Euglena gracilis paramylon activates human lymphocytes by upregulating pro‐inflammatory factors

Abstract

The aim of this study was to verify the activation details and products of human lymphomonocytes, stimulated by different β‐glucans, that is Euglena paramylon, MacroGard®, and lipopolysaccharide. We investigated the gene expression of inflammation‐related cytokines and mediators, transactivation of relevant transcription factors, and phagocytosis role in cell‐glucan interactions, by means of RT‐PCR, immunocytochemistry, and colorimetric assay. Our results show that sonicated and alkalized paramylon upregulates pro‐inflammatory factors (NO, TNF‐α, IL‐6, and COX‐2) in lymphomonocytes. A clear demonstration of this upregulation is the increased transactivation of NF‐kB visualized by immunofluorescence microscopy. Phagocytosis assay showed that internalization is not a mandatory step for signaling cascade to be triggered, since immune activity is not present in the lymphomonocytes that have internalized paramylon granules and particulate MacroGard®. Moreover, the response of Euglena β‐glucan‐activated lymphomonocytes is much greater than that induced by commercially used β‐glucans such as MacroGard®. Our in vitro results indicate that linear fibrous Euglena β‐glucan, obtained by sonication and alkaline treatment can act as safe and effective coadjutant of the innate immune system response.

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

“…It was well known that the pro-inflammatory cytokines secreted by immune cells play an important role in host defenses [14]. Paramylon extracted from E. gracilis has the ability to promote the production of TNF-α and IL-6 by human macrophages [34], and we confirmed the promotion of both mRNA and protein levels of cytokines in macrophages. Our study demonstrates that paramylon significantly induced TNF-α and IL-6 in RAW264.7 macrophages in a concentration-dependent manner ( Figure 4A, B).…”

“…It is clearly manifested in the paramylon increased transactivation of NF-κB visualized by immunofluorescence microscopy and detected the process of nuclei entering of NF-kB using the confocal microscope in this study [34]. However, the previous report did not have the false positive control (lipopolysaccharideinhibitor polymyxin B, PMB) as we did in this study to get rid of the potential pollution of LPS in paramylon [34]. Kankkunen [32].…”

“…We investigated the both NF-kB and MAPK pathways while only trans-activation of NF-kB was conducted in human cells [34]. We demonstrate that paramylon treatment also upregulates phosphorylation of IKK-β and IκB-α, resulting in increased phosphorylation of p65 ( Figure 4A).…”

Paramylon Treatment Improves Quality Profile and Drought Resistance in Solanum lycopersicum L. cv. Micro-Tom

“…This polysaccharide is a β-(1,3)-glucan endogenously synthetized as 1-2 µm granules consisting of 100% glucose [1]. The granules are composed of concentric segments, which possibly indicates the successive deposition of unbranched linear β-(1,3)-glucan chains on a central nucleus [2][3][4]. Wild type (WT) photosynthetic cells can accumulate paramylon up to 60% of cell dry weight (DW) [2], while the WZSL mutant of E. gracilis (spontaneous, non-chloroplastic, osmotrophic mutant; W describes the white color of the cells; Z means E. gracilis Klebs, Z strain; S means spontaneous mutant, and L means light grown parent culture) [5] can accumulate large amounts of it (up to 95% DW) when grown in the dark with an adequate carbon source [2].…”

“…β-1-3-glucan purified from the WZSL mutant is further processed to produce linear nanofibers suited for binding to Dectin-1 receptors of target cell membranes. The effect of these nanofibers has been already investigated in our laboratory on tomato plants, animals, and humans [4,[15][16][17]. In tomatoes, paramylon nanofibers modulate conductance to carbon dioxide (CO 2 ) diffusion from air to the carboxylation sites by regulating hormone levels and water-use efficiency, leading to an increase of plant defense capacity against drought [16].…”