Garcinoic acid prevents β-amyloid (Aβ) deposition in the mouse brain

Garcinoic acid (GA or δ-T3-13'COOH), is a natural vitamin E metabolite that has preliminarily been identified as a modulator of nuclear receptors involved in β-amyloid (Aβ) metabolism and progression of Alzheimer's disease (AD). In this study, we investigated GA's effects on Aβ oligomer formation and deposition. Specifically, we compared them with those of other vitamin E analogs and the soy isoflavone genistein, a natural agonist of peroxisome proliferator-activated receptor γ (PPARγ) that has therapeutic potential for managing AD. GA significantly reduced Aβ aggregation and accumulation in mouse cortical astrocytes. Similarly to genistein, GA up-regulated PPARγ expression and apolipoprotein E (ApoE) efflux in these cells with an efficacy that was comparable with that of its metabolic precursor δ-tocotrienol and higher than those of α-tocopherol metabolites. Unlike for genistein and the other vitamin E compounds, the GA-induced restoration of ApoE efflux was not affected by pharmacological inhibition of PPARγ activity, and specific activation of pregnane X receptor (PXR) was observed together with ApoE and multidrug resistance protein 1 (MDR1) membrane transporter up-regulation in both the mouse astrocytes and brain tissue. These effects of GA were associated with reduced Aβ deposition in the brain of TgCRND8 mice, a transgenic AD model. In conclusion, GA holds potential for preventing Aβ oligomerization and deposition in the brain. The mechanistic aspects of GA's properties appear to be distinct from those of other vitamin E metabolites and of genistein

3-hydroxy-L-kynurenamine is an immunomodulatory biogenic amine

Tryptophan catabolism is a major metabolic pathway utilized by several professional and non-professional antigen presenting cells to maintain immunological tolerance. Here we report that 3-hydroxy-l-kynurenamine (3-HKA) is a biogenic amine produced via an alternative pathway of tryptophan metabolism. In vitro, 3-HKA has an anti-inflammatory profile by inhibiting the IFN-gamma mediated STAT1/NF-kappa Beta pathway in both mouse and human dendritic cells (DCs) with a consequent decrease in the release of pro-inflammatory chemokines and cytokines, most notably TNF, IL-6, and IL12p70. 3-HKA has protective effects in an experimental mouse model of psoriasis by decreasing skin thickness, erythema, scaling and fissuring, reducing TNF, IL-1 beta, IFN-gamma, and IL-17 production, and inhibiting generation of effector CD8(+) T cells. Similarly, in a mouse model of nephrotoxic nephritis, besides reducing inflammatory cytokines, 3-HKA improves proteinuria and serum urea nitrogen, overall ameliorating immune-mediated glomerulonephritis and renal dysfunction. Overall, we propose that this biogenic amine is a crucial component of tryptophan-mediated immune tolerance. 3-hydroxy-L-kynurenamine (3-HKA) is a metabolite deriving from a lateral pathway of tryptophan catabolism. Here the authors identify 3-HKA as a biogenic amine and show it has anti-inflammatory properties that can protect mice against psoriasis and nephrotoxic nephritis.Peer reviewe

Identification of additional genes required for O-antigen biosynthesis in Vibrio cholerae O1

The cloning and expression of the genes encoding the Vibrio cholerae O1 lipopolysaccharide O antigen in a heterologous host have been described previously (P. A. Manning, M. W. Heuzenroeder, J. Yeadon, D. I. Leavesley, P. R. Reeves, and D. Rowley, Infect. Immun. 53:272-277, 1986). It was thus assumed that all the genes required for O-antigen expression were located on a 20-kb SacI restriction fragment. We present evidence for a number of other as yet undescribed genes that are essential for O-antigen biosynthesis in V. cholerae O1 and that these genes are somehow complemented in Escherichia coli K-12. The two genes termed Vibrio cholerae rfbV and rfbU are transcribed in the opposite orientation from the rest of the rfb operon, whereas the galE dehydratase and rfbP (Salmonella enterica) homologs, designated ORF35x7 and rfbW, respectively, are transcribed in the same orientation. The evidence presented here, using chromosomal insertion mutants, clearly shows that the three genes now designated rfbV, rfbU, and rfbW appear to be accessory rfb genes and are essential for O-antigen biosynthesis in V. cholerae but that ORF35x7 is not

Characterization of the Vibrio cholerae E1 Tor lipase operon lipAb and a protease gene downstream of the hly region

We have cloned and sequenced a region encoding a lipase operon and a putative, previously uncharacterized metalloprotease of Vibrio cholerae O1. These lie downstream of hlyA and hlyB, which encode the El Tor hemolysin and methyl-accepting chemotactic factor, respectively. Previous reports identified the hlyC gene downstream of hlyAB, encoding an 18.3-kDa protein. However, we now show that this open reading frame (ORF) encodes a 33-kDa protein, and since the amino acid sequence is highly homologous to the triacylglyceride- specific lipase of Pseudomonas spp., hlyC has been renamed lipA. LipA contains the highly conserved pentapeptide and catalytic triad amino acid regions of the catalytic sites of other lipases. The region downstream of lipA has been sequenced and has revealed ORFs lipB and prtV. The amino acid sequence of lipB is homologous to those of the accessory lipase proteins (lipase-specific foldase) required by Pseudomonas and various other bacterial species for the production of mature active lipase, and in agreement with this, we show that both lipA and lipB are required to restore a lipase-deficient lipA null mutant of V. cholerae. The intergenic stop codon for lipA overlaps the ribosome-binding site for lipB, and a stem-loop resembling a rho-independent terminator is present immediately downstream from lipB, suggesting that lipA and lipB form a lipase operon in V. cholerae. prtV lies downstream of lipAB but is transcribed in the opposite direction and is predicted to share the same putative transcriptional terminator with lipAB. The zinc-binding and catalytic domains conserved among many metalloproteases are present in PrtV, which is highly homologous to the immune inhibitor A (InA) metalloprotease of Bacillus thuringiensis. PrtV was visualized as approximately 102 kDa, which is consistent with the coding capacity of the gene. The genetic organization of this region suggests that it is possibly part of a pathogenicity island, encoding products capable of damaging host cells and/or involved in nutrient acquisition by V. cholerae. However, neither lipA nor prtV null mutants were attenuated in the infant mouse model, nor did they exhibit reduced colonization potential compared with wild type in competition experiments.Monica A. Ogierman, Angelo Fallarino, Tanja Riess, Susan G. Williams, Stephen R. Attridge, and Paul A. Mannin

