pre-B Cell Colony-enhancing Factor Research Articles

Liver X Receptor (LXR) activation negatively regulates visfatin expression in macrophages

Adipose tissue macrophages (ATM) are the major source of visfatin, a visceral fat adipokine upregulated during obesity. Also known to play a role in B cell differentiation (pre-B cell colony-enhancing factor (PBEF)) and NAD biosynthesis (nicotinamide phosphoribosyl transferase (NAMPT)), visfatin has been suggested to play a role in inflammation.Liver X Receptor (LXR) and Peroxisome Proliferator-Activated Receptor (PPAR)γ are nuclear receptors expressed in macrophages controlling the inflammatory response. Recently, we reported visfatin as a PPARγ target gene in human macrophages. In this study, we examined whether LXR regulates macrophage visfatin expression. Synthetic LXR ligands decreased visfatin gene expression in a LXR-dependent manner in human and murine macrophages. The decrease of visfatin mRNA was paralleled by a decrease of protein secretion. Consequently, a modest and transient decrease of NAD+ concentration was observed. Interestingly, LXR activation decreased the PPARγ-induced visfatin gene and protein secretion in human macrophages.Our results identify visfatin as a gene oppositely regulated by the LXR and PPARγ pathways in human macrophages.

Circulating and local visfatin/Nampt/PBEF levels in spontaneously hypertensive rats, stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats

Visfatin (also known as nicotinamide phosphoribosyltransferase and pre-B cell colony-enhancing factor) is a multifunctional protein. Visfatin has been reported to be involved in several biological processes in the cardiovascular system, . However, the role of visfatin in hypertension is still unclear. In this study, we examined the circulating and local adipose visfatin levels in spontaneously hypertensive rats (SHR), stroke-prone spontaneously hypertensive rats (SHR-SP), and in their normotensive control Wistar-Kyoto (WKY). SHR and SHR-SP rats exhibited lower body weight, lower fat tissue and hypolipidemia. No differences of serum visfatin levels were observed in SHR/SHR-SP and WKY. Serum visfatin levels did not correlate to serum glucose, lipids, insulin, and fat pad weights, but significantly correlated to weights of skeletal muscle. Visfatin expression in visceral fat tissue was slightly lower in SHR-SP compared with that in WKY. Moreover, there were no significant differences of visfatin expression in skeletal muscles among WKY, SHR and SHR-SP. Finally, visfatin protein was detected in L6 rat skeletal muscle cell culture medium, indicating that visfatin was secreted from skeletal muscle cells. Thus, our results may provide useful information for understanding the characteristic of visfatin in hypertensive models, and support the view that visfatin may be a myokine.

Stretch and inflammation-induced Pre-B cell colony-enhancing factor (PBEF/Visfatin) and Interleukin-8 in amniotic epithelial cells

Preterm birth continues to be a growing problem in the USA. Although approximately half of preterm births are caused by intrauterine infection, uterine over-distension is also a cause. In this study we have compared the effects of static stretch, cyclic stretch/release and an inflammatory stimulus alone and in combination on the expression of Pre-B cell colony-enhancing factor (PBEF) and IL-8 in primary amniotic epithelial cells (AEC). We then sought to identify some of the mechanism(s) by which these cells respond to stretching stimuli. We show that cyclic stretch/release is a more robust stimulus for both PBEF and IL-8 than static stretch. Cyclic stretch/release increased both intracellular and secreted PBEF and a combination of both types of stretch was a more robust stimulus to PBEF that IL-8. However, when an inflammatory stimulus (IL-1β) was added to either kind of stretch, the effect on IL-8 was much greater than that on PBEF. Thus, different kinds of stretch affect the expression of these two cytokines from AEC, but inflammation is a much stronger stimulus of IL-8 than PBEF, agreeing with its primary role as a chemokine. Although the AEC showed morphological signs of increased cellular stress during stretching, blocking reactive oxygen species (ROS) had little effect. However, blocking integrin binding to fibronectin significantly reduced the responses of both PBEF and IL-8 to cyclic stretch/release. The increased PBEF, both intracellularly and secreted, suggests that it functions both to increase the metabolism of the cells, at the same time as stimulating further the cytokine cascade leading to parturition.

