Caffeine can alleviate non-alcoholic fatty liver disease by augmenting LDLR expression via targeting EGFR

Resveratrol improved atherosclerosis by increasing LDLR levels via the EGFR-ERK1/2 signaling pathway

BACKGROUND AND AIMS

Atherosclerosis (AS) is a complex and chronic vascular disease and elevated low-density lipoprotein cholesterol (LDL-C) level is one of its primary causative factors. As a key surface receptor, low-density lipoprotein receptor (LDLR) plays an essential role in LDL-C clearance. Resveratrol (RSV) has emerged as a promising compound for investigating potential therapeutic targets for AS due to its ability to lower cholesterol, reduce endothelial anti-inflammatory and suppress vascular smooth muscle cell proliferation. This study explored the effects of RSV on AS through upregulating LDLR and analyzed the mechanism through a combination of in vivo and vitro experiments.

METHODS

HepG2 cells were exposed to varying concentrations of RSV. The effects of RSV on LDLR expression and cholesterol uptake were analyzed by western blot, RT-qPCR and DiI-LDL uptake assay. In vivo, C57BL/6J ApoE-/- mice were used and the experimental groups were treated with RSV, Lovastatin and Gefitinib. Plaque formation in the arteries and aortic roots was assessed by Oil Red O staining and plaque stability was evaluated using Hematoxylin-Eosin (H&E) and Elastic Van Gieson (EVG) staining. Western blot, RT-qPCR and immunohistochemical staining were employed to analyze the expression of LDLR in the livers of mice.

RESULTS

RSV significantly enhanced the stability of LDLR mRNA and promoted LDLR protein expression. The inhibition experiments of EGFR signaling pathway (Cetuximab and Gefitinib) demonstrated that the efficacy of RSV was markedly weakened when this signaling pathway was inhibited. It indicated that RSV modulated LDLR gene expression by activating EGFR-ERK1/2 pathway. In ApoE-/- mice, RSV notably reduced arterial plaque formation, improved plaque stability and increased hepatic LDLR expression.

CONCLUSION

This study elucidated the mechanism by which RSV upregulates LDLR gene expression through activating EGFR-ERK1/2 signaling pathway. In vivo experiments demonstrated its efficacy in reducing arterial plaque formation and stabilizing existing plaques. These results further indicated that RSV held potential therapeutic value for ameliorating atherosclerosis and cardiovascular diseases. Collectively, these findings provided novel theoretical support for RSV's potential role in cardiovascular therapy.

Transcriptomic analysis reveals the mechanisms underlying the differential effects of caffeine, theophylline, and theobromine in regulating hepatic fat accumulation

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease, characterized by excessive fat accumulation in the liver. Caffeine, theophylline, and theobromine are the primary naturally occurring methylxanthines found in various foods and beverages such as coffee, tea, and chocolate. They exhibit diverse pharmacological effects. Although caffeine can inhibit hepatic fat accumulation in mice, the effects and regulatory mechanisms of theophylline and theobromine remain unclear. In this study, we observed that theophylline significantly reduced body weight and triglyceride levels and attenuated hepatic fat accumulation in mice fed a high-fat diet. Conversely, theobromine did not exhibit these effects. Transcriptomic results showed that caffeine and theophylline significantly activated the TNF signaling pathway in C2C12 myoblasts, induced p38MAPK expression and increased Il1b and Il6 secretion, but did not elevate Tnfa and Mcp1 expression. Notably, theobromine neither activated the TNF pathway nor significantly induced p38MAPK expression and Il1b and Il6 secretion. In conclusion, the differences in the regulating NAFLD activity of caffeine, theophylline, and theobromine-three structurally similar compounds used as food ingredients, may be attributed to their distinct regulation of the TNF signaling pathway.

Caffeine ameliorates metabolic-associated steatohepatitis by rescuing hepatic Dusp9

