Sulfur Compounds Inhibit High Glucose-Induced Inflammation by Regulating NF-κB Signaling in Human Monocytes
Eun Seong Jo | Nipin Sp | Dong Young Kang | Alexis Rugamba | Il Ho Kim | Se Won Bae | Qing Liu | Kyoung-Jin Jang | Young Mok Yang
High glucose-induced inflammation leads to atherosclerosis, which is considered a major cause of death in type 1 and type 2 diabetic patients. Nuclear factor-kappa B (NF-&kappa:B) plays a central role in high glucose-induced inflammation and is activated through toll-like receptors (TLRs) as well as canonical and protein kinase C-dependent (PKC) pathways. Non-toxic sulfur (NTS) and methylsulfonylmethane (MSM) are two sulfur-containing natural compounds that can induce anti-inflammation. Using Western blotting, real-time polymerase chain reaction, and flow cytometry, we found that high glucose-induced inflammation occurs through activation of TLRs. An effect of NTS and MSM on canonical and PKC-dependent NF-&kappa:B pathways was also demonstrated by western blotting. The effects of proinflammatory cytokines were investigated using a chromatin immunoprecipitation assay and enzyme-linked immunosorbent assay. Our results showed inhibition of the glucose-induced expression of TLR2 and TLR4 by NTS and MSM. These sulfur compounds also inhibited NF-&kappa:B activity through reactive oxygen species (ROS)-mediated canonical and PKC-dependent pathways. Finally, NTS and MSM inhibited the high glucose-induced expression of interleukin (IL)-1&beta:, IL-6, and tumor necrosis factor-&alpha: and binding of NF-&kappa:B protein to the DNA of proinflammatory cytokines. Together, these results suggest that NTS and MSM may be potential drug candidates for anti-inflammation therapy.
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