Dihydromyricetin Improves High-Fat Diet-Induced Hyperglycemia through ILC3 Activation via a SIRT3-Dependent Mechanism

Multiple molecular and cellular mechanisms of the antitumour effect of dihydromyricetin (Review)

Dihydromyricetin (DHM) is a natural flavonoid compound with multiple antitumour effects, including inhibition of proliferation, promotion of apoptosis, inhibition of invasion and migration, clearance of reactive oxygen species (ROS) and induction of autophagy. For example, DHM can effectively block the progression of the tumour cell cycle and inhibit cell proliferation. In different types of cancer cells, DHM can regulate the PI3K/Akt pathway, mTOR, and NF-κB pathway components, such as p53, and endoplasmic reticulum stress can alter the accumulation of ROS or induce autophagy to promote the apoptosis of tumour cells. In addition, when DHM is used in combination with various known chemotherapy drugs, such as paclitaxel, nedaplatin, doxorubicin, oxaliplatin and vinblastine, it can increase the sensitivity of tumour cells to DHM and increase the therapeutic effect of chemotherapy drugs. In the present review, the multiple molecular and cellular mechanisms underlying the antitumour effect of DHM, as well as its ability to increase the effects of various traditional antitumour drugs were summarized. Through the present review, it is expected by the authors to draw attention to the potential of DHM as an antitumour drug and provide valuable references for the clinical translation of DHM research and the development of related treatment strategies.

A review on SIRT3 and its natural small molecule activators as a potential Preventive and therapeutic target

Sirtuins (SIRTs) were originally characterized by yeast Sir2 as a lifespan regulator that is conserved in all three structural domains of bacteria, archaea and eukaryotes and belong to histone deacetylases consisting of seven members (SIRT1-SIRT7). Surprisingly, SIRTs have been shown to play important regulatory roles in almost all cellular functions, including mitochondrial biogenesis, oxidative stress, inflammation, cell growth, energy metabolism, neural function, and stress resistance. Among the SIRT members, sirtuin 3 (SIRT3) is one of the most important deacetylases that regulates the mitochondrial acetylation and plays a role in pathological processes, such as metabolism, DNA repair, oxidative stress, apoptosis and ferroptosis. Therefore, SIRT3 is considered as a potential target for the treatment of a variety of pathological diseases, including metabolic diseases, neurodegenerative diseases, age-related diseases and others. Furthermore, the isolation, screening, and development of SIRT3 signaling agonists, especially from natural products, have become a widely investigated objective. This paper describes the structure of SIRT3 protein, discusses the pathological process of SIRT3-mediated acetylation modification, and reviews the role of SIRT3 in diseases, SIRT3 activators and its related disease studies.

Nanoscale coordination polymer Fe-DMY downregulating Poldip2-Nox4-H2O2 pathway and alleviating diabetic retinopathy

Diabetic retinopathy (DR) is a prevalent microvascular complication of diabetes and the leading cause of blindness and severe visual impairment in adults. The high levels of glucose trigger multiple intracellular oxidative stress pathways, such as POLDIP2, resulting in excessive reactive oxygen species (ROS) production and increased expression of vascular cell adhesion molecule-1 (VCAM-1), hypoxia-inducible factor 1α (HIF-1α), and vascular endothelial growth factor (VEGF), causing microvascular dysfunction. Dihydromyricetin (DMY) is a natural flavonoid small molecule antioxidant. However, it exhibits poor solubility in physiological environments, has a short half-life in vivo, and has low oral bioavailability. In this study, we present, for the first time, the synthesis of ultra-small Fe-DMY nano-coordinated polymer particles (Fe-DMY NCPs), formed by combining DMY with low-toxicity iron ions. In vitro and in vivo experiments confirm that Fe-DMY NCPs alleviate oxidative stress-induced damage to vascular endothelial cells by high glucose, scavenge excess ROS, and improve pathological features of DR, such as retinal vascular leakage and neovascularization. Mechanistic validation indicates that Fe-DMY NCPs can inhibit the activation of the Poldip2-Nox4-H2O2 signaling pathway and downregulate vital vascular function indicators such as VCAM-1, HIF-1α, and VEGF. These findings suggest that Fe-DMY NCPs could serve as a safe and effective antioxidant and microangio-protective agent, with the potential as a novel multimeric drug for DR therapy.

