Gut microbiota-mediated ursodeoxycholic acids regulate the inflammation of microglia through TGR5 signaling after MCAO.

Ischemic stroke has been demonstrated to cause an imbalance of gut microbiota. However, the change in gut microbiota-mediated bile acids (BAs) metabolites remains unclear. Here, we observed a decrease in gut microbiota-mediated BAs, especially ursodeoxycholic acid (UDCA), in the serum of stroke patients as well as in the intestine, serum and brain of stroke mice. Restoration of UDCA could decrease the area of infarction and improve the neurological function and cognitive function in mice in association with inhibition of NLRP3-related pro-inflammatory cytokines through TGR5/PKA pathway. Furthermore, knocking out TGR5 and inhibiting PKA activity reduce the protective effect of UDCA. Taken together, our results suggest that microbiota-mediated UDCA plays an important role in alleviating inflammatory responses and might be a promising therapeutic target in ischemic stroke.

Microbial metagenomic shifts in children with acute lymphoblastic leukaemia during induction therapy and predictive biomarkers for infection.

BACKGROUND: Emerging evidence has indicated a link between the gut microbiota and acute lymphoblastic leukaemia (ALL). However, the acute changes in gut microbiota during chemotherapy and the predictive value of baseline gut microbiota in infectious complication remain largely unknown. METHODS: Faecal samples (n = 126) from children with ALL (n = 49) undergoing induction chemotherapy were collected at three timepoints, i.e., initiation of chemotherapy (baseline, T0), 7 days (T1) and 33 days (T2) after initiation of chemotherapy. Gut microbiome profile was performed via metagenomic shotgun sequencing. The bioBakery3 pipeline (Kneaddata, Metaphlan 3 and HUMAnN) was performed to assign taxonomy and functional annotations. Gut microbiome at T0 were used to predict infection during chemotherapy. RESULTS: The microbial diversities and composition changed significantly during chemotherapy, with Escherichia coli, Klebsiella pneumoniae and Bifidobacterium longum being the most prominent species. The microbial metabolic pathways were also significantly altered during chemotherapy, including the pathway of pyruvate fermentation to acetate and lactate, and assimilatory sulfate reduction pathway. The receiver operating characteristic (ROC) models based on Bifidobacterium longum at T0 could predict infectious complications during the first month of chemotherapy with the area under the curve (AUC) of 0.720. CONCLUSIONS: Our study provides new insights into the acute changes in microbial and functional characteristics in children with ALL during chemotherapy. The baseline gut microbiota could be potential biomarkers for infections during chemotherapy. TRIAL REGISTRATION: The study was approved by the Ethics Committee of Zhujiang Hospital, Southern Medical University (2021-KY-171-01) and registered on http://www.chictr.org.cn (ChiCTR2200065406, Registration Date: November 4, 2022).

Design, Synthesis, and Biological Evaluation of Novel Quinazoline Derivatives Possessing a Trifluoromethyl Moiety as Potential Antitumor Agents.

A novel series of trifluoromethyl-containing quinazoline derivatives with a variety of functional groups was designed, synthesized, and tested for their antitumor activity by following a pharmacophore hybridization strategy. Most of the 20 compounds displayed moderate to excellent antiproliferative activity against five different cell lines (PC3, LNCaP, K562, HeLa, and A549). After three rounds of screening and structural optimization, compound 10 b was identified as the most potent one, with IC50 values of 3.02, 3.45, and 3.98 µM against PC3, LNCaP, and K562 cells, respectively, which were comparable to the effect of the positive control gefitinib. To further explore the mechanism of action of 10 b against cancer, experiments focusing on apoptosis induction, cell cycle arrest, and cell migration assay were conducted. The results showed that 10 b was able to induce apoptosis and prevent tumor cell migration, but had no effect on the cell cycle of tumor cells.

Transferring and Retaining of Different Polyaniline Nanofeatures via Electrophoretic Deposition for Enhanced Sensing Performance.

