Functional high-throughput analysis of the role of microRNAs in regulating Staphylococcus aureus infection

Project Information

miRs4Staph

Grant agreement ID: 893942

DOI

10.3030/893942

Project closed

EC signature date 24 March 2020

Start date 15 October 2020

End date 14 October 2022

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 147 815,04

EU contribution

€ 147 815,04

Coordinated by

CENTRO DE NEUROCIENCIAS E BIOLOGIACELULAR ASSOCIACAO
Portugal

Periodic Reporting for period 1 - miRs4Staph (Functional high-throughput analysis of the role of microRNAs in regulating Staphylococcus aureus infection)

Reporting period: 2020-10-15 to 2022-10-14

Summary of the context and overall objectives of the project

Staphylococcus aureus is a bacterium commonly found on the skin and nares of both humans and animals. However, it can become an opportunistic pathogen, causing a variety of clinical manifestations, from minor skin infections to life-threatening diseases, including pneumonia, osteomyelitis and endocarditis. The treatment of S. aureus infections has become increasingly difficult due to the emergence of antibiotic-resistant strains in clinical context and the spreading of these strains in the community.
Nowadays, it is known that S. aureus can live inside host cells and this intracellular lifestyle is crucial for infection dissemination and persistence. Also, intracellular bacteria may be protected from the activity of antimicrobials, leading to treatment failure and post-therapy relapse. In order to successfully invade and survive inside host cells, S. aureus needs to modulate host cell functions through several mechanisms. MiRNAs are small molecules present in host cells, which are capable of regulating cellular gene expression and, thus, influence the outcome of S. aureus infection.
In this context, the goal of this study was to discover miRNAs that regulate S. aureus invasion, survival, and replication within host cells. The knowledge of these factors may potentially reveal novel therapeutical targets to control S. aureus infection.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

To discover host cell factors involved in S. aureus – host interplay, we used an in vitro S. aureus infection model, in which the effect of 2,042 individual miRNAs was evaluated in S. aureus infection of human epithelial cells. For that, we used innovative cell and molecular biology technologies, including high-throughput screening coupled to automated microscopy. As a result, we identified 87 miRNAs that strongly increased or decreased S. aureus infection and replication.
To increase the biological/clinical relevance of our findings, we validated the effect of this subset of 87 miRNAs on infection by S. aureus clinical isolates obtained from patients with different clinical manifestations, namely bone/joint infections, infective endocarditis and bacteraemia. We observed a strong conservation of the effect of the selected miRNAs on the infection and replication of the tested S. aureus isolates. We also performed time course experiments to determine which stages of S. aureus infection cycle were affected by specific miRNAs, and discovered that both the invasion and replication of S. aureus were regulated.
We have now selected two miRNAs that increase intracellular replication of S. aureus for detailed characterization, which is underway.
The results were presented by the Fellow at several advanced courses, meetings and conferences. An article describing the characterization of S. aureus intracellular lifestyles has been published, and additional manuscripts are expected. The Fellow participated in outreach activities, namely in the European Researcher’s Night.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

This study is revealing novel host molecular players that are important for S. aureus infection, which could be explored for the development of novel therapeutic approaches. This is particularly relevant at a time when antibiotic resistance is a major global health concern. In fact, the latest studies indicate that 4.95 million deaths worldwide were associated with infections caused by antimicrobial resistant bacteria in 2019. Among them, S. aureus is one of the most problematic multi-drug resistant pathogens, being the second most common cause of global deaths associated with bacterial antimicrobial resistance.
Therefore, the knowledge acquired from this project on host mechanisms relevant for S. aureus infection may reveal novel targets for therapeutic intervention and thus lead to the development of novel antimicrobial therapies based on host targets rather than aiming at the pathogen, which has high capacity of acquiring antibiotic resistance.

schematic representation of the project