Resistin, an adipokine with potent proinflammatory properties

Resistin is stored in neutrophil granules being released upon challenge with inflammatory stimuli

We have recently shown that resistin is a key mediator of arthritis accumulating in the inflamed joints and exerting its pro-inflammatory properties independently of TNFalpha. Here we evaluate neutrophils as a cellular source of resistin. Human neutrophils were subjected to subcellular fractionation where the presence of resistin was assessed using western blot, ELISA, and mass spectrometry. Presence of resistin on the neutrophil surface was visualized by flow cytometry. More than 95% of the neutrophils in circulation and in synovial fluid express resistin on their surface. Stimulation of mature neutrophils with fMLF induced release of resistin into supernatants and increased expression of resistin on the surface. Resistin is mobilized simultaneously with lactoferrin, a protein found in specific granules, and with granule-stored CR3/CD11b. Subcellular fractionation of human neutrophils demonstrated the presence of resistin in azurophilic and in specific granules. Here we show that neutrophils have two pools of resistin, the major one exists in specific granules, and the second on their cell membrane. Release of resistin from the neutrophil granules probably serves the main source of resistin at the site of inflammation.

Changes in peroxisome proliferator-activated receptor-gamma activity in children with septic shock

PURPOSE

To assess changes in peroxisome proliferator-activated receptor-gamma (PPARgamma) in peripheral blood mononuclear cells (PBMC) from critically ill children with sepsis. Additionally, to investigate the effects of sepsis on the endogenous activator of PPARgamma, 15-deoxy-(12,14)-PGJ(2) (15d-PGJ(2)), and the downstream targets of PPARgamma activity, adiponectin and resistin.

METHODS

Single-center, prospective case-control study in critically ill children with systemic inflammatory response syndrome, sepsis or septic shock.

RESULTS

PPARgamma nuclear protein expression was decreased but PPARgamma activity was increased in PBMC from children with septic shock compared with controls. PPARgamma activity on day 1 was significantly higher in patients with higher pediatric risk of mortality (PRISM) score compared with controls [mean 0.22 optical density (OD) +/- standard error of the mean (SEM) 0.03 versus 0.12 OD +/- 0.02; p < 0.001]. Patients with resolved sepsis had increased levels of the endogenous PPARgamma ligand, 15d-PGJ(2), compared with patients with systemic inflammatory response syndrome (SIRS) and septic shock (77.7 +/- 21.7 versus 58 +/- 16.5 pg/ml; p = 0.03). Plasma high-molecular-weight adiponectin (HMWA) and resistin levels were increased in patients with septic shock on day 1 and were significantly higher in patients with higher PRISM scores. Nonsurvivors from sepsis had higher resistin levels on the first day of hospitalization compared with survivors from septic shock [660 ng/ml, interquartile range (IQR) 585-833 ng/ml versus 143 ng/ml, IQR 66-342 ng/ml; p < 0.05].

CONCLUSIONS

Sepsis is associated with altered PPARgamma expression and activity in PBMC. Plasma adipokines correlate with risk of mortality scores in sepsis and may be useful biomarkers. Further studies are needed to understand the mechanisms underlying changes in PPARgamma in sepsis.

Resistin competes with lipopolysaccharide for binding to toll-like receptor 4

Toll-like receptors (TLRs) are a family of cellular structures activated by recognition of pathogen associated molecular sequences. The activation of TLRs triggers a variety of intracellular mechanisms aiming to protect the host from the invading microorganisms. Lipopolysaccharide (LPS) is the main ligand for TLR4. Here we show that resistin, a cystein-rich protein believed to regulate carbohydrate metabolism, competes with LPS for binding to TLR4. Binding of recombinant resistin to human myeloid and epithelial cells was assessed by flow cytometry and its co-precipitation with TLR4 was demonstrated. Antibodies against TLR4 abolished resistin binding to human leucocytes and cytokine production by peripheral blood mononuclear cells in response to resistin stimulation. In contrast, isotype-matched murine IgG or TLR2 antibodies were unable to prevent binding of resistin to the cells. Similarly, TLR4-dependent pattern of resistin binding was observed in epithelial cell line HEK293 (human epithelial kidney cell), where TLR4 transfected, but not myeloid differentiation factor 2/CD14-transfected, TLR2 transfected or HEKnull cells, responded functionally to resistin stimulation. Intracellular signalling of resistin was assessed using inhibitors of transcription factors mitogen activated protein kinases, nuclear factor-kappaB, phosphoinositide 3-kinase and siRNA targeting TLR4 and human myeloid differentiation factor 88. Results demonstrate that TLR4 serves as a receptor for the pro-inflammatory effects of resistin in human cells. This may partly explain the multifunctional role of resistin in chronic inflammation, atherosclerosis and insulin resistance.

The role of resistin as a regulator of inflammation: Implications for various human pathologies

Resistin was originally described as an adipocyte-secreted peptide that induced insulin resistance in rodents. Increasing evidence indicates its important regulatory roles in various biological processes, including several inflammatory diseases. Further studies have shown that resistin in humans, in contrast to its production by adipocytes in mice, is synthesized predominantly by mononuclear cells both within and outside adipose tissue. Possible roles for resistin in obesity-related subclinical inflammation, atherosclerosis and cardiovascular disease, non-alcoholic fatty liver disease, rheumatic diseases, malignant tumors, asthma, inflammatory bowel disease, and chronic kidney disease have already been demonstrated. In addition, resistin can modulate several molecular pathways involved in metabolic, inflammatory, and autoimmune diseases. In this review, current knowledge about the functions and pathophysiological implications of resistin in different human pathologies is summarized, although there is a significant lack of firm evidence regarding the specific role resistin plays in the "orchestra" of the numerous mediators of inflammation.

Influence of prematurity and growth restriction on the adipokine profile, IGF1, and ghrelin levels in cord blood: relationship with glucose metabolism

OBJECTIVE

To determine the influence of gestational age and fetal growth restriction on the cord blood adipokine profile, IGF1, and ghrelin levels, and their relationship with glucose metabolism.

STUDY DESIGN

One hundred and ninety newborns (99 preterm and 91 full term) were studied and, according to their anthropometry at birth, classified as small (SGA) or adequate for gestational age (AGA).

METHODS

Venous cord blood serum levels of IGF1, IGF binding protein 3 (IGFBP-3), adiponectin, resistin, leptin, soluble leptin receptor (sOB-R), tumoral necrosis factor-alpha, interleukin 6 (IL-6), total ghrelin, and acylated ghrelin were determined and compared between preterm and full-term, as well as between SGA and AGA, newborns. Correlations with newborn weight, gestational age, and homeostatic model assessment (HOMA) index, as an index of insulin resistance, were determined.

RESULTS

Preterm newborns had higher HOMA, sOB-R, resistin, and IL-6 and lower IGF1, IGFBP-3, leptin, and adiponectin levels than full-term newborns. SGA had lower IGF1, IGFBP-3, leptin, IL-6, and adiponectin and higher sOB-R and total ghrelin than AGA newborns. Adiponectin and HOMA showed independent positive and negative correlations with gestational age respectively, but not with neonatal weight. Birth weight was correlated positively with IGF1 and leptin levels and negatively with total ghrelin ones.

CONCLUSIONS

Our findings suggest that the lack of proper acquisition of adipose tissue by the fetus either due to prematurity or to fetal growth restriction is associated with changes in the cord blood adipokine profile that may contribute to the impairment of glucose metabolism.

