Dietary Intake Regulates White Adipose Tissues Angiogenesis via Liver Fibroblast Growth Factor 21 in Male Mice

The regulatory effect of intermittent fasting on inflammasome activation in health and disease

Intermittent fasting (IF), one of the most popular diets, can regulate inflammation and promote health; however, the detailed molecular mechanisms are not fully understood. The present review aims to provide an overview of recent preclinical and clinical studies that have examined the effect of IF on inflammasome signaling, and to discuss the translational gap between preclinical and clinical studies. Three databases (PubMed, Web of Science, and Embase) were searched to identify all relevant preclinical and clinical studies up to October 30, 2022. A total of 1544 studies were identified through the database searches, and 29 preclinical and 10 clinical studies were included. Twenty-three of the 29 preclinical studies reported that IF treatment could reduce inflammasome activation in neurological diseases, metabolic and cardiovascular diseases, immune and inflammatory diseases, gastrointestinal diseases, and pulmonary diseases, and 7 of the 10 clinical studies demonstrated reduced inflammasome activation after IF intervention in both healthy and obese participants. Among various IF regimens, time-restricted eating seemed to be the most effective one in terms of inflammasome regulation, and the efficacy of IF might increase over time. This review highlights the regulatory effect of IF on inflammasome activation in health and disease. Future studies using different IF regimens, in various populations, are needed in order to evaluate its potential to be used alone or as an adjunct therapy in humans to improve health and counteract diseases.

Fibroblast growth factor 21: An emerging pleiotropic regulator of lipid metabolism and the metabolic network

Fibroblast growth factor 21 (FGF21) was originally identified as an important metabolic regulator which plays a crucial physiological role in regulating a variety of metabolic parameters through the metabolic network. As a novel multifunctional endocrine growth factor, the role of FGF21 in the metabolic network warrants extensive exploration. This insight was obtained from the observation that the FGF21-dependent mechanism that regulates lipid metabolism, glycogen transformation, and biological effectiveness occurs through the coordinated participation of the liver, adipose tissue, central nervous system, and sympathetic nerves. This review focuses on the role of FGF21-uncoupling protein 1 (UCP1) signaling in lipid metabolism and how FGF21 alleviates non-alcoholic fatty liver disease (NAFLD). Additionally, this review reveals the mechanism by which FGF21 governs glucolipid metabolism. Recent research on the role of FGF21 in the metabolic network has mostly focused on the crucial pathway of glucolipid metabolism. FGF21 has been shown to have multiple regulatory roles in the metabolic network. Since an adequate understanding of the concrete regulatory pathways of FGF21 in the metabolic network has not been attained, this review sheds new light on the metabolic mechanisms of FGF21, explores how FGF21 engages different tissues and organs, and lays a theoretical foundation for future in-depth research on FGF21-targeted treatment of metabolic diseases.

Risks and Benefits of Intermittent Fasting for the Aging Cardiovascular System

Population aging and the associated increase in cardiovascular disease rates pose serious threats to global public health. Different forms of fasting have become an increasingly attractive strategy to directly address aging and potentially limit or delay the onset of cardiovascular diseases. A growing number of experimental studies and clinical trials indicate that the amount and timing of food intake as well as the daily time window during which food is consumed, are crucial determinants of cardiovascular health. Indeed, intermittent fasting counteracts the molecular hallmarks of cardiovascular aging and promotes different aspects of cardiometabolic health, including blood pressure and glycemic control, as well as body weight reduction. In this report, we summarize current evidence from randomized clinical trials of intermittent fasting on body weight and composition as well as cardiovascular and metabolic risk factors. Moreover, we critically discuss the preventive and therapeutic potential of intermittent fasting, but also possible detrimental effects in the context of cardiovascular aging and related disease. We delve into the physiological mechanisms through which intermittent fasting might improve cardiovascular health, and raise important factors to consider in the design of clinical trials on the efficacy of intermittent fasting to reduce major adverse cardiovascular events among aged individuals at high risk of cardiovascular disease. We conclude that despite growing evidence and interest among the lay and scientific communities in the cardiovascular health-improving effects of intermittent fasting, further research efforts and appropriate caution are warranted before broadly implementing intermittent fasting regimens, especially in elderly persons.

Effects and possible mechanisms of intermittent fasting on health and disease: a narrative review

The imbalance between energy intake and expenditure in an environment of continuous food availability can lead to metabolic disturbances in the body and increase the risk of obesity and a range of chronic noncommunicable diseases. Intermittent fasting (IF) is one of the most popular nonpharmacological interventions to combat obesity and chronic noncommunicable diseases. The 3 most widely studied IF regimens are alternate-day fasting, time-restricted feeding, and the 5:2 diet. In rodents, IF helps optimize energy metabolism, prevent obesity, promote brain health, improve immune and reproductive function, and delay aging. In humans, IF's benefits are relevant for the aging global population and for increasing human life expectancy. However, the optimal model of IF remains unclear. In this review, the possible mechanisms of IF are summarized and its possible drawbacks are discussed on the basis of the results of existing research, which provide a new idea for nonpharmaceutical dietary intervention of chronic noncommunicable diseases.

