Hee-Weon Lee

Sinigrin inhibits production of inflammatory mediators by suppressing NF-κB/MAPK pathways or NLRP3 inflammasome activation in macrophages.

&NA; Sinigrin (2‐propenyl glucosinolate) is found mainly in broccoli, brussels sprouts, and black mustard seeds. Recently, sinigrin has received attention for its role in disease prevention and health. This study investigated the effect of sinigrin on macrophage function, including the activity of Nod‐like receptor protein 3 (NLRP3) inflammasome. In a concentration‐dependent manner, sinigrin inhibited lipopolysaccharide (LPS)‐induced nitric oxide (NO) production and the expression of COX‐2 and prostaglandin E2 (PGE2) in RAW 264.7 cells. In addition, sinigrin significantly suppressed the production of tumor necrosis factor (TNF)‐&agr; and interleukin (IL)‐6 via suppression of MAPK phosphorylation and nuclear factor‐kappa B (NF‐&kgr;B) activity. Treatment with sinigrin decreased IL‐1&bgr; and IL‐18 production and concurrently suppressed NLRP3, apoptosis‐associated speck‐like protein containing a caspase recruitment domain (ASC), and caspase‐1 expression in LPS/ATP‐stimulated cells, suggesting that the blocking of NLRP3 inflammasome activation prevented the production of both cytokines. Collectively, these results suggest that sinigrin has immunomodulatory effects by suppressing the production of inflammatory mediators, possibly by inhibiting the NF‐&kgr;B/MAPK pathways or NLRP3 inflammasome activation. Our findings also provide evidence that the pharmacological modulation of sinigrin could have an anti‐inflammatory effect. HighlightsSinigrin inhibited LPS‐induced nitric oxide (NO) production and the expression of COX‐2 and PGE2.Sinigrin reduced TNF‐&agr; and IL‐6 production by inhibiting the NF‐&kgr;B/MAPK pathways.Sinigrin decreased IL‐1&bgr; and IL‐18 production via the blocking of NLRP3 inflammasome activation.

Inhibitory effect of sinigrin on adipocyte differentiation in 3T3-L1 cells: Involvement of AMPK and MAPK pathways

Adipocyte differentiation is a critical adaptive response to nutritional overload and affects the metabolic outcome of obesity. Sinigrin (2-propenyl glucosinolate) is a glucosinolate belong to the glucoside contained in broccoli, brussels sprouts, and black mustard seeds. We investigated the effects of sinigrin on adipogenesis in 3T3-L1 preadipocytes and its underlying mechanisms. Sinigrin remarkably inhibited the accumulation of lipid droplets and adipogenesis by downregulating the expression of CCAAT-enhancer-binding protein α (C/EBPα), peroxisome proliferator-activated receptor gamma (PPARγ), leptin and aP2. Sinigrin arrested cells in the G0/G1 phase of the cell cycle and increased the expression of p21 and p27. CDK2 expression was suppressed by sinigirn in MDI-induced adipocytes. Sinigrin increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK) and acetyl-CoA carboxylase (ACC) in the early stage of adipocyte differentiation, suggesting that sinigrin has anti-adipogenic effects through AMPK, MAPK and ACC activation. Sinigrin also inhibited the production of pro-inflammatory cytokines including tumor necrosis factor -alpha (TNF-α) and interleukin (IL)-6, IL-1β and IL-18. Taken together, these data suggest that sinigrin inhibits early-stage adipogenesis of 3T3-L1 adipocytes through the AMPK and MAPK signaling pathways.

Pneumolysin-induced autophagy contributes to inhibition of osteoblast differentiation through downregulation of Sp1 in human osteosarcoma cells

BACKGROUND INFORMATION The 53kDa protein pneumolysin (PLY) is the main virulence factor of Streptococcus pneumoniae, a leading cause of invasive pneumococcal diseases. PLY forms pores in cholesterol-containing membranes, thereby interfering with the function of cells. Bone destruction is a serious matter in chronic inflammatory diseases such as septic arthritis and osteomyelitis. S. pneumoniae is increasingly being recognized as a common cause of septic arthritis, but its pathogenesis is poorly defined. METHOD We examined the effect of PLY on osteoblast differentiation and its mechanisms of action. The effect of PLY on osteoblast differentiation was evaluated by qRT-PCR, ALP activity assay, flow cytometric analysis, and Western blotting. We also examined the role of PLY-induced autophagy in osteoblast differentiation using RNA interference analysis. RESULTS PLY inhibited osteoblast differentiation by decreasing the expression of osteoblast marker genes such as Runx2 and OCN, along with ALP activity. ROS production was increased by PLY during osteoblast differentiation. PLY induced autophagy through ROS-mediated regulation of AMPK and mTOR, which downregulated the expression of Sp1 and subsequent inhibition of differentiation. Treatment with autophagy inhibitors or Atg5 siRNA alleviated the PLY-induced inhibition of differentiation. CONCLUSION The results suggest that PLY inhibits osteoblast differentiation by downregulation of Sp1 accompanied by induction of autophagy through ROS-mediated regulation of the AMPK/mTOR pathway. GENERAL SIGNIFICANCE This study proposes a molecular mechanism for inhibition of osteoblast differentiation in response to PLY.