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

The aim of this study was to verify the activation details and products of human lymphomonocytes, stimulated by different beta-glucans, that is Euglena paramylon, MacroGard (R), 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-alpha, 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 (R). Moreover, the response of Euglena beta-glucan-activated lymphomonocytes is much greater than that induced by commercially used beta-glucans such as MacroGard (R). Our in vitro results indicate that linear fibrous Euglena beta-glucan, obtained by sonication and alkaline treatment can act as safe and effective coadjutant of the innate immune system response.