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Impaired T cell responsiveness to interleukin-6 in hematological patients with invasive aspergillosis.

Camargo JF, Bhimji A, Kumar D, Kaul R, Pavan R, Schuh A, Seftel M, Lipton JH, Gupta V, Humar A, Husain S - PLoS ONE (2015)

Bottom Line: While IFN-γ/STAT1 signaling was similar between groups, naïve T cells from patients with IA, but not those with mucormycosis, exhibited reduced responsiveness to IL-6 as measured by STAT3 phosphorylation.Furthermore, IL-6 increased Aspergillus-induced IL-17 production in culture supernatants from healthy and hematological controls but not in patients with IA.Altogether, these observations suggest an important role for dectin-1 and the IL-6/STAT3 pathway in protective immunity against Aspergillus.

View Article: PubMed Central - PubMed

Affiliation: Transplant Infectious Diseases, Multi-Organ Transplant Program, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Medicine, University Health Network, Toronto, Ontario, Canada.

ABSTRACT
Invasive mold infections (IMI) are among the most devastating complications following chemotherapy and hematopoietic stem cell transplantation (HSCT), with high mortality rates. Yet, the molecular basis for human susceptibility to invasive aspergillosis (IA) and mucormycosis remain poorly understood. Herein, we aimed to characterize the immune profile of individuals with hematological malignancies (n = 18) who developed IMI during the course of chemotherapy or HSCT, and compared it to that of hematological patients who had no evidence of invasive fungal infection (n = 16). First, we measured the expression of the pattern recognition receptors pentraxin 3, dectin-1, and Toll-like receptors (TLR) 2 and 4 in peripheral blood of chemotherapy and HSCT recipients with IMI. Compared to hematological controls, individuals with IA and mucormycosis had defective expression of dectin-1; in addition, patients with mucormycosis had decreased TLR2 and increased TLR4 expression. Since fungal recognition via dectin-1 favors T helper 17 responses and the latter are highly dependent on activation of the signal transducer and activator of transcription (STAT) 3, we next used phospho-flow cytometry to measure the phosphorylation of the transcription factors STAT1 and STAT3 in response to interferon-gamma (IFN-γ) and interleukin (IL)-6, respectively. While IFN-γ/STAT1 signaling was similar between groups, naïve T cells from patients with IA, but not those with mucormycosis, exhibited reduced responsiveness to IL-6 as measured by STAT3 phosphorylation. Furthermore, IL-6 increased Aspergillus-induced IL-17 production in culture supernatants from healthy and hematological controls but not in patients with IA. Altogether, these observations suggest an important role for dectin-1 and the IL-6/STAT3 pathway in protective immunity against Aspergillus.

No MeSH data available.


Related in: MedlinePlus

Pattern recognition receptors in hematological patients with IMI.(a) Serum levels of PTX3 (ng/mL) measured by immunoassay in healthy controls (blue circles; n = 6), hematological patients with IA (red squares; n = 12) or mucormycosis (black inverted triangles; n = 4) and non-IFI hematological controls (green triangles; n = 16) are shown. *p<0.05, **p<0.01, and ***p<0.005 using the unpaired two-tailed Student’s t-test. (b-d) Surface expression of dectin-1 (b), TLR2 (c) and TLR4 (d) on monocytes was measured by flow cytometry. Gating on CD45highCD14+ cells was performed in order to avoid interference of the analysis by potential blasts in leukemic patients with residual disease. Dot plots represent the percentage of monocytes (CD45highCD14+ cells) expressing dectin-1, TLR2 or TLR4 in peripheral blood samples from healthy controls (blue circles; n = 7), hematological patients with IA (red squares; n = 12) or mucormycosis (black triangles; n = 4) and non-IFI hematological controls (green triangles; n = 13). *p<0.05, **p<0.01 using the unpaired two-tailed Student’s t-test. All data are shown as mean ± s.e.m.
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pone.0123171.g001: Pattern recognition receptors in hematological patients with IMI.(a) Serum levels of PTX3 (ng/mL) measured by immunoassay in healthy controls (blue circles; n = 6), hematological patients with IA (red squares; n = 12) or mucormycosis (black inverted triangles; n = 4) and non-IFI hematological controls (green triangles; n = 16) are shown. *p<0.05, **p<0.01, and ***p<0.005 using the unpaired two-tailed Student’s t-test. (b-d) Surface expression of dectin-1 (b), TLR2 (c) and TLR4 (d) on monocytes was measured by flow cytometry. Gating on CD45highCD14+ cells was performed in order to avoid interference of the analysis by potential blasts in leukemic patients with residual disease. Dot plots represent the percentage of monocytes (CD45highCD14+ cells) expressing dectin-1, TLR2 or TLR4 in peripheral blood samples from healthy controls (blue circles; n = 7), hematological patients with IA (red squares; n = 12) or mucormycosis (black triangles; n = 4) and non-IFI hematological controls (green triangles; n = 13). *p<0.05, **p<0.01 using the unpaired two-tailed Student’s t-test. All data are shown as mean ± s.e.m.

