Increased expression of the adipokine genes resistin and fasting-induced adipose factor in hypoxic/ischaemic mouse brain

Serum Angiopoietin-Like Protein 4 as a Biomarker for Acute Ischemic Stroke Severity and Dynamic Changes

BACKGROUND

Angiopoietin-like protein 4 (ANGPTL4) is critical for vascular integrity and reducing inflammation in ischemic and hypoxic brain injuries. However, limited studies have evaluated ANGPTL4's role in acute ischemic stroke (AIS) assessment, and its expression patterns across AIS phases remain unclear.

METHODS

The severity of AIS at admission was assessed using the National Institutes of Health Stroke Scale (NIHSS). The association between serum ANGPTL4 level and the occurrence of AIS was examined using logistic regression analysis. The diagnostic accuracy of serum ANGPTL4 level for AIS severity was assessed using receiver operating characteristic curves.

RESULTS

This study included 389 AIS patients and 133 healthy individuals. There was a notable increase in the occurrence of AIS associated with rising serum ANGPTL4 levels (odds ratio [OR] 1.03, 95% confidence interval [CI]: 1.02-1.06; p < 0.001). A higher serum level of ANGPTL4 was also found to be associated with severe AIS, as indicated by an AUC of 0.848. Additionally, we observed significant dynamic changes in ANGPTL4 levels, with a marked decrease at 1 week or 2 weeks after admission compared with the acute phase (the day after admission; both p < 0.001).

CONCLUSIONS

Our findings suggest a robust association between elevated serum ANGPTL4 levels and the presence and severity of AIS. Importantly, this study is distinguished by its novel focus on the temporal dynamics of ANGPTL4 levels, which underscores its potential as a biomarker for AIS monitoring and provides new insights into AIS pathophysiology.

Angiopoietin-like protein 4 and clinical outcomes in ischemic stroke patients

Aims

Angiopoietin‐like protein 4 (ANGPTL‐4) had been reported to be associated with the risk of ischemic stroke, but its prognostic value remained unclear. The aim of this study was to investigate the association between plasma ANGPTL‐4 concentrations and prognosis of ischemic stroke.

Methods

Baseline plasma ANGPTL‐4 concentrations were measured in 3379 acute ischemic stroke patients. The primary outcome was a combination of death or major disability (modified Rankin Scale score, ≥3) at 3 months after ischemic stroke.

Results

At 3 months after ischemic stroke, 850 (26.16%) participants experienced major disability or died (750 major disabilities and 100 deaths). After adjusting for important covariates, odds ratios for the highest tertile of plasma ANGPTL‐4 concentrations were 1.59 (1.22–2.06) for primary outcome, 1.53 (1.18–1.97) for major disability, and 2.03 (1.03–4.00) for death when compared with the lowest tertile of plasma ANGPTL‐4 concentrations. For 1‐SD increase in log‐ANGPTL‐4 concentrations (0.44 ng/mL), the adjusted odds ratios were 1.24 (1.11–1.38), 1.14 (1.03–1.27), and 1.72 (1.32–2.23), respectively. Adding ANGPTL‐4 to a model containing conventional risk factors improved risk prediction for composite outcome of death and major disability.

Conclusion

Higher plasma ANGPTL‐4 concentration was associated with poor prognosis in acute ischemic stroke patients, suggesting that ANGPTL‐4 might be a prognostic marker for ischemic stroke.

Cerebrovascular Disease: Consequences of Obesity-Induced Endothelial Dysfunction

Despite the well-known global impact of overweight and obesity in the incidence of cerebrovascular disease, many aspects of this association are still inconsistently defined. In this chapter we aim to present a critical review on the links between obesity and both ischemic and hemorrhagic stroke and discuss its influence on functional outcomes, survival, and current treatments to acute and chronic stroke. The role of cerebrovascular endothelial function and respective modulation is also described as well as its laboratory and clinical assessment. In this context, the major contributing mechanisms underlying obesity-induced cerebral endothelial function (adipokine secretion, insulin resistance, inflammation, and hypertension) are discussed. A special emphasis is given to the participation of adipokines in the pathophysiology of stroke, namely adiponectin, leptin, resistin, apelin, and visfatin.

