Characterization and partial purification of Candida albicans Secretory IL-12 Inhibitory Factor.
BACKGROUND
We have previously shown that supernatant from Candida albicans (CA) culture contains a Secretory Interleukin (IL)-12 Inhibitory Factor (CA-SIIF), which inhibits IL-12 production by human monocytes. However, the effect of CA-SIIF on secretion of other cytokines by monocytes is unknown, and detailed characterization of this factor has not been performed.


RESULTS
In this study, we demonstrate that the IL-12 inhibitory activity of CA-SIIF was serum-independent, based on the reduction of IL-12 levels in monocytes stimulated under serum-independent conditions. The minimal inhibitory dose of CA-SIIF was found to be 200 mug/ml. Investigation of CA-SIIF's effect on macrophages IL-12 production in vitro and in vivo also showed that CA-SIIF inhibited IL-12 production by murine macrophages both in vitro (from 571 +/- 24 pg/ml to 387 +/- 87 pg/ml; P = 0.05) and in vivo (from 262 +/- 6 pg/ml to 144 +/- 30 pg/ml; P < 0.05). In addition to IL-12, cytokine array analysis revealed that CA-SIIF induced differential production of other cytokines also. In this regard, reduction in levels were observed for IL-8, IL-10, IL-13, monocyte chemoattractant protein (MCP)-1, MCP-2, macrophage inflammatory protein (MIP)-1, RANTES, etc. In contrast, levels of other chemokines e.g. MCP-4, MIF and MIP-3alpha (P < 0.05) were increased. We also found that CA-SIIF suppressed the maturation of human monocytes to dendritic cells (CD1a expression = 13 +/- 3% vs 36 +/- 2% of the control; P < 0.01). Next, to identify the biochemical nature of CA-SIIF, we separated this factor into a Concanavalin A (ConA)-binding glycoprotein fraction (CA-SIIF-GP) and a non-ConA-binding protein fraction (CA-SIIF-NGP) using ConA affinity chromatography. Both fractions were then tested for this inhibitory effect on human monocyte IL-12 production. CA-SIIF-GP produced a higher inhibitory effect on IL-12 production compared to CA-SIIF-NGP and CA-SIIF crude (P < 0.01), proving that CA-SIIF is a glycoprotein in nature.


CONCLUSIONS
CA-SIIF is a glycoprotein which exhibits serum-independent inhibition of IL-12 production from monocytes in vitro and in vivo, and also modulates differentiation of monocytes into dendritic cells. These results suggest important role for CA-SIIF in interactions of C. albicans with the host immune system.
Wang
Mingyue
M
Center for Medical Mycology, Department of Dermatology, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, Ohio, USA. mingyuewang@gmail.com
Mukherjee
Pranab K
PK
Chandra
Jyotsna
J
Lattif
Ali Abdul
AA
McCormick
Thomas S
TS
Ghannoum
Mahmoud A
MA
D000818:Animals; D002176:Candida albicans / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D002846:Chromatography, Affinity; D016895:Culture Media, Serum-Free; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005656:Fungal Proteins / Q000276:immunology* / Q000302:isolation & purification / Q000494:pharmacology; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D018664:Interleukin-12 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000276:immunology*; D011952:Receptors, Concanavalin A / Q000276:immunology; D012441:Saccharomyces cerevisiae / Q000276:immunology
D016895:Culture Media, Serum-Free; D016207:Cytokines; D005656:Fungal Proteins; D006023:Glycoproteins; D011952:Receptors, Concanavalin A; C027774:concanavalin A-binding glycoproteins; D018664:Interleukin-12