Single-Cell Landscape and a Macrophage Subset Enhancing Brown Adipocyte Function in Diabetes.

Background: Metabolic dysregulation is a hallmark of type 2 diabetes mellitus (T2DM), in which the abnormalities in brown adipose tissue (BAT) play important roles. However, the cellular composition and function of BAT as well as its pathological significance in diabetes remain incompletely understood. Our objective is to delineate the single-cell landscape of BAT-derived stromal vascular fraction (SVF) and their characteristic alterations in T2DM rats. Methods: T2DM was induced in rats by intraperitoneal injection of low-dose streptozotocin and high-fat diet feeding. Single-cell mRNA sequencing was then performed on BAT samples and compared to normal rats to characterize changes in T2DM rats. Subsequently, the importance of key cell subsets in T2DM was elucidated using various functional studies. Results: Almost all cell types in the BAT-derived SVF of T2DM rats exhibited enhanced inflammatory responses, increased angiogenesis, and disordered glucose and lipid metabolism. The multidirectional differentiation potential of adipose tissue-derived stem cells was also reduced. Moreover, macrophages played a pivotal role in intercellular crosstalk of BAT-derived SVF. A novel Rarres2+macrophage subset promoted the differentiation and metabolic function of brown adipocytes via adipose-immune crosstalk. Conclusion: BAT SVF exhibited strong heterogeneity in cellular composition and function and contributed to T2DM as a significant inflammation source, in which a novel macrophage subset was identified that can promote brown adipocyte function.

Myostain is involved in ginsenoside Rb1-mediated anti-obesity.

CONTEXT: Obesity, one of the major public health problems worldwide, has attracted increasing attention. Ginsenoside Rb1 is the most abundant active component of Panax ginseng C.A.Mey (Araliaceae) and is reported to have beneficial effects on obesity and diabetes. However, the mechanisms by which Rb1 regulates obesity remain to be explored. OBJECTIVE: This paper intends to further explore the mechanism of Rb1 in regulating obesity. MATERIALS AND METHODS: The C57BL/6 obese mice were divided into two groups: the control (CTR) and Rb1. The CTR group [intraperitoneally (ip) administered with saline] and the Rb1 group (ip administered with Rb1, 40 mg/kg/d) were treated daily for four weeks. In vitro, Rb1 (0, 10, 20, 40 µM) was added to differentiated C2C12 cells and Rb1 (0, 20, 40 µM) was added to 3T3-L1 cells. After 24 h, total RNA and protein from C2C12 cells and 3T3-L1 cells were used to detect myostatin (MSTN) and fibronectin type III domain-containing 5 (FNDC5) expression. RESULTS: Rb1 reduced the body weight and adipocyte size. Improved glucose tolerance and increased basic metabolic activity were also found in Rb1 treated mice. MSTN was downregulated in differentiated C2C12 cells, 3T3-L1 cells and adipose tissues upon Rb1 treatment. FNDC5 was increased after Rb1 treatment. However, MSTN overexpression attenuated Rb1-mediated decrease accumulation of lipid droplets in differentiated 3T3-L1 adipocytes. DISCUSSION & CONCLUSIONS: Rb1 may ameliorate obesity in part through the MSTN/FNDC5 signalling pathway. Our results showed that Rb1 can be used as an effective drug in the treatment of human obesity.

MiR-363-5p modulates regulatory T cells through STAT4-HSPB1-Notch1 axis and is associated with the immunological abnormality in Graves' disease.

