Change of annexin binding of monocytes as an expression of cellular response to Candida albicans: down-regulation in severe sepsis

Eur J Clin Microbiol Infect Dis. 2016 Nov;35(11):1787-1793. doi: 10.1007/s10096-016-2728-3. Epub 2016 Aug 3.

Abstract

To study the differences of monocyte activation by albicans and non-albicans species of Candida and its change in sepsis, peripheral blood mononuclear cells were isolated from 17 healthy volunteers and 26 patients with severe sepsis/shock, and incubated in the absence/presence of heat-killed (HK) isolates of four different Candida species and purified β-D-glucan from C.albicans. Experiments were repeated in the presence and absence of inhibitors of intracellular activation pathways. Expression of annexin V on cells membranes of monocytes and lymphocytes, cytoplasmic activity of caspase-3, and DNA fragmentation of monocytes were studied. Membrane expression of annexin V on viable monocytes of healthy volunteers decreased significantly after incubation with C.albicans but not with non-albicans species. The decrease was dose-dependent from the Candida inoculum and by the concentration of β-D-glucan. A relationship with inhibition of apoptosis was found as the activity of caspase-3 activity, and the level of DNA fragmentation were also decreased. Incubation in the absence/presence of inhibitors showed that the decrease by annexin V expression resulted by activation of the dectin-1 pathway and Raf-1 by β-D glucan. The decrease of annexin V(+)/PI(-) expression was not shown on monocytes of patients with severe sepsis/shock, where no effect of inhibitors was found. Decrease of annexin V binding on monocytes can be viewed as a selective response to C.albicans partly effected through activation of dectin-1. This response is down-regulated after a septic insult.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Annexins / metabolism*
  • Candida albicans / immunology*
  • Cell Adhesion*
  • Cells, Cultured
  • Down-Regulation
  • Female
  • Humans
  • Male
  • Middle Aged
  • Monocytes / immunology*
  • Monocytes / microbiology*
  • Sepsis / microbiology*
  • Sepsis / pathology*
  • beta-Glucans / metabolism

Substances

  • Annexins
  • beta-Glucans