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Pathogenic fungi regulate immunity by inducing neutrophilic myeloid-derived suppressor cells.

Rieber N, Singh A, Öz H, Carevic M, Bouzani M, Amich J, Ost M, Ye Z, Ballbach M, Schäfer I, Mezger M, Klimosch SN, Weber AN, Handgretinger R, Krappmann S, Liese J, Engeholm M, Schüle R, Salih HR, Marodi L, Speckmann C, Grimbacher B, Ruland J, Brown GD, Beilhack A, Loeffler J, Hartl D - Cell Host Microbe (2015)

Bottom Line: Mechanistically, pathogenic fungi induce neutrophilic MDSCs through the pattern recognition receptor Dectin-1 and its downstream adaptor protein CARD9.Fungal MDSC induction is further dependent on pathways downstream of Dectin-1 signaling, notably reactive oxygen species (ROS) generation as well as caspase-8 activity and interleukin-1 (IL-1) production.These studies define an innate immune mechanism by which pathogenic fungi regulate host defense.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics I, University of Tübingen, 72076 Tübingen, Germany. Electronic address: nikolaus.rieber@med.uni-tuebingen.de.

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Antifungal Functions(A) In vivo.Left panel: survival in the invasive C. albicans infection model after adoptive MDSC transfer. Before adoptive transfer, isolated MDSCs were pretreated with cytochalasin D (CytD, 1 μg/ml, green line) or with recombinant mouse IL-17A protein (5 μg/mouse, red line).Right panel: C. albicans CFUs in kidneys of BALB/c mice 5 days after adoptive transfer of MDSCs. Bars represent means ± SD.(B) In vitro.Left panel: 1 × 106 human MDSCs were co-cultured with 1 × 105 serum opsonized C. albicans (10:1 ratio) for 3 hr at 37°C in RPMI. Serial dilutions were performed of the cell suspension, and 100 μl was plated onto YPD agar plates containing penicillin and streptomycin. Plates were incubated for 24–48 hr at 37°C, and CFU were enumerated.Middle and right panels: phagocytic capacity of human and murine MDSCs. Middle panel; upper (purple) FACS plots, isolated human granulocytic MDSCs (low-density CD66b+CD33+ cells) were co-cultured with or without GFP-labeled C. albicans (CA) spores (MOI = 1) in RPMI medium at 37°C for 90 min. Lower (red) FACS plots, isolated mouse granulocytic CD11b+Ly6G+ MDSCs were co-cultured with or without GFP-labeled C. albicans spores (MOI = 4) in RPMI medium at 37°C for 90 min. Representative dot blots are shown.Right panel: GFP expression/fluorescence of MDSCs was analyzed by FACS and is given in the right panel as percentage of GFP+ MDSCs.
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fig2: Antifungal Functions(A) In vivo.Left panel: survival in the invasive C. albicans infection model after adoptive MDSC transfer. Before adoptive transfer, isolated MDSCs were pretreated with cytochalasin D (CytD, 1 μg/ml, green line) or with recombinant mouse IL-17A protein (5 μg/mouse, red line).Right panel: C. albicans CFUs in kidneys of BALB/c mice 5 days after adoptive transfer of MDSCs. Bars represent means ± SD.(B) In vitro.Left panel: 1 × 106 human MDSCs were co-cultured with 1 × 105 serum opsonized C. albicans (10:1 ratio) for 3 hr at 37°C in RPMI. Serial dilutions were performed of the cell suspension, and 100 μl was plated onto YPD agar plates containing penicillin and streptomycin. Plates were incubated for 24–48 hr at 37°C, and CFU were enumerated.Middle and right panels: phagocytic capacity of human and murine MDSCs. Middle panel; upper (purple) FACS plots, isolated human granulocytic MDSCs (low-density CD66b+CD33+ cells) were co-cultured with or without GFP-labeled C. albicans (CA) spores (MOI = 1) in RPMI medium at 37°C for 90 min. Lower (red) FACS plots, isolated mouse granulocytic CD11b+Ly6G+ MDSCs were co-cultured with or without GFP-labeled C. albicans spores (MOI = 4) in RPMI medium at 37°C for 90 min. Representative dot blots are shown.Right panel: GFP expression/fluorescence of MDSCs was analyzed by FACS and is given in the right panel as percentage of GFP+ MDSCs.

Mentions: We adoptively transferred T cell-suppressive neutrophilic MDSCs and monitored their impact on survival in fungal infection. While a single dose of adoptively transferred MDSCs was protective in systemic C. albicans infection, MDSCs had no impact on A. fumigatus infection (Figure 1E). Septic shock determines mortality in candidiasis (Spellberg et al., 2005), and the interplay of fungal growth and renal immunopathology was shown to correlate with host survival (Lionakis et al., 2011, 2013; Lionakis and Netea, 2013; Spellberg et al., 2003). Adoptively transferred MDSCs dampened renal T and NK cell activation and systemic Th17 and TNF-α cytokine responses (Figures S1F and S1G). Conversely, supplementing IL-17A dampened the MDSC-mediated protective effect (Figure 2A). Besides these immunomodulatory effects, MDSCs might also act directly antifungal, as our in vitro studies showed that they can phagocytose and kill fungi (Figure 2B). However, direct antifungal effects could hardly explain the beneficial effect of MDSCs in candidiasis: (i) adoptively transferred MDSCs had no effect on fungal burden in vivo (Figure 2A), (ii) inhibition of phagocytosis only partially diminished the protection conferred by MDSCs (Figure 2A), and (iii) MDSCs were exclusively protective in immunocompetent mice (C. albicans infection model), with no effect in immunosuppressed (neutropenic) mice (A. fumigatus infection model).


