CcpA- and Shm2-Pulsed Myeloid Dendritic Cells Induce T-Cell Activation and Enhance the Neutrophilic Oxidative Burst Response to Aspergillus fumigatus.

Lukas Page,Jasmin Lother,Juergen Loeffler,Maximilian Bauser,Vera Voltersen,Axel A Brakhage,Max Topp,Janka Teutschbein,Lea Strobel,Olaf Kniemeyer,Julia Wallstabe,Sebastian Wurster,Hermann Einsele,Peter Hortschansky,Charles Oliver Morton

doi:10.3389/fimmu.2021.659752

Abstract

Aspergillus fumigatus causes life-threatening opportunistic infections in immunocompromised patients. As therapeutic outcomes of invasive aspergillosis (IA) are often unsatisfactory, the development of targeted immunotherapy remains an important goal. Linking the innate and adaptive immune system, dendritic cells are pivotal in anti-Aspergillus defense and have generated interest as a potential immunotherapeutic approach in IA. While monocyte-derived dendritic cells (moDCs) require ex vivo differentiation, antigen-pulsed primary myeloid dendritic cells (mDCs) may present a more immediate platform for immunotherapy. To that end, we compared the response patterns and cellular interactions of human primary mDCs and moDCs pulsed with an A. fumigatus lysate and two A. fumigatus proteins (CcpA and Shm2) in a serum-free, GMP-compliant medium. CcpA and Shm2 triggered significant upregulation of maturation markers in mDCs and, to a lesser extent, moDCs. Furthermore, both A. fumigatus proteins elicited the release of an array of key pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, IL-8, and CCL3 from both DC populations. Compared to moDCs, CcpA- and Shm2-pulsed mDCs exhibited greater expression of MHC class II antigens and stimulated stronger proliferation and IFN-γ secretion from autologous CD4+ and CD8+ T-cells. Moreover, supernatants of CcpA- and Shm2-pulsed mDCs significantly enhanced the oxidative burst in allogeneic neutrophils co-cultured with A. fumigatus germ tubes. Taken together, our in vitro data suggest that ex vivo CcpA- and Shm2-pulsed primary mDCs have the potential to be developed into an immunotherapeutic approach to tackle IA.

Highlights

Aspergillus fumigatus remains the most common mold pathogen causing life-threatening infections in immunocompromised patients such as hematopoietic stem cell transplant (HSCT) recipients
After 18 h of stimulation, limited induction of CD40, CD80 and CD86 was found in monocyte-derived dendritic cells (moDCs) stimulated with the proteinaceous antigens, whereas stimulation with the lysate did not alter surface expression of the maturation markers and co-stimulatory molecules that were tested (Figure 1A)
For Shm2, we evaluated the temporal kinetics of maturation marker expression by comparing myeloid dendritic cells (mDCs) exposed to 1 and 5 μg/mL Shm2 for 6 versus 18 hours

Summary

Introduction

Aspergillus fumigatus remains the most common mold pathogen causing life-threatening infections in immunocompromised patients such as hematopoietic stem cell transplant (HSCT) recipients. To meet the need for more specific therapeutic options, a spectrum of immunotherapeutic approaches have been developed to enhance host defence and support fungal clearance [1]. Dendritic cells (DCs) are an important cornerstone in the host response to A. fumigatus and have been proposed as a potential immunotherapeutic tool in IA. Phagocytic immature DCs patrol their environment and recognize pathogenic antigens via pattern recognition receptors (PRRs). Activated DCs present processed antigens to CD4+ and CD8+ T-cells and orchestrate the response of other innate and adaptive immune cell subsets through cytokine release and co-stimulatory surface receptors [2]. DCs pulsed with live A. fumigatus or transfected with fungal RNA accelerated functional recovery of antifungal TH1 immunity in a murine HSCT model and had significantly greater therapeutic efficacy against murine IA compared to adoptive T-helper cell transfer [4]

Methods

Results

Conclusion