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Arteriosclerosis, Thrombosis, and... May 2020The immune system plays an important role in obesity-induced adipose tissue inflammation and the resultant metabolic dysfunction, which can lead to hypertension,... (Review)
Review
The immune system plays an important role in obesity-induced adipose tissue inflammation and the resultant metabolic dysfunction, which can lead to hypertension, dyslipidemia, and insulin resistance and their downstream sequelae of type 2 diabetes mellitus and cardiovascular disease. While macrophages are the most abundant immune cell type in adipose tissue, other immune cells are also present, such as B cells, which play important roles in regulating adipose tissue inflammation. This brief review will overview B-cell subsets, describe their localization in various adipose depots and summarize our knowledge about the function of these B-cell subsets in regulating adipose tissue inflammation, obesity-induced metabolic dysfunction and atherosclerosis.
Topics: Adipose Tissue; Animals; Anti-Inflammatory Agents; Atherosclerosis; Autoimmunity; B-Lymphocyte Subsets; Cell Communication; Cytokines; Humans; Immunotherapy; Inflammation Mediators; Panniculitis; Phenotype; Signal Transduction
PubMed: 32131612
DOI: 10.1161/ATVBAHA.119.312467 -
Adipocyte Dec 2023Adipokines are proteins secreted by adipose tissue to regulate glucolipid metabolism and play vital roles in our body. Different adipokines have more than one endocrine...
Adipokines are proteins secreted by adipose tissue to regulate glucolipid metabolism and play vital roles in our body. Different adipokines have more than one endocrine function and be divided into several different categories according to their functions, including adipokines involved in glucolipid metabolism, the inflammatory response, insulin action, activation of brown adipose tissue (BAT) and appetite regulation. Multiple adipokines interact with each other to regulate metabolic processes. Based on the recent progress of adipokine research, this article discusses the role and mechanism of various adipokines in glucolipid metabolism, which may provide new ideas for understanding the pathogenesis and improving the treatment of various metabolic diseases.
Topics: Adipokines; Glucose; Lipid Metabolism; Adipose Tissue; Adipose Tissue, Brown; Energy Metabolism; Leptin
PubMed: 37077042
DOI: 10.1080/21623945.2023.2202976 -
Annual Review of Physiology Feb 2021Adipose tissue depots in distinct anatomical locations mediate key aspects of metabolism, including energy storage, nutrient release, and thermogenesis. Although... (Review)
Review
Adipose tissue depots in distinct anatomical locations mediate key aspects of metabolism, including energy storage, nutrient release, and thermogenesis. Although adipocytes make up more than 90% of adipose tissue volume, they represent less than 50% of its cellular content. Here, I review recent advances in genetic lineage tracing and transcriptomics that reveal the identities of the heterogeneous cell populations constituting mouse and human adipose tissues. In addition to mature adipocytes and their progenitors, these include endothelial and various immune cell types that together orchestrate adipose tissue development and functions. One salient finding is the identification of progenitor subtypes that can modulate adipogenic capacity through paracrine mechanisms. Another is the description of fate trajectories of monocyte/macrophages, which can respond maladaptively to nutritional and thermogenic stimuli, leading to metabolic disease. These studies have generated an extraordinary source of publicly available data that can be leveraged to explore commonalities and differences among experimental models, providing new insights into adipose tissues and their role in metabolic disease.
Topics: Adipocytes; Adipogenesis; Adipose Tissue; Animals; Humans; Thermogenesis
PubMed: 33566675
DOI: 10.1146/annurev-physiol-031620-095446 -
Military Medical Research Jan 2023Obesity is one of the most serious global health problems, with an incidence that increases yearly and coincides with the development of cancer. Adipose tissue... (Review)
Review
Obesity is one of the most serious global health problems, with an incidence that increases yearly and coincides with the development of cancer. Adipose tissue macrophages (ATMs) are particularly important in this context and contribute to linking obesity-related inflammation and tumor progression. However, the functions of ATMs on the progression of obesity-associated cancer remain unclear. In this review, we describe the origins, phenotypes, and functions of ATMs. Subsequently, we summarize the potential mechanisms on the reprogramming of ATMs in the obesity-associated microenvironment, including the direct exchange of dysfunctional metabolites, inordinate cytokines and other signaling mediators, transfer of extracellular vesicle cargo, and variations in the gut microbiota and its metabolites. A better understanding of the properties and functions of ATMs under conditions of obesity will lead to the development of new therapeutic interventions for obesity-related cancer.
