Alpha defensins 1, 2, and 3: potential roles in dyslipidemia and vascular dysfunction in humans

The Diagnostic Value of Human Neutrophilic Peptides 1-3 in Acute Pediatric Febrile Illness

Background: It is prudent to develop biomarkers that enhance the differentiation between viral and bacterial infection in order to support expeditious and judicious antimicrobial implementation in emergency department admissions. Human neutrophilic peptides 1-3 (HNP1-3) are the major neutrophilic peptides with potent antimicrobial activity. Methods: We tested the performance of the plasma HNP1-3 test in a prospective observational cohort of children admitted to the emergency department for fever. We validated this test with traditionally used biomarkers and final diagnoses. An expert panel reviewed the patient's data and gave a final diagnosis. The final diagnosis was classified as definite, probable, or possible. Results: A total of 111 children (98 with fever and 13 control) were recruited: 55% male, mean age 6.3 years. Plasma HNP1-3 levels were higher with bacterial infections: 10,428 (5789-14,866) vs. 7352 (3762-10,672) pg/mL, p = 0.007. HNP1-3 were negatively correlated with age: r = -0.207, p = 0.029. Of the different categorical variables tested, only c-reactive protein (CRP) (≥42.3 mg/dL), neutrophil count (≥10.2), and age (odds ratio = 1.185, p = 0.013 and 95%CI = 1.037-1.354) had significant diagnostic capability for bacterial disease prediction. Conclusions: Due to its low diagnostic value in febrile patients, the HNP1-3 value is not currently recommended to support pathogen differentiation in children in an emergency setting. Further studies are needed to support its clinical use.

Mechanisms and regulation of defensins in host defense

As a family of cationic host defense peptides, defensins are mainly synthesized by Paneth cells, neutrophils, and epithelial cells, contributing to host defense. Their biological functions in innate immunity, as well as their structure and activity relationships, along with their mechanisms of action and therapeutic potential, have been of great interest in recent years. To highlight the key research into the role of defensins in human and animal health, we first describe their research history, structural features, evolution, and antimicrobial mechanisms. Next, we cover the role of defensins in immune homeostasis, chemotaxis, mucosal barrier function, gut microbiota regulation, intestinal development and regulation of cell death. Further, we discuss their clinical relevance and therapeutic potential in various diseases, including infectious disease, inflammatory bowel disease, diabetes and obesity, chronic inflammatory lung disease, periodontitis and cancer. Finally, we summarize the current knowledge regarding the nutrient-dependent regulation of defensins, including fatty acids, amino acids, microelements, plant extracts, and probiotics, while considering the clinical application of such regulation. Together, the review summarizes the various biological functions, mechanism of actions and potential clinical significance of defensins, along with the challenges in developing defensins-based therapy, thus providing crucial insights into their biology and potential clinical utility.

Molecular and cellular mechanisms of inflammation in atherosclerosis

Atherosclerosis and its complications are a major cause of morbidity and mortality worldwide in spite of the improved medical and invasive treatment in terms of revascularization. Atherosclerosis is a dynamic, multi-step process in which inflammation is a ubiquitous component participating in the initiation, development, and entanglements of the atherosclerotic plaque. After activation, the immune system, either native or acquired, is part of the atherosclerotic dynamics enhancing the pro-atherogenic function of immune or non-immune cells, such as endothelial cells, smooth muscle cells, or platelets, through mediators such as cytokines or directly by cell-to-cell interaction. Cytokines are molecules secreted by the activated cells mentioned above that mediate the inflammatory component of atherosclerosis whose function is to stimulate the immune cells and the production of further cytokines. This review provides insights of the cell axis activation and specific mechanisms and pathways through which inflammation actuates atherosclerosis.