Relevance Study on Cerebral Infarction and Resistin Gene Polymorphism in Chinese Han Population

Recent research on genome-wide associations has implicated that the serum resistin level and its gene polymorphism are associated with cerebral infarction (CI) morbidity and prognosis, and could thereby regulate CI. This study aimed to investigate the association between the resistin single nucleotide polymorphism (SNP) and the susceptibility to CI in the Chinese Han population. A total of 550 CI patients and 313 healthy controls were genotyped. Nine SNPs of the resistin gene previously shown were sequenced and assessed for an association with CI. The numbers of GG genotype carriers of rs3219175 and rs3486119 in the CI group were significantly higher than those in the control group among the middle-aged group (aged 45-65), at 76% vs 67.9% (P=0.025) and 75.5% vs 67.9% (P=0.031). rs3219175 and rs34861192 were associated with CI in the dominant and superdominant models according to the genetic model analysis (P<0.05). Meanwhile, there was strong linkage disequilibrium among the rs34124816, rs3219175, rs34861192, rs1862513, rs3745367, 180C/G and rs3745369 sites. In a haplotype analysis, the occurrence rate of the haplotype AGGCAGC was 1.97 times (P<0.05) higher in the patient group than in the control group. In addition, the numbers of GG genotype carriers of rs3219175 and rs3486119 in the middle-aged male CI patients and the middle-aged small artery occlusion (SAO) CI patients were higher than those in the control group (P<0.05). In the Chinese Han middle-aged population, the GG gene type carriers of the resistin gene sites rs3219175 and rs34861192 had a high risk for CI onset, especially in middle-aged male patients and SAO CI in all middle-aged patients.

Secret talk between adipose tissue and central nervous system via secreted factors-an emerging frontier in the neurodegenerative research

First seen as a storage organ, the white adipose tissue (WAT) is now considered as an endocrine organ. WAT can produce an array of bioactive factors known as adipokines acting at physiological level and playing a vital role in energy metabolism as well as in immune response. The global effect of adipokines in metabolic activities is well established, but their impact on the physiology and the pathophysiology of the central nervous system (CNS) remains poorly defined. Adipokines are not only produced by the WAT but can also be expressed in the CNS where receptors for these factors are present. When produced in periphery and to affect the CNS, these factors may either cross the blood brain barrier (BBB) or modify the BBB physiology by acting on cells forming the BBB. Adipokines could regulate neuroinflammation and oxidative stress which are two major physiological processes involved in neurodegeneration and are associated with many chronic neurodegenerative diseases. In this review, we focus on four important adipokines (leptin, resistin, adiponectin, and TNFα) and one lipokine (lysophosphatidic acid-LPA) associated with autotaxin, its producing enzyme. Their potential effects on neurodegeneration and brain repair (neurogenesis) will be discussed. Understanding and regulating these adipokines could be an interesting lead to novel therapeutic strategy in order to counteract neurodegenerative disorders and/or promote brain repair.

Angiopoietin-like protein 4 serum levels and gene polymorphisms are associated with large artery atherosclerotic stroke

BACKGROUND

Angiopoietin-like protein 4 (ANGPTL4) is a central player in lipid metabolism and atherosclerosis and may thus be involved in ischaemic stroke. However, no study in humans has investigated the association of ANGPTL4 gene polymorphisms or serum levels with ischaemic stroke.

METHODS

We investigated the influence of the tagged single nucleotide polymorphisms (tSNPs) rs4076317 (c.207C>G) and rs1044250 (c.797C>T; T266M) of the ANGPTL4 gene on ischaemic stroke risk in a large group of 712 large artery atherosclerotic (LAA) stroke patients and 828 controls. In addition, we examined the association of the serum ANGPTL4 levels with lipid metabolism, LAA stroke severity and ischaemic volume in a sample of 302 LAA stroke patients and 307 controls.

RESULTS

The findings reveal that rs4076317 exerts a co-dominant effect on lower serum TG levels compared with common homozygotes. Fewer stroke cases were homozygous for variants of rs4076317 compared with the controls (7.0% vs. 10.9%). The serum ANGPTL4 levels in patients were significantly higher than those in the controls in a univariate manner (P=0.001) and after adjustment for other risk factors (1.463 [1.215-1.835]; P<0.001). Consistently, the ANGPTL4 levels were statistically correlated with higher NIHSS scores (r=0.172, P=0.003) and larger lesion volumes (r=0.124, P=0.031).

