Evidence for anti-inflammatory effects and modulation of neurotransmitter metabolism by Salvia officinalis L.

BACKGROUND: Cognitive health is of great interest to society, with neuroinflammation and systemic inflammation age-related risk factors that are linked to declines in cognitive performance. Several botanical ingredients have been suggested to have benefits in this area including Salvia officinalis (sage), which has shown anti-inflammatory effects and exhibited promising cognitive improvements in multiple human studies. The current study demonstrates anti-inflammatory effects for S. officinalis across a broad set of in vitro models in human cells, and adds further evidence to support modulation of acetylcholine and monoamine neurostransmitter levels as mechanisms that contribute towards the benefits of the herb on cognitive health. METHODS: The effect of S. officinalis extract on release of multiple cytokines and chemokines was measured in human primary intestinal epithelial cells treated with or without LPS stimulation, and Blood Brain Barrier (BBB) cells in presence or absence of recombinant IL-17A and/or Human IL-17RA/IL-17R Antibody. Antioxidant effects were also assessed in BBB cells incubated with the extract and H2O2. The anti-inflammatory effects of S. officinalis extract were further assessed based on clinically-relevant biomarker readouts across 12 human primary cell-based disease models of the BioMAP Diversity PLUS panel. RESULTS: S. officinalis showed significant attenuation of the release of most cytokines/chemokines into apical media in LPS-stimulated intestinal cells, but small increases in the release of markers including IL-6, IL-8 in basolateral media; where TNF-α was the only marker to be significantly reduced. S. officinalis attenuated the release of CRP and VCAM-1 from BBB cells under IL-17A induced conditions, and also decreased H2O2 induced ROS overproduction in these cells. Phenotypic profiling with the BioMAP Diversity PLUS Panel identified additional anti-inflammatory mediators, and based on a similarity search analysis suggested potential mechanistic similarity to caffeic acid and drugs known to inhibit COMT and MAO activity to modulate monoamine metabolism. Subsequent in vitro assessment showed that S. officinalis was able to inhibit the activity of these same enzymes. CONCLUSIONS: S. officinalis extract showed anti-inflammatory effects across multiple human cell lines, which could potentially reduce peripheral inflammation and support cognitive health. S. officinalis extract also showed the ability to inhibit enzymes related to the metabolism of monoamine neurotransmitters, suggesting possible dopaminergic and serotonergic effects acting alongside proposed cholinergic effects to mediate acute cognitive performance benefits previously demonstrated for the extract.

Effects of Salvia officinalis L. and Chamaemelum nobile (L.) extracts on inflammatory responses in two models of human cells: Primary subcutaneous adipocytes and neuroblastoma cell line (SK-N-SH).

