Interleukin 1 receptor antagonist (IL-1Ra) is an acute-phase protein

Adipocytokines and the metabolic syndrome among older persons with and without obesity: the InCHIANTI study

OBJECTIVES

Adipose tissue-derived inflammation may contribute to metabolic alterations and eventually to the metabolic syndrome (MetS). The purpose of this study was to: (1) examine the role of adipocytokines in the association between obesity and the MetS and (2) to determine whether the association is different in obese and non-obese persons.

DESIGN

Cross-sectional population-based InCHIANTI study.

SUBJECTS

A total of 944 community-dwelling adults aged 65 years and older living in Tuscany, Italy.

MEASUREMENTS

Obesity was defined as body mass index > or =30 kg/m2 and MetS as > or =3 of the ATP-III criteria. Circulating levels of C-reactive protein, interleukin (IL)-6, IL-1 receptor antagonist (IL-1ra), IL-18, tumour necrosis factor (TNF)-alpha R1, adiponectin, resistin and leptin were measured. Additionally, insulin resistance was determined using the homeostasis model assessment (HOMA-IR).

RESULTS

The prevalence of the MetS was 32%. Both overall and abdominal obesity were significantly associated with the MetS after adjusting for inflammatory cytokines, adipokines and lifestyle factors. After adjusting for multiple confounders and HOMA-IR, IL-1ra, TNF-alpha R1 and adiponectin (P < 0.05) remained significantly associated with the MetS. Having multiple cytokines in the highest tertile increased the likelihood of having the MetS in both obese (P for trend 0.002) and non-obese persons (P for trend 0.001) independent of insulin resistance.

CONCLUSIONS

Non-obese and obese individuals who develop an intense pro-inflammatory state may be more prone to develop the MetS than those with lower levels of inflammation.

Abrogation of NF-κB signaling in human neutrophils induces neutrophil survival through sustained p38-MAPK activation

NF-κB, an important transcription factor in the regulation of cellular inflammation, is one of the prime targets for novel anti-inflammatory therapeutics. Nowadays, anti-inflammatory therapies rely mostly on steroids, which among other effects, inhibit NF-κB activity. However, steroids have only limited efficacy in the treatment on neutrophil-driven diseases, such as COPD. Human neutrophils play an important role in the pathogenesis of COPD, and clearance of these cells by apoptosis is an effective pathway for resolution of inflammation. In this study, we tested the hypothesis that modulation of the NF-κB pathway in human neutrophils affects survival. Importantly, the pharmacological NF-κB inhibitor Bay 11-7082 inhibited NF-κB signaling in human neutrophils as expected. However, we found that complete inhibition of NF-κB activity with 10 μM Bay 11-7082 prolonged neutrophil survival significantly, which was not observed with inhibitors for other signaling pathways. Bay 11-7082-induced neutrophil survival was dependent on p38-MAPK kinase activity, as the p38 kinase activity inhibitor SB203580 abrogated this response completely. Bay 11-7082 induced rapid and sustained p38 activation that correlated with inhibited NF-κB signaling and prolonged neutrophil survival. The precise role of NF-κB in regulation of p38-MAPK activation remains to be established. Under these conditions of survival, the stability of Bcl-xL but not Mcl-1 was enhanced. Although inhibition of NF-κB leads to down-regulation of inflammatory genes in many cell types, our results illustrate that interference with basal NF-κB signaling in neutrophils as a drug target should be used with caution.

Protective effect of recombinant human IL-1Ra on CCl4-induced acute liver injury in mice

AIM: To evaluate the effects of positive regulation of recombinant human interleukin 1 receptor antagonist (rhIL-1Ra) on hepatic tissue recovery in acute liver injury in mice induced by carbon tetrachloride (CCl₄).

METHODS: Acute liver damage was induced by injecting 8-wk-old mice with CCl₄ 1 mL/kg (1:3 dilution in corn oil) intraperitoneally (ip). Survival after liver failure was assessed by injecting 8-wk-old mice with a lethal dose of CCl₄ 2.6 mL/kg (1:1 dilution in corn oil) ip. Mice were subcutaneously injected with 1 mg/kg recombinant human IL-1Ra twice a day after CCl₄ treatment for 5 d. Serum alanine amino transferase (ALT) and aspartate aminotransferase (AST) levels were determined with a commercial assay kit. Serum IL-1β, IL-1Ra levels were measured by enzyme-linked immunosorbent assay kit. Quantitative real-time polymerase chain reaction was used to determine liver IL-1β, IL-1Ra and IL-6 expression during CCl₄-induced acute liver injury. Liver sections were stained with hematoxylin-eosin. A histology-injury grading system was used to evaluate the degree of necrosis after acute liver injury. Proliferating cell nuclear antigen (PCNA) staining was used to evaluate the role of rhIL-1Ra in promoting hepatocyte proliferation.

RESULTS: Quantitative analysis showed a higher level of IL-6 mRNA expression and reduced serum AST and ALT levels in the livers of the rhIL-1Ra-treated group at the early phase of CCl₄-induced acute liver injury. Histological examination indicated a decrease in centrilobular necrotic areas in mice treated with rhIL-1Ra, and a novel role of rhIL-1Ra in promoting hepatocyte proliferation was also supported by an increase of PCNA staining. All these results, accompanied by a strong survival benefit in rhIL-1Ra-treated vs PBS-treated groups, demonstrated that rhIL-1Ra administration ameliorated the histological damage and accelerated the regeneration and recovery process of the liver.

CONCLUSION: rhIL-1Ra could be further developed as a novel therapeutic agent for the treatment of acute liver injury because of its ability to reduce hepatocellular damage and facilitate liver regeneration.

Fatigue in primary Sjögren's syndrome--a link to sickness behaviour in animals?

Interleukin-1beta (IL-1beta) is involved in the regulation of sickness behaviour in response to infection and inflammation in animals. Human fatigue can be considered an element of sickness behaviour and is a prominent and often disabling phenomenon in autoimmune diseases such as primary Sjögren's syndrome (PSS). The role of the IL-1 system in the fatigue of patients with PSS was explored. A cerebrospinal fluid (CSF) analysis of IL-1beta, IL-1Ra, and IL-1sRII was performed in 54 PSS patients and 53 control subjects. Fatigue was evaluated in the patients using the Fatigue Severity Scale (FSS) and a fatigue visual analogue scale (VAS); mood was evaluated using the Beck Depression Inventory (BDI). There were higher CSF levels of IL-1Ra pg/mL in PSS patients vs. controls (median 38.4: range 15.4-81.7 vs. 33.7: 7.3-163.1, p=0.026). Fatigue VAS scores were associated with increasing CSF levels of IL-1Ra in PSS patients (R(2)=0.11, p=0.015). In a subgroup analysis of the non-depressed PSS patients (N=37; 69%), the association between VAS scores and IL-1Ra was even stronger (R(2)=0.20, p=0.006). The positive association between VAS scores and IL-1Ra remained significant in a multiple regression analysis adjusting for age and BDI scores. Increased levels of IL-1Ra in the CSF are associated with increasing fatigue in PSS patients, indicating that the activated IL-1 system is a possible biological factor associated with fatigue.

Noradrenaline induces IL-1ra and IL-1 type II receptor expression in primary glial cells and protects against IL-1beta-induced neurotoxicity

The pro-inflammatory cytokine interleukin-1beta (IL-1beta) plays a key role in initiating an immune response within the central nervous system (CNS), and is thought to be a significant contributor to the neurodegenerative process. The actions of IL-1beta can be regulated by interleukin-1 receptor antagonist (IL-1ra), which prevents IL-1beta from acting on the IL-1 type I receptor (IL-1RI). Another negative regulator of the IL-1 system is the IL-1 type II receptor (IL-1RII); a decoy receptor that serves to sequester IL-1. Consequently, pharmacological strategies that tip the balance in favour of IL-1ra and IL-1RII may be of therapeutic benefit. Evidence suggests that the neurotransmitter noradrenaline elicits anti-inflammatory actions in the CNS, and consequently may play an endogenous neuroprotective role. Here we report that noradrenaline induces production of IL-1ra and IL-1RII from primary rat mixed glial cells. In contrast, noradrenaline did not alter IL-1beta expression, or expression of IL-1RI or the IL-1 type I receptor accessory protein (IL-1RAcp); both of which are required for IL-1 signalling. Our results demonstrate that the ability of noradrenaline to induce IL-1ra and IL-1RII is mediated via beta-adrenoceptor activation and downstream activation of protein kinase A and extracellular signal-regulated kinase (ERK). In parallel with its ability to increase IL-1ra and IL-1RII, noradrenaline prevented neurotoxicity in cortical primary neurons induced by conditioned medium from IL-1beta treated mixed glial cells. These data indicate that noradrenaline negatively regulates IL-1 system in glial cells and has neuroprotective properties in situations where IL-1 contributes to pathology.