FGF21 promotes myocardial angiogenesis and mediates the cardioprotective effects of exercise in myocardial infarction mice

The mechanism by which aerobic exercise promotes cardiac function after myocardial infarction (MI) is still not fully understand. In this study, we investigated the role of fibroblast growth factor 21 (FGF21) in exercise protecting the cardiac function of MI mice. In vivo, MI was induced by left anterior descending coronary artery ligation in wild-type and fgf21 knockout mice on the C57BL/6 background. One week after MI, the mice underwent aerobic exercise for 4 wk. In vitro, human umbilical vein endothelial cells (HUVECs) were treated with H2O2, recombinant human FGF21 (rhFGF21), fibroblast growth factor receptor 1 (FGFR1) inhibitor (PD166866), and phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002) to explore the potential mechanisms. Scratch wound healing and tubule formation analysis were used to detect the migration and tubule formation ability of HUVECs. Our results showed that aerobic exercise significantly promoted angiogenesis and cardiac function through enhancing the expression of FGF21 and activating FGFR1/PI3K/AKT/VEGF pathway. But such changes in cardiac from aerobic exercise were attenuated by fgf21 knockout mice. 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) enhanced angiogenesis and cell migration through FGF21/FGFR1/PI3K/AKT/VEGF signaling pathway. Under the intervention of H2O2, rhFGF21 also played the role of promoting angiogenesis and cell migration through the same mechanism. In conclusion, our results showed that FGF21 promoted the aerobic exercise-induced angiogenesis and improved cardiac function via FGFR1/PI3K/AKT/VEGF signal in MI mice.NEW & NOTEWORTHY FGF21 activated FGFR1/PI3K/AKT/VEGF signaling pathway mediated angiogenesis in MI mice. FGF21 deficiency attenuated aerobic exercise-induced cardiac angiogenesis in MI mice. FGF21/FGFR1/PI3K/AKT/VEGF signal played an important role in aerobic exercise to promote myocardial angiogenesis and improved cardiac function.

Dietary Protein Regulates Female Estrous Cyclicity Partially via Fibroblast Growth Factor 21

Fibroblast growth factor 21 (FGF21), a hormone predominantly released in the liver, has emerged as a critical endocrine signal of dietary protein intake, but its role in the control of estrous cyclicity by dietary protein remains uncertain. To investigated the role of FGF21 and hypothalamic changes in the regulation of estrous cyclicity by dietary protein intake, female adult Sprague-Dawley rats with normal estrous cycles were fed diets with protein contents of 4% (P4), 8% (P8), 13% (P13), 18% (P18), and 23% (P23). FGF21 liver-specific knockout or wild-type mice were fed P18 or P4 diets to examine the role of liver FGF21 in the control of estrous cyclicity. Dietary protein restriction resulted in no negative effects on estrous cyclicity or ovarian follicular development when the protein content was greater than 8%. Protein restriction at 4% resulted in decreased bodyweight, compromised Kiss-1 expression in the hypothalamus, disturbed estrous cyclicity, and inhibited uterine and ovarian follicular development. The disturbed estrous cyclicity in rats that received the P4 diet was reversed after feeding with the P18 diet. Liver Fgf21 mRNA expressions and serum FGF21 levels were significantly increased as dietary protein content decreased, and loss of hepatic FGF21 delayed the onset of cyclicity disruption in rats fed with the P4 diet, possibly due to the regulation of insulin-like growth factor-1. Collectively, severe dietary protein restriction results in the cessation of estrous cyclicity and ovarian follicle development, and hepatic FGF21 and hypothalamic Kiss-1 were partially required for this process.

Time-restricted feeding ameliorates uterine epithelial estrogen receptor α transcriptional activity at the time of embryo implantation in mice fed a high-fat diet

BACKGROUND

More than 30% of reproductive-age women are obese or overweight. Obesity and exposure to a high-fat diet (HFD) detrimentally affect endometrial development and embryo implantation. We previously reported that time-restricted feeding (TRF) improved ovarian follicular development, but whether and how TRF modulates embryo implantation are poorly understood.

OBJECTIVE

We investigated the effect of TRF on embryo implantation.

