Association between the neutrophil-to-lymphocyte ratio, a new marker of systemic inflammation, and restless legs syndrome

Association between inflammatory cytokines and disease severity in restless legs syndrome

BACKGROUND

This study aims to evaluate serum cytokine levels in individuals with primary Restless Legs Syndrome (RLS) and analyze their correlation with RLS symptom severity, sleep disturbances, anxiety, and depression.

METHODS

A case-control study was conducted involving 87 primary RLS patients and 100 healthy individuals undergoing health check-ups. Serum cytokine levels were assessed, and RLS severity was evaluated using the International Restless Legs Syndrome Study Group (IRLSSG) rating scale. Additionally, the Pittsburgh Sleep Quality Index (PSQI), 24-item Hamilton Depression Rating Scale (HAMD24), and 14-item Hamilton Anxiety Rating Scale (HAMA14) were utilized to assess symptom severity, sleep disturbances, and emotional states in RLS patients.

RESULTS

Serum cytokine levels, including IL-6 and TNF-α, were significantly higher in RLS patients compared to controls (P < 0.05). Adjustment for disease duration, sex, age, BMI, SBP, and DBP revealed an independent association between serum IL-6 and RLS (OR = 1.46; 95% CI = 1.02-1.93; P = 0.003). Linear regression analysis demonstrated a significant correlation between IL-6 levels and IRLS scores (β = 0.123, P = 0.008).

CONCLUSION

Elevated circulating levels of inflammatory cytokines in RLS patients suggest a potential role of inflammation in the pathogenesis of primary RLS. Additionally, serum cytokine levels correlate closely with disease severity.

Bibliometric analyses of publications in the field of restless legs syndrome

PURPOSE

Restless Legs Syndrome (RLS) is a chronic neurological disorder and the incidence of RLS is a more common disease than known is accepted. This study was performed to identify and analyze the characteristics of RLS-related articles published from 2001 to 2020 using bibliometric analyses.

METHODS

RLS-related articles published from 2001 to 2020 were retrieved from the Web of Science Core Collection database with predefined search terms. VOSviewer software was used to visualize various bibliographic coupling networks on data. The top 10 lists (about organizations, papers, journals, most commonly cited articles, authors, countries, and keywords) extracted from 2001 to 2020 were also analyzed.

RESULTS

A total of 2311 articles were included and the total number of publications from 2001 to 2020 was increased by 5.02-fold. The highest number of RLS publications (n = 171) since 2001 was observed in 2020. The United States is contributed the highest number of RLS-related publications (34.53%). The top productive journal was Sleep Medicine and the most prominent organization was Johns Hopkins University. In the list of top 10 authors, Allen RP was the first author.

CONCLUSIONS

This study is the first bibliometric analysis that provides a general perspective on the RLS from 2001 to 2020 and may be useful as a guide for further research in this field.

Restless legs syndrome in patients with psoriasis: association with inflammation and sleep quality

BACKGROUND

We aimed to evaluate if psoriasis associated with restless legs syndrome (RLS) due to its close relationship with metabolic disorders.

METHODS

This was a cross-sectional study in which the relationship between RLS and psoriasis was evaluated. Seventy consecutive psoriasis patients and 70 controls without any skin disorder were included in this study. Data including age, gender, body weight, height, and Psoriasis Area Severity Index (PASI) scores were recorded. Diagnosis of RLS was established using International RLS Study Group (IRLSSG) diagnostic criteria. International RLS Rating Scale (IRLSRS) was used to evaluate the severity of symptoms. Each participant completed forms of the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), and the Dermatology Life Quality Index (DLQI).

RESULTS

The RLS frequency in patients with psoriasis was 18.6% vs. 5.7% in the control group (P = 0.018). In psoriasis patients, BMI, DLQI, IRLSRS, hemoglobin, ferritin, CRP, and uric acid levels were significantly higher than those of the controls. In psoriasis patients with RLS, PASI, DLQI, PSQI, IRLSRS scores, CRP level, and BMI were significantly higher, and hemoglobin level was significantly lower relative to the psoriasis patients without RLS. PASI score was the sole independent associate of RLS presence in psoriasis patients.

CONCLUSION

Restless legs syndrome was significantly more common in psoriasis patients, and the presence of RLS was associated with significantly more severe psoriasis, more severe systemic inflammation, lower serum hemoglobin values, worse quality of life, and sleep quality.

