Intracellular pathogens are considered to be among the major bacterial public health threats. The outcome of intracellular infections is largely due to the ability of pathogens to utilize specific cell receptors and host components for invading and subverting cellular activities. When pathogens localize intracellularly, they receive protection both from the host defense system and from a variety of antimicrobials. Despite the ability of certain antibiotics to cross cell membrane, their intracellular efficacy can be poor due to: (I) intracellular concentrations below the minimum inhibitory value; (II) intracellular environment (e.g., acidic pH) that may affect the antibiotic activity; (III) antibiotic accumulation in subcellular compartments that are different from those in which pathogens reside. In short, the development of more effective treatments, but also with less side effects, is urgent. Herein, it is proposed to tackle this through Trojan horse nanoparticles designed I) to target infected phagocytic (i.e. macrophages) or non-phagocytic (i.e. keratinocytes) cells and II) to deliver antimicrobials at the sub-cellular level, both for obligate (i.e. Mycobacterium tuberculosis) and facultative (i.e. Staphylococcus aureus) intracellular pathogens.
In short, this proposal would be formed by:
Milestone 1 (four months): Molecular profiling (cytokine production, integrins and CD44 expression) of infected macrophages or keratinocytes/three pathogens.
Milestone 2 (three months): Kinetics of uptake and intracellular trafficking of HA-based nanoparticles in infected macrophages or keratinocytes.
Milestone 3 (five months): Efficacy of the antimicrobials-loaded HA-based nanoparticles against the intracellular pathogens and their potential toxicity against cells.
The strength points of the project are that A) nanoparticles that specifically bind to CD44 can preferentially target host cells (i.e. activated macrophages, keratinocytes); B) nanoparticles that especially accumulate in lysosomes can target to certain pathogens (i.e. M. tuberculosis, S. aureus) and deliver antimicrobials at the sub-cellular level (lysosomes); C) this will facilitate the development of efficacious therapies with minimal doses of antibiotics; D) by broadening the therapeutic window of existing antibiotics, such therapies will be advantageous also against `naturally¿ antibiotic-resistant pathogens, such as M. tuberculosis and S. aureus.
The successful completion of the present project will provide the basis for a novel research based on a targeted antimicrobial therapy to infected cells. The main goal will be to develop novel, smart and more effective antimicrobial-loaded nano-vectors. After two years in the United Kingdom (Laboratory of Polymers and Biomaterials of Prof. Tirelli, University of Manchester), three months in France (European Molecular Biology Organization short-fellow award, Bichat Hospital, Paris) and long-running experience (15 papers in almost six years) with nano-carriers and their interactions with cells, i fill confident to investigate and develop a novel scientific research in this field.