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Brain damage or exposure to inflammatory agents provokes the activation of microglia and secretion of pro-inflammatory and neurotoxic mediators responsible for neuronal loss. Several lines of evidence show that resveratrol, a natural non-flavonoid polyphenol, may exert a neuroprotective action in neurodegenerative diseases. Suppressor of cytokine signaling (SOCS) proteins are a family of eight members expressed by immune cells and the central nervous system (CNS) cells, that regulate immune processes within the CNS, including microglia activation. We demonstrate that resveratrol had anti-inflammatory effects in murine N13 microglial cells stimulated with lipopolysaccharide (LPS), through up-regulating SOCS-1 expression. Interestingly, in SOCS-1-silenced cells resveratrol failed to play a protective role after LPS treatment. Our data demonstrate that resveratrol can impair microglia activation by activating a SOCS-1 mediated signaling pathway.

Farmed fish are exposed to a continuous antigenic pressure by microbial and environmental agents, which may lead to a condition of chronic inflammation. In view of the notion that polyphenols, largely contained in fruits and vegetables, are endowed with antioxidant and anti-inflammatory activities, farmed sea bass (Dicentrarchus labraxL.) have been administered with red grape polyphenol-enriched feed. Polyphenols were extracted from the seeds ofCanosinaNero di TroiaVitis viniferaand mixed with conventional feed at two different concentrations (100 and 200 mg/kg, resp.). Fish samples collected at days 223 and 273, respectively, were evaluated for intestinal and spleen cytokine release as well as for spleen macrophage (MØ) and melanomacrophage center (MMC) areas and distribution. Data will show that in treated fish decrease of intestinal interleukin- (IL-) 1βand IL-6 and increase of splenic interferon- (IFN-)γoccur. On the other hand, in the spleen reduction of MØ number seems to parallel increase in MMCs. Collectively, these data suggest that polyphenol-administered sea bass generate lower levels of intestinal proinflammatory cytokines, while producing larger amounts of spleen IFN-γ, as an expression of a robust and protective adaptive immune response. Increase of MMCs corroborates the evidence for a protective spleen response induced by feed enriched with polyphenols.

The development of agents that can modulate microglial activation has been suggested as one potential strategy for the treatment or prevention of neurodegenerative diseases. Among these agents, resveratrol, with its anti-inflammatory action, has been described to have neuroprotective effects. In this paper we demonstrate that in LPS-stimulated microglia resveratrol pretreatment reduced, in a dose-dependent manner, pro-inflammatory cytokines IL-1β, TNF-α and IL-6 mRNA expression and increased the release of anti-inflammatory interleukin (IL)-10. Moreover, resveratrol pretreatment up-regulated the phosphorylated forms of JAK1 and STAT3, as well as suppressor of cytokine signaling (SOCS)3 protein expression in LPS activated cells, demonstrating that the JAK-STAT signaling pathway is involved in the anti-inflammatory effect exerted by resveratrol. By supplementing the cultures with an IL-10 neutralizing antibody (IL-10NA) we obtained the opposite effect. Taken together, these data allow us to conclude that the LPS-induced pro-inflammatory response in microglial cells can be markedly reduced by resveratrol, through IL-10 dependent up-regulation of SOCS3, requiring the JAK-STAT signaling pathway.

In the present study we used a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mouse model to analyze resveratrol neuroprotective effects. The MPTP-induced PD model is characterized by chronic inflammation, oxidative stress and loss of the dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). We observed that resveratrol treatment significantly reduced glial activation, decreasing the levels of IL-1β, IL-6 and TNF-α, as well as their respective receptors in the SNpc of MPTP-treated mice, as demonstrated by Western blotting, RT-PCR and quantitative PCR analysis. This reduction is related to possible neuroprotection as we also observed that resveratrol administration limited the decline of tyrosine hydroxylase-immunoreactivity induced in the striatum and SNpc by MPTP injection. Consistent with these data, resveratrol treatment up-regulated the expression of the suppressor of cytokine signaling-1 (SOCS-1), supporting the hypothesis that resveratrol protects DA neurons of the SNpc against MPTP-induced cell loss by regulating inflammatory reactions, possibly through SOCS-1 induction.

Upregulation of inflammatory responses in the brain is associated with a number of neurodegenerative diseases. Microglia are activated in neurodegenerative diseases, producing pro-inflammatory mediators. Critically, lipopolysaccharide (LPS)-induced microglial activation causes dopaminergic neurodegeneration in vitro and in vivo. The signaling mechanisms triggered by LPS to stimulate the release of pro-inflammatory mediators in microglial cells are still incompletely understood. To further explore the mechanisms of LPS-mediated inflammatory response of microglial cells, we studied the role of phosphatidylinositol 3-kinase (PI3K)/Akt signal transduction pathways known to be activated by toll-like receptor-4 signaling through LPS. In the current study, we report that the activation profile of LPS-induced pAkt activation preceded those of LPS-induced NF-κB activation, suggesting a role for PI3K/Akt in the pathway activation of NF-κB-dependent inflammatory responses of activated microglia. These results, providing the first evidence that PI3K dependent signaling is involved in the inflammatory responses of microglial cells following LPS stimulation, may be useful in preventing inflammatory based neurodegenerative processes.

Resveratrol is a natural phytoalexin present in a variety of plant species, such as grapes and red wine, that is well known for its anti-inflammatory effects. In addition, a cancer chemotherapeutic activity of resveratrol has been described. Here we evaluated the effect of resveratrol on COX-2 and prostaglandin E(2) production in human intestinal cells Caco-2 cells treated with lipopolysaccharide (LPS). Resveratrol concentration-dependently inhibited the expression of COX-2 mRNA in the LPS-treated cells, as well as protein expression, resulting in a decreased production of PGE(2). In order to investigate the mechanisms through which resveratrol exhibited these anti-inflammatory effects, we examined the activation of IκB in LPS-stimulated intestinal cells. Results demonstrated that resveratrol inhibited the translocation of NF-κB p65 subunits from the cytosol to the nucleus, which correlated with its inhibitory effects on IκBα phosphorylation and degradation. These results suggest that the down-regulation of COX-2 and PGE(2) by resveratrol may be related to NF-κB inhibition through the negative regulation of IKK phosphorylation in intestinal cells.

Giardia intestinalis is a protozoan that causes a generally self-limited clinical illness typically characterized by diarrhea, abdominal cramps, bloating, weight loss and malabsorption. The pathogenesis of giardiasis is multifactorial and probably different in various animal models, but the mechanisms responsible for the disease are still poorly understood. We previously reported that G. intestinalis is able to induce apoptosis in the human HCT-8 epithelial cell line through the activation of both the intrinsic and extrinsic apoptotic pathways. In the present study we demonstrate that activation of the mitogen-activated protein kinases (MAPKs) plays an important role in the regulation of HCT-8 cell apoptosis induced by G. intestinalis. MAPK activation seems to correlate with regulation of the apoptotic process because specific MAPK inhibitors significantly reduced the expression of the active form of caspase-3 in infected cells. Apoptotic changes were also dramatically inhibited by pre-treatment of the cells with JNK or p38 specific inhibitors, but not ERK 1/2 inhibitor. Taken together, these results suggest a critical role for MAPK activation in G. intestinalis-induced apoptosis in the human HCT-8 cell line.