Inflammatory factors and restless legs syndrome: A systematic review and meta-analysis

The possible role of inflammatory factors in the pathogenesis of restless legs syndrome (RLS) is not well understood. Because several inflammatory diseases have shown an association with the risk for RLS, the measurement of serum/plasma levels of inflammatory factors has been a matter of a scarce number of studies. We performed a systematic review and a meta-analysis to assess the possible association of serum/plasma levels of inflammatory markers with the risk for RLS. Our results showed a significant trend towards higher serum/plasma C reactive protein (CRP) levels and higher neutrophil-to-lymphocyte (NLR) ratio in patients diagnosed with RLS than in controls, although statistical significance disappeared after applying the random-effects model. Further studies are needed to confirm the suggested possible role of inflammatory factors in the pathogenesis of RLS.

LAG3/CD4 Genes Variants and the Risk for Restless Legs Syndrome

According to several studies, inflammatory factors could be related to the pathogenesis of idiopathic restless legs syndrome (RLS). In addition, RLS and Parkinson's disease (PD) have shown a possible relationship, and recent studies have shown an association between CD4 rs1922452 and CD4 rs951818 single nucleotide variants (SNVs) and the risk for PD. For these reasons, we investigated the possible association between common variants in the LAG3/CD4 genes (which encoded proteins involved in inflammatory and autoimmune responses) and the risk for RLS in a Caucasian Spanish population. We assessed the frequencies of CD4 rs1922452, CD4 rs951818, and LAG3 rs870849 genotypes and allelic variants in 285 patients with idiopathic RLS and 350 healthy controls using a specific TaqMan-based qPCR assay. We also analyzed the possible influence of the genotypes' frequencies on several variables, including age at onset of RLS, gender, family history of RLS, and response to drugs commonly used in the treatment of RLS. We found a lack of association between the frequencies of genotypes and allelic variants of the 3 SNVs studied and the risk of RLS, and a weak though significant association between the CD4 rs1922452 GG genotype and an older age at onset of RLS. With the exception of this association, our findings suggest that common SNVs in the CD4/LAG3 genes are not associated with the risk of developing idiopathic RLS in Caucasian Spanish people.

Chronic inflammation markers and cytokine-specific autoantibodies in Danish blood donors with restless legs syndrome

Restless Legs Syndrome (RLS) is a neurological sensorimotor disorder negatively impacting sufferers’ quality of sleep and health-related quality of life. The pathophysiology of RLS is poorly understood and research focusing on the link between RLS and inflammation has been limited. Our study aimed to investigate whether chronic inflammation markers C-reactive protein (CRP) and soluble urokinase-type plasminogen activator receptor (suPAR), as well plasma levels of five different cytokine-specific autoantibodies (c-aAb), i.e. modulators of inflammation, associate with RLS in otherwise healthy individuals. CRP, suPAR and c-aAb were measured in plasma samples of participants from the Danish Blood Donor Study in 2010. Returning donors between 2015 and 2018 completed the validated Cambridge-Hopkins RLS-questionnaire for RLS assessment, resulting in datasets with RLS assessment and values for CRP (N = 3564), suPAR (N = 2546) and c-aAb (N = 1478). We performed logistic regression models using the CRP, suPAR or c-aAb as the independent variable and RLS status as the dependent variable, adjusted for appropriate covariates. Our study indicates that a high concentration of CRP is associated with RLS, while an increased probability of experiencing frequent RLS symptoms in those with an elevated plasma suPAR level appears to be mediated through lifestyle factors. We additionally report that a high titer of autoantibodies specific against the cytokine interferon-alpha was associated with RLS. Our results support the existence of links between systemic inflammation and RLS, though further RLS studies on CRP, suPAR and c-aAb in larger cohorts are warranted to confirm our findings and further reveal the hitherto underexplored links between RLS and inflammation.

Diagnostic Value of the Neutrophil-to-Lymphocyte Ratio (NLR) and Platelet-to-Lymphocyte Ratio (PLR) in Various Respiratory Diseases: A Retrospective Analysis

The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte (PLR) ratio are two extensively used inflammatory markers that have been proved very useful in evaluating inflammation in several diseases. The present article aimed to investigate if they have any value in distinguishing among various respiratory disorders. One hundred and forty-five patients with coronavirus disease 2019 (COVID-19), 219 patients with different chronic respiratory diseases (interstitial lung disease, obstructive sleep apnea(OSA)-chronic obstructive pulmonary disease (COPD) overlap syndrome, bronchiectasis) and 161 healthy individuals as a control group were included in the study. While neither NLR nor PLR had any power in differentiating between various diseases, PLR was found to be significant but poor as a diagnostic test when the control group was compared with the OSA-COPD group. NLR was found to be significant but poor as a diagnostic test when we compared the control group with all three groups (separately): the OSA-COPD group; interstitial lung disease group, and bronchiectasis group. NLR and PLR had poor power to discriminate between various respiratory diseases and cannot be used in making the differential diagnosis.