Nanofeatured polyaniline (PANI) electrodes have demonstrated impressive sensing performance due to the enhanced electrolyte diffusion and ion transport. However, the retaining of these nanostructures on substrates via electrophoretic deposition (EPD) faces an insurmountable challenge from the involved dedoping process. Here, camphorsulfonic acid is utilized with high steric effects to dope PANI (PANI-CSA) that can be directly used EPD without involving a dedoping process. Five different nanofeatures (sea cucumber-like, nanofiber, amorphous, nanotube, and nanorod) are synthesized, and they have been all successfully transferred onto indium tin oxide substrate in a formic acid/acetonitrile system, namely a morphology memory effect. The mechanism of retaining these nanofeatures is revealed, which is realized via the processes of dissolution of PANI-CSA, codoping and solvation, and reassembly of basic units into the original nanofeature. The enhanced protonation level by the codoping of formic acid and solvation of acetonitrile plays the key role in retaining these nanofeatures. This method is also applicable to transfer PANI/gold nanorod composites (PANI-CSA/AuNRs). The PANI-CSA/AuNRs electrode as an ascorbic acid sensor has shown an excellent sensing performance with a sensitivity up to 872.7 µA mm-1 cm-2 and a detection limit of as low as 0.18 × 10-6 m.

Gut microbiota is causally associated with poststroke cognitive impairment through lipopolysaccharide and butyrate.

BACKGROUND: Poststroke cognitive impairment (PSCI) is prevalent in stroke patients. The etiology of PSCI remains largely unknown. We previously found that stroke induces gut microbiota dysbiosis which affects brain injury. Hereby, we aimed to investigate whether the gut microbiota contributes to the pathogenesis of PSCI. METHODS: 83 stroke patients were recruited and their cognitive function were measured by Montreal Cognitive Assessment (MoCA) scores 3 months after stroke onset. The peripheral inflammatory factor levels and gut microbiota compositions of the patients were analyzed. Fecal microbiota transplantation from patients to stroke mice was performed to examine the causal relationship between the gut microbiota and PSCI. The cognitive function of mice was evaluated by Morris water maze test. RESULTS: 34 and 49 stroke patients were classified as PSCI and non-PSCI, respectively. Compared with non-PSCI patients, PSCI patients showed significantly higher levels of gut Enterobacteriaceae, lipopolysaccharide (LPS) and peripheral inflammation markers. Consistently, stroke mice that received microbiota from PSCI patients (PSCI mice) presented a higher level of Enterobacteriaceae, intestinal Toll-like receptor-4 (TLR4) expression, circulating LPS, LPS-binding protein (LBP) and inflammatory cytokines, and a lower level of fecal butyrate, severer intestine destruction and cognitive impairment than mice that received microbiota from nPSCI patients (nPSCI mice). In addition, we observed exacerbations in blood-brain barrier (BBB) integrity, microglial activation, neuronal apoptosis in the CA1 region of the hippocampus, and Aß deposition in the thalamus of PSCI mice in comparison with nPSCI mice. Intraperitoneal injection of LPS after stroke caused similar pathology to those seen in PSCI mice. Supplementation with sodium butyrate (NaB) via drinking water rescued these detrimental changes in PSCI mice. CONCLUSIONS: Our data indicate a cause-effect relationship between gut microbiota and PSCI for the first time, which is likely mediated by inflammation-regulating metabolites including LPS and butyrate.

Congenitally underdeveloped intestine drives autism-related gut microbiota and behavior.

Autism spectrum disorder (ASD) is a neurological and developmental disorder accompanied by gut dysbiosis and gastrointestinal symptoms in most cases. However, the development of the autism-related gut microbiota and its relationship with intestinal dysfunction in ASD remain unclear. Using a valproic acid (VPA)-induced ASD mouse model, we showed a congenitally immature intestine of VPA-exposed mice accompanied by prominent oxidative stress and inflammation. Of note, the gut microbiota composition of VPA-exposed mice resembled that of control mice within 24 h after birth; however, their gut microbiota compositions differed on postnatal days 7 and 21. Oral administration of superoxide dismutase (SOD) to attenuate intestinal oxidative stress either before weaning or during juvenile restored the autism-associated gut microbiota, leading to the amelioration of autism-related behaviors. These findings collectively suggest the congenitally underdeveloped intestine as an early driving force shaping the autism-associated gut microbiota and host neurodevelopment through enhancing oxidative stress.

