Preserving Vascular Integrity Protects Mice against Multidrug-Resistant Gram-Negative Bacterial Infection

Area of Science:

• Microbiology
• Immunology
• Pharmacology

Background:

• Multidrug-resistant (MDR) organisms, particularly Gram-negative bacteria (GNB), pose a significant global health threat, leading to untreatable infections like pneumonia, ARDS, and sepsis.
• High-priority MDR pathogens identified by WHO and NIH include *Acinetobacter baumannii*, *Pseudomonas aeruginosa*, and carbapenemase-producing *Klebsiella pneumoniae* (CPKP).
• Current therapeutic strategies are challenged by the rapid emergence of antimicrobial resistance.

Purpose of the Study:

• To investigate the potential of targeting host vasculature, specifically the small GTPase ADP-ribosylation factor 6 (ARF6), as a therapeutic strategy against MDR GNB infections.
• To determine if genetic deletion or pharmacological inhibition of ARF6 can enhance survival rates in a murine model of GNB pneumonia.
• To elucidate the mechanism by which ARF6 inhibition confers protection against GNB-induced sepsis and vascular disruption.

Main Methods:

• Genetic deletion and pharmacological inhibition of ARF6 in mouse models.
• Infection of mice with MDR GNB, including *A. baumannii*, *P. aeruginosa*, and CPKP.
• Assessment of survival rates and mechanistic studies involving vascular integrity and signaling pathways (TLR4/MyD88/ARNO/ARF6).

Main Results:

• Genetic deletion or pharmacological inhibition of ARF6 significantly increased survival rates in mice infected with *A. baumannii*, *P. aeruginosa*, and CPKP.
• Pharmacological inhibition of ARF6 mimicked the protective effects of endothelium-specific *Arf6* disruption, confirming the on-target action.
• The protective mechanism involves the restoration of vascular integrity, which is compromised by GNB lipopolysaccharide (LPS) activation of the TLR4/MyD88/ARNO/ARF6 pathway.

Conclusions:

• Stabilizing host vasculature by targeting ARF6 represents a promising therapeutic strategy against infections caused by MDR GNB.
• This host-directed approach circumvents the issue of microbial drug resistance.
• Small-molecule inhibitors of ARF6 activation offer a potential alternative or adjunctive treatment for emerging and reemerging infectious diseases.