Investigating the inflammation marker neutrophil-to-lymphocyte ratio in Danish blood donors with restless legs syndrome

Background

Restless Legs Syndrome (RLS) is a neurological sensorimotor disorder that occurs in the evening and night, thereby impacting quality of sleep in sufferers. The pathophysiology of RLS is poorly understood but inflammation has been proposed as possibly being involved. The neutrophil-to-lymphocyte ratio (NLR) can be used as an inflammation marker but results from small studies have been inconclusive in determining whether NLR is associated with RLS. We aimed to assess whether an association between NLR and RLS exists in a large cohort of healthy individuals.

Methods

Neutrophils and lymphocytes were measured in blood samples of 13,055 individuals from the Danish Blood Donor Study, all of whom completed the validated Cambridge-Hopkins RLS-questionnaire for RLS assessment.

Results

In the sample, 661 individuals were determined as current RLS cases (5.1%). A higher proportion of individuals with RLS were females (62.5% vs 47.5%; P<0.001) and RLS cases were older than controls (P<0.001), but no differences in body mass index (BMI), smoking or alcohol consumption were found between the two groups. An increased NLR was observed in RLS cases compared to controls (median NLR: 1.80 vs 1.72; P = 0.033). In an unadjusted logistic regression model, increased NLR was associated with RLS (OR = 1.10 per NLR unit increase [95%CI:1.01–1.20]; P = 0.032); however, the association was not significant in multivariate models adjusting for sex and age (P = 0.094) or sex, age, alcohol consumption, smoking status and BMI (P = 0.107).

Conclusion

We found no association between RLS and NLR among Danish blood donors after adjusting for sex, age, alcohol consumption, smoking status and BMI. Further studies are needed to determine whether inflammation is a risk factor for RLS.

No association between plasma hepcidin levels and restless legs syndrome - results from the Danish Blood Donor Study

BACKGROUND

Restless Legs Syndrome (RLS) is a neurological sensorimotor disorder that occurs in the evening and night, thereby often impacting quality of sleep in sufferers. The aetiology of RLS is not completely understood although iron dysregulation has been suggested as a likely pathway. The relationship between RLS and the iron regulatory protein hepcidin has not been studied in large cohorts. We aimed to assess whether an association between plasma hepcidin variation and RLS exists in a large cohort of healthy individuals.

METHODS

Plasma hepcidin levels were measured in 9708 Danish blood donors from the Danish Blood Donor Study all of whom correctly completed the validated Cambridge-Hopkins RLS-questionnaire for RLS assessment.

RESULTS

A total of 466 blood donors were determined as current RLS cases in the sample (4.8%). RLS cases had a significantly higher proportion of females (56.7% vs 46.7%; P < 0.001) and were older (median age [IQR] 40.6 years vs 38.0 years; P = 0.010) than controls. RLS cases were also more frequent smokers (P = 0.004). No significant differences were found in body mass index (BMI), alcohol consumption, time of donation and donation history between cases and controls. No difference in plasma hepcidin levels was observed between RLS cases and controls (median concentration [IQR]: 10.5 ng/ml [6.3-16.4] in RLS cases vs 10.5 ng/ml [6.0-16.5] in controls). Using a logistic regression model, we found that hepcidin levels were not associated with RLS after adjusting for age, sex, alcohol consumption, smoking status, donation time and donation history (OR = 1.00 [0.99-1.02] per 1 ng/ml increase of hepcidin; P = 0.429).

CONCLUSION

Our study in Danish blood donors did not find an association between RLS and plasma hepcidin levels. Our findings suggest that plasma hepcidin's role as a potential diagnostic biomarker of RLS is inadequate.

Restless legs syndrome in pediatric onset multiple sclerosis

BACKGROUND

Restless legs syndrome/Willis-Ekbom disease (RLS/WED) was shown to have a high prevalence among adults with multiple sclerosis (MS).

OBJECTIVE

We aimed to investigate the prevalence of RLS/WED and to define the disease characteristics in young patients with pediatric onset multiple sclerosis (POMS) METHOD: 50 patients with POMS were questioned for the presence of RLS/WED. The demographic, clinical and laboratory data were compared between POMS patients with and without RLS/WED, including the total number of clinical and/or radiological MS attacks, interval between first two attacks, EDSS, number of the hyperintense and/or contrast-enhancing lesions, localization of demyelinating lesions, IgG index in cerebrospinal fluid, oligoclonal band, serum ferritin, C-reactive protein, ratio of neutrophil to lymphocyte count, and 25‑hydroxy vitaminD.