TLR4-independent and PKR-dependent interleukin 1 receptor antagonist expression upon LPS stimulation

Dendritic cells (DCs) induce innate immune responses by recognizing bacterial LPS through TLR4 receptor complexes. In this study, we compared gene expression profiles of TLR4 knockout (TLR4(neg)) DCs and wild type (TLR4(pos)) DCs after stimulating with LPS. We found that the expression of various inflammatory genes by LPS were TLR4-independent. Among them, interleukin 1 receptor antagonist (IL-1rn) was of particular interest since IL-1rn is a potent natural inhibitor of proinflammatory IL-1. Using RT-PCR, real-time PCR, immunoblotting and ELISA, we demonstrated that IL-1rn was induced by DCs stimulated with LPS in the absence of TLR4. 2-Aminopurine, a pharmacological PKR inhibitor, completely abrogated LPS-induced expression of IL-1rn in TLR4(neg) DCs, suggesting that LPS-induced TLR4-independent expression of IL-1rn might be mediated by PKR pathways. Considering that IL-1rn is a physiological inhibitor of IL-1, TLR4-independent and PKR-dependent pathways might be crucial in counter-balancing proinflammatory effector functions of DCs resulted from TLR4-dependent activation by LPS.

Interleukin-1 receptor antagonist and incident depressive symptoms over 6 years in older persons: the InCHIANTI study

BACKGROUND

We test the hypothesis that in older persons higher plasma levels of inflammatory markers predict the development of depressive symptoms during a 6-year follow-up.

METHOD

This study is part of the InCHIANTI (Invecchiare in Chianti, aging in the Chianti area) study, a prospective population-based study of older persons. The sample consisted of 991 participants, ages 65 years and older. Serum levels of C-reactive protein, interleukin (IL)-1beta, IL-1 receptor antagonist (ra), tumor necrosis factor-alpha, IL-6, IL-6 receptor, and IL-18 were measured. Depressive symptoms were assessed at baseline and at the 3- and 6-year follow-ups with the Center for Epidemiological Studies-Depression Scale (CES-D). Depressed mood was defined as CES-D > 20. Potential confounders were baseline variables related to sociodemographic, somatic health, and functional status.

RESULTS

At baseline, IL-1ra levels were significantly higher (p = .004) in depressed compared with nondepressed participants. After adjustment for confounders, among subjects free of depression at baseline, those in the third and fourth IL-1ra quartiles compared with those in the lowest quartile had, respectively, a 2.32-fold (95% confidence interval: 1.21-4.42, p = .01) and 2.78-fold (95% confidence interval: 1.47-5.26, p = .002) higher risk of developing depressed mood during a 6-year follow-up.

CONCLUSIONS

In old age, persons with high plasma levels of IL1-ra had a higher risk of developing depressive symptoms over time. These findings suggest a potential causal role for inflammation in the development of depressive symptoms in older persons.

The role of interleukins in insulin resistance and type 2 diabetes mellitus

In the past few years, several interleukins (ILs) attracted considerable attention as potential effectors in the pathology and physiology of insulin resistance associated with type 2 diabetes mellitus (T2DM) and obesity. IL-1, a major proinflammatory cytokine, is present at increased levels in patients with diabetes mellitus, and could promote beta-cell destruction and alter insulin sensitivity. The effects of IL-1 are likely to be counteracted by IL-1 receptor antagonist protein (IL-1ra), as suggested by interventional studies in patients with T2DM who were treated with a recombinant form of this protein. However, studies in IL-1ra-deficient mice provided controversial results on the exact effect of the IL-1 signaling pathway on insulin secretion, insulin sensitivity and accumulation of adipose tissue. Likewise, IL-6 has been suggested to be involved in the development of obesity-related and T2DM-related insulin resistance. The action of IL-6 on glucose homeostasis is also complex and integrates central and peripheral mechanisms. Both experimental and clinical studies now converge to show that several ILs contribute to the pathology and physiology of T2DM through their interaction with insulin signaling pathways and beta-cell function.

Variants of the interleukin-1 receptor antagonist gene are associated with fat mass in men

CONTEXT

Immune functions seem to have connections to variations in body fat mass. Studies of knockout mice indicate that endogenous interleukin (IL)-1 can suppress mature-onset obesity.

OBJECTIVE

To systematically investigate our hypotheses that single-nucleotide polymorphisms (SNPs) and/or haplotypes variants in the IL-1 gene system are associated with fat mass.

SUBJECTS

The Gothenburg osteoporosis and obesity determinants (GOOD) study is a population-based cross-sectional study of 18-20 year-old men (n=1068), from Gothenburg, Sweden. Major findings were confirmed in elderly men (n=3014) from the Swedish part of the osteoporotic fractures in men (MrOS) multicenter population-based study.

MAIN OUTCOME MEASURE

The genotype distributions and their association with body fat mass in different compartments, measured with dual-energy X-ray absorptiometry (DXA).

RESULTS

Out of 15 investigated SNPs in the IL-1 receptor antagonist (IL1RN) gene, a recently identified 3' untranslated region C>T (rs4252041, minor allele frequency=4%) SNP was associated with the primary outcome total fat mass (P=0.003) and regional fat masses, but not with lean body mass or serum IL-1 receptor 1 (IL1RN) levels. This SNP was also associated with body fat when correcting the earlier reported IL1RN+2018 T>C (rs419598) SNP (in linkage disequilibrium with a well-studied variable number tandem repeat of 86 bp). The association between rs4252041 SNP and body fat was confirmed in the older MrOS population (P=0.03). The rs4252041 SNP was part of three haplotypes consisting of five adjacent SNPs that were identified by a sliding window approach. These haplotypes had a highly significant global association with total body fat (P<0.001). None of the other investigated members of the IL-1 gene family displayed any SNPs that have not been described previously to be significantly associated with body fat.

CONCLUSIONS

The IL1RN gene, shown to enhance obesity by suppressing IL-1 effects in experimental animals, have not [corrected] previously described gene polymorphisms and haplotypes that are associated with fat, but not lean mass in two populations of men.

Impaired counter-regulation of interleukin-1 by the soluble IL-1 receptor type II in patients with chronic liver disease

OBJECTIVE

To assess the production of the endogenous IL-1 modulators IL-1 receptor antagonist (IL-1Ra), type I and II soluble IL-1 receptors (IL-1sRI and II) in patients with chronic liver disease (CLD).

MATERIAL AND METHODS

Plasma levels of IL-1beta (IL-1beta) and IL-1 modulators were assessed in 126 CLD patients and 39 healthy controls. IL-1sRII was also measured in the supernatants of primary hepatocyte cultures.

RESULTS

Plasma IL-1sRI and IL-1Ra levels were significantly higher in cirrhotic CLD patients than in non-cirrhotic CLD patients and in controls. Levels did not depend on the etiology of CLD. Likewise, plasma IL-1beta levels were elevated in CLD patients compared with those in controls. In contrast, IL-1sRII levels did not differ between CLD patients and controls. Cultures of human primary hepatocytes showed that IL-1sRII is induced by IL-1beta, but not IL-6.

CONCLUSIONS

In cirrhotic CLD patients elevated plasma IL-1beta is not counteracted by endogenous levels of IL-1sRII, whereas high IL-1sRI is expected to neutralize the naturally occurring antagonist IL-1Ra, resulting in a dysregulation of the IL-1 system that might enhance pro-inflammatory activity of IL-1.

Increased plasma interleukin-1 receptor antagonist levels in men with visceral obesity

BACKGROUND

Adipose tissue (AT) is an important source of interleukin-1 receptor antagonist (IL-1Ra). Its expression is markedly increased in obesity.

AIMS AND METHODS

To quantify the associations of IL-1Ra with body fat distribution as well as to examine the respective contributions of IL-1Ra and visceral adiposity to the variation in some cardiometabolic risk (CMR) markers. Plasma IL-1Ra levels were measured in a sample of 117 healthy non-diabetic men (age: 44.9+/-10.1 years; body mass index (BMI): 28.8+/-4.5 kg/m(2)).