Visfatin is upregulated in type-2 diabetic rats and targets renal cells

Visfatin (also known as pre-B cell colony-enhancing factor) is a newly discovered adipocytokine that is preferentially produced by visceral fat and regulated by cytokines promoting insulin resistance. Here we determined its renal synthesis and physiology in a genetic model of type 2 diabetes in rats. These rats had higher levels of visfatin synthesis in both glomeruli and tubulointerstitium compared to control rats. Plasma visfatin levels were significantly increased in the early stages of diabetic nephropathy and positively correlated with body weight, fasting plasma glucose, and microalbuminuria. Interestingly, visfatin synthesis was found to occur in podocytes and proximal tubular cells, as well as in adipocytes in vitro. Further, in both renal cells, visfatin synthesis was significantly increased by high glucose in the media but not by angiotensin II. Additionally, visfatin treatment induced rapid uptake of glucose and was associated with increased translocation of GLUT-1 to the cellular membrane of both renal cell types. Furthermore, visfatin induced tyrosine phosphorylation of the insulin receptor, activated downstream insulin signaling pathways such as Erk-1, Akt, and p38 MAPK, and markedly increased the levels of TGFbeta1, PAI-1, type I collagen, and MCP-1 in both renal cells. Thus, our results suggest that visfatin is produced by renal cells and has an important paracrine role in the pathogenesis of diabetic nephropathy.

Pre-B Cell Colony Enhancing Factor/NAMPT/Visfatin in Inflammation and Obesity- Related Disorders

Whereas prototypic adipocytokines such as adiponectin or leptin are mainly derived from adipocytes, others such as pre-B cell colony enhancing factor (PBEF)/nicotinamide phosphoribosyl transferase (NAMPT)/visfatin or resistin are produced by various cell types throughout the body. Although first discovery of this molecule as PBEF suggested primarily a cytokine function, its rediscovery as the key enzyme in nicotinamide adenine dinucleotide (NAD) generation has considerably widened its biological perspective. Finally, the same molecule was introduced as visfatin claiming an insulin-mimetic effect which has been questioned. Both extracellular (cytokinelike) and intracellular (enzymatic) functions are responsible for its relevance in immune, metabolic and stress responses. Its cytokine functions are mainly pro-inflammatory as it induces potently various other pro-inflammatory cytokines such as tumor necrosis factor alpha (TNFa) or interleukin-6 (IL-6). Its intracellular functions concentrate on the regulation of the activity of NAD-consuming enzymes such as various sirtuins thereby also affecting (TNFa) biosynthesis, cell life-span and longevity. Biochemical neutralization of PBEF/NAMPT/visfatin has been proven effective in various models of inflammation including sepsis/arthritis and in various models of cancer. Patients with non-alcoholic fatty liver disease (NAFLD) exhibit increased serum concentrations of PBEF/Nampt/visfatin and weight loss is associated both with a decrease in serum levels and reduced liver expression. Many of the biological functions of this "cytokine-enzyme" have been characterized in the last years, however, its definite role in various metabolic, inflammatory and malignant diseases has yet to be defined.

