Influence of intermittent fasting on autophagy in the liver

Impact of diet and exercise on mitochondrial quality and mitophagy in Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder that affects millions of people worldwide. It is characterized by the accumulation of beta-amyloid and phosphorylated tau, synaptic damage, and mitochondrial abnormalities in the brain, leading to the progressive loss of cognitive function and memory. In AD, emerging research suggests that lifestyle factors such as a healthy diet and regular exercise may play a significant role in delaying the onset and progression of the disease. Mitochondria are often referred to as the powerhouse of the cell, as they are responsible for producing the energy to cells, including neurons to maintain cognitive function. Our article elaborates on how mitochondrial quality and function decline with age and AD, leading to an increase in oxidative stress and a decrease in ATP production. Decline in mitochondrial quality can impair cellular functions contributing to the development and progression of disease with the loss of neuronal functions in AD. This article also covered mitophagy, the process by which damaged or dysfunctional mitochondria are selectively removed from the cell to maintain cellular homeostasis. Impaired mitophagy has been implicated in the progression and pathogenesis of AD. We also discussed the impact of impaired mitophagy implicated in AD, as the accumulation of damaged mitochondria can lead to increased oxidative stress. We expounded how dietary interventions and exercise can help to improve mitochondrial quality, and mitochondrial function and enhance mitophagy in AD. A diet rich in antioxidants, polyphenols, and mitochondria-targeted small molecules has been shown to enhance mitochondrial function and protect against oxidative stress, particularly in neurons with aged and mild cognitively impaired subjects and AD patients. Promoting a healthy lifestyle, mainly balanced diet and regular exercise that support mitochondrial health, in an individual can potentially delay the onset and progression of AD. In conclusion, a healthy diet and regular exercise play a crucial role in maintaining mitochondrial quality and mitochondrial function, in turn, enhancing mitophagy and synaptic activities that delay AD in the elderly populations.

Regulation of Metabolic Aging Through Adenosine Mono Phosphate-Activated Protein Kinase and Mammalian Target of Rapamycin: A Comparative Study of Intermittent Fasting Variations in Obese Young Women

Background/Objectives: Obesity accelerates metabolic aging through oxidative stress, inflammation, and mitochondrial dysfunction. AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) are nutrient-sensing pathways regulating metabolism. AMPK promotes energy metabolism and autophagy, while excessive mTOR activity contributes to aging. Intermittent fasting (IF), including time-restricted feeding (TRF)-limiting food intake to a 6 h window (18:6)-and alternate-day modified fasting (ADMF)-alternating 24 h fasting (≤25% daily caloric intake) with unrestricted feeding-may improve metabolic regulation. However, their effects on AMPK, mTOR, and metabolic age remain unclear. Methods: This quasi-experimental pre-test-post-test control group study compared the TRF and ADMF on metabolic age, AMPK, and mTOR in young obese women. Twenty-four participants (mean age: 21.29 ± 1.76 years; body fat: 36.92 ± 3.18%; BMI: 29.68 ± 3.70 kg/m2) were initially matched by BMI and assigned to Control, TRF, and ADMF groups. A total of 4 participants (1 Control, 3 ADMF) were excluded due to outlier values, yielding final group sizes: Control (n = 7), TRF (n = 8), and ADMF (n = 5). The intervention lasted 20 days. Results: A significant decrease in AMPK levels was observed in the ADMF group (p = 0.043), while changes in the TRF and Control groups were not significant. mTOR levels showed a decreasing trend but were not statistically significant. No significant changes were found in metabolic age. Conclusions: Twenty days of intermittent fasting intervention did not significantly affect AMPK, mTOR, or metabolic age in young obese women. TRF may more effectively enhance AMPK and reduce mTOR, while ADMF may better reduce metabolic age.