MiRNAs are a class of small non-coding RNAs with ability to regulate function of Treg cells and are involved in many autoimmune diseases. Our previous study found that miR-363-5p expression was significantly upregulated in peripheral Treg cells of GD patients. Herein, we aimed to investigate its effect and mechanism on Treg cell dysfunction in GD patients. The results showed that miR-363-5p upregulation was significantly associated with the Treg cell dysfunction and inflammatory factors levels in GD patients. Transcriptome sequencing revealed that 883 genes were significantly regulated by miR-363-5p in Treg cells. These genes with significant differential expression were primarily involved in lymphocyte differentiation, immunity, as well as Notch1 and various interleukin signalling pathways. Moreover, miR-363-5p can regulate HSPB1 and Notch1 through the target gene STAT4, thereby regulating Notch1 signalling pathway and inhibiting Treg cells. The effects of miR-363-5p on Treg cell function and STAT4-HSPB1-Notch1 axis were also verified in GD patients. In conclusion, our results indicated that miR-363 could inhibit the proliferation, differentiation and function of Treg cells by regulating the STAT4-HSPB1-Notch1 axis through target gene STAT4. MiR-363-5p may play an important role in Treg cell dysfunction and immune tolerance abnormalities in GD patients.

MiR-381-3p redistributes between cytosol and mitochondria and aggravates endothelial cell injury induced by reactive oxygen species.

MicroRNAs (miRNAs) are reported to play pivotal roles in reactive oxygen species (ROS)-induced endothelial cell injury and several studies have demonstrated the miRNA distribution in the mitochondria of various cells. However, very little is known about its changes and roles in ROS-induced endothelial cell injury. In the present study, we systematically revealed the distribution changes of miRNAs in mitochondria during ROS-induced endothelial cell injury and found that H2O2 obviously reduced the mitochondrial distribution of many miRNAs without affecting their expression levels in the whole endothelial cells. Most of these miRNAs showing reduced mitochondrial distribution were potentially involved in ROS-induced endothelial cell injury. MiR-381-3p was a typical representative of these miRNAs and its redistribution between mitochondria and cytosol regulated the network consisting of downstream molecules (P53, P21, CCND1, and MYC) by inhibiting its target genes (LRP6 and NFIA) to promote apoptosis and inhibit proliferation in endothelial cells. Our findings highlight the significance of redistribution of miRNAs between mitochondria and cytosol and improve our understanding of miRNA function regulation.

Gut Dysbiosis Contributes to the Imbalance of Treg and Th17 Cells in Graves' Disease Patients by Propionic Acid.

BACKGROUND: Graves' disease (GD) is a typical organ-specific autoimmune disease. Intestinal flora plays a pivotal role in immune homeostasis and autoimmune disease development. However, the association and mechanism between intestinal flora and GD remain elusive. OBJECTIVE: To investigate the association and mechanism between intestinal flora and GD. METHODS: We recruited 58 initially untreated GD patients and 63 healthy individuals in the study. The composition and metabolic characteristics of the intestinal flora in GD patients and the causal relationship between intestinal flora and GD pathogenesis were assessed using 16S rRNA gene sequencing, targeted/untargeted metabolomics, and fecal microbiota transplantation. RESULTS: The composition, metabolism, and inter-relationships of the intestinal flora were also changed, particularly the significantly reduced short-chain fatty acid (SCFA)-producing bacteria and SCFAs. The YCH46 strain of Bacteroides fragilis could produce propionic acid and increase Treg cell numbers while decreasing Th17 cell numbers. Transplanting the intestinal flora of GD patients significantly increased GD incidence in the GD mouse model. Additionally, there were 3 intestinal bacteria genera (Bacteroides, Alistipes, Prevotella) could distinguish GD patients from healthy individuals with 85% accuracy. CONCLUSIONS: Gut dysbiosis contributes to a Treg/Th17 imbalance through the pathway regulated by propionic acid and promotes the occurrence of GD, together with other pathogenic factors. Bacteroides, Alistipes, and Prevotella have great potential to serve as adjunct markers for GD diagnosis. This study provided valuable clues for improving immune dysfunction of GD patients using B. fragilis and illuminated the prospects of microecological therapy for GD as an adjunct treatment.

Intestinal Flora Modulates Blood Pressure by Regulating the Synthesis of Intestinal-Derived Corticosterone in High Salt-Induced Hypertension.