RESULTS

Plasma IL-1Ra levels correlated positively with BMI, waist girth, and visceral and subcutaneous AT (0.39 < or = r<0.48; P < 0.0001). Multiple regression analyses revealed that visceral AT was the best independent predictor of IL-1Ra levels, explaining 22% (P < 0.0001) of its variance. IL-1Ra (P < 0.05) was an independent predictor of several CMR markers including triglyceride and high-density lipoprotein (HDL) cholesterol levels, cholesterol/HDL cholesterol ratio, glucose and insulin concentrations in response to a 75 g oral glucose load, and fasting insulin levels, in addition to the expected contribution of visceral AT (P < 0.05).

CONCLUSIONS

These results suggest that elevated IL-1Ra concentrations are influenced to a greater extent by visceral than subcutaneous adiposity and that IL-1Ra is independently related to some features of CMR beyond the known contribution of visceral adiposity.

Initial description of the human NLRP3 promoter

Mutations in NLRP3 (CIAS1) are identified in a continuum of related inflammatory disorders, known as cryopyrinopathies since NLRP3 codes for the protein cryopyrin. Approximately 40% of patients with classic presentation lack mutations in the coding region of NLRP3 suggesting heterogeneity or epigenetic factors. Cryopyrin is a key regulator of proinflammatory cytokine release. Therefore, variations in the NLRP3 promoter sequence may have effects on disease state in patients with cryopyrinopathies and other inflammatory diseases. In this report, we confirmed three 5'-untranslated region splice forms with two separate transcriptional start sites, and identified potential promoter regions and six new DNA promoter variants. One variant is unique to a mutation negative cryopyrinopathy patient and increases in vitro gene expression. Additional studies can now be performed to further characterize the NLRP3 promoter and sequence variants, which will lead to better understanding of the regulation of NLRP3 expression and its role in disease.

Muscle as an endocrine organ: focus on muscle-derived interleukin-6

Skeletal muscle has recently been identified as an endocrine organ. It has, therefore, been suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert paracrine, autocrine, or endocrine effects should be classified as "myokines." Recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly different families. However, the first identified and most studied myokine is the gp130 receptor cytokine interleukin-6 (IL-6). IL-6 was discovered as a myokine because of the observation that it increases up to 100-fold in the circulation during physical exercise. Identification of IL-6 production by skeletal muscle during physical activity generated renewed interest in the metabolic role of IL-6 because it created a paradox. On one hand, IL-6 is markedly produced and released in the postexercise period when insulin action is enhanced but, on the other hand, IL-6 has been associated with obesity and reduced insulin action. This review focuses on the myokine IL-6, its regulation by exercise, its signaling pathways in skeletal muscle, and its role in metabolism in both health and disease.

Polymorphisms of the IL1-receptor antagonist gene (IL1RN) are associated with multiple markers of systemic inflammation

BACKGROUND

Circulating levels of acute phase reactant proteins such as plasma C-reactive protein (CRP) are likely influenced by multiple genes regulating the innate immune response.

METHODS AND RESULTS

We screened a set of 16 inflammation-related genes for association with CRP in a large population-based study of healthy young adults (n=1627). Results were validated in 2 independent studies (n=1208 and n=4310), including a pooled analysis of all 3 studies. In the pooled analysis, the minor allele of IL1RN 1018 (rs4251961) within the gene encoding interleukin (IL)-1 receptor antagonist (IL-1RA) was significantly associated with higher mean plasma log(CRP) level (P<1 x 10(-4)). The same IL1RN 1018 allele was associated with higher mean plasma log(IL-6) levels (P=0.004). In the pooled analysis, the minor allele of IL1RN 13888 (rs2232354) was associated with higher fibrinogen, (P=0.001). The IL1RN 1018 and 13888 variant alleles tag a clade of IL1RN haplotypes linked to allele 1 of an 86-bp VNTR polymorphism. We confirmed that the IL1RN 1018 variant (rs4251961) was associated with decreased cellular IL-1RA production ex vivo.

CONCLUSIONS

Common functional polymorphisms of the IL1RN gene are associated with several markers of systemic inflammation.

Serum levels of interleukin-1 receptor antagonist (IL-1ra) in thyroid cancer patients

BACKGROUND AND AIMS

There is growing evidence that cytokines and their antagonists are important in the pathogenesis of various malignancies. While there are several reports on interleukin-1 receptor antagonist (IL-1ra) gene polymorphism and tissue expression, there is only little data available on the impact of IL-1ra serum levels. Therefore, we performed a prospective study, analyzing IL-1ra in thyroid cancer patients.

MATERIALS AND METHODS

We measured preoperative IL-1ra serum levels of 52 consecutive patients with thyroid cancer, 15 with benign adenoma and 27 healthy volunteers. The final histological diagnosis revealed 21 patients with papillary and 8 patients with follicular carcinoma (FTC), while 12 cases of medullary and 11 cases of anaplastic carcinoma (ATC) were observed.

RESULTS

Compared to the control group, serum concentrations of IL-1ra were significantly higher in ATC and FTC patients. Concerning gender differences, this effect reached significance only in women with ATC and FTC. Except for the stage IV disease in ATC, there was no correlation between IL-1ra levels and International Union Against Cancer staging.

CONCLUSION

The findings of our study indicate that IL-1ra may play an important role in the development of ATC and FTC. Future efforts should focus on the possible application of IL-1ra as a biomarker for the above-mentioned thyroid malignancies.

In-hospital outcome of patients with acute coronary syndrome: relationship with inflammation and remodeling markers

OBJECTIVES AND METHODS

The present study was designed to evaluate the role of some inflammation [interleukin (IL)-1beta, soluble IL-1 receptor, IL-1 receptor antagonist (IL-1RA), high-sensitivity C-reactive protein (hsCRP) and fibrinogen], and remodeling markers [matrix metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2] in patients with acute coronary syndrome (ACS; 40 patients), or chronic stable angina (CSA; 40 patients) compared to age- and sex-matched healthy controls (20 subjects).

RESULTS

IL-1RA, hsCRP, fibrinogen, MMP-9, and TIMP-1 plasma levels were significantly higher in patients than in controls, whereas soluble IL-1 receptor had an opposite pattern. Among patients with ACS, hsCRP plasma levels were higher in patients with non-ST segment elevation myocardial infarction (NSTEMI) than in those with unstable angina (UA). TIMP-1 plasma levels were higher in those patients with ACS who did not respond to medical therapy (non-responsive unstable angina; NR-UA). A CRP plasma level higher than 0.86 mg/dl had a 91% positive predictive value (PPV) and 63% negative predictive value for NSTEMI (odds ratio = 6.4, 95% confidence interval = 1.5-27.4). TIMP-1 plasma level higher than 21.5 ng/ml had a 100% PPV for patients with NR-UA or NSTEMI. Binary logistic analysis confirmed TIMP-1 levels as being able to predict responsiveness to therapy.

CONCLUSIONS

In conclusion, a different biochemical pattern characterizes ACS patients: those with NR-UA show only an increase of remodeling markers, whereas ACS patients with NSTEMI have an increase of both remodeling and inflammation markers.

State of the Art Reviews: Health Benefits Related to Exercise in Patients With Chronic Low-Grade Systemic Inflammation

Today, there is substantial evidence to suggest that regular exercise has health-promoting effects, which are beyond its effect on weight control. Regular exercise offers protection against all-cause mortality, and there is evidence from randomized intervention studies that physical training is effective as a treatment in patients with chronic heart diseases, type 2 diabetes, and symptoms related with the metabolic syndrome. Chronic diseases such as cardiovascular disease and type 2 diabetes are associated with chronic low-grade systemic inflammation. This review focuses on the anti-inflammatory effects of exercise that are mediated by muscle-derived cytokines (myokines). It is suggested that myokines may be involved in mediating the health-beneficial effects of exercise and that these in particular are involved in the protection against chronic diseases associated with low-grade inflammation.

The Interleukin-1 receptor antagonist is a direct target gene of PPARalpha in liver

BACKGROUND/AIMS

The Peroxisome Proliferator-Activated Receptor (PPAR) alpha belongs to the superfamily of Nuclear Receptors and plays an important role in numerous cellular processes, including lipid metabolism. It is known that PPARalpha also has an anti-inflammatory effect, which is mainly achieved by down-regulating pro-inflammatory genes. The objective of this study was to further characterize the role of PPARalpha in inflammatory gene regulation in liver.

