Glioblastoma is the most aggressive brain malignancy, for which immunotherapy has failed to prolong survival. Glioblastoma-associated immune infiltrates are dominated by tumor-associated macrophages and microglia (TAMs), which are key mediators of immune suppression and resistance to immunotherapy. We and others demonstrated aberrant expression of glycans in different cancer types. These tumor-associated glycans trigger inhibitory signaling in TAMs through glycan-binding receptors. We investigated the glioblastoma glycocalyx as a tumor-intrinsic immune suppressor. We detected increased expression of both tumor-associated truncated O-linked glycans and their receptor, macrophage galactose-type lectin (MGL), on CD163+ TAMs in glioblastoma patient-derived tumor tissues. In an immunocompetent orthotopic glioma mouse model overexpressing truncated O-linked glycans (MGL ligands), high-dimensional mass cytometry revealed a wide heterogeneity of infiltrating myeloid cells with increased infiltration of PD-L1+ TAMs as well as distant alterations in the bone marrow (BM). Our results demonstrate that glioblastomas exploit cell surface O-linked glycans for local and distant immune modulation.

Background: Patients affected by different types of autoimmune diseases, including common conditions such as Multiple Sclerosis (MS) and Rheumatoid Arthritis (RA), are often treated with immunosuppressants to suppress disease activity. It is not fully understood how the SARS-CoV-2 specific humoral and cellular immunity induced by infection and/or upon vaccination is affected by immunosuppressants.Methods: The dynamics of cellular immune reactivation upon vaccination of SARS-CoV-2 experienced MS patients treated with the humanized anti-CD20 monoclonal antibody ocrelizumab (OCR) and RA patients treated with methotrexate (MTX) monotherapy were analyzed at great depth via high-dimensional flow cytometry of whole blood samples upon vaccination with the SARS-CoV-2 mRNA-1273 (Moderna) vaccine. Longitudinal B and T cell immune responses were compared to SARS-CoV-2 experienced healthy controls (HC) before and 7-days after the first and second vaccination.Results: OCR-treated MS patients exhibit a preserved recall response of CD8+ T central memory cells following first vaccination compared to healthy controls and a similar CD4+ circulating T follicular helper 1 and T helper 1 dynamics, whereas humoral and B cell responses were strongly impaired resulting in absence of SARS-CoV-2 specific humoral immunity. MTX treatment significantly delayed antibody levels and B reactivation following the first vaccination, including sustained inhibition of overall reactivation marker dynamics of the responding CD4+ and CD8+ T cells.Conclusion: Together, these findings indicate that SARS-CoV-2 experienced MS-OCR patients still benefit from vaccination by inducing a broad CD8+ T cell response which can contribute to milder disease outcome. A delayed dynamics of vaccine-induced immunological recall in RA-MTX patients support repeated vaccine strategies to protect against future variants of concern, especially for these patients.Funding: This research project was supported by ZonMw (The Netherlands Organization for Health Research and Development, #10430072010007), the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement (#792532 and #860003), the European Commission (SUPPORT-E, #101015756) and by PPOC (#20_21 L2506), the NHMRC Leadership Investigator Grant (#1173871).

The chemokine receptor CXCR3 is expressed on immune cells to co-ordinate lymphocyte activation and migration. CXCR3 binds three chemokine ligands, CXCL9, CXCL10 and CXCL11. These ligands display distinct expression patterns and ligand signaling biases; however, how each ligand functions individually and collaboratively is incompletely understood. CXCL9 and CXCL10 are considered pro-inflammatory chemokines during viral infection, while CXCL11 may induce a tolerizing state. The investigation of the individual role of CXCL11 in vivo has been hampered as C57BL/6 mice carry several mutations that result in a null allele. Here, CRISPR/Cas9 was used to correct these mutations on a C57BL/6 background. It was validated that CXCL11 KI mice expressed CXCL11 protein in dendritic cells, spleen and lung. CXCL11 KI mice were largely phenotypically indistinguishable from C57BL/6 mice, both at steady-state and during two models of viral infection. While CXCL11 expression did not modify acute antiviral responses, this study provides a new tool to understand the role of CXCL11 in other experimental settings.