Assessment of Lipotoxic Endoplasmic Reticulum (ER) Stress in Nonalcoholic Steatohepatitis (NASH)

Nicotinate-curcumin improves NASH by inhibiting the AKR1B10/ACCα-mediated triglyceride synthesis

BACKGROUND

Nonalcoholic steatohepatitis (NASH) is a prevalent chronic liver condition. However, the potential therapeutic benefits and underlying mechanism of nicotinate-curcumin (NC) in the treatment of NASH remain uncertain.

METHODS

A rat model of NASH induced by a high-fat and high-fructose diet was treated with nicotinate-curcumin (NC, 20, 40 mg·kg- 1), curcumin (Cur, 40 mg·kg- 1) and metformin (Met, 50 mg·kg- 1) for a duration of 4 weeks. The interaction between NASH, Cur and Aldo-Keto reductase family 1 member B10 (AKR1B10) was filter and analyzed using network pharmacology. The interaction of Cur, NC and AKR1B10 was analyzed using molecular docking techniques, and the binding energy of Cur and NC with AKR1B10 was compared. HepG2 cells were induced by Ox-LDL (25 µg·ml- 1, 24 h) in high glucose medium. NC (20µM, 40µM), Cur (40µM) Met (150µM) and epalrestat (Epa, 75µM) were administered individually. The activities of ALT, AST, ALP and the levels of LDL, HDL, TG, TC and FFA in serum were quantified using a chemiluminescence assay. Based on the changes in the above indicators, score according to NAS standards. The activities of Acetyl-CoA and Malonyl-CoA were measured using an ELISA assay. And the expression and cellular localization of AKR1B10 and Acetyl-CoA carboxylase (ACCα) in HepG2 cells were detected by Western blotting and immunofluorescence.

RESULTS

The results of the animal experiments demonstrated that NASH rat model induced by a high-fat and high-fructose diet exhibited pronounced dysfunction in liver function and lipid metabolism. Additionally, there was a significant increase in serum levels of FFA and TG, as well as elevated expression of AKR1B10 and ACCα, and heightened activity of Acetyl-CoA and Malonyl-CoA in liver tissue. The administration of NC showed to enhance liver function in rats with NASH, leading to reductions in ALT, AST and ALP levels, and decrease in blood lipid and significant inhibition of FFA and TG synthesis in the liver. Network pharmacological analysis identified AKR1B10 and ACCα as potential targets for NASH treatment. Molecular docking studies revealed that both Cur and NC are capable of binding to AKR1B10, with NC exhibiting a stronger binding energy to AKR1B10. Western blot analysis demonstrated an upregulation in the expression of AKR1B10 and ACCα in the liver tissue of NASH rats, accompanied by elevated Acetyl-CoA and Malonyl-CoA activity, and increased levels of FFA and TG. The results of the HepG2 cell experiments induced by Ox-LDL suggest that NC significantly inhibited the expression and co-localization of AKR1B10 and ACCα, while also reduced levels of TC and LDL-C and increased level of HDL-C. These effects are accompanied by a decrease in the activities of ACCα and Malonyl-CoA, and levels of FFA and TG. Furthermore, the impact of NC appears to be more pronounced compared to Cur.

CONCLUSION

NC could effectively treat NASH and improve liver function and lipid metabolism disorder. The mechanism of NC is related to the inhibition of AKR1B10/ACCα pathway and FFA/TG synthesis of liver.

Research status and hotspots in the field of endoplasmic reticulum stress and liver disease: A bibliometric study

Recently, the study of endoplasmic reticulum stress (ERS) and liver disease has attracted much attention, but bibliometric analysis on this field is scarce. Therefore, to address this gap, we conducted a bibliometric analysis to explore the research status, hotspots, and trends in this field. We searched the Web of Science Core Collection database for publications on ERS and liver disease from 2007 to 2022. Bibliometric online analysis platform, VOSviewer, and CiteSpace were used to perform bibliometric analysis. Two thousand seven hundred fifty-one publications were retrieved form the Web of Science Core Collection database. The USA was the most productive and influential country. Seoul National University, International Journal of Molecular Sciences, and Kaufman RJ were the most productive institution, journal, and author. "Endoplasmic reticulum stress," "nonalcoholic fatty liver disease," "inflammation," "oxidative stress" and "insulin resistance" were the high-frequency keywords, "necrosis factor alpha" was the keywords with the strongest citation bursts, and "nonalcoholic fatty liver," "fibrosis" and "lipid droplet" were the keywords that were still bursting in 2022. The number of publications on ERS and liver disease has increased over the past years. The USA was the most productive and influential country. China has become the country with the largest number of annual publications, but it still needs to work on the quality. ERS and nonalcoholic fatty liver disease, especially the insulin resistance and lipotoxicity in hepatocytes may be the research hotspots and trends in this field of ERS and liver disease.