RESULTS

According to Affymetrix micro-array analysis, the expression of various inflammatory genes in liver was decreased by treatment of mice with the synthetic PPARalpha agonist Wy14643 in a PPARalpha-dependent manner. In contrast, expression of Interleukin-1 receptor antagonist (IL-1ra), which was acutely stimulated by LPS treatment, was induced by PPARalpha. Up-regulation of IL-1ra by LPS was lower in PPARalpha -/- mice compared to Wt mice. Transactivation and chromatin immunoprecipitation studies identified IL-1ra as a direct positive target gene of PPARalpha with a functional PPRE present in the promoter. Up-regulation of IL-1ra by PPARalpha was conserved in human HepG2 hepatoma cells and the human monocyte/macrophage THP-1 cell line.

CONCLUSIONS

In addition to down-regulating expression of pro-inflammatory genes, PPARalpha suppresses the inflammatory response by direct up-regulation of genes with anti-inflammatory properties.

Common genetic variation in the gene encoding interleukin-1-receptor antagonist (IL-1RA) is associated with altered circulating IL-1RA levels

Interleukin-1-receptor antagonist (IL-1RA) modulates the biological activity of the proinflammatory cytokine interleukin-1 (IL-1) and could play an important role in the pathophysiology of inflammatory and metabolic traits. We genotyped seven single nucleotide polymorphisms (SNPs) that capture a large proportion of common genetic variation in the IL-1RN gene in 1256 participants from the Invecchiare in Chianti study. We identified five SNPs associated with circulating IL-1RA levels with varying degrees of significance (P-value range=0.016-4.9 x 10(-5)). We showed that this association is likely to be driven by one haplotype, most strongly tagged by rs4251961. This variant is only in weak linkage disequilibrium (r(2)=0.25) with a previously reported variable number of tandem repeats polymorphism (VNTR) in intron-2 although a second variant, rs579543, that tags the VNTR (r(2)=0.91), may also be independently associated with IL-1RA levels (P=0.03). We found suggestive evidence that the C allele at rs4251961 that lowers IL-1RA levels is associated with an increased IL-1beta (P=0.03) level and may also be associated with interferon -gamma (P=0.03), alpha-2 macroglobulin (P=0.008) and adiponectin (P=0.007) serum levels. In conclusion, common variation across the IL-1RN gene is strongly associated with IL-1RA levels.

Leptin induces interleukin-1beta release from rat microglial cells through a caspase 1 independent mechanism

Leptin regulates energy balance by suppressing appetite and increasing energy expenditure through actions in the hypothalamus. Recently we demonstrated that the effects of leptin are, at least in part, mediated by the release of interleukin (IL)-1beta in the brain. Microglia constitute the major source of IL-1beta in the brain but it is not known whether these cells express leptin receptors, or respond to leptin to produce IL-1beta. Using RT-PCR and immunocytochemistry, we demonstrate that primary rat microglial cells express the short (non-signalling) and long (signalling) isoforms of the leptin receptors (Ob-R)s. Immunoassays performed on cell medium collected 24 h after leptin treatment (0.01-10 microg/mL) demonstrated a dose-dependent production and release of IL-1beta and its endogenously occurring receptor antagonist IL-1RA. In addition leptin-induced IL-1beta release occurs via a signal transducer and activator of transcription 3 (STAT3)-dependent mechanism. Western blot analysis demonstrated that leptin induced the synthesis of pro-IL-1beta in microglial cells and the release of mature 17 kDa isoform into the culture medium. Leptin-induced IL-1beta release was neither inhibited by the pan-caspase inhibitor BOC-D-FMK, nor by the caspase 1 inhibitor Ac-YVAD-CHO indicating that IL-1 cleavage is independent of caspase activity. These results confirm our earlier observations in vivo and demonstrate that microglia are an important source of IL-1beta in the brain in response to leptin.

Role of ischaemic preconditioning in liver regeneration following major liver resection and transplantation

Liver ischaemic preconditioning (IPC) is known to protect the liver from the detrimental effects of ischaemic-reperfusion injury (IRI), which contributes significantly to the morbidity and mortality following major liver surgery. Recent studies have focused on the role of IPC in liver regeneration, the precise mechanism of which are not completely understood. This review discusses the current understanding of the mechanism of liver regeneration and the role of IPC in this setting. Relevant articles were reviewed from the published literature using the Medline database. The search was performed using the keywords “liver”, “ischaemic reperfusion”, “ischaemic preconditioning”, “regeneration”, “hepatectomy” and “transplantation”. The underlying mechanism of liver regeneration is a complex process involving the interaction of cytokines, growth factors and the metabolic demand of the liver. IPC, through various mediators, promotes liver regeneration by up-regulating growth-promoting factors and suppresses growth-inhibiting factors as well as damaging stresses. The increased understanding of the cellular mechanisms involved in IPC will enable the development of alternative treatment modalities aimed at promoting liver regeneration following major liver resection and transplantation.

Interleukin-1 Receptor Antagonist Induction as an Additional Mechanism for Liver Receptor Homolog-1 to Negatively Regulate the Hepatic Acute Phase Response

The liver receptor homolog-1 (LRH-1) is an orphan nuclear receptor believed to play a key role in bile acid metabolism, cholesterol homeostasis, and intestinal cell crypt renewal. LRH-1 has recently been reported to negatively regulate the hepatic acute phase response by antagonizing, at least in part, the CCAAT/enhancer-binding protein signaling pathway. Here we have shown, using adenovirus-mediated LRH-1 overexpression and gene-silencing experiments, that the interleukin-1 receptor antagonist (IL-1RA) gene is a novel LRH-1 target gene in hepatic cells. Promoter mapping and chromatin immunoprecipitation experiments revealed that LRH-1 regulates IL-1RA gene expression under inflammatory conditions at the transcriptional level via the binding to an LRH-1 response element. Interestingly, IL-1RA induction by an intraperitoneal injection of lipopolysaccharide is significantly lower in LRH-1 heterozygous compared with wild-type mice, demonstrating the contribution of LRH-1 in IL-1RA gene regulation. Finally, RNA interference experiments indicate that LRH-1 blocks the hepatic acute phase response by, at least in part, inducing IL-1RA expression. Taken together, these results lead to the identification of IL-1RA as a novel LRH-1 target gene and demonstrate the existence of multiple mechanisms contributing to the overall anti-inflammatory properties of LRH-1 in hepatic cells.

Sarcopenic obesity and inflammation in the InCHIANTI study

The aging process is often paralleled by decreases in muscle and increases in fat mass. At the extreme these two processes lead to a condition known as "sarcopenic obesity" (Roubenoff R. Ann NY Acad Sci 904: 553-557, 2000). Research suggests that inflammatory cytokines produced by adipose tissue, especially visceral fat, accelerate muscle catabolism and thus contribute to the vicious cycle that initiates and sustains sarcopenic obesity. We tested the hypothesis that obesity and poor muscle strength, hallmarks of sarcopenic obesity, are associated with high circulating levels of proinflammatory cytokines in a random sample of the residents of two municipalities in the Chianti geographic area (Tuscany, Italy). The study sample consisted of 378 men and 493 women 65 yr and older with complete data on anthropometrics, handgrip strength, and inflammatory markers. Participants were cross-classified according to sex-specific tertiles of waist circumference and grip strength and according to a cut point for obesity of body mass index > or =30 kg/m(2). After adjusting for age, sex, education, smoking history, physical activity, and history of comorbid diseases, components of sarcopenic obesity were associated with elevated levels of IL-6, C-reactive protein, IL-1 receptor antagonist, and soluble IL-6 receptor (P < 0.05). Our findings suggest that global obesity and, to a greater extent, central obesity directly affect inflammation, which in turn negatively affects muscle strength, contributing to the development and progression of sarcopenic obesity. These results suggest that proinflammatory cytokines may be critical in both the development and progression of sarcopenic obesity.

IL-1 receptor antagonist in metabolic diseases: Dr Jekyll or Mr Hyde?

Interleukin-1 receptor antagonist (IL-1ra) has been shown to play a crucial role in the prevention of various inflammatory diseases. There is also convincing evidence that IL-1ra is able to counteract inflammatory effects of IL-1 members implicated in insulin resistance and diabetes. However, the use of knock-out animal models provides evidence to the contrary and the role of IL-1ra in obesity-linked anomalies remains controversial. This minireview gets an insight into recent findings on the implication of IL-1ra and its gene polymorphism in diabetes and obesity, discusses the potential dual effects of IL-1ra observed in different models, and comments on future directions.

