Project description:To identify potential T-cell targets for Triple-Negative Breast Cancer (TNBC) vaccination, we examined the effect of the pro-inflammatory cytokine interferon-γ (IFNγ) on the transcriptome, proteome and immunopeptidome of the TNBC cell line MDA-MB-231. Using high resolution mass spectrometry, we identified a total of 84,131 peptides from 9,647 source proteins presented by human leukocyte antigen (HLA)-I and HLA-II alleles. Treatment with IFNγ resulted in a remarkable remoulding of the immunopeptidome, with only a 34% overlap between untreated and treated cells across the HLA-I immunopeptidome, and expression of HLA-II only on treated cells. IFNγ increased the overall number, diversity and abundance of the immunopeptidome, as well as the proportion of coverage of source antigens. The suite of peptides displayed under conditions of IFNγ treatment included many known tumour associated antigens, with the HLA-II repertoire sampling 265 breast cancer associated antigens absent from those sampled by HLA-I. Quantitative analysis of the transcriptome (10,248 transcripts) and proteome (6783 proteins) of these cells revealed 229 proteins and transcripts were commonly differentially expressed, most of which involved in downstream targets of IFNγ signalling including components of the antigen processing machinery such as tapasin and HLA. However, these changes in protein expression did not explain the dramatic modulation of the immunopeptidome following IFNγ treatment. These results demonstrate the high degree of plasticity in the immunopeptidome TNBC cells following cytokine stimulation and provide evidence that under pro-inflammatory conditions a greater variety of HLA-I and HLA-II vaccine targets are unveiled to the immune system. This has important implications for the development of personalised cancer vaccination strategies.
Project description:ER aminopeptidase 1 (ERAP1) is an ER-resident aminopeptidase that excises N-terminal residues off peptides that then bind onto Major Histocompatibility Complex I molecules (MHC-I) and indirectly modulates adaptive immune responses. ERAP1 contains an allosteric regulatory site that accommodates the C-terminus of only some peptide substrates, raising questions about its exact influence on antigen presentation and the potential of allosteric inhibition for cancer immunotherapy. We used an inhibitor that targets this regulatory site to study its effect on the immunopeptidome of a human cancer cell line. The immunopeptidomes of allosterically inhibited and ERAP1 knockout cells contain high-affinity peptides with sequence motifs consistent with the cellular HLA class I haplotypes, but were strikingly different in peptide composition. Compared to knockout cells, allosteric inhibition did not affect the length distribution of peptides and skewed the peptide repertoire both in terms of sequence motifs and HLA allele utilization, indicating significant mechanistic differences between the two ways of disrupting ERAP1 function. These findings suggest that the regulatory site of ERAP1 plays distinct roles in antigenic peptide selection, which should be taken into consideration when designing therapeutic interventions targeting the cancer immunopeptidome.
Project description:In malaria, T cells play a dual role by both restricting parasite growth and mediating immunopathology such as the deadly neuroinflammation called cerebral malaria. During experimental cerebral malaria (ECM), IFN produced by CD4 T cells promotes CD8 T cell sequestration in brain capillaries, resulting in endothelial damage, oedema and death. However the antigen-presenting cells controlling the development of CD4 T cell responses, as well as the antigens recognized by these CD4 T cells, are unknown. Here we used mass spectrometry to characterize the MHC II immunopeptidome presented by dendritic cells during blood stage malaria in C57BL/6 mice. We identified 14 MHC II ligands derived from 13 conserved Plasmodium berghei proteins that we validated in vivo. This work profiles the first MHC II immunopeptidome in a mouse model of blood stage malaria.
Project description:This study utilized mass spectrometry-based proteogenomic profiling to identify the HLA-I immunopeptidome enriched from HepG2 cell. HepG2 WES-based and the COSMIC-based mutation database were generated and utilized to identify HepG2-specific mutant immunopeptides