CONCLUSION

We concluded that the tagged SNPs and high serum levels of ANGPTL4 are associated with LAA stroke and the lipid characteristics.

Expression of angiopoietin-like protein 4 at the fracture site: Regulation by hypoxia and osteoblastic differentiation

Vascular disruption that occurs as a consequence of bone fracture, leads to hypoxia at the site of damage. Hypoxia regulates the expression of a number of genes that can modulate energy conservation, cell survival, tissue regeneration and angiogenesis. In this study we investigated the expression of Angiopoietin-like 4, an adipocytokine that has additional roles in angiogenesis, at the fracture site. We demonstrate that Angptl4 mRNA expression increased early during fracture healing (day 3) returning close to baseline at day14. In the callus, Angptl4 mRNA was visualized in areas of condensing mesenchymal cells, callus cartilage and was especially high in mineralizing osteoblasts located in areas of new bone formation. In vitro, Angptl4 mRNA expression in osteoblasts increased under hypoxic conditions and in cells treated with the hypoxia mimetic desferrioxamine. Angptl4 levels were strongly induced at day 14 in differentiating MC3T3-E1 osteoblastic cells. Exogenous ANGPTL4 increased expression of Runx2, Spp1, vegfa, and Alp mRNA in differentiating osteoblasts. We suggest that the distribution of Angptl4 in the callus may be driven by hypoxia and that Angptl4 may play a role in osteoblastic differentiation, and possibly angiogenesis via regulation of VEGF. Further studies could reveal a dual role for Angptl4 in angiogenesis and osteogenesis.

Chronic intermittent hypoxia leads to insulin resistance and impaired glucose tolerance through dysregulation of adipokines in non-obese rats

BACKGROUND AND OBJECTIVES

The aim of this study was to determine whether chronic intermittent hypoxia (CIH) could affect the secretion of adipokines, such as resistin, leptin, and adiponectin, in non-obese rats and to investigate the potential mechanisms.

METHODS

An established rodent model of CIH was utilized, in which rats were exposed to varying oxygen levels (7-21 %) respectively over a period of 5 weeks. The area under the curve (AUCG) and the insulin resistance index (homeostasis model of assessment for insulin resistance index, HOMA-IR) were calculated. The levels of several secretory factors in the blood were measured by enzyme-linked immunosorbent assay (ELISA). The mRNA levels and protein expression in adipose tissues was measured by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Glucose tolerance and the levels of adiponectin in non-obese rats were decreased in the CIH group both in the serum and adipose tissue compared with the controls, while the insulin resistance index and the levels of resistin and leptin were increased. Moreover, the expressions of hypoxia inducible factor-1α and lactate dehydrogenase A were significantly higher in chronic intermittent hypoxia rats than in control rats, suggesting the presence of adipose tissue hypoxia.

CONCLUSIONS

These results show that CIH leads to insulin resistance (IR) and impaired glucose tolerance (IGT) in a non-obese rodent model of obstructive sleep apnea-hypopnea syndrome, and these effects may be due to the dysregulation of adiponectin, resistin, and leptin.

Acute-Phase Protein α1-Antitrypsin—A Novel Regulator of Angiopoietin-like Protein 4 Transcription and Secretion

