16α, 17α-epoxypregnenolone-20-oxime inhibits NO and IL-6 production in LPS-treated RAW264.7 cells

Abstract

Abstract. It has previously been repor ted t hat 16α, 17α-epoxypregnenolone-20-oxime (EPREGO) exerts an inhibitory effect on nitric oxide (NO) production and inducible NO synthase (iNOS) expression in microglia. The present study aimed to investigate the effects of EPREGO on the lipopolysaccharide (LPS)-induced inflammatory response in RAW264.7 macrophage cells, and to determine the underlying molecular mechanisms using western blot analysis, enzyme-linked immunosorbent assays and fluorescence-activated cell sorting. The present study demonstrated that LPS-induced production of NO and interleukin (IL)-6, and the protein expression levels of iNOS, were reduced by EPREGO in a dose-and time-dependent manner, whereas, EPREGO did not affect tumor necrosis factor-α production. In addition, EPREGO suppressed LPS-induced cellular reactive oxygen species production and phagocytosis. Furthermore, EPREGO significantly inhibited the LPS-induced activation of mitogen-activated protein kinases and inhibitor of κB α degradation in LPS-stimulated RAW264.7 cells, thus resulting in modulation of the production of NO and IL-6. Taken together, these results suggest that EPREGO exhibits anti-inflammatory activity in macrophages, thus validating the hypothesis that EPREGO may be useful as a therapeutic agent for the treatment of macrophage-mediated inflammation. IntroductionMacrophages, which are critical effector cells, contribute to the innate immune response against infection. Macrophages are considered the most efficient pathogen scavengers, and are the main source of proinflammatory mediators and cytokines, including nitric oxide (NO), interleukin (IL)-6 and tumor necrosis factor (TNF)-α. Proinflammatory mediators are essential for inducing inflammation at the site of infection and for fighting pathogenic infections (1,2). However, the excessive production of proinflammatory cytokines has severe consequences, including tissue damage and septic shock (3,4). Therefore, suppressing the synthesis or release of proinflammatory cytokines and mediators is a potential therapeutic strategy for the treatment of septic shock-like diseases associated with inappropriately amplified inflammation.Several intracellular signaling pathways, including the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways, are activated in lipopolysaccharide (LPS)-induced macrophages, and regulate inflammatory actions and immune responses. In macrophages, the MAPK signaling pathway is one of the most extensively investigated intracellular signaling cascades involved in the LPS-induced inflammatory response (5-8). The MAPK pathway is comprised of at least three signaling components: Extracellular signal-regulated kinases 1/2 (ERK 1/2); c-Jun N-terminal kinase (JNK); and p38 MAPK, all of which have been demonstrated to induce the release of immune-related cytotoxic factors and proinflammatory cytokines (9-11). Furthermore, NF-κB is important for controlling innate and adaptive immunity, and for regulating the expression of various genes d...

FcγRIIb attenuates TLR4-mediated NF-κB signaling in B cells

“…In the present study, IC/Ig was demonstrated to suppress TLR4-triggered IL-6 secretion, but not TNF-α production, in B cells. A previous study has reported that LPS-triggered IL-6 release from RAW264.7 macrophages is inhibited by 16α, 17α-epoxypregnenolone-20-oxime (EPREGO), but EPREGO does not affect TNF-α secretion (20). Therefore, it is possible that LPS may induce activation of different signaling pathways for different cytokine secretion and the signaling pathways responsible for IL-6 secretion, but for TNF-α secretion, are inhibited by IC.…”

Oximes: Novel Therapeutics with Anticancer and Anti-Inflammatory Potential

“…16α,17β-Epoxypregnenolone-20-oxime was reported to inhibit LPS-induced JNK phosphorylation, iNOS expression, and NO production in BV-2 microglial cells and RAW264.7 macrophages [ 164 , 165 ]. Likewise, the introduction of an oxime at position 12 of dehydroabietic acid, an aromatic abietane-type diterpenoid, increased its anti-proliferative and anti-inflammatory activities in pancreatic cancer Aspc-1 cells [ 166 ].…”