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Aims This study explored sFasL expression in neurons and the potential role of neuronal sFasL in modulating the microglial phenotypes. Methods In vivo, middle cerebral artery occlusion ( MCAO) was induced in both FasL-mutant ( gld) and wild-type (wt) mice. In vitro, primary cortical neuron or microglia or coculture from wt/ gld mice was subjected to oxygen glucose deprivation ( OGD). sFasL level in the supernatant was evaluated by ELISA. Neuronal-conditioned medium (NCM) or exogenous sFasL was applied to primary microglia with or without FasL neutralizing antibody. Protein expression of JAK2/ STAT3 and NF-κB pathways were determined by Western blot. The effect of microglia phenotype from wt/ gld mice on the fate of ischemic neurons was further elucidated. Results In vivo, compared with wild-type mice, M1 markers ( CD16, CD32 and iNOS) were attenuated in gld mice after MCAO. In vitro, post- OGD neuron released more sFasL. Both post- OGD NCM and exogenous sFasL could trigger M1-microglial polarization. However, this M1 phenotype shift was partially blocked by utilization of FasL neutralizing antibody or gld NCM. Consistently, JAK2/ STAT3 and NF-κB signal pathways were both activated in microglia after exogenous sFasL treatment. Compared with wild-type mice, M1-conditioned medium prepared from gld mice protected neuron against OGD injury. Conclusions Ischemic neurons release sFasL, which contributes to M1-microglial polarization. The underlying mechanisms may involve the activation of JAK2/ STAT3 and NF-κB signaling pathways. [ABSTRACT FROM AUTHOR]

Abstract Fine particulate matter (PM 2.5) exposure could cause many acute and chronic respiratory diseases. In this study the protective effects of polysaccharide from Morchella esculenta (FMP-1) and its derivatives against PM 2.5 -induced inflammation were evaluated. By flow cytometry and ELISA analysis, sulfated polysaccharide SFMP-1 showed the best protective effect in reducing PM 2.5 -induced cell death, cell apoptosis and production of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), which was accompanied by a diminished level in reactive oxygen species (ROS) formation caused by PM 2.5 in rat alveolar macrophage NR8383 cells. Furthermore, the mechanism was studied by immunofluorescence, qRT-PCR and western blotting. SFMP-1 could down-regulate the expression of inducible NO synthesis (iNOS) and cyclooxygenase-2 (COX-2) at both mRNA and protein levels in PM 2.5 -treated cells. The PM 2.5 -induced phosphorylation of nuclear factor-kappa B (NF-κB) was also reduced through suppressing nuclear translation of the NF-κB and inhibiting the degradation and phosphorylation of IκBα. These results indicated that SFMP-1 could protect NR8383 cells from PM 2.5 -induced inflammation by inhibiting NF-κB activation. Highlights • Polysaccharide from Morchella esculenta (FMP-1) was chemically modified to obtain sulfated and carboxymethylated derivatives. • Protection of FMP-1 and its derivatives against PM 2.5 -induced inflammation were comparatively investigated. • Sulfated polysaccharide SFMP-1 showed the best protective effect in PM 2.5 -treated alveolar macrophage NR8383 cells. • SFMP-1 could protect NR8383 cells from PM 2.5 -induced inflammation by inhibiting NF-κB activation. [ABSTRACT FROM AUTHOR]

Sepsis, a hyperinflammatory response that can result in multiple organ dysfunctions, is a leading cause of mortality from infection. Here, we show that orphan nuclear receptor Nur77 (also known as TR3) can enhance resistance to lipopolysaccharide (LPS)-induced sepsis in mice by inhibiting NF-κB activity and suppressing aberrant cytokine production. Nur77 directly associates with p65 to block its binding to the κB element. However, this function of Nur77 is countered by the LPS-activated p38α phosphorylation of Nur77. Dampening the interaction between Nur77 and p38α would favor Nur77 suppression of the hyperinflammatory response. A compound, n-pentyl 2-[3,5-dihydroxy-2-(1-nonanoyl) phenyl]acetate, screened from a Nur77-biased library, blocked the Nur77-p38α interaction by targeting the ligand-binding domain of Nur77 and restored the suppression of the hyperinflammatory response through Nur77 inhibition of NF-κB. This study associates the nuclear receptor with immune homeostasis and implicates a new therapeutic strategy to treat hyperinflammatory responses by targeting a p38α substrate to modulate p38α-regulated functions. [ABSTRACT FROM AUTHOR]