Adipose tissue: the new endocrine organ? A review article

Fat is either white or brown, the latter being found principally in neonates. White fat, which comprises adipocytes, pre-adipocytes, macrophages, endothelial cells, fibroblasts, and leukocytes, actively participates in hormonal and inflammatory systems. Adipokines include hormones such as leptin, adiponectin, visfatin, apelin, vaspin, hepcidine, chemerin, omentin, and inflammatory cytokines, including tumor necrosis factor alpha (TNF), monocyte chemoattractant protein-1 (MCP-1), and plasminogen activator protein (PAI). Multiple roles in metabolic and inflammatory responses have been assigned to adipokines; this review describes the molecular actions and clinical significance of the more important adipokines. The array of adipokines evidences diverse roles for adipose tissue, which looms large in the mediators of inflammation and metabolism. For this reason, treating obesity is more than a reduction of excess fat; it is also the treatment of obesity's comorbidities, many of which will some day be treated by drugs that counteract derangements induced by adipokine excesses.

Adenosine infusion attenuates soluble RAGE in endotoxin-induced inflammation in human volunteers

AIM

To evaluate possible anti-inflammatory effects of pre-treatment with adenosine in a human experimental inflammatory model.

METHODS

The study design was double-blind, crossover, placebo-controlled and randomized. In the Intensive Care Unit of a university hospital, 16 healthy male volunteers were treated for 5.5 h with infusions of adenosine 40 microg kg(-1) min(-1) or placebo. Thirty minutes after the start of adenosine or placebo, 2 ng kg(-1)E-Coli endotoxin was administered. Heart rate, body temperature, blood pressure, plasma cytokines (TNF-alpha, IL-6 and IL-10), soluble RAGE and resistin, exhaled nitric oxide and nitrite/nitrate in urine were determined.

RESULTS

Endotoxin elicited the expected clinical signs of an inflammatory reaction (tachycardia, fever) and led to prominent release of the cytokines studied (P < 0.001). Resistin in plasma increased after endotoxin (P < 0.001). After placebo treatment, soluble RAGE (sRAGE) in plasma increased 5 h after the endotoxin challenge (P < 0.001) but not after adenosine. After placebo, orally exhaled NO increased with a peak at 4 h (P < 0.001), although there was no statistically significant difference between the two treatments. Nitrite/nitrate in urine (n = 11) did not differ between adenosine and placebo treatments.

CONCLUSION

In conclusion, adenosine infusion starting before endotoxin challenge in humans attenuated sRAGE significantly but otherwise had no clear anti-inflammatory effect. Adenosine as a potential anti-inflammatory treatment in humans needs further study, including use of higher doses. The mechanism underlying the effect of adenosines on sRAGE remains unknown.

Neutrophil-derived hyperresistinemia in severe acute streptococcal infections

The concept of neutrophil activation and degranulation as important contributors to disease pathology in invasive group A streptococcal infections has recently been emphasized. This study focuses on two of the most severe streptococcal manifestations, toxic shock syndrome and necrotizing fasciitis, and the newly described proinflammatory molecule resistin, known to derive from adipocytes and monocytes. We demonstrate for the first time that these conditions are characterized by hyperresistinemia in circulation as well as at the local site of infection. Importantly, analyses of patient tissue biopsies and whole blood revealed that neutrophils represent a novel and dominant source of resistin in bacterial septic shock. This was confirmed by the identification of resistin within neutrophil azurophilic granules. In vitro assays using primary neutrophils showed that resistin release was readily triggered by streptococcal cell wall components and by the streptococcal M1 protein, but not by the potent streptococcal superantigens. This is the first report demonstrating that resistin is released from neutrophils in response to microbial stimuli, which adds resistin to the neutrophil granule proteins that are likely to contribute to the pathologic inflammatory responses associated with severe streptococcal infections.

Maternal plasma visfatin in preterm labor

OBJECTIVE

Visfatin, a novel adipokine with diabetogenic and immunoregulatory properties, has been implicated in the pathophysiology of insulin resistance, as well as in various acute and chronic inflammatory disorders. We have previously reported that amniotic fluid concentrations of visfatin are higher in patients with preterm labor (PTL) and intra-amniotic infection than in patients with PTL without infection. The aim of this study was to determine whether spontaneous PTL with intact membranes and intra-amniotic infection/inflammation (IAI) is associated with changes in maternal plasma circulating visfatin concentrations.

STUDY DESIGN

This cross-sectional study included patients in the following groups: (1) normal pregnant women (n = 123); (2) patients with an episode of PTL and intact membranes without IAI who delivered at term (n = 57); (3) PTL without IAI who delivered preterm (n = 47); and (4) PTL with IAI who delivered preterm (n = 57). Plasma visfatin concentrations were determined by ELISA. Non-parametric statistics were used for analysis.

RESULTS

(1) PTL with IAI leading to preterm delivery was associated with a higher median maternal plasma concentration of visfatin than normal pregnancy; (2) among patients with PTL, those with IAI had the highest median maternal concentration of visfatin; (3) the changes in maternal plasma visfatin remained significant after adjusting for maternal age, body mass index, gestational age at sampling, and birth weight.

CONCLUSION

(1) PTL with IAI is characterized by high maternal circulating visfatin concentrations; (2) these findings suggest that visfatin plays a role in the regulation of the metabolic adaptations to insults resulting in PTL in the context of IAI.

The effects of PACAP and related peptides on leptin, soluble leptin receptor and resistin in normal condition and LPS-induced inflammation

Leptin and resistin are adipokines considered as pro-inflammatory factors related to metabolic syndrome, inflammatory and/or autoimmune conditions. Pituitary adenylate cyclase activating peptide (PACAP) is a pleiotropic neuropeptide with anti-inflammatory properties. We investigated the influence of PACAP on the serum level of leptin, soluble leptin receptor (SLR) and resistin in ordinary and LPS-induced inflammatory conditions using PACAP38 and a series of selective agonist for each PACAP receptor types. It was found that PACAP exerted opposite effects on the leptin:SLR ratio and the serum resistin level. In ordinary condition, PACAP acted as a pro-inflammatory factor by increasing the leptin:SLR ratio and serum resistin level. But in LPS-induced acute inflammatory condition, PACAP not only antagonized the effects of LPS, but also even reversed the effects of LPS. In mice treated with LPS, co-treatment with PACAP decreased the serum leptin and resistin levels and increased the serum soluble leptin receptor level significantly. It was also found that, in ordinary condition, treatment with PAC1 agonist maxadilan induced marked increase in serum leptin, leptin:SLR ratios and resistin levels; while in LPS-induced inflammation, VPAC1 mediated much more anti-inflammatory and reversing-LPS effects of PACAP on leptin and resistin than PAC1 and VPAC2. It is concluded that different receptors mediates different effects of PACAP on leptin, SLR and resistin in non-inflammatory and LPS-induced inflammatory conditions.

Type 1 autoimmune hepatitis and adipokines: new markers for activity and disease progression?

PURPOSE

Cytokines may play an important role as inflammatory factors in liver diseases. There is some evidence suggesting a link between adiponectin-biliary function and liver disease. The aim of this study was to clarify the behavior of adipokines in autoimmune hepatitis type 1.

METHODS

We assessed the circulating levels of adiponectin, tumor necrosis factor-alpha, resistin and leptin in 42 patients with autoimmune hepatitis, comparing them with 42 healthy subjects who were matched for age and sex and with 31 patients with nonalcoholic steatohepatitis (NASH), evaluating the associations with markers of cytolysis, cholestasis, and histological severity.

RESULTS

Adiponectin and TNF-alpha values were higher in patients compared to controls. The patients showed significantly higher Homeostasis Model Assessment values, suggesting an increased insulin resistance and serum levels of adiponectin positively correlated with gamma-glutamyltranspeptidase and alkaline phosphatase values after a simple regression analysis. Serum levels of resistin positively correlated with elevated aminotransferases and bilirubin values, and serum levels of TNF-alpha positively correlated with elevated alanine-aminotransferase and resistin values. The concentration of adiponectin increased significantly with staging of the disease. Patients with NASH showed lower levels of adiponectin and higher levels of resistin than AIH patients and controls.

