Cancer cells in Hodgkin's lymphoma [HL] account for only a few % of the tumor mass which mainly consists of normal cells of the immune system including macrophages. Macrophages may perform different functions depending on the signals they receive. Tumor-associated macrophages (TAM) are often polarized towards the M2-like phenotype - immunosuppressive phenotype, preferring oxygen metabolism, and their presence in HL is associated with a worse prognosis. HL is highly avid in positron emission tomography, which suggests that glucose (Glc) metabolism is increased in non-cancerous microenvironmental cells. Here we asked if and what type of glucose metabolism is increased in TAMs and monocytes/Cd14+ cells. The project was conducted on the in vitro and the ex vivo model. In the in vitro model, the studied populations were THP-1 monocytic macrophages stimulated by Reed-Sternberg [RS] cells, and control macrophages that were not subjected to stimulation. In the ex vivo model, CD14+ cells were isolated, using the immunomagnetic method, from: fine-needle biopsy lymph node aspirate, peripheral blood of patients diagnosed with HL and from peripheral blood of a healthy donor. The cell’s phenotype was determined by flow cytometry using CD14, CD16, CD163, CD206, CD68, CD11b, HLA-DR, PDL1 antibodies. Glc metabolism of the studied cell populations was analyzed using the Seahorse XFp analyser [by directly measuring the extracellular acidification rate (ECAR) and the oxygen consumption rate (OCR)]. The in vitro model experiment showed the intensification of Glc metabolism, in both glycolysis and oxidative phosphorylation pathways, in cells that have been stimulated by RS cells compared to control macrophages. Comparable results were obtained in the ex vivo model, which corroborates the reliability of the in vitro model. Glucose metabolism increases not only the population of cells obtained from lymph node aspirate but also from peripheral blood of patients diagnosed with HL, which may indicate both paracrine and endocrine neoplastic cells impact. Our data indicate that RS cells stimulate Glc metabolism of tumor microenvironment and peripheral blood CD14+ cells through both glycolysis and oxidative phosphorylation pathways.
Michał Kurlapski, Maciej Szydłowski, Alicja Braczko, Marika Frańczak, Maciej Zieliński, Ryszard Smoleński, Przemysław Juszczyński, Jan Maciej Zaucha