Toll-like receptors 2 and 4 (TLR2/4) and the downstream nuclear factor-kappa B (NF-κB) signaling pathway, which mediate the inflammatory reaction in cerebral ischemia, were demonstrated to be involved in the extension of cerebral infarction and the aggravation of ischemic brain damage. Reports showed that curcumin provides neuroprotection against ischemic brain damage. In this study, we investigated whether curcumin inhibits the activation of TLR2/4-NF-κB signaling pathway in rats of permanent focal cerebral ischemia. Adult male Sprague-Dawley rats underwent permanent middle cerebral artery occlusion (pMCAO). Curcumin was administered by intraperitoneal injection twice at 2 and 12 h after the onset of ischemia. Neurological deficit scores, cerebral infarct size, morphological characteristic, and cerebral water content were measured after 24 h of pMCAO. The enzymatic activity of myeloperoxidase (MPO) was assessed after 24 h of pMCAO. Expression of TLR2 and TLR4 in ischemic brain was determined by western blot. Expression of NF-κB p65 in ischemic brain was detected by immunohistochemistry and western blot. The release of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in blood was examined by ELISA. Curcumin significantly reduced neurological deficit scores, cerebral infarct size, neuronal damage, cerebral water content, and MPO activity. It also inhibited the expression of TLR2/4 and decreased the expression and activity of NF-κB p65 in rat brain. In addition, curcumin attenuated the release of TNF-α and IL-1β in blood. Our results suggest that curcumin reduces inflammatory reaction and brain damage in a rat model of permanent focal cerebral ischemia. The neuroprotective effect and anti-inflammatory property of curcumin in cerebral ischemia might be associated with the inhibition of TLR2/4-NF-κB signaling pathway. [ABSTRACT FROM AUTHOR]

The TGF-β (transforming growth factor-β) pathway represents an important signalling pathway involved in regulating diverse biological processes, including cell proliferation, differentiation and inflammation. Despite the critical role for TGF-β in inflammatory responses, its role in regulating NF-κB (nuclear factor-κB)-dependent inflammatory responses still remains unknown. In the present study we show that TGF-β1 synergizes with proinflammatory cytokine TNF-α (tumour necrosis factor-α) to induce NF-κB activation and the resultant inflammatory response in vitro and in vivo. TGF-β1 synergistically enhances TNF-α-induced NF-κB DNA binding activity via induction of RelA acetylation. Moreover, synergistic enhancement of TNF-α-induced RelA acetylation and DNA-binding activity by TGF-β1 is mediated by PKA (protein kinase A). Thus the present study reveals a novel role for TGF-β in inflammatory responses and provides new insight into the regulation of NF-κB by TGF-β signalling. [ABSTRACT FROM AUTHOR]

• Chronic cold stress activated microglia in the hippocampus of mice. • GABA mediated the activation of microglia. • The NLRP3 inflammasome and NF-κB pathways involved the activation of microglia. Chronic cold stress has long-term dramatic effects on the animal immune and neuroendocrine systems. As one of the important regions of the brain, the hippocampus is the main region involved in response to stressors. Nevertheless, the impact to the hippocampus following cold exposure and the underlying mechanism involved are not clear. To evaluate the response of the hippocampus during chronic cold stress, male C57BL/6 mice were exposed to 4 °C, 3 h per day for 1 week, after which neuroinflammation and the molecular and signaling pathways in the hippocampus response to cold stress were investigated. To confirm the potential mechanism, BV2 cells were treated with γ-aminobutyric acid (GABA) and BAY 11-7082 and MCC950, then the activation of microglia and key proteins involved in the regulation of inflammation were measured. We demonstrated that chronic cold stress induced the activation of microglia, the emergence of neuroinflammation, and the impairment of neurons in the hippocampus, which might be the result of GABA-mediated activation of nod-like receptor protein 3 (NLRP3) inflammasome and the nuclear factor kappa B (NF-κB) signaling pathway. [ABSTRACT FROM AUTHOR]