Emerging role of leptin in rheumatoid arthritis

The impact of anti-TNF-α therapy on leptin and inflammatory markers in rheumatoid arthritis patients: a case-control study

BACKGROUND AND OBJECTIVE

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by synovial inflammation, cartilage, and bone destruction. Several studies have shown that leptin plays an important role in the pathophysiology of RA disease. This study aimed to evaluate serum levels of leptin in RA patients receiving biologic drugs compared to RA patients managed by non-biologic drugs, and healthy individuals.

METHODS AND MATERIAL

In this case-control study, three groups including RA patients receiving biological drugs (remission RA patients; n = 20), RA patients receiving DMARDs (active RA patients; n = 20), and healthy controls (n = 20) were included. Serum leptin levels and inflammatory markers, including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), were measured in all participants. These measurements were subsequently compared across the three groups. Also, the correlation between leptin and inflammatory markers in each group was evaluated.

RESULTS

In this study serum leptin levels in remission RA patients, active RA patients, and healthy individuals were 14.49 ± 6.73, 16.94 ± 7.72, and 7.59 ± 5.94, respectively. Serum leptin level was significantly higher in patients with RA compared to healthy controls. No significant difference was observed in serum leptin levels between the two groups of RA patients (P < 0.001). There was a lost correlation between leptin and inflammatory markers in patients with active RA. However, a new correlation between leptin and inflammatory markers emerged in RA patients receiving biological drugs.

CONCLUSION

Our findings suggest that anti-TNF-alpha agents do not modulate serum leptin levels in RA patients. However, these agents may change a correlation between leptin and C-reactive protein (CRP) that is absent in patients with active RA.

TRIAL REGISTRATION

Not applicable in case control study.

Cardio-Rheumatology Insights Into Hypertension: Intersection of Inflammation, Arteries, and Heart

There is an increased prevalence of atherosclerotic cardiovascular disease (ASCVD) in patients with inflammatory rheumatic diseases (IRD) including rheumatoid arthritis, systemic lupus erythematosus, psoriatic arthritis, and systemic sclerosis. The mechanism for the development of ASCVD in these conditions has been linked not only to a higher prevalence and undertreatment of traditional cardiovascular (CV) risk factors but importantly to chronic inflammation and a dysregulated immune system which contribute to impaired endothelial and microvascular function, factors that may contribute to accelerated atherosclerosis. Accurate ASCVD risk stratification and optimal risk management remain challenging in this population with many barriers that include lack of validated risk calculators, the remitting and relapsing nature of underlying disease, deleterious effect of medications used to manage rheumatic diseases, multimorbidity, decreased mobility due to joint pain, and lack of clarity about who bears the responsibility of performing CV risk assessment and management (rheumatologist vs. primary care provider vs. cardiologist). Despite recent advances in this field, there remain significant gaps in knowledge regarding the best diagnostic and management approach. The evolving field of Cardio-Rheumatology focuses on optimization of cardiovascular care and research in this patient population through collaboration and coordination of care between rheumatologists, cardiologists, radiologists, and primary care providers. This review aims to provide an overview of current state of knowledge about ASCVD risk stratification in patients with IRD, contributing factors including effect of medications, and review of the current recommendations for cardiovascular risk management in patients with inflammatory disease with a focus on hypertension as a key risk factor.

Increased serum adipokines are associated with sarcopenia in non-obese women with rheumatoid arthritis

Large cohort studies have disclosed the association between obesity and rheumatoid arthritis (RA) risk. The sarcopenia prevalence in RA patients can be up to 31%. However, there is little information linking adipokines to sarcopenia in RA, so this study aimed to investigate whether adipokines were indeed involved in secondary sarcopenia in RA with a focus on non-obese females. Sixty-four female patients and 36 controls were included in this study. The serum adipokine levels (leptin and adiponectin) were determined by ELISA kits. The impacts of adipokines on muscle atrophy and potential autophagy were examined in mouse myoblasts, C2C12, upon treatment with recombinant leptin and adiponectin agonist (AdipoRan). Interestingly, serum adiponectin was significantly increased but the ratio of leptin/adiponectin was dramatically decreased in the RA patients with sarcopenia. After normalization by body mass, serum leptin was positively associated but adiponectin was negatively associated with muscle mass respectively, even after adjustment for fat mass. Treating C2C12 cells with leptin and AdipoRan inhibited proliferation of mature myotube respectively, as did treatment with the serum from RA patients. A combination of low leptin and high AdipoRan greatly decreased myogenin, but instead increased MAFbx and MuRF-1 as well as increased Beclin 1, Atg5, and LC3β. Taken together, our study reveals that secondary sarcopenia of RA females may be an imbalance of RA-related, but not obesity-related, increase in adipokine production; additionally, the reduced leptin/adiponectin ratio could be a better indicator in monitoring sarcopenia in non-obese RA females. Moreover, adipokine imbalance may promote muscle atrophy through inducing autophagy.

Atherothrombotic Risk Factors in Patients With Rheumatoid Arthritis

BACKGROUND

The onset of cardiovascular complications has increased the mortality rate in rheumatoid arthritis (RA) patients. Presently, there is a need to diagnose cardiovascular co-morbidity in rheumatic disease. While biomarkers such as P-selectin glycoprotein ligand-1 (PSGL-1), fibrinogen, anti-thrombin III (AT-III), hsCRP, lipoprotein (a) (lp(a)), leptin, adiponectin, and asymmetric dimethyl arginine (ADMA) are already established as independent risk factors for the development of atherosclerosis, the association of these biomarkers with disease activity in RA patients is unclear.

METHODS

The case-control study comprised 40 cases along with age- and gender-matched controls recruited from a tertiary care hospital in southern India. Platelet activation in plasma was analyzed by flow cytometry using CD41 per CPCY 5.5 (platelet marker) and human CD62P FITC monoclonal antibody (P-selectin marker). Other parameters were quantified through nephelometry and ELISA. The association between the risk factors and RA disease severity, as per the disease activity score (DAS/DAS28), was analyzed. Furthermore, an ROC analysis was done to assess the utility of these biomarkers in the diagnosis of RA.

RESULTS

With the exception of leptin, adiponectin, and ADMA, there was a significant increase in the levels of PSGL-1, fibrinogen, AT-III, hsCRP, and lp(a) when compared to healthy controls. Conventional risk factors contributing to dyslipidemia were also assessed, in which the low-density lipoprotein (LDL)/high-density lipoprotein (HDL) ratio was found to be significantly higher in RA patients compared to controls. Moreover, a significant positive correlation was identified between DAS score and activated platelets, fibrinogen, and hsCRP. ROC analysis identified that fibrinogen could predict the RA disease status with 95% accuracy, followed by activated platelets and hsCRP.

CONCLUSION

Several of the studied atherothrombotic risk factors were significantly altered in patients with RA. Activated platelets, fibrinogen, and hsCRP were associated with disease activity and also served as good diagnostic predictors for RA. Based on our findings, further studies could explore the potential of introducing anti-thrombotic agents in the treatment regimen of patients with RA.

Obesity and recurrent miscarriage: The interconnections between adipose tissue and the immune system

Currently, obesity is considered a global public health problem. It is the main risk factor for noncommunicable diseases and reproductive complications, such as recurrent miscarriage (RM). RM affects approximately 1% of couples of reproductive age, and recent studies suggest that its prevalence is increasing. Immunological abnormalities may be responsible for a significant number of cases of unexplained RM. Obesity is recognized as a chronic low-grade inflammatory condition. The accumulation of fat in obese adipose tissue promotes changes in the local and systemic immune response. Adipokines, exosomes, micro-RNAs, lipids, and other factors released or secreted by adipose tissue are responsible for the interconnection between obesity and the immune system. Obesity-induced dysregulation of the innate and acquired immune response is also involved in the immunopathology of pregnancy loss in patients with unexplained RM. Therefore, understanding the communication pathways between maternal adipose tissue and the immune response in women living with obesity and RM is an important objective. Thus, diagnostic tools and new immunomodulatory therapies may be proposed for the management of patients with concurrent obesity and RM.

