Invasive aspergillosis is a frequent complication in immunocompromised individuals, and it continues to be an important cause of mortality in patients undergoing hematopoietic stem cell transplantation. In addition to antifungal therapy used for mycoses, immune-modulatory molecules such as cytokines and chemokines can modify the host immune response and exhibit a promising form of antimicrobial therapeutics to combat invasive fungal diseases. Cytokine and chemokine profiles may also be applied as biomarkers during fungal infections and clinical research has demonstrated different activation patterns of cytokines in invasive mycoses such as aspergillosis. In this review, we summarize different aspects of cytokines that have been described to date and provide possible future directions in research on invasive pulmonary aspergillosis following hematopoietic stem cell transplantation. These findings suggest that cytokines and chemokines may serve as useful biomarkers to improve diagnosis and monitoring of infection.
Models | Samples | Methods | Major Findings | Interpretation | |||||||||||
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Cytokines | Chemokines | Others | |||||||||||||
In vitro | |||||||||||||||
iDC + A. fumigatus-small germinating conidia (6 h of stimulation) |
Infected iDCs | Dectin-1 Y238X Stop Codon PolymorphismqRT-PCR | + heat-killed A. fumigatus hyphae + live A. fumigatus conidia |
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A. fumigatus germ tubes induced the expression of genes associated with recognition and phagocytosis in iDCs with a time-dependent manner. | ||||||||
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Dectin-1 Y238X resulted in the reduction of pro-inflammatory cytokines due to the Dectin-1 receptor, which is known to play a role in fungal cell wall β-glucan recognition. | [27][40] | iDC + A. fumigatus antigen Aspf1 |
Infected iDCs | qRT-PCR |
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BEAS-2B (Respiratory epithelial cells) | Dectin-1 blockade by siRNA + Stimuli (β-glucan or Aspergillus conidia) |
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Dectin-1 expressed on epithelial cells contributes to the production of cytokines.
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Aspf1, a member of a family of conserved RNases, induces a pro-inflammatory cytokine response. | ||||||||
[ | 28 | ] | [ | 41 | ] | NK cells obtained from PBMCs + A. fumigatus hyphae (6 h of stimulation) |
Infected NK cells | ||||||||
PBMCs from allogeneic HSCT | NOD2 genetic variation - P268S (TT-genotype) + A. fumigatus conidia - complete NOD deficiency + | qRT-PCR | A. fumigatus conidia |
Infected in TT-genotype compared with infected in CC-and CT-genotype
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Aspergillus infected compared with uninfected
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Human NOD2 deficiency reduces Aspergillus |
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NK cells reveal the expression and release of immunomodulatory molecules involved in antifungal immune responses. | |||||
-induced inflammatory cytokines. | [ | 29 | ] | [ | 42] | In vivo | |||||||||
Human PMBCs from solid-organ transplant recipients |
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IL1B rs16944 SNP
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Both IL1B rs16944 and IL1RN rs419598 SNPs effect Aspergillus-induced cytokine release. | [30][43] | Mice CD1 strain infected by intranasal instillation with A. fumigatus conidia (N = 24) | Mouse whole-lung homogenates |
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Macrophages from healthy blood donors | IL10 SNP with GG genotype + A. fumigatus conidia |
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| Immunocompetent mice: Infected vs. Saline controls
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Susceptibility to IA is associated with a high level of TNF-α at the site of infection and the upregulation of a network of TNF-α–related genes. | ||||||||||
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IL-10 overexpression influences IA by suppressing antifungal immunity. | [31][44] | Immunosuppressed mice: Infected vs. Saline controls
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Immunocompetent vs. Immunosuppressed mice
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BALB/c mice with HSCT + Aspergillus (N = 16) |
Dectin-1 knockout mice |
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Dectin-1 modulates immunity and tolerance via IFN-γ / IL-10 production, and both cytokines activate the protection of Th1/Treg antifungal responses. | [28][41] | BALB/c mice infected by intranasal instillation with A. fumigatus proteases, Aspf5 and Aspf13 (N = 20) |
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Nod2-deficient (Nod2-/-) C57BL/6 mice + Aspergillus (lethal dose) (N = 22) | Mouse lung homogenates |
Nod2-/- deficient mice (Splenocytes) |
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| Infected vs. PBS controls
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| A. fumigatus secreted allergen proteases, Aspf5 and Aspf13, are important for induction of Th2 cytokines secretion and increased IgE levels, which are fundamental features of allergic asthma and an indication of disease severity. | ||||||||
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NOD2 augments Aspergillus-induced cytokine responses and results in resistance to Aspergillus infection. | [29][42] | Clinical study | |||||||||||
Clinical study | Adult hematology patients with proven/probable IFD (N = 172) |
Serum | |||||||||||||
Patients who developed IA post HSCT (N = 71) Non-HSCT patients with IA (N = 21) |
Y238X Stop Codon Polymorphism | ELISA |
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In vivo |
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− | Dectin-1 Y238X heterozygosity had a limited influence on susceptibility to IA. | [High IL-2R and CCL2 concentrations as indicators for the risk of developing IFD. | ||||||||
32 | ] | [ | 45 | ] | Adult hematology patients with probable/possible IA (N = 43) |
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Hematological patients undergoing allogeneic HSCT (N = 310) |
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ELISA | NOD2 genetic variation - P268S SNP |
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Genetic deficiency of NOD2
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results in an alteration of cytokine production in response to Aspergillus infection.
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[High serum IL-8 levels were highly specific and highly sensitive for the diagnosis of IA. | ||||||
29 | ] | [ | 42 | ] | Patients diagnosed with IA (N = 48) |
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An allograft with IA (N = 81) or without IA (N = 58) |
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ELISA | CXCL10 genetic variation - C+11101T - C+1642G - A1101G |
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BAL
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Alveolar cytokines might be useful in supporting current diagnostic approaches for IPA biomarkers. IL-8 was the best performing analyte with the most relevant discriminator between cases of IPA and controls. |
Models | Polymorphism | Major Findings | Interpretation | Ref. | |
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Cytokines | Others | ||||
In vitro | |||||
PBMCs | |||||
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Polymorphisms in CXCL10 altered chemokine secretion and increased the risk of IA after alloSCT. | [ | 27 | ] | [ | 40] |