Rapid gut dysbiosis induced by stroke exacerbates brain infarction in turn.

OBJECTIVE: Stroke is a leading cause of death and disability worldwide. Neuroprotective approaches have failed in clinical trials, thus warranting therapeutic innovations with alternative targets. The gut microbiota is an important contributor to many risk factors for stroke. However, the bidirectional interactions between stroke and gut microbiota remain largely unknown. DESIGN: We performed two clinical cohort studies to capture the gut dysbiosis dynamics after stroke and their relationship with stroke prognosis. Then, we used a middle cerebral artery occlusion model to explore gut dysbiosis post-stroke in mice and address the causative relationship between acute ischaemic stroke and gut dysbiosis. Finally, we tested whether aminoguanidine, superoxide dismutase and tungstate can alleviate post-stroke brain infarction by restoring gut dysbiosis. RESULTS: Brain ischaemia rapidly induced intestinal ischaemia and produced excessive nitrate through free radical reactions, resulting in gut dysbiosis with Enterobacteriaceae expansion. Enterobacteriaceae enrichment exacerbated brain infarction by enhancing systemic inflammation and is an independent risk factor for the primary poor outcome of patients with stroke. Administering aminoguanidine or superoxide dismutase to diminish nitrate generation or administering tungstate to inhibit nitrate respiration all resulted in suppressed Enterobacteriaceae overgrowth, reduced systemic inflammation and alleviated brain infarction. These effects were gut microbiome dependent and indicated the translational value of the brain-gut axis in stroke treatment. CONCLUSIONS: This study reveals a reciprocal relationship between stroke and gut dysbiosis. Ischaemic stroke rapidly triggers gut microbiome dysbiosis with Enterobacteriaceae overgrowth that in turn exacerbates brain infarction.

Dysbiosis of the intestinal microbiota in neurocritically ill patients and the risk for death.

BACKGROUND: Despite the essential functions of the intestinal microbiota in human physiology, little has been reported about the microbiome in neurocritically ill patients. This investigation aimed to evaluate the characteristics of the gut microbiome in neurocritically ill patients and its changes after admission. Furthermore, we investigated whether the characteristics of the gut microbiome at admission were a risk factor for death within 180 days. METHODS: This prospective observational cohort study included neurocritically ill patients admitted to the neurological intensive care unit of a large university-affiliated academic hospital in Guangzhou. Faecal samples were collected within 72 h after admission (before antibiotic treatment) and serially each week. Healthy volunteers were recruited from a community in Guangzhou. The gut microbiome was monitored via 16S rRNA gene sequence analysis, and the associations with the clinical outcome were evaluated by a Cox proportional hazards model. RESULTS: In total, 98 patients and 84 age- and sex-matched healthy subjects were included in the analysis. Compared with healthy subjects, the neurocritically ill patients exhibited significantly different compositions of intestinal microbiota. During hospitalization, the α-diversity and abundance of Ruminococcaceae and Lachnospiraceae decreased significantly over time in patients followed longitudinally. The abundance of Enterobacteriaceae was positively associated with the modified Rankin Scale at discharge. In the multivariate Cox regression analysis, Christensenellaceae and Erysipelotrichaceae were associated with an increased risk of death. The increases in intestinal Enterobacteriales and Enterobacteriaceae during the first week in the neurological intensive care unit were associated with increases of 92% in the risk of 180-day mortality after adjustments. CONCLUSIONS: This analysis of the gut microbiome in 98 neurocritically ill patients indicates that the gut microbiota composition in these patients differs significantly from that in a healthy population and that the magnitude of this dysbiosis increases during hospitalization in a neurological intensive care unit. The gut microbiota characteristics seem to have an impact on patients' 180-day mortality. Gut microbiota analysis could hopefully predict outcome in the future.

Characterization of changes in extracellular polymeric substances and heavy metal speciation of waste activated sludge during typical oxidation solubilization processes.