Time restricted feeding modifies leukocyte responsiveness and improves inflammation outcome

Time restricted eating, the dietary approach limiting food intake to a maximal 10-hour period of daytime is considered beneficial in metabolic dysfunctions, such as obesity and diabetes. Rhythm of food intake and parallel changes in serum nutrient levels are also important entrainment signals for the circadian clock, particularly in tissues involved in metabolic regulation. As both the metabolic state and the circadian clock have large impact on immune functions, we investigated in mice whether time restricted feeding (TRF) affects systemic inflammatory potential. TRF slackened the symptoms in K/BxN serum-transfer arthritis, an experimental model of human autoimmune joint inflammation. Compared to ad libitum conditions TRF reduced the expression of inflammatory mediators in visceral adipose tissue, an integrator and coordinator of metabolic and inflammatory processes. Furthermore, TRF strengthened the oscillation of peripheral leukocyte counts and alongside decreased the pool of both marginated and tissue leukocytes. Our data suggest that the altered leukocyte distribution in TRF mice is related to the attenuated expression of adhesion molecules on the surface of neutrophils and monocytes. We propose that TRF modifies both rhythm and inflammatory potential of leukocytes which contribute to the milder reactivity of the immune system and therefore time-restricted eating could serve as an effective complementary tool in the therapy of autoinflammatory processes.

Adiponectin and Leptin as Biomarkers of Disease Activity and Metabolic Disorders in Rheumatoid Arthritis Patients

Background

Rheumatoid arthritis (RA) is an autoimmune disease, characterized by inflammation of multiple joints, resulting in irreversible cartilage and bone destruction. Chronic disease activity may be associated with metabolic disorders and premature atherosclerosis. Adipokines are involved not only in metabolism regulation, but also in inflammatory and immune response.

Aim

This study is designed to explore relationships between adipokines (adiponectin, leptin) and metabolic parameters, as well as disease activity, in patients with chronic RA.

Methods

This cross-sectional study enrolled 109 patients with RA. The clinical assessment was performed including tender and swollen joint counts, Disease Activity Score 28 (DAS28), body mass index (BMI). The following laboratory parameters were performed: erythrocyte sedimentation rate, C-reactive protein, glucose, lipid profile, creatinine. Serum levels of adiponectin and leptin were assessed by enzyme-linked immunosorbent assay (ELISA).

Results

The mean adiponectin and leptin serum concentrations remained within normal ranges. Both, adiponectin and leptin levels were not associated with current disease activity markers (clinical and laboratory), and type of treatment. Significant relationships were found between adipokines and metabolic parameters, as well as with coexistent conditions and RA characteristics. Higher leptin levels were noticed in patients with hypertension. In the multiple linear regression analysis, correlations were confirmed. Adiponectin was positively correlated with HDL-C (b = 0.37, p < 0.001), age (b = 0.39, p< 0.001), and negatively with glucose (b = -0.17, p = 0.03). Leptin was positively correlated with BMI (b = 0.58, p < 0.001), and negatively with estimated glomerular filtration rate (eGFR) (b = -0.30, p < 0.001).

Conclusion

The results of this study show the value of adipokines as indicators of metabolic disorders, rather than inflammatory markers in patients with chronic RA, treated with immunosuppressive or biological drugs. High leptin level may indicate poor prognostic factors, kidney and cardiovascular complications. Adiponectin seems to be protective against metabolic disorders in chronic RA.

Organokines in Rheumatoid Arthritis: A Critical Review

Rheumatoid arthritis (RA) is a systemic autoimmune disease that primarily affects the joints. Organokines can produce beneficial or harmful effects in this condition. Among RA patients, organokines have been associated with increased inflammation and cartilage degradation due to augmented cytokines and metalloproteinases production, respectively. This study aimed to perform a review to investigate the role of adipokines, osteokines, myokines, and hepatokines on RA progression. PubMed, Embase, Google Scholar, and Cochrane were searched, and 18 studies were selected, comprising more than 17,000 RA patients. Changes in the pattern of organokines secretion were identified, and these could directly or indirectly contribute to aggravating RA, promoting articular alterations, and predicting the disease activity. In addition, organokines have been implicated in higher radiographic damage, immune dysregulation, and angiogenesis. These can also act as RA potent regulators of cells proliferation, differentiation, and apoptosis, controlling osteoclasts, chondrocytes, and fibroblasts as well as immune cells chemotaxis to RA sites. Although much is already known, much more is still unknown, principally about the roles of organokines in the occurrence of RA extra-articular manifestations.

Leptin in Osteoarthritis and Rheumatoid Arthritis: Player or Bystander?

White adipose tissue (WAT) is a specialized tissue whose main function is lipid synthesis and triglyceride storage. It is now considered as an active organ secreting a plethora of hormones and cytokines namely adipokines. Discovered in 1994, leptin has emerged as a key molecule with pleiotropic functions. It is primarily recognized for its role in regulating energy homeostasis and food intake. Currently, further evidence suggests its potent role in reproduction, glucose metabolism, hematopoiesis, and interaction with the immune system. It is implicated in both innate and adaptive immunity, and it is reported to contribute, with other adipokines, in the cross-talking networks involved in the pathogenesis of chronic inflammation and immune-related diseases of the musculo-skeletal system such as osteoarthritis (OA) and rheumatoid arthritis (RA). In this review, we summarize the most recent findings concerning the involvement of leptin in immunity and inflammatory responses in OA and RA.

Metabolic syndrome and hidradenitis suppurativa: epidemiological, molecular, and therapeutic aspects

Hidradenitis suppurativa (HS) is a chronic, suppurative condition of the pilosebaceous unit. Patients suffering from HS demonstrate a molecular profile in keeping with a state of systemic inflammation and are often found to fit the criteria for a diagnosis of metabolic syndrome (MetS). In this paper, we review the literature with regards to established data on the prevalence of MetS in HS patients and revise the odds ratio of comorbid disease. Furthermore, we attempt to draw parallels between inflammatory pathways in HS and MetS and evaluate how convergences may explain the risk of comorbid disease, necessitating the need for multidisciplinary care.

Leptin, Both Bad and Good Actor in Cancer

Leptin is an important regulator of basal metabolism and food intake, with a pivotal role in obesity. Leptin exerts many different actions on various tissues and systems, including cancer, and is considered as a linkage between metabolism and the immune system. During the last decades, obesity and leptin have been associated with the initiation, proliferation and progression of many types of cancer. Obesity is also linked with complications and mortality, irrespective of the therapy used, affecting clinical outcomes. However, some evidence has suggested its beneficial role, called the "obesity paradox", and the possible antitumoral role of leptin. Recent data regarding the immunotherapy of cancer have revealed that overweight leads to a more effective response and leptin may probably be involved in this beneficial process. Since leptin is a positive modulator of both the innate and the adaptive immune system, it may contribute to the increased immune response stimulated by immunotherapy in cancer patients and may be proposed as a good actor in cancer. Our purpose is to review this dual role of leptin in cancer, as well as trying to clarify the future perspectives of this adipokine, which further highlights its importance as a cornerstone of the immunometabolism in oncology.

