PPARγ activation improves the microenvironment of perivascular adipose tissue and attenuates aortic stiffening in obesity

Cross-talks between perivascular adipose tissue and neighbors: multifaceted nature of nereids

Perivascular adipose tissue (PVAT) is a unique fat depot surrounding blood vessels and plays a vital role in the progression of vascular remodeling and dysfunction. PVAT exhibits remarkable differences in structure, phenotype, origin, and secretome across anatomical locations. The proximity of PVAT to neighboring vascular beds favors a niche for bidirectional communication between adipocytes and vascular smooth muscle cells, endothelial cells, and immune cells. In this review, we update our understanding of PVAT's regional differences and provide a comprehensive exploration of how these differences impact cross-talks between PVAT and the vascular wall. Different PVAT depots show different degrees of vasoprotective function and resilience to pathological changes such as obesity and vasculopathies, shaping multifaceted interactions between PVAT depots and adjacent vasculatures. The depot-specific resilience may lead to innovative strategies to manage cardiometabolic disorders.

Threonine Deficiency Increases Triglyceride Deposition in Primary Duck Hepatocytes by Reducing STAT3 Phosphorylation

Liver lipid metabolism disruption significantly contributes to excessive fat buildup in waterfowl. Research suggests that the supplementation of Threonine (Thr) in the diet can improve liver lipid metabolism disorder, while Thr deficiency can lead to such metabolic disorders in the liver. The mechanisms through which Thr regulates lipid metabolism remain unclear. STAT3 (signal transducer and activator of transcription 3), a crucial transcription factor in the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway, participates in various biological processes, including lipid and energy metabolism. This research investigates the potential involvement of STAT3 in the increased lipid storage seen in primary duck hepatocytes as a result of a lack of Thr. Using small interfering RNA and Stattic, a specific STAT3 phosphorylation inhibitor, we explored the impact of STAT3 expression patterns on Thr-regulated lipid synthesis metabolism in hepatocytes. Through transcriptome sequencing, we uncovered pathways related to lipid synthesis and metabolism jointly regulated by Thr and STAT3. The results showed that Thr deficiency increases lipid deposition in primary duck hepatocytes (p < 0.01). The decrease in protein and phosphorylation levels of STAT3 directly caused this deposition (p < 0.01). Transcriptomic analysis revealed that Thr deficiency and STAT3 knockdown jointly altered the mRNA expression levels of pathways related to long-chain fatty acid synthesis and energy metabolism (p < 0.05). Thr deficiency, through mediating STAT3 inactivation, upregulated ELOVL7, PPARG, MMP1, MMP13, and TIMP4 mRNA levels, and downregulated PTGS2 mRNA levels (p < 0.01). In summary, these results suggest that Thr deficiency promotes lipid synthesis, reduces lipid breakdown, and leads to lipid metabolism disorders and triglyceride deposition by downregulating STAT3 activity in primary duck hepatocytes.

Migrasomes from adipose derived stem cells enrich CXCL12 to recruit stem cells via CXCR4/RhoA for a positive feedback loop mediating soft tissue regeneration

BACKGROUND

Adipose-derived stem cells (ASCs) represent the most advantageous choice for soft tissue regeneration. Studies proved the recruitment of ASCs post tissue injury was mediated by chemokine CXCL12, but the mechanism by which CXCL12 is generated after tissue injury remains unclear. Migrasomes are newly discovered membrane-bound organelles that could deliver CXCL12 spatially and temporally in vivo. In this study, we sought to investigate whether migrasomes participate ASC-mediated tissue regeneration.

METHODS

Discrepant and asymmetrical soft tissue regeneration mice model were established, in which HE staining, immunofluorescent staining, western blot and qPCR were conducted to confirm the role of CXCL12 and migrasomes in ASC-mediated tissue regeneration. Characterization of ASC-derived migrasomes were carried out by confocal microscopy, scanning electron microscopy, transmission electron microscopy as well as western blot analysis. The function and mechanism of migrasomes were further testified by assisting tissue regeneration with isolated migrasomes in vivo and by in vitro transwell combined with co-culture system.

RESULTS

Here, we show for the first time that migrasomes participate in soft tissue regeneration. ASCs generate migrasomes enriched with CXCL12 to mediate tissue regeneration. Migrasomes from ASCs could promote stem cells migration by activating CXCR4/RhoA signaling in vivo and in vitro. Chemoattracted ASCs facilitate regeneration, as demonstrated by the upregulation of an adipogenesis-associated protein. This positive feed-back-loop creates a favorable microenvironment for soft tissue regeneration. Thus, migrasomes represent a new therapeutic target for ASC-mediated tissue regeneration.

