Analysis of tumor infiltrating immune cells in Kaposi sarcoma lesions discovers shifts in macrophage populations

Limited information exists about the types of immune cells present in Kaposi sarcoma (KS) lesions, especially in KS in the gastrointestinal tract. Using previously reported RNA-sequencing results from Kaposi sarcoma lesions in skin and gastrointestinal tract with normal matched tissues from the same patients at the same time, we investigated changes in lymphocytes in these tissues. We employed a computational method that determines changes in cell type distributions using KS lesion transcriptome data compared to a reference set of RNA expression patterns of purified immune cells. Since secreted cytokines and chemokines from KSHV-infected cells may influence the microenvironment of Kaposi sarcoma lesions, we performed cytokine profiling of conditioned media from KSHV-infected primary human dermal lymphatic endothelial cells. We also measured how this conditioned media altered the differentiation of macrophages in cell culture assays. These results suggested that factors in conditioned media from KSHV-infected endothelial cells promoted differentiation of a promonocytic cell line to proinflammatory macrophages.