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Background: Histone deacetylase 6 (HDAC6) has been considered as an important regulator in the development of inflammatory diseases. However, the mechanism of HDAC6 in regulating inflammatory responses has not been fully determined. In the present study, we aim to investigate the role and mechanisms of HDAC6 in regulating inflammation in lipopolysaccharide (LPS)-activated macrophages., Methods: Flow cytometry was used to determine a suitable treatment dosage of ACY-1215 on lipopolysaccharide (LPS)-activated macrophages for the present study. The RAW264.7 macrophages were divided into normal, LPS-treated, and ACY-1215 treated groups, respectively. For the ACY-1215 group, ACY-1215 (10 μM) was added to the medium 2 h prior to treatment with LPS (1 μg/ml) for 24 h. In this study, ROS, inflammatory cytokines, the ultrastructure of mitochondria, mitochondrial membrane potential, RNA and protein expression assay were detected respectively. Subsequently, the effect of HDAC6 knockdown on inflammatory response in LPS-activated RAW264.7 macrophages was also detected., Results: Inhibition of HDAC6 inhibited the overproduction of ROS and suppressed the expression of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6 in LPS-activated RAW264.7 cells. Pretreatment with ACY-1215 could normalize the ultrastructure of mitochondria and mitochondrial membrane potential in LPS-activated macrophages. Moreover, the protein expression of TLR4, Nrf2, HO-1 and the activation of MAPK and NF-κB signaling pathways were normalized by the inhibition of HDAC6., Conclusions: Inhibition of HDAC6 exhibited protective role against LPS-induced inflammation in RAW264.7 cells by regulating oxidative stress and suppressing the activation of TLR4- MAPK/NF-κB signaling pathway., (Copyright © 2019 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Neuroinflammation involves in the progression of many central nervous system diseases. Several studies have shown that histone deacetylase (HDAC) inhibitors modulated inflammatory responses in lipopolysaccharide (LPS) stimulated microglia. While, the mechanism is still unclear. The aim of present study was to investigate the effect of HDAC2 inhibitor CAY10683 on inflammatory responses and TLR4/NF-κB signaling pathways in LPS activated BV2 microglial cells and LPS induced mice neuroinflammation. The effect of CAY10683 on cell viability of BV2 microglial cells was detected by CCK-8 assay. The expressions of inflammatory cytokines were analyzed by western blotting and RT-PCR respectively. The TLR4 protein expression was measured by western blotting, immunofluorescence, immunohistochemistry respectively. The protein expressions of MYD88, phospho-NF-κB p65, NF-κB-p65, acetyl-H3 (AH3), H3, and HDAC2 were analyzed by western blotting. We found that CAY10683 could inhibit expression levels of inflammatory cytokine TNF-α and IL-1β in LPS activated BV2 microglial cells and LPS induced mice neuroinflammation. It could induce TLR4, MYD88, phospho-NF-κB p65, and HDAC2 expressions. Moreover, CAY10683 increased the acetylation of histones H3 in LPS activated BV2 microglial cells and LPS induced mice neuroinflammation. Taken together, our findings suggested that HDAC2 inhibitor CAY10683 could suppress neuroinflammatory responses and TLR4/NF-κB signaling pathways by acetylation after LPS stimulation.

The purpose of this study was to investigate the protective mechanism of HDAC2 inhibitor CAY10683 on intestinal mucosal barrier in acute liver failure (ALF). In order to establish ALF-induced intestinal epithelial barrier disruption models, D-galactosamine/LPS and LPS were, respectively, used with rats and NCM460 cell and then administrated with CAY10683. Transepithelial electrical resistance (TEER) was measured to detect the permeability of cells. Real-time PCR and Western blotting were employed to detect the key mRNA and protein levels. The intestinal epithelial tissue pathology was detected. After interfering with CAY10683, the mRNA and protein levels of TLR4, MyD88, TRIF, and TRAF6 were decreased compared with model group ( P < 0.05), whereas the levels of ZO-1 and occluding were elevated ( P < 0.05). The permeability was elevated in CAY10683-interfered groups, when compared with model group ( P < 0.05). And the degree of intestinal epithelial tissue pathological damage in CAY10683 group was significantly reduced. Moreover, CAY10683 significantly decreased the TLR4 staining in animal tissue. The HDAC2 inhibitor CAY10683 could promote the damage of intestinal mucosal barrier in ALF through inhibiting LPS/TLR4/MyD88 pathway.

In this study, we induced an acute-on-chronic liver failure (ACLF) model by human serum albumin (HSA), D-galactosamine (D-Gal) and lipopolysaccharide (LPS) in rats. Anti-TNF-α polyclonal antibody (as TNF-α inhibitor) and pyrrolidine dithiocarbamate (PDTC, a NF-κB inhibitor) were used to treat the liver failure animals, respectively. The results showed that TNF-α inhibition was beneficial, but NF-κB inhibition failed to protect the rats in ACLF. However, HMGB1 levels, cytokine production and activation of TLR4-NF-κB signaling pathway were all suppressed by both TNF-α and NF-κB inhibition. In order to verify the effect of PDTC on inflammatory response, we further explored its effect in vitro. Anti-inflammatory activity of PDTC was proved in U937 cell line. To conclude, both inhibitions of TNF-α and NF-κB are able to suppress the activation of TLR4 and NF-κB signaling pathway. However, NF-κB inhibition with PDTC failed to protect the rats in ACLF induced by D-Gal and LPS.

