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Autoimmunity and cystatin SA 1 deficiency behind chronic mucocutaneous candidiasis in autoimmune polyendocrine syndrome

Patients with the monogenic disease autoimmune polyendocrine syndrome type I (APS I) develop autoimmunity against multiple endocrine organs and suffer from chronic mucocutaneous candidiasis (CMC), a paradoxical complication with an unknown mechanism. We report that saliva from APS I patients with CMC was defective in inhibiting growth of C. albicans in vitro and had reduced levels of a salivary protein identified as cystatin SA1. In contrast, APS I patients with no CMC expressed salivary cystatin SA1 and could inhibit C. albicans to the same extent as healthy controls. We evaluated the anti-fungal activity of cystatin SA1 and found that synthesized full length cystatin SA1 efficiently inhibited growth of C. albicans in vitro. Moreover, APS I patients exhibited salivary IgA autoantibodies recognizing myosin-9, a protein expressed in the salivary glands that also produce cystatin SA1, thus linking autoimmunity to cystatin SA1 deficiency and CMC. This data suggests an autoimmune mechanism behind CMC in APS I and provide rationale for evaluating cystatin SA1 in antifungal therapy.

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Correspondence to Emma Lindh.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  • Salivary Gland
  • Full Length
  • Candidiasis
  • Antifungal Therapy
  • Unknown Mechanism