Fasting Therapy Contributes to the Improvement of Endothelial Function and Decline in Vascular Injury-Related Markers in Overweight and Obese Individuals via Activating Autophagy of Endothelial Progenitor Cells

The Role of Autophagy in Vascular Endothelial Cell Health and Physiology

Autophagy is a highly conserved cellular recycling process which enables eukaryotes to maintain both cellular and overall homeostasis through the catabolic breakdown of intracellular components or the selective degradation of damaged organelles. In recent years, the importance of autophagy in vascular endothelial cells (ECs) has been increasingly recognized, and numerous studies have linked the dysregulation of autophagy to the development of endothelial dysfunction and vascular disease. Here, we provide an overview of the molecular mechanisms underlying autophagy in ECs and our current understanding of the roles of autophagy in vascular biology and review the implications of dysregulated autophagy for vascular disease. Finally, we summarize the current state of the research on compounds to modulate autophagy in ECs and identify challenges for their translation into clinical use.

Caloric restriction, Sirtuins, and cardiovascular diseases

ABSTRACT

Caloric restriction (CR) is a well-established dietary intervention known to extend healthy lifespan and exert positive effects on aging-related diseases, including cardiovascular conditions. Sirtuins, a family of nicotinamide adenine dinucleotide (NAD + )-dependent histone deacetylases, have emerged as key regulators of cellular metabolism, stress responses, and the aging process, serving as energy status sensors in response to CR. However, the mechanism through which CR regulates Sirtuin function to ameliorate cardiovascular disease remains unclear. This review not only provided an overview of recent research investigating the interplay between Sirtuins and CR, specifically focusing on their potential implications for cardiovascular health, but also provided a comprehensive summary of the benefits of CR for the cardiovascular system mediated directly via Sirtuins. CR has also been shown to have considerable impact on specific metabolic organs, leading to the production of small molecules that enter systemic circulation and subsequently regulate Sirtuin activity within the cardiovascular system. The direct and indirect effects of CR offer a potential mechanism for Sirtuin modulation and subsequent cardiovascular protection. Understanding the interplay between CR and Sirtuins will provide new insights for the development of interventions to prevent and treat cardiovascular diseases.

Endothelial progenitor cells as an emerging cardiovascular risk factor in the field of food and nutrition research: advances and challenges

Dietary modifications can help prevent many cardiovascular disease (CVD) events. Endothelial progenitor cells (EPCs) actively contribute to cardiovascular system maintenance and could function as surrogate markers for evaluating improvement in cardiovascular health resulting from nutritional interventions. This review summarizes the latest research progress on the impact of food and nutrients on EPCs, drawing on evidence from human, animal, and in vitro studies. Additionally, current trends and challenges faced in the field are highlighted. Findings from studies examining cells as EPCs are generally consistent, demonstrating that a healthy diet, such as the Mediterranean diet or a supervised diet for overweight people, specific foods like olive oil, fruit, vegetables, red wine, tea, chia, and nutraceuticals, and certain nutrients such as polyphenols, unsaturated fats, inorganic nitrate, and vitamins, generally promote higher EPC numbers and enhanced EPC function. Conversely, an unhealthy diet, such as one high in sugar substitutes, salt, or fructose, impairs EPC function. Research on outgrowth EPCs has revealed that various pathways are involved in the modulation effects of food and nutrients. The potential of EPCs as a biomarker for assessing the effectiveness of nutritional interventions in preventing CVDs is immense, while further clarification on definition and characterization of EPCs is required.

Effects of intermittent fasting on cognitive health and Alzheimer's disease

OBJECTIVE

Caloric restriction by intermittent fasting produces several metabolic changes, such as increased insulin sensitivity and use of ketone bodies as energy sources. In humans, intermittent fasting has been studied in hypertension, diabetes, and related conditions, but, to date, not as a strategy to reduce the risk of emergent dementia. In this scoping review, the relevance of intermittent fasting as a potential preventive intervention for Alzheimer's dementia is explored.