The angiopoietin-like protein 4 (angptl4, also known as peroxisome proliferator–activated receptor [PPAR]γ–induced angiopoietin-related protein) is a multifunctional protein associated with acute-phase response. The mechanisms accounting for the increase in angptl4 expression are largely unknown. This study shows that human α1-antitrypsin (A1AT) upregulates expression and release of angplt4 in human blood adherent mononuclear cells and in primary human lung microvascular endothelial cells in a concentration- and time-dependent manner. Mononuclear cells treated for 1 h with A1AT (from 0.1 to 4 mg/ml) increased mRNA of angptl4 from 2- to 174-fold, respectively, relative to controls. In endothelial cells, the maximal effect on angptl4 expression was achieved at 8 h with 2 mg/ml A1AT (11-fold induction versus controls). In 10 emphysema patients receiving A1AT therapy (Prolastin), plasma angptl4 levels were higher relative to patients without therapy (nanograms per milliliter, mean [95% confidence interval] 127.1 [99.5–154.6] versus 76.8 [54.8–98.8], respectively, p = 0.045) and correlated with A1AT levels. The effect of A1AT on angptl4 expression was significantly diminished in cells pretreated with a specific inhibitor of ERK1/2 activation (UO126), irreversible and selective PPARγ antagonist (GW9662), or genistein, a ligand for PPARγ. GW9662 did not alter the ability of A1AT to induce ERK1/2 phosphorylation, suggesting that PPARγ is a critical mediator in the A1AT-driven angptl4 expression. In contrast, the forced accumulation of HIF-1α, an upregulator of angptl4 expression, enhanced the effect of A1AT. Thus, acute-phase protein A1AT is a physiological regulator of angptl4, another acute-phase protein.

Effects of antidepressant drug exposure on gene expression in the developing cerebral cortex

To clarify the basis of limited responses in children and adolescents to antidepressant treatments considered standard in the treatment of adult major depressive disorder, juvenile Sprague-Dawley rats were subjected to 21-day treatment with dissimilar antidepressant drugs fluoxetine, imipramine, or vehicle control. Total RNA was extracted from brain frontal cortices and hybridized to the Affymetrix 230.2 chip. A total of 18 microarrays were analyzed (i.e., six biological replicates in three treatment groups). Transcripts identified were validated using Taqman real-time quantitative PCR methodology, and the relative expression of each gene was also determined. In both the imipramine- and fluoxetine-treated animals, expression of six genes was down-regulated (ANOVA-filtered gene expression data using dChip [version 2005]): Gpd1; Lrrn3; Sult1A1; Angptl4; Mt1a; Unknown. Furthermore, four genes were over-expressed: P4Ha1; RDG1311476; Rgc32; and SLC25A18-like by both imipramine and fluoxetine. These data demonstrate that antidepressant drugs interfere with the expression of genes involved in cell signaling, survival, and protein metabolism. Our results show that antidepressants regulate the induction of highly specific transcriptional programs in the developing frontal cortex. These findings provide novel insights into the long-term molecular actions of antidepressant drugs in the developing brain.

Alterations in mouse hypothalamic adipokine gene expression and leptin signaling following chronic spinal cord injury and with advanced age

Chronic spinal cord injury (SCI) results in an accelerated trajectory of several cardiovascular disease (CVD) risk factors and related aging characteristics, however the molecular mechanisms that are activated have not been explored. Adipokines and leptin signaling are known to play a critical role in neuro-endocrine regulation of energy metabolism, and are now implicated in central inflammatory processes associated with CVD. Here, we examine hypothalamic adipokine gene expression and leptin signaling in response to chronic spinal cord injury and with advanced age. We demonstrate significant changes in fasting-induced adipose factor (FIAF), resistin (Rstn), long-form leptin receptor (LepRb) and suppressor of cytokine-3 (SOCS3) gene expression following chronic SCI and with advanced age. LepRb and Jak2/stat3 signaling is significantly decreased and the leptin signaling inhibitor SOCS3 is significantly elevated with chronic SCI and advanced age. In addition, we investigate endoplasmic reticulum (ER) stress and activation of the uncoupled protein response (UPR) as a biological hallmark of leptin resistance. We observe the activation of the ER stress/UPR proteins IRE1, PERK, and eIF2alpha, demonstrating leptin resistance in chronic SCI and with advanced age. These findings provide evidence for adipokine-mediated inflammatory responses and leptin resistance as contributing to neuro-endocrine dysfunction and CVD risk following SCI and with advanced age. Understanding the underlying mechanisms contributing to SCI and age related CVD may provide insight that will help direct specific therapeutic interventions.

Protection Against Myocardial Infarction and No-Reflow Through Preservation of Vascular Integrity by Angiopoietin-Like 4

Background—

Increased permeability, predominantly controlled by endothelial junction stability, is an early event in the deterioration of vascular integrity in ischemic disorders. Hemorrhage, edema, and inflammation are the main features of reperfusion injuries, as observed in acute myocardial infarction (AMI). Thus, preservation of vascular integrity is fundamental in ischemic heart disease. Angiopoietins are pivotal modulators of cell–cell junctions and vascular integrity. We hypothesized that hypoxic induction of angiopoietin-like protein 4 (ANGPTL4) might modulate vascular damage, infarct size, and no-reflow during AMI.