Neuronal Protective Role of PBEF in a Mouse Model of Cerebral Ischemia

Pre-B-cell colony-enhancing factor (PBEF) (also known as nicotinamide phosphoribosyltransferase) is a rate-limiting enzyme in the salvage pathway for mammalian biosynthesis of nicotinamide adenine dinucleotide (NAD(+)). By synthesizing NAD(+), PBEF functions to maintain an energy supply that has critical roles in cell survival. Cerebral ischemia is a major neural disorder with a high percentage of mortality and disability. Ischemia leads to energy depletion and eventually neuronal death and brain damage. This study investigated the role of PBEF in cerebral ischemia using a photothrombosis mouse model. Using immunostaining, we initially determined that PBEF is highly expressed in neurons, but not in glial cells in the mouse brain. To study the role of PBEF in ischemia in vivo, we used PBEF knockout heterozygous (Pbef+/-) mice. We showed that these mice have lower PBEF expression and NAD(+) level than do wild-type (WT) mice. When subjected to photothrombosis, Pbef+/- mice have significantly larger infarct volume than do age-matched WT mice at 24 hours after ischemia. Higher density of degenerating neurons was detected in the penumbra of Pbef+/- mice than in WT mice using Fluoro-Jade B staining. Our study shows that PBEF has a neuronal protective role in cerebral ischemia presumably through enhanced energy metabolism.

Novel role of Pre‐B‐Cell Colony Enhancing Factor (PBEF) in pulmonary arterial hypertension (PAH)

The discovery of novel mediators in PAH allows for novel insights into PAH pathobiology and identification of therapeutic targets. PBMC expression profiles from 7 PAH patients (49±7 years, mPAP 55±18 mmHg, PVR 14±11 U) and 10 healthy controls (45±7 years) identified 224 differentially expressed genes including PBEF as an upregulated gene in PAH. We previously identified PBEF as a mediator in lung injury, with extracellular proinflammatory cytokine‐like activity and intracellular enzymatic activity regulating NAD levels, cell redox state, histone deacetylases and inhibiting apoptosis. Plasma PBEF levels were higher in PAH patients (n=10, 46±17 years, mPAP 56±18 mmHg, PVR 10±4 U) than controls (n=9, 33±7 years), (5000±2000 vs. 7500 ± 3000 pg/ml; P=0.04) and trended with BNP levels (R=0.6, P=0.08) and inversely with 6‐minute walk distance (R=−0.57, P=0.08). Immunohistochemistry in explanted PAH lungs (n=3) revealed significant PBEF expression in plexiform lesions and in remodeled PAs, without PBEF staining in PAs of controls. Finally, compared to WT control mice, PBEF heterozygous mice (PBEF+/−) developed less severe PH (FIO2=10% and SU5416 for 3 weeks) with less significant elevations in RVSP (PBEF+/+ 19 ± 2 vs. PBEF+/− 12 ± 4 mmHg, P=0.03) and less RVH (RV/LV+S: PBEF+/+ 0.44 ± 0.05 vs. PBEF+/− 0.34 ± 0.08, P=0.06). Our results implicate PBEF as a novel biomarker and therapeutic target in PAH.

The early responses of PBEF in acute lung injury

Objective To investigate the early responses and roles of Pre-B-cell colony-enhancing factor (PBEF)during acute lung injury(au)induced by seawater-immersion after open chest trauma.Method Sixteen dogs randomly divided(random number)into seawater group(SG)and control group(CG).Blood samples were collected at 0,2,4,6,8 h after Irauma.Broncho-alveolar lavage fluid(BALF)and lung tissue were collected at 8 h after trauma.The levels of inflammatory cytokines(IL-1β,IL-8 and vWF)in the plasma and PBEF in the plasma,BALF and lung tissue were measured with ELISA Kit.The plasma osmotic pressue,electrolyte concentralion from plasma and total protein concentration from BALF and plasma were measured.And then,the correlations among the PBEF,plasma osmotic pressue,and inflammatory cytokines were analyzed.All data were analyzed by SPSS 10.0 software.Results ComparedwithCG,the levels of PBEFfrom the plasm,BALF and hmg tissue at 8 h after trauma were significantly increased inSG,P＜0.O1[in plasma:(3014.16±883.47)vs.(1060.94±251.08);in BALF:(1373.35±102.53)vs.(997.77±70.31);in lung tissue:(1455.22±71.74)vs.(921.43±118.13),pg/mL];The peak of the levels of PBEF in the plasma were significant different both occuring timing(4 h vs.6 h)and values[(3204.56±604.21)vs.(1220.86±191.30)]between inSGand CG(P＜0.05).IL-1β,IL-8 and vWF from the plasma showed same changes.Significant correlations were observed between the level of PBEF and PPI,the level of PBEF and plasma osmotic pressure.The correlation coefficients were 0.489(PBEF vs.PPI),0.549(PBEF vs.IL-1β),0.496(PBEF vs.IL-8),O.465(PBEF vs.vWf),respectively.Conclusions These results indicated that PBEF was one of the major inflammatory cytokines released in the early phase of acute lung injury induced by seawater-immersion after open chest trauma,and played an important role in the development of it.Monitoring the hvels of PBEF may offer a significant information to predict the ALI. Key words: Acute lung injury(au); Pre-B-cell colony-enhancing factor(PBEF); Open chest trauma; Seawater; Immersion; Cytokines

