Cultivated anti-Aspergillus T(H)1 cells

Adoptive transfer of Aspergillus-specific T cells as a novel anti-fungal therapy for hematopoietic stem cell transplant recipients: Progress and challenges

Although newer antifungal drugs have substantially altered the natural history of invasive aspergillosis, the disease still accounts for significant morbidity and mortality in hematopoietic stem cell transplant recipients. Both the evidence supporting a protective role of T cells against this fungal pathogen and the documented efficacy of adoptive transfer of antigen-specific T cells for prophylaxis and treatment of viral infections post-transplant have stimulated much interest towards development of Aspergillus-specific T cells (Asp-STs) for adoptive immunotherapy in the allogeneic transplant setting. In contrast to the remarkable progress with virus-specific T cells, clinical development of fungus-specific T cells is still in its infancy. Several groups have characterized Asp-STs in healthy individuals and patients with malignant hematological diseases, while others sought to develop GMP-compliant methods of expanding or bioengineering Asp-STs ex vivo as immunotherapy. This review highlights the recent advances in this field, and discusses critical issues involved in development and protocol design of Asp-ST immunotherapy.

Protein targets for broad-spectrum mycosis vaccines: quantitative proteomic analysis of Aspergillus and Coccidioides and comparisons with other fungal pathogens

Aspergillus species are responsible for most cases of fatal mold infections in immunocompromised patients, particularly in those receiving hematopoietic stem cell transplants. Experimental vaccines in mouse models have demonstrated a promising avenue of approach for the prevention of aspergillosis, as well as infections caused by other fungal pathogens, such as Coccidioides, the etiological agent of valley fever (coccidioidomycosis). Here, we investigated the hyphal proteomes of Aspergillus fumigatus and Coccidioides posadasii via quantitative MS(E) mass spectrometry with the objective of developing a vaccine that cross-protects against these and other species of fungi. Several homologous proteins with highly conserved sequences were identified and quantified in A. fumigatus and C. posadasii. Many abundant proteins from the cell wall of A. fumigatus present themselves as possible cross-protective vaccine candidates, due to the high degree of sequence homology to other medically relevant fungal proteins and low homologies to human or murine proteins.

[Spanish Paediatric Infectious Diseases Society consensus document on the treatment of fungal infections based on the immune response]

Despite the emergence of new diagnostic and therapeutic methods, invasive fungal infections are still a major cause of morbidity and mortality in immunocompromised and critical patients. Therefore, adjuvant treatments to the standard antifungal therapy are being investigated, with immunity-based therapy being one of the most important. Both immunomodulatory (dendritic and T cells transfusions, colony stimulating factors, interferón-gamma, interleukin 12, fungal vaccines, transfer factors and certain drugs such as chloroquine) and immunotherapeutic modalities (granulocyte transfusions, monoclonal antibodies and intravenous immunoglobulin) have been described. This document aims to summarise currently available data on immunity-based therapy of fungal infections and to provide basic knowledge on the immune response to fungal infections. This helps to understand how, in selected cases, immunity-based therapy may improve the response to standard antifungal treatment. The potential indications of immunity-based therapy in the paediatric patient are reviewed, although there is still a lack of scientific evidence for its use in children.

Healthy human T-Cell Responses to Aspergillus fumigatus antigens

Background

Aspergillus fumigatus is associated with both invasive and allergic pulmonary diseases, in different hosts. The organism is inhaled as a spore, which, if not cleared from the airway, germinates into hyphal morphotypes that are responsible for tissue invasion and resultant inflammation. Hyphae secrete multiple products that function as antigens, evoking both a protective (T_H1–T_H17) and destructive allergic (T_H2) immunity. How Aspergillus allergens (Asp f proteins) participate in the development of allergic sensitization is unknown.

Methodology/Principal Findings

To determine whether Asp f proteins are strictly associated with T_H2 responses, or represent soluble hyphal products recognized by healthy hosts, human T cell responses to crude and recombinant products were characterized by ELISPOT. While responses (number of spots producing IFN-γ, IL-4 or IL-17) to crude hyphal antigen preparations were weak, responses to recombinant Asp f proteins were higher. Recombinant allergens stimulated cells to produce IFN-γ more so than IL-4 or IL-17. Volunteers exhibited a diverse CD4+ and CD8+ T cell antigen recognition profile, with prominent CD4 T_H1-responses to Asp f3 (a putative peroxismal membrane protein), Asp f9/16 (cell wall glucanase), Asp f11 (cyclophilin type peptidyl-prolyl isomerase) and Asp f22 (enolase). Strong IFN-γ responses were reproduced in most subjects tested over 6 month intervals.

Conclusions

Products secreted after conidial germination into hyphae are differentially recognized by protective T cells in healthy, non-atopic individuals. Defining the specificity of the human T cell repertoire, and identifying factors that govern early responses may allow for development of novel diagnostics and therapeutics for both invasive and allergic Aspergillus diseases.