Association of Leptin Gene Polymorphisms with Rheumatoid Arthritis in a Chinese Population

Background

Recently, increasing studies have revealed that leptin is involved in the development of rheumatoid arthritis (RA). This study is aimed at exploring the association of leptin gene single nucleotide polymorphisms (SNPs) with susceptibility to RA in a Chinese population.

Methods

We recruited 600 RA patients and 600 healthy controls from a Chinese population and analyzed their three leptin SNPs (rs10244329, rs2071045, and rs2167270) using the improved Multiplex Ligase Detection Reaction (iMLDR) assays. The associations of these SNPs with clinical manifestations of RA were also analyzed. Enzyme-linked immunosorbent assay (ELISA) was performed for plasma leptin determination.

Results

No significant difference in either allele or genotype frequencies of these three SNPs between RA patients and healthy controls was observed (all P > 0.05). Association between the genotype effects of dominant, recessive models was also not found (all P > 0.05). No significant difference in plasma leptin levels was detected between RA patients and controls (P > 0.05).

Conclusion

Leptin gene (rs10244329, rs2071045, and rs2167270) polymorphisms are not associated with RA genetic susceptibility and its clinical features in the Chinese population.

The association between increased body mass index and response to conventional synthetic DMARD treatment in rheumatoid arthritis: Results from the METEOR database

BACKGROUND

Few data exist on the association between increased BMI and response to conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) in rheumatoid arthritis (RA).We aimed to explore the association between increased (overweight or obese) BMI on csDMARD-prescribing, methotrexate-dose and disease activity over 12-months.

METHODS

Participants in an international RA database were stratified into early (<1year post-diagnosis) and established RA. EULAR response, DAS28 remission and treatments were recorded at baseline, 6-months and 12-months. Increased BMI was explored in early and established RA, as predictors of good EULAR response, DAS28 remission, number of csDMARDs and methotrexate-dose, using logistic and linear regression.

RESULTS

Data from 1313 patients, 44.3% with early RA, were examined. In early RA, increased BMI was not significantly associated with remission. In established RA, obese patients on monotherapy were significantly less likely to achieve good EULAR response or DAS28 remission at 6 months and more likely to be treated with combination csDMARDs, compared with normal BMI. In patients taking methotrexate, overweight and obese patients with early and established RA were exposed to higher methotrexate doses (mono- and combination-therapy), with a mean dose of 20mg/week, compared to 15mg/week in those of normal BMI.

CONCLUSION

We observed, compared to patients with normal BMI, overweight and obese individuals experienced more intensive csDMARD exposures. Similar response rates were observed in early RA but increased BMI was associated with reduced response in established RA. Optimisation of targeted RA treatment remains important, particularly in those with increased BMI where response in established disease may be attenuated.

The complex role of adipokines in obesity, inflammation, and autoimmunity

The global obesity epidemic is a major contributor to chronic disease and disability in the world today. Since the discovery of leptin in 1994, a multitude of studies have characterized the pathological changes that occur within adipose tissue in the obese state. One significant change is the dysregulation of adipokine production. Adipokines are an indispensable link between metabolism and optimal immune system function; however, their dysregulation in obesity contributes to chronic low-grade inflammation and disease pathology. Herein, I will highlight current knowledge on adipokine structure and physiological function, and focus on the known roles of these factors in the modulation of the immune response. I will also discuss adipokines in rheumatic and autoimmune diseases.

Association of Leptin Levels and Disease Activity in Patients with Early Rheumatoid Arthritis

OBJECTIVE

Previous studies have reported a link between metabolic parameters and disease activity in rheumatoid arthritis (RA), although the evidence is limited in early RA. We aimed to investigate the relationship between disease activity and adipocytokine levels in subjects with early RA.

METHODS

Forty-seven patients with early RA (symptom duration ≤12 months) were enrolled. Disease activity was determined by DAS28-CRP. Patients were treated with DMARDs according to the EULAR recommendations. Subjects were tested before and five months after treatment.

RESULTS

Early RA patients with high disease activity (DAS28-CRP > 4.9) had greater BMI (31.2 ± 6.8 kg/m² vs. 26.7 ± 4.1 kg/m²; p = 0.006) and higher leptin levels (14.62 ± 15.60 ng/mL vs. 7.82 ± 8.00 ng/mL; p = 0.048). Levels of other adipocytokines were not significantly different. Leptin levels were similar in subjects with mild/moderate disease activity and controls. DAS28-CRP was correlated with leptin (r = 0.303, p = 0.039). Leptin levels decreased significantly after treatment (from 10.86 ± 12.34 ng/mL to 9.22 ± 9.29 ng/mL; p = 0.047) along with insulin levels (from 13.68 ± 21.90 mU/L to 7.09 ± 4.72 mU/L; p = 0.010) and HOMA-IR (from 4.39 ± 9.53 to 1.70 ± 1.38; p = 0.012). HDL cholesterol levels increased (from 41 ± 10 mg/dL48 ± 10 mg/dL; p <0.001).

CONCLUSION

Leptin levels were associated with disease activity in patients with early RA and these levels decreased after treatment with DMARDs. Further research is needed to elicit leptin's role to regulate disease activity in early RA.

Effect of Leptin on Chronic Inflammatory Disorders: Insights to Therapeutic Target to Prevent Further Cardiovascular Complication

In response to obesity-associated chronic inflammatory disorders, adipose tissue releases a biologically active peptide known as leptin. Leptin activates the secretion of chemical mediators, which contribute to the pathogenesis of chronic inflammatory disorders, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and psoriasis. Conversely, adiposity and obesity are the major aggravating risk factors in the pathogenesis of metabolic syndrome (MetS), including type II diabetes mellitus and obesity-associated hypertension. Elevated level of leptin in obesity-associated hypertension causes an increase in the production of aldosterone, which also results in elevation of arterial blood pressure. Hyperleptinemia is associated with the progress of the atherosclerosis through secretion of pro-inflammatory cytokines, like interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), IL-17, and other cytokines to promote inflammation. The release of those cytokines leads to chronic inflammatory disorders and obesity-associated MetS. Thus, the aberrant leptin level in both MetS and chronic inflammatory disorders also leads to the complication of cardiovascular diseases (CVD). Therapeutic target of leptin regarding its pro-inflammatory effect and dysregulated sympathetic nervous system activity may prevent further cardiovascular complication. This review mainly assesses the mechanism of leptin on the pathogenesis and further cardiovascular risk complication of chronic inflammatory disorders.

Obesity-Related Traits and the Development of Rheumatoid Arthritis: Evidence From Genetic Data

Objective

To investigate the association between obesity‐related traits and risk of rheumatoid arthritis (RA).

Methods

We conducted genetic correlation analysis and a 2‐sample Mendelian randomization (MR) study, using genome‐wide genetic data based on >850,000 individuals of European ancestry. Summary statistics were collected from the largest genome‐wide association study conducted to date for body mass index (BMI; n = 806,810), waist‐to‐hip ratio (WHR; n = 697,734), WHR adjusted for BMI (WHRadjBMI; n = 694,649), and RA (n_case = 14,361, n_control = 43,923). We conducted cross‐trait linkage disequilibrium score regression and ρ‐HESS analyses to quantify genetic correlation between pairs of traits (causal overlap). For each obesity‐related exposure, we utilized independent, genome‐wide significant single‐nucleotide polymorphisms (P < 5 × 10⁻⁹) as instruments to perform MR analysis (causal relationship). We interrogated the causal relationship both in the general population and in a sex‐specific manner and calculated odds ratios (ORs) and 95% confidence intervals (95% CIs). Sensitivity analyses were performed to validate MR model assumptions.