Interleukin-1 receptor antagonist gene polymorphism affects the progression of chronic renal failure

End-stage renal disease (ESRD) involves an inflammatory process. Interleukin-1 receptor antagonist (IL-1Ra) and interleukin-1beta gene polymorphisms affect susceptibility to the disease in several inflammatory diseases. We investigated whether these polymorphisms are involved in ESRD by genotyping DNA from 602 dialyzed patients and 433 controls with polymerase chain reaction and digestion with restriction endonuclease. Allele 2 of the IL-1Ra VNTR polymorphism was associated with ESRD (OR=1.46, 95% CI 1.19-1.78). We also found a strong association between this allele and recurrent peritonitis in peritoneal dialysis patients. Odds ratio for the risk allele was higher compared to entire ESRD group (OR=3.6, 95% CI 1.70-7.44). The homozygosity for the allele 2 was associated with disease progression, especially in patients with diabetic nephropathy and glomerulonephritis. For the patients from these two subgroups having 2.2 genotype, the mean time from disease onset to ESRD was 1.5 and 2.2 years, respectively, compared to 6.4 and 9.8 years for those with 1.1 genotype. The IL-1Ra allele 2 is associated with ESRD in our dialyzed patients. Our results demonstrate for the first time the association of the IL-1Ra allele 2 with faster progression to ESRD. If confirmed in other populations, it might be a predictor of faster disease progression.

IL-1B and IL-1RN gene polymorphisms in rheumatoid arthritis: relationship with protein plasma levels and response to therapy

OBJECTIVES

To analyze the association of interleukin (IL-1) gene polymorphisms with susceptibility to, and severity of, rheumatoid arthritis (RA) patients, comparing them with the genotype distribution in healthy controls. Also, to assess the influence of IL1-B and IL1RN gene polymorphism on IL-1beta/IL-1Ra plasma levels and response to therapy.

PATIENTS AND METHODS

We tested the allelic distribution of IL-1B (-511 and +3953) and IL-1RN (variable number of tandem repeats) gene polymorphism in 126 RA patients and 178 healthy blood donors (HBDs). The patients were categorized into two subgroups in relation to the response to methotrexate (MTX) therapy. Group A included 70 RA patients in stable partial remission after 6 months of MTX treatment (MTX-R). Group B included 56 RA patients with active disease despite MTX therapy. This group received antitumor necrosis factor (TNF) biological drugs and were defined MTX-nonresponders (MTX-NR).

RESULTS

None of the two IL-1B (-511 and +3953) gene polymorphisms were significantly different in frequency between RA patients and healthy controls. We observed an increased frequency of the rare allele IL1RN*3 in RA patients with active disease, not responding to MTX therapy (MTX-NR) (4.5%) vs MTX-R (3.6%) and healthy controls (0.8%). Interestingly, RA patients whose genotypes included the IL1RN*long allele (haplotype long-C-T) showed the worse response to MTX. HBDs harboring the IL1RN*2/2 genotype showed significantly lower levels of plasma IL1-Ra, but comparable levels of IL-1beta with regard to subjects with the presence of the IL1RN* long allele. Furthermore, the presence of the TT IL-1B +3953 genotype was associated with lower plasma levels of IL1-Ra, both in HBDs and in RA patients. Carriers of the IL1RN*2 allele responded better to infliximab therapy.

CONCLUSIONS

The results of this study provide evidence of an association between the IL1RN*long allele and RA, the strongest association being observed in RA patients with an aggressive disease resistant to MTX treatment.

Polymorphisms of interleukin-1R receptor antagonist genes in patients with chronic hepatitis B in Iran

AIM: To investigate the relationships between polymorphisms of interleukin-1R receptor antagonist genes and susceptibility to chronic hepatitis B in Iran population.

METHODS: Genomic DNA was extracted from the peripheral blood of 80 patients with chronic hepatitis B (57 males, 23 females) aged 12-77 years (mean 36.1 ± 13.8 years) and 147 normal controls (96 males, 51 females) aged 6-75 years (mean 41 ± 18.7 years) who referred to a liver clinic of Tehran and then subjected to polymerase chain reaction (PCR) amplification. PCR products were resolved on a 3% agarose gel and stained with ethidium bromide.

RESULTS: Only three of the five kinds of polymorphism (2/2, 2/4, and 4/4) were found in this study. The frequencies of 2/2, 2/4, and 4/4 were 12.5%, 17.5%, 70% respectively in chronic hepatitis B patients and 6.8%, 24.5%, and 68.7% respectively in controls. IL-1 R allele 2 was detected in 30% of chronic hepatitis B patients and in 31.3% of controls, while IL-1 R allele 4 was detected in 87.5% of chronic hepatitis B patients and in 93.2% of controls. The frequency of IL-1R alleles 2 and 4 was detected in 21.25% and 78.75% of the patients and 19.04% and 80.96% of the controls, respectively.

CONCLUSION: Our results suggest that the carriage of IL-1R receptor antagonist alleles 2, 4, 6 may not play any role in the development of HBV infection. Large population-based studies are needed to investigate the role of IL-1 polymorphisms in the pathogenesis of developing chronic hepatitis B.

Most of the interleukin 1 receptor antagonist, cathepsin S, macrophage migration inhibitory factor, nerve growth factor, and interleukin 18 release by explants of human adipose tissue is by the non-fat cells, not by the adipocytes

The present studies were designed to compare the relative release of interleukin 1 receptor antagonist (IL-1Ra), cathepsin S, macrophage migration inhibitory factor (MIF), nerve growth factor (NGF), and interleukin 18 (IL-18) by adipocytes as compared with the non-fat cells present in subcutaneous and omental adipose tissue from morbidly obese gastric bypass patients as compared with obese abdominoplasty patients. The release of IL-1Ra, cathepsin S, and MIF by explants of human adipose tissue incubated for 48 hours averaged 6, 9, and 19 pmol/g, respectively, and was far greater than the release of NGF (0.05 pmol/g) or IL-18 (0.006 pmol/g). The release by human adipocytes of IL-1Ra, cathepsin S, and MIF was 0.13, 0.32, and 2.6 pmol/g, respectively, over 48 hours, whereas NGF release was 0.003 and IL-18 0.001 pmol/g. Only the total release of MIF by human adipose tissue explants was enhanced, whereas that of IL-18 was significantly reduced in explants from morbidly obese women. Most of (55%-73%) the release of IL-1Ra, cathepsin S, MIF, NGF, and IL-18 was by the adipose tissue matrix, whereas release by stromal-vascular (SV) cells was 3% to 28% of total release over 48 hours by the adipose tissue matrix, SV cells and adipocytes. The release of NGF by adipocytes was 42%, that of MIF was 27%, and for the other factors 15% or less of release over 48 hours by the adipose tissue matrix, SV cells, and adipocytes. Our results suggest that the non-fat cells in human adipose tissue contribute to most of the release of NGF, IL-18, IL-1Ra, cathepsin S, and MIF seen during primary culture of adipose tissue explants from obese women.

Interleukin-6 and chronic inflammation

Interleukin (IL)-6 is produced at the site of inflammation and plays a key role in the acute phase response as defined by a variety of clinical and biological features such as the production of acute phase proteins. IL-6 in combination with its soluble receptor sIL-6Rα, dictates the transition from acute to chonic inflammation by changing the nature of leucocyte infiltrate (from polymorphonuclear neutrophils to monocyte/macrophages). In addition, IL-6 exerts stimulatory effects on T- and B-cells, thus favoring chronic inflammatory responses. Strategies targeting IL-6 and IL-6 signaling led to effective prevention and treatment of models of rheumatoid arthritis and other chronic inflammatory diseases.

Interleukin-1 as a therapeutic target in acute brain injury

Interest in the interactions between the immune and central nervous systems has furthered our understanding of brain function in health and disease. Experimental and clinical studies increasingly reveal an inflammatory component in the pathophysiology of many forms of brain injury. Members of the interleukin (IL)-1 cytokine family are produced by diverse cell types within the brain and may determine the outcome of neuronal injury. This review discusses the neuroprotective potential of IL-1 inhibition in various acute neurological and neurosurgical diseases. The ILs comprise an expanding family of cytokines with diverse physiological and pathological actions, of which IL-1 is a key inflammatory mediator implicated in brain injury. IL-1 expression in the normal CNS is low, but is upregulated rapidly in response to brain injury. In experimental studies, IL-1 and its endogenous, competitive, selective antagonist, IL-1 receptor antagonist (IL-1RA), mediate neurotoxic and neuroprotective outcomes, respectively. Clinical studies support the relationship between inflammation, disease severity and poor prognosis in various neurological and neurosurgical disorders. Recombinant human (rh)IL-1RA shows modest blood–brain barrier penetrance and is safe for clinical use when administered parenterally. Evidence supporting the use of rhIL-1RA and other approaches to targeting IL-1 are discussed in relation to cerebral ischemia, seizures, subarachnoid hemorrhage and traumatic brain injury.

