CD163+ macrophages in mantle cell lymphoma induce activation of pro-survival pathways and immune suppression.

Mantle cell lymphoma (MCL) is dependent on a supportive tumor immune microenvironment (TIME), where infiltration of CD163+ macrophages has a negative prognostic impact. This study explores how abundance and spatial localization of CD163+ cells are associated with the biology of the MCL TIME. This is achieved through spatial multi-omic investigations of tumor and infiltrating CD163+ and CD3+ cells, respectively. We analyzed diagnostic MCL tissue from 100 patients. Sixty-three proteins were measured by GeoMx® digital spatial profiling in tissue microarrays. Regions of interests (ROIs) were selected in tumor-rich and tumor-sparse tissue regions. Molecular profiling of CD163+ macrophage segments, CD20+ MCL tumor cell segments and CD3+ T-cell segments was performed. To validate protein profiles, 1811 mRNAs were measured in CD20+ cells and two subsets of T-cells. Image analysis was used to extract the phenotype and position of each targeted cell allowing exploration of cell frequencies and cellular neighborhoods. Proteomic investigations revealed that CD163+ cells modulate their immune profile depending on the localization and that the immune inhibitory molecules VISTA and B7-H3 have higher expression in tumor-sparse versus tumor-rich tissue regions and targeting should be explored. We show that MCL tissues with more abundant infiltration of CD163+ cells have a higher expression of key components of the mitogen-activated protein kinase (MAPK) pathway, which was validated by complementary mRNA analyses. Thus, the MAPK pathway may be a feasible therapeutic target in MCL patients with CD163+ cell infiltration. We further show the independent and combined prognostic value of CD11c and CD163 beyond established risk factors.