance of the balance between IFNβ and IL-10 in the regulation of MCP-1.