Yun Xu

Hydroxy-safflor yellow A attenuates Aβ1-42-induced inflammation by modulating the JAK2/STAT3/NF-κB pathway

Beta-amyloid (Aβ)-mediated inflammation plays a critical role in the initiation and progression of Alzheimer׳s disease (AD). Anti-inflammatory treatment may provide therapeutic benefits. In this study, the effect of hydroxy-safflor yellow A (HSYA) on Aβ1-42-induced inflammation in AD mice was investigated and the underlying mechanisms were explored. Aβ1-42 was injected into bilateral hippocampi of mice to induce AD models in vivo. Spatial learning and memory of mice were investigated by the Morris water maze test. Activated microglia and astrocytes were examined by immunofluorescence staining for ionized calcium-binding adapter molecule-1 (Iba-1) and glial fibrillary acidic protein (GFAP). The mRNA of inflammatory cytokines were measured using real-time PCR. NF-κB p65 translocation was analyzed by western blotting and immunostaining. IκB and phosphorylation of JAK2 and STAT3 were tested by western blotting. The results showed that HSYA ameliorated the memory deficits in Aβ1-42-induced AD mice. HSYA suppressed Aβ1-42-induced activation of microglia and astrocytes and reduced the mRNA expression of pro-inflammatory mediators. HSYA up-regulated the JAK2/STAT3 pathway and inhibits the activation of NF-κB signaling pathways. Pharmacological inhibition of STAT3 by AG490 reversed the inactivation of p65 and anti-inflammatory effects of HSYA. In conclusion, these results suggest that HSYA protects Aβ1-42-induced AD model through inhibiting inflammatory response, which may involve the JAK2/STAT3/NF-κB pathway.

Dalesconols B inhibits lipopolysaccharide induced inflammation and suppresses NF-κB and p38/JNK activation in microglial cells

Therapeutic strategies designed to inhibit the activation of microglia may lead to significant advancement in the treatment of most neurodegenerative diseases. Dalesconols B, also termed as TL2, is a newly found polyketide from a mantis-associated fungus and has been reported to exert potent immunosuppressive effects. In the present study, the anti-inflammatory effects of TL2 was investigated in lipopolysaccharide (LPS)-treated BV2 microglia and primary microglia cells. Our observations indicated that pretreatment with TL2 significantly inhibited the production of NO and PGE2 and suppressed the expression of pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS), COX-2, TNF-α, IL-1β, IL-6, MCP-1 and MIP-1α in LPS-stimulated BV2 microglia. The nuclear translocation of NF-κB and the phosphorylation level of Akt, p38 and JNK MAP kinase pathways were also inhibited by TL2 in LPS-treated BV2 microglia. Moreover, TL2 also decreased Aβ-induced production of TNF-α, IL-1β and IL-6 in BV2 microglia. Additionally, TL2 protected primary cortical neurons against microglia-mediated neurotoxicity. Overall, our findings suggested that TL2 might be a promising therapeutic agent for alleviating the progress of neurodegenerative diseases associated with microglia activation.

Human umbilical cord mesenchymal stem cells protect against ischemic brain injury in mouse by regulating peripheral immunoinflammation

Current treatments for ischemic stroke are limited, stem cell transplantation offers great potential as a therapeutic strategy. The present study was undertaken to determine whether human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) could improve brain injury after middle cerebral artery occlusion (MCAO) through modulating peripheral immunoinflammation. The study showed that neurological deficit was ameliorated and brain edema, infarct volume was significantly decreased from 72 h to 1 week post-MCAO with hUC-MSCs treatment via tail vein injection within 30 mins after stroke; hUC-MSCs attenuated the levels of inflammatory factors including IL-1, TNF-α, IL-23, IL-17 and IL-10 in peripheral blood serum and ischemia hemisphere after stroke; hUC-MSCs significantly decreased the level of Th17 cells at 24h and increased the level of Tregs at 72 h post-MCAO in peripheral immune system; the level of TGF-β in blood serum was enhanced by hUC-MSCs. In conclusion, our findings suggested that hUC-MSCs had neuroprotection in MCAO mice by TGF-β modulating peripheral immune and hUC-MSCs may be as a potential therapy for ischemic stroke.

