25 research outputs found

    Inhibition of gastric H,K-ATPase activity and gastric epithelial cell IL-8 secretion by the pyrrolizine derivative ML 3000

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    BACKGROUND: ML 3000 ([2,2-dimethyl-6-(4-chlorophenyl)-7-phenyl-2,3-dihydro-1H-pyrrolizine-5-yl]-acetic acid) is an inhibitor of both cyclooxygenase and 5-lipoxygenase in vitro, and shows promise as a novel non-steroidal anti-inflammatory drug (NSAID). Unlike conventional NSAIDs which are associated with gastric ulcerogenic effects, ML 3000 causes little or no damage to the gastric mucosa, even though it significantly depresses gastric prostaglandin synthesis. METHODS: As part of an effort to clarify mechanisms underlying the gastric sparing properties of ML 3000, we studied the effects of ML 3000 on H,K-ATPase activity in vitro, on acid accumulation in isolated gastric parietal cells, and on IL-8 secretion by gastric epithelial cells in culture. RESULTS: SCH28080-sensitive H,K-ATPase activity in highly-purified pig gastric microsomes was dose-dependently inhibited by ML 3000 (IC(50) = 16.4 Ī¼M). Inhibition was reversible, and insensitive to ML 3000 acidification in the pH range 2.0ā€“8.0. In rabbit gastric parietal cells, ML 3000 dose-dependently inhibited histamine-stimulated acid accumulation (IC(50) = 40 Ī¼M) and forskolin-stimulated acid accumulation (IC(50) = 45 Ī¼M). Lastly, in human gastric adenocarcinoma (AGS) cells, ML 3000 dose-dependently inhibited both baseline and IL-1Ī²-stimulated (20 ng/ml) IL-8 secretion with IC(50)s of 0.46 Ī¼M and 1.1 Ī¼M respectively. CONCLUSION: The data indicate that ML 3000 affects acid-secretory mechanisms downstream of cAMP mobilization induced by histamine H(2) receptor activation, that it directly inhibits H,K-ATPase specific activity, and that baseline gastric epithelial cell IL-8 secretory inhibition may be mediated by ML 3000 inhibition of 5-lipoxygenase activity. We conclude that these gastric function inhibitory data may underlie the gastric sparing properties of ML 3000

    The effects of tumour necrosis factor-alpha on bone cells involved in periodontal alveolar bone loss; osteoclasts, osteoblasts and osteocytes

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    Periodontitis is the most common bone loss pathology in adults and if left untreated is responsible for premature tooth loss. Cytokines, such as tumour necrosis factor-Ī± (TNFĪ±), involved in the chronic inflammatory response within the periodontal gingiva, significantly influence the normal bone remodelling processes. In this review, the effects of TNFĪ± on bone metabolism in periodontitis are evaluated in relation to its direct and indirect actions on bone cells including osteoclasts, osteoblasts and osteocytes. Evidence published to date suggests a potent catabolic role for TNFĪ± through the stimulation of osteoclastic bone resorption as well as the suppression of osteoblastic bone formation and osteocytic survival. However, the extent and timing of TNFĪ± exposure in vitro and in vivo greatly influences its effect on skeletal cells, with contradictory anabolic activity observed with TNFĪ± in a number of studies. None the less, it is evident that managing the chronic inflammatory response in addition to the deregulated bone metabolism is required to improve periodontal and inflammatory bone loss treatmentsā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬ā€¬.K. Algate, D.R. Haynes, P.M. Bartold, T.N. Crotti, M.D. Cantle

    Class I and II histone deacetylase expression in human chronic periodontitis gingival tissue