Biopolymer solubilization is considered to be the rate-limiting stage of anaerobic digestion of waste activated sludge (WAS). Oxidation processes have been proven to be effective in disrupting sludge flocs and causing solubilization of the solid biopolymers. In this study, WAS was treated by NaNO2 or H2O2 oxidation at pH of 2. The changes in extracellular polymeric substances properties and the speciation of heavy metals were investigated. The results revealed that both NaNO2 and H2O2 treatments were effective in solubilizing organics in WAS, while the conversion of biopolymers in the two treatment processes was different. Free nitrous acid destroyed the gel network structure of EPS, and organic materials were released from the solid phase to the supernatant. Indigenous peroxidase catalyzed H2O2 to produce hydroxyl radicals which caused significant solubilization of biopolymers, and the protein-like substances were further degraded into micro-molecule polypeptides or amino acids at high dosages of H2O2. During the oxidation processes, Zn, Cd and Cu, with excellent mobility, tended to migrate to the supernatant, and thus were easy to remove through the liquid-solid separation process. Ni and As showed moderate migration ability, of which the residual fraction tended to transform into reducible and soluble fractions. With poor mobility, Cr and Pb mainly existed in the forms of residual and oxidizable fractions, which were difficult to dissolve and remove from WAS. Both NaNO2 and H2O2 treatment resulted in the enhancement of sludge solubilization efficiency and heavy metal mobility in WAS, but different heavy metals showed distinct migration and transformation behaviors.

Cholestyramine resin administration alleviated cerebral ischemic injury in obese mice by improving gut dysbiosis and modulating the bile acid profile.

Obesity is a risk factor for cerebrovascular diseases. Accumulating evidence has revealed that gut dysbiosis plays an important role in the pathophysiology of cerebrovascular diseases. However, little is known about the role of gut dysbiosis in stroke in obesity. In this study, we established a rodent middle cerebral artery occlusion (MCAO) model to investigate whether obesity-induced gut dysbiosis exacerbates cerebral ischemic injury and the role of the bile salt sequestrant cholestyramine resin (CR) in gut microbiota and stroke outcome in obese mice. Long-term 45% high-fat diet (HFD) diet (8 weeks) induced an obesity phenotype and caused gut dysbiosis, resulting in a larger infarct volume and higher serum levels of inflammatory cytokines after stroke, compared to those in the lean counterparts. LC-MS/MS and GC analysis revealed that obese mice with stroke developed an obviously perturbed bile acid (BA) profile characterized by higher levels of deoxycholic acid and its conjugated forms, and lower levels of butyrate in the cecal content. CR administration improved the obesity-induced dysbiotic microbiome, attenuated ischemic brain injury and modulated the stroke-perturbed BA profile. Furthermore, fecal microbiota transplantation (FMT) experiments revealed that the impact of obesity on stroke and the neuroprotective effects of CR were mediated by gut microbiota. In conclusion, Obesity induces gut dysbiosis, worsens stroke outcomes, and perturbs the BA profile. The dysbiotic microbiome is an important linkage between obesity and stroke. CR confers metabolic benefits and neuroprotective effects in obesity, perhaps by modulating gut microbial composition and BA metabolism.

Scalable and Mechanically Durable Superhydrophobic Coating of SiO2/Polydimethylsiloxane/Epoxy Nanocomposite.

The mechanical durability of superhydrophobic surfaces is of significance for their practical applications. However, few reports about superhydrophobic coating on certain substrates took into consideration both the mechanical stability of the superhydrophobic coating and adhesion stability between the coating and the substrate. Herein, we put forward a facile and efficient strategy to construct robust superhydrophobic coatings by simply spray-coating a composite suspension of SiO2 nanoparticles, polydimethylsiloxane (PDMS), and epoxy resin (EP) on substrates pretreated with an EP base-coating. The as-obtained coating exhibited excellent superhydrophobicity with water contact angle of 163° and sliding angle of 3.5°, which could endure UV irradiation of 180 h, immersion in acidic or basic solutions for 168 h, and outdoor exposure for over 30 days. Notably, the coating surface retained superhydrophobicity after being successively impacted with faucet water for 1 h, impinged with 360 g sand grains, and abraded with sandpaper of 120 grid under a load of 500 g for 5 m distance. The outstanding mechanical stability was mainly attributed to the cross-linking of EP and the elastic nature of PDMS which ensured strong cohesion inside the whole coating and to the substrate. Additionally, the coating showed self-healing capacity against O2 plasma etching. The method is simple with the materials commercially available and is expected to be widely applied in outdoor applications.

