Serum leptin in systemic lupus erythematosus

High serum leptin and adiponectin levels as biomarkers of disease progression in Egyptian patients with active systemic lupus erythematosus

Objectives: Leptin and adiponectin are adipose-derived immune modulators (adipokines) that may contribute to SLE pathology and symptoms. This study aimed to evaluate the associations of serum adiponectin and leptin with clinical manifestations and disease activity in SLE patients. Methods: This is a case control study, where 70 SLE patients and 50 age- and sex-matched healthy controls were enrolled from the Rheumatology and Rehabilitation Department of Beni-Suef University Hospital from June 2020 till April 2022. The SLE disease activity index (SLEDAI) and Systemic Lupus International Collaborative clinics/America Collage of Rheumatology damage index were used to assess disease severity. Laboratory parameters including erythrocyte sedimentation rate (ESR) and serum concentrations of antinuclear antibody (ANA), anti-double stranded DNA, complement 3 and 4, lipids, and C-reactive protein (CRP) were measured and compared between SLE and control groups. Serum adiponectin and leptin were also measured by enzyme-linked immunosorbent assays (ELISA). Results: Compared to healthy controls, SLE patients exhibited significantly greater serum leptin (21.1 vs 3.9 ng/mL, p < 0.001) and adiponectin (18.1 vs 4.8 ng/mL, p < 0.001), and both values were positively correlated with SLEDAI scores (p = 0.048 and 0.042). Higher serum leptin was significantly associated with lupus nephritis (LN) (p = 0.048) as well as greater body mass index (p = 0.010), ESR (p = 0.002), serum CRP (p = 0.003), total cholesterol (p = 0.013), and uric acid (p = 0.002), while higher adiponectin was significantly associated with LN (p = 0.046). Conclusion: Serum leptin and adiponectin levels are associated with the clinical and pathological manifestations of SLE, suggesting direct involvement in disease progression and utility as diagnostic biomarkers and therapeutic targets.

Non-Traditional Pro-Inflammatory and Pro-Atherosclerotic Risk Factors Related to Systemic Lupus Erythematosus

Cardiovascular diseases (CVD) are one of the leading causes of high mortality in patients with systemic lupus erythematosus (SLE). The Framingham risk score and other traditional risk factors do not fully reflect the CVD risk in SLE patients. Therefore, in order to stratify these high-risk patients, additional biomarkers for subclinical CVD are needed. The mechanisms of atherogenesis in SLE are still being investigated. During the past decades, many reports recognized that inflammation plays a crucial role in the development of atherosclerosis. The aim of this report is to present novel proinflammatory and pro-atherosclerotic risk factors that are closely related to SLE inflammation and which determine an increased risk for the occurrence of early cardiovascular events.

Cardiovascular disease in systemic lupus erythematosus

There is a well-known increased risk for cardiovascular disease that contributes to morbidity and mortality in systemic lupus erythematosus (SLE). Major adverse cardiovascular events and subclinical atherosclerosis are both increased in this patient population. While traditional cardiac risk factors do contribute to the increased risk that is seen, lupus disease-related factors, medications, and genetic factors also impact the overall risk. SLE-specific inflammation, including oxidized lipids, cytokines, and altered immune cell subtypes all are likely to play a role in the pathogenesis of atherosclerotic plaques. Research is ongoing to identify biomarkers that can help clinicians to predict which SLE patients are at the greatest risk for cardiovascular disease (CVD). While SLE-specific treatment regimens for the prevention of cardiovascular events have not been identified, current strategies include minimization of traditional cardiac risk factors and lowering of overall lupus disease activity.

The role of leptin in selected skin diseases

Leptin is an adipokine, adipocyte-derived compound, which acts both as a hormone and cytokine. It is mainly synthesized by adipocytes of white adipose tissue. Leptin possesses pleiotropic functions including, among others, stimulation of angiogenesis and production of proinflammatory cytokines. The various types of leptin activity are related to the wide distribution of leptin receptors. This adipokine acts by activating intracellular signaling cascades such as JAKs (Janus kinases), STATs (signal transducers and activators of transcription), and others.In a course of obesity, an increased serum level of leptin coexists with tissue receptor resistance. It has been reported that enhanced leptin levels, leptin receptor impairment, and dysfunction of leptin signaling can influence skin and hair. The previous studies revealed the role of leptin in wound healing, hair cycle, and pathogenesis of skin diseases like psoriasis, lupus erythematosus, and skin cancers. However, the exact mechanism of leptin's impact on the skin is still under investigation. Herein, we present the current knowledge concerning the role of leptin in psoriasis and selected skin diseases.

Role of serum leptin levels and leptin receptor gene polymorphisms in systemic lupus erythematosus

BACKGROUND

Serum leptin and leptin receptor gene polymorphisms may play a role in the etiopathogenesis of SLE.