RESULTS

Eleven patients (22%) had RLS/WED - mostly of moderate in severity (54.5%). Mean EDSS score was significantly higher in POMS patients with RLS/WED than those without (p = 0.003). The Ig G index was almost two times higher in POMS patients with RLS/WED, but it failed to reach to the statistically significant level (p = 0.073).

CONCLUSION

Our study demonstrated high prevalence of RLS/WED in young patients with POMS. Higher EDSS scores in patients with POMS and RLS/WED indicates disease-related factors in the emergence of RLS/WED.

Searching for Novel Candidate Biomarkers of RLS in Blood by Proteomic Analysis

PURPOSE

We performed comparative proteomic analyses of blood of patients with RLS and healthy individuals aiming to identify potential biomarker and therapeutic target candidate for RLS.

PATIENTS AND METHODS

Blood serum samples from 12 patients with a clinical diagnosis of RLS (8 females and 4 males, with a mean age of 68.52 years) and 10 healthy controls (5 females and 5 males, with a mean age of 67.61 years) underwent proteomic profiling by liquid chromatography coupled with tandem mass spectrometry. Pathway analysis incorporating protein-protein interaction networks was carried out to identify pathological processes linked to the differentially expressed proteins.

RESULTS

We quantified 272 proteins in patients with RLS and healthy controls, of which 243 were shared. Five proteins - apolipoprotein C-II, leucine-rich alpha-2-glycoprotein 1, FLJ92374, extracellular matrix protein 1, and FLJ93143 - were substantially increased in RLS patients, whereas nine proteins - vitamin D-binding protein, FLJ78071, alpha-1-antitrypsin, CD5 antigen-like, haptoglobin, fibrinogen alpha chain, complement factor H-related protein 1, platelet factor 4, and plasma protease C1 inhibitor - were decreased. Bioinformatics analyses revealed that these proteins were linked to 1) inflammatory and immune response, and complement activation, 2) brain-related development, cell aging, and memory disorders, 3) pregnancy and associated complications, 4) myocardial infarction, and 5) reactive oxygen species generation and subsequent diabetes mellitus.

CONCLUSION

Our findings shed light on the multifactorial nature of RLS and identified a set of circulating proteins that may have clinical importance as biomarkers and therapeutic targets.

Changes in Hepcidin Serum Levels Correlate with Clinical Improvement in Idiopathic Restless Legs Syndrome Patients

BACKGROUND

Restless legs syndrome (RLS) is a common sensory motor neurological disorder that is related to iron-dopamine dysregulation and immune system alteration. We aimed to assess the effects of serum hepcidin, an iron-regulating hormone, in drug-naive RLS patients compared to healthy controls and to evaluate its role in helping to predict clinical improvement after treatment with dopamine agonist.

METHODS

Nonanemic and drug-naive RLS patients (n = 18) and healthy controls (n = 15) were enrolled. The serum hepcidin and iron-related values in the serum were measured upon the first visit in both groups and 12 weeks later after dopaminergic treatment in 12 patients. Information about sociodemographic characteristics, sleep-related profiles, mood and anxiety was obtained upon the first visit in all participants as well as after treatment in RLS patients.

RESULTS

Serum hepcidin levels exhibited no significant differences between patients with drug-naïve RLS and healthy controls at diagnosis (7.1 ± 2.4 vs. 7.0 ± 3.2 ng/mL, p = 0.357). Decreased hepcidin levels were significantly associated with decreased RLS severity (β = 0.002, 95% CI = 0.00-0.00, p = 0.005) and improved quality of life (β = 0.002, 95% CI = 0.00-7.01, p = 0.044) in a dose-dependent manner after 12 weeks of treatment with a dopamine agonist. This association was independent of age, sex, inflammatory markers, sleep quality, insomnia, daytime sleepiness, depression and anxiety.

CONCLUSIONS

This study demonstrates the role of hepcidin in evaluating the positive therapeutic response in RLS.

Bioinformatic analysis of proteomic data for iron, inflammation, and hypoxic pathways in restless legs syndrome

OBJECTIVE/BACKGROUND

We performed bioinformatic analysis of proteomic data to identify the biomarkers of restless legs syndrome (RLS) and provide insights into the putative pathomechanisms, including iron deficiency, inflammation, and hypoxic pathways.

