M2 macrophage polarization assay for in vitro assessment of drug ability to relieve immunosuppressive features
07 / 22 / 2020
Unlike M1 macrophages which promote a pro-inflammatory response, alternatively activated M2 macrophages, with diametrically opposed functions, trigger inflammation resolution and suppress T cell activation via several mechanisms including release of anti-inflammatory cytokines, immune checkpoint engagement, and metabolic activities involving arginase 1 and indoleamine 2,3-dioxygenase, for instance, which promote essential amino acid – arginine and tryptophan, respectively – depletion. Such M2-related markers are the main features shared with the so-called tumor-associated macrophages (TAMs).
Immunosuppressive M2 macrophage phenotype is relieved by PI3K signaling inhibition.
(A) Phenotypic IL10high IL6low M2-associated status is dose-dependently reversed by a PI3K signaling inhibitor. HTRF-based quantification of IL10 and IL6 levels released in the supernatants of M2 macrophages in untreated controls or following treatment with LY294002 (PI3K inhibitor) during M2 polarization.
(B, C) Arginine and tryptophan catabolic activities are dose-dependently lowered by a PI3K signaling inhibitor. ELISA-based quantification of L-Arginine (B, using IS-I-0400 kit), L-Tryptophan and L-Kynurenine levels (C, using BA-E-2700 and BA-E-2200 kits, respectively) in the supernatants of M2 macrophages in untreated controls or following treatment with LY294002 during M2 polarization.