Upregulation of 4-Hydroxynonenal Contributes to the Negative Effect of n-6 Polyunsaturated Fatty Acid on Alcohol-Induced Liver Injury and Hepatic Steatosis.

The present study aimed to investigate the effects of saturated fatty acids (SFA) and n-6 polyunsaturated fatty acids (PUFA) on alcoholic liver disease (ALD) and the underlying mechanisms. C57BL/6J male mice were randomly fed a corn oil or palm oil diet (rich in n-6 PUFA and SFA, respectively) with or without ethanol for four weeks (n = 10/group). A series of experiments in vitro with AML-12 hepatocyte were conducted to better elucidate the potential mechanisms underlying the phenomenon observed in animals. Compared with palm oil, corn oil aggravated alcohol-induced liver injury and hepatic steatosis, indicated by a histological analysis and significant elevations of plasma alanine aminotransferase and hepatic triacylglycerol (TG) level. Apoptosis-associated proteins in the ASK1-JNK pathway were significantly enhanced in the liver of mice from the corn oil + ethanol group than in the palm oil + ethanol group. The corn oil + ethanol diet also inhibited the activation of both AMPK and downstream protein acetyl-CoA carboxylase (ACC) and promoted the SREBP-1c expression, subsequently accelerating lipid synthesis. In addition, 4-hydroxynonenal (4-HNE) levels in plasma and liver were significantly upregulated in response to corn oil + ethanol feeding. Interestingly, the in vitro study showed that 4-HNE significantly attenuated cell viability, elevated the expression of cleaved-caspase 3 protein and TG level, and regulated key molecules in ASK1-JNK and AMPK pathways in a dose-dependent manner. In conclusion, the n-6 PUFA diet showed a negative effect on alcohol-induced liver injury and steatosis. It might be related to the upregulation of 4-HNE and subsequent changes of proteins, namely, ASK1, JNK, AMPK, ACC, and SREBP-1c.

N-Acetylcysteine alleviates high fat diet-induced hepatic steatosis and liver injury via regulating the intestinal microecology in mice.

N-Acetylcysteine (NAC), a well-accepted antioxidant, has been shown to protect against high fat diet (HFD)-induced obesity-associated non-alcoholic fatty liver disease (NAFLD) in mice. However, the underlying mechanism(s) of the beneficial role of NAC is still not fully understood. Our study aimed to evaluate the protective effect of NAC against NAFLD in terms of gut microbiota homeostasis. Thirty-two C57BL/6 mice were divided into four groups, including chow diet (CHOW), high-fat diet (HFD), CHOW + NAC (2 g L-1 in the drinking water), and HFD + NAC groups, and fed for 12 weeks. NAC supplementation significantly improved HFD-induced obesity, dyslipidemia, and liver dysfunction in mice. NAC also rescued HFD-caused disorder of the gut microbiota. Intriguingly, removing intestinal microorganisms by antibiotics (ABX) obviously abolished NAC supplementation-rescued hepatic steatosis and liver injury, indicating the involvement of the gut microbiota in the beneficial role of NAC. The profiles of 1145 expressed hepatic mRNAs were analyzed by whole transcriptome sequencing. Among those, 5 up-expressed mRNAs induced by a HFD, including Cidea, CD36, Acnat2, Mogat1, and GPAT3, were reversed by NAC treatment, which was further verified by a quantitative real-time polymerase chain reaction (qRT-PCR). Meanwhile, those 5 mRNAs exhibited a significant (negative or positive) association with bacterial phyla or genera, including phyla Firmicutes and Bacteroidetes and genera norank_f_Erysipelotrichaceae and Lachnoclostridium, by Spearman's correlation analysis. These results suggested that the homeostasis of the gut microbiota plays an important role in NAC-improved NAFLD by affecting the enterohepatic axis.

[Atractylenolide â improves acetaminophen-induced acute liver injury in mice by inhibiting MAPK/NF-κB signaling pathway].

