Objective: Advanced glycation end products (AGEs), such as N ε -(carboxymethyl)-lysine (CML), modified proteins activate macrophages and increase the production of inflammatory cytokines via receptors for advanced glycation end products (RAGE) mediated pathway. These compounds ultimately lead to the progress of acute and chronic inflammatory diseases like rheumatoid arthritis, knee osteoarthritis, locomotive syndrome and so on. Therefore, to suppress the upregulation of inflammatory gene

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... ion is helpful way in both prevention and cure. Melatonin secretion declines with age, whereas AGE production and accumulation increases. In this study, we examined the effect of melatonin on CML-HSA (human serum albumin)-induced inflammatory gene expression in RAW264.7 cells. Methods: The mouse macrophage cell line RAW264.7 were treated with 10 and 0.1 μg/mL melatonin or 2 μL/mL dimethyl sulfoxide (DMSO) as the vehicle control for 24 hours, followed by stimulation by 0.5 μg/mL CML-HSA for 3 hours. TNFα protein content was analyzed by enzyme-linked immunosorbent assay (ELISA) and the inflammatory gene mRNA expression was measured by real-time polymerase chain reaction (RT-PCR). Cell viability was determined using a cell counting kit-8 (CCK-8) and lactate dehydrogenase (LDH) assay. Results: TNFα secretion was significantly elevated by CML-HSA stimulation for 3 hours (p < 0.001). Pretreatment with melatonin did not inhibit TNFα production, TNFα, RAGE, inducible nitric oxide synthase (iNOS), interleukin-1 beta (IL-1β), or IL-6 mRNA expression. Cell viability was not affected by the experimental conditions. Conclusion: These data suggested that melatonin does not have any inhibitory or stimulatory effect on CML-HSA-induced (glycative stress-induced) inflammatory gene expression in RAW264.7 cells. Melatonin has no direct effect on inflammatory gene expression in CML-HSA stimulated RAW264.7 cells N ε -(carboxymethyl)-lysine (CML) is a major antigenic AGE which can activate RAGE-mediated reactive oxygen species (ROS), MAP kinase and nuclear factor-kappa B (NF-KB), ultimately leading to inflammatory cytokine formation 8) . Increased CML levels are observed in the cerebral blood vessels of both diabetic patients and in the streptozotocin-treated rat model of diabetes mellitus 9) . These evidences indicate that CML contributes to diabetes complications. CML has been identified in synovial tissue of rheumatoid arthritis (RA) patients, and presumably causes the perpetuation of inflammation in the joint 10) . In obese subjects, CML accumulation in adipose tissue, as evidenced by the decreased plasma levels of CML, plays an important role in adipose tissue inflammation 11) .