Deehan, R. | Search bioRxiv

bioRxiv2024

Rational Design of Frontline Institutional Phage Cocktail for the Treatment of Nosocomial Enterobacter cloacae Complex Infections

Phage therapy is a promising strategy to treat antimicrobial-resistant infections. Currently, phage therapy applications span personalised treatments that are tailored for a given patients infection, through to the use of pre-established cocktails of virulent phages against clinically relevant pathogens. However, both approaches face challenges, with personalised phage therapy being time-consuming and requiring a phage match to a patients infection, while phage cocktails may not be effective against a patients specific strain. The Alfred Hospital in Melbourne, Australia has reported an ongoing outbreak of infections by the Enterobacter cloacae complex (ECC), a group of emerging multidrug-resistant pathogens responsible for considerable morbidity and mortality. Utilising the hospitals strain collection, built over the last decade, we established an initial three-phage product with 54% ECC coverage that effectively reduced bacterial loads (>99%) in septicaemic mice. We then iteratively improved this product by enhancing phage killing efficiency using phage training and expanded host range through targeted phage isolation against low-coverage ECC strains. This iterative optimisation led to the creation of the product Entelli-02, containing five well characterised virulent phages that target clinical ECC strains through distinct bacterial cell surface receptors. Importantly, Entelli-02 exhibits broad host coverage (99%) and efficacy (92%) against The Alfred Hospitals ECC strain collection (n = 156). We produced this as a therapeutic-grade product, verified and endotoxin unit compliant, ready for use. This approach integrated academic phage research with clinical insights to produce the phage product Entelli-02 as an institution-specific phage cocktail with frontline efficacy and on-demand availability. SUMMARYO_ST_ABSIn briefC_ST_ABSWe developed a phage product containing five phages with frontline potential to address infections caused by multidrug-resistant Enterobacter cloacae complex.

microbiology↗

bioRxiv2023

Spermidine suppresses DC activation via eIF5A hypusination and metabolic adaptation

Cell metabolism plays an important role in immune effector responses and through responding to metabolic signals, immune cells can adapt and regulate their function. Arginine metabolism in Dendritic cells (DC) has been shown to reduce T cell activation; however, it is unclear how this immunosuppressive state is induced. To address this issue, we examined the immunomodulatory capacity of various metabolites from arginine metabolism. Through the use of a recently described DC:T cell interaction assay and flow cytometry we demonstrated that spermidine most significantly inhibited DC activation, preventing subsequent interactions with CD4 T cells. DC function could be restored by addition of inhibitors of spermidine metabolism via the eIF5A-hypusine axis, required for expression of some mitochondrial enzymes. We also demonstrated that the spermidine induced-immunosuppressive state protected DC against activation induced loss of mitochondrial capacity for energy generation, which was also hypusination dependent. Taken together this data demonstrates that spermidine is the key immunomodulatory component downstream of arginine metabolism and that it mediates this effect by stimulating hypusination-dependent protection of OXPHOS in DC, which in turn results in a reduced ability of DC to activate and interact with T cells. This pathway may be utilised by the immune system to regulate excessive immune responses but could also be exploited by pathogens as a method of immune evasion.

immunology↗