Beyond fat mass: exploring the role of adipokines in rheumatic diseases

Effect of non-surgical periodontal treatment on visfatin and chemerin concentration in the gingival crevicular fluid

Visfatin, as a novel adipokine, is considered to play a role in periodontal inflammation. Chemerin is another newly identified adipokine that is possible to have a role in periodontitis firstly reported in our previous study. The aim of the current study is to evaluate the gingival crevicular fluid (GCF) levels of visfatin and chemerin in periodontitis and and compare these adipokine levels with before and after non-surgical periodontal treatment. Twenty-nine patients with Stage III Grade B periodontitis and eighteen healthy subjects included in this cross-sectional cohort study. Clinical periodontal parameters and GCF were obtained from all subjects. Eight weeks after the following non-surgical periodontal treatment including scaling and root planning, samples and clinical periodontal parameters were collected again in the periodontitis group. The levels of adipokines were analyzed with standard enzyme-linked immunosorbent assay. The levels of visfatin and chemerin were statistically significantly higher at periodontitis group as compared to healthy group (P < 0.001). Although, no changes were observed in visfatin levels after periodontal treatment (P > 0.05), chemerin levels were significantly decreased (P < 0.001). Also, no differences were observed as compared to the healthy group (P > 0.05). Visfatin and chemerin may play a role in the periodontal disease process. In addition, it can be considered that the decreased chemerin levels after non-surgical periodontal treatment may play an important role for developing host modulation strategies.

Obesity as a comorbidity in children and adolescents with autoimmune rheumatic diseases

Childhood obesity is the public health issue with alarming rates recorded throughout developed world and an important modifiable health risk for developing various chronic diseases, with childhood-onset autoimmune rheumatic diseases among them also. The aim of this article was to summarize epidemiological, pathophysiological and clinical implication of obesity on juvenile idiopathic arthritis (JIA), childhood-onset systemic lupus erythematosus (cSLE), juvenile dermatomyositis (JDM), IgA vasculitis (IgAV) and Kawasaki disease (KD). We reviewed PubMed database and selected 74 relevant articles. Epidemiological data of obesity among children with autoimmune rheumatic diseases indicate an increased prevalence of it. Pathophysiological link between obesity, humoral adipokines and cytokines released from fat tissue and childhood-onset autoimmune rheumatic diseases is complex and still not entirely clear. From the clinical point of view, obesity was not associated with disease activity in JIA and cSLE, but proved to contribute on functional impairment in both diseases and affect poor treatment response in JIA patients. Early atherosclerosis and cardiovascular disease (CVD) development in obese children and adolescents with JIA, cSLE and JDM are certainly important obesity-related complications. Understanding how obesity affects children and adolescents with autoimmune rheumatic diseases may encourage clinicians to consider taking better preventive strategies in this population to improve their long-term outcome.

Inflammation and ROS in arthritis: management by Ayurvedic medicinal plants

Chronic joint inflammatory disorders like osteoarthritis and rheumatoid arthritis, which are manifested by joint dysfunction, show an upsurge in inflammation and oxidative stress. Although conventional anti-arthritic drugs are being used to relieve pain from arthritic symptoms, they usually cause severe side effects. Traditionally used Ayurvedic medicinal plants are a promising alternative for the management of arthritic symptoms, as they are safe and effective. Ayurvedic medicinal plants improve arthritic symptoms by reducing joint tenderness, joint pain, swelling, bone and cartilage damage, and increasing knee flexion, walking distance and sports activities. These beneficial effects of Ayurvedic medicinal plants on arthritis are mediated through various cellular mechanisms including inhibition of the inflammatory markers NF-κB, cytokines, adipokines, PGE2, NO, iNOS, COX-2, and MMPs and induction of antioxidant status by decreasing free radicals, lipid peroxidation, and myeloperoxidase, and increasing antioxidant enzymes, Nrf2, and HO-1. Thus, a strategy requires using these Ayurvedic medicinal plants to treat arthritis. This article describes the status of inflammation and oxidative stress in arthritic conditions. We also provide evidence that Ayurvedic medicinal plants and their bioactive components are highly effective in improving arthritic symptoms.

Qing-Luo-Yin Alleviated Monocytes/Macrophages-Mediated Inflammation in Rats with Adjuvant-Induced Arthritis by Disrupting Their Interaction with (Pre)-Adipocytes Through PPAR-γ Signaling

Background

The Chinese herbal formula Qing-Luo-Yin (QLY) has been successfully used in rheumatoid arthritis treatment for decades. It exhibits notable immune and metabolism regulatory properties. Thereby, we investigated its effects on the interplay between (pre)-adipocytes and monocytes/macrophages under adjuvant-induced arthritis (AIA) circumstances.

Methods

Fat reservoir and histological characteristics of white fat tissues (WAT) in AIA rats receiving QLY treatment were examined upon sacrifice. Metabolic parameters, clinical indicators, and oxidative stress levels were determined using corresponding kits, while mRNA/protein expression was investigated by PCR and immunoblotting methods. M1 macrophage distribution in WAT was assessed by flow cytometry. The effects of QLY on (pre)-adipocytes were further validated by experiments in vitro.

Results

Compared with normal healthy controls, body weight and circulating triglyceride were declined in AIA rats, but serological levels of free fatty acids and low-density lipoprotein cholesterol were increased. mRNA IL-1β and iNOS expression in white blood cells and rheumatoid factor, C-reactive protein, anti-cyclic citrullinated peptide antibody, MCP-1 and IL-1β production in serum/WAT were up-regulated. Obvious CD86⁺CD11b⁺ macrophages were enriched in WAT. Meanwhile, expression of PPAR-γ and SIRT1 and secretion of adiponectin and leptin in these AIA rats were impaired. QLY restored all these pathological changes. Of note, it significantly stimulated PPAR-γ expression in the treated AIA rats. Accordingly, QLY-containing serum promoted SCD-1, PPAR-γ, and SIRT1 expression in pre-adipocytes cultured in vitro. AIA rats-derived peripheral blood mononuclear cells suppressed PPAR-γ and SCD-1 expression in co-cultured pre-adipocytes, but serum from AIA rats receiving QLY treatment did not exhibit this potential. The changes on PPAR-γ expression eventually resulted in varied adipocyte differentiation statuses. PPAR-γ selective inhibitor T0070907 abrogated QLY-induced MCP-1 production decline in LPS-primed pre-adipocytes and reduced adiponectin secretion.

Conclusion

QLY was potent in promoting PPAR-γ expression and consequently disrupted inflammatory feedback in WAT by altering monocytes/macrophages polarization and adipocytes differentiation.