Molecular mechanisms of pyroptosis in non-alcoholic steatohepatitis and feasible diagnosis and treatment strategies

Pyroptosis is a distinct form of cell death that plays a critical role in intensifying inflammatory responses. It primarily occurs via the classical pathway, non-classical pathway, caspase-3/6/7/8/9-mediated pathways, and granzyme-mediated pathways. Key effector proteins involved in the pyroptosis process include gasdermin family proteins and pannexin-1 protein. Pyroptosis is intricately linked to the onset and progression of non-alcoholic steatohepatitis (NASH). During the development of NASH, factors such as pyroptosis, innate immunity, lipotoxicity, endoplasmic reticulum stress, and gut microbiota imbalance interact and interweave, collectively driving disease progression. This review analyzes the molecular mechanisms of pyroptosis and its role in the pathogenesis of NASH. Furthermore, it explores potential diagnostic and therapeutic strategies targeting pyroptosis, offering new avenues for improving the diagnosis and treatment of NASH.

Effects of Intermittent Fasting on Liver Steatosis and Fibrosis, Serum FGF-21 and Autophagy Markers in Metabolic Dysfunction-Associated Fatty Liver Disease: A Randomized Controlled Trial

BACKGROUND

This randomized controlled study sought to determine the effect of intermittent fasting on anthropometric measurements, fibroblast growth factor (FGF)-21, and autophagy markers, as well as on hepatic steatosis and fibrosis levels in overweight or obese patients with metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

Patients were randomly assigned into two groups: received a dietary treatment involving 22-25 kcal/kg/day of energy for 8 weeks and followed the same dietary intervention and a 16:8 pattern. The extent of hepatic steatosis and fibrosis was determined using transient elastography on a FibroScan® device. The controlled attenuation parameter (CAP) and liver stiffness measurement (LSM), determined by transient elastography, reflect hepatic steatosis and fibrosis, respectively. In duplicate, serum levels of FGF-21, Beclin-1, and ATG-5 were determined using enzyme-linked immunosorbent assay.

RESULTS

The study included 48 patients with a mean age of 48.2 ± 1.4 years (27 female and 21 male). Improvements in anthropometric measurement and CAP and LSM levels and a decrease in serum FGF-21 levels were found in both groups (p < 0.05). Changes in the CAP and FGF-21 levels were higher in the energy + time-restricted diet group (p < 0.05). Autophagy-related protein (ATG)-5 levels increased only in the energy + time-restricted diet group [(0.74 (0.46-1.29) ng/mL vs. 0.95 (0.73-1.32) ng/mL, p = 0.03].

CONCLUSIONS

Intermittent fasting was potentially practical in the management of MAFLD. In particular, changes in FGF-21 and ATG-5 levels indicate the potential of intermittent fasting to regulate metabolic processes and autophagy. However, methodological limitations should be taken into consideration when interpreting the study results.

Chronic stress induces depression-like behavior in rats through affecting brain mitochondrial function and inflammation

Chronic stress is involved in pathophysiology of depression, and causes some neurochemical alterations in brain. Both mitochondrial dysfunction and neuroinflammation are implicated in mediating the depression-like behavior. The objectives of present study were, at first, to confirm that chronic unpredictable mild stress (CUMS) induces depression-like behavior and alters mitochondrial function and inflammatory responses within the brain, and then to explore the role of mitochondria in the development of this depression-like behavior. It has been found that CUMS exposure induced depression-like behavior, mitochondrial dysfunction, increased IL-1, IL-6, IFN-γ and TNF-α levels in hippocampus and PFC. Moreover, the level of ATP, the key index of mitochondrial function, was inversely correlated with the levels of proinflammatory cytokine. Intracerebroventricular (ICV) injection of the mitochondrial targeted antioxidant MnTBAP significantly alleviated depression-like behavior in CUMS group. These findings suggested that CUMS results in depression-like behavior, mitochondrial dysfunction as well as neuroinflammation, and mitochondria dysfunction contributes to depression-like behavior caused by CUMS.

