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

The rise in multidrug resistant (MDR) organisms portends a serious global threat to the healthcare system with nearly untreatable infectious diseases, including pneumonia and its often fatal sequelae, acute respiratory distress syndrome (ARDS) and sepsis. Gram-negative bacteria (GNB) including Acinetobacter baumannii, Pseudomonas aeruginosa, and carbapenemase-producing Klebsiella pneumoniae (CPKP), are among the World Health Organization and National Institutes of Healths high priority MDR pathogens for targeted development of new therapies. Here we show that stabilizing the hosts vasculature by genetic deletion or pharmacological inhibition of the small GTPase ADP-ribosylation factor 6 (ARF6) increases survival rates of mice infected with A. baumannii, P. aeruginosa, CPKP pneumonia. We show that pharmacological inhibition of ARF6-GTP phenocopies endothelial-specific Arf6 disruption in enhancing survival of mice with A. baumannii pneumonia, suggesting that inhibition is on target. Finally, we show that the mechanism of protection elicited by these small molecule inhibitors is by restoration of vascular integrity disrupted by GNB lipopolysaccharide (LPS) activation of TLR4/MyD88/ARNO/ARF6 pathway. By targeting the hosts vasculature with small molecule inhibitors of ARF6 activation, we circumvent microbial drug resistance and provide a potential alternative/adjunctive treatment for emerging and re-emerging pathogens.