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At least 1,099 records · Page 61Linked to original sources
PubMed2006

Activity-based matrix metallo-protease enrichment using automated, inhibitor affinity extractions.

An automated inhibitor affinity extraction method for the activity-based enrichment of matrix metallo-proteases (MMPs) is presented. Samples containing purified MMP-12 were first extracted at different flow rates in a syringe pump setup, using cartridges packed with an MMP inhibitor affinity sorbent based on an immobilized hydroxamic acid containing peptide (PLG-NHOH) with mumol/L MMP affinity. Faster extractions, a reduced number of manual manipulations, and higher extraction yields (98.9%-99.3%) were obtained over the whole flow rate range compared to batch extractions. Application of the method to synovial fluid from a rheumatoid arthritis patient followed by gelatin-zymography revealed a strong enrichment of distinct MMPs from this biological sample that were not clearly visible in the original sample. The use of an auto-sampler and a solid-phase extraction (SPE) workstation allowed full automation of the extraction procedure with the potential for on-line coupling to further sample preparation and analytical steps. MMP-12 extractions were optimized showing that ligand density is an important factor with a clear extraction yield optimum around 5 to 7.5 mmol/L. Conditioning of the stationary phase for 1 week prior to use resulted in a further slight increase in extraction yield. Under optimal conditions, an extraction yield of 99.5% was reached with a cartridge contact time of only 13 s for MMP-12. The efficacy of the extraction method for activity-based MMP profiling was further improved by the use of a broad-spectrum MMP inhibitor with nmol/L affinity (TAPI-2). This resulted in an increased extraction yield for all tested MMPs. For MMP-1, -7, -8, -10, -12, and -13 extraction yields of at least 98.8% were obtained, while for MMP-9 (full length and catalytic domain) an extraction yield of at least 96.1% was reached.

Adsorption↗
PubMedDate not supplied

A chemical comparison of methanesulfonyl fluoride with organofluorophosphorus ester anticholinesterase compounds.

The chemical reactivity and physical properties of methanesulfonyl fluoride (MSF) were quantitatively measured for direct comparison with those of isopropyl methylphosphonofluoridate (GB, sarin) and diisopropyl phosphorofluoridate (DFP). The chemistry involved reaction rate constant measurements of MSF hydrolysis and for reactions with phenolic, amine, oxime, hydroxamic acid, phenyl N-hydroxycarbamate, and hydroxylamine compounds and cupric imidazole and bipyridyl complexes. Analogous chemistry with GB and DFP occurred only for the nucleophilic reactions. MSF was substantially less reactive toward interactions involving hydrogen bonding, cupric complex coordination, and quaternary amine formation. Physical characterization included water solubility, vapor pressure, heat of vaporization, solubility parameter, hydrogen bond basicity, UV, IR, and NMR measurements. MSF is a much weaker hydrogen bond acceptor than the phosphorus esters. The hydrogen bond basicity beta-scale measurement provides a key insight to the chemical reactivity divergence of MSF and DFP or GB. Its unexpectedly low value is interpreted that MSF does not possess a site with sufficient basicity to be protonated by strong acid, to enter into hydrogen bonding, or for coordination with the cupric ion.

Cholinesterase Inhibitors↗
PubMedDate not supplied

Activation of the carcinogen N-hydroxy-N-(2-fluorenyl)benzamide via chemical and enzymatic oxidations. Comparison to oxidations of the structural analogue N-hydroxy-N-(2-fluorenyl)acetamide.

