Rungtip Soi-ampornkul

Interleukin-1β impairs brain derived neurotrophic factor-induced signal transduction

The expression of IL-1 is elevated in the CNS in diverse neurodegenerative disorders, including Alzheimers disease. The hypothesis was tested that IL-1 beta renders neurons vulnerable to degeneration by interfering with BDNF-induced neuroprotection. In trophic support-deprived neurons, IL-1 beta compromised the PI3-K/Akt pathway-mediated protection by BDNF and suppressed Akt activation. The effect was specific as in addition to Akt, the activation of MAPK/ERK, but not PLC gamma, was decreased. Activation of CREB, a target of these signaling pathways, was severely depressed by IL-1 beta. As the cytokine did not influence TrkB receptor and PLC gamma activation, IL-1 beta might have interfered with BDNF signaling at the docking step conveying activation to the PI3-K/Akt and Ras/MAPK pathways. Indeed, IL-1 beta suppressed the activation of the respective scaffolding proteins IRS-1 and Shc; this effect might involve ceramide generation. IL-1-induced interference with BDNF neuroprotection and signal transduction was corrected, in part, by ceramide production inhibitors and mimicked by the cell-permeable C2-ceramide. These results suggest that IL-1 beta places neurons at risk by interfering with BDNF signaling involving a ceramide-associated mechanism.

Protective effect of mangosteen extract against beta-amyloid-induced cytotoxicity, oxidative stress and altered proteome in SK-N-SH cells.

Beta-amyloid (A beta) plays a key role in the pathogenesis of Alzheimers disease (AD) by inducing neurotoxicity and cell death mainly through production of reactive oxygen species (ROS). Garcinia mangostana L. (mangosteen) has been recognized as a major source of natural antioxidants that could decrease ROS. However, its role in protection of A beta-induced cytotoxicity and apoptosis in neuronal cells remains unclear. We therefore examined such a protective effect of mangosteen extract (ME) by evaluating cell viability using MTT test, ROS level, caspase-3 activity, and cellular proteome. Treating SK-N-SH cells with 5-20 microM A beta((1-42)) for 24 h caused morphologically cytotoxic changes, decreased cell viability and increased ROS level, whereas preincubation with 50-400 microg/mL ME 30 min before the induction by A beta((1-42)) successfully prevented such cytotoxic effects in a dose-dependent manner (completely at 400 microg/mL). The A beta-induced increase in caspase-3 activity was also preventable by 400 microg/mL ME. Proteomic analysis using 2-D gel electrophoresis (n = 5 gels/group) followed by mass spectrometry revealed 63 proteins whose levels were significantly altered by A beta((1-42)) induction. Interestingly, changes in 10 proteins were successfully prevented by the ME pretreatment. In summary, we report herein the significant protective effects of ME against A beta-induced cytotoxicity, increased ROS, and increased caspase activity in SK-N-SH cells. Moreover, proteomic analysis revealed some proteins that might be responsible for these protective effects by ME. Further characterizations of these proteins may lead to identification of novel therapeutic targets for successful prevention and/or decreasing the severity of AD.

Protective Effects of Mangosteen Extract on H2O2-Induced Cytotoxicity in SK-N-SH Cells and Scopolamine-Induced Memory Impairment in Mice

Mangosteen extracts (ME) contain high levels of polyphenolic compounds and antioxidant activity. Protective effects of ME against β-amyloid peptide (Aβ), induced cytotoxicity have been reported. Here, we further studied the protective effects of ME against oxidative stress induced by hydrogen peroxide (H2O2) and polychlorinated biphenyls (PCBs), and demonstrated the protection against memory impairment in mice. The cytoprotective effects of ME were measured as cell viability and the reduction in ROS activity. In SK-N-SH cell cultures, 200 μg/ml ME could partially antagonize the effects of 150 or 300 µM H2O2 on cell viability, ROS level and caspase-3 activity. At 200, 400 or 800 µg/ml, ME reduced AChE activity of SK-N-SH cells to about 60% of the control. In vivo study, Morris water maze and passive avoidance tests were used to assess the memory of the animals. ME, especially at 100 mg/kg body weight, could improve the animal’s memory and also antagonize the effect of scopolamine on memory. The increase in ROS level and caspase-3 activity in the brain of scopolamine-treated mice were antagonized by the ME treatment. The study demonstrated cytoprotective effects of ME against H2O2 and PCB-52 toxicity and having AChE inhibitory effect in cell culture. ME treatment in mice could attenuate scopolamine-induced memory deficit and oxidative stress in brain.

