Integrin αXβ₂ is a leukocyte receptor for Candida albicans and is essential for protection against fungal infections

J Immunol. 2012 Sep 1;189(5):2468-77. doi: 10.4049/jimmunol.1200524. Epub 2012 Jul 27.

Abstract

The opportunistic fungus Candida albicans is one of the leading causes of infections in immunocompromised patients, and innate immunity provides a principal mechanism for protection from the pathogen. In the present work, the role of integrin α(X)β₂ in the pathogenesis of fungal infection was assessed. Both purified α(X)β₂ and α(X)β₂-expressing human epithelial kidney 293 cells recognized and bound to the fungal hyphae of SC5314 strain of C. albicans but not to the yeast form or to hyphae of a strain deficient in the fungal mannoprotein, Pra1. The binding of the integrin to the fungus was inhibited by β-glucans but not by mannans, implicating a lectin-like activity in recognition but distinct in specificity from that of α(M)β₂. Mice deficient in α(X)β₂ were more prone to systemic infection with the LD₅₀ fungal inoculum decreasing 3-fold in α(X)β₂-deficient mice compared with wild-type mice. After challenging i.v. with 1.5 × 10⁴ cell/g, 60% of control C57BL/6 mice died within 14 d compared with 100% mortality of α(X)β₂-deficient mice within 9 d. Organs taken from α(X)β₂-deficient mice 16 h postinfection revealed a 10-fold increase in fungal invasion into the brain and a 2-fold increase into the liver. These data indicate that α(X)β₂ is important for protection against systemic C. albicans infections and macrophage subsets in the liver, Kupffer cells, and in the brain, microglial cells use α(X)β₂ to control fungal invasion.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Candida albicans / pathogenicity*
  • Candidiasis / immunology*
  • Candidiasis / microbiology
  • Candidiasis / prevention & control*
  • Cell Adhesion / immunology
  • Cell Line
  • Cell Movement / immunology
  • Cytophagocytosis / immunology
  • HEK293 Cells
  • Humans
  • Integrin alphaXbeta2 / genetics
  • Integrin alphaXbeta2 / metabolism*
  • Integrin alphaXbeta2 / physiology
  • Leukocytes / immunology
  • Leukocytes / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Receptors, Immunologic / metabolism*
  • Receptors, Immunologic / physiology

Substances

  • Integrin alphaXbeta2
  • Receptors, Immunologic