OBJECTIVE

This study was undertaken to explore the relationship between serum leptin levels and leptin receptor (LEPR) gene polymorphisms with susceptibility to SLE in Egyptian population and to study their relationships with clinical, laboratory, radiographic findings, and disease activity of SLE (SLEDAI).

MATERIALS AND METHODS

A total of 50 unrelated female patients, who met the SLICC classification criteria for SLE and fifty healthy blood donors, matched for age, sex, and BMI with SLE patients, serving as a control group, were included in this study. All participants had completed preliminary questionnaires and clinical, laboratory, and radiographic examinations. Serum leptin levels were measured by ELISA assays. LEPR genotyping was done by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method. We compared serum leptin levels and LEPR gene polymorphisms in SLE patients and controls, and we tested their relationships with clinical, laboratory, and radiographic findings and SLEDAI in SLE patients.

RESULTS

The present study showed significant differences of serum leptin levels between SLE patients and controls (p < 0.001). Moreover, higher frequencies of variant genotype (AA) and (A) allele were found in SLE patients compared to controls (p = 0.008 and 0.001, respectively). No associations were observed between the serum leptin, various LEPR genotypes, and gene alleles and the development of clinical, laboratory, and radiological manifestations. Furthermore, no associations were observed between the various LEPR genotypes or gene alleles and leptin levels (p = 0.633 and 0.337 respectively) in SLE patients. Additionally, no correlations were observed between leptin levels, various genotypes, and alleles with SLEDAI (p = 0.244, 0.741, and 0.838 respectively) in SLE patients.

CONCLUSION

Serum leptin and LEPR gene polymorphism increase risk of SLE in Egyptian population; however, they are not associated with the development of clinical, lab, and radiological findings. Disease activity is neither correlated with serum leptin level nor associated with LEPR gene polymorphism. Serum levels of leptin are not associated with LEPR gene polymorphism. Key Points • Serum leptin and LEPR gene polymorphism increase risk of SLE in Egyptian patients. • Serum leptin is not associated with SLE disease activity.

Serum adipokine levels in patients with sarcoidosis

BACKGROUND

Sarcoidosis is a chronic inflammatory disease characterized by non-caseating granuloma which etiology is unknown yet. Adipokines are different proteins synthesized by adipose tissue that have an influence on angiogenesis, hemostasis, lipid metabolism, and immune system regulation. Adipokines may play a role in the pathogenesis of sarcoidosis.

OBJECTIVES

To evaluate the serum adipokine levels in patients with sarcoidosis and to determine a possible correlation with clinical and laboratory signs of disease.

METHODS

Forty-four biopsy-proven sarcoidosis patients followed at a single center and age- and sex-matched 41 healthy volunteers were included in the study. Demographic, clinical, laboratory, and radiological data were recorded and body mass index (BMI) was calculated in all patients. Routine laboratory tests (blood glucose, liver, and kidney function test) were measured. Serum adiponectin and leptin levels were measured by ELISA method.

RESULTS

Among 44sarcoidosis patients, 13 (29.5%) were male and 31 (70.5%) were female. Twenty-one (47.7%) patients had erythema nodosum, three (6.8%) had uveitis, 40 (90.9%) had arthralgia, 32 (72.7%) had arthritis, 15 (34.1%) had enthesitis. Laboratory evaluation showed increased serum ACE level in 24 (54.5%) patients, increased serum calcium level in 11 (25%) patients, increased serum D3 level in 5 (11.4%) patients, and increased ESR and CRP levels in 22 (50%) and 23 (52.3%) patients, respectively. Compared with the control group, serum adiponectin levels were significantly higher in patients with sarcoidosis(p = 0.007). Serum adiponectin level was associated with arthralgia and ankle joint swelling (p = 0.007, p = 0.006 respectively). Serum leptin levels were similar in sarcoidosis patients and controls (p = 0.327). There was no relationship between serum leptin level and disease features (p > 0.05).

CONCLUSIONS

In this study, high serum adiponectin level was detected in patients with sarcoidosis while serum leptin level was similar in the sarcoidosis and control group. Adiponectin, an anti-inflammatory protein, may play a role in the pathogenesis of sarcoidosis. Studies are needed to shed light on this topic.Key Points• Sarcoidosis is a chronic granulomatous disease characterized by granuloma formation• High serum adiponectin level was found in sarcoidosis patients• Serum adiponectin level was associated with some clinical features such as arthralgia and arthritis• High adiponectin levels in sarcoidosis patients may mitigate the inflammatory response, resulting in a mild form of the disease and/or spontaneous remission.

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.