ETHNOPHARMACOLOGICAL RELEVANCE: Salvia officinalis L. (sage), and Chamaemelum nobile (L.) (chamomile) have been used traditionally to treat various inflammatory conditions. AIMS: Our study aims to investigate the anti-inflammatory properties of both plant extracts in IL-1ß-stimulated neuroblastoma cells (SK-N-SH) and human subcutaneous mature adipocytes, as well as their potential protective effects against mature adipocytes conditioned media (ACM)-induced neuro-inflammation. MATERIALS AND METHODS: Human subcutaneous mature adipocytes and neuroblastoma cells were treated with 5 µg/ml (low dose: LD) and 50 µg/ml (high dose: HD) of each extract, with or without 0.5 ng/ml of human recombinant IL-1ß. To understand the cross talk between fat tissue and neuronal cells, SK-N-SH cell line was incubated with ACM 10%, in presence or absence of both extracts LD and HD. Following 4, and 24 h incubation, the released MCP-1, IL-6, IL-8, TNF-α, ICAM-1, VCAM-1 and SAA levels were measured using MSD Cytokines and Chemokines assay kits, and the cells were used for gene expression. RNA was quantified using Qubit™ RNA HS Assay. RNA aliquots were shipped to Eurofins Genomics (Aarhus, Denmark) for expression analysis on the human Clariom™ GO Screen Assay (952,361; ThermoFisher). RESULTS: Chamomile showed stronger effects compared to sage in both cell lines, at 4 and 24 h. Adipocytes acute treatment with sage decreased MCP-1, IL-6, IL-8 (p < 0.001), and TNF-α (p < 0.05) basal levels. This was mirrored at MCP-1 transcriptional level. Chronic treatment with both extracts resulted in a significant reduction in ICAM-1, VCAM-1 and SAA (p < 0.001) levels, in IL-1ß-stimulated adipocytes. However, in SK-N-SH cells, sage increased the basal levels of many cytokines and chemokines on both protein and transcriptional levels. This was also observed in IL-1ß-stimulated cells. In chamomile treated SK-N-SH cells, acute and chronic treatments decreased MCP-1 (p < 0.001), IL-6 (p < 0.01), TNF-α (p < 0.01), and IL-8 (p < 0.001) basal levels. In IL1-ß-stimulated SK-N-SH cells, chamomile HD induced a significant reduction in TNF-α after both acute and chronic treatments respectively, by 52% and 81%. At transcriptional level, this effect was only reflected at 4 h. ICAM-1, VCAM-1 and SAA levels were reduced in most of the studied conditions. In IL-1ß treated adipocytes, chamomile showed stronger reduction in MCP-1, ICAM-1 and VCAM-1 expression, however no significant reduction in TNF-α and IL-8 was observed, despite the decrease in basal levels. In SK-N-SH cells, ACM increased MCP-1, IL-6, IL-8, TNF-α, VCAM-1 and SAA levels. Sage HD acute treatment resulted in a reduction of ACM effect on IL-6, IL-8 and VCAM-1, with greater effect of chamomile on MCP-1 (p < 0.05); IL-6 (p < 0.001); TNF-α (p < 0.001); VCAM-1 (p < 0.001); and SAA (p < 0.001). This protective effect was also observed after chronic treatment. However, both extracts potentiated significantly the ACM-pro-inflammatory effect on IL-8 (p < 0.001). CONCLUSIONS: Sage decreased the pro-inflammatory markers mostly in human adipocytes, whereas chamomile showed a strong reduction in both cell populations. Both extracts reduced the ACM-induced inflammation effect and might be used as a preventive treatment for late-life cognitive impairment related to low-grade chronic inflammation associated with obesity. Further studies are needed to investigate their combination on other chronic inflammation-related diseases such as type 2 diabetes or rheumatoid arthritis.

Primary Adipocytes as a Model for Insulin Sensitivity.

Obesity and its comorbidity insulin resistance lead to the development of chronic metabolic diseases, such as impaired fasted blood glucose and type 2 diabetes. Adipose tissue plays an important role in whole-body glucose homeostasis, particularly in obese individuals; therefore, many in vivo models of type 2 diabetes are obese, such as Lepob/ob and Leprdb/db mice or ZDF rats. Primary adipocytes therefore represent an attractive in vitro model to study insulin-mediated glucose uptake to investigate the mechanisms of insulin resistance and explore the potential insulin-sensitizing properties of new antidiabetic drugs.Primary adipocytes are isolated by collagenase digestion of adipose tissue, Glucose transport is evaluated by the measurement of intracellular uptake of a tracer (D-[U14C] glucose). The uptake of [U-14 C] glucose reflects directly glucose transport.In this chapter, we will describe the protocol for the isolation of primary rodent adipocytes and the measurement of basal and insulin-stimulated glucose uptake.

IL-33 stimulates expression of the GPR84 (EX33) fatty acid receptor gene and of cytokine and chemokine genes in human adipocytes.