Chemical or enzymatic oxidations of the carcinogen N-hydroxy-N-(2- fluorenyl)benzamide (N-OH-2-FBA) were investigated under the conditions facilitating one-electron oxidation or oxidative cleavage of N-hydroxy-N-(2-fluorenyl)acetamide (N-OH-2-FAA). HPLC methods were developed for separation and quantitation of the above hydroxamic acids and their respective oxidation products. To identify the products of oxidation of N-OH-2-FBA, N-(benzoyloxy)-2-FBA (N-BzO-2-FBA) was synthesized and shown to undergo ortho rearrangement to 1- and 3-BzO-2-FBA. Oxidation of N-OH-2-FBA (4.88 mM) with alkaline K3Fe(CN)6 in benzene was complete and yielded equimolar amounts of 2-nitrosofluorene (2-NOF) and the ester (chiefly N-BzO-2-FBA), indicative of one-electron oxidation to nitroxyl free radical which undergoes bimolecular dismutation. However, one-electron oxidation of N-OH-2-FBA (30 or 10 microM) by horseradish peroxidase/H2O2 at pH 7 or myeloperoxidase/H2O2 at pH 6.5 yielded only approximately 10% as much product as N-OH-2-FAA (30 microM). The addition of 0.1 mM Br- +/- 0.1 M Cl- at pH 4 to 6.5 increased 2-NOF formation in MPO/H2O2-catalyzed oxidations. Simulations of these oxidations with HOCl/Cl- or HOBr/Br- showed that the latter was more efficient, converting N-OH-2-FAA almost completely and less than or equal to 62% of N-OH-2-FBA to 2-NOF. The amounts of the ester (N- and o-BzO-2-FBA), which by itself did not contribute to 2-NOF formation or significant substrate regeneration, indicated that approximately 10% of 2-NOF originated from one-electron oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Biotransformation↗
PubMed2001

Subcellular localization of beta-glucosidase in rye, maize and wheat seedlings.

The subcellular compartmentation of beta-glucosidase was studied in rye, maize and wheat seedlings by immunocytochemical methods. For detection, we used a 10 nm gold-labeled secondary antibody, and results were observed using transmission electron microscopy. In all three species, beta-glucosidase was found in plastids, cytoplasm and cell walls. In rye, gold particles were seen on cell walls and cytoplasm in epidermal cells of the root tip and shoot, in bundle sheath cells of the shoot and in all cells, except the vascular bundle cells of the coleoptile. Gold labeling was also observed in plastids of the bundle sheath cells of rye shoot tips and in cortical cells of root tips. In wheat, gold labeling was observed on cell walls and cytoplasm of epidermal cells in the shoot base and coleoptile, and on cell walls and plastids in epidermal cells of the root tip. In maize, gold labeling was mainly found in plastids or proplastids in vascular bundle cells and bundle sheath cells of the shoot, in bundle sheath cells of the coleoptile and in epidermal cells of the root. Some gold particles were also found in cell walls and cytoplasm of stomatal guard cells of the shoot base and vascular bundle cells of the shoot tip and in the cell walls of bundle sheath cells of the shoot tip and root tip epidermal cells. Results are discussed in relation to the role of beta-glucosidase in hydroxamic acid release and overall defense mechanism of monocotyledons.

Journal Article↗
PubMed2006

Histone deacetylase inhibitors induce apoptosis with minimal viral reactivation in cells infected with Kaposi's sarcoma-associated herpesvirus.

Kaposi's sarcoma-associated herpesvirus (KSHV) latently infects tumor cells in patients with Kaposi's sarcoma and primary effusion lymphoma (PEL). The purpose of this study was to determine whether histone deacetylase inhibitors (HDAI) could induce apoptosis, with minimal viral replication, in cells latently infected with KSHV. Four HDAI (depsipeptide, suberoylanilide hydroxamic acid, MS-275, and trichostatin A) were studied in two PEL B cell lines (BCBL-1, BC-3). As expected, histone hyperacetylation was readily induced in all PEL cells exposed to HDAI. HDAI also triggered KSHV reactivation in a time- and dose-dependent manner. Flow cytometric and transmission electron microscopic studies, however, revealed that reactivation occurred in only a minor percentage (3-14%) of treated cells. Importantly, and in contrast to viral reactivation, HDAI induced apoptotic cell death in a dose-dependent manner in a large percentage (up to 90%) of KSHV-infected cells. In summary, all four HDAI tested induced histone hyperacetylation in all cells, KSHV reactivation in a minority of cells, and apoptotic cell death in a majority of cells latently infected with KSHV. These findings suggest that HDAI may be a therapeutic option for patients with KSHV-mediated diseases by rendering cells infected with KSHV susceptible to apoptosis.

