The Immunomodulatory Role of G2013 (α-L-Guluronic Acid) on the Expression of TLR2 and TLR4 in HT29 cell line.

BACKGROUND: The non-steroidal anti-inflammatory drugs (NSAIDs) play crucial role in the controlling of inflammatory diseases. Due to the vast side effects of NSAIDs, its use is limited. G2013 or α-L-Guluronic Acid is a new NSAID with immunomodulatory features. OBJECTIVES: Considering the leading role of TLRs in inflammatory responses, in this study, we aimed to evaluate G2013 cytotoxicity and its effect on the expression of TLR2 and TLR4 molecules. METHODS: HEK293-TLR2 and HEK293-TLR4 cells were cultured and seeded on 96-well cell plate, and MTT assay was performed for detecting the viability of the cells after treatment with different concentrations of G2013. HT29 cells were grown and treated with low and high doses of G2013. After total RNA extraction and cDNA synthesis, quantitative real-time PCR were performed to assess the TLR2 and TLR4 mRNA synthesis. RESULTS: We found that concentrations of ≤125 µg/ml of G2013 had no apparent cytotoxicity effect on the HEK293-TLR2 and -TLR4 cells. Our results indicated that after G2013 treatment (5 µg/ml) in HT29 cells, TLR2 and TLR4 mRNA expression decreased significantly compared with the untreated control group (p=0.02 and p=0.001 respectively). CONCLUSION: The results of this study revealed that G2013 can down regulate the TLR2 and TLR4 gene expression and exerts its inhibitory effect. Our findings are parallel to our previous finding which showed G2013 ability to down regulate the signaling pathway of TLRs. However, further studies are needed to identify the molecular mechanism of G2013.

Immunomodulatory Effect of G2013 (α-L-Guluronic Acid) on the TLR2 and TLR4 in Human Mononuclear Cells.

BACKGROUND: Inhibition of Toll-like receptors (TLRs) signaling has been established as a new method for the development of anti-inflammatory drugs instead of NSAIDs (non-steroid anti-inflammatory drugs). Since the immunomodulatory role of G2013 (α-L-Guluronic acid) was reported in some recent experiments, we decided to assess the effects of G2013 on the protein expression of TLR2 and TLR4, their downstream signaling cascade, and the secretion of pro-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs). METHODS: After blood sampling from 16 healthy donors, PBMCs were isolated and treated with/without lipopolysaccharide (LPS), lipopolyteichoic acid (LTA), and G2013. Flow cytometry was done for detecting the protein expression of TLR2 and TLR4. MyD88, IκB, Tollip, and NF-κB mRNA expression were assessed by realtime PCR. ELISA was performed for assessing the concentration of IL-1ß and IL-6. RESULTS: G2013 at a concentration of 25 µg/mL (high dose) significantly downregulated NF-κB, IκB and MyD88 mRNA expression and suppressed the secretion of IL-1ß by PBMCs. The findings indicate that G2013 may exert its regulatory effect under normal condition via Tollip in a dose dependence pathway. Our results demonstrated that G2013 had no profound impact on the protein expression of TLR2 and TLR4. CONCLUSION: In conclusion, our findings point to the immunomodulatory effect of G2013 on the TLR2 and TLR4 signaling cascade and cytokine production by PBMCs. These findings could lead to an establishment of new safe anti-inflammatory drugs in the future.