[Study on the pollen viability and stigma receptivity of Chrysanthemum morifolium 'Fubaiju'].

OBJECTIVE: To study the blooming habits, pollen viability and stigma receptivity of Chrysanthemum morifolium and provide theoretical basis for its breeding. METHODS: Explored the blooming habits by dynamic observation on the process of blossom, evaluated the pollen viability by germination in vitro culture method and estimated stigma receptivity by benzidine-hydrogen peroxide method. RESULTS: About the pollen viability, there were no significant differences between the flowers which in the same round of the capitulum; Tubular flowers in the center of a capitulum were significantly higher than that on the edge; In the morning pollen vitality gradually raised, during 11: 00 - 14: 00 maintained the highest, and then gradually decreased; Tubular flower began to loose powder on the third day, during 4th - 6th day the pollen viability was highest, respectively was 35.12%, 39.89%, 38.12%, then gradually decreased, on the 15th day was only 7.41%, finally turned into wither. Regard to the stigma receptivity, the center of a capitulum were significantly higher than that on the edge, outer edge ligulate flower had no receptivity; Revealed the strongest during 13: 00 - 14:00 in one day; During the 5th - 7th day was the strongest after flowering. The regulation of the stigma secreted mucus existed great consistency with the stigma receptivity, namely the stigma receptivity usually was strong when it secreted large number mucus. CONCLUSION: Understand the blossom habits of Chrysanthemun morifolium, as well as the dynamic changes regulation of pollen viability and stigma receptivity during its blossom, which could be used to select the flowers in a capitulum which are on the more suitable period and position for artificial pollination and hybridization breeding research.

The Spouses of Stroke Patients Have a Similar Oral Microbiome to Their Partners with an Elevated Risk of Stroke.

Spousal members who share no genetic relatedness show similar oral microbiomes. Whether a shared microbiome increases the risk of cerebrovascular disease is challenging to investigate. The aim of this study was to compare the oral microbiota composition of poststroke patients, their partners, and controls and to compare the risk of stroke between partners of poststroke patients and controls. Forty-seven pairs of spouses and 34 control subjects were recruited for the study. Alcohol use, smoking, metabolic disease history, clinical test results, and oral health were documented. Oral microbiome samples were measured by 16S rRNA gene sequencing. The risk of stroke was measured by risk factor assessment (RFA) and the Framingham Stroke Profile (FSP). Poststroke patients and their partners exhibited higher alpha diversity than controls. Principal-coordinate analysis (PCoA) showed that poststroke patients share a more similar microbiota composition with their partners than controls. The differentially abundant microbial taxa among the 3 groups were identified by linear discriminant analysis effect size (LEfSe) analysis. The risk factor assessment indicated that partners of poststroke patients had a higher risk of stroke than controls. Spearman correlation analysis showed that Prevotellaceae was negatively associated with RFA. Lactobacillales was negatively associated with FSP, while Campilobacterota and [Eubacterium]_nodatum_group were positively associated with FSP. These results suggest that stroke risk may be transmissible between spouses through the oral microbiome, in which several bacteria might be involved in the pathogenesis of stroke.

A Superhydrophobic Dual-Mode Film for Energy-Free Radiative Cooling and Solar Heating.

Traditional electric cooling in summer and coal heating in winter consume a huge amount of energy and lead to a greenhouse effect. Herein, we developed an energy-free dual-mode superhydrophobic film, which consists of a white side with porous coating of styrene-ethylene-butylene-styrene/SiO2 for radiative cooling and a black side with nanocomposite coating of carbon nanotubes/polydimethylsiloxane for solar heating. In the cooling mode with the white side, the film achieved a high sunlight reflection of 94% and a strong long-wave infrared emission of 92% in the range of 8-13 µm to contribute to a temperature drop of ∼11 °C. In the heating mode with the black side, the film achieved a high solar absorption of 98% to induce heating to raise the air temperature beneath by ΔT of ∼35.6 °C. Importantly, both sides of the film are superhydrophobic with a contact angle over 165° and a sliding angle near 0°, showing typical self-cleaning effects, which defend the surfaces from outdoor contamination, thus conducive to long-term cooling and heating. This dual-mode film shows great potential in outdoor applications as coverings for both cooling in hot summer and heating in winter without an energy input.

