Epicardial Adipose Tissue in Patients with Chronic Obstructive Pulmonary Disease

Rationale

Epicardial Adipose Tissue (EAT) volume as determined by chest computed tomography (CT) is an independent marker of cardiovascular events in the general population. COPD patients have an increased risk of cardiovascular disease, however nothing is known about the EAT volume in this population.

Objectives

To assess EAT volume in COPD and explore its association with clinical and physiological variables of disease severity.

Methods

We measured EAT using low-dose CT in 171 stable COPD patients and 70 controls matched by age, smoking history and BMI. We determined blood pressure, cholesterol, glucose and HbA1c levels, microalbuminuria, lung function, BODE index, co-morbidity index and coronary artery calcium score (CAC). EAT volume were compared between groups. Uni and multivariate analyses explored the relationship between EAT volume and the COPD related variables.

Results

COPD patients had a higher EAT volume [143.7 (P_25–75, 108.3–196.6) vs 129.1 (P_25–75, 91.3–170.8) cm³, p = 0.02)] and the EAT volume was significantly associated with CAC (r = 0.38, p<0.001) and CRP (r = 0.32, p<0.001) but not with microalbuminuria (r = 0.12, p = 0.13). In COPD patients, EAT volume was associated with: age, pack-years, BMI, gender, FEV₁%, 6 MWD, MMRC and HTN. Multivariate analysis showed that only pack-years (B = 0.6, 95% CI: 0.5–1.3), BMI (B = 7.8, 95% CI: 5.7–9.9) and 6 MWD (B = −0.2, 95% CI: −0.3–−0.1), predicted EAT volume.

Conclusions

EAT volume is increased in COPD patients and is independently associated with smoking history, BMI and exercise capacity, all modifiable risk factors of future cardiovascular events. EAT volume could be a non-invasive marker of COPD patients at high risk for future cardiovascular events.     

Unraveling the Binding Mechanism of Trivalent Tumor Necrosis Factor Ligands and Their Receptors

Characterization of the binding of a tumor necrosis factor (TNF) ligand to its receptor(s) is pivotal to understand how these proteins initiate signal transduction pathways. Unfortunately, kinetic elucidation of these interactions is strongly hampered by the multivalent nature of the binding partners. The interaction between TNF-related apoptosis-inducing ligand and its death receptors was analyzed using in-depth applications of surface plasmon resonance technology. Variations in receptor density and sensor chip type allowed us to manipulate the stoichiometry of the formed complex, and the rate constants describing the binding of trimeric TNF-related apoptosis-inducing ligand to only one receptor molecule were determined. Remarkably, the affinity of this trimer-monomer complex is in the picomolar range, and its dissociation very slow. Further analysis showed that the second and third receptor molecules bind with lower affinity to the preformed trimer-monomer complex. This together with results obtained with receptor activator of NF-κB ligand and B cell-activating factor strongly suggests that the binding of TNF family ligands to their receptors is initiated via the formation of a trimer-monomer complex that is sufficiently stable to allow binding of two additional receptor molecules. These results suggest that avidity does not play a significant role and thus provide new insight in how TNF ligands form the biologically important complexes with their receptors.Cytokines are signaling molecules involved in a range of biological processes and diseases. Cytokines and receptors belonging to the TNF superfamily have been a subject of interest for developing novel therapies for numerous diseases (1). These cytokines e.g. TNFα, TRAIL,1 RANKL, and BAFF are type II transmembrane proteins, and the extracellular C-terminal moiety can be released by specific proteases to form a soluble and active protein consisting of three subunits of each ∼20 kDa (2). As one of the most promising anticancer therapeutic candidates, recombinant human TRAIL (rhTRAIL; comprising amino acids 114–281) is able to kill a variety of cancer cells but not healthy cells. Currently, rhTRAIL is being tested in clinical phase II studies as an anticancer biopharmaceutical (3).Despite good progress on structural insight, analysis of the interactions between TNF ligand family members and their receptors lacks unambiguous results. This seems mainly caused by the multivalent character of these molecules, i.e. trimeric cytokines but also often dimeric receptor-Fc fusions, which lead to complex kinetic behavior. In a series of experiments, we obtained several indications that surface plasmon resonance (SPR) assays with rhTRAIL WT and receptor-specific variants (4–6) offer opportunities to establish a better characterization of their interactions with receptor molecules. For this, we meticulously applied SPR technology to elucidate the dynamics of complex formation of this important group of cytokines. We used rhTRAIL WT; a DR5-specific mutant, rhTRAIL^D269H/E195R; and death receptors DR4 and DR5 to develop the method, but we show with examples of other members of the TNF family that the method is generally applicable. Apart from presenting a method allowing unambiguous affinity determination, our results demonstrate that the binding mechanism of these cytokines is initiated via a high affinity interaction with the first receptor molecule, bringing the cytokine to the membrane.     