CONCLUSIONS

Patients with AIH showed significantly higher adiponectin concentrations than controls despite their higher HOMA-IR values. The significant correlation between adiponectin levels and serological features of cholestasis suggested an association with biliary function. Our results indicate that adiponectin may be a possible marker for disease progression in AIH.

Serum Levels of Resistin in Allergic Rhinitis and its Relationship with Disease Severity

Background

Resistin, a recently discovered adipokine, has been shown to have proinflammatory properties in humans. The purpose of this study was to evaluate serum resistin levels in children with allergic rhinitis (AR) and to investigate its association with clinical disease severity, parameters of atopy and pro-/anti-inflammatory cytokines.

Methods

A case-controlled study was performed on 50 pediatric patients with persistent AR and 30 healthy controls with similar age, sex, and body mass index. Serum levels of resistin, parameters of atopy, and cytokines were analyzed. The nasal symptom scores were evaluated and patients were classified into mild (n = 20) and moderate-severe (n = 30) persistent AR.

Results

Serum levels of resistin were significantly increased in children with AR compared with controls (p < 0.001). Serum levels of resistin went hand in hand with disease severity as they were significantly higher in moderate-severe than mild persistent AR. In addition, they correlated positively with nasal symptom scores (r = 0.74; p < 0.001). A significant positive correlation was observed between serum levels of resistin and IL-6 (r = 0.358; p = 0.011).

Conclusion

Patients with persistent AR were found to have higher serum levels of resistin, and resistin levels increased with the progress of disease severity. Resistin may represent a novel link between inflammation and AR.

Adipocytokines are associated with radiographic joint damage in rheumatoid arthritis

OBJECTIVE

Obesity protects against radiographic joint damage in rheumatoid arthritis (RA) through poorly defined mechanisms. Adipocytokines are produced in adipose tissue and modulate inflammatory responses and radiographic joint damage in animal models. The purpose of this study was to examine the hypothesis that adipocytokines modulate inflammation and radiographic joint damage in patients with RA.

METHODS

We compared serum concentrations of leptin, resistin, adiponectin, and visfatin in 167 RA patients and 91 control subjects. The independent association between adipocytokines and body mass index (BMI), measures of inflammation (C-reactive protein [CRP], interleukin-6 [IL-6], and tumor necrosis factor alpha [TNFalpha]), and radiographic joint damage (Larsen score; n = 93 patients) was examined in RA patients by multivariable regression analysis first controlling for age, race, and sex, and then for obesity (BMI) and inflammation (TNFalpha, IL-6, and CRP).

RESULTS

Concentrations of all adipocytokines were significantly higher in RA patients than in controls; for visfatin and adiponectin, this association remained significant after adjusting for BMI, inflammation, or both. Visfatin concentrations were associated with higher Larsen scores, and this association remained significant after adjustment for age, race, sex, disease duration, BMI, and inflammation (odds ratio [OR] 2.38 [95% confidence interval (95% CI) 1.32-4.29], P = 0.004). Leptin concentrations showed a positive association with the BMI (rho = 0.58, P < 0.01) and showed a negative association with the Larsen score after adjustment for inflammation (OR 0.32 [95% CI 0.17-0.61], P < 0.001), but not after adjustment for BMI (OR 0.86 [95% CI 0.42-1.73], P = 0.67).

CONCLUSION

Concentrations of adipocytokines are increased in patients with RA and may modulate radiographic joint damage. Visfatin is associated with increased, and leptin with reduced, levels of radiographic joint damage.

Adipokines in nonalcoholic steatohepatitis: from pathogenesis to implications in diagnosis and therapy

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome and can vary from benign steatosis to end-stage liver disease. The pathogenesis of non-alcoholic steatohepatitis (NASH) is currently thought to involve a multiple-hit process with the first hit being the accumulation of liver fat which is followed by the development of necroinflammation and fibrosis. There is mounting evidence that cytokines secreted from adipose tissue, namely, adipokines, are implicated in the pathogenesis and progression of NAFLD. In the current review, we explore the role of these adipokines, particularly leptin, adiponectin, resistin, tumor necrosis factor-a, and interleukin-6 in NASH, as elucidated in experimental models and clinical practice. We also comment on their potential use as noninvasive markers for differentiating simple fatty liver from NASH as well as on their potential future therapeutic role in patients with NASH.

Mechanism of inhibitory effect of atorvastatin on resistin expression induced by tumor necrosis factor-alpha in macrophages

Atorvastatin has been shown to reduce resistin expression in macrophages after pro-inflammatory stimulation. However, the mechanism of reducing resistin expression by atorvastatin is not known. Therefore, we sought to investigate the molecular mechanisms of atorvastatin for reducing resistin expression after proinflammatory cytokine, tumor necrosis factor-α (TNF-α) stimulation in cultured macrophages. Cultured macrophages were obtained from human peripheral blood mononuclear cells. TNF-α stimulation increased resistin protein and mRNA expression and atorvastatin inhibited the induction of resistin by TNF-α. Addition of mevalonate induced resistin protein expression similar to TNF-α stimulation. However, atorvastatin did not have effect on resistin protein expression induced by mevalonate. SP600125 and JNK small interfering RNA (siRNA) completely attenuated the resistin protein expression induced by TNF-α and mevalonate. TNF-α induced phosphorylation of Rac, while atorvastatin and Rac-1 inhibitor inhibited the phosphorylation of Rac induced by TNF-α. The gel shift and promoter activity assay showed that TNF-α increased AP-1-binding activity and resistin promoter activity, while SP600125 and atorvastatin inhibited the AP-1-binding activity and resistin promoter activity induced by TNF-α. Recombinant resistin and TNF-α significantly reduced glucose uptake in cultured macrophages, while atorvastatin reversed the reduced glucose uptake by TNF-α. In conclusion, JNK and Rac pathway mediates the inhibitory effect of atorvastatin on resistin expression induced by TNF-α.

The expression of human resistin in different leucocyte lineages is modulated by LPS and TNFalpha

OBJECTIVE

Human resistin has been linked to several inflammatory diseases such as atherosclerosis. This study aimed to clarify the expression of resistin in different inflammatory cells and its effect on endothelial cells.

RESULTS

In this study, RNA and protein expression of resistin were detected in human primary neutrophils, monocytes, and T cells as well as in human Jurkat T cells, RPMI-8226 B cells, monocytic U937, and myeloblastic HL-60 cell lines. The highest resistin protein and mRNA level were detected in neutrophils, primary monocytes, and monocytic U937 cells. The RNA expression of resistin was upregulated both in neutrophils and in U937 cells after exposure to LPS. Also TNFalpha induced resistin RNA expression in neutrophils, U937, T-lymphocytic Jurkat cells, and B-lymphocytic RPMI-8226 cells. The RNA and protein expression of resistin decreased as the monocytic U937 cells differentiated into macrophage-like cells. In endothelial EA.hy 926 cells, resistin increased the expression of MCP-1 and PECAM-1 and adhesion of monocytes to endothelial cells.

CONCLUSIONS

The wide-ranging expression of resistin in white blood cells and the upregulation of its expression by inflammatory reagents LPS and TNFalpha support the fact that increased resistin could be involved in several inflammatory diseases.

Hepatic lipid metabolism and non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is an increasingly recognized pathology with a high prevalence and a possible evolution to its inflammatory counterpart (non-alcoholic steatohepatitis, or NASH). The pathophysiology of NAFLD and NASH has many links with the metabolic syndrome, sharing a causative factor in insulin resistance. According to a two-hit hypothesis, increased intrahepatic triglyceride accumulation (due to increased synthesis, decreased export, or both) is followed by a second step (or "hit"), which may lead to NASH. The latter likely involves oxidative stress, cytochrome P450 activation, lipid peroxidation, increased inflammatory cytokine production, activation of hepatic stellate cells and apoptosis. However, both "hits" may be caused by the same factors. The aim of this article is to overview the biochemical steps of fat regulation in the liver and the alterations occurring in the pathogenesis of NAFLD and NASH.