Caffeine (CAFF) is abundant in black coffee. As one of the most widely consumed beverages globally, coffee has been the focus of increasing clinical and basic research, particularly regarding its benefits in alleviating metabolic dysfunction-associated steatotic liver disease (MASLD). However, the therapeutic effects of CAFF on metabolic-associated steatohepatitis (MASH) and the underlying mechanisms remain unclear. In this study, we demonstrated that CAFF potently reduced hepatic steatosis, inflammation, and early-stage liver fibrosis in MASH mice induced by prolonged (36 weeks) high-fat high-carbohydrate (HFHC) diets and high-fat diets combined with carbon tetrachloride (CCl4) injections. By using multiple target-identifying strategies, including surface plasmon resonance (SPR), cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) assay, we identified dual-specificity phosphatase 9 (Dusp9) as a key therapeutic target, which was diminished by HFHC but restored with CAFF treatment. Dusp9 knockdown in vivo and in vitro exacerbated glycolipid metabolism disorders and stunningly counteracted the systemic therapeutic effects of CAFF in the MASH models. In addition, CAFF inactivated the ASK1-p38/JNK, a downstream signaling pathway of Dusp9, which regulates inflammation and apoptosis. Our study highlights the multifaceted benefits of CAFF in treating MASH by rescuing hepatic Dusp9 expression, thereby reversing glycolipid metabolism disorders, liver inflammation, and fibrosis. These findings provide experimental evidence supporting the clinical and daily use of CAFF and black coffee in managing MASH patients.

Caffeine intake is nonlinearly associated with muscle mass in young and middle-aged US adults

BACKGROUND

Recent studies have indicated that coffee consumption is inversely correlated with sarcopenia in the elderly population. Data regarding the association between caffeine intake and muscle mass in young adults are scarce.

OBJECTIVE

We aimed to investigate how dietary caffeine correlates with muscle mass and sarcopenia in the young and middle-aged people.

METHODS

We performed a cross-sectional study utilizing data from NHANES. Muscle mass was evaluated using DXA and caffeine intake was derived from 24-h dietary recalls. Multivariable regression analysis was adopted to explore association between caffeine and sarcopenia. Restricted cubic spline analysis was conducted to investigate dose-response effect of dietary caffeine on muscle mass. Mediation effect of high-sensitivity C reactive protein was examined by mediation analysis.

RESULTS

A total of 9116 adults aged from 20 to 59 years old were included. Higher ingestion of caffeine was not associated with sarcopenia. Association between dietary caffeine and muscle mass was found to be W-shaped in males and U-shaped in young females, wherein mediation effect of hs-CRP was not discovered.

CONCLUSIONS

Caffeine consumption is associated with muscle mass in a nonlinear pattern. ASMI peaks at a daily caffeine intake of 1.23 mg/kg in young adults, while 0.64-1.49 mg/kg is recommended for middle-aged men.

Unlocking Cholesterol Metabolism in Metabolic-Associated Steatotic Liver Disease: Molecular Targets and Natural Product Interventions

Metabolic-associated steatotic liver disease (MASLD), the hepatic manifestation of metabolic syndrome, represents a growing global health concern. The intricate pathogenesis of MASLD, driven by genetic, metabolic, epigenetic, and environmental factors, leads to considerable clinical variability. Dysregulation of hepatic lipid metabolism, particularly cholesterol homeostasis, is a critical factor in the progression of MASLD and its more severe form, metabolic dysfunction-associated steatohepatitis (MASH). This review elucidates the multifaceted roles of cholesterol metabolism in MASLD, focusing on its absorption, transportation, biosynthesis, efflux, and conversion. We highlight recent advancements in understanding these processes and explore the therapeutic potential of natural products such as curcumin, berberine, and resveratrol in modulating cholesterol metabolism. By targeting key molecular pathways, these natural products offer promising strategies for MASLD management. Finally, this review also covers the clinical studies of natural products in MASLD, providing new insights for future research and clinical applications.

Preventive effects of caffeine on nicotine plus high-fat diet-induced hepatic steatosis and gain weight: a possible explanation for why obese smokers with high coffee consumption tend to be leaner

Non-alcoholic fatty liver disease (NAFLD) is a prevalent liver disorder, affecting approximately 25 % of the population. Coffee-drinking obese smokers exhibit lower body weights and decreased NAFLD rates, but the reasons behind this remain unclear. Additionally, the effect of nicotine, the main component of tobacco, on the development of NAFLD is still controversial. Our study aimed to explore the possible reasons that drinking coffee could alleviate NAFLD and gain weight and identify the real role of nicotine in NAFLD of obese smokers. A NAFLD model in mice was induced by administering nicotine and a high-fat diet (HFD). We recorded changes in body weight and daily food intake, measured the weights of the liver and visceral fat, and observed liver and adipose tissue histopathology. Lipid levels, liver function, liver malondialdehyde (MDA), superoxide dismutase (SOD), serum inflammatory cytokine levels and the expression of hepatic genes involved in lipid metabolism were determined. Our results demonstrated that nicotine exacerbated the development of NAFLD and caffeine had a hepatoprotective effect on NAFLD. The administration of caffeine could ameliorate nicotine-plus-HFD-induced NAFLD by reducing lipid accumulation, regulating hepatic lipid metabolism, alleviating oxidative stress, attenuating inflammatory response and restoring hepatic functions. These results might explain why obese smokers with high coffee consumption exhibit the lower incidence rate of NAFLD and tend to be leaner. It is essential to emphasise that the detrimental impact of smoking on health is multifaceted. Smoking cessation remains the sole practical and effective strategy for averting the tobacco-related complications and reducing the risk of mortality.