Eph Family Receptors and Their Ligands Distribute in Opposing Gradients in the Developing Mouse Retina

The Eph family of receptor tyrosine kinases and their ligands can be divided into two specificity subclasses: the Eck-related receptors and their GPI-anchored ligands, and the Elk-related receptors and their transmembrane ligands. Previous reports demonstrated that Eck- and Elk-related receptors in the retina distribute in high temporal–low nasal and high ventral–low dorsal gradients, respectively. While others have focused on complementary ligand gradients in the retinal axon target, the tectum, we report that ligands from each subclass also distribute in gradients opposing those of their corresponding receptors within the retina itself. Moreover, ligand gradients in the retina precede ganglion cell genesis. These results support an intraretinal role for Eph family members in addition to their previously proposed role in the development of retinotectal topography. The distinct distributions of Eph family members suggest that each subclass specifies positional information along independent retinal axes.     

Modulation of Wnt signaling by Axin and Axil

The Wnt signaling pathway is conserved in various species from worms to mammals, and plays important roles in development, cellular proliferation, and differentiation. The molecular mechanisms by which the Wnt signal regulates cellular functions are becoming increasingly well understood. Wnt stabilizes cytoplasmic β-catenin, which stimulates the expression of genes including c-myc, c-jun, fra-1, and cyclin D1. Axin and its homolog Axil, newly recognized as components of the Wnt signaling pathway, negatively regulate this pathway. Other components of the Wnt signaling pathway, including Dvl, glycogen synthase kinase-3β (GSK-3β), β-catenin, and adenomatous polyposis coli (APC), interact with Axin, and the phosphorylation and stability of β-catenin are regulated in the Axin complex. Axil has similar functions to Axin. Thus, Axin and Axil act as scaffold proteins in the Wnt signaling pathway, thereby modulating the Wnt-dependent cellular functions.     

自然杀伤细胞受体及其配体表达的转录和表观遗传调控

自然杀伤(natural killer cell,NK)细胞受体及其配体在NK细胞发挥抗病毒、抗肿瘤和免疫调节作用中起重要作用.NK细胞功能的发挥取决于NK细胞受体及其配体的表达水平和其所传递信号的综合.病毒、肿瘤和热休克等刺激可以通过激活相应的转录调节因子,提高启动子活性而上调NKG2家族受体及其配体的表达,而启动子区DNA的甲基化状态、组蛋白的乙酰化和甲基化等表观遗传调控,在NK细胞受体及其配体的表达方面亦起重要作用,并决定NK细胞受体的克隆性分布.深入探讨NK细胞受体及其配体的表达调控机制,将为提高NK.细胞抗肿瘤和抗感染疗效提供新的策略.     

免疫细胞在棕色脂肪产热及白色脂肪棕色化过程中的功能研究进展

肥胖已经成为威胁人类健康的全球性问题,棕色脂肪(Brown adipose tissue,BAT)及米色脂肪因其能够通过产热作用增加能量消耗这一特性,已成为一种备受关注的潜在肥胖治疗方法。近年来的研究发现M2型巨噬细胞(Alternatively activated macrophages,M2 type)能够促进BAT产热和白色脂肪(White adipose tissue,WAT)的棕色化(即米色脂肪的形成过程),但随后的一些研究却得到了相反的结论。到目前为止,M2型巨噬细胞是否参与促进WAT的棕色化过程仍是一个备受争议的话题。主要对M2型巨噬细胞、II型固有淋巴细胞(Type 2 Innate Lymphoid Cells,ILC2s)和嗜酸性粒细胞(Eosinophils)对BAT产热和WAT的棕色化的促进作用,以及M2型巨噬细胞不参与/抑制WAT棕色化这两个方面的研究状况做一综述。     

Microbiota Depletion Impairs Thermogenesis of Brown Adipose Tissue and Browning of White Adipose Tissue