CONCLUSIONS

Our findings reveal a previously unknown function of ASCs in mediating tissue regeneration by generating migrasomes. The ASC-derived migrasomes can restore tissue regeneration by recruiting stem cells, which highlighting the potential application of ASC-derived migrasomes in regenerative medicine.

Perivascular fat tissue and vascular aging: A sword and a shield

The understanding of the function of perivascular adipose tissue (PVAT) in vascular aging has significantly changed due to the increasing amount of information regarding its biology. Adipose tissue surrounding blood vessels is increasingly recognized as a key regulator of vascular disorders. It has significant endocrine and paracrine effects on the vasculature and is mediated by the production of a variety of bioactive chemicals. It also participates in a number of pathological regulatory processes, including oxidative stress, immunological inflammation, lipid metabolism, vasoconstriction, and dilation. Mechanisms of homeostasis and interactions between cells at the local level tightly regulate the function and secretory repertoire of PVAT, which can become dysregulated during vascular aging. The PVAT secretion group changes from being reducing inflammation and lowering cholesterol to increasing inflammation and increasing cholesterol in response to systemic or local inflammation and insulin resistance. In addition, the interaction between the PVAT and the vasculature is reciprocal, and the biological processes of PVAT are directly influenced by the pertinent indicators of vascular aging. The architectural and biological traits of PVAT, the molecular mechanism of crosstalk between PVAT and vascular aging, and the clinical correlation of vascular age-related disorders are all summarized in this review. In addition, this paper aims to elucidate and evaluate the potential benefits of therapeutically targeting PVAT in the context of mitigating vascular aging. Furthermore, it will discuss the latest advancements in technology used for targeting PVAT.

A cell atlas of thoracic aortic perivascular adipose tissue: a focus on mechanotransducers

Perivascular adipose tissue (PVAT) is increasingly recognized for its function in mechanotransduction. However, major gaps remain in our understanding of the cells present in PVAT, as well as how different cells contribute to mechanotransduction. We hypothesized that snRNA-seq would reveal the expression of mechanotransducers, and test one (PIEZO1) to illustrate the expression and functional agreement between single-nuclei RNA sequencing (snRNA-seq) and physiological measurements. To contrast two brown tissues, subscapular brown adipose tissue (BAT) was also examined. We used snRNA-seq of the thoracic aorta PVAT (taPVAT) and BAT from male Dahl salt-sensitive (Dahl SS) rats to investigate cell-specific expression mechanotransducers. Localization and function of the mechanostransducer PIEZO1 were further examined using immunohistochemistry (IHC) and RNAscope, as well as pharmacological antagonism. Approximately 30,000 nuclei from taPVAT and BAT each were characterized by snRNA-seq, identifying eight major cell types expected and one unexpected (nuclei with oligodendrocyte marker genes). Cell-specific differential gene expression analysis between taPVAT and BAT identified up to 511 genes (adipocytes) with many (≥20%) being unique to individual cell types. Piezo1 was the most highly, widely expressed mechanotransducer. The presence of PIEZO1 in the PVAT but not the adventitia was confirmed by RNAscope and IHC in male and female rats. Importantly, antagonism of PIEZO1 by GsMTX4 impaired the PVAT's ability to hold tension. Collectively, the cell compositions of taPVAT and BAT are highly similar, and PIEZO1 is likely a mechanotransducer in taPVAT.NEW & NOTEWORTHY This study describes the atlas of cells in the thoracic aorta perivascular adipose tissue (taPVAT) of the Dahl-SS rat, an important hypertension model. We show that mechanotransducers are widely expressed in these cells. Moreover, PIEZO1 expression is shown to be restricted to the taPVAT and is functionally implicated in stress relaxation. These data will serve as the foundation for future studies investigating the role of taPVAT in this model of hypertensive disease.

A Cell Atlas of Thoracic Aortic Perivascular Adipose Tissue: a focus on mechanotransducers

Perivascular adipose tissue (PVAT) is increasingly recognized for its function in mechanotransduction. To examine the cell-specificity of recognized mechanotransducers we used single nuclei RNA sequencing (snRNAseq) of the thoracic aorta PVAT (taPVAT) from male Dahl SS rats compared to subscapular brown adipose tissue (BAT). Approximately 30,000 nuclei from taPVAT and BAT each were characterized by snRNAseq, identifying 8 major cell types expected and one unexpected (nuclei with oligodendrocyte marker genes). Cell-specific differential gene expression analysis between taPVAT and BAT identified up to 511 genes (adipocytes) with many (≥20%) being unique to individual cell types. Piezo1 was the most highly, widely expressed mechanotransducer. Presence of PIEZO1 in the PVAT was confirmed by RNAscope® and IHC; antagonism of PIEZO1 impaired the PVAT's ability to hold tension. Collectively, the cell compositions of taPVAT and BAT are highly similar, and PIEZO1 is likely a mechanotransducer in taPVAT.