Results

Despite a negligible overall genetic correlation between the 3 obesity‐related traits and RA, we found significant local genetic correlations at several regions on chromosome 6 (positions 28–29M, 30–35M, and 50–52M), highlighting a shared genetic basis. We further observed an increased risk of RA per SD increment (4.8 kg/m²) in genetically predicted BMI (OR 1.22 [95% CI 1.09–1.37]). The effect was consistent across sensitivity analyses and comparable between sexes (OR 1.22 [95% CI 1.04–1.44] in male subjects and 1.19 [95% CI 1.04–1.36] in female subjects). However, we did not find evidence supporting a causal role of either WHR (OR 0.98 [95% CI 0.84–1.14]) or WHRadjBMI (OR 0.90 [95% CI 0.79–1.04]) in RA.

Conclusion

Genetically predicted BMI significantly increases RA risk. Future studies are needed to understand the biologic mechanisms underlying this link.

Adipokines: New Potential Therapeutic Target for Obesity and Metabolic, Rheumatic, and Cardiovascular Diseases

Besides its role as an energy storage organ, adipose tissue can be viewed as a dynamic and complex endocrine organ, which produces and secretes several adipokines, including hormones, cytokines, extracellular matrix (ECM) proteins, and growth and vasoactive factors. A wide body of evidence showed that adipokines play a critical role in various biological and physiological functions, among which feeding modulation, inflammatory and immune function, glucose and lipid metabolism, and blood pressure control. The aim of this review is to summarize the effects of several adipokines, including leptin, diponectin, resistin, chemerin, lipocalin-2 (LCN2), vaspin, omentin, follistatin-like 1 (FSTL1), secreted protein acidic and rich in cysteine (SPARC), secreted frizzled-related protein 5 (SFRP5), C1q/TNF-related proteins (CTRPs), family with sequence similarity to 19 member A5 (FAM19A5), wingless-type inducible signaling pathway protein-1 (WISP1), progranulin (PGRN), nesfatin-1 (nesfatin), visfatin/PBEF/NAMPT, apelin, retinol binding protein 4 (RPB4), and plasminogen activator inhibitor-1 (PAI-1) in the regulation of insulin resistance and vascular function, as well as many aspects of inflammation and immunity and their potential role in managing obesity-associated diseases, including metabolic, osteoarticular, and cardiovascular diseases.

Re-evaluation of serum leptin and adiponectin concentrations normalized by body fat mass in patients with rheumatoid arthritis

Leptin and adiponectin are produced mainly in adipocytes and classified as adipocytokines because of their possible involvement in inflammation and immunity. The aim of this study was to elucidate the relationships of these adipocytokines with the disease activities of RA. We examined leptin and adiponectin concentrations and inflammatory markers such as metalloproteinase-3 (MMP-3) in 136 patients with rheumatoid arthritis (RA) (26 males and 110 females, 69.6 ± 9.3 years) and 78 controls (36 males and 42 females, 66.7 ± 15.0 years). Serum leptin and adiponectin concentrations correlated positively (r = 0.565, P < 0.001) and negatively (r = –0.331, P < 0.001) to the amount of body fat, respectively. Serum leptin and adiponectin concentrations normalized by body fat mass were significantly higher in RA than those in controls [leptin, 1.24 (median) ng/mL/kg fat in RA vs. 0.76 ng/mL/kg fat in controls; adiponectin, 0.74 μg/mL/kg fat in RA vs. 0.44 μg/mL/kg fat in controls]. Normalized adiponectin concentrations correlated positively not only to the degree of bone destruction in Steinbrocker classification but also to serum MMP-3 concentrations. Normalized leptin concentrations did not correlate to the degree of bone destruction. We conclude that adiponectin but not leptin may be involved in joint damage in RA.

Metabolic Checkpoints in Rheumatoid Arthritis

Several studies have highlighted the interplay between metabolism, immunity and inflammation. Both tissue resident and infiltrating immune cells play a major role in the inflammatory process of rheumatoid arthritis (RA) via the production of cytokines, adipo-cytokines and metabolic intermediates. These functions are metabolically demanding and require the most efficient use of bioenergetic pathways. The synovial membrane is the primary site of inflammation in RA and exhibits distinctive histological patterns characterized by different metabolism, prognosis and response to treatment. In the RA synovium, the high energy demand by stromal and infiltrating immune cells, causes the accumulation of metabolites, and adipo-cytokines, which carry out signaling functions, as well as activating transcription factors which act as metabolic sensors. These events drive immune and joint-resident cells to acquire pro-inflammatory effector functions which in turn perpetuate chronic inflammation. Whether metabolic changes are a consequence of the disease or one of the causes of RA pathogenesis is still under investigation. This review covers our current knowledge of cell metabolism in RA. Understanding the intricate interactions between metabolic pathways and the inflammatory and immune responses will provide more awareness of the mechanisms underlying RA pathogenesis and will identify novel therapeutic options to treat this disease.

Association of Circulating COMP and YKL-40 as Markers of Metabolic Changes of Cartilage with Adipocytokines in Juvenile Idiopathic Arthritis

The aim of this study was to evaluate the association of circulating cartilage oligomeric matrix protein (COMP) and human cartilage glycoprotein-39 (YKL-40) as markers of metabolic changes of cartilage, with leptin, adiponectin, and resistin in juvenile idiopathic arthritis (JIA) patients before and after treatment. A significant decrease of COMP and an increase of YKL-4 were found in blood of untreated patients. JIA treatment leading to clinical improvement resulted in normalization of COMP levels only. Concentrations of both markers in treated patients, while showing no clinical improvement, differed from those in controls and patients with remission. The leptin level decreased (p < 0.05) in untreated patients; however, concentrations of adiponectin and resistin increased (p < 0.05) as compared to controls. JIA treatment resulted in normalization of adipocytokine levels in remissive patients but not those with active JIA. Untreated patients showed a correlation between COMP and leptin, adiponectin, and body mass index (BMI) and between YKL-40 and leptin, adiponectin, BMI, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). In inactive JIA, a correlation between YKL-40 and leptin was shown. Treated patients with an active JIA demonstrated a correlation between COMP and adiponectin and between YKL-40 and leptin, adiponectin, BMI, CRP, and ESR. The results of this work indicate that leptin and adiponectin but not resistin may be involved in the development and progression of joint dysfunction in JIA. Additionally, we suggest that YKL-40 may be a useful biomarker of disease activity and may be used to assess treatment towards remission, as compared to COMP.

The Systemic Immune Response to Collagen-Induced Arthritis and the Impact of Bone Injury in Inflammatory Conditions

Rheumatoid arthritis (RA) is a systemic disease that affects the osteoarticular system, associated with bone fragility and increased risk of fractures. Herein, we aimed to characterize the systemic impact of the rat collagen-induced arthritis (CIA) model and explore its combination with femoral bone defect (FD). The impact of CIA on endogenous mesenchymal stem/stromal cells (MSC) was also investigated. CIA induction led to enlarged, more proliferative, spleen and draining lymph nodes, with altered proportion of lymphoid populations. Upon FD, CIA animals increased the systemic myeloid cell proportions, and their expression of co-stimulatory molecules CD40 and CD86. Screening plasma cytokine/chemokine levels showed increased tumor necrosis factor-α (TNF-α), Interleukin (IL)-17, IL-4, IL-5, and IL-12 in CIA, and IL-2 and IL-6 increased in CIA and CIA+FD, while Fractalkine and Leptin were decreased in both groups. CIA-derived MSC showed lower metabolic activity and proliferation, and significantly increased osteogenic and chondrogenic differentiation markers. Exposure of control-MSC to TNF-α partially mimicked the CIA-MSC phenotype in vitro. In conclusion, inflammatory conditions of CIA led to alterations in systemic immune cell proportions, circulating mediators, and in endogenous MSC. CIA animals respond to FD, and the combined model can be used to study the mechanisms of bone repair in inflammatory conditions.