PATIENTS/METHODS

Patients with drug-naïve idiopathic RLS were recruited at a university hospital from June 2017 to February 2018. Serum samples from patients with RLS (n = 7) and healthy sex- and age-matched controls (n = 6) were evaluated by proteomic analysis. For differentially expressed proteins (DEPs) in patients with RLS, compared to those in controls, the expression profiles and protein-protein interaction (PPI) network were characterized between dysregulated proteins and extracted proteins involved in iron deficiency, hypoxia, and inflammation responses using the String database (http://string-DB.org). The PPI network was visualized by Cytoscape ver. 3. 7. 1. Statistical analyses of the validation Western blot assays were performed using a Student's t-test.

RESULTS

Interactome network analysis revealed a relationship among the eight proteins, their associated genes, and 150, 47, and 11 proteins related to iron deficiency, inflammation, and hypoxic pathways, respectively. All DEPs were well associated with inflammation, and complement 3, complement C4A, alpha-2 HS glycoprotein, and alpha-2 macroglobulin precursor were found to be in hub positions of networks involved in PPIs including iron deficiency, hypoxia pathway, and inflammation. C3 and C4A were verified using western blotting.

CONCLUSIONS

We identified key molecules that represent the selected cellular pathways as protein biomarkers by PPI network analysis. Changes in inflammation can mediate or affect the pathomechanism of RLS and can thus act as systemic biomarkers.

Use of antidepressants and risks of restless legs syndrome in patients with irritable bowel syndrome: A population-based cohort study

Previous research has suggested an association between antidepressants use and clinical restless legs syndrome (RLS) in patients, but there has never been a single study investigating the risk of RLS in irritable bowel syndrome (IBS) patients treated with antidepressants. Hence, we aimed to explore the association between IBS and RLS and to examine the risk of RLS in IBS patients treated with antidepressants. With the use of the National Health Insurance Research Database of Taiwan, 27,437 adults aged ≥ 20 years with newly diagnosed IBS (ICD-9-CM Code 564.1) and gender- and age-matched 54,874 controls without IBS were enrolled between 2000 and 2012. All patients were followed-up until RLS diagnosis, withdrawal from the National Health Insurance program, or end of 2013. We used the Cox proportional hazards model to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of RLS. RLS was more prevalent in IBS patients than in the non-IBS group (7.57 versus 3.36 per 10,000 person-years), with an increased risk of RLS (adjusted HR [aHR], 1.91; 95% CI, 1.52-2.40). Multivariate Cox proportional hazards analysis identified older age (age, 51-65 years; aHR, 1.67; 95% CI, 1.09-2.56; and age > 65; aHR, 1.59; 95% CI, 1.02-2.48), hypothyroidism (aHR, 4.24; 95% CI, 1.92-9.37), CAD (aHR, 1.70; 95% CI, 1.17-2.48), and depression (aHR, 3.15; 95% CI, 2.14-4.64) as independent RLS risk factors in IBS patients. In addition, the male SSRIs users were associated with significantly higher risk of RLS (aHR, 3.05 95% CI, 1.34-6.92). Our study showed that the IBS group has higher risk of RLS. Moreover, SSRIs use may increase the risk of RLS in male IBS patients.

Serum C-reactive protein/albumin ratio and restless legs syndrome

OBJECTIVES

Our study aimed to assess the variation in serum C-reactive protein/albumin ratio (CAR), a biomarker of peripheral inflammation and oxidative stress, in patients with restless legs syndrome (RLS).

METHODS

The study included a total of 380 individuals including 197 with RLS diagnosis. RLS diagnosis was determined according to the "International Restless Legs Syndrome Study Group" questionnaire. Disease severity was assessed according to the "International Restless Legs Syndrome Study Group Severity Scale''.

RESULTS

The mean age of patients with restless legs syndrome was 52.5 ± 12.7 years, while the mean age in the control group was 50.8 ± 11.2, with no statistically significant difference found (p = 0.156). The hemoglobin, iron and ferritin levels in the patient group were lower than in the control group (p < 0.001; p < 0.01; p < 0.001), with total iron binding capacity levels higher than the control group (p < 0.001). The mean ferritin in the RLS group (49.8 ± 51.2) was lower than the control group (76.9 ± 44.7). In patients, the c-reactive protein, albumin and c-reactive protein/albumin ratio were found to be 0.21 ± 0.18, 4.43 ± 0.31 and 0.07 ± 0.05, respectively. When compared with the control group, the patient group had high c-reactive protein (CRP), CAR and low albumin levels (p < 0.001). Among patients with "very severe" disease severity, ferritin levels were found to be lower than those with "moderate" disease severity. Additionally, patients with "very severe" disease had albumin levels which were significantly low compared to those with "mild" disease severity (p < 0.05).

CONCLUSION

Our study supports the hypothesis that serum albumin level, ferritin, CRP, and CAR may be associated with restless legs syndrome.