Yu-Hsiang Kuan

Rutin decreases lipopolysaccharide-induced acute lung injury via inhibition of oxidative stress and the MAPK-NF-κB pathway.

Acute lung injury (ALI) is a serious disease with unacceptably high mortality and morbidity rates. Up to now, no effective therapeutic strategy for ALI has been established. Rutin, quercetin-3-rhamnosyl glucoside, expresses a wide range of biological activities and pharmacological effects, such as anti-inflammatory, antihypertensive, anticarcinogenic, vasoprotective, and cardioprotective activities. Pretreatment with rutin inhibited not only histopathological changes in lung tissues but also infiltration of polymorphonuclear granulocytes into bronchoalveolar lavage fluid in lipopolysaccharide (LPS)-induced ALI. In addition, LPS-induced inflammatory responses, including increased secretion of proinflammatory cytokines and lipid peroxidation, were inhibited by rutin in a concentration-dependent manner. Furthermore, rutin suppressed phosphorylation of NF-κB and MAPK and degradation of IκB, an NF-κB inhibitor. Decreased activities of antioxidative enzymes such as superoxide dismutase, catalase, glutathione peroxidase, and heme oxygenase-1 caused by LPS were reversed by rutin. At the same time, we found that ALI amelioration by chelation of extracellular metal ions with rutin is more efficacious than with deferoxamine. These results indicate that the protective mechanism of rutin is through inhibition of MAPK-NF-κB activation and upregulation of antioxidative enzymes.

Tetramethylpyrazine reduces cellular inflammatory response following permanent focal cerebral ischemia in rats.

Tetramethylpyrazine (TMP) has been used to treat ischemic stroke. However, scientific evidence related to its effectiveness or precise modes of neuroprotective action is largely unclear. This study provides evidence of an alternative target for TMP and sheds light on the mechanism of its physiological benefits. We report a global inhibitory effect of TMP on intracerebral cellular inflammatory response in a rat model of permanent cerebral ischemia. TMP exhibited a neuroprotective effect against ischemic deficits by reduction of behavioral disturbance, brain infarction, and edema. The results of immunohistochemistry, enzymatic assay, Western blot, real-time reverse transcriptase-polymerase chain reaction (RT-PCR), and flow cytometric analysis revealed that TMP reduced the percentages of activated macrophages/microglia and infiltrative lymphocytes, neutrophils, and macrophages and pro-inflammatory cytokine expression after cerebral ischemia. In parallel with these immunosuppressive phenomena, TMP also attenuated the activities of ischemia-induced inflammation-associated signaling molecules and transcription factors. Another finding in this study was that the anti-inflammatory and neuroprotective effects of TMP were accompanied by a further elevated expression of NF-E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in ipsilateral neurons and macrophages/microglia after cerebral ischemia. Taken together, our results suggest that both the promotion of endogenous defense capacity and the attenuation of the extent and composition percentage of the major cellular inflammatory responses via targeting of macrophages/microglia by elevating Nrf2/HO-1 expression might actively contribute to TMP-mediated neuroprotection against cerebral ischemia.

Luteolin attenuates the pulmonary inflammatory response involves abilities of antioxidation and inhibition of MAPK and NFκB pathways in mice with endotoxin-induced acute lung injury.

Acute lung injury (ALI) in critically ill patients remains the leading cause of mortality and morbidity. Lipopolysaccharide (LPS) is a key mediator of lung injury. This study investigates the protective effects and mechanisms of luteolin in intratracheal instillation of LPS (100μg)-induced ALI in mice. Pretreatment of mice with 70μmol/kg luteolin significantly restores LPS-induced decrease in oxygen pressure and increase in carbon dioxide in arterial blood. The histopathological study established 70μmol/kg luteolin pretreatment markedly attenuates lung histopathological changes, such as haemorrhaging, interstitial edema, and infiltration of polymorphonuclear neutrophils (PMNs) into the lung parenchyma and alveolar spaces. Sufficient evidence for luteolin (35 and 70μmol/kg) suppresses activation and infiltration of PMNs is obtained in expression of surface marker CD11b and Ly6G on cells in bronchoalveolar lavage fluid (BALF) cells and myeloperoxidase activity in lung tissue. Furthermore, luteolin reduces the activity of catalase and superoxide dismutase, and the level of oxidative damage, and lipid peroxidation, in lung tissue. In addition, the secretion of TNF-α, KC, and ICAM-1 in the BALF after LPS challenge are also inhibited by luteolin. Moreover, luteolin reduced LPS-induced activation of MAPK and NFκB pathways. Therefore, luteolin is a potential protective antagonists for LPS-induced ALI in mice.