Interleukin -1β interferes with signal transduction induced by neurotrophin-3-in cortical neurons

It was previously observed that IL-1beta interferes with BDNF-induced TrkB-mediated signal transduction and protection of cortical neurons from apoptosis evoked by deprivation from trophic support [Tong L., Balazs R., Soiampornkul R., Thangnipon W., Cotman C.W., 2007. Interleukin-1beta impairs brain derived neurotrophic factor-induced signal transduction. Neurobiol. Aging]. Here we investigated whether the effect of the cytokine on neurotrophin signaling is more general. The influence of IL-1beta on NT-3 signaling was therefore studied under conditions when NT-3 primarily activated the TrkC receptor. The cytokine reduced NT-3-induced activation of MAPK/ERK and Akt, but did not interfere with Trk receptor autophosphorylation. IL-1beta reduced tyrosine phosphorylation of the docking proteins, IRS-1 and Shc, which convey receptor activation to the downstream protein kinase cascades. These are the steps that are also inhibited by IL-1beta in BDNF-induced signal transduction. The functional consequences of the effect of IL-1beta on NT-3 signaling were severe, as NT-3 protection of the trophic support-deprived cortical neurons was abrogated. In view of the role in the maintenance and plasticity of neurons of ERK, Akt and CREB, which are activated by neurotrophins, elevated IL-1beta levels in the brain in Alzheimers disease and other neurodegenerative diseases might contribute to the decline in cognitive functions before the pathological signs of the disease develop.

Protective role of N-trans-feruloyltyramine against β-amyloid peptide-induced neurotoxicity in rat cultured cortical neurons

Enhanced oxidative stress and inflammation play important roles in the pathogenesis of Alzheimers disease (AD). Amyloid β-peptide (Aβ), a major component of amyloid plaques, is considered to have a causal role in the development and progress of AD by being the initiator of a pathological cascade leading to oxidative stress. The present study investigated the effect of N-trans-feruloyltyramine (NTF) purified from Polyalthia suberosa, an alkaloid shown to protect against oxidative stress and cell death. Pre-treatment of rat primary cortical cell cultures with 25-250μM NTF significantly attenuated 10μM Aβ(1-42)-induced neuronal death in a dose-dependent manner. Apoptotic cell death was demonstrated morphologically as well as by detection of the presence of activated caspase-3 and Bax, levels of which could be reduced by NTF pre-treatment. NTF also reduced production of reactive oxygen species induced by Aβ(1-42). These findings suggest that the protective effect of NTF against Aβ(1-42)-induced neuronal death might be due to its antioxidative property.

N-benzylcinnamide protects rat cultured cortical neurons from β-amyloid peptide-induced neurotoxicity.

The pathogenesis of Alzheimers disease involves an amyloid β-peptide (Aβ)-induced cascade of elevated oxidative damage and inflammation. The present study investigates the protective effects and the underlying mechanisms of N-benzylcinnamide (PT-3), purified from Piper submultinerve. Against Aβ-induced oxidative stress and inflammation in rat primary cortical cell cultures. Pre-treatment with 10-00nM PT-3 significantly attenuated neuronal cell death induced by 10μM Aβ1-42. PT-3 was found to enhance cell viability through a significant reduction in the level of reactive oxygen species, down-regulated expression of pro-apoptotic activated caspase-3 and Bax, increased expression of anti-apoptotic Bcl-2, and mitigation of Aβ-induced morphological alterations. Regarding its effects on inflammatory responses, PT-3 pre-treatment decreased the expression of pro-inflammatory cytokines IL-1β and IL-6. The mechanisms of PT-3 neuronal protection against inflammation may be associated with the mitogen-activated protein kinases (MAPK) pathway. Aβ1-42-induced phosphorylation of JNK and p38 MAPK was inhibited by pretreatment with PT-3 in a dose-dependent manner. However, phosphorylation of ERK1/2 was not affected by either PT-3 or Aβ1-42. PT-3 did not stimulate Akt phosphorylation, which was inhibited by Aβ1-42. These findings suggest that PT-3 protects neurons from Aβ1-42-induced neurotoxicity through its anti-apoptotic, anti-oxidative, and anti-inflammatory properties with inhibition of JNK and p38 MAPK phosphorylation as the potential underlying mechanism.

Neuroprotective effects of diarylpropionitrile against β-amyloid peptide-induced neurotoxicity in rat cultured cortical neurons

Alzheimers disease is a major cause of dementia in the elderly that involves a β-amyloid peptide (Aβ)-induced cascade of an increase in oxidative damage and inflammation. The present study demonstrated the neuroprotective effects of diarylpropionitrile (DPN), a non-steroidal estrogen receptor β selective ligand, against 10 μM Aβ1-42-induced oxidative stress and inflammation in primary rat cortical cell culture. Pre-treatment with 1-100 nM DPN significantly decreased neuronal cell death by increasing cell viability through a significant attenuation in the reactive oxygen species level, downregulation of pro-apoptotic activated caspase-3 and Bax, and upregulation of anti-apoptotic Bcl-2, thereby mitigating apoptotic morphological alterations. DPN pre-treatment decreased the expression levels of pro-inflammatory cytokines IL-1β and IL-6 through attenuation of Aβ1-42-induced phosphorylation of mitogen-activated protein kinases JNK and p38. In addition, DPN enhanced ERK1/2 and Akt phosphorylation depressed by Aβ1-42. These findings suggest that DPN protects neurons from Aβ1-42-induced neurotoxicity through a variety of mechanisms, ranging from anti-oxidation, anti-apoptosis, through to anti-inflammation.