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Calcium Domains around Single and Clustered IP3 Receptors and Their Modulation by Buffers

We study Ca²⁺ release through single and clustered IP₃ receptor channels on the ER membrane under presence of buffer proteins. Our computational scheme couples reaction-diffusion equations and a Markovian channel model and allows our investigating the effects of buffer proteins on local calcium concentrations and channel gating. We find transient and stationary elevations of calcium concentrations around active channels and show how they determine release amplitude. Transient calcium domains occur after closing of isolated channels and constitute an important part of the channel's feedback. They cause repeated openings (bursts) and mediate increased release due to Ca²⁺ buffering by immobile proteins. Stationary domains occur during prolonged activity of clustered channels, where the spatial proximity of IP₃Rs produces a distinct [Ca²⁺] scale (0.5-10 μM), which is smaller than channel pore concentrations (>100 μM) but larger than transient levels. While immobile buffer affects transient levels only, mobile buffers in general reduce both transient and stationary domains, giving rise to Ca²⁺ evacuation and biphasic modulation of release amplitude. Our findings explain recent experiments in oocytes and provide a general framework for the understanding of calcium signals.     

Exploring the Role of Killer Cell Immunoglobulin-Like Receptors and Their HLA Class I Ligands in Autoimmune Hepatitis

Background

Natural killer cells are involved in the complex mechanisms underlying autoimmune diseases but few studies have investigated their role in autoimmune hepatitis. Killer immunoglobulin-like receptors are key regulators of natural killer cell-mediated immune responses.

Methods and Findings

KIR gene frequencies, KIR haplotypes, KIR ligands and combinations of KIRs and their HLA Class I ligands were investigated in 114 patients diagnosed with type 1 autoimmune hepatitis and compared with a group of 221 healthy controls. HLA Class I and Class II antigen frequencies were compared to those of 551 healthy unrelated families representative of the Sardinian population. In our cohort, type 1 autoimmune hepatitis was strongly associated with the HLA-B18, Cw5, DR3 haplotype. The KIR2DS1 activating KIR gene and the high affinity HLA-C2 ligands were significantly higher in patients compared to controls. Patients also had a reduced frequency of HLA-Bw4 ligands for KIR3DL1 and HLA-C1 ligands for KIR2DL3. Age at onset was significantly associated with the KIR2DS1 activating gene but not with HLA-C1 or HLA-C2 ligand groups.

Conclusions

The activating KIR gene KIR2DS1 resulted to have an important predictive potential for early onset of type 1 autoimmune hepatitis. Additionally, the low frequency of the KIR-ligand combinations KIR3DL1/HLA-Bw4 and KIR2DL3/HLA-C1 coupled to the high frequency of the HLA-C2 high affinity ligands for KIR2DS1 could contribute to unwanted NK cell autoreactivity in AIH-1.     

Cytotoxic Effects of the Selective Ligands of Membrane Progesterone Receptors in Human Pancreatic Adenocarcinoma Cells BxPC3

Biochemistry (Moscow) - Progesterone and its synthetic analogues act on cells through different types of receptors, affecting proliferation and apoptosis. These compounds exert their effect through...     

NPY Neuron-Specific Y2 Receptors Regulate Adipose Tissue and Trabecular Bone but Not Cortical Bone Homeostasis in Mice

Background

Y2 receptor signalling is known to be important in neuropeptide Y (NPY)-mediated effects on energy homeostasis and bone physiology. Y2 receptors are located post-synaptically as well as acting as auto receptors on NPY-expressing neurons, and the different roles of these two populations of Y2 receptors in the regulation of energy homeostasis and body composition are unclear.

Methodology/Principal Findings

We thus generated two conditional knockout mouse models, Y2^lox/lox and NPYCre/+;Y2^lox/lox, in which Y2 receptors can be selectively ablated either in the hypothalamus or specifically in hypothalamic NPY-producing neurons of adult mice. Specific deletion of hypothalamic Y2 receptors increases food intake and body weight compared to controls. Importantly, specific ablation of hypothalamic Y2 receptors on NPY-containing neurons results in a significantly greater adiposity in female but not male mice, accompanied by increased hepatic triglyceride levels, decreased expression of liver cartinine palmitoyltransferase (CPT1) and increased expression of muscle phosphorylated acetyl-CoA carboxylase (ACC). While food intake, body weight, femur length, bone mineral content, density and cortical bone volume and thickness are not significantly altered, trabecular bone volume and number were significantly increased by hypothalamic Y2 deletion on NPY-expressing neurons. Interestingly, in situ hybridisation reveals increased NPY and decreased proopiomelanocortin (POMC) mRNA expression in the arcuate nucleus of mice with hypothalamus-specific deletion of Y2 receptors in NPY neurons, consistent with a negative feedback mechanism between NPY expression and Y2 receptors on NPY-ergic neurons.