Effect of enteral nutrition on the intestinal microbiome and risk of death in ischemic stroke patients.

BACKGROUND: Studies have shown that the intestinal microbiome of stroke patients is significantly altered and that the degree of microbiota disturbance correlates with prognosis. Enteral nutrition (EN) can reshape the intestinal microbiome and is important for stroke patients with dysphagia. We aimed to describe the intestinal microbiome in patients with ischemic cerebral infarction receiving standard EN. METHODS: First, 17 healthy controls (HCs), 54 stroke patients with oral feeding (ON), and 50 stroke patients with EN were matched to investigate the changes in the intestinal microbiota with EN in the first week after admission and dynamic changes in the EN group in the second week. Second, we investigated the relationship between the intestinal microbiome and clinical characteristics in a larger sample of participants receiving EN (n = 147). Survival analysis was performed using Cox proportional hazards regression. The composition and structure of the intestinal microbiota were analyzed by 16S rRNA sequencing. RESULTS: Compared with the HC and ON groups, patients with EN exhibited significantly different compositions of the intestinal microbiota in the first week, including enrichment of the opportunistic pathogen Enterococcus and depletion of bacteria such as Lachnospiraceae, and Ruminococcus, which were further depleted in the second week. An increase in Parvimonas and Comamonas abundances was associated with an increased risk of 180-day mortality. CONCLUSIONS: The intestinal microbiota in ischemic stroke patients receiving EN is significantly altered, and specific strains of bacteria may be associated with prognosis and clinical indicators.

Superhydrophobic Porous Coating of Polymer Composite for Scalable and Durable Daytime Radiative Cooling.

Passive daytime radiative cooling (PDRC) technology provides an eco-friendly cooling strategy by reflecting sunlight reaching the surface and radiating heat underneath to the outer space through the atmospheric transparency window. However, PDRC materials face challenges in cooling performance degradation caused by outdoor contamination and requirements of easy fabrication approaches for scale-up and high cooling efficiency. Herein, a polymer composite coating of polystyrene, polydimethylsiloxane and poly(ethyl cyanoacrylate) (PS/PDMS/PECA) with superhydrophobicity and radiative cooling performance was fabricated and demonstrated to have sustained radiative cooling capability, utilizing the superhydrophobic self-cleaning property to maintain the optical properties of the coating surface. The prepared coating is hierarchically porous which exhibits an average solar reflectance of 96% with an average emissivity of 95% and superhydrophobicity with a contact angle of 160°. The coating realized a subambient radiative cooling of 12.9 °C in sealed air and 7.5 °C in open air. The self-cleaning property of the PS/PDMS/PECA coating helped sustain the cooling capacity for long-term outdoor applications. Moreover, the coating exhibited chemical resistance, UV resistance, and mechanical durability, which has promising applications in wider fields.

Epigenetic repression of THBD transcription by BRG1 contributes to deep vein thrombosis.

BACKGROUND: Deep vein thrombosis (DVT) with its major complication, pulmonary embolism, is a global health problem. Endothelial dysfunction is involved in the pathogenesis of DVT. We have previously demonstrated that endothelial specific deletion of Brahma-related gene 1 (BRG1) ameliorates atherosclerosis and aneurysm in animal models. Whether endothelial BRG1 contributes to DVT development remains undetermined. METHODS: DVT was induced in mice by ligation of inferior vena cava. Deletion of BRG1 in endothelial cells was achieved by crossing the Cdh5-ERT-Cre mice with the Brg1loxp/loxp mice. RESULTS: Here we report that compared to the wild type mice, BRG1 conditional knockout (CKO) mice displayed substantially decreased DVT susceptibility characterized by decreased weight and size of thrombus and reduced immune infiltration. In endothelial cells, thrombomodulin (THBD) expression was significantly decreased by TNF-α stimulation, while BRG1 knockdown or inhibition recovered THBD expression. Further analysis revealed that BRG1 deficiency decreased the CpG methylation levels of the THBD promoter induced by TNF-α. Mechanistically, BRG1 directly upregulated DNMT1 expression after TNF-α treatment in endothelial cells. More importantly, administration of a small-molecule BRG1 inhibitor PFI-3 displayed potent preventive and therapeutic potentials in the DVT model. CONCLUSIONS: Our findings implicate BRG1 as an important regulator of DVT pathogenesis likely through epigenetic regulation of THBD expression in endothelial cells and provide translational proof-of-concept for targeting BRG1 in DVT intervention.