Pathogenic fungi regulate immunity by inducing neutrophilic myeloid-derived suppressor cells.

Rieber N, Singh A, Öz H, Carevic M, Bouzani M, Amich J, Ost M, Ye Z, Ballbach M, Schäfer I, Mezger M, Klimosch SN, Weber AN, Handgretinger R, Krappmann S, Liese J, Engeholm M, Schüle R, Salih HR, Marodi L, Speckmann C, Grimbacher B, Ruland J, Brown GD, Beilhack A, Loeffler J, Hartl D - Cell Host Microbe (2015)

Antifungal Functions(A) In vivo.Left panel: survival in the invasive C. albicans infection model after adoptive MDSC transfer. Before adoptive transfer, isolated MDSCs were pretreated with cytochalasin D (CytD, 1 μg/ml, green line) or with recombinant mouse IL-17A protein (5 μg/mouse, red line).Right panel: C. albicans CFUs in kidneys of BALB/c mice 5 days after adoptive transfer of MDSCs. Bars represent means ± SD.(B) In vitro.Left panel: 1 × 106 human MDSCs were co-cultured with 1 × 105 serum opsonized C. albicans (10:1 ratio) for 3 hr at 37°C in RPMI. Serial dilutions were performed of the cell suspension, and 100 μl was plated onto YPD agar plates containing penicillin and streptomycin. Plates were incubated for 24–48 hr at 37°C, and CFU were enumerated.Middle and right panels: phagocytic capacity of human and murine MDSCs. Middle panel; upper (purple) FACS plots, isolated human granulocytic MDSCs (low-density CD66b+CD33+ cells) were co-cultured with or without GFP-labeled C. albicans (CA) spores (MOI = 1) in RPMI medium at 37°C for 90 min. Lower (red) FACS plots, isolated mouse granulocytic CD11b+Ly6G+ MDSCs were co-cultured with or without GFP-labeled C. albicans spores (MOI = 4) in RPMI medium at 37°C for 90 min. Representative dot blots are shown.Right panel: GFP expression/fluorescence of MDSCs was analyzed by FACS and is given in the right panel as percentage of GFP+ MDSCs.
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fig2: Antifungal Functions(A) In vivo.Left panel: survival in the invasive C. albicans infection model after adoptive MDSC transfer. Before adoptive transfer, isolated MDSCs were pretreated with cytochalasin D (CytD, 1 μg/ml, green line) or with recombinant mouse IL-17A protein (5 μg/mouse, red line).Right panel: C. albicans CFUs in kidneys of BALB/c mice 5 days after adoptive transfer of MDSCs. Bars represent means ± SD.(B) In vitro.Left panel: 1 × 106 human MDSCs were co-cultured with 1 × 105 serum opsonized C. albicans (10:1 ratio) for 3 hr at 37°C in RPMI. Serial dilutions were performed of the cell suspension, and 100 μl was plated onto YPD agar plates containing penicillin and streptomycin. Plates were incubated for 24–48 hr at 37°C, and CFU were enumerated.Middle and right panels: phagocytic capacity of human and murine MDSCs. Middle panel; upper (purple) FACS plots, isolated human granulocytic MDSCs (low-density CD66b+CD33+ cells) were co-cultured with or without GFP-labeled C. albicans (CA) spores (MOI = 1) in RPMI medium at 37°C for 90 min. Lower (red) FACS plots, isolated mouse granulocytic CD11b+Ly6G+ MDSCs were co-cultured with or without GFP-labeled C. albicans spores (MOI = 4) in RPMI medium at 37°C for 90 min. Representative dot blots are shown.Right panel: GFP expression/fluorescence of MDSCs was analyzed by FACS and is given in the right panel as percentage of GFP+ MDSCs.
Mentions: We adoptively transferred T cell-suppressive neutrophilic MDSCs and monitored their impact on survival in fungal infection. While a single dose of adoptively transferred MDSCs was protective in systemic C. albicans infection, MDSCs had no impact on A. fumigatus infection (Figure 1E). Septic shock determines mortality in candidiasis (Spellberg et al., 2005), and the interplay of fungal growth and renal immunopathology was shown to correlate with host survival (Lionakis et al., 2011, 2013; Lionakis and Netea, 2013; Spellberg et al., 2003). Adoptively transferred MDSCs dampened renal T and NK cell activation and systemic Th17 and TNF-α cytokine responses (Figures S1F and S1G). Conversely, supplementing IL-17A dampened the MDSC-mediated protective effect (Figure 2A). Besides these immunomodulatory effects, MDSCs might also act directly antifungal, as our in vitro studies showed that they can phagocytose and kill fungi (Figure 2B). However, direct antifungal effects could hardly explain the beneficial effect of MDSCs in candidiasis: (i) adoptively transferred MDSCs had no effect on fungal burden in vivo (Figure 2A), (ii) inhibition of phagocytosis only partially diminished the protection conferred by MDSCs (Figure 2A), and (iii) MDSCs were exclusively protective in immunocompetent mice (C. albicans infection model), with no effect in immunosuppressed (neutropenic) mice (A. fumigatus infection model).

Bottom Line: Mechanistically, pathogenic fungi induce neutrophilic MDSCs through the pattern recognition receptor Dectin-1 and its downstream adaptor protein CARD9.Fungal MDSC induction is further dependent on pathways downstream of Dectin-1 signaling, notably reactive oxygen species (ROS) generation as well as caspase-8 activity and interleukin-1 (IL-1) production.These studies define an innate immune mechanism by which pathogenic fungi regulate host defense.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics I, University of Tübingen, 72076 Tübingen, Germany. Electronic address: nikolaus.rieber@med.uni-tuebingen.de.

Show MeSH
Related in: MedlinePlus