Antiviral Agents↗
PubMed2006

Will broad-spectrum histone deacetylase inhibitors be superseded by more specific compounds?

Histone deacetylase (HDAC) inhibitors can induce differentiation, cell cycle and growth arrest or in certain cases apoptosis in cancer cells. In a remarkably short period of time, especially considering that their mechanism of action remains largely undefined, HDAC inhibitors have realized both success and failure as therapeutics for cancer in clinical trials. Notably, the pleiotropic HDAC inhibitors, suberoylanilide hydroxamic acid (SAHA) and depsipeptide, have shown efficacy in a wide range of cancers, in particular for cutaneous T-cell lymphoma (CTCL), and are progressing in phase II clinical studies. However, evidence is accumulating that specific HDAC enzymes are important with respect to clinical efficacy, calling the usefulness of the classical inhibitors into question. Class I enzymes are being heralded as the most clinically relevant, however, this is still controversial and much of the information is in the private domain. Nevertheless, the potential to alter the expression of a more focused, disease-related subset of genes and to limit adverse effects has prompted the development of isoform-specific HDAC inhibitors. Here, we consider the growing view that broad-spectrum HDAC inhibitors may be superseded by more specific compounds.

Animals↗
PubMed2004

Histone deacetylase inhibitors upregulate death receptor 5/TRAIL-R2 and sensitize apoptosis induced by TRAIL/APO2-L in human malignant tumor cells.

Death receptor 5 (DR5) is a receptor for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). TRAIL is a promising candidate for cancer therapeutics due to its ability to induce apoptosis selectively in cancer cells. Here, we report that histone deacetylase inhibitors (HDACIs) such as trichostatin A (TSA), sodium butyrate, and suberoylanilide hydroxamic acid (SAHA) upregulated DR5 expression in various human malignant tumor cells. An RNase protection assay demonstrated that HDACIs induced DR5 mRNA markedly but not that of other death receptor family members in Jurkat cells. HDACIs increased DR5 mRNA and protein in a dose- and time-dependent manner. We also show TSA increased DR5 promoter activity using a luciferase promoter assay. Furthermore, we demonstrated that HDACIs strongly sensitized exogenous soluble recombinant human TRAIL-induced apoptosis synergistically in Jurkat and HL-60 cells that were tolerant to TRAIL alone. The combined use of HDACIs and TRAIL in suboptimal concentrations induced Bid cleavage and activation of caspase-8, -10, -3, and -9. Human recombinant DR5/Fc chimera protein, zVAD-fmk pancaspase inhibitor, and caspase-8 and -10 inhibitors efficiently reduced apoptosis induced by cotreatment with HDACIs and TRAIL. Furthermore, TSA did not significantly induce DR5 protein and HDACIs did not enhance TRAIL-induced apoptosis in normal human peripheral blood mononuclear cells. These results suggest that this combined treatment with HDACIs and TRAIL is a promising strategy for new cancer therapeutics.

Apoptosis↗
PubMed2005

HDAC inhibitors enhance the apoptosis-inducing potential of TRAIL in breast carcinoma.

Histone deacetylase (HDAC) inhibitors induce differentiation and/or apoptosis in a variety of cell types by activating transcription of target genes. Activation of the death receptor (DR) pathway by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis preferentially in cancer cells. Here, we investigated the intracellular mechanisms by which HDAC inhibitors (suberoylanilide hydroxamic acid, m-carboxycinnamic acid bis-hydroxamide, MS-275 and trichostatin A) enhance the apoptosis-inducing potential of TRAIL in breast cancer cells in vitro. A synergism in apoptosis was observed in both TRAIL-sensitive and -resistant cells upon sequential treatments with HDAC inhibitors followed by TRAIL. HDAC inhibitors synergized with TRAIL by inducing DRs DR4/TRAIL-R1 and DR5/TRAIL-R2 through NFkappaB activation and some of the proapoptotic members of the Bcl-2 family, and engaging the mitochondrial pathway. The ability of HDAC inhibitors to sensitize TRAIL-resistant cells suggests that HDAC inhibitors may induce fundamental alterations in cell signaling pathways. Thus, the sequential treatments with HDAC inhibitors followed by TRAIL may be used as a new therapeutic approach for the treatment of human cancers.

