Modulation of the fungal mycobiome is regulated by the chitin-binding receptor FIBCD1.

Host-microbiota interactions are critical in regulating mammalian health and disease. In addition to bacteria, parasites, and viruses, beneficial communities of fungi (the mycobiome) are important modulators of immune- and tissue-homeostasis. Chitin is a major component of the fungal cell wall, and fibrinogen C containing domain 1 (FIBCD1) is a chitin-binding protein; however, the role of this molecule in influencing host-mycobiome interactions in vivo has never been examined. Here, we identify direct binding of FIBCD1 to intestinal-derived fungi and demonstrate that epithelial-specific expression of FIBCD1 results in significantly reduced fungal colonization and amelioration of fungal-driven intestinal inflammation. Collectively, these results identify FIBCD1 as a previously unrecognized microbial pattern recognition receptor through which intestinal epithelial cells can recognize and control fungal colonization, limit fungal dysbiosis, and dampen intestinal inflammation.