Metabolic syndrome and systemic lupus erythematosus: the connection

Introduction: The metabolic syndrome (MetS) is now recognized as a chronic proinflammatory and prothrombotic state that aggravates insulin resistance, oxidative injury, and cardiovascular risk. MetS is more prevalent in patients with systemic lupus erythematosus (SLE), a prototype of systemic autoimmune disease associated with premature atherosclerosis that cannot be accounted by traditional vascular risk factors alone. Dysregulation of the cytokines and adipokines is a common feature in both SLE and MetS, suggesting a complex relationship among autoimmunity, obesity, inflammation, and atherosclerosis. Areas covered: This review summarizes the prevalence of MetS and its effect on cardiovascular outcome and organ damage in patients with SLE. The pathophysiology of MetS and its relevance to SLE is also briefly discussed. Expert opinion: Imbalance of adipokine production in MetS contributes to inflammation and atherosclerosis. MetS predisposes SLE patients to new cardiovascular events and vascular mortality, as well as the development of chronic kidney disease and diabetes mellitus. However, conflicting results have been reported in the literature regarding the levels of the proinflammatory leptin and anti-inflammatory adiponectin, and their relationship with disease activity in SLE patients. While lifestyle modifications and targeting dyslipidemia, hypertension and diabetes mellitus is essential, there is little information on the efficacy and safety of metformin and hydroxychloroquine in alleviating insulin resistance in SLE or MetS. Further research on adipokines in SLE and the role of anti-obesity medications and probiotics in MetS is necessary.

What is the role of adipokines in myasthenia gravis?

Objective

Myasthenia gravis (MG) is a disease with autoimmune etiology. The main pathomechanism is related to the production of antibodies against nicotinic acetylcholine receptor. The present study is aimed to compare the serum level of adipokines in patients with MG with that in controls, as well as to study the relation of these levels with disease severity.

Patients and methods

Fifty patients with MG and 30 healthy individuals were enrolled in our study. Serum concentrations of select adipokines, namely adiponectin, leptin, omentin, visfatin, and resistin were measured.

Results

The results showed a significant increase in serum concentrations of adiponectin and resistin in the patients with MG compared with the controls.

Conclusion

Further studies are warranted to assess changes in adipokine concentration levels in patients with MG.

The relationship between serum leptin level and disease activity and inflammatory markers in fibromyalgia patients

OBJECTIVE

The aim of this study was to investigate whether there is a correlation between serum leptin level, disease activity and inflammation markers in patients with fibromyalgia syndrome (FMS).

METHODS

A total of 48 patients with FMS diagnosed according to the 1990 American College of Rheumatology criteria were included in the study, as well as 36 healthy women as controls. The Visual Analogue Scale was used to gauge pain severity, the Fibromyalgia Impact Questionnaire was used to assess physical function, the 36-Item Short Form Health Survey was used to examine quality of life, and depression was measured with the Beck Depression Inventory. Blood samples were examined for erythrocyte sedimentation rate (ESR), C-reactive protein level (CRP), high-sensitivity CRP level (hsCRP), the neutrophil-to-lymphocyte ratio (NLR), and the serum leptin level was determined using the enzyme-linked immunosorbent assay method.

RESULTS

The serum leptin level in patients with FMS was significantly higher than in the healthy group. However, no significant relationship was found between leptin level and clinical and inflammatory parameters. In addition, there were no significant differences between the patients and the control group in measurements of ESR, CRP, hsCRP, or NLR.

CONCLUSION

A higher serum leptin level in patients with FMS suggested that leptin may play role in the pathogenesis of FMS, yet there was no relationship between leptin and clinical and inflammatory parameters, suggesting that leptin is not an indicator of disease activity in FMS. Additional research should be performed with larger patient groups.

Salivary biomarkers of inflammation in systemic lupus erythematosus

Saliva is currently used as a reliable diagnostic fluid in a wide range of local and systemic diseases. However, the link between salivary diagnosis and the inflammatory process in autoimmune diseases has not yet been explored. The aim of our study is to assess possible correlations between salivary inflammatory markers and systemic lupus erythematosus (SLE). Patients fulfilling the Systemic Lupus International Collaborating Clinics (SLICC) diagnosis criteria were included. Salivary and serum levels of interleukin-6 (IL-6), leptin, monocyte chemoattractant protein-1 (MCP-1) and plasminogen activator inhibitor-1 (PAI-1) were determined using stochastic sensors. Serum leptin and IL-6 had significantly higher levels in SLE patients compared to non-SLE. Also, salivary IL-6 levels highly correlated with the serum IL-6 levels. A positive correlation was found between salivary and serum levels of IL-6, signaling salivary IL-6 as a reliable marker for assessing the inflammation process in SLE.

