TNF and infection: After infection with viable intracellular pathogens, interaction with the adapter protein MyD88 leads to NFκB-dependent expression of Interleukin (IL)-6, IL-12, IL-27, tumor necrosis factor alpha (TNFα) and interferon (IFN) γ, thus promoting a Th1 response, as well as interferon response factor (IRF)-7- and IRF5-triggered production of type I IFNs (Figure 1 pathway a).