Resistin is elevated following traumatic joint injury and causes matrix degradation and release of inflammatory cytokines from articular cartilage in vitro

OBJECTIVE

Resistin is a secreted factor that is elevated in rheumatoid arthritis (RA) and believed to drive joint inflammation in vivo. This study was undertaken to determine if resistin is present in the joint following joint injury and to elucidate the role of resistin in cartilage degradation.

METHODS

The level of resistin was measured in paired synovial fluid (SF) and serum samples from patients following joint injury (anterior cruciate ligament, ACL or meniscus tear). Localization of resistin was visualized by immunohistochemistry of synovial tissue and cartilage from healthy and OA donors. Mouse and human cartilage cultures were used to assess the effect of resistin on cartilage metabolism.

RESULTS

In trauma patients, resistin levels declined with increasing time post injury. The resistin levels were highest in samples collected up to 1 week following traumatic injury (SF: 2980 pg/ml, serum: 7901 pg/ml) and lowest in samples collected 6-26 years post injury (SF: 686 pg/ml, serum: 5682 pg/ml). Resistin was shown to be expressed in macrophage-like cells in both healthy and OA synovial tissue. Treatment of mouse cartilage cultures with recombinant resistin led to a dose dependent loss of proteoglycan and induction of inflammatory cytokine and PGE(2) production. Recombinant resistin inhibited proteoglycan synthesis in human cartilage explants.

CONCLUSION

Resistin is elevated both systemically and locally in the weeks immediately following joint injury and has a direct effect on cartilage matrix turnover and cytokine production. Resistin may play a role in the early stages of trauma-induced OA and may represent a new therapeutic target to slow joint destruction in OA.

Association of -394C>G and -420C>G polymorphisms in the RETN gene with T2DM and CHD and a new potential SNP might be exist in exon 3 of RETN gene in Chinese

Genetic variations of the human RETN gene are associated with metabolic phenotypes, including obesity, insulin sensitivity, diabetes, and coronary heart disease (CHD). There are few studies of two gene variants, -394C>G and -420C>G, in Chinese population. This study investigated the distribution of RETN gene, single nucleotide polymorphisms (SNPs), in Chinese Han population and the association of the polymorphisms with type 2 diabetes mellitus (T2DM) and CHD. In a population-based, case-control genetic association study, a total of 961 subjects were recruited from the community, including 318 T2DM patients, 273 CHD patients, and 370 unrelated healthy control individuals. Serum lipid levels were detected. Two SNPs of RETN gene, -394C>G and -420C>G, were genotyped by PCR-RFLP. Unknown Polymorphisms were screened with the technique of denaturing high performance liquid chromatography (DHPLC). The frequencies of RETN -394G allele in T2DM group, CHD group, and control group were 0.3066, 0.3555, and 0.3481, respectively, which are met with the Hardy-Weinberg equilibrium. There is a significant difference of the comparison of sex in T2DM group of RETN gene SNP-394C>G (P < 0.05). Compared with controls, there was no significant difference in the distribution of genotypes and allele frequencies of -394C>G polymorphic site in T2DM patients and CHD patients, respectively. No direct association was found between the -394C>G polymorphism and T2DM or CHD. The frequencies of RETN -420G allele in T2DM group, CHD group, and control group were 0.4009, 0.3725, and 0.3859, respectively, which are met with the Hardy-Weinberg equilibrium. The frequencies of RETN -420G allele in T2DM groups and control groups of Chinese population are significantly different from those in European population (0.40 vs. 0.27, 0.39 vs. 0.26) (P < 0.01). Compared with controls, there was no significant difference in distribution of genotypes and allele frequencies of -420C>G polymorphic site in T2DM patients and CHD patients, respectively. No direct association was found between the -420C>G polymorphism and T2DM or CHD. In addition, we found new potential SNP +593G>C in exon 3 of RETN gene using DHPLC. The RETN gene exhibits sex and ethnic differences. +593G>C of RETN gene might be a new potential SNP in exon 3 of RETN gene. Association between SNP -394C>G and -420C>G of RETN gene with T2DM and CHD in Chinese needs more exploration.

Alternatively activated macrophage-derived RELM-{alpha} is a negative regulator of type 2 inflammation in the lung

Differentiation and recruitment of alternatively activated macrophages (AAMacs) are hallmarks of several inflammatory conditions associated with infection, allergy, diabetes, and cancer. AAMacs are defined by the expression of Arginase 1, chitinase-like molecules, and resistin-like molecule (RELM) alpha/FIZZ1; however, the influence of these molecules on the development, progression, or resolution of inflammatory diseases is unknown. We describe the generation of RELM-alpha-deficient (Retnla(-/-)) mice and use a model of T helper type 2 (Th2) cytokine-dependent lung inflammation to identify an immunoregulatory role for RELM-alpha. After challenge with Schistosoma mansoni (Sm) eggs, Retnla(-/-) mice developed exacerbated lung inflammation compared with their wild-type counterparts, characterized by excessive pulmonary vascularization, increased size of egg-induced granulomas, and elevated fibrosis. Associated with increased disease severity, Sm egg-challenged Retnla(-/-) mice exhibited elevated expression of pathogen-specific CD4(+) T cell-derived Th2 cytokines. Consistent with immunoregulatory properties, recombinant RELM-alpha could bind to macrophages and effector CD4(+) Th2 cells and inhibited Th2 cytokine production in a Bruton's tyrosine kinase-dependent manner. Additionally, Retnla(-/-) AAMacs promoted exaggerated antigen-specific Th2 cell differentiation. Collectively, these data identify a previously unrecognized role for AAMac-derived RELM-alpha in limiting the pathogenesis of Th2 cytokine-mediated pulmonary inflammation, in part through the regulation of CD4(+) T cell responses.

High resistin and interleukin-6 levels are associated with gestational diabetes mellitus

Resistin is a cysteine-rich adipokine originally described as a molecular link between obesity and insulin resistance in rodents. In this study, we hypothesised that serum resistin concentrations are elevated in patients with gestational diabetes mellitus (GDM) when compared with pregnant women with normal glucose tolerance (NGT) and related to proinflammatory interleukin-6 (IL-6) and other factors conferring insulin resistance. Serum resistin and IL-6 were measured by enzyme-linked immunosorbent assay (ELISA) in 81 women with GDM, 82 women with NGT between 24 and 31 weeks of gestation and 25 healthy non-pregnant women. Resistin concentrations were significantly higher in the GDM (21.9 [17.55-25.40] ng/ml) than in the NGT group (19.03 [15.92-23.91] ng/ml, p = 0.047), as well as in the non-pregnant women (14.8 [13.7-16.6] ng/ml, p < 0.0001). Serum IL-6 levels were elevated in the GDM (1.0 [0.7-1.5] pg/ml) as compared with the NGT group (0.8 [0.5-1.1] pg/ml, p = 0.006) and the non-pregnant controls (0.7 [0.5-1.1] pg/ml, p = 0.04). Multiple regression analysis revealed that in the pregnant women circulating resistin was related to serum IL-6 (beta = 0.33, p = 0.0004) but not to insulin or the index of insulin resistance. It is concluded that the finding of high resistin and IL-6 levels in women with gestational diabetes might confirm a role of low-grade inflammation in the pathogenesis of GDM.

