Nod1, Nod2 and Rip2 axis contributes to host immune defense against intracellular Acinetobacter baumannii infection

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Nod1, Nod2 and Rip2 axis contributes to host immune defense against intracellular Acinetobacter baumannii infection
Title:
Nod1, Nod2 and Rip2 axis contributes to host immune defense against intracellular Acinetobacter baumannii infection
Journal Title:
Infection and Immunity
Keywords:
Publication Date:
23 December 2013
Citation:
Abstract:
Acinetobacter baumannii is a major extensively drug-resistant lethal human nosocomial-bacterium. Yet, the host innate-immune mechanisms controlling A. baumannii are less understood. Although viewed as an extracellular-pathogen, A. baumannii can also invade and survive intracellularly. However, whether host innate-immune pathways sensing intracellular-bacteria contribute to immunity against A. baumannii is not known. Here, we provide evidence for the first time that intracellular anti-bacterial innate-immune receptors Nod1 and Nod2, and their adaptor Rip2, play critical roles in sensing and clearance of A. baumannii by human airway epithelial cells in vitro. A. baumannii infection up-regulated Rip2 expression. Silencing of Nod1, Nod2 and Rip2 expression profoundly increased intracellular invasion, and prolonged the multiplication and survival of A. baumannii in lung epithelial cells. Notably, the Nod1/2-Rip2 axis did not contribute to the control of A. baumannii infection of human macrophages, indicating that they play cell type specific roles. Nod1/2-Rip2 axis was needed for A.baumannii infection-induced activation of NF-κB, but not MAP kinases. Moreover, Nod1/2-Rip2 axis was critical to induce optimal cytokine and chemokine response to A. baumannii infection. Mechanistic studies showed that Nod1/2 pathway contributed to the innate control of A. baumannii infection through the production of β-defensin 2 by airway epithelial cells. This study revealed new insights into the immune control of A. baumannii, and may contribute to the development of effective immune therapeutics and vaccines against A. baumannii.
License type:
PublisherCopyrights
Funding Info:
Description:
ISSN:
0019-9567
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