Our body surface, skin, intestines and lungs are colonized by countless bacteria, fungi, and viruses, known as the microbiome, which composition makes a decisive contribution to human health and disease. However, the reason behind inflammations occurring in microbiome is mostly unknown. A recent study published in Cell has interpreted a mechanism by which specific intestinal microbiota amplifies inflammatory reactions in the lungs.
'The fungus Candida albicans, which colonizes the intestines, skin and mucous membranes, is actually harmless', Cornely said. 'However, our study has shown that Candida albicans affects the balance of our immune system.'
Candida albicans stimulates the immune system to produce specific defense cells, so-called Th17 cells. However, some of these Th17 cells then attack other fungi, such as Aspergillus fumigatus. This phenomenon is called cross-reactivity. The research showed that immune-compromised individuals have an increased level of cross-reactive Th17 cells in their lung tissue. This concentration is associated with a deterioration of these patients' health. The protective Th17 reaction in the intestine seems to amplify pathogenic immune processes in the lungs.
Deciphering such specific effects of individual microbes will in future contribute to the development of targeted therapies.