Leptin in autoimmune mechanisms of systemic rheumatic diseases

In the last two decades, white adipose tissue (WAT) has been recognized as a key actor of many physiological and pathological conditions. WAT is able to produce mediators, named "adipokines", which may affect systemic homeostasis. In particular, leptin is not only involved in appetite and energy metabolism, but also in immune system. Increasing evidence established that leptin can regulate both innate and adaptive immunity mainly with pro-inflammatory effects but also, to a lesser extent, with anti-inflammatory features. In autoimmune diseases, a failure or breakdown of the mechanisms of self-tolerance is observed. Leptin, which plays an important role in the control of immune balance, has been involved in autoimmunity generation and maintenance. In this review, it has been provided an up-to-date report about the role of leptin in systemic autoimmune diseases, with particular reference to connective tissue diseases, inflammatory arthritis, and vasculitis.

Emerging role of adipokines in systemic lupus erythematosus

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

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.

Leptin levels in patients with systemic lupus erythematosus inversely correlate with regulatory T cell frequency

Leptin levels are increased in patients with systemic lupus erythematosus (SLE) but little is known on how this correlates with several disease characteristics including the frequency of regulatory T cells (Tregs). Here we compared serum leptin levels with frequency of circulating Tregs in 47 lupus patients vs. 25 healthy matched controls. Correlations with lupus disease activity were also analyzed, as well as Treg proliferation potential. It was found that leptin was remarkably increased in SLE patients as compared to controls, particularly in SLE patients with moderate and severe active SLE, and the increase correlated with disease activity. Importantly, increased leptin in lupus patients inversely correlated with the frequency of Tregs but not in controls, and leptin neutralization resulted in the expansion of Tregs ex vivo. Thus, hyperleptinemia in lupus patients correlates directly with disease activity and inversely with Treg frequency. The finding that leptin inhibition expands Tregs in SLE suggests possible inhibition of this molecule for an enhanced Treg function in the disease.

Association of leptin and leptin receptor gene polymorphisms with systemic lupus erythematosus in a Chinese population

To explore the association of LEP and leptin receptor (LEPR) gene single‐nucleotide polymorphisms (SNPs) with susceptibility to systemic lupus erythematosus (SLE) in a Chinese population. Four LEPSNPs (rs11761556, rs12706832, rs2071045 and rs2167270) and nine LEPRSNPs (rs10749754, rs1137100, rs1137101, rs13306519, rs8179183, rs1805096, rs3790434, rs3806318 and rs7518632) were genotyped in a cohort of 633 patients with SLE and 559 healthy controls. Genotyping of SNPs was performed with improved multiple ligase detection reaction (iMLDR). No significant differences were detected for the distribution of allele and genotype frequencies of all 13 SNPs between patients with SLE and controls. The genotype effects of recessive, dominant and additive models were also analysed, but no significant evidence for association was detected. However, further analysis in patients with SLE showed that the TT genotype and T allele frequencies of the LEP rs2071045 polymorphism were nominally significantly higher in patients with pericarditis (P = 0.012, P = 0.011, respectively). In LEPR, the GA/AA genotype and A allele frequencies of the rs1137100 polymorphism were both nominally associated with photosensitivity in patients with SLE (P = 0.043, P = 0.018, respectively). Moreover, the genotype and allele distribution of rs3806318 were also nominally associated with photosensitivity in patients with SLE (P = 0.013, P = 0.008, respectively). No significant differences in serum leptin levels were observed in patients with SLE with different genotypes. In summary, LEP and LEPRSNPs are not associated with genetic susceptibility to SLE, but may contribute to some specific clinical phenotype of this disease; further studies are necessary to elucidate the exact role of LEP and LEPR genes in the pathogenesis of SLE.

Adipokines, tumor necrosis factor and its receptors in female patients with systemic lupus erythematosus

OBJECTIVES

To analyze the association of adipokines and tumor necrosis factor α (TNFα) and its receptors with characteristics of systemic lupus erythematosus (SLE) and to investigate the correlation between adipokines and the TNF system.

METHODS

One hundred and thirty-six SLE women, aged ≥18 years old, were assessed. TNFα, soluble TNFα receptors 1 (sTNFR1) and 2 (sTNFR2) and adipokines were analyzed by ELISA kits.

RESULTS

The median (IQR) of age was 41.5 (33.0-49.7) years old and of disease duration 11.3 (7.8-15.8) years. The median (IQR) of disease activity was 0 (0-4) and of damage index was 2 (1-3). Higher levels of sTNFR1 and sTNFR2 were associated with nephritis (p < 0.001 for both), and sTNFR1 (p = 0.025) and TNFα (p = 0.014) were positively associated with arthritis. Higher sTNFR1 levels were found in participants that were not using antimalarial drugs (p = 0.04). Independent correlation was found between sTNFR1 (β = 0.253; p = 0.003) and sTNFR2 (β = 0.297; p < 0.001) levels and disease activity and damage index (sTNFR1: β = 0.367; p < 0.001; sTNFR2: β = 0.335; p < 0.001). Higher adiponectin levels were independently associated with nephritis (p = 0.009) and antimalarial drugs use (p = 0.015). There was a positive correlation between leptin and sTNFR2 levels (p = 0.002) and between resistin levels and sTNFR1 (p < 0.001) and sTNFR2 (p < 0.001).