Dietary Restrictions and Cancer Prevention: State of the Art

Worldwide, almost 10 million cancer deaths occurred in 2022, a number that is expected to rise to 16.3 million by 2040. Primary prevention has long been acknowledged as a crucial approach to reducing cancer incidence. In fact, between 30 and 50 percent of all tumors are known to be preventable by eating a healthy diet, staying active, avoiding alcohol, smoking, and being overweight. Accordingly, many international organizations have created tumor prevention guidelines, which underlie the importance of following a diet that emphasizes eating plant-based foods while minimizing the consumption of red/processed meat, sugars, processed foods, and alcohol. However, further research is needed to define the relationship between the effect of specific diets or nutritional components on cancer prevention. Interestingly, reductions in food intake and dietetic restrictions can extend the lifespan of yeast, nematodes, flies, and rodents. Despite controversial results in humans, those approaches have the potential to ameliorate health via direct and indirect effects on specific signaling pathways involved in cancer onset. Here, we describe the latest knowledge on the cancer-preventive potential of dietary restrictions and the biochemical processes involved. Molecular, preclinical, and clinical studies evaluating the effects of different fasting strategies will also be reviewed.

Effectiveness of Early Versus Late Time-Restricted Eating Combined with Physical Activity in Overweight or Obese Women

AIMS

To evaluate the effectiveness of a dual approach involving time-restricted eating (TRE) at different times of the day combined with physical activity (PA) on functional capacity and metabolic health in overweight or obese women.

METHODS

Random allocation of sixty-one participants into four groups: early time-restricted eating plus physical activity (ETRE-PA, n = 15, 31.8 ± 10.76 years, 89.68 ± 13.40 kg, 33.5 ± 5.53 kg/m2), late time-restricted eating with physical activity (LTRE-PA, n = 15, 30.60 ± 7.94 years, 94.45 ± 15.36 kg, 34.37 ± 7.09 kg/m2), late time-restricted eating only (LTRE, n = 15, 27.93 ± 9.79 years, 88.32 ± 10.36 kg, 32.71 ± 5.15 kg/m2) and a control group (CG, n = 15, 36.25 ± 11.52 years, 89.01 ± 11.68 kg, 33.66 ± 6.18 kg/m2). The intervention lasted for 12 weeks in all groups. Both the ETRE-PA and LTRE-PA groups engaged in a rigorous combined aerobic and resistance-training program.

RESULTS

Significant reductions in body weight and body mass index were observed in the ETRE-PA and LTRE-PA groups compared to the CG and LTRE groups post-intervention (p < 0.0005). Only the ETRE-PA group exhibited a significant decrease in fat mass (p = 0.02), low-density lipoprotein cholesterol (p = 0.01), and aspartate aminotransferase (p = 0.002). Significant reductions in alanine aminotransferase levels were observed in the ETRE-PA (p = 0.004) and LTRE-PA (p = 0.02) groups. These two latter groups achieved higher performances in the 6-min walking test, bench press, 30-s squat, crunch test, vertical jump (p < 0.0005 for both), and leg extension (p < 0.02 for both) when compared to the LTRE and CG groups.

CONCLUSION

The integration of TRE with PA leads to greater improvements in body composition, lipid profile, and physical performance, with no significant differences between the ETRE-PA and LTRE-PA approaches. This combined strategy offers a promising solution for overweight and obese women.

Fasting as an Adjuvant Therapy for Cancer: Mechanism of Action and Clinical Practice

The fundamental biological characteristics of tumor cells are characterized by irregularities in signaling and metabolic pathways, which are evident through increased glucose uptake, altered mitochondrial function, and the ability to evade growth signals. Interventions such as fasting or fasting-mimicking diets represent a promising strategy that can elicit distinct responses in normal cells compared to tumor cells. These dietary strategies can alter the circulating levels of various hormones and metabolites, including blood glucose, insulin, glucagon, growth hormone, insulin-like growth factor, glucocorticoids, and epinephrine, thereby potentially exerting an anticancer effect. Additionally, elevated levels of insulin-like growth factor-binding proteins and ketone bodies may increase tumor cells' dependence on their own metabolites, ultimately leading to their apoptosis. The combination of fasting or fasting-mimicking diets with radiotherapy or chemotherapeutic agents has demonstrated enhanced anticancer efficacy. This paper aims to classify fasting, elucidate the mechanisms that underlie its effects, assess its impact on various cancer types, and discuss its clinical applications. We will underscore the differential effects of fasting on normal and cancer cells, the mechanisms responsible for these effects, and the imperative for clinical implementation.

