The anti-inflammatory effects of sialic acid on the human glia cells by the upregulation of IL-4 and IL-10 genes' expressions

Abstract

Glioblastoma multiform (GBM) creates an immunosuppressive microenvironment to escape from immune response. GBM evades the immune system by the secretion of immune inhibiting molecules. On the other hand, some cytokines such as interleukin 4 and 10 by having anti-inflammatory property play important roles in the metastasis, cell proliferation, and the apoptosis prevention. Recent studies have shown that increasing the sialic acid concentration on the tumor cell surface might consequently increase metastasis. Thereby, in this study, we aimed to investigate the correlation between the increased sialic acid concentration and the gene expressions of interleukine-4 (IL-4) and interleukine-10 (IL-10). To do this, we used the lipopolysaccharide (LPS) as a known trigger of cell inflammation in comparison with sialic acid, in order to bring more transparency regarding the effect of sialic acid as a potent anti-inflammatory agent. In addition, we used the human glial cell line (1321N1) treated with different concentrations of the sialic acid and the LPS. Real-time PCR was used to assess the expression levels of IL-4 and IL-10.We showed that the expressions of the IL-4 and the IL-10 genes were upregulated by increasing sialic acid concentration compared to the control group. Conversely, the cells treated by the LPS have shown the down-regulation of IL-4 and IL-10 genes' expressions. According to the results, sialic acid can positively affect the expression of specific interleukins by enhancing anti-inflammatory factors. In this context, LPS is a contra player of sialic acid, which causes the down-regulation of IL-4 and IL-10 cytokines.