A subset of low density granulocytes is associated with vascular calcification in chronic kidney disease patients

Inflammation is central to chronic kidney disease (CKD) pathogenesis and vascular outcomes, but the exact players remain unidentified. Since low density granulocytes (LDGs) are emerging mediators in inflammatory conditions, we aimed to evaluate whether LDGs may be altered in CKD and related to clinical outcomes as biomarkers. To his end, LDGs subsets were measured in peripheral blood by flow cytometry and confocal microscopy in 33 CKD patients undergoing peritoneal dialysis and 15 healthy controls (HC). Analyses were replicated in an additional cohort. DEF3 (marker of early granulopoiesis) gene expression on PBMCs was quantified by qPCR. Total CD15+ LDGs and both CD14lowCD16+ and CD14-CD16- subsets were expanded in CKD. The relative frequency of the CD14-CD16- subpopulation was higher among the CD15+ pool in CKD. This alteration was stable over-time. The increased CD14-CD16-CD15+ paralleled Kauppila scores and DEF3 expression, whereas no association was found with CD14lowCD16+ CD15+. Both subsets differed in their CD11b, CD10, CD35, CD31, CD62L, IFNAR1 and CD68 expression, FSC/SSC features and nuclear morphology, pointing to different origins and maturation status. In conclusion, LDGs were expanded in CKD showing a skewed distribution towards a CD14-CD16-CD15+ enrichment, in association with vascular calcification. DEF3 expression in PBMC can be a marker of LDG expansion.

Body composition does not affect serum levels of cathelicidin LL-37 in elderly women with unipolar depression

OBJECTIVES

Antimicrobial peptides are components of the innate immune system. Cathelicidin LL-37 plays an important role in antimicrobial defense, exerts proinflammatory effect and strongly affects the immune system functioning. Our recent study revealed that serum concentration of LL-37 is increased in elderly women with depression. The aim of this study is to evaluate serum LL-37 levels in elderly women with depression and to compare them with non-depressed elderly women, matched for anthropometric and body composition parameters.

METHODS

Forty women with unipolar depression and 23 non-depressed women (age ≥60 years) were included into the study. Anthropometric measurements and biochemical analyzes were performed. Concentration of LL-37 in serum was assessed using ELISA method. Body composition was measured using two methods: bioimpedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA).

RESULTS

There was a statistically significant difference (p =.038) in serum LL-37 level between patients with depression (3.55 ± 6.57 ng/mL) and control subjects (2.01 ± 3.88 ng/mL). Apart from visceral adipose tissue mass (%) in the depression group, we found no associations between serum LL-37 and analyzed anthropometric or body composition parameters.

CONCLUSIONS

Results of this study indicate that with the exception of visceral adipose tissue, LL-37 serum levels are not affected by anthropometric or body composition parameters. The association between visceral adipose tissue and LL-37 may indicate that visceral fat could be responsible for the increased LL-37 production.

The correlation between plasma human neutrophil peptide 1-3 levels and severity of coronary artery disease

Introduction

Inflammation plays a key role in atherosclerosis, and discovering new biomarkers of inflammation is becoming important in order to uncover the pathogenesis of atherosclerotic coronary artery disease (CAD). Recent studies have focused on polymorphonuclear neutrophils. It has been suggested that human neutrophil peptide 1-3 (HNP1-3) is proatherogenic. In this study, we aimed to investigate the associations between plasma HNP1-3 levels and the severity of atherosclerosis via a generally accepted scoring system.

Material and methods

This cross-sectional, observational study included 107 consecutive patients suffering from stable angina pectoris and undergoing coronary angiography (CAG). Patients were divided into two groups according to the Gensini scoring (GS) system evaluating disease severity. Group 1 was composed of mild CAD patients with GS < 20 and group 2 consisted of severe CAD patients with GS ≥ 20. Plasma HNP1-3 levels were assessed by the ELISA method.

Results

The mean HNP1-3 levels were found to be lower in group 1 than group 2 (134.7 ng/ml vs. 147.5 ng/ml). HNP1-3 levels were significantly higher in the severe CAD group than the mild CAD group according to GS (p < 0.001). The results of multivariate logistic regression analysis revealed that only age > 62 years and HNP1-3 > 134 ng/ml were independent predictors of the severity of CAD after adjusting for gender, smoking, hypertension, hyperlipidemia, diabetes, family history of CAD and white blood cell count. In predicting the severity of CAD, the sensitivity and specificity of HNP1-3 were 83.9% (p < 0.001) and 58.8% (p < 0.001), respectively.

