Midori Suenaga

Vizantin Inhibits Endotoxin-Mediated Immune Responses via the TLR 4/MD-2 Complex

Vizantin has immunostimulating properties and anticancer activity. In this study, we investigated the molecular mechanism of immune activation by vizantin. THP-1 cells treated with small interfering RNA for TLR-4 abolished vizantin-induced macrophage activation processes such as chemokine release. In addition, compared with wild-type mice, the release of MIP-1β induced by vizantin in vivo was significantly decreased in TLR-4 knockout mice, but not in TLR-2 knockout mice. Vizantin induced the release of IL-8 when HEK293T cells were transiently cotransfected with TLR-4 and MD-2, but not when they were transfected with TLR-4 or MD-2 alone or with TLR-2 or TLR-2/MD-2. A dipyrromethene boron difluoride–conjugated vizantin colocalized with TLR-4/MD-2, but not with TLR-4 or MD-2 alone. A pull-down assay with vizantin-coated magnetic beads showed that vizantin bound to TLR-4/MD-2 in extracts from HEK293T cells expressing both TLR-4 and MD-2. Furthermore, vizantin blocked the LPS-induced release of TNF-α and IL-1β and inhibited death in mice. We also performed in silico docking simulation analysis of vizantin and MD-2 based on the structure of MD-2 complexed with the LPS antagonist E5564; the results suggested that vizantin could bind to the active pocket of MD-2. Our observations show that vizantin specifically binds to the TLR-4/MD-2 complex and that the vizantin receptor is identical to the LPS receptor. We conclude that vizantin could be an effective adjuvant and a therapeutic agent in the treatment of infectious diseases and the endotoxin shock caused by LPS.

Reversal of temperature-induced conformational changes in the amyloid-beta peptide, Aβ40, by the β-sheet breaker peptides 16–23 and 17–24

Background and purpose:  Aggregates of the protein amyloid‐beta (Aβ) play a crucial role in the pathogenesis of Alzheimers disease (AD). Most therapeutic approaches to AD do not target Aβ, so determination of the factor(s) that facilitate aggregation and discovering agents that prevent aggregation have great potential therapeutic value.

In vitro antitrypanosomal activity of the cyclodepsipeptides, cardinalisamides A–C, from the insect pathogenic fungus Cordyceps cardinalis NBRC 103832

During the search for new antitrypanosomal drug leads, three new antitrypanosomal compounds, cardinalisamides A–C (1–3), were isolated from cultures of the insect pathogenic fungus Cordyceps cardinalis NBRC 103832. Their structures were elucidated using MS analyses and extensive 2D-heteronuclear NMR. The absolute configurations of 1–3 were addressed by chemical degradation and Marfey’s analysis. 1–3 showed in vitro antitrypanosomal activity against Trypanosoma brucei brucei with IC50 values of 8.56, 8.65 and 8.63 μg ml−1, respectively.

Opaliferin, a new polyketide from cultures of entomopathogenic fungus Cordyceps sp. NBRC 106954.

Opaliferin, a polyketide with a unique partial structure in which a cyclopentanone and tetrahydrofuran were connected with an external double bond, was isolated from the insect pathogenic fungus Cordyceps sp. NBRC 106954. The structure and relative configuration of opaliferin were determined by spectroscopic analysis and X-ray crystallography. The absolute configuration was established by anomalous dispersion effects in X-ray diffraction measurements on the crystal of di(p-bromobenzoyl) ester of opaliferin. A plausible biosynthetic pathway for opaliferin is proposed.

Effects of 8-Residue Beta Sheet Breaker Peptides on Aged Aβ40 – Induced Memory Impairment and Aβ40 Expression in Rat Brain and Serum Following Intraamygdaloid Injection

Amyloidβ-protein (Aβ) assembly into toxic fibrillar structures is seminal in development of senile plaques, the pathological hallmark of Alzheimers disease. Blocking this process could have a therapeutic value. β-sheet breaker peptides (βSBP) decrease Aβ fibrillogenesis and neurotoxicity by preventing or dissolving misfolded Aβ aggregates. The present study investigated the effects of βSBPs on Aβ40-related neuropathology, memory impairment in 8-armed radial maze and expression of Aβ40 in brain and serum. Aβ40 was injected into amygdaloid nucleus followed 8 days later by octapeptideβSBPs 15-22, 16-23 and 17-24. Aβ40 was detected not only in amygdala, but also in serum. Aβ40 induced cellular changes in amygdala and additionally in hippocampus. Aβ40 decreased correct choices, whereas increased errors (both number of arms revisited and total number of revisits) and latency of completing the maze test. The βSBPs decreased Aβ40-induced pathological changes, memory impairment and Aβ40 expression in serum. The βSBP15-22 distinctively decreased the total errors on day 14. The present results show that octapeptide βSBPs corrected Aβ40-induced memory impairment, and support investigation of βSBPs as a promising treatment of diseases characterized by neurodegeneration and memory impairment such as Alzheimers disease.

Novel neurotrophic phenylbutenoids from Indonesian ginger Bangle, Zingiber purpureum.