Expression of GPCR fatty acid sensor/receptor genes in adipocytes is modulated by inflammatory mediators, particularly IL-1ß. In this study we examined whether the IL-1 gene superfamily member, IL-33, also regulates expression of the fatty acid receptor genes in adipocytes. Human fat cells, differentiated from preadipocytes, were incubated with IL-33 at three different dose levels for 3 or 24 h and mRNA measured by qPCR. Treatment with IL-33 induced a dose-dependent increase in GPR84 mRNA at 3 h, the level with the highest dose being 13.7-fold greater than in controls. Stimulation of GPR84 expression was transitory; the mRNA level was not elevated at 24 h. In contrast to GPR84, IL-33 had no effect on GPR120 expression. IL-33 markedly stimulated expression of the IL1B, CCL2, IL6, CXCL2 and CSF3 genes, but there was no effect on ADIPOQ expression. The largest effect was on CSF3, the mRNA level of which increased 183-fold over controls at 3 h with the highest dose of IL-33; there was a parallel increase in the secretion of G-CSF protein into the medium. It is concluded that in human adipocytes IL-33, which is synthesised in adipose tissue, has a strong stimulatory effect on the expression of cytokine and chemokine genes, particularly CSF3, and on the expression of GPR84, a pro-inflammatory fatty acid receptor.

Preventive effects of Salvia officinalis leaf extract on insulin resistance and inflammation in a model of high fat diet-induced obesity in mice that responds to rosiglitazone.

BACKGROUND: Salvia officinalis (sage) is a native plant to the Mediterranean region and has been used for a long time in traditional medicine for various diseases. We investigated possible anti-diabetic, anti-inflammatory and anti-obesity effects of sage methanol (MetOH) extract in a nutritional mouse model of obesity, inflammation and insulin resistance, as well as its effects on lipolysis and lipogenesis in 3T3-L1 cells. METHODS: Diet-induced obese (DIO) mice were treated for five weeks with sage methanol extract (100 and 400 mg kg-1/day bid), or rosiglitazone (3 mg kg-1/day bid), as a positive control. Energy expenditure, food intake, body weight, fat mass, liver glycogen and lipid content were evaluated. Blood glucose, and plasma levels of insulin, lipids leptin and pro- and anti-inflammatory cytokines were measured throughout the experiment. The effects of sage MetOH extract on lipolysis and lipogenesis were tested in vitro in 3T3-L1 cells. RESULTS: After two weeks of treatment, the lower dose of sage MetOH extract decreased blood glucose and plasma insulin levels during an oral glucose tolerance test (OGTT). An insulin tolerance test (ITT), performed at day 29 confirmed that sage improved insulin sensitivity. Groups treated with low dose sage and rosiglitazone showed very similar effects on OGTT and ITT. Sage also improved HOMA-IR, triglycerides and NEFA. Treatment with the low dose increased the plasma levels of the anti-inflammatory cytokines IL-2, IL-4 and IL-10 and reduced the plasma level of the pro-inflammatory cytokines IL-12, TNF-α, and KC/GRO. The GC analysis revealed the presence of two PPARs agonist in sage MetOH extract. In vitro, the extract reduced in a dose-related manner the accumulation of lipid droplets; however no effect on lipolysis was observed. CONCLUSIONS: Sage MetOH extract at low dose exhibits similar effects to rosiglitazone. It improves insulin sensitivity, inhibits lipogenesis in adipocytes and reduces inflammation as judged by plasma cytokines. Sage presents an alternative to pharmaceuticals for the treatment of diabetes and associated inflammation.

IL-1ß and TNFα inhibit GPR120 (FFAR4) and stimulate GPR84 (EX33) and GPR41 (FFAR3) fatty acid receptor expression in human adipocytes: implications for the anti-inflammatory action of n-3 fatty acids.

Regulation of the expression of GPCR fatty acid receptor genes has been examined in human adipocytes differentiated in culture. TNFα and IL-1ß induced a marked reduction in GPR120 expression, mRNA level falling 17-fold at 24 h in adipocytes incubated with TNFα. In contrast, GPR84 mRNA was dramatically increased by these cytokines (>500-fold for IL-1ß at 4 h); GPR41 expression was also stimulated. Rosiglitazone did not affect GPR84 expression, but GPR120 and GPR41 expression increased. Dexamethasone, insulin, linoleic and docosahexaenoic acids (DHA), and TUG891 (GPR120 agonist) had little effect on GPR120 and GPR84 expression. TUG891 did not attenuate the pro-inflammatory actions of TNFα and IL-1ß. DHA slightly countered the actions of IL-1ß on CCL2, IL6 and ADIPOQ expression, though not on secretion of these adipokines. GPR120 and GP84 gene expression in human adipocytes is highly sensitive to pro-inflammatory mediators; the inflammation-induced inhibition of GPR120 expression may compromise the anti-inflammatory action of GPR120 agonists.