Methods and Results—

We showed that vascular permeability, hemorrhage, edema, inflammation, and infarct severity were increased in angptl4 -deficient mice. We determined that decrease in vascular endothelial growth factor receptor 2 (VEGFR2) and VE-cadherin expression and increase in Src kinase phosphorylation downstream of VEGFR2 were accentuated after ischemia-reperfusion in the coronary microcirculation of angptl4 -deficient mice. Both events led to altered VEGFR2/VE-cadherin complexes and to disrupted adherens junctions in the endothelial cells of angptl4 -deficient mice that correlated with increased no-reflow. In vivo injection of recombinant human ANGPTL4 protected VEGF-driven dissociation of the VEGFR2/VE-cadherin complex, reduced myocardial infarct size, and the extent of no-reflow in mice and rabbits.

Conclusions—

These data showed that ANGPTL4 might constitute a relevant target for therapeutic vasculoprotection aimed at counteracting the effects of VEGF, thus being crucial for preventing no-reflow and conferring secondary cardioprotection during AMI.

Angiopoietin-like 4: a decade of research

The past decade has seen a rapid development and increasing recognition of ANGPTL4 (angiopoietin-like 4) as a remarkably multifaceted protein that is involved in many metabolic and non-metabolic conditions. ANGPTL4 has been recognised as a central player in various aspects of energy homoeostasis, at least in part, via the inhibitory interaction between the coiled-coil domain of ANGPTL4 and LPL (lipoprotein lipase). The fibrinogen-like domain of ANGPTL4 interacts and activates specific integrins to facilitate wound healing, modulates vascular permeability, and regulates ROS (reactive oxygen species) level to promote tumorigenesis. The present review summarizes these landmark findings about ANGPTL4 and highlights several important implications for future clinical practice. Importantly, these implications have also raised many questions that are in urgent need of further investigations, particularly the transcription regulation of ANGPTL4 expression, and the post-translation cleavage and modifications of ANGPTL4. The research findings over the past decade have laid the foundation for a better mechanistic understanding of the new scientific discoveries on the diverse roles of ANGPTL4.

Resistin is associated with mortality in patients with traumatic brain injury

INTRODUCTION

Recently, we reported that high levels of resistin are present in the peripheral blood of patients with intracerebral hemorrhage and are associated with a poor outcome. However, not much is known regarding the change in plasma resistin and its relation with mortality after traumatic brain injury (TBI). Thus, we sought to investigate change in plasma resistin level after TBI and to evaluate its relation with disease outcome.

METHODS

Fifty healthy controls and 94 patients with acute severe TBI were included. Plasma samples were obtained on admission and at days 1, 2, 3, 5 and 7 after TBI. Its concentration was measured by enzyme-linked immunosorbent assay.

RESULTS

Twenty-six patients (27.7%) died from TBI within 1 month. After TBI, plasma resistin level in patients increased during the 6-hour period immediately after TBI, peaked within 24 hours, plateaued at day 2, decreased gradually thereafter and was substantially higher than that in healthy controls during the 7-day period. A forward stepwise logistic regression selected plasma resistin level (odds ratio, 1.107; 95% confidence interval, 1.014-1.208; P = 0.023) as an independent predictor for 1-month mortality of patients. A multivariate linear regression showed that plasma resistin level was negatively associated with Glasgow Coma Scale score (t = -6.567, P < 0.001). A receiver operating characteristic curve identified plasma resistin cutoff level (30.8 ng/mL) that predicted 1-month mortality with the optimal sensitivity (84.6%) and specificity (75.0%) values (area under curve, 0.854; 95% confidence interval, 0.766-0.918; P < 0.001).

CONCLUSIONS

Increased plasma resistin level is found and associated with Glasgow Coma Scale score and mortality after TBI.