Adipose Tissue Has Anti-Inflammatory Properties: Focus on IL-1 Receptor Antagonist (IL-1Ra)

The formation of adipose tissue could result from abnormal metabolic processes and, at the local level, from chronic inflammatory processes such as those occurring in the synovial cavity in rheumatoid arthritis or osteoarthritis, or the peritoneal cavity in various inflammatory processes of the digestive system. Adipocytes are said to produce many hormones and proinflammatory mediators. So far, however, little attention has been paid to cytokine inhibitory molecules. Based on our observation of high levels of serum interleukin receptor antagonist (IL-1Ra) in obese patients contrasting with decreased levels after gastric bypass surgery, we found white adipose tissue (WAT) in the human system to be the main source of IL-1Ra. IL-10 was also present in WAT. Furthermore, we found that interferon-beta (IFN)-beta was the principal cytokine inducing IL-1Ra in various WAT, such as that present in the synovium. We suggest that in addition to other functions adipose tissue may give rise to a host-defense mechanism against local inflammation and that fibrotic tissue in the vicinity may further induce IL-1Ra in adipocytes via the production of IFN-beta.

No response of plasma substance P, but delayed increase of interleukin-1 receptor antagonist to acute psychosocial stress

Psychosocial stress has been shown to induce inflammatory reactions, followed by the release of immunosuppressive glucocorticoids. This may be mediated by catecholamines or other stress reactive substances such as neuropeptides or cytokines. We here set out to explore the effects of acute psychosocial stress on plasma levels of substance P (SP), a possible mediator of stress-induced inflammatory reactions, and interleukin-1 receptor antagonist (IL-1ra). Twelve healthy male subjects (mean age 27 yrs.) were subjected to the psychosocial stress test "Trier Social Stress Test" (TSST) and a resting control condition. Blood and saliva samples were taken before, as well as 1, 20, 45, and 90 min after TSST or rest, respectively. Salivary cortisol and plasma SP and IL-1ra were measured using immunoassays, salivary alpha-amylase (sAA) was measured by an enzyme kinetic method, and plasma epinephrine (E) and norepinephrine (NE) were measured by HPLC. The TSST induced immediate increases of E, NE, and sAA, and a delayed increase of free cortisol. Plasma IL-1ra showed an even further delayed peak at 90 min after stress. Plasma levels of SP did not respond to stress. No significant associations between changes of stress hormones and IL-1ra or SP were found. We conclude that substance P, epinephrine, and norepinephrine are probably not involved in mediating peripheral inflammation following psychosocial stress, at least with respect to IL-1ra. Further studies have to reveal the mechanisms involved in the stress-induced up regulation of IL-1ra.

Ischemic preconditioning modulates the expression of several genes, leading to the overproduction of IL-1Ra, iNOS, and Bcl-2 in a human model of liver ischemia-reperfusion

Ischemia triggers an inflammatory response that precipitates cell death during reperfusion. Several studies have shown that tissues are protected by ischemic preconditioning (IP) consisting of 10 min of ischemia followed by 10 min of reperfusion just before ischemia. The molecular basis of this protective effect is poorly understood. We used cDNA arrays (20K) to compare global gene expression in liver biopsies from living human liver donors who underwent IP (n=7) or not (n=7) just before liver devascularization. Microarray data were analyzed using pairedt test with a type I error rate fixed at alpha = 2.5 10(6) (Bonferroni correction). We found that 60 genes were differentially expressed (36 over- and 24 underexpressed in preconditioning group). After IP, the most significantly overexpressed gene was IL-1Ra. This was confirmed by immunoblotting. Differentially expressed were genes involved in apoptosis (NOD2, ephrin-A1, and calpain) and in the carbohydrate metabolism. A significant increase in the amount of the anti-apoptotic protein Bcl-2 in preconditioned livers but no change in the cleavage of procaspase-3, -8, and -9 was observed. We also observed an increase in the amount in the inducible nitric oxide synthase. Therefore, the benefits of IP may be associated with the overproduction of IL-1Ra, Bcl-2, and NO countering the proinflammatory and proapoptotic effects generated during ischemia-reperfusion.

The role of IL-1 and IL-1Ra in joint inflammation and cartilage degradation

Interleukin (IL)-1 is a cytokine that plays a major role in inflammatory responses in the context of infections and immune-mediated diseases. IL-1 refers to two different cytokines, termed IL-1alpha and IL-1beta, produced from two genes. IL-1alpha and IL-1beta are produced by different cell types following stimulation by bacterial products, cytokines, and immune complexes. Monocytes/macrophages are the primary source of IL-1beta. Both cytokines do not possess leader peptide sequences and do not follow a classical secretory pathway. IL-1alpha is mainly cell associated, whereas IL-1beta can be released from activated cells after cleavage of its amino-terminal region by caspase-1. IL-1 is present in the synovial tissue and fluids of patients with rheumatoid arthritis. Several in vitro studies have shown that IL-1 stimulates the production of mediators such as prostaglandin E(2), nitric oxide, cytokines, chemokines, and adhesion molecules that are involved in articular inflammation. Furthermore, IL-1 stimulates the synthesis and activity of matrix metalloproteinases and other enzymes involved in cartilage destruction in rheumatoid arthritis and osteoarthritis. The effects of IL-1 are inhibited in vitro and in vivo by natural inhibitors such as IL-1 receptor antagonist and soluble receptors. IL-1 receptor antagonist belongs to the IL-1 family of cytokines and binds to IL-1 receptors but does not induce any intracellular response. IL-1 receptor antagonist inhibits the effect of IL-1 by blocking its interaction with cell surface receptors. The use of IL-1 inhibitors in experimental models of inflammatory arthritis and osteoarthritis has provided a strong support for the role of IL-1 in the pathogeny of these diseases. Most importantly, these findings have been confirmed in clinical trials in patients with rheumatic diseases. Additional strategies aimed to block the effect of IL-1 are tested in clinical trials.

Improved diagnostic approaches to infection/sepsis detection

Sepsis is a major healthcare problem from the perspective of mortality and economics. Advances in diagnostic detection of infection and sepsis have been slow, but recent advances in both soluble biomarker detection and quantitative cellular measurements promise the availability of improved diagnostic techniques. Though the promise of cytokine measurements reaching clinical practice have not matured, procalcitonin levels are currently available in many countries and appear to offer enhanced diagnostic distinction between bacterial and viral etiologies. Cellular diagnostics is poised to enter clinical laboratory practice in the form of neutrophil CD64 measurements, which offer superior sensitivity and specificity to conventional laboratory assessment of sepsis. Neutrophil CD64 expression is negligible in the healthy state. However, it increases as part of the systemic response to severe infection or sepsis. The combination of cellular proteomics, as in the case of neutrophil CD64 quantification, and selected soluble biomarkers of the inflammatory response, such as procalcitonin or triggering receptor expressed on myeloid cells (TREM)-1, is predicted to remove the current subjectivity and uncertainty in the diagnosis and therapeutic monitoring of infection and sepsis.

Rosiglitazone induces interleukin-1 receptor antagonist in interleukin-1beta-stimulated rat synovial fibroblasts via a peroxisome proliferator-activated receptor beta/delta-dependent mechanism

OBJECTIVE

To study the potency of 2 peroxisome proliferator-activated receptor gamma (PPARgamma) agonists, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15-deoxy-PGJ(2)) and rosiglitazone, to modulate the expression of interleukin-1 receptor antagonist (IL-1Ra) in rat synovial fibroblasts.

METHODS

Levels of messenger RNA for IL-1Ra and PPAR isotypes (alpha, beta/delta, gamma) were assessed by real-time polymerase chain reaction in rat synovial fibroblasts exposed to 10 ng/ml of IL-1beta. PPAR levels were assessed by Western blotting and secreted IL-1Ra levels by immunoassay. The potency of PPARgamma agonists and the PPARbeta/delta agonist GW-501516 on IL-1Ra levels was tested in the range of 1-10 microM and at 100 pM, respectively. The contribution of PPARgamma to the effects of rosiglitazone on IL-1Ra secretion was examined either by its overexpression or by inhibition using wild-type or dominant-negative constructs and the antagonist GW-9662 (10 microM), respectively. The dominant-negative strategy was also performed to investigate the possible contribution of PPARbeta/delta and NF-kappaB activation.