[Adipocytokines: emerging mediators of the immune response and inflammation]

Scientific interest in the biology of white adipose tissue (WAT) has increased since the discovery of leptin in 1994. The description of the effects of leptin, the product of the ob gene, has started to clarify the role of adipose tissue in the physiopathology of obesity related diseases and has helped in the identification of a great number of other molecules (named adipocytokines), some of them with a proinflammatory nature. In rheumatic diseases, adipocytokines derived from the WAT are among the most important factors related to obesity and promote inflammatory and/or autoimmune conditions. In this review we will present the most recent advances in adipocytokine research, with special attention to the role of leptin, adiponectin, resistin and visfatin and inflammatory, autoimmune and rheumatic diseases.

Understanding Haemophilus parasuis infection in porcine spleen through a transcriptomics approach

Background

Haemophilus parasuis (HPS) is an important swine pathogen that causes Glässer's disease, which is characterized by fibrinous polyserositis, meningitis and arthritis. The molecular mechanisms that underlie the pathogenesis of the disease remain poorly understood, particularly the resistance of porcine immune system to HPS invasion. In this study, we investigated the global changes in gene expression in the spleen following HPS infection using the Affymetrix Porcine Genechip™.

Results

A total of 931 differentially expressed (DE) transcripts were identified in the porcine spleen 7 days after HPS infection; of these, 92 unique genes showed differential expression patterns based on analysis using BLASTX and Gene Ontology. The DE genes involved in the immune response included genes for inflammasomes (RETN, S100A8, S100A9, S100A12), adhesion molecules (CLDN3, CSPG2, CD44, LGALS8), transcription factors (ZBTB16, SLC39A14, CEBPD, CEBPB), acute-phase proteins and complement (SAA1, LTF, HP, C3), differentiation genes for epithelial cells and keratinocytes (TGM1, MS4A8B, CSTA), and genes related to antigen processing and presentation (HLA-B, HLA-DRB1). Further immunostimulation analyses indicated that mRNA levels of S100A8, S100A9, and S100A12 in porcine PK-15 cells increased within 48 h and were sustained after administration of lipopolysaccharide (LPS) and Poly(I:C) respectively. In addition, mapping of DE genes to porcine health traits QTL regions showed that 70 genes were distributed in 7 different known porcine QTL regions. Finally, 10 DE genes were validated by quantitative PCR.

Conclusion

Our findings demonstrate previously unrecognized changes in gene transcription that are associated with HPS infection in vivo, and many potential cascades identified in the study clearly merit further investigation. Our data provide new clues to the nature of the immune response in mammals, and we have identified candidate genes that are related to resistance to HPS.

Circulating levels of resistin and risk of type 2 diabetes in men and women: results from two prospective cohorts

OBJECTIVE

The purpose of this study was to investigate the role of circulating resistin levels in the development of type 2 diabetes using two prospective cohorts of well-characterized men and women.

RESEARCH DESIGN AND METHODS

We conducted two prospective case-control studies nested in the Women's Health Study (WHS) and Physicians' Health Study II (PHS II). In the WHS, during a median of 10-years of follow-up, 359 postmenopausal women, who were apparently healthy at baseline and later developed type 2 diabetes, were prospectively matched with 359 healthy control subjects. In the PHS II, with 8 years of total follow-up, 170 men, who were apparently healthy at baseline and later developed type 2 diabetes, were matched with 170 healthy control subjects. Control subjects were matched by age, race, and time of blood draw.

RESULTS

Resistin levels at baseline were significantly higher in women than in men (P = 0.003) and in case patients than in control subjects for both women (P < 0.001) and men (P = 0.07). After adjustment for matching factors, physical activity, alcohol intake, smoking, and family history of diabetes, the relative risk of type 2 diabetes comparing the highest to the lowest quartile of resistin in women was 2.22 ([95% CI 1.32-3.73]; Ptrend = 0.002). This association was attenuated after further adjustment for BMI (1.51 [0.86-2.65]; Ptrend = 0.20) or C-reactive protein (1.18 [0.68-2.07]; Ptrend = 0.60). A similar but weaker pattern was observed in men.

CONCLUSIONS

Elevated levels of circulating resistin were significantly related to increased risk of type 2 diabetes, which appears to be partially accounted for by adiposity and the inflammatory process.

Resistin increases islet blood flow and decreases subcutaneous adipose tissue blood flow in anaesthetized rats

AIM

Resistin is an adipokine which has been suggested to participate in the induction of insulin resistance associated with type 2 diabetes. The aim of the present study was to investigate whether acute administration of resistin influences tissue blood perfusion in rats.

METHODS

Resistin was administered as an intravenous infusion of 7.5 microg h(-1) (1.5 mL h(-1)) for 30 min to rats anaesthetized with thiobutabarbital. A microsphere technique was used to estimate the blood flow to six different depots of white adipose tissue (WAT), brown adipose tissue (BAT), as well as to the pancreas, islets, duodenum, colon, kidneys, adrenal glands and liver.

RESULTS

Resistin administration led to an increased blood flow to the pancreas and islets and a decrease in subcutaneous WAT and BAT. Intra-abdominal white adipose tissue blood flow and that to other organs were not affected.

CONCLUSION

Acute administration of resistin markedly affects the blood perfusion of both the pancreas and subcutaneous white adipose tissue depots. At present it is unknown whether resistin exerts a direct effect on the vasculature, or works through local or systemic activation of endothelial cells and/or macrophages. The extent to which this might contribute to the insulin resistance caused by resistin is yet unknown.

Neuroendocrine factors in the regulation of inflammation: excessive adiposity and calorie restriction

Acute inflammation is usually a self-limited life preserving response, triggered by pathogens and/or traumatic injuries. This transient response normally leads to removal of harmful agents and to healing of the damaged tissues. In contrast, unchecked or chronic inflammation can lead to persistent tissue and organ damage by activated leukocytes, cytokines, or collagen deposition. Excessive energy intake and adiposity cause systemic inflammation, whereas calorie restriction without malnutrition exerts a potent anti-inflammatory effect. As individuals accumulate fat and their adipocytes enlarge, adipose tissue undergoes molecular and cellular alterations, macrophages accumulate, and inflammation ensues. Overweight/obese subjects have significantly higher plasma concentrations of C-reactive protein and several cytokines, including IL-6, IL-8, IL-18, and TNF-alpha. Experimental animals on a chronic CR regimen, instead, have low levels of circulating inflammatory cytokines, low blood lymphocyte levels, reduced production of inflammatory cytokines by the white blood cells in response to stimulation, and cortisol levels in the high normal range. Recent data demonstrate that CR exerts a powerful anti-inflammatory effect also in non-human primates and humans. Multiple metabolic and neuroendocrine mechanisms are responsible for the CR-mediated anti-inflammatory effects, including reduced adiposity and secretion of pro-inflammatory adipokines, enhanced glucocorticoid production, reduced plasma glucose and advanced glycation end-product concentrations, increased parasympathetic tone, and increased ghrelin production. Measuring tissue specific effects of CR using genomic, proteomic, and metabolomic techniques in humans will foster the understanding of the complex biological processes involved in the anti-inflammatory and anti-aging effects of CR.

Increased serum resistin concentration in patients with chronic pancreatitis: possible cause of pancreatic fibrosis

BACKGROUND

Resistin is an adipokine, which displays proinflammatory properties. Thus, it is likely that resistin can influence the course of chronic pancreatitis, and/or that chronic pancreatitis may affect the serum resistin concentration.

GOALS

The aim of the present study was to determine the serum resistin concentration in patients with chronic pancreatitis and to analyze the relationship between serum resistin concentration and serum concentrations of leptin (proinflammatory adipokine) and adiponectin (anti-inflammatory adipokine).

STUDY

A total of 23 male, nondiabetic patients with chronic pancreatitis of alcoholic origin and 16 healthy subjects were examined. Fasting blood samples were collected from patients in both groups. Serum resistin concentration was assayed by enzyme-linked immunosorbent assay. Serum adiponectin, leptin, and insulin concentrations were determined by radioimmunoassay.