Two new curcuminoids 1 and 2, and a new phenylbutenoid dimer 3, were isolated from Bangle (Zingiber purpureum). Their structures were determined on the basis of comprehensive spectroscopic data and their biogenetic pathway. Compounds 1 and 2 are the first example of curcumin coupled with phenylbutenoid. Compounds 1 and 2 promoted neurite outgrowth of NGF-mediated PC12 cells at concentrations ranging from 1 to 10 μM. In addition, compound 1 was found to accelerate the prevention of Aβ42 aggregation.

Serum vitamin D in patients with mild cognitive impairment and Alzheimer's disease

To determine the relevance of Mini‐Mental State Examination (MMSE), serum 25‐hydroxyvitamin D (25(OH)D3), and 1,25(OH)2D3 concentrations to mild cognitive impairment (MCI) and various stages of Alzheimers disease (AD).

Different Effect of Vitamin D 2 and Vitamin D 3 on Amyloid-β40 Aggregation In Vitro

The seeding of amyloid-β 40 (Aβ40) oligomers from monomers is the initial step of Aβ aggregation, and many reports have suggested that cholesterol enhances this step. We studied the potential of secosteroid vitamin D derivatives for Aβ40 aggregation in vitro. The quartz-crystal microbalance technique demonstrated that vitamin D3 does not show any effect on Aβ40 aggregation while vitamin D2 promoted it and docking simulation but that vitamin D2 has high potential in this regard. Thus, stacking of the Phe19 benzene ring in Aβ40 and the C22-C23 double bond in vitamin D2 may alter the energy of these molecules. Electron microscopy revealed the potential of vitamin D2 to increase Aβ40 aggregation. Thioflavin-T assays indicated that Vitamin D2 induced increased fluorescence at 490 nm, as typically observed for amyloid fibrils but also for protofibrils; in both cases this reflects of the increase of β-sheet contents. Aβ40 aggregation was further confirmed in ELISA, SDS-PAGE and dot blot analysis which revealed changes in protease K resistance. These results suggest a possible mechanism, of how vitamin D2 could increase Aβ40 aggregation and the docking simulation explains, why the same is not observed with vitamin D3.

Vitamin D 2 interacts with Human PrP(c) (90-231) and breaks PrP(c) oligomerization in vitro.

PrPsc, the pathogenic isoform of PrPc, can convert PrPc into PrPsc through direct interactions. PrPc oligomerization is a required processing step before PrPsc formation, and soluble oligomers appear to be the toxic species in amyloid-related disorders. In the current study, direct interactions between vitamin D2 and human recombinant PrPc (90–231) were observed by Biacore assay, and 3F4 antibody, specific for amino acid fragment 109–112 of PrPc, inhibited this interaction. An ELISA study using3F4 antibody showed that PrPc (101–130), corresponding sequence to human PrP, was affected by vitamin D2, supporting the results of Biacore studies and suggesting that the PrPc sequence around the 3F4 epitope was responsible for the interaction with vitamin D2. Furthermore, the effects of vitamin D2 on disruption of PrPc (90–231) oligomerization were elucidated by dot blot analysis and differential protease k susceptibilities. While many chemical compounds have been proposed as potential therapeutic agents for the treatment of scrapie, most of these are toxic. However, given the safety and blood brain barrier permeability of vitamin D2, we propose that vitamin D2 may be a suitable agent to target PrPc in the brain and therefore is a potential therapeutic candidate for prion disease.

Monocytic elastase-mediated apolipoprotein-E degradation: Potential involvement of microglial elastase-like proteases in apolipoprotein-E proteolysis in brains with Alzheimers disease.

Impaired clearance of soluble Aβ (amyloid-β) promotes Aβ aggregation in brains with Alzheimers disease (AD), while apolipoprotein-E (ApoE) in microglia mediates Aβ clearance. We studied the protease responsible for ApoE(4) degradation in human peripheral monocyte extracts, which are from the same lineage as microglia. We detected the hydrolytic activity for ApoE(4) in high-salt extracts with 2 M NaCl and found that the activity was inhibited by a serine protease inhibitor and an elastase-specific inhibitor, but not by other protease inhibitors. The extracts exhibited higher activity for the elastase substrate, and we followed the activity with ion-exchange and gel-filtration chromatography. Through silver staining, we partially purified a protein of 28 kDa, which was clarified as elastase by liquid chromatography-tandem mass spectrometry. These observations suggest that elastase is the key protease for ApoE(4) degradation. We also detected ApoE(4) hydrolytic activity in high-salt extracts in mouse microglial (BV-2) cell lysates, and showed that the ApoE(4) fragments by the BV-2 extracts differed from the fragments by the monocyte extracts. Though the ApoE(4) degradation by the extracts was not inhibited with elastase-specific inhibitors, it was inhibited by an elastase-specific monoclonal antibody, suggesting that elastase-like proteases in microglia differ from those of monocytes. Immunohistochemistry revealed that both elastase and ApoE were expressed in the senile plaques of brains with AD. In vitro studies also disclosed the localization of elastase in the microglial cell line, BV-2. Our results suggest that elastase-like proteases in the microglial cells surrounding Aβ plaques are responsible for ApoE degradation in the brain.