Background and Objectives: Previous studies have shown that betaine prevents alcohol-induced liver injury and improves liver function. The purpose of this study was to investigate the hepatoprotective effects of betaine on nonalcoholic fatty liver disease (NAFLD) and to observe changes of HMGB1/TLR4 signaling., Methods: Thirty rats were randomly divided into control, model, and betaine groups. The rats in the model and betaine groups were fed a high-fat diet for 12 weeks to induce an animal model of NAFLD. The rats in the betaine group were then intragastrically administered betaine solution at a dose of 400 mg/kg per day for four weeks. Liver histology was examined. Serum levels of ALT, AST, TC, TG, HDL-C, LDL-C, FFA, HMGB1, NF-κB, TLR4, and tHcy were determined and intrahepatic TC, TG, and Hcy levels were assayed. mRNA expression and protein levels of HMGB1, NF-κB, and TLR4 in liver tissue were also determined., Results: Compared with the control group, rats in the model group developed severe liver injury, accompanied by significant increases in serum levels of ALT, AST, TC, TG, LDL-C, FFA, HMGB1, NF-κB, and TLR4, intrahepatic TC, TG, and Hcy content, histological scores for steatosis, inflammation, and necrosis, and mRNA expression and protein levels of HMGB1, NF-κB, and TLR4, and a significant decrease in serum HDL-C (P < 0.05). Compared with the model group, all these indicators were significantly improved by administration of betaine (P < 0.05)., Conclusions: Betaine effectively protects against high-fat-diet-induced NAFLD and improves liver function; the mechanism is probably related to inhibition of HMGB1/TLR4 signaling pathways.

Aim: To test whether ethanol feeding could induce Toll-like receptor 4 (TLR4) responses, assess the hepatoprotective effect of betaine and its inhibitive effect on TLR4 in animal models of alcoholic liver injury., Methods: Forty-eight female Sprague-Dawley rats were randomly divided into four groups as control, model, low and high dose betaine groups. Except control group, all rats were fed with high fat-containing diet plus ethanol and fish oil gavages for 8 wk. Betaine was administered intragastrically after exposure of ethanol for 4 wk. The changes of liver histology were examined. The expression of TLR4 mRNA and protein was detected by RT-PCR and Western blot, respectively. The serum aminotransferase activity [alanine transarninase (ALT), aspartate aminotransferase (AST)], serum endotoxin, and liver inflammatory factors [tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-18 (IL-18)] were also assayed., Results: Compared with control group, rats of model group developed marked liver injury, accompanied by an increase of ALT (159.41 +/- 7.74 U/L vs 59.47 +/- 2.34 U/L, P < 0.0001), AST (248.25 +/- 1.40 U/L vs 116.89 +/- 3.48 U/L, P < 0.0001), endotoxin (135.37 +/- 30.17 ng/L vs 44.15 +/- 7.54 ng/L, P < 0.0001), TNF-alpha (20.81 +/- 8.58 pg/mL vs 9.34 +/- 2.57 pg/mL, P = 0.0003), IFN-gamma (30.18 +/- 7.60 pg/mL vs 16.86 +/- 9.49 pg/mL, P = 0.0039) and IL-18 (40.99 +/- 8.25 pg/mL vs 19.73 +/- 9.31 pg/mL, P = 0.0001). At the same time, the expression of TLR4 mRNA and protein was markedly induced in the liver after chronic ethanol consumption (1.45 +/- 0.07 vs 0.44 +/- 0.04, P < 0.0001; 1.83 +/- 0.13 vs 0.56 +/- 0.08, P < 0.0001). Compared with model group, betaine feeding resulted in significant decreases of ALT (64.93 +/- 6.06 U/L vs 159.41 +/- 7.74 U/L, P < 0.0001), AST (188.73 +/- 1.11 U/L vs 248.25 +/- 1.40 U/L, P < 0.0001), endotoxin (61.80 +/- 12.56 ng/L vs 135.37 +/- 30.17 ng/L, P < 0.0001), TNF-alpha (9.79 +/- 1.32 pg/mL vs 20.81 +/- 8.58 pg/mL, P = 0.0003), IFN-gamma (18.02 +/- 5.96 pg/mL vs 30.18 +/- 7.60 pg/mL, P = 0.0008) and IL-18 (18.23 +/- 7.01 pg/mL vs 40.99 +/- 8.25 pg/mL, P < 0.0001). Betaine also improved liver steatosis. The expression levels of TLR4 mRNA or protein in liver tissues were significantly lowered (0.62 +/- 0.04 vs 1.45 +/- 0.07, P < 0.0001; and 0.65 +/- 0.06 vs 1.83 +/- 0.13, P < 0.0001). There was a statistical difference of TLR4 mRNA and protein expression between high- and low-dose betaine groups (0.62 +/- 0.04 vs 0.73 +/- 0.05, P < 0.0001, and 0.65 +/- 0.06 vs 0.81 +/- 0.09, P < 0.0001)., Conclusion: Betaine can prevent the alcohol-induced liver injury effectively and improve the liver function. The expression of TLR4 increases significantly in ethanol-fed rats and betaine administration can inhibit TLR4 expression.