Resistin is linked to inflammation, and leptin to metabolic syndrome, in women with inflammatory arthritis

Adipokines in Rheumatoid Arthritis: Emerging Biomarkers and Therapeutic Targets

Rheumatoid arthritis (RA) is a chronic inflammatory disease manifested by joint involvement, extra-articular manifestations, and general symptoms. Adipose tissue, previously perceived as an inert energy storage organ, has been recognised as a significant contributor to RA pathophysiology. Adipokines modulate immune responses, inflammation, and metabolic pathways in RA. Although most adipokines have a pro-inflammatory and aggravating effect on RA, some could counteract this pathological process. The coexistence of RA and sarcopenic obesity (SO) has gained attention due to its impact on disease severity and outcomes. Sarcopenic obesity further contributes to the inflammatory milieu and metabolic disturbances. Recent research has highlighted the intricate crosstalk between adipose tissue and skeletal muscle, suggesting potential interactions between these tissues in RA. This review summarizes the roles of adipokines in RA, particularly in inflammation, immune modulation, and joint destruction. In addition, it explores the emerging role of adipomyokines, specifically irisin and myostatin, in the pathogenesis of RA and their potential as therapeutic targets. We discuss the therapeutic implications of targeting adipokines and adipomyokines in RA management and highlight the challenges and future directions for research in this field.

Metabolic Syndrome, Disease Activity, and Adipokines in Patients With Newly Diagnosed Inflammatory Joint Diseases

OBJECTIVE

To investigate metabolic syndrome (MetS), disease activity, and adipokine levels among patients with rheumatoid arthritis (RA), spondyloarthritis (SpA), and undifferentiated arthritis (UA) at the time of diagnosis and after 1 year of follow-up.

METHODS

Patients with inflammatory joint diseases participating in the Northern Savo 2010 population-based longitudinal epidemiological study were evaluated for components of MetS (by National Cholesterol Education Program's Adult Treatment Panel III) and clinical parameters of disease activity. The adipokines adiponectin, adipsin, resistin, and leptin were measured at baseline and after 1 year of treatment with disease-modifying antirheumatic drugs.

RESULTS

Among 176 patients, MetS was detected in 42% of RA, 36% of SpA, and 51% of UA patients. Metabolic syndrome was associated with higher disease activity as measured by patient global assessment in RA and UA patients and increased pain in RA patients. Leptin levels were increased in patients with MetS, showing a linearly increasing trend with the number of components of MetS in SpA and UA, but not in RA. In RA patients, decrease in disease activity correlated with decrease in leptin levels. Resistin did not associate with MetS, but a decrease in resistin correlated with decrease in disease activity in RA and UA. In SpA, increased adiponectin level correlated with relief in disease activity, but not with MetS.

CONCLUSIONS

Metabolic syndrome was common in patients with newly diagnosed arthritides and associated with higher disease activity and increased leptin levels. Resistin responded to treatment of arthritis in RA and UA, leptin in RA, and adiponectin in SpA.

Pretreatment resistin levels are associated with erosive disease in early rheumatoid arthritis treated with disease-modifying anti-rheumatic drugs and infliximab

Objective: Resistin is an adipocytokine related to insulin resistance and inflammation. We investigated whether resistin is associated with disease activity and inflammation in disease-modifying anti-rheumatic drug (DMARD)-naïve rheumatoid arthritis (RA) patients, whether it has predictive value for radiological disease progression, and whether tumour necrosis factor-α (TNF-α) is involved in these effects.Method: Ninety-nine patients with early, DMARD-naïve RA participated in the NEO-RACo study. Patients were treated for the first 4 weeks with a combination of methotrexate, sulfasalazine, hydroxychloroquine, and prednisolone (FIN-RACo treatment). Thereafter, they were randomized to receive either infliximab or placebo added to the combination for 6 months. Patients were followed for 5 years. Disease activity was evaluated using the Disease Activity Score based on 28-joint count-erythrocyte sedimentation rate, radiographs were scored with the modified Sharp-van der Heijde method, and plasma resistin concentrations were measured by immunoassay. Human THP-1 macrophages were used in the in vitro studies.Results: A high resistin level at baseline was associated with active inflammatory disease and predicted more rapid radiological progression during 5 year follow-up. Adding infliximab to the DMARD combination delayed radiological progression and overcame the poor predictive value of resistin. Resistin increased TNF-α production in human macrophages, indicating a possible connection between resistin and TNF-α.Conclusion: The results suggest that high resistin concentration may be a useful marker to distinguish patients with an increased risk of erosive disease in early active RA, and that adding TNF-α antagonist to the traditional DMARD combination may delay radiological progression of the disease in these patients.The study has been registered at https://www.clinicaltrials.gov (NCT00908089).