An Update on the Role of Leptin in the Immuno-Metabolism of Cartilage

Since its discovery in 1994, leptin has been considered as an adipokine with pleiotropic effects. In this review, we summarize the actual information about the impact of this hormone on cartilage metabolism and pathology. Leptin signalling depends on the interaction with leptin receptor LEPR, being the long isoform of the receptor (LEPRb) the one with more efficient intracellular signalling. Chondrocytes express the long isoform of the leptin receptor and in these cells, leptin signalling, alone or in combination with other molecules, induces the expression of pro-inflammatory molecules and cartilage degenerative enzymes. Leptin has been shown to increase the proliferation and activation of immune cells, increasing the severity of immune degenerative cartilage diseases. Leptin expression in serum and synovial fluid are related to degenerative diseases such as osteoarthritis (OA), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Inhibition of leptin signalling showed to have protective effects in these diseases showing the key role of leptin in cartilage degeneration.

An overview of obesity mechanisms in humans: Endocrine regulation of food intake, eating behaviour and common determinants of body weight

Obesity is one of the biggest health challenges of the 21st century, already affecting close to 700 million people worldwide, debilitating and shortening lives and costing billions of pounds in healthcare costs and loss of workability. Body weight homeostasis relies on complex biological mechanisms and the development of obesity occurs on a background of genetic susceptibility and an environment promoting increased caloric intake and reduced physical activity. The pathophysiology of common obesity links neuro-endocrine and metabolic disturbances with behavioural changes, genetics, epigenetics and cultural habits. Also, specific causes of obesity exist, including monogenetic diseases and iatrogenic causes. In this review, we provide an overview of obesity mechanisms in humans with a focus on energy homeostasis, endocrine regulation of food intake and eating behavior, as well as the most common specific causes of obesity.

Mini-Review: The Contribution of Adipokines to Joint Inflammation in Inflammatory Rheumatic Diseases

Inflammatory rheumatic diseases (IRD) are complex disorders characterized by chronic inflammation of the joints and related skeletal structures. The most common forms of IRD are rheumatoid arthritis (RA) and spondyloarthritis (SpA), including axial SpA (axSpA) and psoriatic arthritis (PsA). Obesity is a frequent comorbidity in RA and PsA, and to a lesser extend in axial SpA. The association between obesity and IRD may be explained by the release from fat tissue of several bioactive proteins, namely adipokines. Adipokines are involved in the regulation of various processes such as lipid or glucose metabolism, but also inflammation. Adipokines are interrelated with the immune system, with both innate and adaptive immune cell connections. Several adipokines with pro-inflammatory effects have been identified such as leptin, visfatin or resistin. Conversely, adiponectin and more specifically its low molecular weight isoform, is considered to have antiinflammatory properties. In this review, we discuss the contribution of adipokines to the joint inflammation of IRD, the relation they have with immune pathways of these diseases, their links with the structural impact on peripheral joints and/or axial skeleton, and also the influence they may have on the cardiometabolic risk of IRD.

Obesity and Bone Health: A Complex Link

So far, the connections between obesity and skeleton have been extensively explored, but the results are inconsistent. Obesity is thought to affect bone health through a variety of mechanisms, including body weight, fat volume, bone formation/resorption, proinflammatory cytokines together with bone marrow microenvironment. In this review, we will mainly describe the effects of adipokines secreted by white adipose tissue on bone cells, as well as the interaction between brown adipose tissue, bone marrow adipose tissue, and bone metabolism. Meanwhile, this review also reviews the evidence for the effects of adipose tissue and its distribution on bone mass and bone-related diseases, along with the correlation between different populations with obesity and bone health. And we describe changes in bone metabolism in patients with anorexia nervosa or type 2 diabetes. In summary, all of these findings show that the response of skeleton to obesity is complex and depends on diversified factors, such as mechanical loading, obesity type, the location of adipose tissue, gender, age, bone sites, and secreted cytokines, and that these factors may exert a primary function in bone health.

Adipokines in young survivors of childhood acute lymphocytic leukemia revisited: beyond fat mass

PURPOSE

This cross-sectional study evaluated the relationship between adipokines (leptin, adiponectin, visfatin, and resistin) and adiposity indexes regarding sex and cranial radiotherapy exposure among young acute lymphocytic leukemia survivors.

METHODS

A multivariate analysis of covariance (MANCOVA) was used to evaluate the joint effect of sex, cranial radiotherapy, and body mass index (BMI) z-score (model 1) or fat mass index (FMI) (model 2) on adipokines.

RESULTS

This study included 55 survivors of childhood acute lymphocytic leukemia between 15 and 23 years of age from both sexes (56.4% female); 43.6% of the sample had undergone cranial radiotherapy (18-24 Gy). The BMI z-score, the FMI, and sex (P<0.050 for all) influenced at least one adipokine, while cranial radiotherapy exposure was marginal in model 2. Parameter estimates from the MANCOVA's final model showed that the BMI z-score (β=-0.437, P=0.010) and the FMI (β=-0.209, P=0.004) negatively influenced adiponectin, while the FMI positively affected resistin (β=0.142, P=0.020). The relationship between leptin, visfatin, and the adiposity ndexes could not be established. In model 1, females presented with increased adiponectin (β=-1.014, P=0.011) and resistin (β=-1.067, P=0.002) levels; in model 2, female sex positively affected adiponectin (β=-1.515, P=0.001) and marginally influenced resistin (β=-0.707, P=0.054) levels. Cranial radiotherapy negatively determined visfatin levels in both final models (P<0.050).

CONCLUSION

Changes in body fat may be associated with adipose tissue dysfunction and should be carefully evaluated in survivors of acute lymphocytic leukemia, considering both sex and cranial radiotherapy exposure, to treat disorders that may possibly aggravate their risk for early cardiovascular disease.

The protective role of omentin-1 in IL-1β-induced chondrocyte senescence

Osteoarthritis is a common type of degenerative joint disease. Inflammation-related chondrocyte senescence plays a major role in the pathogenesis of osteoarthritis. Omentin-1 is a newly identified anti-inflammatory adipokine involved in lipid metabolism. In this study, we examined the biological function of omentin-1 in cultured chondrocytes. The presence of omentin-1 potently suppresses IL-1β-induced cellular senescence as revealed by staining with senescence-associated beta-galactosidase (SA-β-Gal). At the cellular level, omentin-1 attenuates IL-1β-induced G1 phase cell-cycle arrest. Mechanistically, we demonstrate that omentin-1 reduced IL-1β-induced expression of senescent factors including caveolin-1, p21, and PAI-1 as well as p53 acetylation through ameliorating SIRT1 reduction. Notably, silencing of SIRT1 abolishes IL-1β-induced senescence along with the induction of p21 and PAI-1, suggesting that the action of omentin-1 in chondrocytes is dependent on SIRT1. Collectively, our results revealed the molecular mechanism through which the adipokine omentin-1 exerts a beneficial effect, thereby protecting chondrocytes from senescence. Thus, omentin-1 could have clinical implication in the treatment of osteoarthritis.