RESULTS

IL-1beta-induced IL-1Ra production was increased by 10 microM rosiglitazone but was reduced dose-dependently by 15-deoxy-PGJ(2). Both agonists lowered IL-1beta secretion, but rosiglitazone alone reduced the imbalance of IL-1beta/IL-1Ra toward basal levels. Enhancement of IL-1beta-induced IL-1Ra production by rosiglitazone was not affected by PPARgamma overexpression or by its inhibition with dominant-negative PPARgamma or GW-9662. Inhibition of NF-kappaB was also ineffective against rosiglitazone but abolished the stimulating effect of IL-1beta on IL-1Ra. All PPAR isotypes were expressed constitutively in rat synoviocytes, but PPARgamma decreased dramatically upon IL-1beta exposure, whereas PPARbeta/delta remained stable. Dominant-negative PPARbeta/delta abolished the enhancement of IL-1Ra by rosiglitazone, whereas GW-501516 reproduced the effect of rosiglitazone on IL-1Ra secretion.

CONCLUSION

Rosiglitazone stimulates IL-1Ra production by a PPARbeta/delta mechanism in activated rat synovial fibroblasts, further contributing to its potential antiarthritic properties and opening new perspectives for the modulation of inflammatory genes by specific PPAR agonists in articular cells.

Intracellular IL-1 receptor antagonist type 1 inhibits IL-1-induced cytokine production in keratinocytes through binding to the third component of the COP9 signalosome

The IL-1 receptor antagonist (IL-1Ra) exists in four isoforms, three of which lack signal peptides and are primarily intracellular proteins. The biologic roles of the intracellular isoforms of IL-1Ra have remained unknown. The objective of these studies was to determine whether the major intracellular isoform of IL-1Ra 18-kDa type 1 (icIL-1Ra1), mediated unique functions inside cells. A yeast two-hybrid screen with HeLa cell lysates revealed specific binding of icIL-1Ra1, and not of the other IL-1Ra isoforms, to the third component of the COP9 signalosome complex (CSN3). This binding was confirmed by Far Western blot analysis, sedimentation on a glycerol gradient, glutathione pull-down experiments, and coimmunoprecipitation. In addition to binding specifically to CSN3, icIL-1Ra1 inhibited phosphorylation of p53, c-Jun, and IkappaB by the crude CSN-associated kinase and of p53 by recombinant protein kinase CK2 and protein kinase D, both associated with CSN3. The biologic relevance of the interaction between icIL-1Ra1 and CSN3 was demonstrated in the keratinocyte cell lines KB and A431, both possessing abundant CSN3. A431 cells exhibited high levels of icIL-1Ra1 but lacked both detectable IL-1alpha-induced IL-6 and IL-8 production and phosphorylation of p38 MAPK. KB cells displayed the opposite pattern which was reversed after transfection with icIL-1Ra1 mRNA. Inhibition of CSN3 or of icIL-1Ra1 production through gene knockdown with specific small interfering RNA in A431 cells each led to an inhibition of IL-1alpha-induced IL-6 and IL-8 production. Thus, icIL-1Ra1 exhibits unique anti-inflammatory properties inside cells through binding to CSN3 with subsequent inhibition of the p38 MAPK signal transduction pathway.

The anti-inflammatory effect of exercise

Regular exercise offers protection against all-cause mortality, primarily by protection against cardiovascular disease and Type 2 diabetes mellitus. The latter disorders have been associated with chronic low-grade systemic inflammation reflected by a two- to threefold elevated level of several cytokines. Adipose tissue contributes to the production of TNF-α, which is reflected by elevated levels of soluble TNF-α receptors, IL-6, IL-1 receptor antagonist, and C-reactive protein. We suggest that TNF-α rather than IL-6 is the driver behind insulin resistance and dyslipidemia and that IL-6 is a marker of the metabolic syndrome, rather than a cause. During exercise, IL-6 is produced by muscle fibers via a TNF-independent pathway. IL-6 stimulates the appearance in the circulation of other anti-inflammatory cytokines such as IL-1ra and IL-10 and inhibits the production of the proinflammatory cytokine TNF-α. In addition, IL-6 enhances lipid turnover, stimulating lipolysis as well as fat oxidation. We suggest that regular exercise induces suppression of TNF-α and thereby offers protection against TNF-α-induced insulin resistance. Recently, IL-6 was introduced as the first myokine, defined as a cytokine that is produced and released by contracting skeletal muscle fibers, exerting its effects in other organs of the body. Here we suggest that myokines may be involved in mediating the health-beneficial effects of exercise and that these in particular are involved in the protection against chronic diseases associated with low-grade inflammation such as diabetes and cardiovascular diseases.

Treatment with granulocyte colony-stimulating factor increases interleukin-1 receptor antagonist levels during engraftment following allogeneic stem-cell transplantation

BACKGROUND

The effect of treatment with granulocyte colony-stimulating factor (G-CSF) on interleukin-1 receptor antagonist (IL-1ra) plasma concentrations as well as the role of IL-1ra on leucocyte recovery and parameters of infection within the first 30 days after haematopietic stem-cell transplantation (HSCT) are not well known.

MATERIAL AND METHODS

Twenty-seven patients undergoing myeloablative therapy followed by allogeneic SCT for various haematological disorders were either treated with (n = 18) or without (n = 9) G-CSF. IL-1ra plasma levels were serially determined by ELISA starting at day - 1 and continued until patients were engrafted.

RESULTS

Patients receiving G-CSF had significantly shorter neutropenic periods and significantly lower mean C-reactive protein serum levels during the first 3 weeks succeeding bone marrow transplantation (BMT). Importantly, starting at day + 11 and paralleling the rise of peripheral blood leucocytes, increasing IL-1ra plasma concentrations were observed in both treatment groups. However, the magnitude of the IL-1ra surge was far greater in the G-CSF treatment group. Peak IL-1ra plasma level observed on day + 19 was 882.3 +/- 879.2 pg mL(-1) (mean +/- SD) in patients receiving G-CSF compared with 285.8 +/- 175.2 pg mL(-1) (mean +/- SD) in patients not receiving G-CSF (P = 0.0130). Furthermore, a direct correlation of IL-1ra with peripheral blood leucocytes was verified by the Spearman rank test (P = 0.0025).

CONCLUSION

Granulocyte colony-stimulating factor-mediated acceleration of neutrophil recovery following myeloablative therapy correlated with increased IL-1ra plasma concentrations. Our data suggest that IL-1ra constitutes an intrinsic component of the anti-inflammatory and neutrophil differentiating efficacy of G-CSF and, thus, IL-1ra may be required for the in vivo activity of G-CSF.

Adaptation of the endothelium to fluid flow: in vitro analyses of gene expression and in vivo implications

Biomechanical forces generated by blood flow play an important role in the pathogenesis of vascular disease. For example, regions exposed to non-uniform shear stresses develop early atherosclerotic lesions while areas exposed to uniform shear stresses are protected. A variety of in vitro flow apparatuses have been created to apply well-characterized flow patterns to endothelial cells in an effort to dissect the cellular and molecular pathways involved in these distinct processes. Recent advances in biotechnology have permitted large-scale transcriptional profiling techniques to replace candidate gene screens and have allowed the genome-wide examination of biomechanical force-induced endothelial gene expression profiles. This review provides an overview of biomechanical force-induced modulation of endothelial phenotype. It examines the effect of sustained laminar shear stress (LSS), a type of uniform shear stress, on in vitro endothelial gene expression by synthesizing data from the early candidate gene and differential display polymerase chain reaction (PCR) approaches to the numerous, recent, high throughput functional genomic analyses. These studies demonstrate that prolonged LSS regulates the expression of only a small percentage (approximately 1-5%) of endothelial genes, and this transcriptional profile produces an endothelial phenotype that is quiescent, being protected from apoptosis, inflammation and oxidative stress. These observations provide a possible molecular mechanism for the strong correlation between patterns of blood flow and the occurrence of vascular pathologies, such as atherosclerosis, in vivo.