Conclusions

This study revealed that the plasma levels of HNP1-3 were significantly higher in severe CAD than mild CAD.

PPBP and DEFA1/DEFA3 genes in hyperlipidaemia as feasible synergistic inflammatory biomarkers for coronary heart disease

BACKGROUND

Coronary heart disease (CHD) is an important complication of atherosclerosis. Biomarkers, which associate with CHD development, are potential to predict CHD risk. To determine whether genes showing altered expression in hyperlipidaemia (H) and coronary heart disease (CHD) patients compared with controls could be CHD risk biomarkers.

METHODS

Control, H, and CHD groups represented atherosclerosis to CHD development. Gene profiling was investigated in peripheral blood mononuclear cells using DNA microarrays. Eight selected genes expressed only in H and CHD groups were validated by real-time quantitative reverse transcription PCR and plasma protein determination.

RESULTS

α-defensin (DEFA1/DEFA3), pro-platelet basic protein (PPBP), and beta and alpha2 hemoglobin mRNA expression was significantly increased in H and CHD groups compared with controls, but only plasma PPBP and α-defensin proteins were correspondingly increased.

CONCLUSION

PPBP and DEFA1/DEFA3 could be potential CHD biomarkers in Thai hyperlipidaemia patients.

α-Defensins and bacterial/permeability-increasing protein as new markers of childhood obesity

OBJECTIVES

The aim of this paper is to test whether α-defensins and bacterial/permeability-increasing protein were related to obesity and cardiovascular risk factors in prepubertal children.

METHODS

Plasma α-defensins and bacterial/permeability-increasing protein, body mass index (BMI), waist circumference, systolic blood pressure (SBP), carotid intima media thickness (cIMT), HOMA-IR and HMW-adiponectin were assessed.

RESULTS

In a cross-sectional study (N = 250), higher α-defensins concentrations were positively associated with BMI, waist, SBP, cIMT, HOMA-IR and negative correlated with HMW-adiponectin (all between r = 0.191 and r = 0.377, p ≤ 0.01 and p ≤ 0.0001). Conversely, plasma bacterial/permeability-increasing protein concentrations presented inversed associated with the same parameters (all between r = -0.124 and r = -0.329; p ≤ 0.05 and p ≤ 0.0001). In a longitudinal study (N = 91), α-defensins at age 7 were associated with BMI (β = 0.189, p = 0.002; model R²  = 0.847) and waist (β = 0.241, pthinsp;= 0.001; model R²  = 0.754) at age 10.

CONCLUSIONS

α-Defensins and bacterial/permeability-increasing protein may be the markers of childhood obesity. Increased concentrations of α-defensins may predict BMI and abdominal fat deposition in children.

Effects of precalving body condition and prepartum feeding level on gene expression in circulating neutrophils