Association of circulating resistin and adiponectin levels with Kawasaki disease: A meta-analysis

The present meta-analysis was performed to examine the association between circulating blood adipokine levels and Kawasaki disease (KD). Studies were identified by searching various databases, including Web of Science, EMBASE, PubMed, Wanfang and China National Knowledge Infrastructure. After the studies were pooled, the mean difference (MD) and corresponding 95% CI were calculated. Subgroup analyses and publication bias detection were also performed. The Cochrane Q test and I² statistics were performed using Review Manager software (version 5.3) to test for heterogeneity. A Begg's test was used to assess publication bias and STATA software (version 12.0) was used for statistical analysis. The results revealed that the KD group exhibited higher levels of resistin compared with those in the healthy controls or disease controls (non-KD; MD=20.76, 95% CI=16.16-25.36, P<0.001; MD=21.27, 95% CI=14.24-28.29, P<0.001, respectively). In addition, when compared with those in patients exhibiting non-coronary artery lesions (NCAL), those with coronary artery lesions (CAL) had higher levels of adiponectin and resistin (MD=1.00, 95% CI=0.06-1.96, P=0.04; MD=2.77, 95% CI=1.32-4.22, P<0.001). Furthermore, compared with those in the inactive-phase group, patients in the active-phase group exhibited higher levels of resistin (MD=17.73, 95% CI=12.82-22.65, P<0.001). In conclusion, the present meta-analysis indicated that resistin levels were elevated in patients with KD. It was also revealed that circulating resistin and adiponectin levels in the CAL group were significantly increased compared with those in patients with NCAL. Furthermore, the active group had higher levels of resistin than the inactive group. The results of these meta-analyses indicated that resistin may serve an important role in the pathogenesis of KD and may therefore be used as biomarkers for the diagnosis of KD, whereas adiponectin may only serve an important role in the pathogenesis of CAL and may therefore be used as a biomarker to distinguish CAL from NCAL.

Effects of Tocilizumab, an Anti-Interleukin-6 Receptor Antibody, on Serum Lipid and Adipokine Levels in Patients with Rheumatoid Arthritis

Patients with rheumatoid arthritis (RA) are at increased risk of cardiovascular disease. Dyslipidemia is a known adverse effect of tocilizumab (TCZ), an anti-interleukin-6 receptor antibody used in RA treatment. We aimed to assess the effect of TCZ on lipid profile and adipokine levels in RA patients. Height, weight, disease activity scores, lipid profile and atherogenic indices (AI), leptin, adiponectin, resistin, interleukin-6, and high-sensitivity C-reactive protein (CRP) were measured before and four months after initiation of TCZ in 40 RA patients and 40 healthy controls. Following TCZ treatment, total cholesterol, high density lipoprotein (HDL), and triglycerides were significantly elevated, but no significant changes in weight, body mass index (BMI), low density lipoprotein (LDL), and AI were observed. Compared with controls, significantly higher adiponectin levels were measured in the RA group at baseline. Following TCZ treatment, resistin levels and the leptin-to-adiponectin ratio increased, adiponectin levels decreased, and leptin levels remained unchanged. No correlation was found between the change in adipokine serum levels and changes in the disease activity indices, nor the lipid profile. In conclusion, the changes observed suggest a protective role for TCZ on the metabolic and cardiovascular burden associated with RA, but does not provide a mechanistic explanation for this phenomenon.

Adipokine interactions promote the pathogenesis of systemic lupus erythematosus

BACKGROUND

Adipokines are chemical mediators released from adipose tissue involved in regulation of appetite, insulin sensitivity, immune system and inflammatory responses. Adipokines contributes to low grade inflammatory response in autoimmune disease like Systemic Lupus Erythematosus (SLE) but the pathophysiology is yet not clear. The aim of this study is to understand role of adipokine interactions in SLE disease pathogenesis.

METHODS

Sixty newly diagnosed treatment naïve SLE patients fulfilling the ACR criteria and forty age-sex matched healthy subjects were enrolled in thiscase-control study. Disease activity in SLE patients was evaluated using SELENA-SLEDAI. Array of adipokines, C1q circulating immune complexes (C1q-CIC), anti-C1q, anti-ribososmal P0 (anti-RibP0) and anti-mitochondrial antibodies (AMA) levels were detected by ELISA. Antinuclear antibodies (ANA) and anti-dsDNA autoantibodieswere detected by Indirect Immunofluorescence (IIF), while antigen specificities were detected by Immunoassay blot. Serum levels of C3 and C4 complement factors were assessed by nephlometer.

RESULTS

Statistically significant elevation in progranulin, adipsin and resistin levels was seen among SLE patients when compared to healthy controls (p < 0.0001). Leptin and omentin levels were significantly reduced in SLE patients (p < 0.0001). There was no statistically significant difference in serum adiponectin, chemerin and visfatin levels when these two groups were compared (p > 0.05). Adiponectin, adipsin and resistin levels were elevated in SLE patients with renal manifestations (p < 0.05). Reduced leptin levels were significantly associated with presence of renal manifestations (p < 0.05). Adiponectin levels positively correlated with disease activity (r = 0.294, p = 0.027) whereas negatively correlated with C3 levels (r = -0.439, p = 0.0007). A positive correlation was observed between hypocomplementemia and leptin levels (p < 0.05). Leptin levels were negatively correlated with disease activity, anti-dsDNA, C1q-CIC and anti-C1q levels (p < 0.05). A significant positive correlation was observed between progranulin levels and anti-ribosomal P0 antibodies (r = 0.499, p < 0.0001).

CONCLUSION

Adipokines levels and associated clinical manifestations suggest involvement of adipokines in disease pathogenesis of SLE. SLE disease activity and complement components may suggest regulatory effect of adipokines (adiponectin and leptin) on disease pathogenesis. Further studies on adipokines in SLE patients with renal manifestations may propose them as prognostic markers in renal damage.

TRIAL REGISTRATION

NA.

Low circulating chemerin levels correlate with hepatic dysfunction and increased mortality in decompensated liver cirrhosis

Nutritional status, infections, inflammation and extrahepatic organ dysfunction are critical factors for the progression of chronic liver disease. Chemerin is an immune-metabolically and chemotactically active adipokine and we hypothesized that it is associated with disease severity and prognosis in patients with advanced decompensated cirrhosis. Therefore, we measured serum concentrations of chemerin in a prospectively characterized cohort of 80 patients with decompensated cirrhosis and ascites and assessed the associations with markers of disease severity and short-term outcome at 28 days. In a subset of patients (n = 40), ascitic fluid chemerin was determined. Advanced liver disease was associated with decreased serum but not ascitic chemerin levels. Serum chemerin correlated with markers of hepatic function (total bilirubin, albumin, INR) and inversely correlated with indicators of portal hypertension (platelet count, gastrointestinal bleeding) but not with extrahepatic organ failure and systemic inflammation. Patients presenting with acute-on-chronic liver failure or infection did not exhibit altered serum or ascitic fluid chemerin concentrations. However, serum chemerin levels below 87 ng/ml predicted an increased risk for mortality or liver transplantation within 28 days independently of MELD and infections. We conclude that low serum chemerin is an independent adverse prognostic factor in patients with advanced decompensated cirrhosis.

