Skin and mucosal surfaces of animals and man are covered with myriads of microbes that create complex ecosystems with their host. The constant exposure of the host to microbes shapes the immune reactivity of the host locally and at distant sites, and it even influences seemingly unrelated processes ranging from digestion to behavior. Perturbations that disrupt the equilibrium of the microbial ecosystem may lead to the overgrowth of species with pathogenic potential, and in turn to the development of disease. Moreover, microbe-specific immune reactivity bears the potential to promote inflammation and immunopathology. Therefore, tight regulation of the microbiota-host interplay is of outmost importance.
Fungi are now recognized as common members of the microbiota on nearly all epithelial surfaces, and recent examples revealed that - similarly to their bacterial counterparts - commensal fungal communities might have an important role in host physiology and immunity. Two of the most abundant members of the fungal microbiome are the yeasts Candida, which colonizes diverse mucosal epithelia, and Malassezia, which is abundant on the skin.
Research in the LeibundGut-lab focuses on the immune mechanisms that regulate fungal commensalism in barrier tissues and prevent fungal overgrowth and disease but may also have host adverse consequences under some conditions. We developed in vivo and in vitro experimental systems to model the intricate interactions between fungi and host under diverse physiologically relevant conditions. Specific projects focus on
- Protective immunity against Candida albicans in the oral mucosa and systemically
- Cutaneous immune mechanisms against the abundant skin commensal yeast Malassezia
- Immunopathological consequences of immune reactivity against fungal commensals (e.g. skin allergic disorders)
- Pathogenicity mechanisms of Candida albicans and Malassezia
ON THE RELEVANCE OF FUNGAL INFECTIONS:
Although fungi live as normal members of the microbiota on the skin and mucosa of all healthy individuals, they can also cause disease if host defenses are breached.
Fungal diseases are neglected worldwide, despite the fact that they affect billions of people annually. Nearly 4 billion of people have a fungal infection of the skin, the fourth most common on earth. Several millions of people develop severe systemic infections with fungi that are life threatening. In fact, fungal infections now kill more people worldwide than malaria and similar numbers to tuberculosis. Moreover, fungi are also implicated in common inflammatory disorders such as atopic dermatitis, asthma and inflammatory bowel disease.
There are important deficiencies in diagnostics and treatments of fungal diseases and there is no effective vaccine against fungal infections. More research is needed for a better understanding of fungal pathogenesis and antifungal immunity.
Initiatives have recently been launched with the aim of raising awareness of fungal infections and the risk they pose. More details can be found here:
Global Action Fund for Fungal Infections https://www.gaffi.org/
Fungal Diseases – Centres for Disease Control and Prevention https://www.cdc.gov/fungal/
MRC Centre for Medical Mycology https://www.exeter.ac.uk/doctoralcollege/funding/fundedcentres/mrccmm/