Resistin is Associated with Inflammation and Renal Function, but not with Insulin Resistance in Type 2 Diabetes

The aim of the study was to investigate the association of adipokines (resistin, leptin and adiponectin) with obesity, insulin resistance (IR) and inflammation in type 2 diabetes mellitus (T2DM). A total of 284 patients with T2DM were included. Concentrations of resistin, leptin, adiponectin, and inflammatory markers [high sensitivity C-reactive protein (hsCRP), tumor necrosis factor α (TNF-α), and interleukin 6 (IL-6)] were measured and homeostatic model assessment for IR (HOMA-IR) index was calculated. Resistin correlated negatively with estimated glomerular filtration rate (eGFR) and positively with hsCRP, TNF-α, IL-6, and white blood cell count (WBC). Leptin correlated positively with HOMA-IR, whereas adiponectin correlated negatively. Leptin also correlated positively with body mass index (BMI), waist circumference, IL-6, WBC and negatively with eGFR. Adiponectin correlated negatively with waist circumference, WBC, and eGFR. Multivariate logistic regression indicated lower eGFR and higher WBC and IL-6 as independent predictive factors of resistin concentration above the upper quartile (CAQ3), whereas female sex and higher BMI and HOMA-IR of leptin CAQ3, and lower HOMA-IR and older age of adiponectin CAQ3. In conclusion, in contrast to leptin and adiponectin, in T2DM patients, resistin is not associated with BMI and IR, but with inflammation and worse kidney function.

Assessment of Adipokines, CXCL16 Chemokine Levels in Patients With Rheumatoid Arthritis Combined With Metabolic Syndrome

Objective:

Rheumatoid arthritis (RA), which is a chronic systemic inflammatory disease, is associated with accelerated atherosclerosis and an increased risk of cardiovascular disease (CVD), but the causal factors have yet to be completely elucidated. The studies show that the prevalence of metabolic syndrome (MtS) was significantly higher in RA patients compared to the population. In RA and MetS inflammation and atherosclerosis are closely linked. The level of chemokines and adipokines, which may play a role in the development of atherogenesis in RA with MetS patients is currently unknown. In this study, we investigated the level of chemokine C-X-C motif chemokine ligand 16 (CXCL16) and adipokine in RA with MetS patients and assessed the association of biomarkers with clinical and biochemical activity scores of RA and components of MetS.

Methods:

Blood serum of 298 people (48—patients with RA and MetS, 82—with RA without MetS, 105—with MetS, 63—control group without both RA and MetS) was tested for (CXCL16), Resistin, Leptin and Fibroblast Growth Factor 21 (FGF21) levels by fluorescent antibody technique. Statistical analysis was performed using SPSS version 18.0.

Results:

The biomarker study showed the highest level in the RA with MetS patient group; but as compared with the RA group the differences were insignificant. CXCL16 (Me = 426.2 pg/ml (Q_25-75 250.5-527.6), resistin (Me = 8685.4 pg/ml (Q_25-75 6480.8-13 629.1), and FGF21 (Me = 443.6 pg/ml (Q_25-75 772.9-916.3) proved to be significantly augmented in RA with MetS patients group, and in RA without MetS patients group (Me = 312.7 (Q_25-75 199.4-517.7) pg/ml; Me = 8265.3 (Q_25-75 5779.7-13 340.5) pg/ml; Me = 412.4 (Q_25-75 300.4-497.4) pg/ml, respectively) as compared with MetS patients group (Me = 189.4 (Q_25-75 130.3-280.6) pg/ml; Me = 5364.8 (Q_25-75 2368.9-10 160.9) pg/ml; Me = 133.2 (Q_25-75 76.2-268.6) pg/ml, respectively; P = <.001). Leptin level in all groups was higher than in the control group, but there were no differences between groups. The correlation analysis found a positive relationship between the leptin level and the waist circumference (rs = 0.39; P = .007) in the RA with MetS patients, the association of biomarkers with DAS28 score and ESR did not have any statistical significance. Conclusions: The augmented chemokine, resistin and FGF21 in the RA with MetS patients proves the systemic inflammation which is the basis of RA; the augmented leptin is linked to the abdominal obesity. These data are somewhat of an explanation of the increased risk of the CVD development in RA with MetS people. A differentiated specification can be useful to assess the cardiovascular risk of patients and justify prompt personalized treatment.