The platelet amyloid precursor protein ratio as a diagnostic marker for Alzheimer’s disease in Thai patients

The platelet amyloid precursor protein (APP) ratio has recently been shown to be a promising diagnostic marker for Alzheimers disease (AD). To evaluate its usefulness in Thai patients, platelet APP was analyzed by immunoblotting. The APP ratio was calculated as the ratio of the combined band density of the 120-kD and 130-kD isoforms compared to that of the 110-kD isoform. The mean ages (and ranges) of 27 normal and 13 AD-affected subjects were 68.3 (60-84) and 79.3 (70-97) years, respectively. The Thai Mental State Examination (TMSE) scores demonstrated that the AD patients had significantly poorer cognitive functions than the normal subjects, with mean TMSE scores of 20.3 and 27.6 (maximum score of 30 points), respectively (p<0.05). The platelet APP ratios of the AD patients were significantly lower than those of normal subjects: values (mean ± standard deviation) were 7.32 ± 1.29 and 9.13 ± 3.00, respectively (p<0.05) for AD patients and normal subjects. However, the ranges of the APP ratios from both groups markedly overlapped, which precluded the establishment of a cutoff level to differentiate between the AD and normal subjects. In addition, no significant correlations were observed between the platelet APP ratio and the TMSE score or between the APP ratio and the serum cholesterol in this study, in contrast to previous reports.

Potential role of N-benzylcinnamide in inducing neuronal differentiation from human amniotic fluid mesenchymal stem cells

Neurodegenerative disorders are characterized by chronic and progressive loss of neurons in structure and function related to aging, such as Alzheimers disease, the latter characterized by the degeneration of cholinergic neurons in basal forebrain connected to the cerebral cortex and hippocampus. Amniotic fluid mesenchymal stem cells (AF-MSCs) have been proposed as one of the candidates for stem cell therapy of nervous system disorders. This study demonstrates that incubation of AF-MSCs, obtained from 16 to 20 week pregnant women, with 10ng/ml bone morphogenetic protein (BMP)-9 for 48h in conditioned medium resulted in transdifferentiation to cholinergic neuronal-like cells. This phenomenon could also be obtained with N-benzylcinnamide (PT-3). Pre-treatment for 1h with 10nM PT-3 augmented BMP-9 transdifferentiation effect, elevated βIII-tubulin cell numbers and fluorescence intensity of immunoreactive ChAT, ameliorated BMP-9-related production of reactive oxygen species and enhanced anti-apoptosis status of the neuronal-like cells. The transdiffirentiation process was accompanied by increased p53 but decreased Notch1 and SIRT1 (p53 deacetylase) levels, and activation of p38, ERK1/2 MAPK, and PI3K/Akt pathways, in concert with inactivation of JNK, all of which were accentuated by PT-3 pre-treatment. These findings suggest that N-benzylcinnamide may provide a useful adjuvant in BMP-9-induced transdifferentiation of AFMSCs into ultimately cholinergic neurons.

Regulation of cytotoxicity and apoptosis-associated pathways contributes to the enhancement of efficacy of cisplatin by baicalein adjuvant in human A549 lung cancer cells

Scutellaria baicalensis (SB; Chinese name, huangqin) is widely used in Chinese medicine as a traditional adjuvant in the chemotherapy of lung and liver cancer. Baicalein is one of the bioactive flavonoid components isolated from the root of SB. The present study aimed to observe the effect of baicalein, in combination with platin-based systemic chemotherapy (cisplatin), on cytotoxicity and apoptosis of human A549 lung cancer cells. The cell cultures were treated with baicalein, cisplatin, or a combination of the two. Cell viability and cytotoxicity was assayed by XTT, and cell apoptosis was measured by flow cytometry. The apoptosis-associated proteins were detected by western blot analysis. The cytokines in the culture supernatant were detected by ELISA. The present study revealed that cisplatin and the baicalein-cisplatin combination inhibited viability and promoted cytotoxicity of A549 cells. Cisplatin, baicalein and baicalein-cisplatin combination treatments were effective in the promotion of apoptosis of A549 cells. Baicalein and baicalein-cisplatin combination treatments also inhibited B cell lymphoma-2 (Bcl-2) and increased Bcl-2-associated X protein (Bax) expression. Additionally, cisplatin, baicalein and the baicalein-cisplatin combination promoted caspase-3 expression. Furthermore, the baicalein-cisplatin combination suppressed the secretion of interleukin-6, and baicalein and the combination of baicalein cisplatin decreased the secretion of tumor necrosis factor-α of A549 cells. The present study concluded that baicalein combined with cisplatin induced cytotoxicity and apoptosis of A549 cells, and such activity may be associated with the regulation of Bcl-2, Bax and caspase-3, indicating a promising alternative method for lung cancer.