Apoptosis↗
PubMed2003

Self-assembly of a molecular figure-of-eight strip.

A hexanuclear copper(ii) complex with a figure-of-eight strip topology is formed by metal-directed self-assembly of tritopic ligand L, bis-bidentate glycine hydroxamic acid and Cu(ii) ions in a 2:2:6 ratio.

Journal Article↗
PubMed2005

Nitric oxide release from the unimolecular decomposition of the superoxide radical anion adduct of cyclic nitrones in aqueous medium.

Nitrones such as 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO) and 5-ethoxycarbonyl-5-methyl-1-pyrroline N-oxide (EMPO) have become the spin-traps of choice for the detection of transient radical species in chemical and biological systems using electron paramagnetic resonance (EPR) spectroscopy. The mechanism of decomposition of the superoxide radical anion (O2(.-)) adducts of DMPO, DEPMPO and EMPO in aqueous solutions was investigated. Our findings suggest that nitric oxide (NO) was formed during the decomposition of the O2(.-) adduct as detected by EPR spin trapping using Fe(II)N-methyl-d-glucamine dithiocarbamate (MGD). Nitric oxide release was observed from the O2(.-) adduct formed from hypoxanthine-xanthine oxidase, PMA-activated human neutrophils, and DMSO solution of KO2. Nitric oxide formation was not observed from the independently generated hydroxyl radical adduct. Formation of nitric oxide was also indirectly detected as nitrite (NO2(.-)) utilizing the Griess assay. Nitrite concentration increases with increasing O2(.-) concentration at constant DMPO concentration, while NO2(.-) formation is suppressed at anaerobic conditions. Moreover, large excess of DMPO also inhibits NO2(.-) formation which can be attributed to the oxidation of DMPO to hydroxamic acid nitroxide (DMPO-X) by nitrogen dioxide (NO2), a precursor to NO2(.-). Product analysis was also conducted to further elucidate the mechanism of adduct decay using gas chromatography-mass spectrometry (GC-MS) technique.

Anions↗
PubMed1966

Acetyl transfer in arylamine metabolism.

1. N-Hydroxyacetamidoaryl compounds (hydroxamic acids) are metabolites of arylamides, and an enzyme that transfers the acetyl group from these derivatives to arylamines has been found in rat tissues. The reaction products were identified by thin-layer chromatography and a spectrophotometric method, with 4-amino-azobenzene as acetyl acceptor, was used to measure enzyme activity. 2. The acetyltransferase was in the soluble fraction of rat liver, required a thiol for maximum activity and had a pH optimum between 6.0 and 7.5. 3. The soluble fractions of various rat tissues showed decreasing activity in the following order: liver, adrenal, kidney, lung, spleen, testis, heart; brain was inactive. 4. With the exception of aniline and aniline derivatives all the arylamines tested were effective as acetyl acceptors but aromatic compounds with side-chain amino groups were inactive. 5. The N-hydroxyacetamido derivatives of 2-naphthylamine, 4-amino-biphenyl and 2-aminofluorene were active acetyl donors but N-hydroxyacetanilide showed only slight activity. Acetyl-CoA was not a donor. 6. Some properties of the enzyme are compared with those of other acetyltransferases.

Acetates↗
PubMed1969

Chemical and biological properties of mycobactins isolated from various mycobacteria.