Conclusions/Significance

Taken together these data demonstrate the anti-obesogenic role of Y2 receptors in the brain, notably on NPY-ergic neurons, possibly via inhibition of NPY neurons and concomitant stimulation of POMC-expressing neurons in the arcuate nucleus of the hypothalamus, reducing lipogenic pathways in liver and/or skeletal muscle in females. These data also reveal as an anti-osteogenic effect of Y2 receptors on hypothalamic NPY-expressing neurons on trabecular but not on cortical bone.     

Human Adipose Tissue Derived Mesenchymal Stem Cells Aggravate Chronic Cyclosporin Nephrotoxicity by the Induction of Oxidative Stress

The aim of this study was to investigate whether hATMSCs protect against cyclosporine (CsA)-induced renal injury. CsA (7.5 mg/kg) and hATMSCs (3×10⁶/5 mL) were administered alone and together to rats for 4 weeks. The effect of hATMSCs on CsA-induced renal injury was evaluated by assessing renal function, interstitial fibrosis, infiltration of inflammatory cells, and apoptotic cell death. Four weeks of CsA-treatment produced typical chronic CsA-nephropathy. Combined treatment with CsA and hATMSCs did not prevent these effects and showed a trend toward further renal deterioration. To evaluate why hATMSCs aggravated CsA-induced renal injury, we measured oxidative stress, a major mechanism of CsA-induced renal injury. Both urine and serum 8-hydroxydeoxyguanosine(8-OHdG) levels were higher in the CsA+hATMSCs group than in the CsA group (P<0.05). An in vitro study showed similar results. Although the rate of apoptosis did not differ significantly between HK-2 cells cultured in hATMSCs-conditioned medium and those cultured in DMEM, addition of CsA resulted in greater apoptosis in HK-2 cells cultured in hATMSCs-conditioned medium. Addition of CsA increased oxidative stress in the hATMSCs-conditioned medium. The results of our study suggest that treatment with hATMSCs may aggravate CsA-induced renal injury because hATMSCs cause oxidative stress in the presence of CsA.     

Killer Cell Immunoglobulin-like Receptors and Their HLA Ligands are Related with the Immunopathology of Chagas Disease

The aim of this study was to investigate the influence of killer cell immunoglobulin-like receptor (KIR) genes and their human leucocyte antigen (HLA) ligands in the susceptibility of chronic Chagas disease. This case-control study enrolled 131 serologically-diagnosed Chagas disease patients (59 men and 72 women, mean age of 60.4 ± 9.8 years) treated at the University Hospital of Londrina and the Chagas Disease Laboratory of the State University of Maringa. A control group was formed of 165 healthy individuals - spouses of patients or blood donors from the Regional Blood Bank in Maringa (84 men and 81 women, with a mean age of 59.0 ± 11.4 years). Genotyping of HLA and KIR was performed by PCR-SSOP. KIR2DS2-C1 in the absence of KIR2DL2 (KIR2DS2⁺/2DL2^-/C1⁺) was more frequent in Chagas patients (P = 0.020; Pc = 0.040; OR = 2.14) and, in particular, those who manifested chronic chagasic cardiopathy—CCC (P = 0.0002; Pc = 0.0004; OR = 6.64; 95% CI = 2.30–18.60) when compared to the control group, and when CCC group was compared to the patients without heart involvement (P = 0.010; Pc = 0.020; OR = 3.97). The combination pair KIR2DS2⁺/2DL2^-/KIR2DL3⁺/C1⁺ was also positively associated with chronic chagasic cardiopathy. KIR2DL2 and KIR2DS2 were related to immunopathogenesis in Chagas disease. The combination of KIR2DS2 activating receptor with C1 ligand, in the absence of KIR2DL2, may be related to a risk factor in the chronic Chagas disease and chronic chagasic cardiopathy.     