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.

Clinical associations of serum leptin and leptin/adiponectin ratio in systemic sclerosis

INTRODUCTION

Leptin and adiponectin have recently received the attention of researchers as attractive biomarkers in systemic sclerosis (SSc) because of their role in the inflammatory process, vascular function and fibrosis. We hypothesized that leptin and adiponectin may be associated with disease activity and severity in patients with SSc.

AIM

To compare serum leptin, adiponectin and leptin/adiponectin levels in patients with SSc and healthy controls and to evaluate their possible relationship with frequently used laboratory markers and clinical findings.

MATERIAL AND METHODS

The study included 48 Caucasian female patients with SSc and 38 healthy controls. Serum concentrations of leptin and adiponectin were measured in patients and controls using commercially available ELISA Kits (Quantikine ELISA Kit R&D Systems, Minneapolis, MN, USA). The results were assessed by the Mann-Whitney U-test and Spearman's correlation test.

RESULTS

Leptin and adiponectin levels correlated with body mas index in SSc patients (r = 0.495, p = 0.000398 and r = -0.306; p = 0.0342) in contrast to healthy controls (p = 0.070 and p = 0.256, respectively), and, in SSc patients only, a strong negative correlation was observed between leptin and adiponectin serum levels (r = -0.314; p = 0.0312). Diffuse form of the disease (dcSSc) was associated with significantly lower serum adiponectin levels (8638.62 ±10382.62). Active disease was associated with significantly lower leptin concentration (13700.49 ±18293.32) and there was a significant negative correlation between leptin serum level and activity index score (r = -0.342; p = 0.0185).

CONCLUSIONS

The results of our study indicate that leptin levels might correlate with disease activity and subtype in SSc patients.

Hidradenitis suppurativa and metabolic syndrome - systematic review and adjusted meta-analysis

BACKGROUND

Hidradenitis suppurativa (HS) is a debilitating and distressing chronic systemic inflammatory skin disease. There have been several prior observational studies which reported a possibility link between HS and metabolic syndrome, however the current evidence is not definitive. It is unclear in HS whether this possible relationship is independent or driven by underlying risk factors and comorbidities.

OBJECTIVE

To determine whether HS is independently associated with metabolic syndrome via adjusted meta-analysis of case-control studies.

METHODS

A systematic review and meta-analysis was performed according to PRISMA guidelines. Electronic searches were performed using six electronic databases (Ovid Medline, PubMed, CCTR, CDSR, ACP Journal Club, and DARE) from their inception until September 2018. Data were extracted and analyzed according to predefined clinical endpoints.

RESULTS

We identified six case-control studies included for meta-analysis. Based on unadjusted analysis, we found a significant association between adult cases of HS and metabolic syndrome (OR 1.95, 95% CI 1.31-2.89, P = 0.001). Adjusted meta-analysis, after adjustment for age, sex, other cardiovascular risk factors, and comorbidities, found a significant association (OR 2.19, 95% CI 1.70-2.81, I²  = 32%, P < 0.00001).

LIMITATIONS

Studies reviewed were observational by design which are susceptible to bias, and there was lack of randomization. The quality of the current systematic review is also limited by the quality of available evidence which was predominantly observational in nature.

CONCLUSIONS

This pooled analysis of existing case-control studies supports an association between HS and metabolic syndrome. Clinicians treating patients with HS should be aware of this potential association.

Autoimmune Disease-Associated Hypertension

Purpose of Review

To highlight important new findings on the topic of autoimmune disease-associated hypertension.

Recent Findings

Autoimmune diseases including systemic lupus erythematosus and rheumatoid arthritis are associated with an increased risk for hypertension and cardiovascular disease. A complex interaction among genetic, environmental, hormonal, and metabolic factors contribute to autoimmune disease susceptibility while promoting chronic inflammation that can lead to alterations in blood pressure. Recent studies emphasize an important mechanistic role for autoantibodies in autoimmune disease-associated hypertension. Moving forward, understanding how sex hormones, neutrophils, and mitochondrial dysfunction contribute to hypertension in autoimmune disease will be important.

Summary

This review examines the prevalent hypertension in autoimmune disease with a focus on the impact of immune system dysfunction on vascular dysfunction and renal hemodynamics as primary mediators with oxidative stress as a main contributor.

KCa1.1 and Kv1.3 channels regulate the interactions between fibroblast-like synoviocytes and T lymphocytes during rheumatoid arthritis

BACKGROUND

Fibroblast-like synoviocytes (FLS) and CCR7- effector memory T (TEM) cells are two of the major cell types implicated in the progression of rheumatoid arthritis (RA). In particular, FLS become highly invasive, whereas TEM cells proliferate and secrete proinflammatory cytokines, during RA. FLS and T cells may also interact and influence each other's phenotypes. Inhibition of the pathogenic phenotypes of both FLS and TEM cells can be accomplished by selectively blocking the predominant potassium channels that they upregulate during RA: KCa1.1 (BK, Slo1, MaxiK, KCNMA1) upregulated by FLS and Kv1.3 (KCNA3) upregulated by activated TEM cells. In this study, we investigated the roles of KCa1.1 and Kv1.3 in regulating the interactions between FLS and TEM cells and determined if combination therapies of KCa1.1- and Kv1.3-selective blockers are more efficacious than monotherapies in ameliorating disease in rat models of RA.

METHODS

We used in vitro functional assays to assess the effects of selective KCa1.1 and Kv1.3 channel inhibitors on the interactions of FLS isolated from rats with collagen-induced arthritis (CIA) with syngeneic TEM cells. We also used flow cytometric analyses to determine the effects of KCa1.1 blockers on the expression of proteins used for antigen presentation on CIA-FLS. Finally, we used the CIA and pristane-induced arthritis models to determine the efficacy of combinatorial therapies of KCa1.1 and Kv1.3 blockers in reducing disease severity compared with monotherapies.

RESULTS

We show that the interactions of FLS from rats with CIA and of rat TEM cells are regulated by KCa1.1 and Kv1.3. Inhibiting KCa1.1 on FLS reduces the ability of FLS to stimulate TEM cell proliferation and migration, and inhibiting Kv1.3 on TEM cells reduces TEM cells' ability to enhance FLS expression of KCa1.1 and major histocompatibility complex class II protein, as well as stimulates their invasion. Furthermore, we show that combination therapies of selective KCa1.1 and Kv1.3 blockers are more efficacious than monotherapies at reducing signs of disease in two rat models of RA.

CONCLUSIONS

Our results demonstrate the importance of KCa1.1 and Kv1.3 in regulating FLS and TEM cells during RA, as well as the value of combined therapies targeting both of these cell types to treat RA.

Adipocytokines in Rheumatoid Arthritis: The Hidden Link between Inflammation and Cardiometabolic Comorbidities

Rheumatoid arthritis is a chronic autoimmune disease affecting typically synovial joints and leading to progressive articular damage, disability, and reduced quality of life. Despite better recent therapeutic strategies improving long-term outcomes, RA is associated with a high rate of comorbidities, infections, malignancies, and cardiovascular disease (CVD). Remarkably, some well-known pathogenic proinflammatory mediators in RA, such as interleukin-1β (IL-1β) and tumor necrosis factor (TNF), may play a pivotal role in the development of CVD. Interestingly, different preclinical and clinical studies have suggested that biologic agents commonly used to treat RA patients may be effective in improving CVD. In this context, the contribution of adipocytokines has been suggested. Adipocytokines are pleiotropic molecules, mainly released by white adipose tissue and immune cells. Adipocytokines modulate the function of different tissues and cells, and in addition to energy homeostasis and metabolism, amplify inflammation, immune response, and tissue damage. Adipocytokines may contribute to the proinflammatory state in RA patients and development of bone damage. Furthermore, they could be associated with the occurrence of CVD. In this study, we reviewed available evidence about adipocytokines in RA, because of their involvement in disease activity, associated CVD, and possible biomarkers of prognosis and treatment outcome and because of their potential as a possible new therapeutic target.