242: Pre-B-Cell Colony Enhancing Factor (PBEF) Is a Novel target in Hypoxia-Induced Murine Pulmonary Hypertension

Pulmonary arterial hypertension (PAH) is characterized by significant and aberrant cellular proliferation of the endothelium and smooth muscle that results in an angioproliferative vasculopathy with complex involvement of apoptosis and inflammatory pathways. We previously demonstrated Pre-B-Cell Colony Enhancing Factor (PBEF) to be a biomarker and candidate gene in inflammatory lung injury (Ye S et al 2005; Hong et al 2008), with extracellular proinflammatory cytokine-like, NF-kB-mediated activity as well as intracellular enzymatic activity as a phosphoribosyltransferase which regulates intracellular NAD levels (NAMPT activity) and inhibits apoptosis. Thus, we hypothesize that PBEF might be a potential therapeutic target in PAH.

Lack of direct insulin-like action of visfatin/Nampt/PBEF1 in human adipocytes

Visfatin, a protein identified as a secretion product of visceral fat in humans and mice, is also expressed in different anatomical locations, and is known as pre-B cell-colony enhancing factor (PEBF1). It is also an enzyme displaying nicotinamide phosphoribosyltransferase activity (Nampt). The evidence that levels of visfatin correlate with visceral fat mass has been largely debated and widely extended to other regulations in numerous clinical studies and in diverse animal models. On the opposite, the initial findings regarding the capacity of visfatin/Nampt/PEBF1 to bind and to activate the insulin receptor have been scarcely reproduced, and even were contradicted in recent reports. Since the putative insulin mimicking effects of visfatin/Nampt/PEBF1 have never been tested on mature human adipocytes, at least to our knowledge, we tested different human visfatin batches on human fat cells freshly isolated from subcutaneous abdominal fat and exhibiting high insulin responsiveness. Up to 10 nM, visfatin was devoid of clear activatory action on glucose transport in human fat cells while, in the same conditions, insulin increased by more than threefold the basal 2-deoxyglucose uptake. Moreover, visfatin was unable to mimic the lipolysis inhibition induced by insulin. Visfatin definitively cannot be considered as a direct activator of insulin signalling in human fat cells. Nevertheless itsin vivo effects on insulin release and on glucose handling deserve to further study the role of this multifunctional extracellular enzyme in obese and diabetic states.

The visfatin (NAMPT; PBEF1) gene polymorphisms and associations with meat performance traits in three pig breeds kept in the Czech Republic