Gallic Acid Can Promote Low-Density Lipoprotein Uptake in HepG2 Cells via Increasing Low-Density Lipoprotein Receptor Accumulation

Gallic acid (GA) is a type of polyphenolic compound that can be found in a range of fruits, vegetables, and tea. Although it has been confirmed it improves non-alcoholic fatty liver disease (NAFLD), it is still unknown whether GA can improve the occurrence of NAFLD by increasing the low-density lipoprotein receptor (LDLR) accumulation and alleviating cholesterol metabolism disorders. Therefore, the present study explored the effect of GA on LDLR and its mechanism of action. The findings indicated that the increase in LDLR accumulation in HepG2 cells induced by GA was associated with the stimulation of the epidermal growth factor receptor-extracellular regulated protein kinase (EGFR-ERK1/2) signaling pathway. When the pathway was inhibited by EGFR mab cetuximab, it was observed that the activation of the EGFR-ERK1/2 signaling pathway induced by GA was also blocked. At the same time, the accumulation of LDLR protein and the uptake of LDL were also suppressed. Additionally, GA can also promote the accumulation of forkhead box O3 (FOXO3) and suppress the accumulation of hepatocyte nuclear factor-1α (HNF1α), leading to the inhibition of proprotein convertase subtilisin/kexin 9 (PCSK9) mRNA expression and protein accumulation. This ultimately results in increased LDLR protein accumulation and enhanced uptake of LDL in cells. In summary, the present study revealed the potential mechanism of GA's role in ameliorating NAFLD, with a view of providing a theoretical basis for the dietary supplementation of GA.

New insights into metabolic dysfunction-associated steatotic liver disease and oxidative balance score

Background

The relationship between oxidative stress and metabolic dysfunction-associated steatotic liver disease (MASLD) has not been studied, which remains inadequately recognized. This is a cross-sectional study in a US adult population to explore the relationship between MASLD and oxidative balance scores (OBS), which containing integrating dietary nutrition and lifestyle factors.

Methods

We analyzed data from National Health and Nutrition Examination Survey during 2017-2018. Multivariate logistic regression, restricted cubic spline curve (RCS) and subgroup analysis were used to investigate the association between OBS and MASLD. Cox regression analysis was utilized to assess the association between OBS and all-cause mortality among individuals.

Results

The multivariable-adjusted odds ratio (OR) and 95% confidence interval (CI) for the highest quartile of OBS (Q4) was 0.30 (0.12, 0.77) (p = 0.012) compared to the lowest quartile of OBS (Q1). The RCS regression and subgroup analysis indicated an inverted relationship between OBS and the development of MASLD. The OBS Q4 group (HR: 0.15, 95% CI: 0.03-0.87; p = 0.035) exhibited a lower risk of all-cause death than the Q1 group.

Conclusion

OBS is statistically significantly and negatively correlated with the risk of MASLD and all-cause mortality in US adults. More prospective investigations are required to substantiate our findings.

Current therapeutic targets and multifaceted physiological impacts of caffeine

Caffeine, which shares consubstantial structural similarity with purine adenosine, has been demonstrated as a nonselective adenosine receptor antagonist for eliciting most of the biological functions at physiologically relevant dosages. Accumulating evidence supports caffeine's beneficial effects against different disorders, such as total cardiovascular diseases and type 2 diabetes. Conversely, paradoxical effects are also linked to caffeine ingestion in humans including hypertension-hypotension and tachycardia-bradycardia. These observations suggest the association of caffeine action with its ingested concentration and/or concurrent interaction with preferential molecular targets to direct explicit events in the human body. Thus, a coherent analysis of the functional targets of caffeine, relevant to normal physiology, and disease pathophysiology, is required to understand the pharmacology of caffeine. This review provides a broad overview of the experimentally validated targets of caffeine, particularly those of therapeutic interest, and the impacts of caffeine on organ-specific physiology and pathophysiology. Overall, the available empirical and epidemiological evidence supports the dose-dependent functional activities of caffeine and advocates for further studies to get insights into the caffeine-induced changes under specific conditions, such as asthma, DNA repair, and cancer, in view of its therapeutic applications.