Tissue-specific effects of valsartan on rstn and fiaf gene expression in the ob/ob mouse

The RAS is a novel target in the study of diabetes, and clinical trials have indicated that ARBs, such as valsartan, may exert some of their clinical effects through an influence on adipose tissue. We studied the effect of valsartan on adipokine genes resistin (rstn) and fasting-induced adipose factor (fiaf) using obese and diabetic ob/ob mice. In addition to visceral and subcutaneous fat, rstn and fiaf mRNA levels were also measured in several other tissues known to express these adipokines, including the pituitary, cerebral cortex and hypothalamus. The significant findings were that (a) fiaf gene expression was elevated two- to fourfold in visceral and subcutaneous fat from ob/ob mice, compared with lean controls; (b) the increase in fiaf mRNA in subcutaneous, but not visceral, fat from ob/ob mice was returned to lean control levels following 2 weeks of valsartan treatment; (c) fiaf expression was reduced in the hypothalamus, but not in the cortex or pituitary, of ob/ob mice; (d) rstn expression was greatly reduced in visceral fat from ob/ob mice, compared with lean controls, but this was unaffected by valsartan; and (e) rstn expression was unchanged in all other tissues from ob/ob mice, with or without valsartan treatment.

Modulation of plasma TG lipolysis by Angiopoietin-like proteins and GPIHBP1

There is evidence that elevated plasma triglycerides (TG) serve as an independent risk factor for coronary heart disease. Plasma TG levels are determined by the balance between the rate of production of chylomicrons and VLDL in intestine and liver, respectively, and their rate of clearance in peripheral tissues. Lipolytic processing of TG-rich lipoproteins is mediated by the enzyme lipoprotein lipase (LPL), which is tethered to the capillary endothelium via heparin sulphate proteoglycans. In recent years the Angiopoietin-like proteins ANGPTL3 and ANGPTL4 have emerged as novel modulators of LPL activity. Studies in transgenic animals supported by in vitro experiments have demonstrated that ANGPTL3 and ANGPTL4 impair plasma TG clearance by inhibiting LPL activity. In humans, genetic variation within the ANGPTL3 and ANGPTL4 genes contributes to variation in plasma TG and HDL levels, thereby validating the importance of ANGPTLs in the regulation of lipoprotein metabolism in humans. Combined with the discovery of GPIHBP1 as a likely LPL anchor, these findings have led to a readjustment of the mechanism of LPL function. This review provides an overview of our current understanding of the role and regulation of ANGPTL3, ANGPTL4 and GPIHBP1, and places the newly acquired knowledge in the context of the established function and mechanism of LPL-mediated lipolysis.

Lipopolysaccharide (LPS) stimulates adipokine and socs3 gene expression in mouse brain and pituitary gland in vivo, and in N-1 hypothalamic neurons in vitro

Adipokines that modulate metabolic and inflammatory responses, such as resistin (rstn) and fasting-induced adipose factor (fiaf), are also expressed in mouse brain and pituitary gland. Since lipopolysaccharide (LPS)-induced endotoxinemia provokes an anorectic response via a hypothalamic-dependent mechanism we hypothesized that LPS would also modify hypothalamic adipokine expression. Challenging male CD-1 mice with LPS (5 mg/kg; s.c.) significantly reduced bodyweight (24 h) and realtime RT-PCR revealed time- and tissue-dependent increases in rstn, fiaf and suppressor of cytokine signaling-3 (socs-3) mRNA in hypothalamic, pituitary, cortical and adipose tissues. Gene expression was rapidly increased (3-6 h) in the hypothalamus and pituitary, but returned to normal within 24 h. In contrast, with the exception of rstn in fat, the expression of target genes remained elevated in cortex and visceral fat at 24 h post-injection. In order to more specifically examine the hypothalamic response to LPS we investigated its effects directly on N-1 hypothalamic neurons in vitro. LPS (25 microg/mL; 3 h) had no effect on rstn mRNA, but significantly stimulated fiaf and socs-3 expression. Although various toll-like receptor 4 (TLR4) antagonists (parthenolide, PD098059, and SB202190) did not prevent the LPS-induced increases in fiaf and socs-3, they did partially attenuate its stimulatory effects. We conclude that LPS treatment increases the expression of central, and possibly neuronal, adipokine genes which may influence local tissue repair and function, but could also have downstream consequences on the hypothalamic control of appetite and energy metabolism following an inflammatory insult.

