ABSTRACT
Candida glabrata is an important pathogen causing invasive infection associated with a high mortality rate. One mechanism that causes the failure of Candida eradication is an increase in regulatory T cells (Treg), which play a major role in immune suppression and promoting Candida pathogenicity. To date, how C. glabrata induces a Treg response remains unclear. Dendritic cells (DCs) recognition of fungi provides the fundamental signal determining the fate of the T-cell response. This study investigated the interplay between C. glabrata and DCs and its effect on Treg induction. We found that C. glabrata ß-glucan was a major component that interacted with DCs and consequently mediated the Treg response. Blocking the binding of C. glabrata ß-glucan to dectin-1 and complement receptor 3 (CR3) showed that CR3 activation in DCs was crucial for the induction of Treg. Furthermore, a ligand-receptor binding assay showed the preferential binding of C. glabrata ß-glucan to CR3. Our data suggest that C. glabrata ß-glucan potentially mediates the Treg response, probably through CR3-dependent activation in DCs. This study contributes new insights into immune modulation by C. glabrata that may lead to a better design of novel immunotherapeutic strategies for invasive C. glabrata infection.
Subject(s)
Candida glabrata , Dendritic Cells , Macrophage-1 Antigen , T-Lymphocytes, Regulatory , beta-Glucans , Candida glabrata/metabolism , Candida glabrata/pathogenicity , Dendritic Cells/immunology , Dendritic Cells/metabolism , Dendritic Cells/drug effects , T-Lymphocytes, Regulatory/immunology , T-Lymphocytes, Regulatory/metabolism , beta-Glucans/metabolism , beta-Glucans/pharmacology , Animals , Macrophage-1 Antigen/metabolism , Mice , Lectins, C-Type/metabolism , Candidiasis/immunology , Candidiasis/microbiology , Candidiasis/metabolism , Mice, Inbred C57BLABSTRACT
Host-Candida interaction has been broadly studied during Candida albicans infection, with a progressive shift in focus toward non-albicans Candida species. C. krusei is an emerging multidrug resistant pathogen causing rising morbidity and mortality worldwide. Therefore, understanding the interplay between the host immune system and C. krusei is critically important. Candia cell wall ß-glucans play significant roles in the induction of host protective immune responses. However, it remains unclear how C. krusei ß-glucan impacts dendritic cell (DC) responses. In this study, we investigated DC maturation and function in response to ß-glucans isolated from the cell walls of C. albicans, C. tropicalis, and C. krusei. These three distinct Candida ß-glucans had differential effects on expression of the DC marker, CD11c, and on DC maturation. Furthermore, bone-marrow derived DCs (BMDCs) showed enhanced cytokine responses characterized by substantial interleukin (IL)-10 production following C. krusei ß-glucan stimulation. BMDCs stimulated with C. krusei ß-glucan augmented IL-10 production by T cells in tandem with increased IL-10 production by BMDCs. Inhibition of dectin-1 ligation demonstrated that the interactions between dectin-1 on DCs and cell wall ß-glucans varied depending on the Candida species. The effects of C. krusei ß-glucan were partially dependent on dectin-1, and this dependence, in part, led to distinct DC responses. Our study provides new insights into immune regulation by C. krusei cell wall components. These data may be of use in the development of new clinical approaches for treatment of patients with C. krusei infection.