The Adipokine Network in Rheumatic Joint Diseases

Rheumatic diseases encompass a diverse group of chronic disorders that commonly affect musculoskeletal structures. Osteoarthritis (OA) and rheumatoid arthritis (RA) are the two most common, leading to considerable functional limitations and irreversible disability when patients are unsuccessfully treated. Although the specific causes of many rheumatic conditions remain unknown, it is generally accepted that immune mechanisms and/or uncontrolled inflammatory responses are involved in their etiology and symptomatology. In this regard, the bidirectional communication between neuroendocrine and immune system has been demonstrated to provide a homeostatic network that is involved in several pathological conditions. Adipokines represent a wide variety of bioactive, immune and inflammatory mediators mainly released by adipocytes that act as signal molecules in the neuroendocrine-immune interactions. Adipokines can also be synthesized by synoviocytes, osteoclasts, osteoblasts, chondrocytes and inflammatory cells in the joint microenvironment, showing potent modulatory properties on different effector cells in OA and RA pathogenesis. Effects of adiponectin, leptin, resistin and visfatin on local and systemic inflammation are broadly described. However, more recently, other adipokines, such as progranulin, chemerin, lipocalin-2, vaspin, omentin-1 and nesfatin, have been recognized to display immunomodulatory actions in rheumatic diseases. This review highlights the latest relevant findings on the role of the adipokine network in the pathophysiology of OA and RA.

High plasma resistin associates with severe acute kidney injury in Puumala hantavirus infection

Background

Puumala hantavirus (PUUV) infected patients typically suffer from acute kidney injury (AKI). Adipokines have inflammation modulating functions in acute diseases including AKI. We examined plasma levels of three adipokines (resistin, leptin, and adiponectin) in acute PUUV infection and their associations with disease severity.

Methods

This study included 79 patients hospitalized due to acute PUUV infection. Plasma resistin, leptin, adiponectin, as well as IL-6 and CRP, were measured at the acute phase, recovery phase and one year after hospitalization.

Results

Plasma resistin levels were significantly higher in the acute phase compared to the recovery phase and one year after (median resistin 28 pg/mL (11–107) vs. 17 pg/mL (7–36) vs. 14 pg/mL (7–31), p<0.001). Maximum resistin concentration correlated with maximum plasma creatinine levels (r = 0.63; p<0.001). The higher the amount of albuminuria in the urine dipstick test (0–1+, 2+ or 3+) at admission, the higher the median of maximum resistin (24.7 pg/mL, 25.4 pg/mL and 39.6 pg/mL, respectively, p = 0.002). High resistin was also an independent risk factor for severe AKI (creatinine ≥353.6μmol/L) (OR 1.08, 95% CI 1.02–1.14). Neither plasma leptin nor adiponectin level had any correlation with creatinine concentration or the amount of albuminuria.

Conclusions

Plasma resistin independently associates with the severity of AKI in acute PUUV infection. The association of resistin with the amount of albuminuria suggests that the level of plasma resistin is not only influenced by renal clearance but could have some role in the pathogenesis of AKI during PUUV infection.