Leptin as an obesity marker in rheumatoid arthritis

The determination of excess of body fat mass provides a more suitable determinant of obesity in rheumatoid arthritis patients; however, body mass index (BMI) may not be accurate for the quantification of adiposity. To identify a marker of excess adiposity in women with rheumatoid arthritis (RA) using different methods for fat mass evaluation. A cross-sectional study was conducted in adult female patients with RA. Disease activity was assessed by DAS28-ESR, and obesity was determined by waist circumference (WC), BMI and dual-energy X-ray absorptiometry (DXA). The Human Bone Metabolism kit (Merck Millipore, Darmstadt, Alemanha) was used to determine the plasma levels of leptin, TNF-α, IL-6, and IL-1β by quantification of serum proteins by technical microspheres (LUMINEX, TX, USA). Adiponectin was measured by enzyme-linked immunosorbent assay sandwich kit (R&D Systems, Minneapolis, MN, USA). Eighty-nine female patients, median age of 55.4 (± 11.6) years, and median disease duration of 16.4 (± 14.9) years were included. The frequency of obesity was 33.7% according to BMI, 89.9% with WC, and 56.1% with DXA. The median serum leptin concentration was the only marker that correlated with body fat percentage according to the three methods. This correlation was positive and not influenced by DAS28, C-reactive protein, erythrocyte sedimentation rate, or inflammatory cytokines levels (IL-6, TNF-α, IL-1β). Analysis of ROC curves determined the cut-off point of 10.3 ng/mL of leptin as an obesity marker, with a sensitivity of 96.43% and a specificity of 23.81%. Serum leptin correlates positively with fat mass and is potentially useful in excess fat mass determination in clinical practice.

Mediators and Patterns of Muscle Loss in Chronic Systemic Inflammation

Besides its primary function in locomotion, skeletal muscle (SKM), which represents up to half of human's weight, also plays a fundamental homeostatic role. Through the secretion of soluble peptides, or myokines, SKM interacts with major organs involved in metabolic processes. In turn, metabolic cues from these organs are received by muscle cells, which adapt their response accordingly. This is done through an intricate intracellular signaling network characterized by the cross-talking between anabolic and catabolic pathways. A fine regulation of the network is required to protect the organism from an excessive energy expenditure. Systemic inflammation evokes a catabolic reaction in SKM known as sarcopenia. In turn this response comprises several mechanisms, which vary depending on the nature of the insult and its magnitude. In this regard, aging, chronic inflammatory systemic diseases, osteoarthritis and idiopathic inflammatory myopathies can lead to muscle loss. Interestingly, sarcopenia may persist despite remission of chronic inflammation, an issue which warrants further research. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) system stands as a major participant in muscle loss during systemic inflammation, while it is also a well-recognized orchestrator of muscle cell turnover. Herein we summarize current knowledge about models of sarcopenia, their triggers and major mediators and their effect on both protein and cell growth yields. Also, the dual action of the JAK/STAT pathway in muscle mass changes is discussed. We highlight the need to unravel the precise contribution of this system to sarcopenia in order to design targeted therapeutic strategies.

Chemerin, Resistin, and Adiponectin in Patients with Connective Tissue Diseases

Background

The exact role of cytokines in inflammation and metabolic disorders in case of connective tissue diseases (CTDs) is under discussion.

Methods

In this study, we intended to find the relationship between the selected cytokines in inflammatory and metabolic disorders in patients with CTDs (n=55) and compared the results with those of control group subjects (n=25) matched by age and body mass. We estimated their nutritional status by the bioimpedance method. The levels of basic biochemical parameters and the levels of adiponectin, resistin, and chemerin were also estimated. Multiple regressions and area under the curve in receiver operating characteristic (AUC-ROC) curve were used to find the associations of aforementioned parameters.

Results

Patients with CTDs exhibited higher levels of chemerin than that of control group subjects. We found an inverse relationship between chemerin, RBC count, and hemoglobin levels. The concentration of adiponectin inversely correlated with the levels of platelets and concentrations of glucose and triglycerides as well as the erythrocyte sedimentation rate, whereas the concentration of resistin was positively correlated with WBC count, C-reactive protein (CRP), and the amount of used oral glucocorticosteroids. The mean ± standard deviation for the AUC-ROC curve in case of chemerin was the highest (AUC-ROC=0.714, p=0.0005) than that of both resistin and adiponectin.

Conclusions

Chemerin and resistin levels are related to the inflammatory state in patients with CTDs, whereas adiponectin levels seem to be correlated with a protective effect. Chemerin can be considered as a marker differentiating a proinflammatory state present in CTDs.

Emerging role of adipokines in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by multisystem organ involvement and unclear pathogenesis. Several adipokines synthesized in the adipose tissue, including leptin, adiponectin, resistin, and chemerin, have been explored in autoimmune rheumatic diseases, especially SLE, and results suggest that these mediators may be implicated in the pathogenesis of SLE. However, the current results are controversial. In this review, we will briefly discuss the expression and possible pathogenic role of several important adipokines, including leptin, adiponectin, resistin, and chemerin in SLE.

The temporal expression of adipokines during spinal fusion

BACKGROUND CONTEXT

Adipokines are secreted by white adipose tissue and have been associated with fracture healing. Our goal was to report the temporal expression of adipokines during spinal fusion in an established rabbit model.

PURPOSE

Our goal was to report the temporal expression of adipokines during spinal fusion in an established rabbit model.

STUDY DESIGN

The study design included a laboratory animal model.

METHODS

New Zealand white rabbits were assigned to either sham surgery (n=2), unilateral posterior spinal fusion (n=14), or bilateral posterior spinal fusion (n=14). Rabbits were euthanized 1-6 and 10 weeks out from surgery. Fusion was evaluated by radiographs, manual palpation, and histology. Reverse transcription-polymerase chain reaction on the bone fusion mass catalogued the gene expression of leptin, adiponectin, resistin, and vascular endothelial growth factor (VEGF) at each time point. Results were normalized to the internal control gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (2^ΔCt), and control bone sites (2^ΔΔCt). Quantitative data were analyzed by two-factor analysis of variance (p<.05).

RESULTS

Manual palpation scores, radiograph scores, and histologic findings showed progression of boney fusion over time (p<.0003). The frequency of fusion by palpation after 4 weeks was 68.75%. Leptin expression in decortication and bone graft sites peaked at 5 weeks after the fusion procedure (p=.0143), adiponectin expression was greatest 1 week after surgery (p<.001), VEGF expression peaked at 4 weeks just after initial increases in leptin expression (p<.001), and resistin decreased precipitously 1 week after the fusion procedure (p<.001).