Extensive metabolic, physiological, and immunological changes are associated with calving and the onset of lactation. As a result, cows transitioning between pregnancy and lactation are at a greater risk of metabolic and infectious diseases. The ability of neutrophils to mount an effective immune response to an infection is critical for its resolution, and increasing evidence indicates that precalving nutrition affects postpartum neutrophil function. The objectives of the current study were to investigate the effect of 2 precalving body condition scores (BCS; 4 vs. 5 on a 10-point scale) and 2 levels of feeding (75 vs. 125% of estimated maintenance requirements) on gene expression in circulating neutrophils. We isolated RNA from the neutrophils of cows (n = 45) at 5 time points over the transition period: precalving (-1 wk), day of calving (d 0), and postcalving at wk 1, 2, and 4. Quantitative reverse transcriptase PCR with custom-designed primer pairs and Roche Universal Probe Library (Roche, Basel, Switzerland) chemistry, combined with microfluidics integrated fluidic circuit chips (96.96 dynamic array), were used to quantify the expression of 78 genes involved in neutrophil function and 18 endogenous control genes. Statistical significance between time points was determined using repeated measures ANOVA with Tukey-Kramer multiple-testing correction to determine treatment effects among weeks. Precalving BCS altered the inflammatory state of neutrophils, with significant increases in overall gene expression of antimicrobial peptides (BNBD4 and DEFB10) and the anti-inflammatory cytokine IL10, and significantly decreased expression of proinflammatory cytokine IL23A in thinner cows (BCS 4) compared with cows calving at BCS 5. Feeding level had a time-dependent effect on gene expression; for example, increased expression of genes involved in leukotriene synthesis (PLA2G4A and ALOX5AP) occurred only at 1 wk postcalving in cows overfed (125% of requirements) precalving compared with those offered 75% of maintenance requirements. Results indicate that precalving body condition and changes in prepartum energy lead to altered gene expression of circulating neutrophils, highlighting the importance of transition cow nutrition for peripartum health.

Human Neutrophil Peptide 1 Limits Hypercholesterolemia-induced Atherosclerosis by Increasing Hepatic LDL Clearance

Increases in plasma LDL-cholesterol have unequivocally been established as a causal risk factor for atherosclerosis. Hence, strategies for lowering of LDL-cholesterol may have immediate therapeutic relevance. Here we study the role of human neutrophil peptide 1 (HNP1) in a mouse model of atherosclerosis and identify its potent atheroprotective effect both upon transgenic overexpression and therapeutic delivery. The effect was found to be due to a reduction of plasma LDL-cholesterol. Mechanistically, HNP1 binds to apolipoproteins enriched in LDL. This interaction facilitates clearance of LDL particles in the liver via LDL receptor. Thus, we here identify a non-redundant mechanism by which HNP1 allows for reduction of LDL-cholesterol, a process that may be therapeutically instructed to lower cardiovascular risk.

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Mice with transgenic expression of human neutrophil peptide 1 (HNP1) exhibit lower plasma VLDL/LDL levels and smaller atherosclerotic lesion sizes.

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Repetitive HNP1 delivery is atheroprotective by reducing hypercholesterolemia.

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HNP1 binds to apolipoproteins in LDL and facilitates LDL clearance in the liver involving LDL receptor.

Increased plasma lipid levels (i.e. hypercholesterolemia) are a primary risk factor for atherosclerosis, the pathology underlying myocardial infarction and stroke. Here we show that human neutrophil peptide 1 (HNP1, also known as α-defensin), an antimicrobial protein typically released from activated neutrophils, binds to apolipoproteins within plasma lipoproteins and facilitates the clearance of plasma lipids in the liver. As a consequence, repeated injection of hypercholesterolemic mice with HNP1 reduces atherosclerotic lesion formation. Thus, this study provides an innovative strategy to reduce hypercholesterolemia and hence a way to potentially reduce cardiovascular risk.

Upregulated expression of human alpha-defensins 1, 2 and 3 in hypercholesteremia and its relationship with serum lipid levels

Human alpha-defensins are natural antimicrobial peptides of neutrophils evolved in host defense reactions and circulating nonstressed alpha-defensins may be associated with serum lipid levels. The aim of this work was to examine whether the expression of alpha-defensins 1, 2 and 3 genes are changed and whether this changes are reversed following treatment in patients with hypercholesteremia. A total of 40 individuals of hypercholesteremia group were studied, compared with 40 individuals of normal control group. Protein levels and gene expression levels of alpha-defensins 1, 2 and 3 were significantly higher in patients with hypercholesteremia compared with subjects in normal control group. In patients with hypercholesteremia, protein levels of alpha-defensins 1, 2 and 3 correlated positively with the levels of total cholesterol and low-density lipoprotein cholesterol. Protein levels and gene expression levels of alpha-defensins 1, 2 and 3 were decreased significantly after a treatment with atorvastatin calcium 20mg daily compared with the patients before the treatment. Our results suggest that the expression of alpha-defensins 1, 2 and 3 genes is involved in dyslipidemia in patients with hypercholesteremia.