METHODS

In TRF group, mice had 10 hours of food free access from 9 pm to 7 am, and fed a normal diet or a HFD. Tail vein injection of Chicago blue dye was used to examine embryo implantation sites at day 5.5 (D5.5) of pregnancy. Serum collected at D0.5 and D4.5 of pregnancy was used to examine the level of estradiol (E2) and progesterone. Uterine estrogen receptor (ER) and progesterone receptor levels and their targeted aquaporins (AQPs) were measured. LC-MS was used to analyze bile acid (BA) composition, and primary hepatocytes were used to test the effects of BA on the expression level of SULT1E1, a key enzyme in estrogen inactivation and elimination.

RESULTS

We found that TRF prevented HFD-induced embryo loss and alleviated the defect in luminal closure on D4.5 of pregnancy. The cyclic changes of E2 level were lost in mice fed ad libitum but not in TRF mice on the HFD. The HFD increased ERα expression and transcriptional activity, which induced AQP3 and AQP5 expression on D4.5 of pregnancy. TRF prevented the negative effect of the HFD on uterine luminal closure. Furthermore, in vitro and in vivo results showed that BA suppressed estrogen degradation by activating liver SULT1E1 expression.

CONCLUSIONS

Our findings demonstrated that TRF prevented HFD-induced defects in luminal closure, thereby improving embryonic implantation, and provide novel insights into the effects of dietary intervention on obesity and associated infertility.

Fasting: From Physiology to Pathology

Overnutrition is a risk factor for various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. Therefore, targeting overnutrition represents a simple but attractive strategy for the treatment of these increasing public health threats. Fasting as a dietary intervention for combating overnutrition has been extensively studied. Fasting has been practiced for millennia, but only recently have its roles in the molecular clock, gut microbiome, and tissue homeostasis and function emerged. Fasting can slow aging in most species and protect against various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. These centuried and unfading adventures and explorations suggest that fasting has the potential to delay aging and help prevent and treat diseases while minimizing side effects caused by chronic dietary interventions. In this review, recent animal and human studies concerning the role and underlying mechanism of fasting in physiology and pathology are summarized, the therapeutic potential of fasting is highlighted, and the combination of pharmacological intervention and fasting is discussed as a new treatment regimen for human diseases.

Adipose endothelial cells mastering adipose tissues metabolic fate

Dynamic communication within adipose tissue depends on highly vascularized structural characteristics to maintain systemic metabolic homoeostasis. Recently, it has been noted that adipose endothelial cells (AdECs) act as essential bridges for biological information transmission between adipose-resident cells. Hence, paracrine regulators that mediate crosstalk between AdECs and adipose stromal cells were summarized. We also highlight the importance of AdECs to maintain adipocytes metabolic homoeostasis by regulating insulin sensitivity, lipid turnover and plasticity. The differential regulation of AdECs in adipose plasticity often depends on vascular density and metabolic states. Although choosing pro-angiogenic or anti-angiogenic therapies for obesity is still a matter of debate in clinical settings, the growing numbers of drugs have been confirmed to play an anti-obesity effect by affecting vascularization. Pharmacologic angiogenesis intervention has great potential as therapeutic strategies for obesity.

New developments in the biology of fibroblast growth factors

The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.

The Shades of Grey in Adipose Tissue Reprogramming

The adipose tissue (AT) has a major role in contributing to obesity-related pathologies through regulating systemic immunometabolism. The pathogenicity of the AT is underpinned by its remarkable plasticity to be reprogrammed during obesity, in the perspectives of tissue morphology, extracellular matrix (ECM) composition, angiogenesis, immunometabolic homoeostasis and circadian rhythmicity. Dysregulation in these features escalates the pathogenesis conferred by this endometabolic organ. Intriguingly, the potential to be reprogrammed appears to be an Achilles’ heel of the obese AT that can be targeted for the management of obesity and its associated comorbidities. Here, we provide an overview of the reprogramming processes of white AT (WAT), with a focus on their dynamics and pleiotropic actions over local and systemic homoeostases, followed by a discussion of potential strategies favouring therapeutic reprogramming. The potential involvement of AT remodelling in the pathogenesis of COVID-19 is also discussed.

Nutritional Regulation of Mammary Tumor Microenvironment

The mammary gland is a heterogeneous organ comprising of immune cells, surrounding adipose stromal cells, vascular cells, mammary epithelial, and cancer stem cells. In response to nutritional stimuli, dynamic interactions amongst these cell populations can be modulated, consequently leading to an alteration of the glandular function, physiology, and ultimately disease pathogenesis. For example, obesity, a chronic over-nutritional condition, is known to disrupt homeostasis within the mammary gland and increase risk of breast cancer development. In contrast, emerging evidence has demonstrated that fasting or caloric restriction can negatively impact mammary tumorigenesis. However, how fasting induces phenotypic and functional population differences in the mammary microenvironment is not well understood. In this review, we will provide a detailed overview on the effect of nutritional conditions (i.e., overnutrition or fasting) on the mammary gland microenvironment and its impact on mammary tumor progression.