CONCLUSIONS

Leptin expression is likely associated with the maturation phase of bone fusion. Adiponectin and resistin may play a role early on during the fusion process. Our results suggest that leptin expression may be upstream of VEGF expression during spinal fusion, and both appear to play an important role in bone spinal fusion.

Association of adipokines, interleukin-6, and tumor necrosis factor-α concentrations with clinical characteristics and presence of spinal syndesmophytes in patients with ankylosing spondylitis: A cross-sectional study

Objective

To identify correlations of the serum leptin, adiponectin, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) concentrations with the clinical characteristics, presence of spinal syndesmophytes, and body composition in patients with ankylosing spondylitis (AS).

Methods

Forty-eight patients with AS were compared with 41 sex- and age-matched controls. Assessment included clinical characteristics and the presence of spinal syndesmophytes. The serum leptin, adiponectin, TNF-α, and IL-6 concentrations were determined. Body composition was evaluated using dual-energy X-ray absorptiometry.

Results

Patients with AS and controls had similar fat mass and lean mass. Patients with AS had higher serum TNF-α and leptin concentrations than controls (52.3 vs. 1.5 pg/mL and 17.2 vs. 9.0 µg/mL, respectively). The IL-6 and adiponectin concentrations were not significantly different between the two groups. Patients with syndesmophytes had higher leptin concentrations than those without syndesmophytes (22.1 vs. 10.9 µg/mL); this difference remained after adjustment for the body mass index.

Conclusion

Elevated leptin concentrations are associated with spinal radiographic damage in patients with AS and can serve as a biomarker. Future studies should evaluate whether leptin might be a potential target for treatments to avoid structural damage.

Adipokine Contribution to the Pathogenesis of Osteoarthritis

Recent studies have shown that overweight and obesity play an important role in the development of osteoarthritis (OA). However, joint overload is not the only risk factor in this disease. For instance, the presence of OA in non-weight-bearing joints such as the hand suggests that metabolic factors may also contribute to its pathogenesis. Recently, white adipose tissue (WAT) has been recognized not only as an energy reservoir but also as an important secretory organ of adipokines. In this regard, adipokines have been closely associated with obesity and also play an important role in bone and cartilage homeostasis. Furthermore, drugs such as rosuvastatin or rosiglitazone have demonstrated chondroprotective and anti-inflammatory effects in cartilage explants from patients with OA. Thus, it seems that adipokines are important factors linking obesity, adiposity, and inflammation in OA. In this review, we are focused on establishing the physiological mechanisms of adipokines on cartilage homeostasis and evaluating their role in the pathophysiology of OA based on evidence derived from experimental research as well as from clinical-epidemiological studies.

Visfatin is a positive predictor of bone mineral density in young survivors of acute lymphocytic leukemia

Bone mass acquisition may be compromised in survivors of childhood acute lymphocytic leukemia due to various factors, including adiposity. Fat accumulation can affect bone through the direct effect of adipokines or indirectly through the state of chronic inflammation. The aim of this study was to evaluate the effect of body composition and adipokines on bone mass in survivors of acute lymphocytic leukemia. This was a cross-sectional study of 56 survivors aged between 15 and 24 years, 44.6 % of whom received cranial radiotherapy (18-24 Gy), assessed according to body fat, lean mass, and bone mineral density (dual energy X-ray absorptiometry), computed tomography scan-derived abdominal adipose tissue, and adipokines by a multiple regression analysis. Both lumbar spine L₁-L₄ (trabecular bone) and total body (cortical bone) bone mineral density were positively correlated with visfatin (p < 0.050). Lean mass index was positively correlated, while waist-to-height ratio was negatively correlated with cortical bone (p < 0.010). Low bone mineral density for chronological age was detected in 5.4 % of patients in total body, and 8.9 % at the lumbar spine. In survivors of acute lymphocytic leukemia, visfatin may play an important role in the complex relationship between body composition and bone. At present, visfatin may represent a model for further study of bone metabolism, and could possibly explain the unknown mechanisms linking bone metabolism and cancer.

CXCL8, IL-1β and sCD200 are pro-inflammatory cytokines and their levels increase in the circulation of breast carcinoma patients

The influence of biomarkers on carcinogenesis has been investigated extensively. Whether they promote carcinogenesis or work against cancer development remains to be elucidated. To the best of our knowledge, the novel molecule cluster of differentiation 200 (CD200) has not been studied on human breast cancer subjects. The present study aimed to evaluate interleukin-1β (IL-1β), C-X-C motif chemokine ligand 8 (CXCL8), cancer antigen 15.3 (CA 15.3) and the soluble CD200 (sCD200) levels in the serum samples of breast carcinoma patients in order to predict their role in breast carcinoma. The subjects included individuals with early and advanced stage breast cancers, as well as healthy controls. Commercially available ELISA kits were used to measure the serum concentrations of sCD200, IL-1β, CXCL8, CA 15.3, C-reactive protein (CRP) and leukocyte count. A total of 130 subjects were recruited; 50 early stage cancer, 50 advanced stage and 30 control subjects. Serum sCD200, CXCL8, IL-1β and CRP levels were significantly higher in the early as well as the advanced stage breast cancer patients compared to the control group. The level of CA 15.3 was statistically different between early and advanced stage. There were significant positive correlations between IL-1β and CXCL8, and IL-1β and serum sCD200 levels in the control group. These correlations did not persist in the early or the advanced stage cancer groups except CRP and CA 15.3, but new correlations appeared between serum sCD200 level and leukocyte count for advanced stage breast cancer group. Multivariate regression correlation analysis revealed positive correlation between IL-1β and sCD200; and IL-1β and CXCL8. In conclusion, sCD200, CXCL8, CA 15.3 and IL-1β are proinflammatory molecules and their levels are influenced in breast cancer patients.

E74-like factor 3 and nuclear factor-κB regulate lipocalin-2 expression in chondrocytes

KEY POINTS

E74-like factor 3 (ELF3) is a transcription factor regulated by inflammation in different physio-pathological situations. Lipocalin-2 (LCN2) emerged as a relevant adipokine involved in the regulation of inflammation. In this study we showed for the first time the involvement of ELF3 in the control of LCN2 expression and its cooperation with nuclear factor-κB (NFκB). Our results will help to better understand of the role of ELF3, NFκB and LCN2 in the pathophysiology of articular cartilage.