CONCLUSION

The correlation between adipokines and TNF system allows a better understanding of the role of adipokines in the inflammatory response in SLE patients.

Resistin as a potential marker of renal disease in lupus nephritis

Systemic lupus erythematosus (SLE) and lupus nephritis (LN) have strong concomitance with cardiovascular disease that cannot be explained fully by typical risk factors. We examined the possibility that serum or urine expression of adipokines may act as biomarkers for LN, as these proteins have been associated previously with cardiovascular disease as well as SLE. Antibody arrays were performed on serum and urine from lupus patients and matched controls using a cross-sectional study design. From the initial array-based screening data of 15 adipokines, adiponectin, leptin and resistin were selected for validation by enzyme-linked immunosorbent assay (ELISA). Correlations were determined between adipokine expression levels and measures of disease activity or lupus nephritis. The expression of adiponectin and resistin was increased in both sera and urine from LN patients, while leptin was increased in LN patient sera, compared to matched controls. Serum resistin, but not urine resistin, was correlated with measures of renal dysfunction in LN. Serum resistin expression may be useful as a marker of renal dysfunction in patients with LN, although longitudinal studies are warranted. Further studies are necessary to determine if resistin has functional consequences in LN.

Fish oil N-3 fatty acids increase adiponectin and decrease leptin levels in patients with systemic lupus erythematosus

Cardiovascular disease (CVD) has emerged as an important cause of death in patients with systemic lupus erythematosus (SLE). Reduced adiponectin and elevated leptin levels may contribute to CVD in SLE patients. The purpose of this study was to verify the effects of fish oil (FO) on adiponectin and leptin in patients with SLE. Biochemical and disease activity analysis were performed. Patients with SLE were divided in two groups: patients who used fish oil for four months and patients who did not use fish oil. Patients with SLE who used FO had a significant decrease in SLE disease activity index (SLEDAI) score (p ˂ 0.023) in relation to baseline. SLE patients who used fish oil had increased adiponectin levels (p ˂ 0.026) and decreased leptin levels (p ˂ 0.024) compared to baseline values, whereas there were no differences in adiponectin and leptin levels in patients with SLE who did not use fish oil. In conclusion, the findings of increased serum adiponectin an decreased leptin levels after 120 days in the fish oil group, reinforce the importance of evaluating prospective studies of fish and fish oil fish ingestion on these adipokines in an attempt to decrease cardiovascular risk factors in patients with SLE.

Leptin in autoimmune diseases

The past twenty years of research on leptin has provided crucial information on the link between metabolic state and immune system function. Adipocytes influence not only the endocrine system but also the immune response, through several cytokine-like mediators known as adipokines, which include leptin. Initially described as an antiobesity hormone, leptin has subsequently been shown also to influence hematopoiesis, thermogenesis, reproduction, angiogenesis, and more importantly immune homeostasis. As a cytokine, leptin can affect thymic homeostasis and the secretion of acute-phase reactants such as interleukin-1 (IL-1) and tumor-necrosis factor-alpha (TNF-α). Leptin links nutritional status and proinflammatory T helper 1 (Th1) immune responses and the decrease in leptin plasma concentration during food deprivation leads to impaired immune function. Conversely, elevated circulating leptin levels in obesity appear to contribute to the low-grade inflammatory background which makes obese individuals more susceptible to increased risk of developing cardiovascular diseases, diabetes, or degenerative disease including autoimmunity and cancer. In this review, we provide an overview of recent advances on the role of leptin in the pathogenesis of several autoimmune disorders that may be of particular relevance in the modulation of the autoimmune attack through metabolic-based therapeutic approaches.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Emerging role of leptin in rheumatoid arthritis

Numerous studies have suggested the importance of leptin against autoimmune diseases such as systemic lupus erythematosus (SLE), multiple sclerosis (MS) and psoriasis. To summarize our current understanding of the role of leptin in inflammatory responses and rheumatoid arthritis (RA), a systematic review was conducted to assess the discrepancy of leptin in RA and its effect on immunity according to different studies. Recently, emerging data have indicated that leptin is involved in the pathological function of RA, which is common in autoimmune disorders. This review discusses the possible consequences of leptin levels in RA. Blocking the key signal pathways of leptin and inhibiting the leptin activity-like leptin antagonist may be a promising way for potential therapeutic treatment of RA at risk of detrimental effects. However, leptin was increased in patients with RA and may also regulate joint damage. Thus, more understanding of the mechanism of leptin in RA would be advantageous in the future.

