Head:	Loris Rizzello (Associate Professor)
Team Members:	Edoardo Scarpa (Post-Doctoral Research) Anna Griego (Post-Doctoral Fellow) Andrea Fumagalli (Scholarship holder) Giulia Antinori (M. Sc. Student) Arti Sharma (M. Sc. Student) Beatrice Antinori (B.S. Student)
Website:	https://infectiondynamics.unimi.it/

  

GENERAL DESCRIPTION

The infectious diseases for which vaccination and antimicrobial therapies have been particularly successful are those caused by extracellular pathogens, i.e. bacteria that spend a significant part of their life cycle outside the host cell. Conversely, vaccines and antibiotics against intracellular pathogens - bacteria that evolved to invade, colonize and replicate within host cells - have proven to be much more difficult to develop.
Our Infection Dynamics Unit proposes a research vision that aims to revolutionize the way we treat infections caused by intracellular pathogens, with the aim of finding a universal therapy for infectious diseases that also contrasts the development of drug resistance. Our particular interest is the eradication of human tuberculosis, one of the worst human pandemics, but the ultimate goal is to create a universal delivery system that recognizes any infected cell. To do this, we will first examine the molecular "bar codes" of infected cells, i.e. those specific membrane proteins that cells express at the time of infection. This information is essential to then engineer a repertoire of super-selective polymeric nanoparticles, known as Polymersomes, functionalized with selective ligands capable of recognizing, binding and attacking only infected cells, leaving uninfected cells completely intact.

RESEARCH TOPICS

1. Biochemical analysis and high-resolution confocal live-imaging of host-pathogen interactions.

In this section we will perform a massive phenotypic screening of macrophages infected with Mycobacterium tuberculosis to decode the receptors related to the infection (i.e., the Pathogens Recognition Receptors - PRR). This will allow the study of host-pathogen interactions to be placed in the equation for the discovery of new antibacterial drugs. To pursue this goal, we will use a Phage Display approach in which libraries of T7 bacteriophages will be incubated with infected macrophages, a process defined as "biopanning". After biopanning, strongly adherent phages will be recovered and sequenced (NGS) and specific peptide ligands that bind infected cells will be identified. This will also allow the differential regulation of PPR, depending on the presence (or not) of intracellular pathogens. The dynamics of infection will also be followed with high resolution confocal imaging techniques, where fluorescent pathogens will be used, and the specific intracellular localization will be analyzed. This will allow us to understand how fundamental molecules for virulence and pathogenesis are distributed within the host over time.

2. Design of new nanotechnological tools to eliminate bacterial drug resistance.

This line of research aims to design and develop super-selective polymeric nanovesicles specifically aimed at recognizing and targeting only infected cells. The polymeric nanoparticles, called polymersomes, will in fact be decorated with the ligand peptides discovered by the phage display biopanning. For this project, the best candidate for polymers will be based on the PEG-PDPA di-block, where PEG is poly (ethylene glycol) and PDPA is poly (2- (diisopropylamino) ethyl methacrylate). This copolymer self-assembles in water and creates vesicles with an aqueous lumen where drugs can be loaded. The PEG allows an easy functionalization of the ligand peptides avoiding the protein opsonization (giving the polymers a long circulation time and a low non-specific bond). PDPA, on the other hand, is a block that triggers the disassembly of polymers at pH values below 6.4, typical of endocytosis in the initial phase. Sensitivity to pH will allow the loaded drug to be released into the cell cytosol after internalization. This combined approach of high specificity in targeting only the cells of interest, combined with a very high intracellular drug release, will allow to eradicate pathogens and avoid the onset of drug resistance due to the constant use of doses in sub-effective concentration.

MAIN COLLABORATORS:

• Prof. Giuseppe Battaglia. University College London, Department of Chemistry
• Prof. Timothy McHugh. University College London, Division of Infection and Immunity
• Prof. Riccardo Manganelli. Università degli Studi di Padova
• Prof.ssa Marilina Pasca. Università degli Studi di Pavia
• Prof. Giorgio Volpe. University College London, Department of Chemistry
• Dr. Alessandro Poma. University College London, Division of Biomaterials and Tissue Engineering
• Dr. Alessandro Gori. CNR