CD14 is an acute-phase protein

The origin of soluble CD14 (sCD14) in the circulation is uncertain. To examine whether CD14 could be an acute-phase protein (APP), the levels of sCD14, IL-6, and C-reactive protein were determined by ELISA in serum and synovial fluid (SF) of patients with various arthropathies, and the regulation of CD14 synthesis was examined in liver cells. In patients with crystal-mediated or immunologically mediated arthritis (rheumatoid arthritis), serum levels of sCD14 were higher than or similar to those found in infection-mediated arthritis (reactive arthritis), precluding a relation with bacteria exposure. Levels of sCD14 were similar in SF and serum, and did not correlate with the number of SF leukocytes, excluding an important source from leukocyte membrane-bound CD14, by protease-mediated shedding. In contrast, serum levels of sCD14 in patients correlated with those of C-reactive protein, a classical APP, and IL-6, a cytokine known to regulate the synthesis of APP in the liver. Serum levels of sCD14 also correlated with disease activity in rheumatoid arthritis and reactive arthritis patients. IL-6 stimulated the production of CD14 by HepG2 hepatoma cells. By real-time PCR, the inducibility of CD14 by IL-6 was also observed at the mRNA level both in HepG2 cells and human primary hepatocytes. These in vitro results were confirmed by in vivo studies in IL-6(-/-) mice injected with turpentine, an experimental model of acute-phase response. Liver levels of CD14 mRNA increased in IL-6(+/+), but not in IL-6(-/-) mice. These results indicate that sCD14 can be considered as a type 2 APP.

Polymorphisms of interleukin-1B and interleukin-1 receptor antagonist genes in patients with chronic hepatitis B

AIM: To investigate the relationships between polymorphisms of interleukin-1B (IL-1B) promoter region -511C/T and interleukin-1 receptor antagonist gene (IL-1RN) and susceptibility to chronic hepatitis B in Chinese population.

METHODS: Genomic DNA was extracted from the peripheral blood of 190 patients with chronic hepatitis B and 249 normal controls and then subjected to polymerase chain reaction (PCR) amplification. The PCR products were digested by restriction endonuclease AvaI. The products of digestion were subjected to 20 g/L gel electrophoresis and ethidium bromide staining.

RESULTS: The frequencies of IL-1B (-511) genotypes CC, CT and TT in patients with chronic hepatitis B were 23.7%, 49.5% and 26.8%, while 26.1%, 47.4% and 26.5% respectively in controls. The results showed that there was no significant difference in the frequencies of alleles or genotypes in IL-1B between patients with chronic hepatitis B and controls. The distributions of IL-1B (-511) genotype CC were significantly different between the two subgroups (HBV-DNA ≤ 1×10³ copies/mL as subgroup I, HBV-DNA > 1×10³ copies/mL as subgroup II) of chronic hepatitis B (P = 0.029). Only four of the five kinds of polymorphism (1/1, 1/2, 2/2 and 1/4) were found in this study. The frequencies of IL-1RN genotypes 1/1, 1/2, 2/2 and 1/4 were 88.9%, 9.0%, 0.5% and 1.6% in patients with chronic hepatitis B respectively, while were 81.1%, 16.9%, 0.4% and 1.6% respectively in controls. The frequencies of genotype1/2 and IL-1RN allele 2 in patients with chronic hepatitis B were lower than those in controls (P = 0.016 and P = 0.029, respectively).

CONCLUSION: There is an association between polymorphisms of the promoter region -511C/T of IL-1B and IL-1RN intron 2 and chronic hepatitis B virus infection. Subjects with IL-1RN allele 2 may be resistant to HBV infection, and IL-1B (-511) genotype CC is closely related with HBV-DNA replication, which gives some new clues to the study of pathogenesis of chronic hepatitis B.

The active metabolite of leflunomide, A77 1726, increases the production of IL-1 receptor antagonist in human synovial fibroblasts and articular chondrocytes

Leflunomide is an immunomodulatory agent used for the treatment of rheumatoid arthritis. In this study, we investigated the effect of A77 1726 – the active metabolite of leflunomide – on the production of IL-1 receptor antagonist (IL-1Ra) by human synovial fibroblasts and articular chondrocytes. Cells were incubated with A77 1726 alone or in combination with proinflammatory cytokines. IL-1Ra production was determined by ELISA. A77 1726 alone had no effect, but in the presence of IL-1β or tumour necrosis factor-α it markedly enhanced the secretion of IL-1Ra in synovial fibroblasts and chondrocytes. The effect of A77 1726 was greatest at 100 μmol/l. In synovial fibroblasts and de-differentiated chondrocytes, A77 1726 also increased IL-1β-induced IL-1Ra production in cell lysates. Freshly isolated chondrocytes contained no significant amounts of intracellular IL-1Ra. A77 1726 is a known inhibitor of pyrimidine synthesis and cyclo-oxygenase (COX)-2 activity. Addition of exogenous uridine did not significantly modify the effect of A77 1726 on IL-1Ra production, suggesting that it was not mediated by inhibition of pyrimidine synthesis. Indomethacin increased IL-1β-induced IL-1Ra secretion in synovial fibroblasts and de-differentiated chondrocytes, suggesting that inhibition of COX-2 may indeed enhance IL-1β-induced IL-1Ra production. However, the stimulatory effect of indomethacin was consistently less effective than that of A77 1726. A77 1726 increases IL-1Ra production by synovial fibroblasts and chondrocytes in the presence of proinflammatory cytokines, and thus it may possess chondroprotective effects. The effect of A77 1726 may be partially mediated by inhibition of COX-2, but other mechanisms likely concur to stimulate IL-1Ra production.

Randomized trial of the effect of antipyresis by metamizol, propacetamol or external cooling on metabolism, hemodynamics and inflammatory response

OBJECTIVE

We investigated the metabolic, hemodynamic, and inflammatory responses of pharmacological and physical therapies aimed at reducing body temperature in febrile critically ill patients.

DESIGN AND SETTING

Open-label, randomized trial in a surgical ICU in a tertiary university hospital.

PATIENTS

Thirty analgosedated, mechanically ventilated patients with a temperature of 38.5 degrees C or higher were randomized to receive either intravenous metamizol, intravenous propacetamol, or external cooling.

MEASUREMENTS AND RESULTS

Body temperature and metabolic and hemodynamic variables were recorded at baseline and during the following 4 h. Cytokine concentrations were assessed before and 4 and 12 h after the initiation of antipyresis. Body temperature decreased significantly in all treatment groups. For a 1 degrees C temperature decrease, the energy expenditure index increased by 5% with external cooling and decreased by 7% and 8% in the metamizol and propacetamol groups, respectively. Metamizol induced a significant decrease in mean arterial pressure and urine output compared to baseline and to the other two groups. C-reactive protein increased over time, but compared to the other groups it was significantly lower in patients receiving metamizol after 4 h. Cytokine concentrations were not different among the three groups or over time, although interleukin 6 tended to decrease over time in the metamizol group.

CONCLUSIONS

Metamizol, propacetamol, and external cooling equally reduced temperature. Considering the undesirable hemodynamic effects, metamizol should not be considered the first antipyretic choice in unstable patients. Propacetamol or external cooling should be preferred, although the latter should be avoided in patients unlikely to tolerate the increased metabolic demand induced by external cooling.

Interferon beta stimulates interleukin 1 receptor antagonist production in human articular chondrocytes and synovial fibroblasts

BACKGROUND

Interferon (IFN) beta displays anti-inflammatory and immunosuppressive activity and has been considered for the treatment of rheumatoid arthritis (RA). Information about the effects of this molecule on joint cells is scarce, however.

OBJECTIVE

To investigate the effects of IFNbeta on the production of interleukin-1 receptor antagonist (IL1Ra) in human articular chondrocytes and synovial fibroblasts.

METHODS

Chondrocytes and synovial fibroblasts were stimulated with IFNbeta alone or in combination with interleukin (IL) 1beta. IL1Ra concentrations in culture supernatants and cell lysates were determined by ELISA. Expression of mRNA encoding the secreted sIL1Ra or the intracellular icIL1Ra1 isoforms was quantified by real time reverse transcriptase-polymerase chain reaction.

RESULTS

In chondrocytes, IFNbeta alone had no effect, but dose dependently enhanced the secretion of IL1Ra induced by IL1beta. Chondrocyte cell lysates contained undetectable or low levels of IL1Ra, even after stimulation with IL1beta and IFNbeta. Consistently, IL1beta and IFNbeta induced sIL1Ra mRNA expression in chondrocytes, while expression of icIL1Ra1 was not detectable. Human articular chondrocytes thus mainly produce secreted IL1Ra. In synovial fibroblasts, IFNbeta alone dose dependently increased IL1Ra secretion. In addition, IFNbeta enhanced the stimulatory effect of IL1beta on IL1Ra production. In synovial cell lysates, IFNbeta and IL1beta also increased IL1Ra levels. Consistently, IFNbeta and IL1beta induced the expression of both sIL1Ra and icIL1Ra1 mRNA in synovial fibroblasts.

CONCLUSION

IFNbeta increases IL1Ra production in joint cells, which may be beneficial in cartilage damaging diseases such as RA or osteoarthritis.