Visfatin alters the cytokine and matrix-degrading enzyme profile during osteogenic and adipogenic MSC differentiation

OBJECTIVES

Age-related bone loss is associated with bone marrow adiposity. Adipokines (e.g., visfatin, resistin, leptin) are adipocyte-derived factors with immunomodulatory properties and might influence differentiation of bone marrow-derived mesenchymal stem cells (MSC) in osteoarthritis (OA) and osteoporosis (OP). Thus, the presence of adipokines and MMPs in bone marrow and their effects on MSC differentiation were analyzed.

METHODS

MSC and ribonucleic acid (RNA) were isolated from femoral heads after hip replacement surgery of OA or osteoporotic femoral neck fracture (FF) patients. Bone structural parameters were evaluated by microcomputed tomography (μCT). MSC were differentiated towards adipocytes or osteoblasts with/without adipokines. Gene expression (adipokines, bone marker genes, MMPs, TIMPs) and cytokine production was evaluated by realtime-polymerase chain reaction (realtime-PCR) and enzyme-linked immunosorbent assay (ELISA). Matrix mineralization was quantified using Alizarin red S staining.

RESULTS

μCT showed an osteoporotic phenotype of FF compared to OA bone (reduced trabecular thickness and increased ratio of bone surface vs volume of solid bone). Visfatin and leptin were increased in FF vs OA. Visfatin induced the secretion of IL-6, IL-8, and MCP-1 during osteogenic and adipogenic differentiation. In contrast to resistin and leptin, visfatin increased MMP2 and MMP13 during adipogenesis. In osteogenically differentiated cells, MMPs and TIMPs were reduced by visfatin. Visfatin significantly increased matrix mineralization during osteogenesis, whereas collagen type I expression was reduced.

CONCLUSION

Visfatin-mediated increase of matrix mineralization and reduced collagen type I expression could contribute to bone fragility. Visfatin is involved in impaired bone remodeling at the adipose tissue/bone interface through induction of proinflammatory factors and dysregulated MMP/TIMP balance during MSC differentiation.

Leptin is associated with disease activity but not with anthropometric indices in rheumatoid arthritis patients

INTRODUCTION

Leptin is a cytokine-like hormone which has a complex role in inflammation. However, the importance of leptin in the pathogenesis of rheumatoid arthritis (RA) is far from being fully elucidated. The aim of the study was to determine serum leptin levels in RA patients and to evaluate whether there is an association between disease activity, anthropometric indices and leptin levels.

MATERIAL AND METHODS

This hypothesis-generating study included 55 RA patients and 25 matched healthy subjects. The serum leptin concentration was determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Median serum leptin level in RA patients of 27.4 ng/ml (14.5-54.9 ng/ml) was statistically significantly higher (p = 0.03) compared with the median leptin value of 16.3 ng/ml (9.6-38.8 ng/ml) determined in healthy controls. The serum leptin level in the high disease activity group was significantly higher (p < 0.0005) than that in the low disease activity group and in healthy controls. A significant difference (p = 0.001) in serum leptin level was also found when the high disease activity group was compared with the moderate disease activity group. In the RA group a statistically significant positive correlation (rho = 0.390; p = 0.003) was observed between serum leptin level and disease activity score (DAS28).

CONCLUSIONS

The present results show that serum leptin levels are increased and significantly associated with disease activity in patients with RA and may have a valuable role in the inflammatory reactions and pathogenesis of RA.

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.

Obesity, Fat Mass and Immune System: Role for Leptin

Obesity is an epidemic disease characterized by chronic low-grade inflammation associated with a dysfunctional fat mass. Adipose tissue is now considered an extremely active endocrine organ that secretes cytokine-like hormones, called adipokines, either pro- or anti-inflammatory factors bridging metabolism to the immune system. Leptin is historically one of most relevant adipokines, with important physiological roles in the central control of energy metabolism and in the regulation of metabolism-immune system interplay, being a cornerstone of the emerging field of immunometabolism. Indeed, leptin receptor is expressed throughout the immune system and leptin has been shown to regulate both innate and adaptive immune responses. This review discusses the latest data regarding the role of leptin as a mediator of immune system and metabolism, with particular emphasis on its effects on obesity-associated metabolic disorders and autoimmune and/or inflammatory rheumatic diseases.

Adipokines and inflammation: is it a question of weight?

Obesity has reached epidemic proportions in the Western society and is increasing in the developing world. It is considered as one of the major contributors to the global burden of disability and chronic diseases, including autoimmune, inflammatory and degenerative diseases. Research conducted on obesity and its complications over the last two decades has transformed the outdated concept of white adipose tissue (WAT) merely serving as an energy depot. WAT is now recognized as an active and inflammatory organ capable of producing a wide variety of factors known as adipokines. These molecules participate through endocrine, paracrine, autocrine or juxtacrine crosstalk mechanisms in a great variety of physiological or pathophysiological processes, regulating food intake, insulin sensitivity, immunity and inflammation. Although initially restricted to metabolic activities (regulation of glucose and lipid metabolism), adipokines currently represent a new family of proteins that can be considered key players in the complex network of soluble mediators involved in the pathophysiology of immune/inflammatory diseases. However, the complexity of the adipokine network in the pathogenesis and progression of inflammatory diseases has posed, since the beginning, the important question of whether it may be possible to target the mechanism(s) by which adipokines contribute to disease selectively without suppressing their physiological functions. Here, we explore in depth the most recent findings concerning the involvement of adipokines in inflammation and immune responses, in particular in rheumatic, inflammatory and degenerative diseases. We also highlight several possible strategies for therapeutic development and propose that adipokines and their signalling pathways may represent innovative therapeutic strategies for inflammatory disorders.

Influence of serum leptin levels and Q223R leptin receptor polymorphism on clinical characteristic of patients with rheumatoid arthritis from Western Mexico

OBJECTIVE

The aim of the present study was to evaluate the possible association between the Q223R Leptin receptor (LEPR) polymorphism (A>G; rs1137101) and leptin levels in patients with rheumatoid arthritis (RA) from Western Mexico.

METHODS

A cross-sectional study was performed with 70 RA patients and 74 controls subject (CS). Disease activity was evaluated using DAS28 score, the Q223R LEPR polymorphism was determined by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and serum leptin levels, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and rheumatoid factor (RF) were quantified.

RESULTS

RA patients had significant high serum leptin levels compared with CS; leptin levels correlated strongly with body composition measures, but not with inflammatory markers, disease evolution, and activity. The genotype and allele frequencies of the Q223R LEPR polymorphism were not associated with RA. Similarly, leptin levels did not differ between Q223R LEPR genotypes.

CONCLUSION

The LEPR Q223R polymorphism was not associated with RA risk in patients from Mexican population, even though high levels of serum leptin were present and these could explain the low weight observed in RA patients when they were compared to control subjects. However, the serum leptin levels did not correlate with inflammatory markers, severity and disease evolution.