Visfatin encoded by the <I>NAMPT</I> gene <I>(nicotinamide phosphoribosyltransferase,</I> formerly also known as <I>PBEF – pre-B cell colony-enhancing factor</I>) is suggested to play a role in lipid metabolism and pathophysiology of diabetes mellitus type 2. A new microsatellite <I>SCZ004</I> was detected within intron 9 of the <I>NAMPT</I> gene. In Czech Large White (<I>n</I> = 95) frequencies of alleles <I>282, 286, 287, 299</I>, and <I>304</I> were 0.02, 0.39, 0.07, 0.04, and 0.48, respectively. Allele <I>286</I> was predominant also in Landrace (<I>n</I> = 11) and Black Pied Prestice (<I>n</I> = 11) breeds. Association analysis was carried out between previously reported SNP AM999341:g.669T>C in intron 9 of the <I>NAMPT</I> gene and backfat thickness, average daily gain and lean meat content in Czech Large White (<I>n</I> = 215), Black Pied Prestice (<I>n</I> = 96) and Landrace (<I>n</I> = 105). The <I>CC</I> genotype was associated with higher backfat thickness (<I ≤ 0.01) in Black Pied Prestice, however in Czech Large White <I>CC</I> was associated with lower backfat thickness when compared to <I>TT</I> and <I>CT</I> genotypes (<I ≤ 0.05). In Czech Large White, <I>CC</I> genotype was associated with higher lean meat content when compared to <I>CT</I> (not significant) and <I>TT</I> genotype (<I ≤ 0.05) while in Landrace <I>CC</I> had the lowest lean meat content when compared to <I>CT</I> and <I>TT</I> genotypes but only the difference between <I>CC</I> and <I>CT</I>T was statistically significant (<I ≤ 0.05). In Black Pied Prestice no association with lean meat content was found. Average daily gain was not associated with the SNP in any breed.

Regulation of Inflammatory Cytokine Expression in Pulmonary Epithelial Cells by Pre-B-cell Colony-enhancing Factor via a Nonenzymatic and AP-1-dependent Mechanism

Although our previous studies found Pre-B-cell colony-enhancing factor (PBEF) as a highly up-regulated gene in acute lung injury that could stimulate expressions of other inflammatory cytokines, the underlying molecular mechanisms remain to be fully elucidated. Growing evidence indicates that PBEF is a nicotinamide phosphoribosyltransferase involved in the mammalian salvage pathway of NAD synthesis. This study was designed to determine whether the effect of PBEF to stimulate expressions of inflammatory cytokines depends on its enzymatic activity. We prepared two human PBEF mutant (H247E and H247A) recombinant proteins and overexpressing constructs for their overexpressions in A549 cells and confirmed that enzymatic activities of both mutants were nearly or completely abolished. Two mutants stimulated interleukin-8 (IL-8) expression at both the mRNA level and protein level just as equally effective as the wild-type PBEF did. These effects were due to the increased transcription, not the mRNA stability, of the IL-8 gene. Reporter gene assays and gel shift experiments indicated that AP-1 transcription factor is required to mediate these effects. SB203580, a p38 MAPK pathway inhibitor, and JNK inhibitor 1 can attenuate these effects. Both PBEF mutants similarly stimulated the expression of two other inflammatory cytokines: IL-16 and CCR3. These results indicate that PBEF stimulated expression of IL-8, IL-16, and CCR3 via its non-enzymatic activity. This effect is AP-1-dependent, in part via the p38 MAPK pathway and the JNK pathway. This finding reveals a new insight, which may manifest a novel role of PBEF in the pathogenesis of acute lung injury and other inflammatory disorders.

Dysregulation of Myeloid‐specific Transcription Factors in Congenital Neutropenia

