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Updated: Dec 21, 2025
Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature
Published on: April 1, 2014
Preserving Vascular Integrity Protects Mice against Multidrug-Resistant Gram-Negative Bacterial Infection
Teclegiorgis Gebremariam1, Lina Zhang1,2, Sondus Alkhazraji1
1The Lundquist Institute for Biomedical Innovations at Harbor-University of California Los Angeles (UCLA) Medical Center, Torrance, California, USA.
Abstract:
The rise in multidrug-resistant (MDR) organisms portends a serious global threat to the health care 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's and National Institutes of Health's high-priority MDR pathogens for targeted development of new therapies. Here, we show that stabilizing the host's 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, and CPKP. We show that the pharmacological inhibition of ARF6-GTP phenocopies endothelium-specific Arf6 disruption in enhancing the 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 acts by the restoration of vascular integrity disrupted by GNB lipopolysaccharide (LPS) activation of the TLR4/MyD88/ARNO/ARF6 pathway. By targeting the host's vasculature with small-molecule inhibitors of ARF6 activation, we circumvent microbial drug resistance and provide a potential alternative/adjunctive treatment for emerging and reemerging pathogens.
Insights
Targeting host vasculature by inhibiting ADP-ribosylation factor 6 (ARF6) improves survival in mice infected with multidrug-resistant Gram-negative bacteria. This approach bypasses microbial resistance, offering a potential new treatment for severe infections.
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.