Biomechanics, obesity, and osteoarthritis. The role of adipokines: When the levee breaks

Osteoarthritis is a high-incidence painful and debilitating disease characterized by progressive degeneration of articular joints, which indicates a breakdown in joint homeostasis favoring catabolic processes. Biomechanical loading, associated with inflammatory and metabolic imbalances of joint, strongly contributes to the initiation and progression of the disease. Obesity is a primary risk factor for disease onset, and mechanical factors increased the risk for disease progression. Moreover, inflammatory mediators, in particular, adipose tissue-derived cytokines (better known as adipokines) play a critical role linking obesity and osteoarthritis. The present article summarizes the knowledge about the role of adipokines in cartilage and bone function, highlighting their contribution to the imbalance of joint homeostasis and, consequently, pathogenesis of osteoarthritis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:594-604, 2018.

Serum levels of leptin, adiponectin and resistin in patients with ankylosing spondylitis: A systematic review and meta-analysis

OBJECTIVES

Various studies have researched the serum levels of leptin, adiponectin and resistin in patients with ankylosing spondylitis (AS), but the results were inconclusive. The purpose of this study was to systematically evaluate the correlations between serum levels of these adipokines and AS.

METHODS

Electronic databases were retrieved to search relevant publications. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by the random-effect model. Cochrane Q test and I² statistic were used to test heterogeneity. Subgroup analysis and meta-regression were applied to assess possible sources of heterogeneity.

RESULTS

A total of sixteen articles were included. Meta-analysis results indicated no statistical differences between AS patients and normal controls in serum leptin and adiponectin levels (leptin, SMD=0.829, 95% CI=-0.116 to 1.774, p=0.085; adiponectin, SMD=0.460, 95% CI=-0.004 to 0.924, p=0.052). However, AS patients had higher serum resistin levels than controls (SMD=1.413, 95% CI=0.294 to 2.531, p=0.013). Subgroup analyses suggested that Asian and African AS patients as well as patients aged <40years had higher serum leptin and resistin levels when compared to controls. Serum adiponectin levels were higher in AS patients compared to controls in subgroup of age ≥40, and serum resistin levels in subgroup of BMI ≥25. Measurement method was a source of heterogeneity for resistin. Publication bias was not observed and the robustness of study results was confirmed by sensitivity analysis.

CONCLUSION

Serum resistin, but not leptin or adiponectin levels may be closely associated with the development of AS.

Resistin as an inflammatory marker in patients with schizophrenia treated with clozapine

BACKGROUND

Schizophrenia is associated with excess cardiovascular comorbidity and mortality related to lifestyle factors, such as lack of physical activity, poor diet, and smoking. The prevalence of metabolic syndrome is increased among patients with schizophrenia, with the highest rates among patients on clozapine treatment. Smoking, obesity, physical inactivity, airway inflammation and obstruction, and adipose tissue and inflammatory marker activation are related in systemic inflammation. Low-grade inflammation is also associated with schizophrenia. Adipokine resistin is a biomarker involving several acute and chronic inflammatory states. However, the inflammatory role of resistin is so far inconclusive and studies in schizophrenia are scanty.

AIMS

The aim of the present study was to explore the role of serum resistin as an inflammatory marker in patients with schizophrenia on clozapine treatment.

METHODS

Associations between serum levels of resistin and some other selected cytokines/adipokines (adiponectin, leptin, adipsin, IL-6, IL-1Ra, TNF-α, hs-CRP) and metabolic markers in 190 patients with schizophrenia on clozapine treatment were studied using a cross-sectional study design.

RESULTS

Among male patients especially, smokers had higher levels of resistin than non-smokers, and among smokers resistin levels were associated with IL-1Ra and hs-CRP levels. In the whole patient group levels of resistin associated with levels of IL-1Ra, and among male patients with low HDL-cholesterol.

CONCLUSIONS

Resistin is a biomarker of systemic inflammation associated with smoking among patients with schizophrenia on clozapine treatment. Resistin might have a role as a marker of cardiovascular comorbidity.