Assessing Abdominal Aortic Aneurysm Progression by Using Perivascular Adipose Tissue Attenuation on Computed Tomography Angiography

OBJECTIVE

Recent studies have highlighted the active and potential role of perivascular adipose tissue (PVAT) in atherosclerosis and aneurysm progression, respectively. This study explored the link between PVAT attenuation and abdominal aortic aneurysm (AAA) progression using computed tomography angiography (CTA).

MATERIALS AND METHODS

This multicenter retrospective study analyzed patients with AAA who underwent CTA at baseline and follow-up between March 2015 and July 2022. The following parameters were obtained: maximum diameter and total volume of the AAA, presence or absence of intraluminal thrombus (ILT), maximum diameter and volume of the ILT, and PVAT attenuation of the aortic aneurysm at baseline CTA. PVAT attenuation was divided into high (> -73.4 Hounsfield units [HU]) and low (≤ -73.4 HU). Patients who had or did not have AAA progression during the follow-up, defined as an increase in the aneurysm volume > 10 mL from baseline, were identified. Kaplan-Meier and multivariable Cox regression analyses were used to investigate the association between PVAT attenuation and AAA progression.

RESULTS

Our study included 167 participants (148 males; median age: 70.0 years; interquartile range: 63.0-76.0 years), of which 145 (86.8%) were diagnosed with AAA accompanied by ILT. Over a median period of 11.3 months (range: 6.0-85.0 months), AAA progression was observed in 67 patients (40.1%). Multivariable Cox regression analysis indicated that high baseline PVAT attenuation (adjusted hazard ratio [aHR] = 2.23; 95% confidence interval [CI], 1.16-4.32; P = 0.017) was independently associated with AAA progression. This association was demonstrated within the patients of AAA with ILT subcohort, where a high baseline PVAT attenuation (aHR = 2.23; 95% CI, 1.08-4.60; P = 0.030) was consistently independently associated with AAA progression.

CONCLUSION

Elevated PVAT attenuation is independently associated with AAA progression, including patients of AAA with ILT, suggesting the potential of PVAT attenuation as a predictive imaging marker for AAA expansion.

Perivascular Adipose Tissue Oxidative Stress in Obesity

Perivascular adipose tissue (PVAT) adheres to most systemic blood vessels in the body. Healthy PVAT exerts anticontractile effects on blood vessels and further protects against cardiovascular and metabolic diseases. Healthy PVAT regulates vascular homeostasis via secreting an array of adipokine, hormones, and growth factors. Normally, homeostatic reactive oxygen species (ROS) in PVAT act as secondary messengers in various signalling pathways and contribute to vascular tone regulation. Excessive ROS are eliminated by the antioxidant defence system in PVAT. Oxidative stress occurs when the production of ROS exceeds the endogenous antioxidant defence, leading to a redox imbalance. Oxidative stress is a pivotal pathophysiological process in cardiovascular and metabolic complications. In obesity, PVAT becomes dysfunctional and exerts detrimental effects on the blood vessels. Therefore, redox balance in PVAT emerges as a potential pathophysiological mechanism underlying obesity-induced cardiovascular diseases. In this review, we summarise new findings describing different ROS, the major sources of ROS and antioxidant defence in PVAT, as well as potential pharmacological intervention of PVAT oxidative stress in obesity.

Peroxisome proliferator-activated receptor-γ as the gatekeeper of tight junction in Clostridioides difficile infection

Clostridioides difficile is a major causative pathogen of nosocomial antibiotic-associated diarrhea and severe colitis. Despite the use of vancomycin and fidaxomicin as standard drugs for the treatment of C. difficile infection (CDI), clinical relapse rates remain high. Therefore, new alternative therapeutics to treat CDI are urgently required. The nuclear receptor, peroxisome proliferator-activated receptor-γ (PPAR-γ), is mainly expressed in the adipose tissue and modulates lipid metabolism and insulin sensitization. Previous studies have shown that PPAR-γ is highly expressed in colonic tissues and regulates tight junction function in epithelial cells. However, the role of PPAR-γ in CDI pathogenesis remains unclear. In this study, we used a mouse model of CDI and found that both expression levels of PPAR-γ and the tight junction protein, occludin, were decreased in colonic tissues. Furthermore, to investigate the role of PPAR-γ in CDI, we used PPAR-γ defective mice and found that intestinal permeability and bacterial dissemination in these mice were significantly higher than those in wild-type mice during CDI. Administration of the PPAR-γ agonist, pioglitazone, to activate PPAR-γ activity improved the phenotypes of CDI, including bodyweight loss, inflammation, and intestinal integrity. Taken together, these results demonstrate that PPAR-γ is a potential therapeutic target in CDI, as it modulates colonic inflammation and integrity.