ILC3: a case of conflicted identity

Innate lymphoid cells type 3 (ILC3s) are the first line sentinels at the mucous tissues, where they contribute to the homeostatic immune response in a major way. Also, they have been increasingly appreciated as important modulators of chronic inflammatory and autoimmune responses, both locally and systemically. The proper identification of ILC3 is of utmost importance for meaningful studies on their role in immunity. Flow cytometry is the method of choice for the detection and characterization of ILC3. However, the analysis of ILC3-related papers shows inconsistency in ILC3 phenotypic definition, as different inclusion and exclusion markers are used for their identification. Here, we present these discrepancies in the phenotypic characterization of human and mouse ILC3s. We discuss the pros and cons of using various markers for ILC3 identification. Furthermore, we consider the possibilities for the efficient isolation and propagation of ILC3 from different organs and tissues for in-vitro and in-vivo studies. This paper calls upon uniformity in ILC3 definition, isolation, and propagation for the increased possibility of confluent interpretation of ILC3's role in immunity.

Dihydromyricetin Protects Intestinal Barrier Integrity by Promoting IL-22 Expression in ILC3s through the AMPK/SIRT3/STAT3 Signaling Pathway

BACKGROUND

Previous studies indicate that dihydromyricetin (DHM) could alleviate intestinal inflammation and improve intestinal barrier integrity, yet the underlying mechanism remains obscure.

METHODS

C57BL/6 male mice were fed with a control diet, high-fat diet (HFD), or HFD + DHM diet for 12 weeks. The intestinal permeability and expression of intestinal tight junction (TJ) protein were detected to evaluate the effects of DHM on intestinal barrier integrity. The interleukin 22 (IL-22) production of group 3 innate lymphoid cells (ILC3s) in small intestine lamina propria was tested to clarify the effects of DHM on ILC3s. In addition, an MNK3 cell line, which expresses the same transcription factors and cytokines as ILC3, was used to investigate the molecular mechanism under DHM-induced IL-22 expression.

RESULTS

DHM effectively protected HFD-fed mice against intestinal barrier destruction by promoting ILC3 activation and IL-22 secretion, and IL-22 expression increased the expression levels of TJ molecules to protect intestinal barrier integrity. Moreover, DHM increased activation of the AMPK/SIRT3/STAT3 pathway, which in turn promoted IL-22 expression in MNK3 cells.

CONCLUSIONS

DHM improved IL-22 production in ILC3 cells to alleviate HFD-induced intestinal barrier destruction via the AMPK/SIRT3/STAT3 pathway.

Synergistic Beneficial Effects of Resveratrol and Diet on High-Fat Diet-Induced Obesity

Introduction: Despite decades of research, obesity and its related medical complications remain a major health concern globally. Therefore, novel therapeutic strategies are needed to combat obesity and its numerous debilitating complications. Resveratrol (RES) has a potential therapeutic effect in obesity and diabetes by improving oxidative metabolism and insulin signaling. Background and Objectives: The aim of this study was to investigate the effect of RES treatment on weight loss and glucose and fatty acid metabolism. Methods: Obesity was induced in 24 mice by exposure to a high-fat diet (HFD) for 8 weeks. Mice were randomly assigned to one group of either: group 1: control, non-treated low-fat diet (LFD) for 12 weeks (n = 8), group 2: non-treated high-fat diet (HFD) for 12 weeks (n = 8), group 3: RES-treated HFD (HFD + RES) (n = 8), or group 4: RES-treated and switched to LFD (HFD-LFD + RES) (n = 8). HFD + RES mice were first fed an HFD for 8 weeks followed by 4 weeks of RES. The HFD-LFD + RES group was first fed an HFD for 8 weeks and then treated with RES and switched to an LFD for 4 weeks. Results: After 12 weeks, group 2 mice had significantly higher body weights compared to group 1 (23.71 ± 1.95 vs. 47.83 ± 2.27; p < 0.05). Group 4 had a significant decrease in body weight and improvement in glucose tolerance compared to mice in group 2 (71.3 ± 1.17 vs. 46.1 ± 1.82 and 40.9 ± 1.75, respectively; p < 0.05). Skeletal muscles expression of SIRT1, SIRT3, and PGC1α were induced in group 3 and 4 mice compared to group 2 (p < 0.01), with no changes in AMP-activated protein kinase expression levels. Furthermore, combination of RES and diet ameliorated skeletal muscle intermediate lipid accumulation and significantly improved insulin sensitivity and secretion. Conclusions: The results of this study suggest a synergistic beneficial effect of LFD and RES to lower body weight and enhance glucose and fatty acid metabolism.