Derlin-1 promotes diet-induced non-alcoholic fatty liver disease via increasing RIPK3-mediated necroptosis

BACKGROUND & AIMS

Unrestricted endoplasmic reticulum (ER) stress and the continuous activation of ER associated protein degradation (ERAD) pathway might lead to the aggravation of non-alcoholic steatohepatitis (NASH). Derlin-1 has been considered to be an integral part of the ERAD pathway, which is involved in the regulation of the transport and excretion of protein degradation products within ER. However, the regulatory role and mechanism of Derlin-1 in NASH remains unclear.

METHODS

The expression of Derlin-1 was firstly detected in the liver of normal and NASH animal model and patient. Then, western diet (WD)-induced NASH mice were administrated with the lentivirus-mediated Derlin-1 knockdown or overexpression. Finally, RIPK3 knockout mice were used to explore the mechanism. The liver injury, hepatic steatosis, inflammation, and fibrosis as well as ER stress signal pathway were evaluated.

RESULTS

The levels of Derlin-1 were significantly elevated in the liver of WD-fed mice and NASH patients when compared to the control group. Furthermore, Derlin-1 knockdown attenuated WD-induced liver injury, lipid accumulation, inflammatory response, and fibrosis. Conversely, overexpression of Derlin-1 presented the completely opposite results. Mechanistically, Derlin-1 enhanced ER stress pathways and led to necroptosis, and RIPK3 knockout dramatically reduced Derlin-1 expression and reversed the progression of NASH aggravated by Derlin-1.

CONCLUSIONS

Notably, Derlin-1 is a critical modulator in NASH. It may accelerate the progression of NASH by regulating the activation of the ERAD pathway and further aggravating the ER stress, which might be involved in RIPK3-mediated necroptosis. Therefore, targeting Derlin-1 as a novel intervention point holds the potential to delay or even reverse NASH.

Hepatocytic Ballooning in Non-alcoholic Steatohepatitis: Bridging the Knowledge Gap and Charting Future Avenues

Non-alcoholic steatohepatitis (NASH) is emerging as a significant global health concern, characterized by hepatic lipid accumulation, inflammation, and hepatocellular injury. Hepatocytic ballooning, a histological feature of NASH, has gained prominence for its role in disease progression and potential as a therapeutic target. This review provides an overview of the current knowledge regarding hepatocytic ballooning in NASH, highlighting the key molecular and cellular mechanisms implicated in its development. We delve into the intricate interplay of metabolic dysregulation, oxidative stress, and lipid toxicity as drivers of hepatocytic ballooning, shedding light on the pathways responsible for its initiation and perpetuation. Furthermore, we explore the diagnostic challenges associated with hepatocytic ballooning and its significance as a prognostic indicator in NASH patients. While hepatocytic ballooning holds promise as a therapeutic target, this abstract discusses the various experimental and clinical approaches to ameliorate this histological hallmark. Potential interventions, including lifestyle modifications, pharmacological agents, and emerging therapies, are evaluated in terms of their efficacy and safety profiles. In conclusion, this review underscores the need to bridge the knowledge gap surrounding hepatocytic ballooning in NASH and emphasizes its importance in understanding disease pathogenesis and progression. By charting future research avenues and clinical strategies, we aspire to advance our comprehension of NASH and ultimately improve patient outcomes in this rapidly evolving field of hepatology.

Therapeutic effects of atorvastatin on doxorubicin-induced hepatotoxicity in rats via antioxidative damage, anti-inflammatory, and anti-lipotoxicity

Doxorubicin (DOX), is a high efficiency anthracycline antitumor drug. However, the clinical application of DOX is limited mainly by dose-related adverse drug reactions. Currently, the therapeutic effects of Atorvastatin (ATO) on DOX-induced hepatotoxicity were studied in vivo. The results indicated that DOX impaired hepatic function, as measured by an increased levels of liver weight index and serum concentrations of aspartate transaminase and alanine transaminase, as well as alteration of hepatic histology. In addition, DOX increased the serum levles of triglyceride (TG) and nonestesterified fatty acid. ATO prevented these changes. Mechanical analysis revealed that ATO restored the changes of malondialdehyde, reactive oxygen radical species, glutathione peroxidase and manganese superoxide dismutase. Additionally, ATO inhibited the increased expression levels of nuclear factor-kappa B and interleukin 1β, hence suppressing inflammation. Meanwhile, ATO inhibited cell apoptosis by dramatically decreasing the Bax/Bcl-2 ratio. In addition, ATO mitigated the lipidtoxicity by inhibiting the adipolysis of TG and accelerating hepatic lipid metabolism. Taken together, the results suggest ATO has therapeutic effect on DOX-induced hepatotoxicity via inhibition of oxidative damage, inflammatory and apoptosis. In addition, ATO attenuates DOX-induced hyperlipidemia via modulation of lipid metabolism.