Mentions: The first cellular line of defense against filamentous fungi consists of epithelial cells and phagocytes, particularly pulmonary alveolar macrophages [5,8]. Detection of fungal antigens such as beta-glucans, galactomannan and zymosan by epithelial and phagocytic cells occurs via pattern recognition receptors (PRRs), which recognize highly conserved structures expressed on the cell wall of invading fungi. Pentraxin 3 (PTX3) is a soluble PRR that is rapidly released by neutrophils and other cell types in response to inflammatory signals [9]. PTX3 has potent anti-Aspergillus activity [9] but its role in response to other filamentous fungi is unknown. Genetic deficiency of PTX3 is associated with increased risk of IA in HSCT recipients [10]. Circulating levels of PTX3 are elevated in hematological patients with IMI and normalize with successful antifungal therapy [11]. In our cohort, PTX3 levels were significantly higher in patients with IMI when compared to healthy controls (1.67 ± 0.72 vs. 0.61 ± 0.32, ng/mL, respectively; p = 0.0001) but they were similar between patients with IMI and non-IFI hematological controls (S1A Fig). Compared to healthy volunteers, serum PTX3 levels were significantly elevated in patients with IA (0.61 ± 0.32 vs. 1.57 ± 0.69, ng/mL, respectively; p = 0.0009) (Fig 1A). However, PTX3 levels did not discriminate between cases of IA and patients with mucormycosis (1.57 ± 0.69 vs. 1.97 ± 0.84, ng/mL, respectively; p = 0.43) or hematological controls (1.57 ± 0.69 vs. 1.63 ± 0. 7, ng/mL, respectively; p = 0.82). This observation is not surprising as PTX3 is not highly specific for Aspergillus infection [8].


Impaired T cell responsiveness to interleukin-6 in hematological patients with invasive aspergillosis.

Camargo JF, Bhimji A, Kumar D, Kaul R, Pavan R, Schuh A, Seftel M, Lipton JH, Gupta V, Humar A, Husain S - PLoS ONE (2015)

