Immune activation of murine RAW264.7 macrophages by sonicated and alkalized paramylon from Euglena gracilis

Abstract

Background: Euglena is a new super health food resource that is rich in the natural polysaccharide paramylon, a linear β-1,3-glucan with various biological activities including activity on the immune system in different cell lines and animals. Despite these reports, the immune regulation mechanism of paramylon is still unclear. Results: We investigate the signaling pathways paramylon impacts in immune macrophages. In RAW264.7 macrophages, sonicated and alkalized paramylon oligomers up-regulated inducible nitric oxide synthase (iNOS) and increased secretion of nitric oxide (NO), interleukin (IL)-6 and tumor necrosis factor (TNF)-α, in a concentration-dependent manner. In addition, paramylon activated the nuclear factor-κB(NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways and inhibiting these pathways attenuated the paramylon-induced secretion of the above immune-mediators. Conclusions: These results demonstrate that Euglena gracilis paramylon modulates the immune system via activation of the NF-κB and MAPK signaling pathways and thus has potential therapeutic benefits.

Prebiotic activity of paramylon isolated from heterotrophically grown Euglena gracilis

“…The paramylon itself is a recalcitrant substrate, however different pretreatment methods have been reported to obtain soluble β-1, 3-glucans ( Gissibl et al., 2019 , Kusmic et al., 2018 ). The paramylon treatment with sodium hydroxide is known to reduce the degree of polymerization ( Guo et al., 2020 ) and also yield soluble nanofibers ( Kataoka et al., 2002 ). These soluble nanofibers have been shown to enhance stimulation of leucocytes and hepatoprotection because of the formation of more bioactive single helices ( Kusmic et al., 2018 ).…”

“…These soluble nanofibers have been shown to enhance stimulation of leucocytes and hepatoprotection because of the formation of more bioactive single helices ( Kusmic et al., 2018 ). In a recent study, alkali treated paramylon has been shown to activate the immuneresponse in murine RAW264.7 cells ( Guo et al., 2020 ). The SEM of soluble paramylon clearly depicts the opening of the paramylon granules ( Figure 3 ).…”