381-389C-phycocyanin (C-pc), a fluorescent protein purified from the blue-green algae, Spirulina fusiformis, is reported to possess anti-inflammatory activity. Employing in vitro experiments and in vivo mouse models, we had earlier demonstrated the wound healing property of C-pc. In the current study, we evaluated the influence of C-pc on M1/M2 polarization of resting (M0) macrophages, using RAW 264.7 macrophage cells. Incubation of macrophages with C-pc resulted in upregulation of M1 markers (iNOS, IL-1β, IL-6 and TNF-α), and generation of reactive oxygen species and nitric oxide. In contrast, M2 markers, IL-10 and Arginase-1, exhibited reduced expressions. Immunoblotting and immunofluorescence studies revealed the activation and nuclear translocation of p65- NF-ĸB and JNK proteins. Inhibition studies showed that NF-ĸB and JNK were instrumental in shifting the polarization of M0 macrophages towards pro-inflammatory phenotype. NF-ĸB was responsible for the increase in TNF-α, IL-1β, and iNOS. JNK was responsible for the effect on IL-1β, IL-6 and Arg-1. This is the first report on the influence of NF-ĸB and JNK in mediating the pro-inflammatory action of C-pc, which could help towards phagocytosis and antimicrobial activity, processes required during the initial phases of wound healing. This study also exposes the biphasic action of C-pc towards modulating inflammatory processes