Leptin Upregulates Peripheral CD4+CXCR5+ICOS+ T Cells via Increased IL-6 in Rheumatoid Arthritis Patients

CD4⁺CXCR5⁺ICOS⁺ T cells, known as Tfh (T Follicular helper) cells, are required for antibody production. Abnormal production and differentiation of Tfh cells are involved in many autoimmune diseases, including rheumatoid arthritis (RA). Leptin has the property of modulating immune system. Here, we explored the effect of leptin on CD4⁺CXCR5⁺ICOS⁺ T cells production in RA patients. Serum leptin levels were measured by enzyme-linked immunosorbent assay (ELISA). Peripheral blood mononuclear cells (PBMC) stimulated with CD3/CD28 were cultured in the presence and absence of leptin and with or without anti-IL-6 receptor (anti-IL-6R), anti-IL-21R, and anti-IL-12R antibody respectively. IL-6, IL-21, and IL-12 levels were determined by ELISA. Bcl-6 was detected by reverse transcription-polymerase chain reaction. STAT1, pSTAT1, STAT3, and pSTAT3 were examined by western blot. We found that leptin levels were higher in RA patients than healthy controls. Leptin-stimulated RA PBMC upregulated CD4⁺CXCR5⁺ICOS⁺ T cells, along with increased IL-6, IL-21, and IL-12.CD4⁺CXCR5⁺ICOS⁺ T cells, Bcl-6 mRNA expression, pSTAT1, and pSTAT3 obviously declined when anti-IL-6R antibody was added into leptin-treated RA PBMC, which suggested that leptin upregulated RA CD4⁺CXCR5⁺ICOS⁺ T cells via increased IL-6 by activation of STAT1 and STAT3. We presented an innovative mechanism on how leptin participated in RA pathogenesis.

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.

Leptin-induced migration and angiogenesis in rheumatoid arthritis is mediated by reactive oxygen species

Rheumatoid arthritis (RA) is a progressive autoimmune disease affecting the joints. In this study, we investigated the role of the pro‐angiogenic factor leptin in regulating reactive oxygen species (ROS) to promote cell migration and angiogenesis in RA. We showed that leptin triggered RA fibroblast‐like synoviocyte (FLS) migration by increased ROS expression. Additionally, leptin enhanced human umbilical vein endothelial cell (HUVEC) tube formation in a ROS/hypoxia‐inducible factor‐1α‐dependent manner, accompanied by increased production of vascular endothelial growth factor and interleukin (IL)‐6. We also revealed that antagonists of tumor necrosis factor, IL‐6 and IL‐1β down‐regulated ROS production of RA FLS induced by leptin, which subsequently attenuated RA FLS migration and HUVEC tube formation. These findings demonstrated that leptin might play an important role in RA FLS migration and HUVEC angiogenesis.

Association between leptin and IL-6 concentrations with cardiovascular risk in patients with rheumatoid arthritis

Pro-inflammatory cytokines such as leptin and IL-6 play an important role in the development of cardiovascular risk. Determine the relationship between leptin and IL-6 concentrations with cardiovascular risk in patients with rheumatoid arthritis. We determined IL-6 and leptin levels in 77 patients with the diagnosis of rheumatoid arthritis. The cardiovascular risk was calculated using the modified Framingham scale. Statistical analysis was performed using SPSS 22 considering a significant p < 0.05. Serum leptin concentrations and cardiovascular risk (CVR) factors were compared and found that there was a significant difference between higher leptin values and disease activity (p 0.047), obesity (p 0.038), positive rheumatoid factor (p 0.009), tobacco (p 0.009), and metabolic syndrome (p 0.001). Likewise, a significant relationship was found between lower leptin concentrations and hydroxychloroquine consumption (p = 0.023). We found significant difference between IL-6 concentrations and disease activity (p 0.028), hypertriglyceridemia (p 0.023), LDL-C (p 0.029), and smoking (0.005). Similarly, an association between hydroxychloroquine consumption and low concentrations of IL-6 was found (p 0.005). Framingham CVR was calculated and the result obtained was multiplied by 1.5. The 35.2% of the population studied had a low Framingham CVR, 38.9% moderate, and 25.9% presented a high risk. We compared the level of CVR and serum leptin and IL-6 concentrations, finding that the highest CVR was the leptin and IL-6 values. There is a positive association between CVR and serum leptin concentrations. It is also significantly associated with traditional and non-traditional risk factors.

Association between circulating leptin levels and systemic lupus erythematosus: an updated meta-analysis

Objective We aimed to evaluate the relationship between circulating leptin levels and systemic lupus erythematosus (SLE). Methods MEDLINE, EMBASE, and Cochrane library databases were searched. Meta-analyses were performed comparing serum/plasma leptin levels in patients with SLE and healthy controls, and on patients with SLE in subgroups based on ethnicity, sample size, data type, and matched variables (age, sex, and/or body mass index (BMI)). Results Eighteen studies including 1333 patients with SLE and 1048 controls were ultimately selected, which showed that leptin levels were significantly higher in the SLE group than in the control group (SMD = 0.611, 95% CI = 0.275-0.947, p < 0.001). When we excluded two outlier studies because of high heterogeneity, leptin levels were also significantly higher in the SLE group than in the control group (SMD = 0.619, 95% CI = 0.431-0.807, p < 0.001). Stratification by ethnicity showed significantly elevated leptin levels in the SLE group in European, Asian, Arab, Latin American, and mixed populations. Subgroup analysis by sample size showed significantly higher leptin levels in the SLE group by small ( n ≤ 100) and large sample numbers ( n > 100) (SMD = 0.780, 95% CI = 0.445-1.115, p < 0.001; SMD = 0.495, 95% CI = 0.275-0.715, p < 0.001). Stratification by data type revealed significantly higher leptin levels in the original data and imputed data groups. Subgroup analysis adjustment revealed significantly higher leptin levels in the SLE group, regardless of adjustment for variables. Conclusions Our meta-analysis demonstrated that leptin levels were significantly higher in patients with SLE, regardless of ethnicity, sample size, data type, and matched variables.

Circulating leptin level in rheumatoid arthritis and its correlation with disease activity: a meta-analysis

OBJECTIVE

This study aimed to evaluate the relationship between the circulating serum leptin level and rheumatoid arthritis (RA) and to establish a correlation between serum leptin levels and RA activity.

METHODS

We searched the PUBMED, EMBASE, and Cochrane databases. A meta-analysis was performed, comparing the serum/plasma leptin levels in patients with RA and healthy controls. Correlation coefficients between serum leptin level and either disease activity score 28 (DAS28) or C‑reactive protein (CRP) in RA patients were also examined.

RESULTS

Thirteen studies with a total of 648 RA patients and 426 controls were included in this meta-analysis. Circulating leptin level was significantly higher in the RA group than in the control group (SMD = 1.056, 95 % CI = 0.647-1.465, p = 4.2 × 10^-7). In addition, stratification by ethnicity showed a significantly elevated leptin level in the RA group in Caucasian, Turkish, and Arab populations (SMD = 0.813, 95 % CI = 0.137-1.490, p = 0.018, SMD = 0.981, 95 % CI = 0.307-1.655, p = 0.004, and SMD = 1.469, 95 % CI = 0.443-2.495, p = 0.005 respectively). A meta-analysis of correlation coefficients showed a small but significantly positive correlation between the circulating leptin level and either DAS28 (correlation coefficient = 0.275, 95 % CI = 0.076-0.452, p = 0.007) or CRP (correlation coefficient = 0.274, 95 % CI = 0.068-0.458, p = 0.010).

CONCLUSIONS

Our meta-analysis demonstrated that the circulating leptin level is significantly higher in patients with RA and that a small but significantly positive correlation exists between leptin levels and RA activity.