RESULTS

Serum resistin concentration was significantly higher in patients with chronic pancreatitis as compared with control subjects. In contrast, patients with chronic pancreatitis had lower serum leptin and insulin concentrations than healthy subjects. There were no statistically significant differences in serum adiponectin concentration between patients with pancreatitis and healthy subjects.

CONCLUSIONS

The results presented in this paper indicate that chronic pancreatitis in human is associated with the increase in serum resistin concentration and with the decrease in serum leptin and insulin concentrations. It can be supposed that resistin, by stimulation of tumor necrosis factor-alpha synthesis in blood mononuclear cells and in macrophages, increases the concentration of tumor necrosis factor-alpha, which in turn activates stellate cells. Activated stellate cells can produce collagen, eventually resulting in the development of pancreatic fibrosis.

Common inflammatory mediators orchestrate pathophysiological processes in rheumatoid arthritis and atherosclerosis

RA is characterized by a systemic inflammatory state, in which immune cells and soluble mediators play a crucial role. These inflammatory processes resemble those in other chronic inflammatory diseases, such as atherosclerosis. The chronic systemic inflammation in RA can be considered as an independent risk factor for the development of atherosclerosis, and represents an important field to investigate the reasons of the increase of acute cardiovascular events in RA. In the present review, we focused on several mediators of autoimmunity, inflammation and endothelial dysfunction, which can be considered the most promising targets to prevent atherogenesis in RA. Among several mediators, the pro-inflammatory cytokine TNF-alpha has been shown as a crucial factor to induce atherosclerosis in RA patients.

Peripheral mononuclear cell resistin mRNA expression is increased in type 2 diabetic women

Resistin has been shown to cause insulin resistance and to impair glucose tolerance in rodents, but in humans its physiological role still remains elusive. The aim of this study was to examine whether resistin mRNA expression in human peripheral mononuclear cells (PBMCs) and its corresponding plasma levels are altered in type 2 diabetes. Resistin mRNA levels were easily detectable in human PBMC, and found to be higher in DM2 compared to healthy women (P = .05). Similarly, mononuclear mRNA levels of the proinflammatory cytokines IL-1β, TNF-α, and IL-6 were all significantly higher in DM2 compared to control women (P < .001). The corresponding plasma resistin levels were slightly, but not significantly, increased in DM2 women (P = .051), and overall, they correlated significantly with BMI (r = 0.406, P = .010) and waist circumference (r = 0.516, P = .003), but not with fasting insulin levels or HOMA-IR. Resistin mRNA expression is increased in PBMC from DM2 women, together with increased expression of the inflammatory cytokines IL-1β, TNF-α, and IL-6, independent of obesity. These results suggest that resistin and cytokines might contribute to the low-grade inflammation and the increased atherogenic risk observed in these patients.

Resistin in amniotic fluid and its association with intra-amniotic infection and inflammation

OBJECTIVE

Intra-amniotic infection/inflammation (IAI) is one of the most important mechanisms of disease in preterm birth. Resistin is an adipocytokine that has been linked to insulin resistance, diabetes, obesity and inflammation. The objective of this study was to determine if resistin is present in amniotic fluid (AF) and if its concentration changes with gestational age, in the presence of labour, and in IAI in patients with spontaneous preterm labour (PTL) and intact membranes, preterm prelabour rupture of membranes (PPROM) and clinical chorioamnionitis.

STUDY DESIGN

This cross-sectional study included 648 patients in the following groups: (1) women in the mid-trimester of pregnancy (14-18 weeks) who underwent amniocentesis for genetic indications and delivered a normal neonate at term (n = 61); (2) normal pregnant women at term with (n = 49) and without (n = 50) spontaneous labour; (3) patients with an episode of PTL and intact membranes who were classified into: (a) PTL who delivered at term (n = 153); (b) PTL who delivered preterm (<37 weeks gestation) without IAI (n = 108); and (c) PTL with IAI (n = 84); (4) women with PPROM with (n = 47) and without (n = 44) IAI; and (5) patients with clinical chorioamnionitis at term with (n = 22) and without (n = 30) microbial invasion of the amniotic cavity. Resistin concentration in AF was determined by enzyme-linked immunoassay. Non-parametric statistics were used for analyses.

RESULTS

(1) Resistin was detected in all AF samples; (2) the median AF resistin concentration at term was significantly higher than in the mid-trimester (23.6 ng/mL vs. 10 ng/mL; p < 0.001); (3) among patients with PTL, the median AF resistin concentration was significantly higher in patients with IAI than in those without IAI (144.9 ng/mL vs. 18.7 ng/mL; p < 0.001) and those with PTL and intact membranes who delivered at term (144.9 ng/mL vs. 16.3 ng/mL; p < 0.001); (4) patients with PPROM with IAI had a significantly higher median AF resistin concentration than those without IAI (132.6 ng/mL vs. 13 ng/mL; p < 0.001); (5) no significant differences were observed in the median AF resistin concentration between patients with spontaneous labour at term and those at term not in labour (28.7 ng/mL vs. 23.6 ng/mL; p = 0.07); and (6) AF resistin concentration > or =37 ng/mL (derived from a receiver-operating characteristic curve) had a sensitivity of 85.4% and a specificity of 94.3% for the diagnosis of intra-amniotic inflammation.

CONCLUSIONS

Resistin is a physiologic constituent of the AF, and its concentrations in AF: (1) are significantly elevated in the presence of IAI; (2) increase with advancing gestation; and (3) do not change in the presence of spontaneous labour at term. We propose that resistin may play a role in the innate immune response against intra-amniotic infection.

Resistin-like molecule alpha enhances myeloid cell activation and promotes colitis

BACKGROUND

Resistin-like molecule (Relm) alpha is a secreted protein and a hallmark signature gene for alternatively activated macrophages. Relm-alpha is highly induced by allergic inflammatory triggers and perceived to promote tissue repair. Yet the function of Relm-alpha remains unknown.

OBJECTIVE

We sough to determine the role of Relm-alpha in dextran sodium sulfate (DSS)-induced colonic injury.

METHODS

The cellular source of Relm-alpha was determined after oral DSS-induced colitis. Retnla(-/-) mice were generated, subjected to DSS treatment, and monitored for disease progression (clinical and histopathologic features). Cytokine production in the supernatants of ex vivo colon cultures, and of LPS-stimulated macrophages incubated with Relm-alpha was assessed. Relm-alpha was administered intraperitoneally, and the cellular recruitment to the peritoneum was assessed.

RESULTS

After innate intestinal stimulation with DSS, Relm-alpha was highly expressed by eosinophils and epithelial cells. Retnla gene-targeted mice were protected from DSS-induced colitis (eg, decreased diarrhea, rectal bleeding, colon shortening, disease score, and histopathologic changes). Relm-alpha coactivated IL-6 and TNF-alpha release and inhibited IL-10 release from LPS-activated bone marrow-derived macrophages. Consistent with these finding, colon cultures of DSS-treated Retnla(-/-) mice produced decreased IL-6 and increased IL-10 ex vivo. Furthermore, Retnla(-/-) mice had substantially decreased c-Jun N-terminal kinase phosphorylation in vivo. In vivo administration of Relm-alpha initiated cellular recruitment to the peritoneum, and Relm-alpha was able to induce eosinophil chemotaxis in vitro.

CONCLUSIONS

These findings demonstrate a central proinflammatory role for Relm-alpha in colonic innate immune responses, identifying a novel pathway for regulation of macrophage activation.