Pulmonary hypertension: Linking inflammation and pulmonary arterial stiffening

Pulmonary hypertension (PH) is a progressive disease that arises from multiple etiologies and ultimately leads to right heart failure as the predominant cause of morbidity and mortality. In patients, distinct inflammatory responses are a prominent feature in different types of PH, and various immunomodulatory interventions have been shown to modulate disease development and progression in animal models. Specifically, PH-associated inflammation comprises infiltration of both innate and adaptive immune cells into the vascular wall of the pulmonary vasculature—specifically in pulmonary vascular lesions—as well as increased levels of cytokines and chemokines in circulating blood and in the perivascular tissue of pulmonary arteries (PAs). Previous studies suggest that altered hemodynamic forces cause lung endothelial dysfunction and, in turn, adherence of immune cells and release of inflammatory mediators, while the resulting perivascular inflammation, in turn, promotes vascular remodeling and the progression of PH. As such, a vicious cycle of endothelial activation, inflammation, and vascular remodeling may develop and drive the disease process. PA stiffening constitutes an emerging research area in PH, with relevance in PH diagnostics, prognostics, and as a therapeutic target. With respect to its prognostic value, PA stiffness rivals the well-established measurement of pulmonary vascular resistance as a predictor of disease outcome. Vascular remodeling of the arterial extracellular matrix (ECM) as well as vascular calcification, smooth muscle cell stiffening, vascular wall thickening, and tissue fibrosis contribute to PA stiffening. While associations between inflammation and vascular stiffening are well-established in systemic vascular diseases such as atherosclerosis or the vascular manifestations of systemic sclerosis, a similar connection between inflammatory processes and PA stiffening has so far not been addressed in the context of PH. In this review, we discuss potential links between inflammation and PA stiffening with a specific focus on vascular calcification and ECM remodeling in PH.

Diallyl Trisulfide Prevents Adipogenesis and Lipogenesis by Regulating the Transcriptional Activation Function of KLF15 on PPARγ to Ameliorate Obesity

SCOPE

Diallyl trisulfide (DATS) is a bioactive compound in garlic. The anti-obesity effect of garlic oil has been reported, but the role and mechanism of DATS in preventing obesity remain to be explored.

METHODS AND RESULTS

We performed studies with high-fat-diet-induced obese mice and 3T3-L1 adipocytes. The results showed that DATS significantly reduced lipid accumulation and repaired disordered metabolism in vivo by restraining adipogenesis and lipogenesis, and promoting lipolysis and fatty acid oxidation in white adipose tissue. In cells, DATS played different roles at different stages of adipocyte differentiation. Notably, DATS reduced lipid accumulation mainly by inhibiting adipogenesis and lipogenesis at the late stage. KLF15 was knocked down in 3T3-L1 cells, which eliminated the inhibitory effect of DATS on adipogenesis and lipogenesis. The dual-luciferase reporter and ChIP assays indicated that DATS could inhibit the transcriptional activation function of KLF15 on PPARγ by inhibiting the binding of KLF15 to PPARγ promoter. The function comparison of structural analogs and the intervention of dithiothreitol showed that disulfide bond was crucial for DATS to work.

CONCLUSION

DATS prevents obesity by regulating the transcriptional activation function of KLF15 on PPARγ. This article is protected by copyright. All rights reserved.

The role of adipose tissue-derived hydrogen sulfide in inhibiting atherosclerosis

Hydrogen sulfide (H₂S) is the third gaseous signaling molecule discovered in the body after NO and CO and plays an important organismal protective role in various diseases. Within adipose tissue, related catalytic enzymes (cystathionine-β-synthetase, cystathionine-γ-lyase, and 3-mercaptopyruvate transsulfuration enzyme) can produce and release endogenous H₂S. Atherosclerosis (As) is a pathological change in arterial vessels that is closely related to abnormal glucose and lipid metabolism and a chronic inflammatory response. Previous studies have shown that H₂S can act on the cardiovascular system, exerting effects such as improving disorders of glycolipid metabolism, alleviating insulin resistance, protecting the function of vascular endothelial cells, inhibiting vascular smooth muscle cell proliferation and migration, regulating vascular tone, inhibiting the inflammatory response, and antagonizing the occurrence and development of As.

