Infections involving Candida biofilms: is the solution in lichens ? – LICSYFILM

The biofilm mode for survival and growth of microorganisms is now seen as a serious threat to public health. The American National Institute of Health (NIH) currently estimates that biofilms account for over 80% of all human infections. Due to their ubiquitous nature, biofilms are difficult to eradicate. In our society, the increased use of medical implant devices is a reality. Devices such as stents, shunts, prostheses, implants, endotracheal tubes, pacemakers, and various types of catheters, to name a few, have all been shown to support colonization and biofilm formation. Cells within a biofilm structure (bacteria or fungi) show a reduced susceptibility to specific commonly used antimicrobial and, in addition, such cells are less susceptible to our immune system. Fungi most commonly associated with such disease episodes are in the Genus Candida, most notably Candida albicans, which causes both superficial and systemic disease. Invasive candidiasis led to a mortality rate in patient of 40%. Consequently, new strategies for the prevention or treatment of biofilm formation are necessary.
Lichens are symbiotic organisms resulting from the association of a fungus and an algae or a cyanobacteria. Recently, it has been shown that lichen thallus is constituted by more than three partners. Thus, basidiomycetes yeast, ascomycetes fungi or bacteria are present inside or outside the lichen thallus. This microbial community, organized in a biofilm-like manner, develops interactions and biosynthesize active metabolites for their survival and development.
To demonstrate competition between biofilms and lichens, and to find new therapeutic anti-biofilm compounds, an original project has been recently initiated. In response to the global objectives of societal challenge n°4, health and wellness challenge, the aim of this project is to explore the potency of lichens, and their associated fungal flora (endolichenic fungi) to fight Candida biofilms. The expertise of the scientific coordinator completed with the involvement of several chemists and phytochemists inside the team, as well as researchers specialized in fungal biofilms, is the key of this multidisciplinary project. The work plan is divided in five main steps. The first one is the access to a wide diversity of extracts issued from the endolichenic lichen flora in order to complete the existing lichen extracts library. The second one is the isolation of compounds from selected lichens and fungi. The third one is the increase of the number of active compounds by doing pharmacomodulations. Extracts and isolated metabolites will be evaluated in vitro against C. albicans biofilms (against maturation phase and already-formed biofilms). For the most active compounds, the non-specificity of the activity will be checked using several clinical isolates of C. albicans and additional microscopic analyses will be performed. The final step will consist in the in vivo evaluation of non-cytotoxic compounds on a mice catheter model.