RATIONALE: High-salt diet is one of the most important risk factors for hypertension. Intestinal flora has been reported to be associated with high salt-induced hypertension (hSIH). However, the detailed roles of intestinal flora in hSIH pathogenesis have not yet been fully elucidated. OBJECTIVE: To reveal the roles and mechanisms of intestinal flora in hSIH development. METHODS AND RESULTS: The abovementioned issues were investigated using various techniques including 16S rRNA gene sequencing, untargeted metabolomics, selective bacterial culture, and fecal microbiota transplantation. We found that high-salt diet induced hypertension in Wistar rats. The fecal microbiota of healthy rats could dramatically lower blood pressure (BP) of hypertensive rats, whereas the fecal microbiota of hSIH rats had opposite effects. The composition, metabolism, and interrelationship of intestinal flora in hSIH rats were considerably reshaped, including the increased corticosterone level and reduced Bacteroides and arachidonic acid levels, which tightly correlated with BP. The serum corticosterone level was also significantly increased in rats with hSIH. Furthermore, the above abnormalities were confirmed in patients with hypertension. The intestinal Bacteroides fragilis could inhibit the production of intestinal-derived corticosterone induced by high-salt diet through its metabolite arachidonic acid. CONCLUSIONS: hSIH could be transferred by fecal microbiota transplantation, indicating the pivotal roles of intestinal flora in hSIH development. High-salt diet reduced the levels of B fragilis and arachidonic acid in the intestine, which increased intestinal-derived corticosterone production and corticosterone levels in serum and intestine, thereby promoting BP elevation. This study revealed a novel mechanism different from inflammation/immunity by which intestinal flora regulated BP, namely intestinal flora could modulate BP by affecting steroid hormone levels. These findings enriched the understanding of the function of intestinal flora and its effects on hypertension.

Comprehensive Glycomic Analysis Reveals That Human Serum Albumin Glycation Specifically Affects the Pharmacokinetics and Efficacy of Different Anticoagulant Drugs in Diabetes.

Long-term hyperglycemia in patients with diabetes leads to human serum albumin (HSA) glycation, which may impair HSA function as a transport protein and affect the therapeutic efficacy of anticoagulants in patients with diabetes. In this study, a novel mass spectrometry approach was developed to reveal the differences in the profiles of HSA glycation sites between patients with diabetes and healthy subjects. K199 was the glycation site most significantly changed in patients with diabetes, contributing to different interactions of glycated HSA and normal HSA with two types of anticoagulant drugs, heparin and warfarin. An in vitro experiment showed that the binding affinity to warfarin became stronger when HSA was glycated, while HSA binding to heparin was not significantly influenced by glycation. A pharmacokinetic study showed a decreased level of free warfarin in the plasma of diabetic rats. A preliminary retrospective clinical study also revealed that there was a statistically significant difference in the anticoagulant efficacy between patients with diabetes and patients without diabetes who had been treated with warfarin. Our work suggests that larger studies are needed to provide additional specific guidance for patients with diabetes when they are administered anticoagulant drugs or drugs for treating other chronic diseases.

A series of TA-based and zero-background vectors for plant functional genomics.

With the sequencing of genomes from many organisms now complete and the development of high-throughput sequencing, life science research has entered the functional post-genome era. Therefore, deciphering the function of genes and how they interact is in greater demand. To study an unknown gene, the basic methods are either overexpression or gene knockout by creating transgenic plants, and gene construction is usually the first step. Although traditional cloning techniques using restriction enzymes or a site-specific recombination system (Gateway or Clontech cloning technology) are highly useful for efficiently transferring DNA fragments into destination plasmids, the process is time consuming and expensive. To facilitate the procedure of gene construction, we designed a TA-based cloning system in which only one step was needed to subclone a DNA fragment into vectors. Such a cloning system was developed from the pGreen binary vector, which has a minimal size and facilitates construction manipulation, combined with the negative selection marker gene ccdB, which has the advantages of eliminating the self-ligation background and directly enabling high-efficiency TA cloning technology. We previously developed a set of transient and stable transformation vectors for constitutive gene expression, gene silencing, protein tagging, subcellular localization analysis and promoter activity detection. Our results show that such a system is highly efficient and serves as a high-throughput platform for transient or stable transformation in plants for functional genome research.