TL-2 attenuates β-amyloid induced neuronal apoptosis through the AKT/GSK-3β/β-catenin pathway.

β-amyloid (Aβ)-mediated neuronal apoptosis contributes to the progression of Alzheimers disease (AD), although the exact mechanism remains unclear. This study aimed to investigate whether Dalesconol B (TL-2), a potent immunosuppressive agent with an unusual carbon skeleton, could inhibit Aβ-induced apoptosis in vitro and in vivo and to explore the underlying mechanisms. Aβ(1-42) was injected to bilateral hippocampus of mice to make the AD models in vivo. TL-2 was able to cross the blood-brain barrier and attenuate memory deficits in the AD mice. TL-2 also inhibited Aβ(1-42)-induced neuronal apoptosis in vitro and in vivo. In addition, TL-2 could activate the AKT/GSK-3β pathway, and inhibition of AKT and activation of GSK-3β partially eliminated the neuroprotective effects of TL-2. Furthermore, TL-2 induced the nuclear translocation of β-catenin and enhanced its transcriptional activity through the AKT/GSK-3β pathway to promote neuronal survival. These results suggest that TL-2 might be a potential drug for AD treatment.

Malibatol A protects against brain injury through reversing mitochondrial dysfunction in experimental stroke

Ischemic stroke is particularly susceptible to free radicals mediated secondary neuronal damage, especially mitochondrial dysfunction. Malibatol A (MA), a novel resveratrol oligomer, has shown potential antioxidant property in vitro. But little is known about its effect on central nervous system (CNS) in vivo. In the present study, the effect of MA was evaluated in focal cerebral ischemia induced by right middle cerebral artery occlusion (MCAO) in mice. MA at the dose of 20u2009mg/kg was administered by caudal-vein injection within 15u2009min after reperfusion. At 24u2009h after cerebral ischemia/reperfusion (I/R) injury, ameliorated neurological scores and reduced infarct volume was observed in MA treated group. Also, MA treatment restored the increased levels of reactive oxygen species (ROS), 3-Nitrotyrosine (3-NT), and 4-Hydroxynonenal (4-HNE) induced by MCAO. The activities of respiratory enzyme complex I, III and mitochondrial transmembrane potential (Δm) were effectively preserved compared with MCAO group through MA treatment. Western blot analysis showed a marked increase in Bcl-2 and decrease in Bax expression after MA treatment as compared with MCAO group. Moreover, MA treatment prevented release of cytochrome c from mitochondria into cytoplasm and blunted activities of caspase-9 and caspase-3. Collectively, the present study indicates that MA can ameliorate MCAO-induced mitochondrial dysfunction, and this might partially contribute to its protective effect on brain damage after 24u2009h of I/R injury.

Hydroxy-safflor yellow A inhibits neuroinflammation mediated by Aβ1-42 in BV-2 cells

Inflammation is an important contributor to the development of Alzheimers disease (AD). Anti-inflammatory medication may offer promising treatment for AD. Hydroxy-safflor yellow A (HSYA), a chemical component of the safflower yellow pigments, has been reported to exert potent immunosuppressive effects. This study examined the anti-inflammatory effects of HSYA in Aβ₁₋₄₂-treated BV-2 microglia cells. The mRNA levels of IL-1β, IL-4, IL-10, TNF-α, COX-2 and iNOS were detected by real-time PCR. Western blotting was used to determine the protein expression of COX-2, TNF-α, iNOS, Janus Kinase 2 (JAK2), p-JAK2, signal transducers and activators of transcription 3 (STAT3) and p-STAT3. BV2-conditioned medium was used to treat SH-SY5Y cells and primary neuronal cells in indirect toxicity experiments. Cell viability and apoptosis were assessed using MTT assay and Annexin V/PI staining respectively. The results demonstrated that HSYA significantly reduced the expression of the pro-inflammatory mediators and inhibited Aβ₁₋₄₂-induced neuroinflammation. Moreover, HSYA protected primary cortical neurons and SH-SY5Y cells against microglia-mediated neurotoxicity. HSYA also enhanced the phosphorylation of JAK2/STAT3 pathway and inhibition of JAK2 by AG 490 attenuated the anti-inflammatory effects of HSYA. Overall, our findings suggested that HSYA inhibited Aβ₁₋₄₂-induced inflammation and conferred neuroprotection partially through JAK2/STAT3 pathway, indicating that HSYA could be a potential drug for the treatment of AD.