Common genetic variants of surfactant protein-D (SP-D) are associated with type 2 diabetes

Context

Surfactant protein-D (SP-D) is a primordial component of the innate immune system intrinsically linked to metabolic pathways. We aimed to study the association of single nucleotide polymorphisms (SNPs) affecting SP-D with insulin resistance and type 2 diabetes (T2D).

Research Design and Methods

We evaluated a common genetic variant located in the SP-D coding region (rs721917, Met³¹Thr) in a sample of T2D patients and non-diabetic controls (n = 2,711). In a subset of subjects (n = 1,062), this SNP was analyzed in association with circulating SP-D concentrations, insulin resistance, and T2D. This SNP and others were also screened in the publicly available Genome Wide Association (GWA) database of the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC).

Results

We found the significant association of rs721917 with circulating SP-D, parameters of insulin resistance and T2D. Indeed, G carriers showed decreased circulating SP-D (p = 0.004), decreased fasting glucose (p = 0.0002), glycated hemoglobin (p = 0.0005), and 33% (p = 0.002) lower prevalence of T2D, estimated under a dominant model, especially among women. Interestingly, these differences remained significant after controlling for origin, age, gender, and circulating SP-D. Moreover, this SNP and others within the SP-D genomic region (i.e. rs10887344) were significantly associated with quantitative measures of glucose homeostasis, insulin sensitivity, and T2D, according to GWAS datasets from MAGIC.

Conclusions

SP-D gene polymorphisms are associated with insulin resistance and T2D. These associations are independent of circulating SP-D concentrations.

Targeting the association of calgranulin B (S100A9) with insulin resistance and type 2 diabetes

Calgranulin B (S100A9) was recognized as a candidate type 2 diabetes (T2D) gene in the genomic profiling of muscle from a rodent model of T2D and identifying the human orthologs of genes localized in T2D susceptibility regions. Circulating and S100A9 expressions in muscle and adipose tissue, isolated fat cells, and mouse models were evaluated. A common 5'-upstream single-nucleotide polymorphism (SNP; rs3014866) for S100A9 was analyzed, as well as the effects of weight loss and treatments in vitro with recombinant S100A9. S100a9 expression was increased in muscle of diabetic mice (1.6-fold, p = 0.002), and in muscle from subjects with impaired glucose tolerance (∼4-fold, p = 0.028; n = 34). The rs3014866 SNP was associated with circulating S100A9 and the risk of T2D, having TT carriers at 28 % (p = 0.03) lower risk (n = 1,450). Indeed, increased circulating S100A9 (∼4-fold, p = 0.03; n = 206) and subcutaneous (2-fold, p = 0.01) and omental (1.4-fold, p = 0.04) S100A9 gene expressions (n = 83) in TT carriers run in parallel to decreased fasting glucose and glycated hemoglobin. Accordingly, metformin led to increased S100A9 mRNA in ex vivo-treated adipose tissue explants (n = 5/treatment). Otherwise, obese subjects showed a compensatory increase in circulating and S100A9 expressions in adipose (n = 126), as further demonstrated by decreased levels after diet- (-34 %, p = 0.002; n = 20) and surgery-induced (-58 %, p = 0.02; n = 8) weight loss. Lipopolysaccharide led to increased S100A9 in adipose from mice (n = 5/treatment) while recombinant S100A9 downregulated inflammation in adipocytes (n = 3/treatment). Current findings support the strategy of testing differentially expressed genes in mice and human orthologs associated with T2D. The increased S100A9 reported for obesity and insulin resistance may be envisioned as a compensatory mechanism for inflammation.

Serum and urinary concentrations of calprotectin as markers of insulin resistance and type 2 diabetes

OBJECTIVE

Increased circulating calprotectin has been reported in obese subjects but not in association with measures of insulin resistance and type 2 diabetes (T2D). The main aim of this study was to determine whether calprotectins in plasma and urine are associated with insulin resistance.