The interplay between inflammation and metabolism in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by extensive synovitis resulting in erosions of articular cartilage and marginal bone that lead to joint destruction. The autoimmune process in RA depends on the activation of immune cells, which use intracellular kinases to respond to external stimuli such as cytokines, immune complexes, and antigens. An intricate cytokine network participates in inflammation and in perpetuation of disease by positive feedback loops promoting systemic disorder. The widespread systemic effects mediated by pro-inflammatory cytokines in RA impact on metabolism and in particular in lymphocyte metabolism. Moreover, RA pathobiology seems to share some common pathways with atherosclerosis, including endothelial dysfunction that is related to underlying chronic inflammation. The extent of the metabolic changes and the types of metabolites seen may be good markers of cytokine-mediated inflammatory processes in RA. Altered metabolic fingerprints may be useful in predicting the development of RA in patients with early arthritis as well as in the evaluation of the treatment response. Evidence supports the role of metabolomic analysis as a novel and nontargeted approach for identifying potential biomarkers and for improving the clinical and therapeutical management of patients with chronic inflammatory diseases. Here, we review the metabolic changes occurring in the pathogenesis of RA as well as the implication of the metabolic features in the treatment response.

Adipokines as potential biomarkers in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic inflammatory autoimmune disease characterized by severe joint injury. Recently, research has been focusing on the possible identification of predictor markers of disease onset and/or progression, of joint damage, and of therapeutic response. Recent findings have uncovered the role of white adipose tissue as a pleiotropic organ not only specialized in endocrine functions but also able to control multiple physiopathological processes, including inflammation. Adipokines are a family of soluble mediators secreted by white adipose tissue endowed with a wide spectrum of actions. This review will focus on the recent advances on the role of the adipokine network in the pathogenesis of RA. A particular attention will be devoted to the action of these proteins on RA effector cells, and on the possibility to use circulating levels of adipokines as potential biomarkers of disease activity and therapeutic response.

Adipokines, metabolic syndrome and rheumatic diseases

The metabolic syndrome (MetS) is a cluster of cardiometabolic disorders that result from the increasing prevalence of obesity. The major components of MetS include insulin resistance, central obesity, dyslipidemia, and hypertension. MetS identifies the central obesity with increased risk for cardiovascular diseases (CVDs) and type-2 diabetes mellitus (T2DM). Patients with rheumatic diseases, such as rheumatoid arthritis, osteoarthritis, systemic lupus erythematosus, and ankylosing spondylitis, have increased prevalence of CVDs. Moreover, CVD risk is increased when obesity is present in these patients. However, traditional cardiovascular risk factors do not completely explain the enhanced cardiovascular risk in this population. Thus, MetS and the altered secretion patterns of proinflammatory adipokines present in obesity could be the link between CVDs and rheumatic diseases. Furthermore, adipokines have been linked to the pathogenesis of MetS and its comorbidities through their effects on vascular function and inflammation. In the present paper, we review recent evidence of the role played by adipokines in the modulation of MetS in the general population, and in patients with rheumatic diseases.

Anti-inflammatory properties of a dual PPARgamma/alpha agonist muraglitazar in in vitro and in vivo models

Introduction

Peroxisome proliferator-activated receptor (PPAR) agonists are widely used drugs in the treatment of diabetes and dyslipidemia. In addition to their metabolic effects, PPAR isoforms PPARα and PPARγ are also involved in the regulation of immune responses and inflammation. In the present study, we investigated the effects of a dual PPARγ/α agonist muraglitazar on inflammatory gene expression in activated macrophages and on carrageenan-induced inflammation in the mouse.

Methods

J774 murine macrophages were activated by lipopolysaccharide (LPS) and treated with dual PPARγ/α agonist muraglitazar, PPARγ agonist GW1929 or PPARα agonist fenofibrate. The effects of PPAR agonists on cytokine production and the activation of inducible nitric oxide synthase (iNOS) pathway were investigated by ELISA, Griess method, Western blotting and quantitative RT-PCR. Nuclear translocation, DNA-binding activity and reporter gene assays were used to assess the activity of nuclear factor kappa B (NF-kB) transcription factor. Carrageenan-induced paw oedema was used as an in vivo model of acute inflammation.