ABSTRACT

E74-like factor 3 (ELF3) is a transcription factor induced by inflammatory cytokines in chondrocytes that increases gene expression of catabolic and inflammatory mediators. Lipocalin 2 (LCN2) is a novel adipokine that negatively impacts articular cartilage, triggering catabolic and inflammatory responses in chondrocytes. Here, we investigated the control of LCN2 gene expression by ELF3 in the context of interleukin 1 (IL-1)-driven inflammatory responses in chondrocytes. The interaction of ELF3 and nuclear factor-κB (NFκB) in modulating LCN2 levels was also explored. LCN2 mRNA and protein levels, as well those of several other ELF3 target genes, were determined by RT-qPCR and Western blotting. Human primary chondrocytes, primary chondrocytes from wild-type and Elf3 knockout mice, and immortalized human T/C-28a2 and murine ATDC5 cell lines were used in in vitro assays. The activities of various gene reporter constructs were evaluated by luciferase assays. Gene overexpression and knockdown were performed using specific expression vectors and siRNA technology, respectively. ELF3 overexpression transactivated the LCN2 promoter and increased the IL-1-induced mRNA and protein levels of LCN2, as well as the mRNA expression of other pro-inflammatory mediators, in human and mouse chondrocytes. We also identified a collaborative loop between ELF3 and NFκB that amplifies the induction of LCN2. Our findings show a novel role for ELF3 and NFκB in the induction of the pro-inflammatory adipokine LCN2, providing additional evidence of the interaction between ELF3 and NFκB in modulating inflammatory responses, and a better understanding of the mechanisms of action of ELF3 in chondrocytes.

Chemerin in peritoneal sepsis and its associations with glucose metabolism and prognosis: a translational cross-sectional study

BACKGROUND

Stress hyperglycaemia (SHG) is a common complication in sepsis associated with poor outcome. Chemerin is an adipocytokine associated with inflammation and impaired glucose homeostasis in metabolic diseases such as type 2 diabetes (T2D). We aimed to investigate how alterations of circulating chemerin levels and corresponding visceral adipose tissue (VAT) expression are linked to glucose metabolism and prognosis in sepsis.

METHODS

Clinical data and tissue samples were taken from a cross-sectional study including control, T2D and sepsis patients, all undergoing laparotomy. A second independent patient cohort of patients with sepsis was included to evaluate associations with prognosis. This was complemented by a murine model of peritoneal infection and a high-fat diet. We analysed circulating chemerin by enzyme-linked immunosorbent assay and VAT messenger RNA (mRNA) expression by real-time polymerase chain reaction.

RESULTS

Circulating chemerin was increased in sepsis 1.69-fold compared with controls (p = 0.012) and 1.47-fold compared with T2D (p = 0.03). Otherwise, chemerin VAT mRNA expression was decreased in patients with sepsis (p = 0.006) and in septic diabetic animals (p = 0.009). Circulating chemerin correlated significantly with intra-operative glucose (r = 0.662; p = 0.01) and in trend with fasting glucose (r = 0.528; p = 0.052). After adjusting for body mass index or haemoglobin A1c, chemerin correlated in trend with insulin resistance evaluated using the logarithmised homeostasis model assessment of insulin resistance (r = 0.539, p = 0.071; r = 0.553, p = 0.062). Chemerin was positively associated with Acute Physiology and Chronic Health Evaluation II score in patients with sepsis (p = 0.036) and with clinical severity in septic mice (p = 0.031). In an independent study population, we confirmed association of chemerin with glucose levels in multivariate linear regression analysis (β = 0.556, p = 0.013). In patients with sepsis with SHG, non-survivors had significantly lower chemerin levels than survivors (0.38-fold, p = 0.006), while in patients without SHG, non-survivors had higher chemerin levels, not reaching significance (1.64-fold, p = 0.089). No difference was apparent in patients with pre-existing T2D (p = 0.44).

CONCLUSIONS

We show, for the first time to our knowledge, that chemerin is increased in sepsis and that it associates with impaired glucose metabolism and survival in these patients. It could be further evaluated as a biomarker to stratify mortality risk of patients with SHG.

Porphyromonas gingivalis and Epstein-Barr Virus Are Associated With Increased Levels of Visfatin in Gingival Crevicular Fluid

BACKGROUND

There is little clinical information on the relationship between periodontopathogens and visfatin. The purpose of this study is to determine visfatin levels in the gingival crevicular fluid (GCF) of healthy individuals and patients with periodontitis and to investigate the possible relationship between this adipokine and the presence and levels of Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescense, and Epstein-Barr virus (EBV).

METHODS

Eighteen healthy individuals and 27 patients with periodontitis were included in this study. GCF and plaque samples were obtained from all individuals. Visfatin levels were analyzed by enzyme-linked immunosorbent assay, and the bacterial numbers were evaluated by the reverse transcription-polymerase chain reaction method.

RESULTS

In patients with periodontitis, the visfatin levels in the GCF (mean: 84.29 ng/mL; range: 63.8 to 108.9 ng/mL) were significantly higher compared with those of the healthy individuals (mean: 38.06 ng/mL; range: 13.8 to 89.02 ng/mL) (P <0.01). There was a positive correlation between the visfatin levels and P. gingivalis (r = 0.266, P <0.05), whereas no correlation was found between visfatin levels and other microorganisms. In addition, the visfatin levels were found to be higher in individuals in whom P. gingivalis was detected than for those without P. gingivalis (P <0.01). The visfatin levels were also found to be higher in individuals in whom EBV was detected (P <0.05).

CONCLUSIONS

To the best of the authors' knowledge, the present study is the first one to show the correlation of periodontopathogens and GCF visfatin levels. P. gingivalis colonization of the periodontal pockets may increase visfatin secretion. Furthermore, the presence of EBV in the plaque may be another factor that causes an increase in visfatin levels.

Association of Fat Mass and Adipokines With Foot Pain in a Community Cohort

OBJECTIVE

To determine, first, if fat mass index (FMI) or fat-free mass index (FFMI) and serum adipokines tumor necrosis factor (TNF) and interleukin-6 (IL-6) are associated with prevalent (stage 2) foot pain, and, second, if they are predictive of future (stage 3) foot pain.

METHODS

A subset of participants ages ≥50 years (n = 1,462) from the North West Adelaide Health Study were used for this study. Participants from this community cohort were asked in stage 2 (2004-2006) and stage 3 (2008-2010) if they had foot pain, aching, or stiffness. In stage 2, serum adipokines and anthropometry were measured, while body composition was analyzed with dual x-ray absorptiometry. These variables, along with comorbidities and social history, were used in logistic regression analyses to determine if FMI, FFMI, and serum adipokines were associated with foot pain.

RESULTS

Prevalent foot pain was present in 20.2% of participants, and future foot pain in 36.4%. Following multivariate modeling, the odds of having pain at stage 2 increased by 8% for each FMI unit (odds ratio [OR] 1.08, 95% confidence interval [95% CI] 1.04-1.12), while the odds of having pain at stage 3 increased by 6% for each FMI unit at stage 2 (OR 1.06, 95% CI 1.02-1.11). TNF level, IL-6 level, and FFMI were not associated with pain.

CONCLUSION

Increased FMI, but not body mass index, FFMI, or TNF or IL-6 level, was associated with both prevalent and future foot pain. These results suggest that body fat may be more important than body weight with respect to foot pain. The role played by other adipokines requires further investigation.

