Although various derivatives of caffeic acid have been reported to possess a wide variety of biological activities such as neuronal protection against excitotoxicity and anti-inflammatory property, the biological activity of 3,4,5-trihydroxycinnamic acid (THC), a derivative of hydroxycinnamic acids, has not been clearly examined. The objective of the present study is to evaluate the anti-inflammatory effects of THC on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. THC significantly suppressed LPS-induced excessive production of nitric oxide (NO) and expression of iNOS, which is responsible for the production of iNOS. THC also suppressed LPS-induced overproduction of pro-inflammatory cytokines such as IL-1β and TNF-α in BV2 microgilal cells. Furthermore, THC significantly suppressed LPS-induced degradation of IκB, which retains NF-κB in the cytoplasm. Therefore, THC attenuated nuclear translocation of NF-κB, a major pro-inflammatory transcription factor. Taken together, the present study for the first time demonstrates that THC exhibits anti-inflammatory activity through the suppression of NF-κB transcriptional activation in LPS-stimulated BV2 microglial cells.

NF-E2-related factor 2 (Nrf2) has been demonstrated to be a key transcription factor regulating the anti-inflammatory genes including heme oxygenase-1 (HO-1) in experimental sepsis models. Based on the fact that 3,4,5-trihydorxycinnamic acid (THC) has been reported to possess anti-inflammatory properties in BV2 microglial cells, the possible effects of THC and its underlying mechanism was examined against lipopolysaccharide (LPS)-induced RAW 264.7 cell culture and septic mouse models. Pretreatment of RAW 264.7 cells with THC significantly attenuated LPS-induced NO, PGE2 production, and expression of iNOS and COX-2. THC also significantly suppressed LPS-induced release of pro-inflammatory cytokines and degradation of IκB-α. Increased phosphorylation of Nrf2 and nuclear translocation of Nrf2 were observed with THC treatment with consequent expression of HO-1. The data demonstrated that multiple signaling pathways including Akt, p38, and PKC are involved in the THC-induced activation of Nrf2/HO-1 pathway. Treatment of THC resulted in significantly increased survival of LPS-induced septic mice. THC also significantly ameliorated LPS-induced septic features such as hypothermia and increased vascular leakage. In accordance with the data from cell culture model, THC exhibited increased expression of HO-1 in kidney and decreased serum level of pro-inflammatory mediators such as TNF-α, IL-1β, and NO. Taken together, the present study for the first time demonstrates that THC inhibits inflammation in LPS-induced RAW264.7 cells by Nrf2 activation and improves survival of mice in LPS-induced endotoxemia model.

Quercetin, a flavonol, has been reported to exhibit a wide range of biological properties including anti-oxidant and anti-inflammatory activities. However, pharmacological properties of quercetin-3-O-β-D-glucuronide (QG), a glycoside derivative of quercetin, have not been extensively examined. The objective of this study is to elucidate the anti-inflammatory property and underlying mechanism of QG in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells in comparison with quercetin. QG significantly suppressed LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and PGE2, and pro-inflammatory protein expressions of iNOS and COX-2. To elucidate the underlying mechanism of the anti-inflammatory property of QG, involvement of MAPK signaling pathways was examined. QG significantly attenuated LPS-induced activation of JNK and ERK in concentration-dependent manners with a negligible effect on p38. In conclusion, the present study demonstrates QG exerts anti-inflammatory activity through the suppression of JNK and ERK signaling pathways in LPS-challenged RAW264.7 macrophage cells.

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Neurofi brillary tangles (NFTs) of microtubule-associated protein tau are a pathological hallmark of Alzheimer's disease (AD). Endoplasmic reticulum (ER) stress has been known to be involved in the pathogenesis of AD. However, the exact role of ER stress in tau pathology has not yet been clearly elucidated. In present study, the possible relationship between tau pathology and ER stress was examined in terms of sorcin, which is a calcium binding protein and plays an important role in calcium homeostasis. Our previous yeast two hybrid study showed that sorcin is a novel tau interacting protein. Caspase-3-cleaved tau (T4C3) showed significantly increased tau-sorcin interaction compared to wild type tau (T4). Thapsigargin-induced ER stress and co-expression of constitutively active GSK3β (GSK3β-S9A) also exhibited significantly increased tau-sorcin interactions. T4C3-expressing cells showed potentiated thapsigargin-induced apoptosis and disruption of intracellular calcium homeostasis compared to T4-expressing cells. Overexpression of sorcin signifi cantly attenuated thapsigargin-induced apoptosis and disruption of calcium homeostasis. In contrary, siRNA-mediated knock-down of sorcin showed significantly increased thapsigargin-induced apoptosis and disruption of calcium homeostasis. These data strongly suggest that sequestration of sorcin by aberrant forms of tau compromises the function of sorcin, such as calcium homeostasis and cellular resistance by ER stress, which may consequently result in the contribution to the progression of AD.