Host biomarkers and biological pathways that are associated with the expression of experimental cerebral malaria in mice

Cerebral malaria (CM) is a primary cause of malaria-associated deaths among young African children. Yet no diagnostic tools are available that could be used to predict which of the children infected with Plasmodium falciparum malaria will progress to CM. We used the Plasmodium berghei ANKA murine model of experimental cerebral malaria (ECM) and high-density oligonucleotide microarray analyses to identify host molecules that are strongly associated with the clinical symptoms of ECM. Comparative expression analyses were performed with C57BL/6 mice, which have an ECM-susceptible phenotype, and with mice that have ECM-resistant phenotypes: CD8 knockout and perforin knockout mice on the C57BL/6 background and BALB/c mice. These analyses allowed the identification of more than 200 host molecules (a majority of which had not been identified previously) with altered expression patterns in the brain that are strongly associated with the manifestation of ECM. Among these host molecules, brain samples from mice with ECM expressed significantly higher levels of p21, metallothionein, and hemoglobin alpha1 proteins by Western blot analysis than mice unaffected by ECM, suggesting the possible utility of these molecules as prognostic biomarkers of CM in humans. We suggest that the higher expression of hemoglobin alpha1 in the brain may be associated with ECM and could be a source of excess heme, a molecule that is considered to trigger the pathogenesis of CM. Our studies greatly enhance the repertoire of host molecules for use as diagnostics and novel therapeutics in CM.

Traumatic brain injury induces adipokine gene expression in rat brain

Traumatic brain injury (TBI) induces cachexia and neuroinflammation which profoundly impact patient recovery. Adipokine genes such as leptin (ob), resistin (rstn) and fasting-induced adipose factor (fiaf) are implicated in energy metabolism and body weight control and are also associated with chronic low grade inflammation. Since central rstn and fiaf expression was increased following hypoxic/ischemic brain injury, we hypothesized that these genes would also be induced in the rat brain following TBI. Realtime RT-PCR detected a 2-2.5-fold increase in ob mRNA in the ipsilateral cortex and thalamus 12h following lateral fluid percussion (FP)-induced brain injury. Fiaf mRNA was elevated 5-7.5-fold in cortex, hippocampus and thalamus, and modest increases were also detectable in the contralateral brain. Remarkably, rstn mRNA was elevated in ipsilateral (150-fold) and in contralateral (50-fold) hippocampus. To test whether these changes were part of an inflammatory response to TBI we also examined the effects of an intracerebral injection of lipopolysaccharide (LPS). We determined that central injection of LPS produced some, but not all, of the changes seen after TBI. For example, in contrast to the stimulatory influence of TBI, LPS had no effect on ob expression in any brain region, though fiaf and rstn mRNA levels were significantly elevated in both ipsi- and contralateral cortex.

IN CONCLUSION

(a) brain-derived adipokines could be involved in the acute pathology of traumatic brain injury partly through modulation of central inflammatory responses, but also via leptin-mediated neuroprotective effects and (b) TBI-induced brain adipokines may induce the metabolic changes observed following neurotrauma.

Study of Resistin gene expression in peripheral blood mononuclear cell and its gene polymorphism in a small range population

OBJECTIVE

To observe the expression of Resistin mRNA in peripheral blood mononuclear cells and its gene polymorphism in coding region in a small range population in Zhejiang Province of China.

METHODS

Eighty-three cases of type 2 diabetes mellitus and 53 healthy people were included. The expression of Resistin mRNA in peripheral blood mononuclear cells was detected by RT-PCR and semi-quantitative PCR assay. The sequencing work was done in Resistin cDNA and gene polymorphism was analyzed.

RESULTS

At the same condition, in 83 diabetes patients, Resistin mRNA was detected in 23 cases (11 males and 12 females). There was no Resistin mRNA expression in 53 healthy people. The ratio of PCR products between Resistin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was from 0.564 to 1.238, averaging 0.804+/-0.436. The sequence of Resistin cDNA is almost identical with each other and with that in GenBank with no single nucleotide polymorphism being found.