Hidradenitis suppurativa: from pathogenesis to diagnosis and treatment

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease primarily affecting apocrine gland-rich areas of the body and presenting with painful nodules, abscesses, sinus tracts, and scarring. HS is a multifactorial disease in which genetic and environmental factors play a key role. The primary defect in HS pathophysiology involves follicular occlusion of the folliculopilosebaceous unit, followed by follicular rupture, and immune responses (perifollicular lympho-histiocytic inflammation), finally leading to the development of clinical HS lesions. HS has a destructive impact on the patient’s quality of life, being a very challenging disease. Available treatments are limited, mostly off-label and with high variability in the reported efficacy. Fortunately, a monoclonal antibody against tumor necrosis factor alpha has been recently approved for treatment of moderate to severe HS, offering patients a promising new option. This review focuses on the main features of HS, including epidemiology, clinical aspects, pathogenesis, severity classifications, comorbidities, and currently available treatments.

Medical and Surgical Treatment of Hidradenitis Suppurativa: A Review

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease presenting with painful nodules, abscesses, sinus tracts, and scarring primarily affecting apocrine gland-rich intertriginous areas. HS prevalence ranges from 0.05 to 1%. The central pathogenic event in HS is believed to be the occlusion of the upper part of the folliculopilosebaceous unit, leading to the rupture of the sebofollicular canal with the consequent development of perifollicular lymphohistiocytic inflammation. The HS treatment choices are influenced by disease severity and its individual subjective impact, involving both medical and surgical interventions. However, given the chronic nature of HS, its destructive impact on social, working, and daily life of patients, its management is often frustrating for both the patient and physician. Hence, prompt and effective management strategies are urgently needed and a multidisciplinary approach is advocated. Therefore, in this article, we highlighted the main features of HS (clinical aspects, epidemiology, pathogenesis, diagnostic criteria, classifications, comorbidities, and treatments), so that awareness of this disease might be heightened in primary care physicians and surgeons, who may be the first health care providers to see patients with this disease owing to its characteristic clinical presentation (inflammatory nodules, abscesses, sinus tract, etc.).

Absence of a positive correlation between CRP and leptin in rheumatoid arthritis

Aims

Rheumatoid Arthritis (RA) is a model of chronic inflammatory disease. In this study we evaluated the correlation of leptin and CRP in patients with RA and normal controls.

Main methods

A total of 75 patients with RA and 40 healthy adults were recruited in this case-control study. RA patients were categorized into high (DAS–28 > 3.2) and low activity (DAS ≤ 3.2) group according to their DAS-28 score.

Key findings

Leptin level was significantly correlated with CRP in healthy controls (r = 0.365; p < 0.05), but this correlation was lost in RA patients (r = 0.095, p = 0.41). Patients with RA had higher serum leptin levels compared to healthy controls (P < 0.01). No difference in serum leptin level was observed between patients with high and low activity disease. Also leptin was correlated with BMI in healthy controls (r = 0.326, p = 0.037). This correlation was not present in RA patients (r = 0.039, p = 0.756).

Significance

We observed that the physiologic correlation between leptin and CRP and BMI and CRP was not present RA patients. This is a new study reporting the lost correlation between leptin and CRP in RA patients.

Baseline adiponectin and leptin levels in predicting an increased risk of disease activity in rheumatoid arthritis: A meta-analysis and systematic review

To determine the pathogenic role of adipokines, such as adiponectin and leptin, in rheumatoid arthritis (RA) by investigating whether serum levels of these adipokines correlated with disease activity in RA patients. Medline, Cochrane, EMBASE and Google Scholar were searched for studies published until 5 November 2015 reporting serum levels of leptin and adiponectin and measures of disease activity including DAS scores and radiographic progression scores (such as total change in SHS scores and number of erosions). Secondary outcomes included pain scores, functional status and health questionnaires. Only randomized controlled trials, cohort studies, or two-armed prospective or retrospective studies were included. A χ²-based test of homogeneity was performed using Cochran's Q statistic and I². A total of 917 predominantly female participants (average age range, 39-56 years) from six prospective cohort studies were included for assessment. A fixed-effects analysis was applied for leptin levels due to lack of heterogeneity among the studies (Q = 4.4364; I²=32.38). A random-effects analysis was applied to serum levels of adiponectin because of significant heterogeneity between studies (Q = 4.444, I²=77.50%). Serum leptin levels were higher in RA patients with high disease activity (pooled SMD: 0.53, 95% CI: 0.24-0.82); however, serum adiponectin levels did not correlate with RA disease activity (pooled OR: 1.38, 95% CI: 0.77-2.47). The meta-analysis provides an additional factor to determine high disease activity index in RA, that is, serum leptin levels, which can be of benefit when choosing treatment strategies.

Serum adipokines levels in patients with systemic sclerosis: A meta-analysis

BACKGROUND

Systemic sclerosis is an chronic inflammatory autoimmune diseases. Adipokine has been reported to play an important role in modulating immune responses. Recent studies suggest that adipokine also plays some roles in the pathogenesis of systemic sclerosis (SSc). However, published data regarding the relationship between plasma/serum adipokine levels and SSc are contradictory. The aim of this study was at performing a meta-analysis to derive a more accurate estimation and further investigate the association of plasma/serum leptin and adiponectin levels with SSc patients.

METHODS

PubMed, and Web of Science databases (up to Feb 20, 2016) were used to obtain all relative published literatures. The study quality was assessed by the Newcastle-Ottawa scale. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by random-effect model analysis.

RESULTS

A total of fourteen studies were finally included in this meta-analysis. Among them, six of which were studied for the serum adiponectin levels in SSc patients, six of which were studied for the serum leptin levels in SSc patients, and two of them were studied both for serum adiponectin levels and serum leptin levels in SSc patients. The meta-analysis results showed that the serum adiponectin levels in SSc patients were significantly lower than that in normal controls (SMD = -0.608 ng/ml, 95% CI = -1.029 to -0.186, p = 0.005). However, there were no significant differences in serum leptin levels between SSc patients and healthy controls (SMD = -0.990 ng/ml, 95% CI = -2.340 to 0.359, p = 0.150). The subgroup analysis showed that Asia SSc patients with age less than 50 years old had lower plasma/serum adiponectin levels when compared with controls.

CONCLUSION

The serum adiponectin levels, but not serum leptin levels, in SSc patients were significantly lower than that in normal controls.

Evaluation of switching from intravenous to subcutaneous formulation of tocilizumab in patients with rheumatoid arthritis

OBJECTIVE

To evaluate the efficacy of switching the route from intravenous tocilizumab (TCZ) infusion (TCZ-IV) to subcutaneous TCZ injection (TCZ-SC) in a real-world setting through a comparison of the clinical response.

METHODS

Fifty-eight rheumatoid arthritis (RA) patients, for whom TCZ-SC was initiated following TCZ-IV between June 2013 and August 2014, were consecutively enrolled. Disease activity score (DAS)28-ESR, simplified disease activity index (SDAI), and clinical disease activity index (CDAI) were examined at baseline and after switching from TCZ-IV to TCZ-SC for 3 months. We investigated whether body weight and body mass index (BMI) affected the efficacy of TCZ-SC.

RESULTS

Most of the patients had achieved remission or low disease activity at baseline (77.6% examined by DAS28). Fifty-seven patients (98%) continued the TCZ-SC treatment, and the disease activity was well controlled after 3 months. ΔDAS28 tended to be worsened after switching to TCZ-SC in the high-body-weight groups (≥60 kg) as compared with the groups with body weight <60 kg, although no statistical significance was found. BMI did not affect the efficacy of TCZ-SC.

CONCLUSIONS

Caution should be exercised in the high-body-weight subjects, but these data indicate that TCZ-SC maintains the favorable RA disease activity established using TCZ-IV.