Results

Muraglitazar as well as PPARγ agonist GW1929 and PPARα agonist fenofibrate inhibited LPS-induced iNOS expression and NO production in activated macrophages in a dose-dependent manner. Inhibition of iNOS expression by muraglitazar included both transcriptional and post-transcriptional components; the former being shared by GW1929 and the latter by fenofibrate. All tested PPAR agonists also inhibited IL-6 production, while TNFα production was reduced by muraglitazar and GW1929, but not by fenofibrate. Interestingly, the anti-inflammatory properties of muraglitazar were also translated in vivo. This was evidenced by the finding that muraglitazar inhibited carrageenan-induced paw inflammation in a dose-dependent manner in mice as did iNOS inhibitor L-NIL and anti-inflammatory steroid dexamethasone.

Conclusions

These results show that muraglitazar has anti-inflammatory properties both in vitro and in vivo and these effects reflect the agonistic action through both PPARα and PPARγ.

Resistin protects against 6-hydroxydopamine-induced cell death in dopaminergic-like MES23.5 cells

Resistin is originally reported as an adipose tissue-specific hormone and is thought to represent a link between obesity and insulin-resistant diabetes. Adipokines exert energy-regulation and has been reported to have neuroprotective effect like leptin, adiponectin, and ghrelin. However, the role of resistin in neuroprotective effect has not been explored. 6-hydroxydopamine (6-OHDA), one of the most investigated Parkinson's disease neurotoxins, is widely used to study mechanisms of cell death in dopaminergic neurons. In the present study, our results show that treatment of resistin protects 6-OHDA-induced cell death in dopaminergic-like MES23.5 cells. Resistin also antagonizes 6-OHDA-induced apoptotic cell death measured by fluorescence-activated cell sorter (FACS) analysis and Hochest 33342 staining. Furthermore, treatment of resistin also dramatically reduces 6-OHDA-mediated ROS production and mitochondria transmembrane potential dissipation. Moreover, expression of 6-OHDA-induced apoptotic markers, such as Bcl-2 degradation, Bax expression, PARP degradation and caspase 3 activity increase, are all attenuated by resistin treatment. Our results also show that resistin induces up-regulation of heat shock protein (Hsp) 32 (heme oxygenase-1, HO-1) and Hsc (heat shock cognate) 70. The protective effect of resistin on 6-OHDA-induced cell death is abolished by HO-1 inhibitor zinc protoporphyrin IX and HSP inhibitor KNK437. These results suggest the neuroprotective effects of resistin against 6-OHDA-induced cell death with the underlying mechanisms of inhibiting oxidative stress and apoptosis. Therefore, we suggest that resistin may provide a useful therapeutic strategy for neurodegenerative diseases such as Parkinson's disease.

Metabolic syndrome prevalence is increased in rheumatoid arthritis patients and is associated with disease activity

OBJECTIVES

To evaluate the prevalence of metabolic syndrome (MetS) in patients with rheumatoid arthritis (RA) vs. controls, and to verify possible associations of MetS with specific disease-related factors.

METHODS

The subjects were 283 RA patients and 226 healthy controls, frequency matched by age and sex. MetS was defined according to National Cholesterol Education Program (NCEP) criteria. Disease activity was evaluated with the Disease Activity Score using 28 joints (DAS28). A standardized clinical evaluation was performed and cardiovascular risk factors were assessed.

RESULTS

The criteria for MetS were met by 39.2% RA patients vs. 19.5% in the control group (p < 0.001). Increased waist circumference, elevated blood pressure (BP), and fasting glucose were more frequent in RA patients than controls (p < 0.001 for all associations). By multiple logistic regression analysis (adjusted for age, sex, and years at school), the risk of having MetS was significantly higher for RA patients than for controls [odds ratio (OR) 1.87, 95% confidence interval (CI) 1.17-3.00, p = 0.009]. The DAS28 was significantly higher in RA patients with MetS than in those without MetS (3.59 ± 1.27 vs. 3.14 ± 1.53; p = 0.01). Disease duration, the presence of rheumatoid factor, and extra-articular manifestations were similar for patients with and without MetS.

CONCLUSIONS

MetS frequency was higher in RA patients than in controls. Among RA patients, MetS was associated with disease activity. The higher prevalence of cardiovascular risk factors in RA suggests that inflammatory processes play a notable role in the development of cardiovascular disease (CVD), and indicates that tight control of systemic inflammatory activity and CVD modifiable risk factors should be recommended.