Protective effects of luteolin against lipopolysaccharide-induced acute lung injury involves inhibition of MEK/ERK and PI3K/Akt pathways in neutrophils

AbstractAim:To investigate whether luteolin, the major polyphenolic components of Lonicera japonica, has beneficial effects against lipopolysaccharide (LPS)-induced acute lung injury (ALI) and to determine whether the protective mechanism involves anti-inflammatory effects on neutrophils.Methods:ALI was induced with intratracheal instillation of LPS in mice. The level of ALI was determined by measuring the cell count and protein content in bronchoalveolar lavage (BAL) fluid. Neutrophils were stimulated with formyl-Met-Leu-Phe (fMLP) or LPS in vitro. Chemotaxis and superoxide anion generation were measured to evaluate neutrophil activation. The potential involvement of intracellular signaling molecules in regulating neutrophil activation was analyzed by using Western blot.Results:LPS induced ALI in mice, as evidenced with leukocyte infiltration and protein leakage into the lungs. Luteolin attenuated LPS-induced leukocyte infiltration and protein extravasation. In cell studies, luteolin attenuated the fMLP-induced neutrophil chemotaxis and respiratory burst (IC50 0.2±0.1 μmol/L and 2.2±0.8 μmol/L, respectively), but had a negligible effect on superoxide anion generation during phorbol myristate acetate stimulation. Furthermore luteolin effectively blocked MAPK/ERK kinase 1/2 (MEK), extracellular signal-regulated kinase (ERK), and Akt phosphorylation in fMLP- and LPS-stimulated neutrophils.Conclusion:These results indicate that luteolin has beneficial effects against LPS-induced ALI in mice, and the attenuation of neutrophil chemotaxis and respiratory burst by luteolin involves the blockade of MEK-, ERK-, and Akt-related signaling cascades.

Ginkgo biloba leaves extract (EGb 761) attenuates lipopolysaccharide-induced acute lung injury via inhibition of oxidative stress and NF-κB-dependent matrix metalloproteinase-9 pathway

Acute lung injury (ALI) presents high mortality and morbidity clinically and by far no effective preventive strategy has been established. Extract of Ginkgo biloba leaves, EGb 761, is a complex mixture that possesses several clinical beneficial effects such as anti-oxidation, anti-inflammation, anti-tumor, and cardioprotective property. With EGb 761 pretreatment, both lipopolysaccharide (LPS)-induced protein leakage and neutrophil infiltration, and LPS-induced inflammatory responses including increased myeloperoxidase (MPO) activity, lipid peroxidation, and metalloproteinase (MMP)-9 activity, were inhibited; LPS-suppressed activation of antioxidative enzymes (AOE) were reversed; and not only the phosphorylation of NF-κB but also the degradation of its inhibitor, IκB, were suppressed. These results suggested that the protection mechanism of EGb 761 is by inhibition of NFκB activation, possibly via the up-regulation of antioxidative enzymes. More studies are needed to further evaluate whether EGb 761 is a suitable candidate as an effective dietary strategy to reduce the incidence of endotoxin-induced ALI.

Luteolin Suppresses Inflammatory Mediator Expression by Blocking the Akt/NFκB Pathway in Acute Lung Injury Induced by Lipopolysaccharide in Mice

Acute lung injury (ALI), instilled by lipopolysaccharide (LPS), is a severe illness with excessive mortality and has no specific treatment strategy. Luteolin is an anti-inflammatory flavonoid and widely distributed in the plants. Pretreatment with luteolin inhibited LPS-induced histological changes of ALI and lung tissue edema. In addition, LPS-induced inflammatory responses, including increased vascular permeability, tumor necrosis factor (TNF)-α and interleukin (IL)-6 production, and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), were also reduced by luteolin in a concentration-dependent manner. Furthermore, luteolin suppressed activation of NFκB and its upstream molecular factor, Akt. These results suggest that the protection mechanism of luteolin is by inhibition of NFκB activation possibly via Akt.

Protective effect of rutin on LPS-induced acute lung injury via down-regulation of MIP-2 expression and MMP-9 activation through inhibition of Akt phosphorylation.

