Publications (2)23.33 Total impact
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Article: Inhibition of heat shock protein (molecular weight 90 kDa) attenuates proinflammatory cytokines and prevents lipopolysaccharide-induced liver injury in mice.
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ABSTRACT: Endotoxin-mediated proinflammatory cytokines play a significant role in the pathogenesis of acute and chronic liver diseases. Heat shock protein 90 (molecular weight, 90 kDa) (hsp90) functions as an important chaperone of lipopolysaccharide (LPS) signaling and is required for the production of proinflammatory cytokines. We hypothesized that inhibition of hsp90 would prevent LPS-induced liver injury by decreasing proinflammatory cytokines. C57BL/6 mice were injected intraperitoneally with an hsp90 inhibitor, 17-dimethylamino-ethylamino-17-demethoxygeldanamycin (17-DMAG), and LPS. Parameters of liver injury, proinflammatory cytokines, and associated mechanisms were studied by in vivo and in vitro experiments. Inhibition of hsp90 by 17-DMAG prevented LPS-induced increases in serum alanine aminotransferase activity and significantly reduced serum tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6) protein as well as messenger RNA (mRNA) in liver. Enhanced DNA-binding activity of heat shock transcription factor 1 (HSF1) and induction of target gene heat shock protein 70 (molecular weight, 70 kDa) confirmed hsp90 inhibition in liver. 17-DMAG treatment decreased cluster of differentiation 14 mRNA and LPS-induced nuclear factor kappa light-chain enhancer of activated B cells (NFκB) DNA binding without affecting Toll-like receptor 4 mRNA in liver. Mechanistic studies revealed that 17-DMAG-mediated inhibition of TNFα showed no effect on LPS-induced NFκB promoter-driven reporter activity, but significantly decreased TNFα promoter-driven reporter activity. Chromatin immunoprecipitation assays showed that 17-DMAG enhanced HSF1 binding to the TNFα promoter, but not the IL-6 promoter, suggesting HSF1 mediated direct inhibition of TNFα, but not IL-6. We show that HSF1 indirectly regulates IL-6 by the induction of another transcription factor, activating transcription factor 3. Inhibition of HSF1, using small interfering RNA, prevented 17-DMAG-mediated down-regulation of NFκB-binding activity, TNFα, and IL-6 induction, supporting a repressive role for HSF1 on proinflammatory cytokine genes during hsp90 inhibition. CONCLUSION: Hsp90 inhibition in vivo reduces proinflammatory cytokines and prevents LPS-induced liver injury likely through repressive action of HSF1. Our results suggest a novel application for 17-DMAG in alleviating LPS-induced liver injury.Hepatology 11/2011; 55(5):1585-95. · 11.66 Impact Factor -
Article: An essential role for monocyte chemoattractant protein-1 in alcoholic liver injury: regulation of proinflammatory cytokines and hepatic steatosis in mice.
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ABSTRACT: The importance of chemokines in alcoholic liver injury has been implicated. The role of the chemokine, monocyte chemoattractant protein-1 (MCP-1), elevated in patients with alcoholic liver disease is not yet understood. Here, we evaluated the pathophysiological significance of MCP-1 and its receptor, chemokine (C-C motif) receptor 2 (CCR2), in alcoholic liver injury. The Leiber-DeCarli diet containing alcohol or isocaloric control diets were fed to wild-type (WT) and MCP-1-deficient knockout (KO) mice for 6 weeks. In vivo and in vitro assays were performed to study the role of MCP-1 in alcoholic liver injury. MCP-1 was increased in Kupffer cells (KCs) as well as hepatocytes of alcohol-fed mice. Alcohol feeding increased serum alanine aminotransferase in WT and CCR2KO, but not MCP-1KO, mice. Alcohol-induced liver steatosis and triglyceride were attenuated in alcohol-fed MCP-1KO, but high in CCR2KO mice, compared to WT, whereas serum endotoxin was high in alcohol-fed WT and MCP-1KO mice. Expression of liver proinflammatory cytokines tumor necrosis factor alpha, interleukin (IL)-1β, IL-6, KC/IL-8, intercellular adhesion molecule 1, and cluster of differentiation 68 was induced in alcohol-fed WT, but inhibited in MCP-1KO, mice independent of nuclear factor kappa light-chain enhancer of activated B cell activation in KCs. Oxidative stress, but not cytochrome P450 2E1, was prevented in chronic alcohol-fed MCP-1KO mice, compared to WT. Increased expression of peroxisome proliferator-activated receptor (PPAR)α and PPARγ was accompanied by nuclear translocation, DNA binding, and induction of fatty acid metabolism genes acyl coenzyme A oxidase and carnitine palmitoyltransferase 1A in livers of alcohol-fed MCP-1KO mice, compared to WT controls. In vitro assays uncovered an inhibitory effect of recombinant MCP-1 on PPARα messenger RNA and peroxisome proliferator response element binding in hepatocytes independent of CCR2. Conclusion: Deficiency of MCP-1 protects mice against alcoholic liver injury, independent of CCR2, by inhibition of proinflammatory cytokines and induction of genes related to fatty acid oxidation, linking chemokines to hepatic lipid metabolism.Hepatology 08/2011; 54(6):2185-97. · 11.66 Impact Factor