This study explored the protective effect of atractylenolide Ⅰ(AO-Ⅰ) against acetaminophen(APAP)-induced acute liver injury(ALI) in mice and its underlying mechanism. C57 BL/6 J mice were randomly divided into a control group, an APAP group(500 mg·kg~(-1)), a low-dose combination group(500 mg·kg~(-1) APAP + 60 mg·kg~(-1) AO-Ⅰ), and a high-dose combination group(500 mg·kg~(-1) APAP + 120 mg·kg~(-1) AO-Ⅰ). ALI was induced by intraperitoneal injection of APAP(500 mg·kg~(-1)). AO-Ⅰ by intragastric administration was performed 2 hours before APAP treatment, and the control group received the same dose of solvent by intragastric administration or intraperitoneal injection. The protective effect of AO-Ⅰ against APAP-induced ALI was evaluated by detecting alanine aminotransferase(ALT) and aspartate aminotransferase(AST) levels in the plasma and H&E staining in liver tissues of mice. The malondialdehyde(MDA) and glutathione(GSH) content and catalase(CAT) activity in mouse liver tissues were detected to evaluate the effect of AO-Ⅰ on APAP-induced oxidative stress in the liver. The proteins in the liver p38 mitogen-activated protein kinase(p38 MAPK), c-jun N-terminal kinase(JNK), and nuclear factor kappa-B p65(NF-κB p65) signaling pathways were measured by Western blot, and the liver inflammatory cytokines interleukin-1ß(IL-1ß) and interleukin-6(IL-6) were detected by real-time PCR. Compared with the APAP group, the combination groups showed reduced APAP-induced ALT level and liver MDA content, potentiated liver CAT activity, and elevated GSH content. Mechanistically, AO-Ⅰ treatment significantly inhibited APAP-up-regulated MAPK phosphorylation and NF-κB p65, and significantly reduced the transcriptional activities of IL-1ß and IL-6, downstream targets of NF-κB p65. AO-Ⅰ can improve APAP-induced ALI and the underlying mechanism is related to the inhibition of the MAPK/NF-κB p65 signaling pathway in APAP-challenged mice.

Characterization of the anti-Staphylococcus aureus fraction from Penthorum chinense Pursh stems.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) causes serious infections in hospitals. Penthorum chinense Pursh (PCP), employed by the Miao ethnic minority in China, presents antibacterial activities. In this study, the anti-Staphylococcus aureus activities in the pinocembrin-7-O residue-rich fraction from PCP (PGF) were evaluated and characterized. METHODS: The PGF was prepared with 70% ethanol reflux extraction followed by fractional extraction and column chromatography. Pinocembrin-7-O residue components were identified with electrospray ionization mass spectrometry (ESI-MS). Anti-S. aureus activities of the fraction and the main components were evaluated in vitro with serially diluted microbroth assays. Cytotoxicity was evaluated with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) chromogenic assays using the NCTC 1469 cell line. RESULTS: This study indicated that the PGF and three components (S1, S2, and S3) presented anti-S. aureus activities, including against clinically isolated MRSA strains. The molecular masses of S1, S2, and S3 were identical to those of pinocembrin-7-O-[4″,6″-hexahydroxydiphenoyl (HHDP)]-ß-D-glucose, pinocembrin-7-O-[3″-O-galloyl-4″,6″-(s)-HHDP]-ß-D-glucose, and Thonningianin A, respectively. The PGF, S1, S2, and S3 all presented an identical minimum inhibitory concentration (MIC) against S. aureus ATCC 25923 and ATCC 43300, which was 62.5 µg/mL. The minimum bactericidal concentrations (MBCs) of the PGF and S3 against ATCC 25923 were 125 and 250 µg/mL, and the MBCs of the PGF, S2, and S3 against ATCC 43300 were 250, 500, and 250 µg/mL, respectively. A time-kill assay consistently indicated that none of the bacterial clones of ATCC 25923 and ATCC 43300 could survive under 2× and 4× MIC PGF treatment for 24 h, respectively. In contrast, 104 CFU (colony-forming units) of ATCC 25923 and ATCC 43300 were killed by 8× and 4× MIC S3 within 24 h, respectively. Additionally, 1×, 2×, and 4× MIC the PGF presented similar postantibiotic effects (PAEs) on the strain ATCC 25923. However, the PAE of the PGF on the strain ATCC 43300 was concentration dependent (1× < 2× < 4× MIC). Finally, the PGF (200 µg/mL) and S3 (60 µg/mL) showed no cytotoxicity against human hepatoma cells. CONCLUSIONS: The PGF and S3 from PCP present potential for the treatment of S. aureus and MRSA infections. The components S1 and S2 present inhibition activities against S. aureus.