Topics: Humans; Adipose Tissue; Obesity; Macrophages; Inflammation; Neoplasms; Tumor Microenvironment
PubMed: 36593475
DOI: 10.1186/s40779-022-00437-5 -
Arteriosclerosis, Thrombosis, and... Nov 2020Atherosclerosis is orchestrated by complex interactions between vascular and inflammatory cells. Traditionally, it has been considered to be an intimal inflammatory... (Review)
Review
Atherosclerosis is orchestrated by complex interactions between vascular and inflammatory cells. Traditionally, it has been considered to be an intimal inflammatory disease, characterized by endothelial dysfunction, inflammatory cell recruitment, lipid oxidation, and foam cell formation. This inside-out signaling paradigm has been accepted as dogma for many years, despite the fact that inflammatory cells are far more prevalent in the adventitia compared with the intima. For decades, the origin of adventitial inflammation in atherosclerosis was unknown. The fact that these inflammatory cells were observed to cluster at the margin of perivascular adipose tissues-a unique and highly inflammatory adipose depot that surrounds most atherosclerosis-prone blood vessels-has stimulated interest in perivascular adipose tissue-mediated outside-in signaling in vascular pathophysiology, including atherosclerosis. The phenotype of perivascular adipocytes underlies the functional characteristics of this depot, including its role in adventitial inflammatory cell recruitment, trafficking to the intima via the vasa vasorum, and atherosclerosis perturbation. This review is focused on emerging concepts pertaining to outside-in signaling in atherosclerosis driven by dysfunctional perivascular adipose tissues during diet-induced obesity and recent strategies for atherosclerosis prediction and prognostication based upon this hypothesis.
Topics: Adipocytes; Adipokines; Adipose Tissue; Animals; Atherosclerosis; Blood Vessels; Cell Communication; Humans; Inflammation; Inflammation Mediators; Plaque, Atherosclerotic; Signal Transduction
PubMed: 32878476
DOI: 10.1161/ATVBAHA.120.312470 -
International Journal of Molecular... Jul 2020Cachexia is a devastating pathology induced by several kinds of diseases, including cancer. The hallmark of cancer cachexia is an extended weight loss mainly due to... (Review)
Review
Cachexia is a devastating pathology induced by several kinds of diseases, including cancer. The hallmark of cancer cachexia is an extended weight loss mainly due to skeletal muscle wasting and fat storage depletion from adipose tissue. The latter exerts key functions for the health of the whole organism, also through the secretion of several adipokines. These hormones induce a plethora of effects in target tissues, ranging from metabolic to differentiating ones. Conversely, the decrease of the circulating level of several adipokines positively correlates with insulin resistance, metabolic syndrome, diabetes, and cardiovascular disease. A lot of findings suggest that cancer cachexia is associated with changed secretion of adipokines by adipose tissue. In agreement, cachectic patients show often altered circulating levels of adipokines. This review reported the findings of adipokines (leptin, adiponectin, resistin, apelin, and visfatin) in cancer cachexia, highlighting that to study in-depth the involvement of these hormones in this pathology could lead to the development of new therapeutic strategies.
Topics: Adipokines; Adipose Tissue; Animals; Cachexia; Humans; Neoplasms
PubMed: 32660156
DOI: 10.3390/ijms21144860 -
Reviews in Endocrine & Metabolic... Feb 2022When normalized to volume, adipose tissue is comprised mainly of large lipid metabolizing and storing cells called adipocytes. Strikingly, the numerical representation... (Review)
Review
When normalized to volume, adipose tissue is comprised mainly of large lipid metabolizing and storing cells called adipocytes. Strikingly, the numerical representation of non-adipocytes, composed of a wide variety of cell types found in the so-called stromal vascular fraction (SVF), outnumber adipocytes by far. Besides its function in energy storage, adipose tissue has emerged as a versatile organ that regulates systemic metabolism and has therefore constituted an attractive target for the treatment of metabolic diseases. Recent high-resolution single cells/nucleus RNA seq data exemplify an intriguingly profound diversity of both adipocytes and SVF cells in all adipose depots, and the current data, while limited, demonstrate the significance of the intra-tissue cell composition in shaping the overall functionality of this tissue. Due to the complexity of adipose tissue, our understanding of the biological relevance of this heterogeneity and plasticity is fractional. Therefore, establishing atlases of adipose tissue cell heterogeneity is the first step towards generating an understanding of these functionalities. In this review, we will describe the current knowledge on adipose tissue cell composition and the heterogeneity of single-cell RNA sequencing, including the technical limitations.
