Abstract
Endolysosomal processing has a critical influence on immunogenicity as well as immune polarization of protein antigens. In industrialized countries, allergies affect around 25% of the population. For the rational design of protein-based allergy therapeutics for immunotherapy, a good knowledge of T cell-reactive regions on allergens is required. Thus, we sought to analyze endolysosomal degradation patterns of inhalant allergens. Four major allergens from ragweed, birch, as well as house dust mites were produced as recombinant proteins. Endolysosomal proteases were purified by differential centrifugation from dendritic cells, macrophages, and B cells, and combined with allergens for proteolytic processing. Thereafter, endolysosomal proteolysis was monitored by protein gel electrophoresis and mass spectrometry. We found that the overall proteolytic activity of specific endolysosomal fractions differed substantially, whereas the degradation patterns of the four model allergens obtained with the different proteases were extremely similar. Moreover, previously identified T cell epitopes were assigned to endolysosomal peptides and indeed showed a good overlap with known T cell epitopes for all four candidate allergens. Thus, we propose that the degradome assay can be used as a predictor to determine antigenic peptides as potential T cell epitopes, which will help in the rational design of protein-based allergy vaccine candidates.
Highlights
Over a decade ago, Delamarre et al suggested that differential processing of antigens in lysosomal compartments may directly influence the quality of the subsequent immune response [1]
MHCI molecules are found on almost all cell types and present peptides derived from intracellular antigens, whereas MHCII complexes are constitutively expressed only on professional antigen-presenting cells (APCs) and primarily display extracellular antigens [2]
MHCII molecules are assembled with a chaperone protein called the invariant chain (Ii) in the endoplasmic reticulum, which is trimmed and cleaved in the endosome where the residual part of the invariant chain (CLIP) is replaced by antigenic peptides—a process regulated by HLA-DM [2]
Summary
Delamarre et al suggested that differential processing of antigens in lysosomal compartments may directly influence the quality of the subsequent immune response [1]. MHCI molecules are found on almost all cell types and present peptides derived from intracellular antigens, whereas MHCII complexes are constitutively expressed only on professional antigen-presenting cells (APCs) and primarily display extracellular antigens [2]. 20–30% of antigenic peptides eluted from MHCII molecules have an intracellular origin and are transferred to endolysosomal compartments via mechanisms of autophagy [3]. Antigens are proteolytically processed in endolysosomal compartments and thereafter loaded on the MHCII complex and presented to T cells, which eventually initiate T cell activation. This process is fundamental for the development of an adaptive immune response
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