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    Histone deacetylase inhibitors (HDACi) are being considered to treat chronic inflammatory diseases at low doses. Currently HDACi that are more specific are being developed to target particular HDACs; therefore, this study aimed to determine levels and distribution of class I and II HDAC in human gingival samples obtained from patients with chronic periodontitis.Gingival biopsies were obtained from patients with and without (mild inflammation, no bone loss) periodontitis. Total RNA was isolated for real-time quantitative polymerase chain reaction to determine expression of HDACs 1-10. Immunohistochemistry was used to determine protein distribution of HDACs 1, 5, 8 and 9. Factor VIII, CD3 and tartrate resistant acid phosphatase (TRAP) were detected in serial sections to identify blood vessels, lymphocytes, pre-osteoclasts and osteoclasts cells respectively. Tumour necrosis factor Ī± (TNF-Ī±) expression was also assessed.mRNA for HDAC 1, 5, 8 and 9 were significantly upregulated inĀ chronic periodontitis gingival tissues compared to non-periodontitis samplesĀ (pĀ <Ā 0.05). Significantly higher HDAC 1 protein expression was observed in chronic periodontitis samples (pĀ <Ā 0.05), and was associated withĀ CD3, TRAP and TNF-Ī±-positive cells. HDAC 1, 5, 8 and 9 were expressed strongly by the factor VIII-positive microvasculature in the chronic periodontitis gingival tissues.HDAC 1, 5, 8 and 9 expression was higher in gingival tissues from patients with chronic periodontitis compared to non-periodontitis samples. Results suggest that these HDACs could therefore be targeted with specific acting HDACi.M. D. Cantley, A. Dharmapatni, K. Algate, T. N. Crotti, P. M. Bartold, D. R. Hayne

    Semaphorin-3a, neuropilin-1 and plexin-A1 in prosthetic-particle induced bone loss

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    Abstract not availableS. Saad, A.A.S.S.K. Dharmapatni, T.N. Crotti, M.D. Cantley, K. Algate, D.M. Findlay, G.J. Atkins, D.R. Hayne

    Histone deacetylases 1 and 2 inhibition suppresses cytokine production and osteoclast bone resorption in vitro

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    First published: 21 June 2019The regulation of epigenetic factors is an emerging therapeutic target of immune function in a variety of osteolytic pathologies. Histone deacetylases (HDAC) modify core histone proteins and transcriptional processes, in addition to nonhistone protein activity. The activated immune response in rheumatoid arthritis, periodontitis, and prosthetic implant particle release stimulates the catabolic activity of osteoclasts. In this study, we investigated the effects of novel therapeutic agents targeting HDAC isozymes (HDAC 1, 2, and 5), previously shown to be upregulated in inflammatory bone disorders, in cytokine-stimulated human monocytes and osteoclasts in vitro. Inhibiting HDAC 1 and 2 significantly reduced gene expression of IL-1Ī², TNF, MCP-1, and MIP-1Ī± in TNF-stimulated monocytes, while suppressing secretions of IL-1Ī², IL-10, INF-Ī³, and MCP-1 (Pā€‰<ā€‰.05). Osteoclast formation and bone resorption were also significantly diminished with HDAC 1 and 2 inhibition, through reduced NFATc1 expression and osteoclast specific target genes, TRAF6, CTR, TRAP, and Cathepsin K (Pā€‰<ā€‰.05). Similar trends were observed when inhibiting HDAC 1 and to a lesser extent, HDAC 2, in isolation. However, their combined inhibition had the greatest anti-inflammatory and antiosteoclastic effects. Targeting HDAC 5 had minimal effects on these processes investigated in this study, whereas a broad acting HDACi, 1179.4b, had widespread suppressive outcomes. This study demonstrates that targeting HDACs is a potent and effective way of regulating the inflammatory and catabolic processes in human monocytes and osteoclasts. It also demonstrates the importance of targeting individual HDACs with an overall aim to improve efficiency and reduce any potential off target effects.Kent Algate, David Haynes, Tracy Fitzsimmons, Ornella Romeo, Florence Wagner, Edward Holson, Robert Reid, David Fairlie, Peter Bartold, Melissa Cantle
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