C1q+ macrophages: passengers or drivers of cancer progression

International audienceThe omics era made possible the quest for efficient markers for cancer progression and revealed that macrophage populations are much more complex than just the M1/M2 dichotomy. Complement C1q pops up as a marker of a tolerogenic and immunosupressive macrophage populations in both healthy and tumor tissues, but the specific role of C1q+ tumor associated macrophages is poorly understood. C1q is co-expressed in healthy and tumor macrophages with HLA-DR, APOE and MRC1 (CD206), suggesting a resident origin of this population. Tumor associated macrophages expressing C1q correlate with T cell exhaustion and poor prognosis in numerous cancers. Herein, we discuss the plural roles of C1q in these macrophages and how it could drive cancer progression