Piperine inhibits lipopolysaccharide-induced maturation of bone-marrow-derived dendritic cells through inhibition of ERK and JNK activation.

Piperine, one of the main components of Piper longum Linn. and P. nigrum Linn., is a plant alkaloid with a long history of medicinal use. Piperine has been shown to modulate the immune response, but the mechanism underlying this modulation remains unknown. Here, we examined the effects of piperine on lipopolysaccharide (LPS)-induced inflammatory responses in bone-marrow-derived dendritic cells (BMDCs). Piperine significantly inhibited the expression of major histocompatibility complex class II, CD40 and CD86 in BMDCs in a dose-dependent manner. Furthermore, piperine treatment led to an increase in fluorescein-isothiocyanate-dextran uptake in LPS-treated dendritic cells and inhibited the production of tumour necrosis factor alpha and interleukin (IL)-12, but not IL-6. The inhibitory effects of piperine were mediated via suppression of extracellular signal-regulated kinases and c-Jun N-terminal kinases activation, but not p38 or nuclear factor-κB activation. These findings provide insight into the immunopharmacological role of piperine.

Myrrh inhibits LPS-induced inflammatory response and protects from cecal ligation and puncture-induced sepsis.

Myrrh has been used as an antibacterial and anti-inflammatory agent. However, effect of myrrh on peritoneal macrophages and clinically relevant models of septic shock, such as cecal ligation and puncture (CLP), is not well understood. Here, we investigated the inhibitory effect and mechanism(s) of myrrh on inflammatory responses. Myrrh inhibited LPS-induced productions of inflammatory mediators such as nitric oxide, prostaglandin E(2), and tumor necrosis factor-α but not of interleukin (IL)-1ß and IL-6 in peritoneal macrophages. In addition, Myrrh inhibited LPS-induced activation of c-jun NH(2)-terminal kinase (JNK) but not of extracellular signal-regulated kinase (ERK), p38, and nuclear factor-κB. Administration of Myrrh reduced the CLP-induced mortality and bacterial counts and inhibited inflammatory mediators. Furthermore, administration of Myrrh attenuated CLP-induced liver damages, which were mainly evidenced by decreased infiltration of leukocytes and aspartate aminotransferase/alanine aminotransferase level. Taken together, these results provide the evidence for the anti-inflammatory and antibacterial potential of Myrrh in sepsis.

2',4',6'-Tris(methoxymethoxy) chalcone (TMMC) attenuates the severity of cerulein-induced acute pancreatitis and associated lung injury.

Acute pancreatitis (AP) is an inflammatory disease involving acinar cell injury and rapid production and release of inflammatory cytokines, which play a dominant role in local pancreatic inflammation and systemic complications. 2',4',6'-Tris (methoxymethoxy) chalcone (TMMC), a synthetic chalcone derivative, displays potent anti-inflammatory effects. Therefore, we aimed to investigate whether TMMC might affect the severity of AP and pancreatitis-associated lung injury in mice. We used the cerulein hyperstimulation model of AP. Severity of pancreatitis was determined in cerulein-injected mice by histological analysis and neutrophil sequestration. The pretreatment of mice with TMMC reduced the severity of AP and pancreatitis-associated lung injury and inhibited several biochemical parameters (activity of amylase, lipase, trypsin, trypsinogen, and myeloperoxidase and production of proinflammatory cytokines). In addition, TMMC inhibited pancreatic acinar cell death and production of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 by inhibiting NF-κB and extracellular signal-regulated protein kinase 1/2 (ERK1/2) activation. Neutralizing antibodies for TNF-α, IL-1ß, and IL-6 inhibited cerulein-induced cell death in isolated pancreatic acinar cells. Moreover, pharmacological blockade of NF-κB/ERK1/2 reduced acinar cell death and production of TNF-α, IL-1ß, and IL-6 in isolated pancreatic acinar cells. In addition, posttreatment of mice with TMMC showed reduced severity of AP and lung injury. Our results suggest that TMMC may reduce the complications associated with pancreatitis.

