ISHL10 Abstract T008

CCR5 blocking by Maraviroc inhibited recruitment, proliferation and pro-tumor effects of mesenchymal stromal cells and monocytes in 2D and 3D models of Hodgkin Lymphoma microenvironment

In classical Hodgkin Lymphoma (cHL), the tumor microenvironment (TME) is dominated by an extensive mixed cellular inflammatory infiltrate that plays a decisive role in the pathobiology of the disease. CCL5 and its main receptor CCR5, expressed by cHL cells and by bystander cells including stromal cells and macrophages, are increased in cHL lymph nodes respect to normal lymph nodes. Recently, CCL5 and CCR5 have been implicated in cancer progression. Our hypothesis is that CCL5 secreted by cHL cells could recruit Mesenchymal Stromal cells (MCS) and monocytes, which in turn educated by tumor cells may affect tumor progression. To demonstrate the involvement of CCL5 in the cross-talk of cHL cells with the TME we used neutralizing anti-CCL5 antibody and the CCR5 antagonist Maraviroc. We found that CCL5 secreted by L-1236, L-428, KM-H2 and HDLM-2 cHL cell lines, recruited and increased the proliferation of MSCs from Bone Marrow and Adipose Tissue. In turn, tumor-educated MSCs (E-MSCs) secreted higher amounts of CCL5, which increased the proliferation, the clonogenic growth and the movement/spread of cHL cells. Both E-MSCs and cHL cells by secreting CCL5 were able to recruit monocytes purified from Peripheral blood, suggesting that monocytes may be recruited directly by tumor cells and indirectly by E-MSCs. Treatment of monocytes with L-1236-conditioned medium (CM) enhanced the surface expression of CCR5, the proliferation and induced the secretion of CCL5. In turn, tumor-educated monocytes, by secreting CCL5, increased the proliferation and the clonogenic growth of L-1236 and HDLM2 cells. Only CM from tumor-educated monocytes inhibited the proliferation of PHA activated peripheral blood mononuclear cells. Finally, using a new tridimensional (3D) approach (mixed organoids) to mimic the TME, we found that the cocultivation of L1236 and HDLM-2 cells with monocytes, MSCs and especially the combination cHL/monocytes/MSCs increased the survival/proliferation of tumor cells. Treatment with Maraviroc not only decreased cHL cell survival/proliferation due to the cocultivation with MSCs and monocytes, but also disrupted the 3D mixed organoids. Taken together our results suggest that CCL5 secreted by cHL cells, as well as by tumor-educated MSCs and monocytes, may build the protective TME and suggest a potential for Maraviroc as adjuvant therapy to block TME formation and tumor cell proliferation due to CCR5 ligands.