Brucella abortus Triggers a cGAS-Independent STING Pathway To Induce Host Protection That Involves Guanylate-Binding...

Area of Science:

• Immunology
• Microbiology
• Cell Biology

Background:

• Innate immunity relies on pattern recognition receptors to detect microbial components.
• Brucella abortus DNA triggers signaling via TLR9, AIM2, and STING.
• Type I IFNs and GBPs are key antiviral and antibacterial effectors.

Purpose of the Study:

• To investigate the role of STING in Brucella infection immunity.
• To elucidate the mechanisms of STING-mediated host defense.
• To determine the interplay between STING, cGAS, GBPs, and AIM2 in Brucella control.

Main Methods:

• Microarray analysis of STING knockout macrophages infected with Brucella.
• Assessment of IL-1β secretion, caspase-1 activation, and GBP expression.
• In vivo studies using STING, cGAS, GBP, and AIM2 knockout mice.
• Small interfering RNA (siRNA) mediated knockdown experiments.

Main Results:

• STING deficiency downregulated type I IFN-associated genes (IFN-β, GBPs) in Brucella-infected macrophages.
• STING, but not cGAS, was essential for IL-1β secretion, caspase-1 activation, and GBP2/3 expression.
• STING was critical for host protection against Brucella in vitro and in vivo.
• GBPchr3 knockout mice showed increased susceptibility to Brucella infection.
• Brucella DNA colocalized with AIM2, and AIM2 deficiency impaired host resistance.

Conclusions:

• STING mediates Brucella control through a cGAS-independent pathway involving type I IFNs and GBPs.
• STING signaling facilitates GBP-mediated release of Brucella DNA into the cytosol, activating AIM2.
• This pathway is crucial for limiting intracellular bacterial replication and promoting host survival.