Figure 1.

Sensor and effector function of neonatal innate immune system to Staphylococci spp. (1) Monocytes detect Staphylococci through TLR2 and (2) result in TLR-mediated production of proinflammatory cytokines such as TNF, and (3) TNF activates neutrophils to produce oxygen radicals and release APPs. (4) Both endogenous plasma and Staphylococcus-derived adenosine inhibit pro-inflammatory innate immune responses. Newborn monocytes are deficient in MyD88, activation of MAP kinases, and in TLR-mediated TNF but do produce robust amounts of IL-6, a proresolution cytokine that inhibits neutrophil migration. Overall, this pattern of response impairs neutrophil activation and migration and secretion of APPs. Deficiencies in neonatal responses to staphylococci are depicted by smaller font size, whereas agents that are elevated in newborns are indicated with a larger and bolded font.