Nine different strains of mycobacteria grown on media deficient in iron all produced mycobactins. Most strains produced one mycobactin in great preponderance. Mycobacteria from clearly distinct taxonomic groups gave mycobactins differing in the structure of their nuclei. One group of taxonomically related mycobacteria produced mycobactins having the same nucleus but with different distributions of side chains within the homologous mixtures. Simple methods are described for identifying mycobactins on a small scale; these may be of value in classifying mycobacteria. Structures are proposed for mycobactin A from Mycobacterium aurum, mycobactin R from M. terrae, mycobactin F, produced together with mycobactin H by M. fortuitum, and mycobactins M and N from M. marinum. The first three of these differ from known mycobactins in details of substitution and configuration of asymmetric centres in the nucleus. Mycobactins M and N are substantially different, having only small acyl groups (acetyl and propionyl respectively) at the hydroxamic acid centre of the mycobactic acid moiety. Both are homologous mixtures having long-chain saturated 3-hydroxy-2-methyl acid fragments in the cobactin moiety. All mycobactins so far isolated promote almost maximal growth of M. johnei at 30ng./ml. in liquid medium. The activity of some mycobactins extends to much lower concentrations, mycobactin S showing significant growth promotion at 0.3ng./ml. Mycobactin M or N in combination with mycobactins having a long side chain in the mycobactic acid moiety exerts a mutually antagonistic effect on the growth of M. johnei, the mixture giving less growth than either mycobactin separately. Mycobactin M also decreases the growth of M. kansasii and M. tuberculosis on liquid media. These antagonistic effects are probably caused by a lengthening of the lag phase.

Chromatography, Thin Layer↗
PubMed1970

Effects of sex hormones on enzymic esterification of 2-(N-hydroxy-acetamido) fluorene by rat liver cytosol.

1. Enzymic esterifications of 2-(N-hydroxyacetamido)fluorene and several other hydroxamic acids by liver cytosol were studied. Determination of 2-acetamido-3-methylthiofluorene was used for the assay. 2. With rat liver cytosol, requirement for ATP, Mg(2+) and SO(4) (2-) suggested formation of phosphate and sulphate esters of 2-(N-hydroxyacetamido)fluorene. 3. Rats showed sex and age differences in their activity. Liver from adult male rat was at least twice as active as liver from adult female rat. No such sex differences were found in mice, hamsters and guinea pigs. 4. Administration of testosterone (300mug/day) subcutaneously for 8 days increased the activity in the female rat by 100%, whereas diethylstilboestrol (100mug/day) had no effect. In the male rat diethylstilboestrol treatment decreased the activity by 60%, whereas testosterone pretreatment was without any effect. 5. Among various endocrine ablations such as adrenalectomy, castration, adrenalectomy-castration and hypophysectomy in the adult male rat, hypophysectomy was found to be the most effective in decreasing the activity of the liver to about 50% of control values. 6. Like 2-(N-hydroxyacetamido)fluorene, various other N-hydroxy derivatives of 2-acetamido-7-fluorofluorene, 2-acetamidophenanthrene, 4-acetamidobiphenyl and 4-acetamidostilbene were also shown to be esterified to different extents by rat liver cytosol.

Adenosine Triphosphate↗
PubMed1977

Phenol sulphotransferase and uridine diphosphate glucuronyltransferase from rat liver in vivo and vitro. 2,6-Dichloro-4-nitrophenol as selective inhibitor of sulphation.