Severe congenital neutropenia (CN) is a heterogeneous hematopoietic syndrome with a typical "maturation arrest" of granulocytic precursors at the promyelocytic stage, inherited in an autosomal dominant or recessive manner. Intriguingly, CN patients have the same bone marrow and blood phenotypes irrespective of inheritance. This suggests that mutations in various genes may lead to the dysregulation of the common myeloid transcription factor(s) in CN. To the extensively studied myeloid-specific transcription factors belong CCAAT/enhancer-binding proteins (C/EBPs) (-alpha, -beta, -epsilon) and PU.1. The relative levels of PU.1 and C/EBPalpha in granulocytic-macrophage progenitors have been suggested to regulate monocyte versus neutrophil cell-fate choice. In CN patients, the myelopoietic maturation program is sharply shifted toward monocytopoiesis, with increased levels of monocytes and no granulocytes in the peripheral blood. We found that in myeloid cells from CN patients C/EBPalpha and its target gene inhibitor of DNA binding 1 (Id1) are abrogated due to a lack of lymphoid enhancer-binding factor 1 (LEF-1) expression but PU.1 is slightly upregulated. Based on these findings, we conclude that in LEF-1-deficient myeloid cells from CN patients misbalanced C/EBPalpha/Id1:PU.1 ratio with a strong shift toward PU.1 could play a decisive role in the improper regulation of myelopoiesis with defective granulocytopoiesis and elevated monocytic differentiation. Recently, we identified nicotinamide phosphoribosyltransferase (NAMPT), also known as pre-B cell colony enhancing factor (PBEF), as an essential enzyme mediating granulocyte colony-stimulating factor (G-CSF)-triggered granulopoiesis in healthy individuals and in individuals with CN. Since CN patients respond to G-CSF treatment even in the absence of LEF-1 and C/EBPalpha, we conclude that treatment of CN patients with pharmacological doses of G-CSF activates NAMPT/NAD(+)/SIRT1-dependent "emergency" granulopoiesis via C/EBPbeta.

Role of pre-B cell colony-enhancing factor in inflammation and acute lung injury

Pre-B-cell colony-enhancing factor (PBEF) is considered originally as cytokine-like molecule secreted by lymphocyte from human peripheral blood.PBEF has been recently identified as a new adipocytokine exerting insulin-mimetic effects by binding to the insulin receptor.PBEF also presents a variety of other biological activations,such as inducing B-cell differentiation,inhibiting neutrophil apoptosis,affecting immune and inflammatory functions,accordingly involving in several diseases such as acute lung injury (ALI),sepsis,atherosclerosis,pre-term labor,diabetes and cancer.It plays as a role of novel biomarker in ALI.Although the molecular mechanisms in the pathogenesis of these diseases are unknown,the discovery of PBEF may provide new idea and tool for studying the mechanisms of some diseases and their diagnosis and treatment. Key words: Pre-B-cell colony-enhancing factor ; Inflammation ; Acute lung injury ;

Pre-B cell colony enhancing factor/NAMPT/visfatin and its role in inflammation-related bone disease

Chronic inflammation affects bone metabolism and is commonly associated with the presence of osteoporosis. Bone loss is directed by various immune mediators such as the pro-inflammatory cytokines tumour necrosis factor-alpha, interleukin 1-beta or interferon-gamma. Pre-B cell colony enhancing factor (PBEF)/nicotinamide phosphoribosyl transferase (NAMPT)/visfatin is a pleiotropic mediator acting as growth factor, cytokine and enzyme involved in energy and nicotinamide adenine dinucleotide (NAD) metabolism. PBEF/NAMPT/visfatin has been recently demonstrated to exert several pro-inflammatory functions. We studied serum levels of PBEF/NAMPT/visfatin in patients with inflammatory bowel diseases (IBD) and their relation with bone mineral density (BMD). Furthermore, we were interested whether PBEF/NAMPT/visfatin affects osteoclastogenesis and involved mediators. PBEF/NAMPT/visfatin serum levels were increased in patients with IBD, correlated positively with disease activity and negatively with BMD, especially in the lumbar spine. Osteoclast precursor cells were generated from peripheral blood mononuclear cells after stimulation with various growth factors such as macrophage colony-stimulating factor (M-CSF) and soluble ligand of receptor activator of nuclear factor kappa B (RANK). In these in vitro studies, PBEF/NAMPT/visfatin suppressed osteoclastogenesis and inhibited the differentiation of osteoclast precursors into tartrate-resistant acid phosphatase positive multinucleated cells. These effects were paralleled by the suppression of the osteoclast typical markers RANK, nuclear factor of activated T-cells c1 (NFATc1) and cathepsin-K. This is the first report demonstrating a potential role for this important cytokine/enzyme in inflammation-related bone disease.