The role of adipocytokines in the pathogenesis of knee joint osteoarthritis

Osteoarthritis (OA) is one of the most common causes of musculoskeletal disability in the world. Traditionally, it has been thought that obesity contributes to the development and progression of OA by increased mechanical load of the joint structures. Nevertheless, studies have shown that adipose tissue-derived cytokines (adipocytokines) are a possible link between obesity and OA. Furthermore, according to recent findings, not only articular cartilage may be the main target of these cytokines but also the synovial membrane, subchondral bone and infrapatellar fat pad may be encompassed in the process of degradation. This review presents the most recent reports on the contribution of adipocytokines to the knee joint cartilage degradation, osteophyte formation, infrapatellar fat pad alterations and synovitis.

Effects of Adipokines and Insulin on Intracellular pH, Calcium Concentration, and Responses to Hypo-Osmolarity in Human Articular Chondrocytes from Healthy and Osteoarthritic Cartilage

OBJECTIVE

To evaluate the effects of adipokines and insulin on intracellular calcium concentration ([Ca(2+)]i) and pH (pHi) in human articular chondrocytes from healthy (CHC) and osteoarthritic cartilage (COC).

DESIGN

pHi and [Ca(2+)]i were measured using BCECF and Fura-2 fluorometric probes in CHC and COC under control conditions and following a hypotonic shock. The effects of interleukin-1β (IL1β), tumor necrosis factor-α (TNFα), insulin, leptin, resistin, and adiponectin were assessed.

RESULTS

pHi was lower in COC than in CHC. Only IL1β β decreased pHi in both cell types; all the agents enhanced pHi recovery following an ammonium prepulse in CHC, effect that was attenuated by Na(+)-H(+) exchanger inhibitors, but they had no effect in COC. Hypotonic shock (HTS) caused a pHi increase, which was significantly smaller in COC. All the hormones attenuated this response and the effect of IL1β was greater. The basal [Ca(2+)]i was similar in COC and CHC; IL1β, TNFα, and insulin increased the [Ca(2+)]i, but leptin, resistin, and adiponectin did not. These effects were greater in COC. This [Ca(2+)]i increase was dependent on extracellular Ca(2+) and attenuated by Na(+)-Ca(2+) exchanger inhibitors. HTS caused a [Ca(2+)]i increase, which was inhibited by transient receptor potential vanilloid blockers and attenuated by all the hormones tested with the exception of adiponectin.

CONCLUSIONS

These findings may help explain the association between obesity and osteoarthritis, in which these hormones are altered. The responses of CHC and COC are different, which suggests that a modification of pH and Ca(2+) homeostasis is part of the osteoarthritis pathophysiology.

Leptin and adiponectin in patients with systemic lupus erythematosus: clinical and laboratory correlations

OBJECTIVE

To evaluate the serum levels of leptin and adiponectin in patients with systemic lupus erythematosus (SLE) and correlate their levels with disease activity, presence of autoantibodies and clinical manifestations.

METHODS

52 women with SLE and 33 healthy women were evaluated. The patients were divided into two groups, the first with active SLE and the second with inactive SLE. Patients with SLEDAI ≥3 were considered active. Serum levels of leptin (ng/ml) and adiponectin (μg/ml) were measured by enzyme immunoassay.

RESULTS

There was a significant difference in leptin levels between SLE and controls (20.7 ± 17.1 vs. 8.0 ± 5.0 ng/mL, P <0.001), but no significant difference in adiponectin levels (87.5 ± 69.7 vs. 118.1 ± 70.6 pg/ml, P = 0.053). No significant difference in levels of leptin and adiponectin was noted between inactive and active SLE groups. There was a significant association between low levels of leptin and positivity for anticardiolipin (aCL) (P = 0.025) and lupus anticoagulant (LA) (p = 0.003) and a significant association between high levels of leptin and the presence of renal disease (p <0.001). However, there was no association between adiponectin levels with autoantibodies and clinical features in SLE patients.

CONCLUSION

Patients with SLE had elevated leptin levels, with association with renal involvement. Leptin and adiponectin were not correlated with disease activity. Low levels of leptin have been associated with the presence of LA and aCL.

Mechanisms in endocrinology: the crosstalk between thyroid gland and adipose tissue: signal integration in health and disease

Obesity and thyroid diseases are common disorders in the general population and they frequently occur in single individuals. Alongside a chance association, a direct relationship between 'thyroid and obesity' has been hypothesized. Thyroid hormone is an important determinant of energy expenditure and contributes to appetite regulation, while hormones and cytokines from the adipose tissue act on the CNS to inform on the quantity of energy stores. A continuous interaction between the thyroid hormone and regulatory mechanisms localized in adipose tissue and brain is important for human body weight control and maintenance of optimal energy balance. Whether obesity has a pathogenic role in thyroid disease remains largely a matter of investigation. This review highlights the complexity in the identification of thyroid hormone deficiency in obese patients. Regardless of the importance of treating subclinical and overt hypothyroidism, at present there is no evidence to recommend pharmacological correction of the isolated hyperthyrotropinemia often encountered in obese patients. While thyroid hormones are not indicated as anti-obesity drugs, preclinical studies suggest that thyromimetic drugs, by targeting selected receptors, might be useful in the treatment of obesity and dyslipidemia.

Plasma levels of leptin and visfatin in rheumatoid arthritis patients; is there any relationship with joint damage?

OBJECTIVE S

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disorder, primarily targeting the synovium and articular cartilage that leads to joint damage. Recent reports have suggested the role of adipocytokines in mediating joint damage; however it still is a matter of debate. The purpose of this study was to evaluate the association between serum values of adiopocytokines (leptin, visfatin) and radiographic joint damage in patients with RA.

MATERIALS AND METHODS

Fifty-four patients diagnosed with RA, based on Revised ACR Criteria 2010, with 1-5 year disease duration since diagnosis, were enrolled. Twenty-nine of patients had erosion in radiographic studies and 25patients had no erosion. Radiographic joint damages were defined according to Larsen Score. Additionally, serum levels of adipocytokines were measured and cross-sectional associations with radiographic damage were explored, adjusting for pertinent confounders.

RESULTS

The serum level of visfatin were significantly higher in patients with radiographic joint damage compared with patients with no joint damage (P=0.013). This difference remained significant after adjustment for C-reactive protein levels (P=0.008), but not after adjustment for disease duration (P=0.247). The mean leptin serum levels were not different between these two groups (P=0.903). There was a positive correlation between leptin levels and BMI (r=0.494, P<0.001). However, after adjustment for BMI, leptin levels had no difference between two groups (P=0.508).

CONCLUSION

This study revealed that visfatin levels were significantly higher in patients with radiographic joint damage dependently to disease duration. Therefore, it seems that adipocytokine may be a valuable factor in therapeutic targets in the future.

