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.

Metabolic Responses of a Model Green Microalga Euglena gracilis to Different Environmental Stresses

“…The total algal chlorophyll was extracted with 95% ethanol, and the content was spectrophotometrically assayed according to the method (Harris, 2009;Smith, 2009). The paramylon of 5 × 10 7 -10 8 cells was extracted and measured as described previously (Sugiyama et al, 2009;Nakazawa et al, 2017;Guo et al, 2020). The total lipids of 10 7 -10 8 cells were measured using the oven-drying method (Yang et al, 2018).…”

Recent Advancements and Future Perspectives of Microalgae-Derived Pharmaceuticals

“…Based on this, paramylon is already marketed as an immunostimulatory agent in nutraceuticals. Beta-glucan from Euglena algae is a new immune-support ingredient, as the naturally occurring beta-glucan content is recognized explicitly by immune cell receptors [88]. Preclinical and clinical studies support the positive effects of this microalga and its beta-glucan content on multiple aspects of immunity [87].…”

Prebiotic activity of paramylon isolated from heterotrophically grown Euglena gracilis

“…These soluble nanofibers have been shown to enhance stimulation of leucocytes and hepatoprotection because of the formation of more bioactive single helices (Kusumic 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).…”

“…The paramylon itself is a recalcitrant substrate, however different pretreatment methods have been reported to obtain soluble β-1, 3-glucans (Gissibl et al, 2018, Kusumic et al, 2018. The paramylon treatment with sodium hydroxide is known to reduce the degree of polymerization J o u r n a l P r e -p r o o f (Guo et al, 2020) and also yield soluble nanofibers (Katoka 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 (Kusumic et al, 2018).…”