Piperine ameliorates the severity of cerulein-induced acute pancreatitis by inhibiting the activation of mitogen activated protein kinases.

Piperine is a phenolic component of black pepper (Piper nigrum) and long pepper (Piper longum), fruits used in traditional Asian medicine. Our previous study showed that piperine inhibits lipopolysaccharide-induced inflammatory responses. In this study, we investigated whether piperine reduces the severity of cerulein-induced acute pancreatitis (AP). Administration of piperine reduced histologic damage and myeloperoxidase (MPO) activity in the pancreas and ameliorated many of the examined laboratory parameters, including the pancreatic weight (PW) to body weight (BW) ratio, as well as serum levels of amylase and lipase and trypsin activity. Furthermore, piperine pretreatment reduced the production of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 during cerulein-induced AP. In accordance with in vivo results, piperine reduced cell death, amylase and lipase activity, and cytokine production in isolated cerulein-treated pancreatic acinar cells. In addition, piperine inhibited the activation of mitogen-activated protein kinases (MAPKs). These findings suggest that the anti-inflammatory effect of piperine in cerulein-induced AP is mediated by inhibiting the activation of MAPKs. Thus, piperine may have a protective effect against AP.

The roots of Nardostachys jatamansi inhibits lipopolysaccharide-induced endotoxin shock.

Nardostachys jatamansi (NJ) has been used in the treatment of inflammatory diseases. However, it is not clear how NJ produces anti-inflammatory effects. In the present study, using an experimental model of lipopolysaccharide (LPS)-induced endotoxin shock, the protective effects and mechanisms of action of NJ were investigated. The water extract of roots of NJ was administrated to mice orally (1, 5, and 10 mg/kg) 1 h after or before LPS challenge. The administration of NJ inhibited LPS-induced endotoxin shock and the production of inflammatory mediators, such as interleukin (IL)-1ß, IL-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-α/ß. Murine peritoneal macrophages were used to determine the production of inflammatory mediators. In peritoneal macrophages, NJ also inhibited LPS-induced production of inflammatory mediators, such as IL-1ß, IL-6, TNF-α, and IFN-α/ß. In addition, NJ reduced the activation of mitogen-activated protein kinases (MAPKs) and the level of expression of interferon regulatory factor (IRF)-1 and IRF-7 mRNA. Furthermore, post-treatment with NJ reduced LPS-induced endotoxin shock and the production of inflammatory mediators. These results suggest that NJ inhibits endotoxin shock by inhibiting the production of IL-1ß, IL-6, TNF-α, and IFN-α/ß through the inhibition of MAPKs activation and IRF induction.

Tranilast, an orally active anti-allergic drug, up-regulates the anti-inflammatory heme oxygenase-1 expression but down-regulates the pro-inflammatory cyclooxygenase-2 and inducible nitric oxide synthase expression in RAW264.7 macrophages.

Tranilast (N-[3',4'-dimethoxycinnamonyl] anthranilic acid), an orally active anti-allergic drug, is reported to exert the anti-inflammatory effects, but the underlying mechanisms that could explain the anti-inflammatory actions of tranilast remain largely unknown. Here, we found that tranilast induces heme oxygenase-1 (HO-1) expression through the extracellular signal-regulated kinase-1/2 (ERK1/2) pathway in RAW264.7 macrophages. Tranilast suppressed cyclooxygenase-2 (COX-2) and inducible nitric oxide (NO) synthase (iNOS) expression, and thereby reduced COX-2-derived prostaglandin E(2) (PGE(2)) and iNOS-derived NO production in lipopolysaccharide (LPS)-stimulated macrophages. Similarly, tranilast diminished tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) production. Interestingly, the effects of tranilast on LPS-induced PGE(2), NO, TNF-alpha, and IL-1beta production were partially reversed by the HO-1 inhibitor tin protoporphyrin, suggesting that tranilast-induced HO-1 expression is at least partly responsible for the resulting anti-inflammatory effects of the drug. Thus, HO-1 expression via ERK1/2 activation may be at least one of the possible mechanisms explaining the anti-inflammatory actions of tranilast.