Lipopolysaccharide (LPS), also called endotoxin, is the important pathogen of acute lung injury (ALI), which is a clinical syndrome that still lacks effective therapeutic medicine. Rutin belongs to vitamin P and possesses various beneficial effects. In this study, we investigate the potential protective effects and the mechanisms of rutin on LPS-induced ALI. Pre-administration with rutin inhibited LPS-induced arterial blood gas exchange and neutrophils infiltration in the lungs. LPS-induced expression of macrophage inflammatory protein (MIP)-2 and activation of matrix metalloproteinase (MMP)-9 were suppressed by rutin. In addition, the inhibitory concentration of rutin on phosphorylation of Akt was similar as MIP-2 expression and MMP-9 activation. In conclusion, rutin is a potential protective agent for ALI via suppressing the blood gas exchange and neutrophil infiltration. The mechanism of rutin is down-regulation of MIP-2 expression and MMP-9 activation through inhibition of Akt phosphorylation.

Protective effect of wogonin on proinflammatory cytokine generation via Jak1/3-STAT1/3 pathway in lipopolysaccharide stimulated BV2 microglial cells.

Wogonin is a flavonoid compound which exhibits antioxidation, anti-inflammation, neuroprotection, and antitumorgenesis functions. However, the mechanism of how wogonin reduces proinflammatory cytokine generation in activated microglia is unclear. At present, we found wogonin inhibited lipopolysaccharide (LPS)-/interferon-γ (INF-γ)-induced generation of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Wogonin exhibited parallel inhibition on LPS-/INF-γ-induced expression of IL-6 and TNF-α messenger RNA at the same concentration range. LPS-/INF-γ-induced phosphorylation of signal transduction and transcription 1 and 3 (STAT1/3) were also inhibited by wogonin. Although wogonin expressed only weak inhibitory effect on LPS-/INF-γ-induced phosphorylation of Janus kinase-2 (Jak-2) and tyrosine kinase (Tyk)-2, it significantly attenuated the phosphorylation of Jak-1 and Jak-3. These results indicated that the blockade of IL-6 and TNF-α production by wogonin in LPS-/INF-γ-stimulated BV2 microglial cells was attributed mainly to the interference in Jak-1/-3-STAT1/3 signaling pathway.

Protective Effect of Ginkgo biloba leaves extract, EGb761, on Endotoxin-Induced Acute Lung Injury via a JNK- and Akt-Dependent NFκB Pathway

Acute lung injury (ALI) is a clinical syndrome mainly caused by Gram-negative bacteria which is still in need of an effective therapeutic medicine. EGb761, an extract of Ginkgo biloba leaves, has several bioeffects including anti-inflammation, cardioprotection, neuroprotection, and free radical scavenging. Preadministration of EGb761 inhibited lipopolysaccharide (LPS)-induced histopathological changes and exchange of arterial blood gas. In addition, LPS-induced expression of proinflammatory mediators, such as tumor necrosis factor (TNF)-α, interleukin (IL)-6, macrophage inflammatory protein (MIP)-2, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), were suppressed by EGb761. The activation of nuclear factor (NF)κB, a transcription factor of proinflammatory mediators, and phosphorylation of IκB, an inhibitor of NFκB, were also reduced by EGb761. Furthermore, we found the inhibitory concentration of EGb761 on phosphorylation of JNK and Akt was less than those of ERK and p38 MAPK. In conclusion, EGb761 is a potential protective agent for ALI, possibly via downregulating the JNK- and Akt-dependent NFκB activation pathway.

Wogonin attenuates endotoxin‐induced prostaglandin E2 and nitric oxide production via Src‐ERK1/2‐NFκB pathway in BV‐2 microglial cells

Microglia are the major component of intrinsic brain immune system in neuroinflammation. Although wogonin expresses anti‐inflammatory function in microglia, little is known about the molecular mechanisms of the protective effect of wogonin against microglia activation. The aim of this study was to evaluate how wogonin exerts its anti‐inflammatory function in BV2 microglial cells after LPS/INFγ administration. Wogonin not only inhibited LPS/ INFγ‐induced PGE2 and NO production without affecting cell viability but also exhibited parallel inhibition on LPS/INFγ‐induced expression of iNOS and COX‐2 in the same concentration range. While LPS/INFγ‐induced expression of P‐p65 and P‐IκB was inhibited by wogonin—only weak inhibition on P‐p38 and P‐JNK were observed, whereas it significantly attenuated the P‐ERK1/2 and its upstream activators P‐MEK1/2 and P‐Src in a parallel concentration‐dependent manner. These results indicated that the blockade of PGE2 and NO production by wogonin in LPS/INFγ‐stimulated BV2 cells is attributed mainly to interference in the Src‐MEK1/2‐ERK1/2‐NFκB‐signaling pathway.