Ampelopsin attenuates lipopolysaccharide-induced inflammatory response through the inhibition of the NF-κB and JAK2/STAT3 signaling pathways in microglia.

&NA; Increasing evidence suggests that microglia are a major cellular contributor to neuroinflammation. The present study investigated whether Ampelopsin (Amp), a type of flavanonol derivative from Ampelopsis grossedentata, may exert an anti‐inflammatory effect on lipopolysaccharide (LPS)‐induced BV2 and primary microglia cells. We found that pre‐treatment of microglia cells with Amp before LPS with a non‐cytotoxic concentration range decreased the production of nitric oxide (NO) and prostaglandin E2 (PGE2). Amp also suppressed the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase‐2 (COX‐2) at the mRNA and protein levels. In addition, LPS‐induced production of pro‐inflammatory cytokines such as interleukin (IL)‐1&bgr;, IL‐6, and tumor necrosis factor‐&agr; (TNF‐&agr;) was obviously reduced by Amp. Our mechanistic study indicated that Amp suppressed LPS‐induced activation of the I&kgr;B/NF‐&kgr;B inflammation pathway without affecting changes in the phosphorylation levels of mitogen‐activated protein kinases (MAPKs) in BV2 cells. Further studies revealed that Amp markedly reduced the phosphorylation levels of JAK2‐STAT3 and STAT3 nuclear translocation. Overall, our data suggest that Amp can suppress the LPS‐induced inflammatory response of microglial cells, indicating that Amp has potential for the treatment of inflammation‐mediated neurodegenerative diseases. HighlightsAmpelopsin (Amp) reduces NO and PGE2 production in LPS‐induced microglia.Amp inhibits iNOS and COX‐2 expression in LPS‐induced microglia.Amp inhibits the production of IL‐1&bgr;, IL‐6 and TNF‐&agr; in LPS‐induced microglia.Amp inhibits inflammation by suppressing NF‐&kgr;B and JAK2/STAT3 signaling pathways.

Hyperbaric Oxygen Suppresses Hypoxic-Ischemic Brain Damage in Newborn Rats

The optimal therapeutic time-window and protective mechanism of hyperbaric oxygen in hypoxic-ischemic brain damage remain unclear. This study aimed to determine the neuroprotective effects of hyperbaric oxygen. Following hypoxic-ischemic brain damage modeling in neonatal rats, hyperbaric oxygen was administered at 6, 24, 48, and 72 hours and 1 week after hypoxia, respectively, once daily for 1 week. Fourteen days after hypoxic-ischemic brain damage, cell density and apoptosis rate, number of Fas-L+, caspase-8+, and caspase-3+ neuronal cells, levels of nitric oxide, malondialdehyde, and superoxide dismutase in hippocampus were examined. Morris water maze test was conducted 28 days after insult. Significant improvements were found in cell density, rate of apoptosis, oxidative stress markers, FasL, and caspases in rats treated with hyperbaric oxygen within 72 hours compared to hypoxic-ischemic injury. Similarly, time-dependent behavioral amelioration was observed in pups treated with hyperbaric oxygen. Our findings suggest that hyperbaric oxygen protects against hypoxic-ischemic brain damage by inhibiting oxidative stress and FasL-induced apoptosis, and optimal therapeutic time window is within 72 hours after hypoxic-ischemic brain damage.

