Commensal Fungi Recapitulate the Protective Benefits of Intestinal Bacteria

• Published in: Cell host & microbe Vol. 22; no. 6; pp. 809 - 816.e4
• Main Authors: Jiang, Tony T., Shao, Tzu-Yu, Ang, W.X. Gladys, Kinder, Jeremy M., Turner, Lucien H., Pham, Giang, Whitt, Jordan, Alenghat, Theresa, Way, Sing Sing
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 13-12-2017
• Subjects: Animals; Candida albicans; Colitis - prevention & control; commensal microbes; dextran sodium sulfate; Disease Resistance; fungal immunity; Fungi - growth & development; Fungi - immunology; Gastrointestinal Microbiome; Immunity, Cellular; Immunity, Innate; influenza A virus; mannans; Mice; Orthomyxoviridae Infections - prevention & control; Saccharomyces cerevisiae; Symbiosis; Candida albicans; fungal immunity; dextran sodium sulfate; mannans; Saccharomyces cerevisiae; commensal microbes; influenza A virus
• ISSN: 1931-3128; 1934-6069
• DOI: 10.1016/j.chom.2017.10.013

Commensal intestinal microbes are collectively beneficial in preventing local tissue injury and augmenting systemic antimicrobial immunity. However, given the near-exclusive focus on bacterial species in establishing these protective benefits, the contributions of other types of commensal microbes remain poorly defined. Here, we show that commensal fungi can functionally replace intestinal bacteria by conferring protection against injury to mucosal tissues and positively calibrating the responsiveness of circulating immune cells. Susceptibility to colitis and influenza A virus infection occurring upon commensal bacteria eradication is efficiently overturned by mono-colonization with either Candida albicans or Saccharomyces cerevisiae. The protective benefits of commensal fungi are mediated by mannans, a highly conserved component of fungal cell walls, since intestinal stimulation with this moiety alone overrides disease susceptibility in mice depleted of commensal bacteria. Thus, commensal enteric fungi safeguard local and systemic immunity by providing tonic microbial stimulation that can functionally replace intestinal bacteria.
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•Commensal fungi functionally replace intestinal bacteria in mitigating tissue injury•Commensal fungi positively calibrate the activation of protective CD8 T cells•Protective benefits of commensal fungi require persistent intestinal colonization•Fungal cell-wall mannans recapitulate the protective benefits of commensal fungi
Intestinal colonization is not restricted to bacteria alone, but includes fungi whose symbiotic interactions with the mammalian host remain incompletely defined. Jiang et al. demonstrate that diverse species of fungi can functionally replace enteric bacteria by conferring protection against infectious and inflammatory disorders.