Aspergillus fumigatus suppresses the human cellular immune response via gliotoxin-mediated apoptosis of monocytes.
Aspergillus fumigatus (AF) is a ubiquitous mold and is the most common cause of invasive aspergillosis, an important source of morbidity and mortality in immunocompromised hosts. Using cytokine flow cytometry, we assessed the magnitude of functional CD4+ and CD8+ T-cell responses following stimulation with Aspergillus antigens. Relative to those seen with cytomegalovirus (CMV) or superantigen stimulation, responses to Aspergillus antigens were near background levels. Subsequently, we confirmed that gliotoxin, the most abundant mycotoxin produced by AF, was able to suppress functional T-cell responses following CMV or staphylococcal enterotoxin B (SEB) stimulation. Additional studies demonstrated that crude AF filtrates and purified gliotoxin inhibited antigen-presenting cell function and induced the preferential death of monocytes, leading to a marked decrease in the monocyte-lymphocyte ratio. Analysis of caspase-3 activation confirmed that gliotoxin preferentially induced apoptosis of monocytes; similar effects were observed in CD83+ monocyte-derived dendritic cells. Importantly, the physiologic effects of gliotoxin in vitro were observed below concentrations recently observed in the serum of patients with invasive aspergillosis. These studies suggest that the production of gliotoxin by AF may constitute an important immunoevasive mechanism that is mediated by direct effects on antigen-presenting cells and both direct and indirect effects on T cells.
Stanzani
Marta
M
Transplant Immunology Section, Department of Blood and Marrow Transplantation, MD Anderson Cancer Center, SCRB 3.3019, Unit 900, 7455 Fannin St, Houston, TX 77030, USA.
Orciuolo
Enrico
E
Lewis
Russell
R
Kontoyiannis
Dimitrios P
DP
Martins
Sergio L R
SL
St John
Lisa S
LS
Komanduri
Krishna V
KV
D015703:Antigens, CD / Q000276:immunology; D000946:Antigens, Fungal / Q000276:immunology*; D017209:Apoptosis / Q000276:immunology*; D001228:Aspergillosis / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D001232:Aspergillus fumigatus / Q000737:chemistry / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology; D053148:Caspase 3; D020169:Caspases / Q000276:immunology; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology / Q000473:pathology; D004306:Dose-Response Relationship, Immunologic; D004768:Enterotoxins / Q000276:immunology; D005912:Gliotoxin / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007136:Immunoglobulins / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D008562:Membrane Glycoproteins / Q000276:immunology; D009000:Monocytes / Q000276:immunology* / Q000473:pathology; D000097802:CD83 Antigen
D015703:Antigens, CD; D000946:Antigens, Fungal; D053148:Caspase 3; D020169:Caspases; D004768:Enterotoxins; D005912:Gliotoxin; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D000097802:CD83 Antigen; C031818:enterotoxin B, staphylococcal; C505407:CASP3 protein, human