Esculentoside A exerts anti-inflammatory activity in microglial cells

Abstract Esculentoside A (EsA) is a saponin isolated from the roots of Phytolacca esculenta. This study was designed to evaluate the pharmacological effects of EsA on lipopolysaccharide (LPS)‐stimulated BV2 microglia and primary microglia cells. Our results indicated that EsA pretreatment significantly decreased LPS‐induced production of Nitric Oxide (NO) and Prostaglandin E2 (PGE2) and impeded LPS‐mediated upregulation of pro‐inflammatory mediators’ expression such as nitric oxide synthase (iNOS), cyclooxygenase‐2 (COX‐2), interleukin‐1&bgr; (IL‐1&bgr;), interleukin‐6 (IL‐6), interleukin‐12 (IL‐12) and tumor necrosis factor‐a (TNF‐&agr;) in both BV2 microglia and primary microglia cells. Moreover, EsA markedly suppressed nuclear factor‐&kgr;B p65 (NF‐&kgr;B p65) translocation by blocking I&kgr;B‐&agr; phosphorylation and degradation in LPS‐treated BV2 cells. EsA also decreased phosphorylation level of mitogen‐activated protein kinases (MAPKs) and inhibited NOD‐like receptor pyrin domain‐containing protein 3 (NLRP3) inflammasome mediated caspase‐1 activation in LPS‐stimulated BV2 cells. Additionally, EsA decreased &bgr;‐amyloid1–42 (A&bgr;1–42)‐induced production of TNF‐&agr;, IL‐1&bgr; and IL‐6 in primary microglia. Thus, EsA might be a promising therapeutic agent for alleviating neuroinflammatory diseases. HighlightsEsA attenuated LPS‐induced inflammatory mediators’ production in activated microglia.The anti‐inflammatory effects of EsA was associated with the inactivation of NF‐&kgr;B, MAPKs and NLRP3 pathways.EsA suppressed mRNA levels of cytokines in A&bgr;1–42‐induced primary microglia cells.

Malibatol A enhances alternative activation of microglia by inhibiting phosphorylation of Mammalian Ste20-like kinase1 in OGD-BV-2 cells

Objective: To investigate the polarization effect of Malibatol A on oxygen-glucose deprivation (OGD)-BV-2 cells, and the possible molecular mechanism involved in c-Abl-MST signaling pathway. Method: The OGD BV-2 cell model was established. BV-2 cells were exposed to OGD for 8 h followed by reperfusion for 15 h with Malibatol A at different concentration of 0.5, 1, 2, 4, 8, 16 μM or without it. And then cells, mRNA and protein were harvested respectively. The cell viability and apoptosis were measured by MTT assay and flow cytometry. The mRNA of classical activated microglia (M1) markers (MCP-1, IL-1 and TNF-α) and alternatively activated microglia (M2) markers (Ym-1, CD206, IL-10, TGF-β) in BV-2 cells were measured by RT-PCR. Meanwhile, the proteins of Ym-1 and CD206 was assayed by flow cytometry. Furthermore, the expression of c-Abl and MST was measured by Western blot. Result: Malibatol A significantly decreased apoptosis and increased viability of OGD BV-2 cells in a dose-dependent manner. In the presence of Malibatol A, the mRNA levels of Ym-1, CD206, IL-10 and TGF-β mRNA was significantly increased in OGD-BV-2 cells, while the mRNA levels of MCP-1, IL-1 and TNF-α was obviously down-regulated. Meanwhile, the proteins of Ym-1 and CD206 was raised in OGD BV-2 cells with Malibatol A. Besides, Malibatol A also inhibited OGD-induced p-MST1(Y433) in BV-2 cells. Conclusion: Malibatol A could attenuate OGD-induced BV-2 cell injury and promote M2 microglia polarization. The mechanism may be related to inhibition of MST1 phosphorylation at Y433.