Effect of insulin on airway responsiveness in patients with type 2 diabetes mellitus: A cohort study

BACKGROUND: The correlation between low insulin levels and a decreased sensitivity of the muscarinic receptor has been shown on induced-diabetes animal models. We designed a cohort study with the aim of evaluating the effects of insulin therapy on airway responsiveness (AR) in human patients with type 2 diabetes mellitus. METHODS: We enrolled 92 patients with type 2 diabetes who had switched from oral anti-diabetic therapy to treatment by insulin subcutaneous injection. Patients were administered the methacholine challenge test (MCT) at time 0 (pre-insulin therapy) and at intervals of 15, 30, 90, 180, and 360 days after insulin treatment. The decline of forced expiratory volume in 1 second (FEV(1))% from baseline (Delta FEV(1)) in response to inhaled methacholine (MCH) was determined to assess airway hyper-responsiveness (AHR). RESULTS: A total of 81 patients (18 women and 63 men) completed the study. Their mean age was 58 +/- 7 years and the mean duration of disease was 13.5 +/- 7.7 years. The mean decrease of FEV(1) at pre-insulin assessment was 2.96 +/- 2.6%. Compared with the pre-insulin value, a significant increase of Delta FEV(1) was observed at 15, 30, and 90 days after treatment (6.25%, CI 95% 5.4 to 7.2, p = 0.0005; 7.64%, CI 95% 6.6 to 8.1, p < 0.001; 6.45%, CI 95% 5.5 to 7.3, p = 0.0004, respectively), while after 180 and 360 days AR was similar to pre-insulin values (Delta FEV(1), 3.62%, CI 95% 2.7 to 3.5 and 3.11%, CI 95% 7.9 to 9.3, respectively). CONCLUSIONS: The finding of an increased AR in patients with type 2 diabetes during the first 3 months of insulin therapy may underline the importance of monitoring pulmonary function and respiratory symptoms in patients switching from oral anti-diabetic drugs to insulin therapy, especially in the subset of individuals with respiratory disorders

Circulating monocyte oxidative activity is increased in patients with type 2 diabetes and erectile dysfunction

Purpose: We investigated the relationship between oxidative stress and diabetic erectile dysfunction. Materials and Methods: A total of 23 patients with a mean SD age of 56.7 +/- 5.6 years, a history of type 2 diabetes for 10.0 +/- 8.3 years and erectile dysfunction, as tested by the International Index of Erectile Function questionnaire, but without vascular and neurological complications, and 15 age matched patients with diabetes without erectile dysfunction were recruited. Circulating monocyte oxidative activity by cytofluorometry, and endothelin-1, intercellular adhesion molecule-1, plasminogen activator inhibitor-1 by enzyme linked immunosorbent assay were evaluated in all patients in the study. Results: Monocyte free radical production, and total and low density lipoprotein cholesterol were higher in patients with than in those without erectile dysfunction (p < 0.03, < 0.02 and < 0.05, respectively). In all patients the International Index of Erectile Function score inversely correlated with low density lipoprotein (p < 0.05), while in patients with erectile dysfunction it negatively correlated with age (p < 0.03), body mass index (p < 0.02), endothelin-1 (p < 0.02) and intercellular adhesion molecule-1 (p < 0.05). Endothelin-1, intercellular adhesion molecule-1 and plasminogen activator inhibitor-1 were not different in patients with diabetes with and without erectile dysfunction. Conclusions: In men with type 2 diabetes who have erectile dysfunction but are asymptomatic for cardiovascular disease oxidative activation of monocytes is increased and it is related to other risk factors of endothelial dysfunction

Garcinoic Acid Is a Natural and Selective Agonist of Pregnane X Receptor

Pregnane X receptor (PXR) is a master xenobiotic-sensing transcription factor with a key role in drug metabolism and disposition. Its activity regulates a number of physiological processes in the liver and intestine, and it is now a validated target for human diseases associated with inflammation and dysregulation of the immune system. The identification of chemical probes to investigate the therapeutic relevance of the receptor is still highly desired. In fact, currently available PXR ligands are not highly selective and can exhibit toxicity and/or potential off-target effects. In this study, we have identified the naturally-occurring garcinoic acid as a selective and efficient PXR agonist. The properties of garcinoic acid as a specific PXR agonist was demonstrated using different approaches - screening on a panel of nuclear receptors, physical and thermodynamic evaluation of binding affinity, and co-crystallization study. Cytotoxicity assays, transcriptional and functional experiments were carried out in human liver cells, in mouse liver and gut tissue to prove compound activity and target engagement. Taken together, these data support the conclusion that garcinoic acid efficiently activates PXR and may prove to be an amenable lead toward the development of differentially acting PXR regulating compounds

Cloning and characterization of a novel haemolysin in Vibrio cholerae O1 that does not directly contribute to the virulence of the organism

Copyright © 2002 Society for General MicrobiologyAngelo Fallarino, Stephen R. Attridge, Paul A. Manning and Tony Focaret