INTRODUCTION: Glioblastoma (GBM) reprograms glioma-associated microglia/macrophages (GAMs) toward tumor-supporting states. SorLA is an intracellular sorting receptor that limits microglial inflammatory activity, yet its role in immune signaling remains unclear. Based on our proteomics data from wild-type (WT) and SorLA-deficient (SorLA-KO) microglia co-cultured with glioma cells, we hypothesise that SorLA regulates interferon-γ (IFNγ) responses in brain myeloid cells.

AIM(S):

METHOD(S): We used RT-qPCR to analyze expression levels of interferon-regulated genes in sorted CD11b⁺ cells from gliomas in WT and SorLA-deficient mice. To assess the impact of SorLA loss on IFNγ signaling, we generated a SorLA-KO RAW264.7 macrophage line using CRISPR/Cas9. We used this newly established cell line and primary microglia cultures to investigate cellular responses to IFNγ, quantifying STAT1 phosphorylation and its nuclear translocation, and the expression of IFNγ target genes.

RESULTS: SorLA deficiency altered the proteome of primary microglia co-cultured with glioma cells. SorLA-KO microglia was characterized by higher abundance of interferon-induced and phagocytosis-related proteins. Further studies confirmed that SorLA-KO microglia showed increased phagocytosis. RT-qPCR of sorted CD11b⁺ cells revealed a pro-inflammatory shift of SorLA-KO cells, with reduced expression of the markers of tumor-supportive phenotype (CD163, CD206, Arg1) and increased interferon-inducible genes (IFIT1, IFIT2). Currently we are investigating responses to both genotypes to IFNγ in cellular models.

CONCLUSIONS: Together, our data suggest that SorLA may act as a modulator of IFNγ-dependent signaling in microglia/macrophages, linking intracellular sorting to neuroinflammatory responses. This mechanism may have relevance for shaping the properties of the brain microenvironment in glioblastoma.

FINANCIAL SUPPORT: This research was supported by the NCN OPUS research grant 2020/37/B/NZ3/00761