Adipokines influencing metabolic and cardiovascular disease are differentially regulated in maintenance hemodialysis

Adipokines including leptin, adiponectin, visfatin, resistin, and interleukin (IL)-6 significantly influence energy metabolism, insulin sensitivity, and cardiovascular health. In the current study, we investigated serum levels of these adipokines in diabetic and nondiabetic patients on maintenance hemodialysis (MD) as compared with controls with a glomerular filtration rate greater than 50 mL/min. Serum leptin, adiponectin, high-molecular-weight (HMW) adiponectin, visfatin, resistin, and IL-6 were determined by enzyme-linked immunosorbent assay in control (n = 60) and MD (n = 60) patients and correlated to clinical and biochemical measures of renal function, glucose, and lipid metabolism, as well as inflammation. Adiponectin, visfatin, resistin, and IL-6 were significantly elevated in MD patients as compared with controls. In multivariate analyses, sex and body mass index were independently correlated with serum leptin levels in both controls and MD patients. Furthermore, insulin resistance was independently and negatively associated with adiponectin and HMW adiponectin in both groups. Moreover, circulating resistin levels were independently correlated with serum visfatin concentrations in control and MD patients. However, various independent associations were only found in either controls or patients on MD. Thus, serum IL-6 levels were strongly and independently associated with C reactive protein and resistin in MD patients but not control subjects. We show that levels of various adipokines are significantly increased in MD patients. Furthermore, regulation of adipokines in vivo strongly depends on renal function. Regulation of HMW adiponectin is similar as compared with total adiponectin in the patients studied.

Immunomodulatory effect of resistin in human dendritic cells stimulated with lipoteichoic acid from Staphylococcus aureus

Resistin is an adipokine whose physiologic role in obesity, type II diabetes mellitus, and inflammatory diseases has been a subject of debate because while it is expressed in adipocytes and adipose tissue in mouse, it is expressed in leukocytes, such as macrophages, in human. In the present study, we attempt to define the effect of resistin on human dendritic cells (DCs) derived from CD14(+) monocytes. When DCs were stimulated with lipoteichoic acid (LTA) and treated with various concentrations of resistin, antigen-uptake process and the endocytic capacity of DCs were decreased. It is intriguing that resistin attenuated cytokine production in LTA-primed DCs. Consequently, T cell activity was reduced when lymphocytes were mixed with Staphylococcus aureus-primed autologous DCs treated with resistin compared to S. aureus-primed DCs without resistin. Our results suggest that resistin interferes with the efficacy of immune responses activated by Gram-positive bacterial infection in human DCs.

Adipokines and insulin resistance

Obesity is associated with an array of health problems in adult and pediatric populations. Understanding the pathogenesis of obesity and its metabolic sequelae has advanced rapidly over the past decades. Adipose tissue represents an active endocrine organ that, in addition to regulating fat mass and nutrient homeostasis, releases a large number of bioactive mediators (adipokines) that signal to organs of metabolic importance including brain, liver, skeletal muscle, and the immune system--thereby modulating hemostasis, blood pressure, lipid and glucose metabolism, inflammation, and atherosclerosis. In the present review, we summarize current data on the effect of the adipose tissue-derived hormones adiponectin, chemerin, leptin, omentin, resistin, retinol binding protein 4, tumor necrosis factor-alpha and interleukin-6, vaspin, and visfatin on insulin resistance.

New serological biomarkers of inflammatory bowel disease

Serological biomarkers in inflammatory bowel disease (IBD) are a rapidly expanding list of non-invasive tests for objective assessments of disease activity, early diagnosis, prognosis evaluation and surveillance. This review summarizes both old and new biomarkers in IBD, but focuses on the development and characterization of new serological biomarkers (identified since 2007). These include five new anti-glycan antibodies, anti-chitobioside IgA (ACCA), anti-laminaribioside IgG (ALCA), anti-manobioside IgG (AMCA), and antibodies against chemically synthesized (Σ) two major oligomannose epitopes, Man α-1,3 Man α-1,2 Man (ΣMan3) and Man α-1,3 Man α-1,2 Man α-1,2 Man (ΣMan4). These new biomarkers serve as valuable complementary tools to existing biomarkers not only in differentiating Crohn’s disease (CD), ulcerative colitis (UC), normal and other non-IBD gut diseases, but also in predicting disease involvement (ileum vs colon), IBD risk (as subclinical biomarkers), and disease course (risk of complication and surgery). Interestingly, the prevalence of the antiglycan antibodies, including anti-Saccharomyces cerevisiae antibodies (ASCA), ALCA and AMCA, was found to be associated with single nucleotide polymorphisms (SNPs) of IBD susceptible genes such as NOD2/CARD15, NOD1/CARD4, toll-like receptors (TLR) 2 and 4, and β-defensin-1. Furthermore, a gene dosage effect was observed: anti-glycan positivity became more frequent as the number of NOD2/CARD15 SNPS increased. Other new serum/plasma IBD biomarkers reviewed include ubiquitination factor E4A (UBE4A), CXCL16 (a chemokine), resistin, and apolipoprotein A-IV. This review also discusses the most recent studies in IBD biomarker discovery by the application of new technologies such as proteomics, fourier transform near-infrared spectroscopy, and multiplex enzyme-linked immunosorbent assay (ELISA)’s (with an emphasis on cytokine/chemokine profiling). Finally, the prospects of developing more clinically useful novel diagnostic algorithms by incorporating new technologies in serological biomarker profiling and integrating multiple biomarkers with bioinformatics analysis/modeling are also discussed.

[Pathogenesis of the metabolic syndrome]

After an initial attempt by the WHO to define metabolic syndrome (MS) on a pathophysiologically oriented approach requiring the assessment of insulin resistance markers, the NCEP-ATPIII and more recently the IDF proposed more clinically oriented criteria to help, toward a preventive medicine goal, to identify patients who are likely to have features of the MS and be at increased risk of type 2 diabetes and cardio vascular disease. The notion of MS is built around abnormalities of the metabolism of lipids and carbon hydrates, a rise of blood pressure, and visceral obesity of abdominal localization. These parameters report only partially on mechanisms leading to the development of the MS. The physiopathology of MS is partially understood even today and likely results from the combination of environmental, genetic and epigenetic factors. Abdominal visceral obesity, a state of low-grade chronic inflammation and insulin resistance are the main processes susceptible to explain the various constituents of this syndrome.

Induction of angiogenesis by murine resistin: putative role of PI3-kinase and NO-dependent pathways

Adipose tissue is a highly active endocrine organ, secreting bioactive molecules, adipokines, into the circulation. Obesity results in dysregulated adipokine secretion, contributing to pathophysiologies associated with this disorder, including insulin resistance and cardiovascular disease.

OBJECTIVES

To establish whether resistin, a novel bioactive molecule produced by murine adipose tissue, and implicated in insulin resistance in rodents, can induce angiogenic responses in aortic tissues and endothelial cells in vitro, and to investigate the signal transduction pathways involved in these responses.

RESULTS

Recombinant murine resistin (5-100 ng ml(-1)) induced sprouting of cellular networks and migration from murine aortic arch explants, primary aortic endothelial cells and in a 'wound healing' model utilising murine b.End5 endothelioma cells. The increased migration and sprouting of endothelial cells, due to resistin, were blocked by wortmannin (100 nM) and LY294002 (10 microM), inhibitors of phosphatidylinositol-3-kinase (PI3K), and accompanied by PI3K-dependent phosphorylation of Akt; moreover, while the changes were not associated with altered production of nitric oxide (NO), resistin-induced angiogenic responses were inhibited by IKK Inhibitor X (5 microM), an inhibitor of activation of nuclear factor (NF)-kappaB.

CONCLUSIONS

Murine resistin induces endothelial cell migration and sprouting of cellular networks via a mechanism which appears dependent upon PI3K and NF-kappaB activity, but independent of altered NO production. Resistin may contribute to angiogenic responses sustaining adipose tissue expansion, or in arterial tissues distal to this site.

Obesity in psoriasis: leptin and resistin as mediators of cutaneous inflammation

BACKGROUND

Obesity is a significant risk factor for psoriasis and body mass index (BMI) correlates with disease severity. Objectives To investigate the relationship between obesity and psoriasis, focusing on the role of adipokines such as leptin and resistin.

