Immunological Analysis of Brain Cancer

Division Of Basic Sciences - Nci

Investigators

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Abstract

Aim 1: The lipid profiling of human glioblastoma (high-grade glioma) cell lines, human low-grade glioma cell lines, and normal human astrocytes was conducted. We found that glioblastoma had a significantly different profile from low-grade glioma and normal astrocytes. Some lipids greatly enriched in glioblastoma were able to stimulate human NKT cells in vitro, indicating that the glioblastoma lipids can be recognized by human NKT cells. Aim 2: We designed and synthesized multiple analogs of sulfatide, a self-glycolipid abundant in the brain, based on the structure of 7DW8-5, a previously reported human NKT cell agonistic lipid antigen. We examined the binding of sulfatide analog loaded CD1d-tetramers to TCRs of iNKT cells using flow cytometry. The results showed that the staining properties of sulfatide-loaded CD1d-tetramers differ depending on the acyl chain structure of the sulfatide analog. Aim 3: The existence and functions of MAIT cells in glioblastoma are less understood than NKT cells. Using a publicly available glioblastoma transcriptomic data set from The Cancer Genome Atlas (TCGA), we found that 8.3% out of 164 patients had MAIT cells in their tumors. The gene signature of MAIT negatively correlated with the disease outcome. MAIT-positive patients had significantly upregulated MR1. Similar to the MAIT cell gene signature, the MR1 expression level, which was higher in MAIT-positive patients, had a significant negative correlation with patient survival. MAIT-positive patients had significantly upregulated genes contained in the Negative Regulation of Immune Response. Multiple neutrophil migration/activation pathways were significantly upregulated in MAIT-positive patients by the Gene Set Enrichment Analysis using a Gene Ontogeny Biological Pathway. Neutrophil degranulation-related genes and myeloid-derived suppressor cells (MDSCs) signature genes were also significantly upregulated in MAIT-positive patients, suggesting that MAIT-positive patients have activated tumor-associated neutrophils (TANs) and MDSCs. Multiple TAN/MDSC-associated immunoregulatory genes were upregulated in MAIT-positive patients, suggesting a MAIT/MR1-TAN/MDSC immunoregulatory pathway. The activity of the pathway was suggested in four additional cancer types. MAIT infiltration into glioblastoma tissues was confirmed by single-cell RNA sequencing data from a different cohort of patients. These data indicate that MAIT cells contribute to myeloid cell-mediated immune suppression in GBM. Aim 4. We are developing viral vector-based vaccines based on ChAdOx-1 and MVA vectors and testing their efficacy against mouse syngeneic glioblastoma in vivo. Using a glioblastoma cell line expressing a model tumor antigen, we found a therapeutic effect of the vaccine against subcutaneously inoculated tumors and a prophylactic effect against orthotopic intracranial tumors. We also discovered endogenous neoantigens and tumor-associated antigens (TAAs) using a newly created mouse tumor antigen discovery pipeline, METRO. The immunogenicity of the antigens was confirmed. Currently, viral vectors expressing the antigens are in production.