Pathogenesis and treatment of atherosclerosis in lupus

The prevalence of atherosclerosis (ATH) is higher in patients with systemic lupus erythematosus (SLE) and occurs at an earlier age. The lupus-related factors that account for this increased risk are likely numerous and related to the factors described in this article. Identifying of at-risk subjects and increasing the understanding of pathogenesis of ATH in SLE is critical for improving the quality of care and improving mortality in this vulnerable population.

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.

Relationship between serum leptin level and disease activity in patients with systemic sclerosis

To determine the relationship between serum leptin levels and disease activity in systemic sclerosis (SSc). A total of 60 subjects (30 controls and 30 patients) were included. The inflammatory markers and leptin levels were evaluated and body mass index (BMI) was measured for both groups. The assessment of the skin involvement was performed based on the modified Rodnan skin score (mRSS). Disease activity was evaluated according to the Valentini scleroderma disease activity index. There was a significant difference between the patient and control groups in terms of BMI (p < 0.05); however there was no difference with regards to age and gender (p > 0.05). Valentini scores and mRSS were determined to be significantly higher in active patients (n = 14) than in inactive patients (n = 16) (p < 0.05). No significant difference was determined between groups in terms of leptin levels (p > 0.05). However, leptin levels were significantly lower in active patients than in inactive patients (p < 0.05). We found a significant positive correlation between serum leptin and BMI (p < 0.05), and leptin and serum C3 levels (p < 0.05); no relationship was detected between leptin and other parameters. Leptin can be used as an activity marker in SSc. Further studies, including larger series, should be carried out to clarify this relationship.

Leptin promotes lupus T-cell autoimmunity

In systemic lupus erythematosus (SLE), the impairment in apoptosis can facilitate the initiation and maintenance of autoimmune responses to self antigens. Here we show that the adipocytokine leptin, which is abnormally elevated in SLE, promotes the survival and proliferation of autoreactive T-cells in mice with an autoreactive T-cell repertoire, including (NZB x NZW)F1 lupus-prone mice. This ability of leptin to promote lupus T-cell autoimmunity suggests the possibility of a therapeutic targeting of leptin in SLE.

Decreased serum level of soluble-leptin-receptor in patients with systemic lupus erythematosus

BACKGROUND

There is some evidence suggesting that leptin and its negative regulator, soluble-leptinreceptor (SLR) may be able to influence inflammatory and autoimmune processes.

METHODS

In this study, several variables including socio-demographics, health-related habits, depression score, serum molecules and blood parameters besides the SLR level were evaluated in patients with SLE (SLE-patients) and healthy controls.

RESULTS

The patients had significantly lower SLR level and higher depression score than the controls and both of these variables have a significant association with the occurrence of disease in logistic regression model. Moreover, the results of Pearson correlation analysis showed that patients' SLR level was negatively correlated with their weights and BDI scores.

CONCLUSION

For the first time, this study indicated a lower level of SLR in SLE-patients and suggested that lower concentrations of SLR in these patients may be implicated in the pathogenesis of SLE.

Role of adipokines in atherosclerosis: interferences with cardiovascular complications in rheumatic diseases

Patients with rheumatic diseases have an increased risk of mortality by cardiovascular events. In fact, several rheumatic diseases such as rheumatoid arthritis, osteoarthritis, systemic lupus erythematosus, and ankylosing spondylitis are associated with a higher prevalence of cardiovascular diseases (CVDs). Although traditional cardiovascular risk factors have been involved in the pathogenesis of cardiovascular diseases in rheumatic patients, these alterations do not completely explain the enhanced cardiovascular risk in this population. Obesity and its pathologic alteration of fat mass and dysfunction, due to an altered pattern of secretion of proinflammatory adipokines, could be one of the links between cardiovascular and rheumatic diseases. Indeed, the incidence of CVDs is augmented in obese individuals with rheumatic disorders. Thus, in this paper we explore in detail the relationships among adipokines, rheumatic diseases, and cardiovascular complications by giving to the reader a holistic vision and several suggestions for future perspectives and potential clinical implications.

The role of adipokines in connective tissue diseases

Objective

To discuss the relationship between adipokines and connective tissue diseases, by putting special emphasis on the potential role of leptin, adiponectin, resistin, and other adipose tissue products in the pathogenesis of rheumatoid arthritis and systemic lupus erythematosus and on possible application of adipokine-targeted therapy in the treatment of these disorders with emphasis on the recent findings.

Methods

PubMed literature search complemented by review of bibliographies listed in identified articles.