PATIENTS/METHODS

Patients with psoriasis (n = 30) were recruited and their BMI, waist circumference and disease severity [Psoriasis Area and Severity Index (PASI)] were recorded. Fasting serum samples were obtained on enrolment and after a course of ultraviolet (UV) B treatment. Age-, sex- and BMI-matched healthy controls were also recruited.

RESULTS

On enrolment, serum leptin and soluble leptin receptor levels were not raised compared with the controls. However, resistin, interleukin (IL)-1beta, IL-6, and chemokines CCL2, CXCL8 and CXCL9 were all significantly elevated in the patient group and serum resistin correlated with disease severity (r = 0.372, P = 0.043). Improvement after UVB treatment was accompanied by decreased serum CXCL8. In vitro, both leptin and resistin could induce CXCL8 and tumour necrosis factor-alpha production by blood monocytes, and leptin could additionally induce IL-1beta and IL-1 receptor antagonist production. Leptin also dose dependently increased secretion of the growth factor amphiregulin by ex vivo-cultured lesional psoriasis skin.

CONCLUSIONS

These data support the view that leptin and resistin may be involved in the pathogenesis of psoriasis in overweight individuals, possibly by augmenting the cytokine expression by the inflammatory infiltrate.

The role of adipokines in liver fibrosis

Liver fibrosis is a dynamic process consisting of the chronic activation of the wound healing reaction in response to reiterated liver damage, leading to the excessive deposition of fibrillar extracellular matrix into the liver and eventually, if the cause of injury is not removed, to liver cirrhosis. The term "adipokines" identifies a group of polypeptide molecules secreted primarily by adipose tissue, which exert local, peripheral and/or central actions. Additionally to their well-established role in controlling adipose tissue physiology, adipokines have been shown to be involved in different obesity-related diseases, such as hypertension, atherosclerosis and type 2 diabetes. Accumulating data demonstrate that obesity and insulin resistance are associated with a more severe and faster progression of the fibrogenic process in different chronic liver diseases. Therefore, numerous recent studies have analyzed the role played by adipokines in the hepatic wound healing process, identifying novel roles as modulators of liver pathophysiology. This review summarizes the more significant and recent findings concerning the role played by adipocyte-derived molecules, such as leptin, adiponectin and resistin, in the liver fibrogenic process. The actions of different adipokines on the biology of liver resident cells, as well as their effects in different animal models of liver injury are discussed. The variations in the circulating levels and in the intrahepatic expression of these molecules occurring in patients with different chronic liver diseases will be also analyzed.

Resistin in serum is associated with higher levels of IL-1Ra in post-menopausal women with rheumatoid arthritis

OBJECTIVES

The aim of this study was to investigate associations between serum levels of resistin, an adipokine and markers of inflammation, bone metabolism, plasma lipids and kidney function in post-menopausal RA patients and to evaluate if HRT during 2 yrs affected resistin levels.

METHODS

Eighty-eight women were randomly allocated to receive HRT, vitamin D(3) and calcium or vitamin D(3) and calcium alone. Serum levels of resistin, IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-6 soluble receptor, TNF-alpha were measured by ELISA, markers of bone metabolism, carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and carboxyterminal propeptide of type I procollagen by RIA, ESR, CRP, Hb, creatinine and lipids by standard laboratory techniques, BMD and total lean mass (TLM) by DXA and joint destruction by Larsen score. Resistin was also measured in 42 healthy control women.

RESULTS

There was no difference in resistin concentration between patients and healthy controls. Resistin was significantly correlated with IL-1Ra, CRP, TNF-alpha, ICTP, glucocorticosteroids and Larsen score and inversely with BMD, hip and with TLM. In multiple regression analysis, IL-1Ra, TLM and use of corticosteroids remained determinants of resistin. Patients treated with HRT displayed significant increase in resistin compared with controls in the first but not the second year.

CONCLUSIONS

Resistin was associated with increased inflammation, particularly by the acute-phase reactant IL-1Ra antagonizing IL-1beta, joint destruction, glucocorticosteroids and with reduced BMD and TLM. These findings suggest resistin being a significant mediator in the inflammatory process in RA. Further studies examining the mechanisms behind the relation between resistin and IL-1Ra are encouraged. HRT does not seem to have important long-term effect on resistin.

New role of resistin in lipopolysaccharide-induced liver damage in mice

Studies in rodents suggest that the adipocytokine resistin causes insulin resistance via impairing normal insulin signaling. However, in humans, resistin may play a more important role in inflammation than in insulin resistance. Whether resistin contributes to inflammation in rodents is unclear. Therefore, the purpose of the present study was to determine the effect of resistin exposure on the basal and stimulated [lipopolysaccharide (LPS)] inflammatory response in mouse liver in vivo. Resistin alone had no major effects on hepatic expression of insulin-responsive genes, either in the presence or absence of LPS. Although it had no effect alone, resistin significantly enhanced hepatic inflammation and necrosis caused by LPS. Resistin increased expression of proinflammatory genes, e.g., plasminogen activator inhibitor (PAI)-1, and activity of mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase 1/2, caused by LPS, but had little effect on anti-inflammatory gene expression. Resistin also enhanced fibrin deposition (an index of hemostasis) caused by LPS. The increase in PAI-1 expression, fibrin deposition, and liver damage caused by LPS + resistin was almost completely prevented either by inhibiting the coagulation cascade, hirudin, or by blocking MAP kinase signaling, U0126 [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio) butadiene], indicating that these pathways play a causal role in observed enhanced liver damage caused by resistin. Taken together, the augmentation of LPS-induced liver damage caused by resistin seems to involve, at least in part, up-regulation of hepatic inflammation via mechanisms most likely involving the coagulation cascade and fibrin accumulation. These data also suggest that resistin may have proinflammatory roles in mouse liver independent of its effects on insulin signaling, analogous to previous work in humans.

Beta cells in type 2 diabetes - a crucial contribution to pathogenesis

The healthy beta-cell has an enormous capacity to adapt to conditions of higher insulin demand (e.g. in obesity, pregnancy, cortisol excess) to maintain normoglycaemia with an increase in its functional beta-cell mass. This compensates in 80-90% of individuals for insulin resistance. However, in 10-20% of individuals, the beta-cells are unable to match the demands of insulin resistance and insulin levels are relatively insufficient to maintain normal glycaemic control. This eventually leads to glucose intolerance and type 2 diabetes (T2DM). Accordingly, preservation of functional beta-cell mass has become central in the treatment of type 1 diabetes as well as T2DM. The purpose of this review is to summarize the recently described mechanisms of beta-cell death in T2DM and to postulate possible new targets for treatment.

Obesity, inflammation, and the potential application of pharmaconutrition

Obesity is an emerging problem worldwide. Hospitalized obese patients often have a worse outcome than patients of normal weight, particularly in the setting of trauma and critical care. Obesity creates a low-grade systemic inflammatory response syndrome (SIRS) that is similar (but on a much smaller scale) to gram-negative sepsis. This process involves up-regulation of systemic immunity, is characterized clinically by insulin resistance and the metabolic syndrome, and puts the patient at increased risk for organ failure, infectious morbidity, and mortality. Through lipotoxicity and cytokine dysregulation, obesity may act to prime the immune system, predisposing to an exaggerated subsequent immune response when a second clinical insult occurs (such as trauma, burns, or myocardial infarction). Specialized nutrition therapy for such patients currently consists of a hypocaloric, high-protein diet. However, this approach does not address the putative pathophysiologic mechanisms of inflammation and altered metabolism associated with obesity. A number of dietary agents such as arginine, fish oil, and carnitine may correct these problems at the molecular level. Pharmaconutrition formulas may provide exciting innovations for the nutrition therapy of the obese patient.