RAGE-mediated suppression of IL-10 results in enhanced mortality in a murine model of Acinetobacter baumannii sepsis.

The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor capable of recognizing multiple pathogen-associated and danger-associated molecular patterns that contributes to the initiation and potentiation of inflammation in many disease processes. During infection, RAGE functions to either exacerbate disease severity or enhance pathogen clearance depending on the pathogen studied. Acinetobacter baumannii is an opportunistic human pathogen capable of causing severe infections, including pneumonia and sepsis, in impaired hosts. The role of RAGE signaling in response to opportunistic bacterial infections is largely unknown. In murine models of A. baumannii pneumonia, RAGE signaling alters neither inflammation nor bacterial clearance. In contrast, RAGE(-/-) mice systemically infected with A. baumannii exhibit increased survival and reduced bacterial burdens in the liver and spleen. The increased survival of RAGE(-/-) mice is associated with increased circulating levels of the anti-inflammatory cytokine, IL-10. Neutralization of IL-10 in RAGE(-/-) mice results in decreased survival during systemic A. baumannii infection that mirrors that of WT mice, and exogenous IL-10 administration to WT mice enhances survival in this model. These findings demonstrate the role for RAGE-dependent IL-10 suppression as a key modulator of mortality from Gram-negative sepsis.