FIG. 3.

H₂O₂-induced responses in the host cell. Spn produces large amounts of H₂O₂, which induce a plethora of host cell responses. This includes oxidative and ER stress (red), activation of all three MAPK subfamilies (green), translocation of NF-κB-complex into the nucleus (violet), and inflammasome inhibition (blue). Oxidative stress leads to production of mtROS and release of mtDNA and subsequent STING-dependent type I IFN (IFN-β) expression. Translocation of NF-κB-complex into the nucleus leads to expression of proinflammatory chemokines and cytokines (such as IL-8 and IL23a) and H₂O₂-dependent production of Nrf-2, which induces expression of HO-1. HO-1, heme oxygenase 1; IFN, interferon; IL, interleukin; MAPK, mitogen-activated protein kinase; mtDNA, mitochondrial DNA; mtROS, mitochondrial reactive oxygen species; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells; STING, stimulator of interferon genes. Color images are available online.