PCR arrays indicate that the expression of extracellular matrix and cell adhesion genes in human adipocytes is regulated by IL-1ß (interleukin-1ß).

The role of IL-1ß in regulating the expression of extracellular matrix (ECM) and cell adhesion genes in human adipocytes has been examined. Adipocytes differentiated in culture were incubated with IL-1ß for 4 or 24 h and RNA probed with PCR arrays for 84 ECM and cell adhesion genes. Treatment with IL-1ß resulted in changes in the expression at one or both time points of ∼50% of the genes probed by the arrays, the majority being down-regulated. Genes whose expression was down-regulated by IL-1ß included those encoding several collagen chains and integrin subunits. In contrast, IL-1ß induced substantial increases (>10-fold) in the expression of ICAM1, VCAM1, MMP1 and MMP3; the secretion of the encoded proteins was also markedly stimulated. IL-1ß has a pervasive effect on the expression of ECM and cell adhesion genes in human adipocytes, consistent with the derangement of tissue structure during inflammation in white fat.

IL-1ß (interleukin-1ß) stimulates the production and release of multiple cytokines and chemokines by human preadipocytes.

The effect of IL-1ß on cytokine and chemokine production by human preadipocytes has been examined. Preadipocytes were incubated with IL-1ß, and cytokine and chemokine release was measured at 24 h by protein arrays, while the expression of cytokine/chemokine genes was assessed by qPCR at 4 and 24 h. IL-1ß stimulated the secretion of multiple cytokines/chemokines, including IL-6, IL-8, IL-10, IL-13, MCP-4, TNFα and IP-10. IL-10 was not released by un-stimulated preadipocytes, while IL-6 exhibited the greatest response to IL-1ß (453-fold increase). IL-16 and IL-12p40 did not respond to IL-1ß. qPCR demonstrated that IL-1ß markedly stimulated CCL3, CSF3 and CXCL10 expression at 4 h (>900-fold mRNA increase). A time-course indicated that while CCL13 (encoding MCP-4) exhibited minimal basal expression in preadipocytes, expression increased progressively following differentiation. Human preadipocytes are highly sensitive to IL-1ß, the cytokine stimulating a major inflammatory response in these cells similar to that in mature adipocytes.

Comparison of potential preventive effects of pomegranate flower, peel and seed oil on insulin resistance and inflammation in high-fat and high-sucrose diet-induced obesity mice model.

OBJECTIVE: The potentially beneficial effects of pomegranate peel (PPE), flower (PFE) and seed oil (PSO) extracts, in comparison with rosiglitazone, on adiposity, lipid profile, glucose homoeostasis, as well as on the underlying inflammatory mechanisms, were examined in high-fat and high-sucrose (HF/HS) diet-induced obese (DIO) mice. MEASUREMENTS: Body weight, body fat, energy expenditure, food and liquid intake, blood glucose, and plasma levels of insulin, lipids and cytokines were measured. RESULTS: After two weeks, PSO (2 ml/kg/day) and rosiglitazone (3 mg/kg/day) had not improved glucose intolerance. After 4 weeks, both treatments significantly reduced fasting blood glucose and an insulin tolerance test showed that they also improved insulin sensitivity. Treatment with PPE, PFE and PSO, reduced the plasma levels of the pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α), and PFE increased the level of the anti-inflammatory cytokine interleukin-10 (IL-10). CONCLUSION: PPE, PFE and PSO have anti-inflammatory properties. PSO also improved insulin sensitivity.

PCR array and protein array studies demonstrate that IL-1ß (interleukin-1ß) stimulates the expression and secretion of multiple cytokines and chemokines in human adipocytes.