Autophagy and hepatic lipid metabolism: mechanistic insight and therapeutic potential for MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) originates from a homeostatic imbalance in hepatic lipid metabolism. Increased fat deposition in the liver of people suffering from MASLD predisposes them to develop further metabolic derangements, including diabetes mellitus, metabolic dysfunction-associated steatohepatitis (MASH), and other end-stage liver diseases. Unfortunately, only limited pharmacological therapies exist for MASLD to date. Autophagy, a cellular catabolic process, has emerged as a primary mechanism of lipid metabolism in mammalian hepatocytes. Furthermore, preclinical studies with autophagy modulators have shown promising results in resolving MASLD and mitigating its progress into deleterious liver pathologies. In this review, we discuss our current understanding of autophagy-mediated hepatic lipid metabolism, its therapeutic modulation for MASLD treatment, and current limitations and scope for clinical translation.

The Influence of Diet and Its Components on the Development and Prevention of Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is diagnosed annually in nearly a million people worldwide, with approximately half of them being diagnosed at an advanced stage of the disease. Non-infectious risk factors for the development of HCC include an unbalanced lifestyle, including poor dietary choices characterized by a low intake of antioxidants, such as vitamins E and C, selenium, and polyphenols, as well as an excessive consumption of energy and harmful substances. Repeated bad dietary choices that contribute to an unbalanced lifestyle lead to the accumulation of fatty substances in the liver and to it entering an inflammatory state, which, without intervention, results in cirrhosis, the main cause of HCC. This review of the English language literature aims to present the food components that, when included in the daily diet, reduce the risk of developing HCC, as well as identifying foods that may have a carcinogenic effect on liver cells.

Cell-type specific role of autophagy in the liver and its implications in non-alcoholic fatty liver disease

Autophagy, a cellular degradative process, has emerged as a key regulator of cellular energy production and stress mitigation. Dysregulated autophagy is a common phenomenon observed in several human diseases, and its restoration offers curative advantage. Non-alcoholic fatty liver disease (NAFLD), more recently renamed metabolic dysfunction-associated steatotic liver disease, is a major metabolic liver disease affecting almost 30% of the world population. Unfortunately, NAFLD has no pharmacological therapies available to date. Autophagy regulates several hepatic processes including lipid metabolism, inflammation, cellular integrity and cellular plasticity in both parenchymal (hepatocytes) and non-parenchymal cells (Kupffer cells, hepatic stellate cells and sinusoidal endothelial cells) with a profound impact on NAFLD progression. Understanding cell type-specific autophagy in the liver is essential in order to develop targeted treatments for liver diseases such as NAFLD. Modulating autophagy in specific cell types can have varying effects on liver function and pathology, making it a promising area of research for liver-related disorders. This review aims to summarize our present understanding of cell-type specific effects of autophagy and their implications in developing autophagy centric therapies for NAFLD.

The Role of Sirtuin-1 (SIRT1) in the Physiology and Pathophysiology of the Human Placenta

Sirtuins, especially SIRT1, play a significant role in regulating inflammatory response, autophagy, and cell response to oxidative stress. Since their discovery, sirtuins have been regarded as anti-ageing and longevity-promoting enzymes. Sirtuin-regulated processes seem to participate in the most prevalent placental pathologies, such as pre-eclampsia. Furthermore, more and more research studies indicate that SIRT1 may prevent pre-eclampsia development or at least alleviate its manifestations. Having considered this, we reviewed recent studies on the role of sirtuins, especially SIRT1, in processes determining normal or abnormal development and functioning of the placenta.