Obesity, metabolic syndrome, adipocytes and vascular function: A holistic viewpoint.

1. Obesity is a metabolic disease of pandemic proportions largely arising from positive energy balance, a consequence of sedentary lifestyle, conditioned by environmental and genetic factors. Several central and peripheral neurohumoral factors (the major ones being the anorectic adipokines leptin and adiponecin and the orexigenic gut hormone ghrelin) acting on the anorectic (pro-opiomelanocortin and cocaine- and amphetamine-regulated transcript) and orexigenic (neuropeptide Y and agouti gene-related protein) neurons regulate energy balance. These neurons, mainly in the arcuate nucleus of the hypothalamus, project to parts of the brain modulating functions such as wakefulness, autonomic function and learning. A tilt in the anorectic-orexigenic balance, perhaps determined genetically, leads to obesity. 2. Excess fat deposition requires space, created by adipocyte (hypertrophy and hyperplasia) and extracellular matrix (ECM) remodelling. This process is regulated by several factors, including several adipocyte-derived Matrix metalloproteinases and the adipokine cathepsin, which degrades fibronectin, a key ECM protein. Excess fat, also deposited in visceral organs, generates chronic low-grade inflammation that eventually triggers insulin resistance and the associated comorbidities of metabolic syndrome (hypertension, atherosclerosis, dyslipidaemia and diabetes mellitus). 3. The perivascular adipose tissue (PVAT) has conventionally been considered non-physiological structural tissue, but has recently been shown to serve a paracrine function, including the release of adipose-derived relaxant and contractile factors, akin to the role of the vascular endothelium. Thus, PVAT regulates vascular function in vivo and in vitro, contributing to the cardiovascular pathophysiology of the metabolic syndrome. Defining the mechanism of PVAT regulation of vascular reactivity requires more and better controlled investigations than currently seen in the literature.

A GSK3-SRF Axis Mediates Angiotensin II Induced Endothelin Transcription in Vascular Endothelial Cells.

Endothelin, encoded by ET1, is a vasoactive substance primarily synthesized in vascular endothelial cells (VECs). Elevation of endothelin levels, due to transcriptional hyperactivation, has been observed in a host of cardiovascular diseases. We have previously shown that serum response factor (SRF) is a regulator of ET1 transcription in VECs. Here we report that angiotensin II (Ang II) induced ET1 transcription paralleled activation of glycogen synthase kinase 3 (GSK3) in cultured VECs. GSK3 knockdown or pharmaceutical inhibition attenuated Ang II induced endothelin expression. Of interest, the effect of GSK3 on endothelin transcription relied on the conserved SRF motif within the ET1 promoter. Further analysis revealed that GSK3 interacted with and phosphorylated SRF at serine 224. Phosphorylation of SRF by GSK3 did not influence its recruitment to the ET1 promoter. Instead, GSK3-mediated SRF phosphorylation potentiated its interaction with MRTF-A, a key co-factor for SRF, which helped recruit the chromatin remodeling protein BRG1 to the ET1 promoter resulting in augmented histone H3 acetylation/H3K4 trimethylation. Consistently, over-expression of a constitutively active GSK enhanced Ang II-induced ET1 transcription and knockdown of either MRTF-A or BRG1 abrogated the enhancement of ET1 transcription. In conclusion, our data highlight a previously unrecognized mechanism that contributes to the transcriptional regulation of endothelin. Targeting this GSK3-SRF axis may yield novel approaches in the intervention of cardiovascular diseases.