Microsomal UDP-glucuronyltransferase and cytosolic sulphotransferase share many substrates, such as phenols and hydroxamic acids. In a search for a selective inhibitor of sulphation, several phenolic compounds were tested. 2,6-Dichloro-4-nitrophenol is introduced as a selective inhibitor of sulphation in vivo, having no effect on UDP-glucuronyltransferase activity. As substrate for both conjugating enzymes the phenolic drug harmol (7-hydroxy-1-methyl-9H-pyrido[3,4-b]indole) was used. In the rat in vivo 2,6-dichloro-4-nitrophenol caused almost complete inhibition of harmol sulphation after a single intraperitoneal injection (26mumol/kg) for 48h; the percentage of harmol sulphated decreased from 75% in controls to 5% in the treated rats. The percentage of harmol glucuronidated increased from 25 to 95%. Pentachlorophenol was equally effective but also highly toxic. Salicylamide had only a very-short-lasting inhibitory effect on sulphation. In vitro, 2,6-dichloro-4-nitrophenol inhibited sulphation of harmol by a rat liver postmitochondrial supernatant completely at 1mum, whereas even at 100mum it had no effect on glucuronidation of harmol. It is concluded that 2,6-dichloro-4-nitrophenol is a selective inhibitor of sulphation and, further, that its long duration of action makes it suitable for studies on the regulatory role of sulphation in some biological processes.

Animals↗
PubMed2007

An active site tyrosine residue is essential for amidohydrolase but not for esterase activity of a class 2 histone deacetylase-like bacterial enzyme.

HDACs (histone deacetylases) are considered to be among the most important enzymes that regulate gene expression in eukaryotic cells acting through deacetylation of epsilon-acetyl-lysine residues within the N-terminal tail of core histones. In addition, both eukaryotic HDACs as well as their bacterial counterparts were reported to also act on non-histone targets. However, we are still far from a comprehensive understanding of the biological activities of this ancient class of enzymes. In the present paper, we studied in more detail the esterase activity of HDACs, focussing on the HDAH (histone deacetylase-like amidohydrolase) from Bordetella/Alcaligenes strain FB188. This enzyme was classified as a class 2 HDAC based on sequence comparison as well as functional data. Using chromogenic and fluorogenic ester substrates we show that HDACs such as FB188 HDAH indeed have esterase activity that is comparable with those of known esterases. Similar results were obtained for human HDAC1, 3 and 8. Standard HDAC inhibitors were able to block both activities with similar IC(50) values. Interestingly, HDAC inhibitors such as suberoylanilide hydroxamic acid (SAHA) also showed inhibitory activity against porcine liver esterase and Pseudomonas fluorescens lipase. The esterase and the amidohydrolase activity of FB188 HDAH both appear to have the same substrate specificity concerning the acyl moiety. Interestingly, a Y312F mutation in the active site of HDAH obstructed amidohydrolase activity but significantly improved esterase activity, indicating subtle differences in the mechanism of both catalytic activities. Our results suggest that, in principle, HDACs may have other biological roles besides acting as protein deacetylases. Furthermore, data on HDAC inhibitors affecting known esterases indicate that these molecules, which are currently among the most promising drug candidates in cancer therapy, may have a broader target profile requiring further exploration.

Alcaligenes↗
PubMed1998

Phosphinic peptides, the first potent inhibitors of astacin, behave as extremely slow-binding inhibitors.

A series of phosphinic pseudo-peptides varying in length and composition have been designed as inhibitors of the crayfish zinc endopeptidase astacin, the prototype of the astacin family and of the metzincin superfamily of metalloproteinases. The most efficient phosphinic peptide, fluorenylmethyloxycarbonyl-Pro-Lys-PhePsi(PO2CH2)Ala-P ro-Leu-Val, binds to astacin with a Ki value of 42 nM, which is about three orders of magnitude below the corresponding values for previously used hydroxamic acid derivatives. However, the rate constants for association (kon = 96.8 M-1.s-1) and dissociation (koff = 4.1 x 10(-6) s-1) are evidence for the extremely slow binding behaviour of this compound. N-terminally or C-terminally truncated phosphinic analogues of this parent molecule are much less potent, indicating a critical role of the peptide size on the potency. In particular, omission of the N-terminal proline residue leads to a 40-fold increase in Ki which is mostly due to a 75-fold higher koff value. These findings are consistent with the previously solved crystal structure of astacin complexed with one of the phosphinic peptides, benzyloxycarbonyl-Pro-Lys-PhePsi(PO2CH2)Ala-Pro-O-methyl, Ki = 14 microM [Grams, Dive, Yiotakis, Yiallouros, Vassiliou, Zwilling, Bode and Stöcker (1996) Nature Struct. Biol. 3, 671-675]. This structure also reveals that the phosphinic group binds to the active site as a transition-state analogue. The extremely slow binding behaviour of the phosphinic peptides is discussed in the light of the conformational changes involving a unique 'tyrosine switch' in the structure of astacin upon inhibitor binding. The phosphinic peptides may provide a rational basis for the design of drugs directed towards other members of the astacin family which, like bone morphogenetic protein 1 (BMP1; i.e. the procollagen C-proteinase), have become targets of pharmacological research.

