<i>Euglena gracilis</i> 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 <i>β</i>-glucans, that is <i>Euglena</i> 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-<i>α</i>, 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 <i>Euglena β</i>-glucan-activated lymphomonocytes is much greater than that induced by commercially used <i>β</i>-glucans such as MacroGard^®. Our <i>in vitro</i> results indicate that linear fibrous <i>Euglena β</i>-glucan, obtained by sonication and alkaline treatment can act as safe and effective coadjutant of the innate immune system response.