CONCLUSION

Resistin mRNA is expressed in human peripheral blood mononuclear cells in some type 2 diabetes mellitus, but its expression is at a low level. Among the experiment population we did not find polymorphism phenomenon in Resistin coding region. The different individual's Resistin coding region is highly coincident.

Adipokine gene expression in a novel hypothalamic neuronal cell line: resistin-dependent regulation of fasting-induced adipose factor and SOCS-3

Adipokines such as leptin, resistin, and fasting-induced adipose factor (FIAF) are secreted by adipocytes, but their expression is also detectable in the brain and pituitary. The role of central adipokines remains elusive, but we speculate that they may modulate those hypothalamic signaling pathways that control energy homeostasis. Here we describe experiments to test this in which we exploited a novel hypothalamic neuronal cell line (N-1) that expresses a variety of neuropeptides and receptors that are known to be implicated in appetite regulation. Using real-time RT-PCR, we confirmed that N-1 neurons express resistin (rstn) and fiaf, as well as suppressor of cytokine signaling-3 (socs-3), a feedback inhibitor of leptin signaling. Treating N-1 cells with recombinant resistin (200 ng/ml, 30 min) reduced both fiaf (25%, p < 0.005) and socs-3 (29%, p < 0.005) mRNA levels, and similar reductions in fiaf (40%, p < 0.001) and socs-3 (25%, p < 0.001) resulted following the overexpression of resistin. Conversely, when RNA interference (RNAi) was used to reduce endogenous rstn levels (-60%, p < 0.005), fiaf and socs-3 expression was increased (46 and 65% respectively, p < 0.005). A similar reduction in rstn mRNA was achieved using RNAi in differentiated 3T3-L1 adipocytes, and this manipulation also reduced fiaf and socs-3 expression (-53, -21 and -20% respectively, p < 0.005). In contrast, although RNAi successfully reduced fiaf mRNA by 50% (p < 0.001) in N-1 cells and 40% (p < 0.001) in 3T3-L1 cells, there was no effect on rstn or socs-3 mRNA. These data suggest that resistin exerts a novel autocrine/paracrine control over fiaf and socs-3 expression in both 3T3-L1 adipocytes and N-1 neurons. Such a mechanism could be part of the central feedback system that modulates the effects of adipokines, and other adiposity signals, implicated in hypothalamic energy homeostasis. However, it remains to be determined whether these in vitro results can be translated to the control of adipokine expression in brain and adipose tissue.

Adipokine gene expression in brain and pituitary gland

The brain has been recognized as a prominent site of peptide biosynthesis for more than 30 years, and many neuropeptides are now known to be common to gut and brain. With these precedents in mind it is remarkable that adipose-derived peptides like leptin have attracted minimal attention as brain-derived putative neuromodulators of energy balance. This review outlines the evidence that several adipose-specific genes are also expressed in the central nervous system and pituitary gland. We, and others, confirmed that the genes for leptin, resistin, adiponectin, FIAF (fasting-induced adipose factor) and adiponutrin are expressed and regulated in these tissues. For example, leptin mRNA was readily detectable in human, rat, sheep and pig brain, but not in the mouse. Leptin expression in rat brain and pituitary was regulated through development, by food restriction, and following traumatic brain injury. In contrast, hypothalamic resistin mRNA was unaffected by age or by fasting, but was significantly depleted by food restriction in mouse pituitary gland. Similar results were seen in the ob/ob mouse, and we noted a marked reduction in resistin-positive hypothalamic nerve fibres. Resistin and fiaf mRNA were also upregulated in hypoxic/ischaemic mouse brain. Our studies on the regulation of neuronal adipokines were greatly aided by the availability of clonal hypothalamic neuronal cell lines. One of these, N-1, expresses both rstn and fiaf together with several other neuropeptides and receptors involved in energy homeostasis. Selective silencing of rstn revealed an autocrine/paracrine regulatory system, mediated through socs-3 expression that may influence the feedback effects of insulin and leptin in vivo. A similar convergence of signals in the pituitary gland could also influence anterior pituitary hormone secretion. In conclusion, the evidence is suggestive that brain and pituitary-derived adipokines represent a local regulatory circuit that may fine tune the feedback effects of adipose hormones in the control of energy balance.