Binding Sites↗
PubMed2003

Regulation of microglial inflammatory response by histone deacetylase inhibitors.

The activation of microglial cells is involved in the pathogenesis of a variety of neurodegenerative diseases, stroke and traumatic brain injuries. Recent studies suggest that protein acetylation can affect the extent of inflammatory responses. Our aim was to elucidate whether histone deacetylase inhibitors, inducers of protein hyperacetylation, regulate the inflammatory response in neural models of inflammation in vitro and whether neurone-glia interactions affect this regulation. Interestingly, we observed that histone deacetylase inhibitors, such as trichostatin A (TSA) and suberoylanilide hydroxamic acid, strongly potentiated the lipopolysaccharide (LPS)-induced inflammatory response in murine N9 and rat primary microglial cells as well in neural co-cultures and hippocampal slice cultures. TSA clearly potentiated the LPS-induced expression of interleukin (IL)-6 and inducible nitric oxide synthase mRNAs, as well as the secretion of cytokines IL-6, tumour necrosis factor-alpha and macrophage inflammatory protein (MIP)-2, and nitric oxide (NO). Co-culture and slice culture experiments showed that the presence of astrocytes and neurones did not stimulate or prevent the pro-inflammatory potentiation induced by histone deacetylase inhibitor in microglial cells. The potentiation of cytokine and NO responses was blocked by the nuclear factor kappa B (NF-kappa B) inhibitors caffeic acid phenethyl ester and helenalin, demonstrating that the NF-kappa B signalling pathway is involved. The DNA-binding activity of the NF-kappa B complex was strongly increased by LPS treatment but not enhanced by TSA. This suggests that potentiation of the inflammatory response is not dependent on the level of cytoplasmic NF-kappa B activation or DNA-binding activity but that site of action may be at the level of transcriptional regulation. Our results suggest that environmental stresses, ageing, diet and diseases that regulate protein acetylation status may also affect the inflammatory response.

Animals↗
PubMed2001

Metalloproteases and inhibitors in arthritic diseases.

Controlling degradation of the extracellular matrix is crucial in arthritic diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA), as conventional treatments do not positively affect the structural properties of the articular tissues. Metalloproteases, a family of zinc-dependent enzymes, and more specifically the matrix metalloproteases (MMPs), play a premier role in joint articular tissue degeneration. Additional enzymes of the metalloprotease family, such as the membrane-type metalloproteases (MT-MMPs) and the adamalysins that include the ADAMs and the ADAMTS families, have also been found to be involved in these disease processes. At present, therapeutic intervention based on the inhibition of metalloproteases, and more particularly of the MMPs, is under intensive investigation, and several MMP inhibitors are in clinical development. Currently, MMP inhibitors are exemplified by several chemical classes: hydroxamic acids, carboxylic acids and thiols. One key issue in the clinical development of MMP inhibitors relates to whether broad-spectrum inhibitors active against a range of different enzymes or selective inhibitors targeted against a single enzyme or particular subset of the MMPs represents the optimal strategy. In this chapter, we address the different metalloprotease enzymes and sub-families and their implication in arthritic diseases. Furthermore, we assess physiological and chemical metalloprotease inhibitors, and for the latter, the current inhibitory classes of compounds being studied.

Arthritis, Rheumatoid↗