The role of IL-1ß in regulating the expression and secretion of cytokines and chemokines by human adipocytes was examined. Adipocytes were incubated with human IL-1ß for 4 or 24 h. The expression of a panel of 84 cytokine/chemokine genes was probed using PCR arrays. IL-1ß stimulated the expression of >30 cytokine/chemokine genes on the arrays; 15 showed >100-fold increases in mRNA at 4 or 24 h including CSF3, CXCL1, CXCL2, CXCL12 and IL8. CSF3 exhibited a 10,000-fold increase in mRNA at 4 h. ADIPOQ was among the genes whose expression was inhibited. Protein arrays were used to examine the secretion of cytokines/chemokines from adipocytes. IL-1ß stimulated the secretion of multiple cytokines/chemokines including MCP-1, IL-8, IP-10, MIP-1α and MCP-4. The most responsive was IP-10, which exhibited a 5000-fold increase in secretion with IL-1ß. IL-1ß is likely to play a substantial role in stimulating the inflammatory response in human adipocytes in obesity.

Evidence from studies in rodents and in isolated adipocytes that agonists of the chemerin receptor CMKLR1 may be beneficial in the treatment of type 2 diabetes.

The literature is unclear on whether the adipokine chemerin has pro- or anti-inflammatory properties or plays any role in the aetiology of type 2 diabetes or obesity. To address these questions, and in particular the potential of agonists or antagonists of the chemerin receptor CMKLR1 in the treatment of type 2 diabetes and obesity, we studied the metabolic phenotypes of both male and female, CMKLR1 knockout and heterozygote mice. We also investigated changes in plasma chemerin levels and chemerin gene mRNA content in adipose tissue in models of obesity and diabetes, and in response to fasting or administration of the insulin sensitizing drug rosiglitazone, which also has anti-inflammatory properties. The effects of murine chemerin and specific C-terminal peptides on glucose uptake in wild-type and CMKLR1 knockout adipocytes were investigated as a possible mechanism by which chemerin affects the blood glucose concentration. Both male and female CMKLR1 knockout and heterozygote mice displayed a mild tendency to obesity and impaired glucose homeostasis, but only when they were fed on a high-fat died, rather than a standard low-fat diet. Obesity and impaired glucose homeostasis did not occur concurrently, suggesting that obesity was not the sole cause of impaired glucose homeostasis. Picomolar concentrations of chemerin and its C15- and C19-terminal peptides stimulated glucose uptake in the presence of insulin by rat and mouse wild-type epididymal adipocytes, but not by murine CMKLR1 knockout adipocytes. The insulin concentration-response curve was shifted to the left in the presence of 40 pM chemerin or its C-15 terminal peptide. The plasma chemerin level was raised in diet-induced obesity and ob/ob but not db/db mice, and was reduced by fasting and, in ob/ob mice, by treatment with rosiglitazone. These findings suggest that an agonist of CMKLR1 is more likely than an antagonist to be of value in the treatment of type 2 diabetes and to have associated anti-obesity and anti-inflammatory activities. One mechanism by which an agonist of CMKLR1 might improve glucose homeostasis is by increasing insulin-stimulated glucose uptake by adipocytes.

Stimulation of glucose uptake in murine soleus muscle and adipocytes by 5-(4-phenoxybutoxy)psoralen (PAP-1) may be mediated by Kv1.5 rather than Kv1.3.

