title: Tumour cell derived effects on monocyte/macrophage polarization and function and modulatory potential of Viscum album lipophilic extract in vitro.
abstract: BACKGROUND
  Macrophages are highly versatile cells that play an important role in tumour microenvironment. Tumour associated macrophages (TAMs) have been linked to both, good or bad prognosis of several cancer types depending on their number, composition and polarization. Viscum album lipophilic extract (VALE) contains several pentacyclic triterpenes known to modulate the activity of monocytes and other immune cells and to exhibit anticancer properties. In our in vitro study, we investigated the effect of tumour cell lines on macrophage polarization and monocyte chemotactic transmigration and examined the modulatory potential of VALE and its predominant triterpene oleanolic acid (OA).
  
  
  METHODS
  Human peripheral blood monocytes were differentiated into monocyte derived macrophages (MDM) using M-CSF and polarized into M1 by IFN-γ and LPS and into M2 macrophages by IL-4 and IL-13 or by co-culture with two different tumour cell lines. Polarized macrophages were subsequently treated with VALE or OA. Phenotypic markers and cytokines were assessed by flow cytometry and immunoanalysis. Migration of human peripheral blood monocytes induced by monocyte chemotactic protein-1 (MCP-1) or supernatants of different tumour cell lines under the influence of VALE or OA was measured in a chemotaxis transmigration assay.
  
  
  RESULTS
  In vitro polarized M1 and M2 type macrophages revealed specific phenotypic patterns and tumour cell co-cultured MDM displayed ambiguous phenotypes with M1 as well as M2 associated markers. VALE and OA showed modest influence on cell surface marker profile and cytokine expression of tumour cell co-cultured macrophages. All tumour cell supernatants markedly enhanced the migratory activity of monocytes. VALE and OA significantly inhibited MCP-1 induced monocyte transmigration, whereas monocyte migration initiated by tumour cell derived supernatants was not affected.
  
  
  CONCLUSIONS
  In our study we reconfirmed that co-culture with different tumour cell lines can result in a mixed macrophage phenotype with M1 as well as M2 patterns, a finding that is important for a better understanding of tumour microenvironment functions. Moreover, we demonstrated that VALE shows slight immunomodulatory effects on tumour cell co-cultured macrophages and modulates monocyte chemotactic transmigration in vitro, indicating promising possibilities of triterpenes from Viscum album L. to contribute in a multimodal concept of anti-cancer therapy in future. Our data contribute to an understanding of monocyte function and macrophage polarization in vitro and of the possibility to influence their behaviour by triterpene containing mistletoe extracts.
authors.affiliation: Witten/Herdecke University, 58448, Witten, Germany. myriam.estko@uni-wh.de.
authors.forename: Myriam
authors.initials: M
authors.lastname: Estko
authors.affiliation: Society for Cancer Research, Hiscia Institute, 4144, Arlesheim, Switzerland. s.baumgartner@vfk.ch.|Institute of Integrative Medicine, Witten/Herdecke University, 58448, Witten, Germany. s.baumgartner@vfk.ch.
authors.forename: Stephan
authors.initials: S
authors.lastname: Baumgartner
authors.affiliation: Society for Cancer Research, Hiscia Institute, 4144, Arlesheim, Switzerland. k.urech@vfk.ch.
authors.forename: Konrad
authors.initials: K
authors.lastname: Urech
authors.affiliation: Society for Cancer Research, Hiscia Institute, 4144, Arlesheim, Switzerland. m.kunz@vfk.ch.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kunz
authors.affiliation: Society for Cancer Research, Hiscia Institute, 4144, Arlesheim, Switzerland. u.regueiro@vfk.ch.
authors.forename: Ursula
authors.initials: U
authors.lastname: Regueiro
authors.affiliation: Institute of Integrative Medicine, Witten/Herdecke University, 58448, Witten, Germany. peter.heusser@uni-wh.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Heusser
authors.affiliation: Society for Cancer Research, Hiscia Institute, 4144, Arlesheim, Switzerland. u.weissenstein@vfk.ch.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Weissenstein
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D018932:Chemokine CCL2 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D018793:Interleukin-13 / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects*; D009000:Monocytes / Q000187:drug effects*; D009369:Neoplasms / Q000378:metabolism*; D009828:Oleanolic Acid / Q000494:pharmacology*; D010641:Phenotype; D010936:Plant Extracts / Q000494:pharmacology*; D028182:Viscum album / Q000737:chemistry*
chemical_list: D015415:Biomarkers; C111835:CCL2 protein, human; D018932:Chemokine CCL2; D016207:Cytokines; D018793:Interleukin-13; D010936:Plant Extracts; D015847:Interleukin-4; D009828:Oleanolic Acid; D016173:Macrophage Colony-Stimulating Factor