NAMPT is essential for the G-CSF–induced myeloid differentiation via a NAD+–sirtuin-1–dependent pathway

We identified nicotinamide phosphoribosyltransferase (NAMPT), also known as pre-B cell colony enhancing factor (PBEF), as an essential enzyme mediating granulocyte colony-stimulating factor (G-CSF)-triggered granulopoiesis in healthy individuals and in individuals with severe congenital neutropenia. Intracellular NAMPT and NAD(+) amounts in myeloid cells, as well as plasma NAMPT and NAD(+) levels, were increased by G-CSF treatment of both healthy volunteers and individuals with congenital neutropenia. NAMPT administered both extracellularly and intracellularly induced granulocytic differentiation of CD34(+) hematopoietic progenitor cells and of the promyelocytic leukemia cell line HL-60. Treatment of healthy individuals with high doses of vitamin B3 (nicotinamide), a substrate of NAMPT, induced neutrophilic granulocyte differentiation. The molecular events triggered by NAMPT include NAD(+)-dependent sirtuin-1 activation, subsequent induction of CCAAT/enhancer binding protein-alpha and CCAAT/enhancer binding protein-beta, and, ultimately, upregulation of G-CSF synthesis and G-CSF receptor expression. G-CSF, in turn, further increases NAMPT levels. These results reveal a decisive role of the NAD(+) metabolic pathway in G-CSF-triggered myelopoiesis.

Critical role of PBEF expression in pulmonary cell inflammation and permeability

Previous studies in our lab have identified pre-B-cell colony enhancing factor (PBEF) as a novel biomarker in acute lung injury. This study continues to elucidate the underlying molecular mechanism of PBEF in the pathogenesis of acute lung injury in pulmonary cell culture models. Our results revealed that IL-1beta induced PBEF expression in pulmonary vascular endothelial cells at the transcriptional level and a -1535 T-variant in the human PBEF gene promoter significantly attenuated its binding to an IL-1beta-induced unknown transcription factor. This may underlie the reduced expression of PBEF and thus the lower susceptibility to acute lung injury in -1535T carriers. Furthermore, overexpression of PBEF significantly augmented IL-8 secretion and mRNA expression by more than 6-fold and 2-fold in A549 cells and HPAEC, respectively. It also significantly augmented IL-1beta-mediated cell permeability by 44% in A549 cells and 65% in endothelial cells. The knockdown of PBEF expression significantly inhibited IL-1beta-stimulated IL-8 secretion and mRNA level by 60% and 70%, respectively, and the knockdown of PBEF expression also significantly attenuated IL-1beta-induced cell permeability by 29% in epithelial cells and 24% in endothelial cells. PBEF expression also affected the expression of two other inflammatory cytokines (IL-16 and CCR3 genes). These results suggest that PBEF is critically involved in pulmonary vascular and epithelial inflammation and permeability, which are hallmark features in the pathogenesis of acute lung injury. This study lends further support to our finding that PBEF is a potential new target in acute lung injury.

Clinical Utility of Pre-B-Cell Colony-Enhancing Factor in Bronchoalveolar Lavage Fluid of Acute Critical Ill Patients with Lung Infiltrates

Background: Pre-B-cell colony enhancing factor (PBEF) has been suggested as a novel biomarker in sepsis and acute lung injury. We measured the PBEF in bronchoalveolar lavage (BAL) fluid of acute critically ill patients with lung infiltrates in order to evaluate the clinical utility of measuring PBEF in BAL fluid. Methods: BAL fluid was collected by bronchoscope from 185 adult patients with lung infiltrates. An enzyme-linked immunosorbent assay was then performed on the collected fluids to measure the PBEF. Results: Mean patient age was 59.9 14.5 years and 63.8% of patients were males. The mean concentration of PBEF in BAL fluid was 17.5 88.3 ng/mL, and patients with more than 9 ng/mL of PBEF concentration (n=26, 14.1%) had higher Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores on the BAL exam day. However, there were no significant differences in clinical characteristics between survivors and non-survivors. In patients with leukocytosis (n=93) seen on the BAL exam day, the linear regression analysis revealed a significant, positive relationship between PBEF and APACHE II (=0.06), SOFA score (=0.08), Clinical Pulmonary Infection Score (=0.05), and plateau pressure in patients on ventilators (=0.07) (p=0.177, p