Kv1 channels are shaker-related potassium channels that influence insulin sensitivity. Kv1.3(-/-) mice are protected from diet-induced insulin resistance and some studies suggest that Kv1.3 inhibitors provide similar protection. However, it is unclear whether blockade of Kv1.3 in adipocytes or skeletal muscle increases glucose uptake. There is no evidence that the related channel Kv1.5 has any influence on insulin sensitivity and its expression in adipose tissue has not been reported. PAP-1 is a selective inhibitor of Kv1.3, with 23-fold, 32-fold and 125-fold lower potencies as an inhibitor of Kv1.5, Kv1.1 and Kv1.2 respectively. Soleus muscles from wild-type and genetically obese ob/ob mice were incubated with 2-deoxy[1-(14)C]-glucose for 45 min and formation of 2-deoxy[1-(14)C]-glucose-6-phosphate was measured. White adipocytes were incubated with D-[U-(14)C]-glucose for 1 h. TNFα and Il-6 secretion from white adipose tissue pieces were measured by enzyme-linked-immunoassay. In the absence of insulin, a high concentration (3 µM) of PAP-1 stimulated 2-deoxy[1-14C]-glucose uptake in soleus muscle of wild-type and obese mice by 30% and 40% respectively, and in adipocytes by 20% and 50% respectively. PAP-1 also stimulated glucose uptake by adipocytes at the lower concentration of 1 µM, but at 300 nM, which is still 150-fold higher than its EC50 value for inhibition of the Kv1.3 channel, it had no effect. In the presence of insulin, PAP-1 (3 µM) had a significant effect only in adipocytes from obese mice. PAP-1 (3 µM) reduced the secretion of TNFα by adipose tissue but had no effect on the secretion of IL-6. Expression of Kv1.1, Kv1.2, Kv1.3 and Kv1.5 was determined by RT-PCR. Kv1.3 and Kv1.5 mRNA were detected in liver, gastrocnemius muscle, soleus muscle and white adipose tissue from wild-type and ob/ob mice, except that Kv1.3 could not be detected in gastrocnemius muscle, nor Kv1.5 in liver, of wild-type mice. Expression of both genes was generally higher in liver and muscle of ob/ob mice compared to wild-type mice. Kv1.5 appeared to be expressed more highly than Kv1.3 in soleus muscle, adipose tissue and adipocytes of wild-type mice. Expression of Kv1.2 appeared to be similar to that of Kv1.3 in soleus muscle and adipose tissue, but Kv1.2 was undetectable in adipocytes. Kv1.1 could not be detected in soleus muscle, adipose tissue or adipocytes. We conclude that inhibition of Kv1 channels by PAP-1 stimulates glucose uptake by adipocytes and soleus muscle of wild-type and ob/ob mice, and reduces the secretion of TNFα by adipose tissue. However, these effects are more likely due to inhibition of Kv1.5 than to inhibition of Kv1.3 channels.

Male mice that lack the G-protein-coupled receptor GPR41 have low energy expenditure and increased body fat content.

SCFA are produced in the gut by bacterial fermentation of undigested carbohydrates. Activation of the Gαi-protein-coupled receptor GPR41 by SCFA in ß-cells and sympathetic ganglia inhibits insulin secretion and increases sympathetic outflow, respectively. A possible role in stimulating leptin secretion by adipocytes is disputed. In the present study, we investigated energy balance and glucose homoeostasis in GPR41 knockout mice fed on a standard low-fat or a high-fat diet. When fed on the low-fat diet, body fat mass was raised and glucose tolerance was impaired in male but not female knockout mice compared to wild-type mice. Soleus muscle and heart weights were reduced in the male mice, but total body lean mass was unchanged. When fed on the high-fat diet, body fat mass was raised in male but not female GPR41 knockout mice, but by no more in the males than when they were fed on the low-fat diet. Body lean mass and energy expenditure were reduced in male mice but not in female knockout mice. These results suggest that the absence of GPR41 increases body fat content in male mice. Gut-derived SCFA may raise energy expenditure and help to protect against obesity by activating GPR41.

Contrasts between the effects of zinc-α2-glycoprotein, a putative ß3/2-adrenoceptor agonist and the ß3/2-adrenoceptor agonist BRL35135 in C57Bl/6 (ob/ob) mice.

