FIBCD1 Deficiency Decreases Disease Severity in a Murine Model of Invasive Pulmonary Aspergillosis

Aspergillus fumigatus is a ubiquitous mold associated with the development of pulmonary diseases that include invasive pulmonary aspergillosis (IPA), an often fatal opportunistic infection. FIBCD1 is a transmembrane endocytic membrane receptor widely expressed on human epithelium. Although FIBCD1 was previously shown to bind chitin, modulate fungal colonization of the gut, and inhibit intestinal inflammation, the role of FIBCD1 in the context of lung fungal infection remains unknown. In this study, we observed that mortality, fungal burden, and tissue histopathology were decreased in the absence of FIBCD1 in murine IPA. Quantitative RT-PCR analyses demonstrated decreased inflammatory cytokines in the lungs of neutrophil-depleted FIBCD1−/− mice with IPA, when compared with wild-type controls. In contrast, inflammatory cytokines were increased in immune-competent FIBCD1−/− mice after fungal aspiration, suggesting that the presence of neutrophils is associated with cytokine modulation. In contrast to the clear IPA phenotype, FIBCD1−/− mice with systemic infection or bleomycin-induced lung injury exhibited similar morbidity and mortality when compared with their wild-type counterparts. Thus, our study identifies a detrimental role of FIBCD1 in IPA. ImmunoHorizons, 2021, 5: 983–993.