DESIGN

We performed both cross-sectional and longitudinal (diet-induced weight loss) studies.

METHODS

Circulating calprotectin concentrations (ELISA), other inflammatory markers, homeostasis model assessment of insulin resistance (HOMA-IR), and parameters of glucose and lipid metabolism were evaluated in 298 subjects (185 with normal (NGT) and 62 with impaired (IGT) glucose tolerance and 51 T2D subjects). Calprotectin was also evaluated in urine samples from 71 participants (50 NGT and 21 subjects with IGT). Insulin sensitivity (S(I), Minimal Model) was determined in a subset of 156 subjects, and the effects of weight loss were investigated in an independent cohort of obese subjects (n=19).

RESULTS

Circulating calprotectin was significantly increased in IGT-T2D (independently of BMI) and positively associated with HOMA-IR, obesity measures, inflammatory markers, and parameters of glucose and lipid metabolism. Similar findings were reported for calprotectin concentrations in urine. In the subset of subjects, the association of calprotectin with S(I) was independent of BMI and age. In fact, S(I) together with C-reactive protein contributed to 27.4% of calprotectin variance after controlling for age and blood neutrophils count. Otherwise, weight loss led to decreased circulating calprotectin in parallel to fasting glucose and HOMA-IR.

CONCLUSION

These findings suggest that circulating and urinary concentrations of calprotectin are linked to chronic low-grade inflammation and insulin resistance beyond obesity.

Mirror extreme BMI phenotypes associated with gene dosage at the chromosome 16p11.2 locus

Both obesity and being underweight have been associated with increased mortality. Underweight, defined as a body mass index (BMI) ≤ 18.5 kg per m(2) in adults and ≤ -2 standard deviations from the mean in children, is the main sign of a series of heterogeneous clinical conditions including failure to thrive, feeding and eating disorder and/or anorexia nervosa. In contrast to obesity, few genetic variants underlying these clinical conditions have been reported. We previously showed that hemizygosity of a ∼600-kilobase (kb) region on the short arm of chromosome 16 causes a highly penetrant form of obesity that is often associated with hyperphagia and intellectual disabilities. Here we show that the corresponding reciprocal duplication is associated with being underweight. We identified 138 duplication carriers (including 132 novel cases and 108 unrelated carriers) from individuals clinically referred for developmental or intellectual disabilities (DD/ID) or psychiatric disorders, or recruited from population-based cohorts. These carriers show significantly reduced postnatal weight and BMI. Half of the boys younger than five years are underweight with a probable diagnosis of failure to thrive, whereas adult duplication carriers have an 8.3-fold increased risk of being clinically underweight. We observe a trend towards increased severity in males, as well as a depletion of male carriers among non-medically ascertained cases. These features are associated with an unusually high frequency of selective and restrictive eating behaviours and a significant reduction in head circumference. Each of the observed phenotypes is the converse of one reported in carriers of deletions at this locus. The phenotypes correlate with changes in transcript levels for genes mapping within the duplication but not in flanking regions. The reciprocal impact of these 16p11.2 copy-number variants indicates that severe obesity and being underweight could have mirror aetiologies, possibly through contrasting effects on energy balance.