BACKGROUND

The beneficial effects of calorie restriction have been documented in animals and humans. Decreased oxidative stress damage and attenuated inflammatory responses are associated with intermittent fasting. These changes have a favorable impact on the vascular endothelium and stress-induced cellular adaptation.

RESULTS

Physiological alterations associated with fasting have profound implications for pathological mechanisms associated with dementias, particularly Alzheimer's disease. Compared with ad libitum feeding, caloric restriction in animals was associated with a reduction in β-amyloid accumulation, which is the cardinal pathological marker of Alzheimer's disease. Animal studies have demonstrated synaptic adaptations in the hippocampus and enhanced cognitive function after fasting, consistent with these theoretical frameworks. Furthermore, vascular dysfunction plays a crucial role in Alzheimer's disease pathology, and intermittent fasting promotes vascular health.

CONCLUSIONS

These observations lead to a hypothesis that intermittent fasting over the years will potentially reverse or delay the pathological process in Alzheimer's disease.

Improvement in endothelial function in hypertensive patients after Ramadan fasting: effects of cortisol

BACKGROUND

There are studies on the effects of Ramadan fasting (RF), which is one of the intermittent fasting diets, on both hypertension and endothelial function. However, the relationship between possible improvements in endothelial function and blood pressure after RF is not clear. In this study, we aimed to evaluate the effects of RF on blood pressure and endothelial dysfunction in patients with arterial hypertension (HT).

METHODS

: Sixty-four HT patients, aged 45-65, who were followed up in the Cardiology Department of Kayseri City Hospital and fasted during Ramadan between 13 April and 13 May 2021 with their self-consents were enrolled to study. Body mass index (BMI), blood pressure, and flow-mediated dilatation (FMD) were assessed before and after Ramadan. Also, 5 mL venous blood samples were taken between 8:00 and 8:30 a.m. from all participants to assess cortisol, C-reactive protein (CRP), and other laboratory data.

RESULTS

: In patients, FMD values were found to be higher after Ramadan compared to values before the fasting period (p < 0.001). CRPand cortisol levels decreased after fasting, and the decrease in CRP (95% CI for B = -1.685 - -0.334, p = 0.009) and cortisol levels (95% CI for B = -0.392 - 0.092, p = 0.039) were determined as the predictive factors for FMD after RF.

DISCUSSION

Endothelial functions as determined by FMD improved after 30 days of intermittent fasting. The decreased CRP and cortisol levels may contribute to the improvement in FMD after RF.

Urotensin receptor acts as a novel target for ameliorating fasting-induced skeletal muscle atrophy

Urotensin receptor (UT) is a G-protein-coupled receptor, whose endogenous ligand is urotensin-II (U-II). Skeletal muscle mass is regulated by various conditions, such as nutritional status, exercise, and diseases. Previous studies have pointed out that the urotensinergic system is involved in skeletal muscle metabolism and function, but its mechanism remains unclear, especially given the lack of research on the effect and mechanism of fasting. In this study, UT receptor knockout mice were generated to evaluate whether UT has effects on fasting induced skeletal muscle atrophy. Furthermore, the UT antagonist palosuran (3, 10, 30mg/kg) was intraperitoneally administered daily for 5 days to clarify the therapeutic effect of UT antagonism. Our results found the mice that fasted for 48hours exhibited skeletal muscle atrophy, accompanied by enhanced U-II levels in both skeletal muscles and blood. UT receptor knockout effectively prevented fasting-induced skeletal muscle atrophy. The UT antagonist ameliorated fasting-induced muscle atrophy in mice as determined by increased muscle strengths, weights, and muscle fiber areas (including fast, slow, and mixed types). In addition, the UT antagonist reduced skeletal muscle atrophic markers, including F-box only protein 32 (FBXO32) and tripartite motif containing 63 (TRIM63). Moreover, the UT antagonist was also observed to enhance PI3K/AKT/mTOR while inhibiting autophagy signaling. In summary, our study provides the first evidence that UT antagonism may represent a novel therapeutic approach for the treatment of fasting-induced skeletal muscle atrophy.