Ginsenoside compound K inhibits obesity-induced insulin resistance by regulation of macrophage recruitment and polarization via activating PPARγ

Obesity disrupts the immune system of adipose tissue, and the activation of its macrophages constantly infiltrating adipose tissue is a crucial cause of insulin resistance induced by obesity. We previously reported for the first time in vitro that the antidiabetic effect of CK may be through the inhibition of macrophage activation and we further explored the specific mechanism in vivo. In order to clarify it, the C57BL/6J mice were fed with a high fat diet and then administered with CK orally. The related biochemical indices were detected, the inflammatory factors in serum and tissues were measured, and the related protein expression levels in insulin pathways and inflammatory signaling pathways were observed. The results showed that CK could dose-dependently reduce macrophage M1-type inflammatory factor expression in serum and adipose tissue, improve insulin resistance and glucose tolerance effectively, upregulate PPARγ expression and block TLR4/TRAF6/TAK1/NF-κB activation in obese mice. In addition, CK promoted the expression of IRS1/PI3K/AKT. Furthermore, our study showed that ginsenoside CK could improve insulin resistance by reducing inflammation through the PPARγ/NF-κB signaling pathway, which implies that ginsenoside CK may be an effective agent against obesity or early diabetes.

Exploring the Relationship of Perivascular Adipose Tissue Inflammation and the Development of Vascular Pathologies

Initially thought to only provide mechanical support for the underlying blood vessels, perivascular adipose tissue (PVAT) has now emerged as a regulator of vascular function. A healthy PVAT exerts anticontractile and anti-inflammatory actions on the underlying vasculature via the release of adipocytokines such as adiponectin, nitric oxide, and omentin. However, dysfunctional PVAT produces more proinflammatory adipocytokines such as leptin, resistin, interleukin- (IL-) 6, IL-1β, and tumor necrosis factor-alpha, thus inducing an inflammatory response that contributes to the pathogenesis of vascular diseases. In this review, current knowledge on the role of PVAT inflammation in the development of vascular pathologies such as atherosclerosis and hypertension was discussed.

Novel Genes Potentially Involved in Fibroblasts of Diabetic Wound

Fibroblasts are the essential cell type of skin, highly involved in the wound regeneration process. In this study, we sought to screen out the novel genes which act important roles in diabetic fibroblasts through bioinformatic methods. A total of 811 and 490 differentially expressed genes (DEGs) between diabetic and normal fibroblasts were screened out in GSE49566 and GSE78891, respectively. Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways involved in type 2 diabetes were retrieved from miRWalk. Consequently, the integrated bioinformatic analyses revealed the shared KEGG pathways between DEG-identified and diabetes-related pathways were functionally enriched in the MAPK signaling pathway, and the MAPKAPK3, HSPA2, TGFBR1, and p53 signaling pathways were involved. Finally, ETV4 and NPE2 were identified as the targeted transcript factors of MAPKAPK3, HSPA2, and TGFBR1. Our findings may throw novel sight in elucidating the molecular mechanisms of fibroblast pathologies in patients with diabetic wounds and targeting new factors to advance diabetic wound treatment in clinic.

Relationships Between Perivascular Adipose Tissue and Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) are typically asymptomatic, and there is a high mortality rate associated with aneurysm rupture. AAA pathogenesis involves extracellular matrix degradation, vascular smooth muscle cell phenotype switching, inflammation, and oxidative stress. There is increasing evidence of excessive adipocyte accumulation in ruptured AAA walls. These excessive numbers of adipocytes in the vascular wall have been closely linked with AAA progression. Perivascular adipose tissue (PVAT), a unique type of adipose tissue, can be involved in adipocyte accumulation in the AAA wall. PVAT produces various chemokines and adipocytokines around vessels to maintain vascular homeostasis through paracrine and autocrine mechanisms in normal physiological conditions. Nevertheless, PVAT loses its normal function and promotes the progression of vascular diseases in pathological conditions. There is evidence of significantly reduced AAA diameter in vessel walls of removed PVAT. There is a need to highlight the critical roles of cytokines, cells, and microRNA derived from PVAT in the regulation of AAA development. PVAT may constitute an important therapeutic target for the prevention and treatment of AAAs. In this review, we discuss the relationship between PVAT and AAA development; we also highlight the potential for PVAT-derived factors to serve as a therapeutic target in the treatment of AAAs.