Topics: Adipocytes; Adipose Tissue; Humans
PubMed: 34935088
DOI: 10.1007/s11154-021-09703-8 -
Endocrinology Jan 2022Adipose tissue distribution in the human body is highly heterogeneous, and the relative mass of different depots is differentially associated with metabolic disease... (Review)
Review
Adipose tissue distribution in the human body is highly heterogeneous, and the relative mass of different depots is differentially associated with metabolic disease risk. Distinct functions of adipose depots are mediated by their content of specialized adipocyte subtypes, best exemplified by thermogenic adipocytes found in specific depots. Single-cell transcriptome profiling has been used to define the cellular composition of many tissues and organs, but the large size, buoyancy, and fragility of adipocytes have rendered it challenging to apply these techniques to understand the full complexity of adipocyte subtypes in different depots. Discussed here are strategies that have been recently developed for investigating adipocyte heterogeneity, including single-cell RNA-sequencing profiling of the stromal vascular fraction to identify diverse adipocyte progenitors, and single-nuclei profiling to characterize mature adipocytes. These efforts are yielding a more complete characterization of adipocyte subtypes in different depots, insights into the mechanisms of their development, and perturbations associated with different physiological states such as obesity. A better understanding of the adipocyte subtypes that compose different depots will help explain metabolic disease phenotypes associated with adipose tissue distribution and suggest new strategies for improving metabolic health.
Topics: Adipocytes; Adipogenesis; Adipose Tissue; Adipose Tissue, Beige; Adipose Tissue, Brown; Adipose Tissue, White; Animals; Body Height; Body Mass Index; Body Weight; Cell Differentiation; Cell Separation; Humans; Mice; Single-Cell Analysis; Stem Cells; Stromal Vascular Fraction; Thermogenesis
PubMed: 34223880
DOI: 10.1210/endocr/bqab138 -
Cells Sep 2021The safe removal of apoptotic debris by macrophages-often referred to as efferocytosis-is crucial for maintaining tissue integrity and preventing self-immunity or tissue... (Review)
Review
The safe removal of apoptotic debris by macrophages-often referred to as efferocytosis-is crucial for maintaining tissue integrity and preventing self-immunity or tissue damaging inflammation. Macrophages clear tissues of hazardous materials from dying cells and ultimately adopt a pro-resolving activation state. However, adipocyte apoptosis is an inflammation-generating process, and the removal of apoptotic adipocytes by so-called adipose tissue macrophages triggers a sequence of events that lead to meta-inflammation and obesity-associated metabolic diseases. Signals that allow apoptotic cells to control macrophage immune functions are complex and involve metabolites released by the apoptotic cells and also metabolites produced by the macrophages during the digestion of apoptotic cell contents. This review provides a concise summary of the adipocyte-derived metabolites that potentially control adipose tissue macrophage immune functions and, hence, may induce or alleviate adipose tissue inflammation.
Topics: Adipose Tissue; Animals; Apoptosis; Humans; Inflammation; Macrophages; Phagocytosis; Signal Transduction
PubMed: 34571937
DOI: 10.3390/cells10092288 -
Frontiers in Endocrinology 2021Adipose tissue (AT) is classified based on its location, physiological and functional characteristics. Although there is a clear demarcation of anatomical and molecular... (Review)
Review
Adipose tissue (AT) is classified based on its location, physiological and functional characteristics. Although there is a clear demarcation of anatomical and molecular features specific to white (WAT) and brown adipose tissue (BAT), the factors that uniquely differentiate beige AT (BeAT) remain to be fully elaborated. The ubiquitous presence of different types of AT and the inability to differentiate brown and beige adipocytes because of similar appearance present a challenge when classifying them one way or another. Here we will provide an overview of the latest advances in BeAT, BAT, and WAT identification based on transcript markers described in the literature. The review paper will highlight some of the difficulties these markers pose and will offer new perspectives on possible transcript-specific identification of BeAT. We hope that this will advance the understanding of the biology of different ATs. In addition, concrete strategies to distinguish different types of AT may be relevant to track the efficacy and mechanisms around interventions aimed to improve metabolic health and thwart excessive weight gain.
Topics: Adipose Tissue, Beige; Adipose Tissue, Brown; Adipose Tissue, White; Animals; Biomarkers; Humans; Species Specificity
PubMed: 33776911
DOI: 10.3389/fendo.2021.599134