Pattern recognition receptors in hematological patients with IMI.(a) Serum levels of PTX3 (ng/mL) measured by immunoassay in healthy controls (blue circles; n = 6), hematological patients with IA (red squares; n = 12) or mucormycosis (black inverted triangles; n = 4) and non-IFI hematological controls (green triangles; n = 16) are shown. *p<0.05, **p<0.01, and ***p<0.005 using the unpaired two-tailed Student’s t-test. (b-d) Surface expression of dectin-1 (b), TLR2 (c) and TLR4 (d) on monocytes was measured by flow cytometry. Gating on CD45highCD14+ cells was performed in order to avoid interference of the analysis by potential blasts in leukemic patients with residual disease. Dot plots represent the percentage of monocytes (CD45highCD14+ cells) expressing dectin-1, TLR2 or TLR4 in peripheral blood samples from healthy controls (blue circles; n = 7), hematological patients with IA (red squares; n = 12) or mucormycosis (black triangles; n = 4) and non-IFI hematological controls (green triangles; n = 13). *p<0.05, **p<0.01 using the unpaired two-tailed Student’s t-test. All data are shown as mean ± s.e.m.
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pone.0123171.g001: Pattern recognition receptors in hematological patients with IMI.(a) Serum levels of PTX3 (ng/mL) measured by immunoassay in healthy controls (blue circles; n = 6), hematological patients with IA (red squares; n = 12) or mucormycosis (black inverted triangles; n = 4) and non-IFI hematological controls (green triangles; n = 16) are shown. *p<0.05, **p<0.01, and ***p<0.005 using the unpaired two-tailed Student’s t-test. (b-d) Surface expression of dectin-1 (b), TLR2 (c) and TLR4 (d) on monocytes was measured by flow cytometry. Gating on CD45highCD14+ cells was performed in order to avoid interference of the analysis by potential blasts in leukemic patients with residual disease. Dot plots represent the percentage of monocytes (CD45highCD14+ cells) expressing dectin-1, TLR2 or TLR4 in peripheral blood samples from healthy controls (blue circles; n = 7), hematological patients with IA (red squares; n = 12) or mucormycosis (black triangles; n = 4) and non-IFI hematological controls (green triangles; n = 13). *p<0.05, **p<0.01 using the unpaired two-tailed Student’s t-test. All data are shown as mean ± s.e.m.
Mentions: The first cellular line of defense against filamentous fungi consists of epithelial cells and phagocytes, particularly pulmonary alveolar macrophages [5,8]. Detection of fungal antigens such as beta-glucans, galactomannan and zymosan by epithelial and phagocytic cells occurs via pattern recognition receptors (PRRs), which recognize highly conserved structures expressed on the cell wall of invading fungi. Pentraxin 3 (PTX3) is a soluble PRR that is rapidly released by neutrophils and other cell types in response to inflammatory signals [9]. PTX3 has potent anti-Aspergillus activity [9] but its role in response to other filamentous fungi is unknown. Genetic deficiency of PTX3 is associated with increased risk of IA in HSCT recipients [10]. Circulating levels of PTX3 are elevated in hematological patients with IMI and normalize with successful antifungal therapy [11]. In our cohort, PTX3 levels were significantly higher in patients with IMI when compared to healthy controls (1.67 ± 0.72 vs. 0.61 ± 0.32, ng/mL, respectively; p = 0.0001) but they were similar between patients with IMI and non-IFI hematological controls (S1A Fig). Compared to healthy volunteers, serum PTX3 levels were significantly elevated in patients with IA (0.61 ± 0.32 vs. 1.57 ± 0.69, ng/mL, respectively; p = 0.0009) (Fig 1A). However, PTX3 levels did not discriminate between cases of IA and patients with mucormycosis (1.57 ± 0.69 vs. 1.97 ± 0.84, ng/mL, respectively; p = 0.43) or hematological controls (1.57 ± 0.69 vs. 1.63 ± 0. 7, ng/mL, respectively; p = 0.82). This observation is not surprising as PTX3 is not highly specific for Aspergillus infection [8].

Bottom Line: While IFN-γ/STAT1 signaling was similar between groups, naïve T cells from patients with IA, but not those with mucormycosis, exhibited reduced responsiveness to IL-6 as measured by STAT3 phosphorylation.Furthermore, IL-6 increased Aspergillus-induced IL-17 production in culture supernatants from healthy and hematological controls but not in patients with IA.Altogether, these observations suggest an important role for dectin-1 and the IL-6/STAT3 pathway in protective immunity against Aspergillus.

View Article: PubMed Central - PubMed

Affiliation: Transplant Infectious Diseases, Multi-Organ Transplant Program, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Medicine, University Health Network, Toronto, Ontario, Canada.

ABSTRACT
Invasive mold infections (IMI) are among the most devastating complications following chemotherapy and hematopoietic stem cell transplantation (HSCT), with high mortality rates. Yet, the molecular basis for human susceptibility to invasive aspergillosis (IA) and mucormycosis remain poorly understood. Herein, we aimed to characterize the immune profile of individuals with hematological malignancies (n = 18) who developed IMI during the course of chemotherapy or HSCT, and compared it to that of hematological patients who had no evidence of invasive fungal infection (n = 16). First, we measured the expression of the pattern recognition receptors pentraxin 3, dectin-1, and Toll-like receptors (TLR) 2 and 4 in peripheral blood of chemotherapy and HSCT recipients with IMI. Compared to hematological controls, individuals with IA and mucormycosis had defective expression of dectin-1; in addition, patients with mucormycosis had decreased TLR2 and increased TLR4 expression. Since fungal recognition via dectin-1 favors T helper 17 responses and the latter are highly dependent on activation of the signal transducer and activator of transcription (STAT) 3, we next used phospho-flow cytometry to measure the phosphorylation of the transcription factors STAT1 and STAT3 in response to interferon-gamma (IFN-γ) and interleukin (IL)-6, respectively. While IFN-γ/STAT1 signaling was similar between groups, naïve T cells from patients with IA, but not those with mucormycosis, exhibited reduced responsiveness to IL-6 as measured by STAT3 phosphorylation. Furthermore, IL-6 increased Aspergillus-induced IL-17 production in culture supernatants from healthy and hematological controls but not in patients with IA. Altogether, these observations suggest an important role for dectin-1 and the IL-6/STAT3 pathway in protective immunity against Aspergillus.

No MeSH data available.


Related in: MedlinePlus