Results

Most of the data presented by different research groups showed changed levels of leptin, adiponectin, and resistin and occasionally also other adpokines in rheumatoid arthritis and systemic lupus erythematosus. The relationship between the remaining connective tissue diseases and adipokines is less documented.

Conclusions

Plasma levels of adipokines might tell us too little about their role in connective tissue disorders, whereas adipokine effects on synovial tissues might differ from their known metabolic or cardiovascular effects, which implies that some re-appraisal of adipokines role may need to take place. It still remains obscure whether the observed disturbances in various adipokine systems in subjects with connective tissue diseases contribute to their development or only reflect the presence or activity of inflammatory process, which itself is induced by other pro-inflammatory factors.

Resistin is associated with the inflammation process in patients with systemic autoimmune diseases undergoing glucocorticoid therapy: comparison with leptin and adiponectin

OBJECTIVES

We investigated the role of adipokines in patients with systemic autoimmune diseases who received glucocorticoid therapy.

METHODS

Fifty-two patients with systemic autoimmune diseases who had started glucocorticoid therapy were prospectively enrolled. One hundred forty healthy persons were also studied as controls. Serum levels of 3 adipokines [resistin, leptin, and high molecular weight (HMW)-adiponectin] were measured with enzyme-linked immunosorbent assay kits before and at weekly intervals for 4 weeks during glucocorticoid therapy. The effects of lipopolysaccharide and dexamethasone on adipokine expression in human peripheral blood mononuclear cells (PBMCs) were also examined.

RESULTS

The serum resistin level was significantly higher in patients than in controls before glucocorticoid therapy, and it decreased after glucocorticoid therapy. Consistent with these results, dexamethasone inhibited lipopolysaccharide-induced upregulation of resistin expression in PBMCs in vitro. Serum leptin and HMW-adiponectin levels were lower in the patients than in the controls at baseline, and both adipokine levels were increased after glucocorticoid therapy. There was a significant correlation between serum resistin and high-sensitivity C-reactive protein. However, there was no association between serum adipokines and intima-media thickness.

CONCLUSION

Resistin may be associated with the inflammatory process but not atherosclerosis in patients with systemic autoimmune diseases.

Systemic lupus erythematosus and cardiovascular disease: prediction and potential for therapeutic intervention

Patients with systemic lupus erythematosus have a significantly increased risk of cardiovascular events due to atherosclerosis. Traditional cardiac risk factors cannot fully explain this increased risk. Recent evidence strongly suggests that atherosclerotic plaque is largely driven by inflammation and an active immunological response, in contrast to the long-held belief that plaque is a passive accumulation of lipids in the arterial wall. Current approaches to the prevention of atherosclerosis in systemic lupus erythematosus involve targeting modifiable cardiac risk factors. Future preventive strategies may include therapies that counteract the immunologic responses that lead to plaque formation.

High plasma leptin levels confer increased risk of atherosclerosis in women with systemic lupus erythematosus, and are associated with inflammatory oxidised lipids

Background

Patients with systemic lupus erythematosus (SLE) are at increased risk of atherosclerosis, even after accounting for traditional risk factors. High levels of leptin and low levels of adiponectin are associated with both atherosclerosis and immunomodulatory functions in the general population.

Objective

To examine the association between these adipokines and subclinical atherosclerosis in SLE, and also with other known inflammatory biomarkers of atherosclerosis.

Methods

Carotid ultrasonography was performed in 250 women with SLE and 122 controls. Plasma leptin and adiponectin levels were measured. Lipoprotein a (Lp(a)), oxidised phospholipids on apoB100 (OxPL/apoB100), paraoxonase, apoA-1 and inflammatory high-density lipoprotein (HDL) function were also assessed.

Results

Leptin levels were significantly higher in patients with SLE than in controls (23.7±28.0 vs 13.3±12.9 ng/ml, p<0.001). Leptin was also higher in the 43 patients with SLE with plaque than without plaque (36.4±32.3 vs 20.9±26.4 ng/ml, p=0.002). After multivariate analysis, the only significant factors associated with plaque in SLE were leptin levels in the highest quartile (≥29.5 ng/ml) (OR=2.8, p=0.03), proinflammatory HDL (piHDL) (OR=12.8, p<0.001), age (OR=1.1, p<0.001), tobacco use (OR=7.7, p=0.03) and hypertension (OR=3.0, p=0.01). Adiponectin levels were not significantly associated with plaque in our cohort. A significant correlation between leptin and piHDL function (p<0.001), Lp(a) (p=0.01) and OxPL/apoB100 (p=0.02) was also present.

Conclusions

High leptin levels greatly increase the risk of subclinical atherosclerosis in SLE, and are also associated with an increase in inflammatory biomarkers of atherosclerosis such as piHDL, Lp(a) and OxPL/apoB100. High leptin levels may help to identify patients with SLE at risk of atherosclerosis.