Circulating omentin as a novel biomarker of endothelial dysfunction

Omentin is a novel soluble lectin expressed mainly in the stromal-vascular cells from visceral adipose tissue with vasodilator effect in isolated blood vessels. To gain insight in the relationship between obesity and cardiovascular risk factors, we aimed to explore the interaction among circulating omentin, metabolic parameters, and endothelial function. Circulating omentin (enzyme-linked immunosorbent assay) was studied in 248 white men (148 with normal glucose tolerance (NGT) and 100 with impaired glucose tolerance (IGT)). Insulin sensitivity was measured using the frequently sampled intravenous glucose tolerance test. Vascular reactivity was measured by high-resolution ultrasound of the brachial artery. Circulating omentin concentration was significantly increased in lean compared with overweight and obese subjects (53.7 ± 16.9 vs. 45.2 ± 16.8 and vs. 40.1 ± 15.5 ng/ml, P < 0.0001). Circulating omentin concentration correlated with age, BMI, waist-to-hip ratio (WHR), percentage of fat mass, systolic and diastolic blood pressure, endothelium-dependent and independent vasodilation (EDV and EIV), C-reactive protein, and interleukin-6 (IL-6). In IGT subjects, circulating omentin concentration also correlated with insulin sensitivity, although this association did not remain significant after controlling for BMI. In a multiple linear regression analysis, circulating omentin concentration (P = 0.01), systolic blood pressure (P = 0.04), and BMI (P = 0.04) contributed independently to EDV after controlling for age and C-reactive protein in IGT subjects. In NGT subjects, only circulating omentin concentration (P = 0.01) was significantly associated with EDV. In conclusion, circulating omentin concentration could be a useful marker of endothelial function.

Association of human cathelicidin (hCAP-18/LL-37) gene expression with cardiovascular disease risk factors

BACKGROUND AND AIMS

Antimicrobial peptides (AMPs) are components of the innate immune system. In addition, evidence suggests that these peptides are associated with various inflammatory diseases. We examined whether expression of the cathelicidin LL-37 in peripheral blood mononuclear cells (PBMCs) is associated with cardiovascular risk factors.

METHODS AND RESULTS

A total of 90 men and 87 women selected from STANISLAS cohort were studied. Expression of LL-37 mRNA isolated from PBMCs of these subjects was quantified by quantitative RT-PCR. Anthropometric measurements and biochemical profiles were assessed for each individual. In women, LL-37 mRNA expression was significantly and positively correlated with body mass index (BMI) (p<or=0.001); waist circumference (WC) (p<or=0.01); systolic blood pressure (SBP) (p<or=0.05) and triglycerides (TG) level (p<or=0.05) and negatively with plasma levels of HDL-C (p<or=0.05). In men however, LL-37 was positively associated with waist to hip ratio (WHR) (p<or=0.05); SBP (p<or=0.001); TG (p<or=0.05); fasting glucose levels (p<or=0.01); alanine aminotransferase (ALT) activity (p<or=0.01); neutrophils counts (p<or=0.01) and negatively with lymphocyte counts (p<or=0.001); serum HDL-C (p<or=0.001) and apoA-I (p<or=0.05) levels. After adjustment for WC and BMI, multiple regression analysis showed that LL-37 remained significantly associated with SBP; HDL-C; fasting glucose level; ALT activity; neutrophil and lymphocyte counts (p<or=0.001 to p<or=0.05) in men.

CONCLUSION

Our results suggest that LL-37 gene expression may be closely associated with cardiovascular risk factors independently of BMI and WC. However, functional studies are required to confirm these data.

Human neutrophil peptides: a novel potential mediator of inflammatory cardiovascular diseases

The traditional view of atherosclerosis has recently been expanded from a predominantly lipid retentive disease to a coupling of inflammatory mechanisms and dyslipidemia. Studies have suggested a novel role for polymorphonuclear neutrophil (PMN)-dominant inflammation in the development of atherosclerosis. Human neutrophil peptides (HNPs), also known as alpha-defensins, are secreted and released from PMN granules upon activation and are conventionally involved in microbial killing. Current evidence suggests an important immunomodulative role for these peptides. HNP levels are markedly increased in inflammatory diseases including sepsis and acute coronary syndromes. They have been found within the intima of human atherosclerotic arteries, and their deposition in the skin correlates with the severity of coronary artery diseases. HNPs form complexes with LDL in solution and increase LDL binding to the endothelial surface. HNPs have also been shown to contribute to endothelial dysfunction, lipid metabolism disorder, and the inhibition of fibrinolysis. Given the emerging relationship between PMN-dominant inflammation and atherosclerosis, HNPs may serve as a link between them and as a biological marker and potential therapeutic target in cardiovascular diseases including coronary artery diseases and acute coronary syndromes.