Plasma levels of PBEF/Nampt/visfatin are decreased in patients with liver cirrhosis

Liver cirrhosis is a catabolic disease associated with a high incidence of insulin resistance and diabetes mellitus. Pre-B cell colony-enhancing factor/ nicotinamide phosphoribosyltransferase/visfatin has been characterized as a novel adipokine with a potential role in glucose metabolism and nicotinamide dinucleotide (NAD) generation. We studied plasma levels and metabolic relevance of visfatin in 19 patients with cirrhosis and 19 body mass index-, age-, and sex-matched controls. In addition, hepatic mRNA expression was assessed by qPCR in livers of seven patients with cirrhosis and four controls. Circulating visfatin was 78% lower in cirrhotics (P < 0.001) and decreased with worsening of the clinical stage of liver disease. Hepatic visfatin secretion decreased with clinical stage (P < 0.05) and reduced liver function (P = 0.01). Consistent with these data, hepatic visfatin mRNA expression was significantly lower in cirrhotic livers (P < 0.05). Circulating visfatin in cirrhosis was correlated with body cell mass (r = 0.72, P < 0.01) as well as with body fat mass (r = 0.53, P < 0.05) but not with plasma glucose, insulin, the degree of insulin resistance, or whole body glucose oxidation rates. Higher visfatin levels were associated with higher hepatic glucose production (r = 0.53, P < 0.05) and also with a higher arterial ketone body ratio (KBR) (r = 0.48, P < 0.05), an indicator of increased hepatic NAD generation. In conclusion, circulating visfatin levels are significantly decreased in liver cirrhosis, presumably attributable to decreased hepatic expression and production. Plasma visfatin in cirrhosis is not associated with insulin resistance but correlates with hepatic glucose production and the arterial KBR, indicating a potential link between the NAD-generating properties of visfatin and metabolism.

Pre-B cell colony enhancing factor (PBEF)/visfatin induces secretion of MCP-1 in human endothelial cells: Role in visfatin-induced angiogenesis

ObjectivesVisfatin and Monocyte-Chemoattractant-Protein-1 (MCP-1) are elevated in cardiovascular pathologies, insulin-resistant and diabetic states. Visfatin has been reported to exhibit pro-angiogenic actions in human endothelial cells. Given MCP-1's well described pro-angiogenic properties we sought to study the potential interaction between visfatin and MCP-1 in human endothelial cells. We also explored the possible autocrine/paracrine mechanisms governing this potential interaction; specifically we looked at the effect of visfatin on MCP-1's putative receptor (CCR2 receptor) in human endothelial cells. Methods and resultsUsing in vitro angiogenic assays (capillary tube formation and migration), Western blotting and RT-PCR, we found that visfatin, dose-dependently, induced MCP-1 as well as CCR2 levels. We also studied the involvement of PI3Kinase, MAPKinase and NF-κB pathways in visfatin induced MCP-1/CCR2 levels by employing LY294002, U0126 and BAY11-7085, respectively. We found the increase in MCP-1 and CCR2 levels by visfatin were negated by LY294002 and BAY11-7085, but not with U0126, suggesting the crucial role of PI3Kinase and NF-κB pathways in visfatin induced MCP-1 and its autocrine regulation via the CCR2 receptor. Finally, we consolidate the role of MCP-1 in visfatin-induced angiogenesis by employing CCR2 antagonist (RS-102895) and MCP-1 neutralising antibody, respectively. ConclusionsOur novel data reveal that MCP-1 is pivotal in modulating visfatin-induced angiogenesis via NF-κB and PI3Kinase pathways. Furthermore, our findings elucidate the potential influence of autocrine/paracrine mechanisms (via the CCR2 receptor) underlying visfatin's angiogenic effects through MCP-1.