Leptin in immuno-rheumatological diseases

Leptin is one of the most important hormones secreted by adipocytes, with a variety of physiological roles related to the control of metabolism and energy homeostasis. Since its discovery in 1994, leptin has attracted increasing interest in the scientific community for its pleiotropic actions. One of these functions is the relationship between nutritional status and immune competence. It structurally resembles proinflammatory cytokines, such as IL-6 and IL-12. The cytokine-like structural characteristic of leptin is implicative of its function in regulating immune responses. The role of leptin in regulating immune responses has been assessed in vitro as well as in clinical studies. It has been shown that disease conditions of reduced leptin production are associated with increased infection susceptibility. Conversely, immune-mediated disorders, such as autoimmune diseases, are associated with the increased secretion of leptin and the production of proinflammatory pathogenic cytokines. In this paper, we review the most recent advances of the role of leptin in immune-rheumatological diseases, and we discuss whether strategies aimed at modifying leptin levels could represent innovative and therapeutic tools for autoimmune disorders.

Elevated adiponectin serum levels in women with systemic autoimmune diseases

Adipose tissue produces a wide range of proteins that may influence the immune system. In this study, we assessed the serum levels of leptin, adiponectin, and ghrelin, in association with the measurements of body composition, in 15 female patients with various autoimmune diseases (systemic lupus erythematosus, primary Sjögren's syndrome, sarcoidosis, mixed connective tissue disease, vasculitis, CREST syndrome, and polymyositis) and in 15 healthy female controls. There were no statistically significant differences between the patients and controls with regard to serum leptin, serum ghrelin, global fat mass, adiposity, and fat mass in the android or gynoid regions, whereas serum adiponectin levels were higher in patients than controls (16.3 ± 1.6 μg/mL versus 9.7 ± 0.6 μg/mL; P = .01). As adiponectin is known to exhibit potent anti-inflammatory properties, a high adiponectinemia in patients with systemic autoimmune disease may mitigate the inflammatory response. However, the precise consequences of these elevated serum adiponectin levels on the metabolic syndrome development and atherosclerotic cardiovascular risk in this patient population still needs to be determined.

Leptin and ghrelin in Korean systemic lupus erythematosus

Elevated serum leptin levels have been described in patients with systemic lupus erythematosus (SLE), however these studies have provided no information regarding the ghrelin levels. We investigated the clinical significance of serum leptin and ghrelin levels in SLE. The leptin levels of SLE patients were higher than those of normal healthy controls, while the ghrelin levels of the SLE were lower. In addition, the ghrelin levels were significantly lower in SLE patients with arthritis and hematologic disorder. Taken together, these findings suggest that leptin and ghrelin play a role in clinical manifestations observed in SLE. Lupus (2010) 19, 170—174.

Serum adipokine levels in patients with systemic lupus erythematosus

In patients with systemic lupus erythematosus (SLE) metabolic alterations are often observed, which may be due to either the disease, the genetic background or the treatment. We studied the serum levels of the adipokines leptin, adiponectin, resistin, visfatin and ghrelin in patients with SLE and controls. Leptin levels were lower and adiponectin, ghrelin and visfatin levels were higher in the patients. No significant differences were encountered for resistin. The values of adipokines were independent of treatment, even after correction for body mass index. Inverse correlations were found among leptin and adiponectin, ghrelin and visfatin. We conclude that adipokines are involved in the metabolic imbalance of patients with SLE.

The peroxisome proliferator-activated receptor gamma agonist rosiglitazone ameliorates murine lupus by induction of adiponectin

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease for which current therapy is suboptimal. SLE is characterized by autoantibody production, with renal disease and premature atherosclerosis being common and severe manifestations causing appreciable morbidity and mortality. Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists are widely used in the treatment of diabetes mellitus for their insulin-sensitizing properties, but also have immunomodulatory effects. In this report, we show that the PPARgamma agonist rosiglitazone reduces autoantibody production, renal disease, and atherosclerosis in mouse models of SLE. The beneficial effect of rosiglitazone on SLE manifestations depends on the induction of adiponectin, because rosiglitazone has no effect on autoantibody production or renal disease in lupus mice that lack adiponectin. In addition, lupus mice that lack adiponectin develop more severe disease than adiponectin-sufficient lupus mice, indicating that endogenous adiponectin is involved in regulating disease activity. Furthermore, administration of exogenous adiponectin ameliorates disease. These experiments suggest that PPARgamma agonists may be useful agents for the treatment of SLE. They also demonstrate that induction of adiponectin is a major mechanism underlying the immunomodulatory effects of PPARgamma agonists.