Human neutrophil peptides upregulate expression of COX-2 and endothelin-1 by inducing oxidative stress

Polymorphonuclear leukocytes (PMNs) play an important role during inflammation in cardiovascular diseases. Human neutrophil peptides (HNPs) are released from PMN granules upon activation and are conventionally involved in microbial killing. Recent studies suggested that HNPs may be involved in the pathogenesis of vascular abnormality by modulating inflammatory responses and vascular tone. Since HNPs directly interact with endothelium upon release from PMNs in the circulation, we tested the hypothesis that the stimulation with HNPs of endothelial cells modulates the expression of vasoactive by-products through altering cyclooxygenase (COX) activity. When human umbilical vein endothelial cells were stimulated with purified HNPs, we observed a time- and dose-dependent increase in the expression of COX-2, whereas COX-1 levels remained unchanged. Despite an increased expression of COX-2 at the protein level, HNPs did not significantly enhance the COX-2 activity, thus the production of the prostaglandin PGI2. HNPs significantly induced the release of endothelin-1 (ET-1) as well as the formation of nitrotyrosine. The HNP-induced COX-2 and ET-1 production was attenuated by the treatment with the oxygen free radical scavenger N-acetyl-L-cysteine and the inhibitors of p38 MAPK and NF-kappaB, respectively. The angiontensin II pathway did not seem to be involved in the HNP-induced upregulation of COX-2 and ET-1 since the use of the angiotensin-converting enzyme inhibitor enalapril had no effect in this context. In conclusion, HNP may play an important role in the pathogenesis of inflammatory cardiovascular diseases by activating endothelial cells to produce vasoactive by-products as a result of oxidative stress.

Association of circulating lactoferrin concentration and 2 nonsynonymous LTF gene polymorphisms with dyslipidemia in men depends on glucose-tolerance status

BACKGROUND

Lactoferrin, an innate immune protein with antiinflammatory properties, shows considerable antiatherosclerosis activity in animal studies. We investigated the relationship between circulating lactoferrin, lactoferrin gene (LTF, lactotransferrin) polymorphisms, dyslipidemia, and vascular reactivity in the context of glucose-tolerance status in men.

METHODS

We evaluated 2 nonsynonymous LTF polymorphisms (rs1126477 and rs1126478) and measured circulating lactoferrin concentrations by ELISA under nonstressed conditions in healthy Caucasian men (n = 188) and male patients with an altered glucose tolerance (n = 202). We also studied the association of lactoferrin concentration with vascular reactivity via high-resolution ultrasound analysis of the brachial artery in a subsample of study participants.

RESULTS

Circulating lactoferrin concentration was inversely associated with fasting triglyceride concentration (r = -0.24; P = 0.001), body mass index (BMI) (r = -0.20; P = 0.007), waist-to-hip ratio (r = -0.35; P <0.001), and fasting glucose concentration (r = -0.18; P = 0.01), and directly correlated with HDL cholesterol concentration (r = 0.21; P = 0.004). Control AG heterozygotes for rs1126477 had significantly decreased fasting triglyceride concentrations (P = 0.001). Similarly, control individuals who were G carriers for rs1126478 had significantly lower fasting triglyceride concentrations (P = 0.044) and significantly higher HDL cholesterol concentrations (P = 0.028) than AA homozygotes. These associations remained significant after controlling for age, BMI, waist-to-hip ratio, fasting glucose concentration, smoking status, and alcohol intake. Circulating lactoferrin concentration was not significantly associated with endothelium-dependent vasodilatation (EDVD) in the individuals studied (n = 95); however, lactoferrin was positively associated with EDVD in obese participants with an altered glucose tolerance (r = 0.54; P = 0.04).

CONCLUSIONS

We have identified associations among LTF polymorphisms, circulating lactoferrin concentration, fasting triglyceride concentration, and vascular reactivity in humans.