Release of Glutamate and Aspartate from CA1 Synaptosomes: Selective Modulation of Aspartate Release by Ionotropic Glutamate Receptor Ligands

Abstract: Synaptosomes prepared from area CA1 of the rat hippocampus were used to determine (a) whether Schaffer collateral-commissural-ipsilateral associational terminals release both aspartate and glutamate in a Ca²⁺-dependent manner when reuptake of released glutamate is minimal and (b) whether autoreceptor mechanisms described in CA1 or hippocampal slices could reflect direct actions of glutamate receptor ligands on the synaptic terminal. When challenged for 1 min with either 25 m M K⁺ or 300 µ M 4-aminopyridine, CA1 synaptosomes released both glutamate and aspartate in a Ca²⁺-dependent manner. The glutamate/aspartate ratio was ∼5:1 in each case. K⁺-evoked glutamate release was unaffected by ligands active at NMDA or ( RS )-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors. Unlike glutamate release, the release of aspartate was enhanced by NMDA, and this effect was blocked by d -2-amino-5-phosphonovalerate ( d -AP5). Kainate selectively depressed and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) selectively increased the K⁺-evoked release of aspartate. AMPA enhanced aspartate release, like the antagonist CNQX. When applied in the presence of diazoxide, which blocks the desensitization of AMPA receptors, AMPA and kainate both depressed aspartate release. These findings support the view that Schaffer collateral-commissural-ipsilateral associational terminals release aspartate as well as glutamate and that these two release processes are regulated by different autoreceptor mechanisms.     

Modulation of Thyroid Hormone Receptors by Non-Thyroidal Stimuli

Abstract

The ability of non-thyroidal stimuli to affect the binding affinity and capacity of solubilized nuclear receptors for thyroid hormones was studied in a normal homeostatic system (erythropoiesis) and a pathobiologic one (lung-ozone interaction). No significant effects on affinity were found, as Kd control values for receptors derived from rat bone marrow averaged 57 (±28) pM while experimental (hypoxic) values averaged 89 (±55) pM. Kd control values in rat lung were found to average 142 (±22) pM while average values derived from experimental protocols with ozone and methimazole were 267 (±44) pM and 161 (±35) pM respectively. Finally, Kd control values for receptors derived from cultured MEL cells averaged 19 (±2.6) pM while experimental values during exposure to DMSO or IGFl were 23 (±3.6) pM and 26 (±11) pM respectively. In contrast, binding capacity (expressed as fmoles of hormone bound per unit protein of solubilized receptor) was markedly perturbed in several tisses by various agents: ozone effects on lung were shown by an average control value of 3.3 (±0.4) as opposed to an experimental average of 28 (±1.9); and hypoxia effects on erythroid tissue were displayed by an     

Characteristic Expression of Extracellular Matrix in Subcutaneous Adipose Tissue Development and Adipogenesis; Comparison with Visceral Adipose Tissue

Adipose tissue is a connective tissue specified for energy metabolism and endocrines, but functional differences between subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) have not been fully elucidated. To reveal the physiological role of SAT, we characterized in vivo tissue development and in vitro adipocyte differentiation. In a DNA microarray analysis of SAT and VAT in Wistar rats, functional annotation clusters of extracellular matrix (ECM)-related genes were found in SAT, and major ECM molecules expressed in adipose tissues were profiled. In a histological analysis and quantitative expression analysis, ECM expression patterns could be classified into two types: (i) a histogenesis-correlated type such as type IV and XV collagen, and laminin subunits, (ii) a high-SAT expression type such as type I, III, and V collagen and minor characteristic collagens. Type (i) was related to basal membrane and up-regulated in differentiated 3T3-L1 cells and in histogenesis at depot-specific timings. In contrast, type (ii) was related to fibrous forming and highly expressed in 3T3-L1 preadipocytes. Exceptionally, fibronectin was abundant in developed adipose tissue, although it was highly expressed in 3T3-L1 preadipocytes. The present study showed that adipose tissues site-specifically regulate molecular type and timing of ECM expression, and suggests that these characteristic ECM molecules provide a critical microenvironment, which may affect bioactivity of adipocyte itself and interacts with other tissues. It must be important to consider the depot-specific property for the treatment of obesity-related disorders, dermal dysfunction and for the tissue regeneration.