Fasting-Mimicking Diet Reduces Trimethylamine N-Oxide Levels and Improves Serum Biochemical Parameters in Healthy Volunteers

Elevated plasma levels of trimethylamine N-oxide (TMAO) have been proposed as a diet-derived biomarker of cardiometabolic disease risk. Caloric restriction is the most common dietary intervention used to improve cardiometabolic health; however, novel trends suggest a fasting-mimicking diet (FMD) as a more feasible alternative. FMD is a variation of intermittent fasting, based on caloric restriction and limitation of protein sources of animal origin, applied in daily cycles during a 5-day period. As TMAO is intensively produced by gut microbiota after the consumption of animal-derived products, we aim to investigate whether a 5-day FMD affects plasma TMAO levels and markers of metabolic health. To investigate whether an increase in vegetable intake possesses similar effects on TMAO levels and metabolic parameters, healthy volunteers (n = 24) were subjected to a 5-day FMD and 19 volunteers served as a reference group (VEG). This group of volunteers consumed an additional four servings of vegetables per day, but otherwise stayed on their usual diet. FMD resulted in a twofold decrease in plasma TMAO levels, which was not evident in the volunteers from the VEG group. Moreover, FMD led to a weight loss of 2.8 ± 0.2 kg and a subsequent reduction in BMI compared to baseline. The FMD group exhibited a significant elevation in plasma ketone bodies (14-fold compared to baseline) and a decrease in IGF-1 levels by 37 ± 8 ng/mL. Since fasting glucose and C-peptide levels decreased, all volunteers in the FMD group showed improved insulin sensitivity and a decreased HOMA-IR index. In contrast, in the VEG group, only a slight reduction in plasma levels of fasting glucose and triglycerides was noted. In conclusion, we show that FMD is a viable strategy to reduce plasma levels of TMAO by limiting caloric intake and animal-derived protein consumption. The reduction in the level of TMAO could be an additional benefit of FMD, leading to a reduced risk of cardiometabolic diseases.

Association of enhanced circulating trimethylamine N-oxide with vascular endothelial dysfunction in periodontitis patients

BACKGROUND

Accumulating evidences indicate that periodontitis is closely associated with endothelial dysfunction. Trimethylamine-N-oxide (TMAO), a harmful microbiota generated metabolite, has been implicated as a nontraditional risk factor for impaired endothelial function. However, whether increased circulating levels of TMAO in periodontitis patients induces endothelial dysfunction remains unknown.

METHODS

Patients with periodontitis and periodontally healthy controls were enrolled. Periodontal inflamed surface area (PISA) was calculated to assess the inflammatory burden posed by periodontitis. The circulating TMAO was measured by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Vascular endothelial function including peripheral endothelial progenitor cells (EPCs), brachial arterial flow-mediated vasodilation (FMD), and brachial-ankle pulse wave velocity (baPWV) were assessed. We also isolated and cultured EPCs from participants' peripheral blood to investigate the effect of TMAO on EPC functions in vitro.

RESULTS

One hundred and twenty two patients with Stage III-IV periodontitis and 81 healthy controls were included. Patients with periodontitis presented elevated TMAO (P = 0.002), lower EPCs (P = 0.025), and declined FMD levels (P = 0.005). The TMAO concentrations were correlated with reduced circulating EPCs and FMD levels. Moreover, TMAO can injury EPCs function in vitro, and may induce cell pyroptosis via Bax/caspase-3/GSDME pathway.

CONCLUSIONS

The present study demonstrates for the first time that circulating TMAO levels are increased in patients with Stage III-IV periodontitis, and correlated with vascular endothelial dysfunction. These findings may provide a novel insight into the mechanism of vascular endothelial dysfunction in patient with periodontitis via TMAO-downregulated EPC functions.