Novel immunological targets in rheumatic diseases: clues from current therapies

Many years have elapsed since the discovery of immunomodulators as effective therapeutics for the treatment of rheumatic diseases, and we are still learning about their various mechanisms of action. Here, we provide a concise overview of the most recent discoveries in this field of research, focusing in particular on signaling pathways targeted by therapeutics currently used in the clinic. We highlight areas of investigation that could potentially be explored for the development of new classes of antirheumatic drugs.

High prevalence of metabolic syndrome in Takayasu arteritis: increased cardiovascular risk and lower adiponectin serum levels

OBJECTIVE

The prevalence of metabolic syndrome (MetS) tends to be high among rheumatic patients, and cardiovascular disease is the leading cause of death in these conditions. We aimed to determine the prevalence of MetS in patients with Takayasu arteritis (TA) and its association with risk factors and adipokine and cytokine levels.

METHODS

A cross-sectional study was conducted in 45 consecutive women with TA and 47 healthy controls matched by age and body mass index.

RESULTS

The prevalence of MetS (International Diabetes Federation/American Heart Association criteria) was higher in TA compared to controls (33.34 vs 8.51%, p = 0.003). Patients with TA had a higher frequency of hypertension (p < 0.001) and dyslipidemia (p = 0.001) and higher levels of insulin (p = 0.021), homeostasis model assessment index (p = 0.024), apolipoprotein E (p = 0.029), resistin (p = 0.018), and C-reactive protein (CRP, p < 0.001) compared to healthy subjects, with similar levels of adiponectin and plasminogen activator inhibitor-1 (PAI-1; p > 0.05). Further analysis of patients with TA with and without MetS revealed a higher frequency of overweight/obesity (66.66 vs 26.66%, p = 0.022), higher Framingham score ≥ 1 (p = 0.032), and lower adiponectin levels (20.37 ± 21.16 vs 38.64 ± 22.62 μg/ml, p = 0.022) in the patients with MetS. No differences were found regarding disease duration, activity, glucocorticoid use, resistin, and PAI-1 levels in the 2 groups of patients with TA (p > 0.05). Patients with and without MetS showed no differences in cytokine levels [interleukin 12 (IL-12, IL-1a, IL-6) and tumor necrosis factor-α]. IL-6 had a positive Pearson correlation with CRP only in TA patients with MetS (r = 0.57; p = 0.050).

CONCLUSION

A high prevalence of MetS was observed in patients with TA and this comorbidity seems to identify a subgroup of overweight/obese patients with high cardiovascular risk without a significant association with disease status. Further longitudinal studies are necessary to observe the effects of controlling this modifiable risk factor in the quality of life and survival of patients with TA.

An explorative study comparing levels of soluble mediators in control and osteoarthritic synovial fluid

OBJECTIVE

Soluble mediators in synovial fluid (SF) are acknowledged as key players in the pathophysiology of osteoarthritis (OA). However, a wide-spectrum screening of such mediators in SF is currently lacking. In this study, the levels of 47 mediators in the SF of control donors and osteoarthritic (OA) patients were compared.

MATERIALS & METHODS

SF was collected from control donors (n = 16) and end-stage knee OA patients (n = 18) and analysed for 47 cytokines, chemokines and growth factors using several multiplex enzyme-linked immunosorbent assays (ELISAs). A Mann-Whitney U test was used to determine differences between OA and control controls. A principal component analysis (PCA) was performed to cluster the 47 mediators.

RESULTS

The majority of the mediators could be detected in both control and OA SF. Interleukin (IL)-6, interferon inducible protein (IP)-10, macrophage derived chemokine (MDC), platelet derived growth factor (PDGF)-AA and regulated on activation normal T cell expressed and secreted (RANTES) levels were found to be higher in OA compared to control SF (P < 0.001). Leptin, IL-13, macrophage inflammatory protein (MIP)-1β, soluble CD40 (sCD40L) levels were higher and eotaxin and granulocyte colony-stimulating factor (G-CSF) levels were lower in OA SF than in control SF, albeit borderline significant (P < 0.05). The PCA enabled identification of six clusters of mediators, which explained 76% of the variance.

CONCLUSIONS

The current study provides the first extensive profile of cytokines, chemokines and growth factors present in control and OA SF. Increased levels of mediators such as MDC and IL-6 imply involvement of inflammatory processes and might be associated with the influx of inflammatory cells in OA synovial tissue. Moreover, the performed cluster analysis indicated multiple clusters, which could indicate different pathophysiological pathways in the joint.

Metabolic syndrome in rheumatoid arthritis

Insulin resistance is an essential feature of the metabolic syndrome that has been linked to rheumatoid arthritis (RA). Understanding how inflammation arising in one tissue affects the physiology and pathology of other organs remains an unanswered question with therapeutic implications for chronic conditions including obesity, diabetes mellitus, atherosclerosis, and RA. Adipokines may play a role in the development of atherogenesis in patients with RA. Biologic therapies, such as TNF-α antagonists, that block proinflammatory cytokines have beneficial effects on the insulin resistance that is often observed in patients with RA.

Osteoarthritis of the knee: why does exercise work? A qualitative study of the literature

The effectiveness of exercise to reduce pain and improve functioning in osteoarthritis of the knee (OAk) is well substantiated. Underlying mechanisms are still under debate and better understanding of the pathways involved may contribute to more targeted treatment strategies. The present qualitative analysis of the literature aims to provide an overview of theoretical models that are put forward to explain the beneficial treatment effects of exercise in OAk. An inductive qualitative approach, based on the 'grounded theory' of Glaser and Straus, was used. Twenty-two studies emphasizing on exercise therapy for OAk, collected from three Cochrane reviews and nine guidelines of the Physiotherapy Evidence Database (PEDRO) published between 2000 and 2012, were included. The introduction and discussion parts of these papers were screened for explanations of exercise-induced benefits in OAk patients. Seventy-three key points were identified which were subdivided into 16 core theoretical concepts. Finally, 5 categories were formed: neuromuscular, peri-articular, intra-articular, psychosocial components, and general fitness and health. We referred to scientific evidence that was used in the included studies to describe and categorize the concepts. Future research on exercise in OAk should allow distinguishing the contribution of different potential pathways to the treatment effects.

Immunological functions of leptin and adiponectin

Recent years have seen several advances in our understanding of the functions of adipose tissue regarding not only the energy storage, but also the regulation of complex metabolic and endocrine functions. In this context, leptin and adiponectin, the two most abundant adipocyte products, represent one of the best example of adipocytokines involved in the control of energy expenditure, lipid and carbohydrate metabolism as well as in the regulation of immune responses. Leptin and adiponectin secretion is counter-regulated in vivo, in relation to degree of adiposity, since plasma leptin concentrations are significantly elevated in obese subjects in proportion to body mass index while adiponectin secretion decreases in relation to the amount of adipose tissue. In this review we focus on the main biological activities of leptin and adiponectin on the lipid and carbohydrate metabolism and on their contribute in regulation of innate and adaptive immune responses.