Previous studies by Tisdale et al. have reported that zinc-α(2)-glycoprotein (ZAG (AZGP1)) reduces body fat content and improves glucose homeostasis and the plasma lipid profile in Aston (ob/ob) mice. It has been suggested that this might be mediated via agonism of ß(3)- and possibly ß(2)-adrenoceptors. We compared the effects of dosing recombinant human ZAG (100 µg, i.v.) and BRL35135 (0.5 mg/kg, i.p.), which is in rodents a 20-fold selective ß(3)- relative to ß(2)-adrenoceptor agonist, given once daily for 10 days to male C57Bl/6 Lep(ob)/Lep(ob) mice. ZAG, but not BRL35135, reduced food intake. BRL35135, but not ZAG, increased energy expenditure acutely and after sub-chronic administration. Only BRL35135 increased plasma concentrations of glycerol and non-esterified fatty acid. Sub-chronic treatment with both ZAG and BRL35135 reduced fasting blood glucose and improved glucose tolerance, but the plasma insulin concentration 30 min after administration of glucose was lowered only by BRL35135. Both ZAG and BRL35135 reduced ß(1)-adrenoceptor mRNA levels in white adipose tissue, but only BRL35135 reduced ß(2)-adrenoceptor mRNA. Both ZAG and BRL35135 reduced ß(1)-adrenoceptor mRNA levels in brown adipose tissue, but neither influenced ß(2)-adrenoceptor mRNA, and only BRL35135 increased ß(3)-adrenoceptor and uncoupling protein-1 (UCP1) mRNA levels in brown adipose tissue. Thus, ZAG and BRL35135 had similar effects on glycaemic control and shared some effects on ß-adrenoceptor gene expression in adipose tissue, but ZAG did not display the thermogenic effects of the ß-adrenoceptor agonist, nor did it increase ß(3)-adrenoceptor or UCP1 gene expression in brown adipose tissue. ZAG does not behave as a typical ß(3/2)-adrenoceptor agonist.

Roles of GPR41 and GPR43 in leptin secretory responses of murine adipocytes to short chain fatty acids.

GPR41 is reportedly expressed in murine adipose tissue and mediates short chain fatty acid (SCFA)-stimulated leptin secretion by activating Galpha(i). Here, we agree with a contradictory report in finding no expression of GPR41 in murine adipose tissue. Nevertheless, in the presence of adenosine deaminase to minimise Galpha(i) signalling via the adenosine A1 receptor, SCFA stimulated leptin secretion by adipocytes from wild-type but not GPR41 knockout mice. Expression of GPR43 was reduced in GPR41 knockout mice. Acetate but not butyrate stimulated leptin secretion in wild-type mesenteric adipocytes, consistent with mediation of the response by GPR43 rather than GPR41. Pertussis toxin prevented stimulation of leptin secretion by propionate in epididymal adipocytes, implicating Galpha(i) signalling mediated by GPR43 in SCFA-stimulated leptin secretion.

Chemerin, a novel adipokine in the regulation of angiogenesis.

CONTEXT: Chemerin is a new adipokine associated with obesity and the metabolic syndrome. Gene expression levels of chemerin were elevated in the adipose depots of obese compared with lean animals and was markedly elevated during differentiation of fibroblasts into mature adipocytes. OBJECTIVE: The objective of the study was to identify factors that affect the regulation and potential function of chemerin using a genetics approach. DESIGN, SETTING, PATIENTS, AND INTERVENTION: Plasma chemerin levels were measured in subjects from the San Antonio Family Heart Study, a large family-based genetic epidemiological study including 1354 Mexican-American individuals. Individuals were randomly sampled without regard to phenotype or disease status. MAIN OUTCOME MEASURES: A genome-wide association analysis using 542,944 single-nucleotide polymorphisms in a subset of 523 of the same subjects was undertaken. The effect of chemerin on angiogenesis was measured using human endothelial cells and interstitial cells in coculture in a specially formulated medium. RESULTS: Serum chemerin levels were found to be highly heritable (h(2) = 0.25; P = 1.4 x 10(-9)). The single-nucleotide polymorphism showing strongest evidence of association (rs347344; P = 1.4 x 10(-6)) was located within the gene encoding epithelial growth factor-like repeats and discoidin I-like domains 3, which has a known role in angiogenesis. Functional angiogenesis assays in human endothelial cells confirmed that chemerin significantly mediated the formation of blood vessels to a similar extent as vascular endothelial growth factor. CONCLUSION: Here we demonstrate for the first time that plasma chemerin levels are significantly heritable and identified a novel role for chemerin as a stimulator of angiogenesis.