Induction of neutrophil gelatinase-associated lipocalin in vascular injury via activation of nuclear factor-kappaB

Up-regulation of LCN2 in the anterior cingulate cortex contributes to neural injury-induced chronic pain

Chronic pain caused by disease or injury affects more than 30% of the general population. The molecular and cellular mechanisms underpinning the development of chronic pain remain unclear, resulting in scant effective treatments. Here, we combined electrophysiological recording, in vivo two-photon (2P) calcium imaging, fiber photometry, Western blotting, and chemogenetic methods to define a role for the secreted pro-inflammatory factor, Lipocalin-2 (LCN2), in chronic pain development in mice with spared nerve injury (SNI). We found that LCN2 expression was upregulated in the anterior cingulate cortex (ACC) at 14 days after SNI, resulting in hyperactivity of ACC glutamatergic neurons (ACC^Glu) and pain sensitization. By contrast, suppressing LCN2 protein levels in the ACC with viral constructs or exogenous application of neutralizing antibodies leads to significant attenuation of chronic pain by preventing ACC^Glu neuronal hyperactivity in SNI 2W mice. In addition, administering purified recombinant LCN2 protein in the ACC could induce pain sensitization by inducing ACC^Glu neuronal hyperactivity in naïve mice. This study provides a mechanism by which LCN2-mediated hyperactivity of ACC^Glu neurons contributes to pain sensitization, and reveals a new potential target for treating chronic pain.

Adzuki Bean MY59 Extract Reduces Insulin Resistance and Hepatic Steatosis in High-Fat-Fed Mice via the Downregulation of Lipocalin-2

Adzuki bean is well known as a potential functional food that improves metabolic complications from obesity and diabetes. Lipocalin-2 (LCN2) has been implicated to have an important role in obesity and diabetes. However, the protective roles of adzuki bean MY59 extract (ABE) on insulin resistance and hepatic steatosis are not fully understood. In the present study, we investigated the effects of ABE on LCN2 expression in high-fat diet (HFD)-fed mice. ABE reduced HFD-induced fat mass and improved insulin resistance. In addition to hepatic steatosis, HFD-fed mice showed many apoptotic cells and neutrophils in the epididymal fat pads. However, these findings were significantly reduced by ABE supplementation. In particular, we found that increased LCN2 proteins from serum, epididymal fat pads, and liver in HFD-fed mice are significantly reduced by ABE. Furthermore, ABE reduced increased heme oxygenase-1 and superoxide dismutase-1 expressions in adipose tissue and liver in HFD-fed mice. We found that hepatic nuclear factor-kappa B (NF-κB) p65 expression in HFD-fed mice was also reduced by ABE. Thus, these findings indicate that ABE feeding could improve insulin resistance and hepatic steatosis by decreasing LCN2-mediated inflammation and oxidative stress in HFD-fed mice.

The role of lipocalin 2 in brain injury and recovery after ischemic and hemorrhagic stroke

Ischemic and hemorrhagic stroke (including intracerebral hemorrhage, intraventricular hemorrhage, and subarachnoid hemorrhage) is the dominating cause of disability and death worldwide. Neuroinflammation, blood–brain barrier (BBB) disruption, neuronal death are the main pathological progress, which eventually causes brain injury. Increasing evidence indicated that lipocalin 2 (LCN2), a 25k-Da acute phase protein from the lipocalin superfamily, significantly increased immediately after the stroke and played a vital role in these events. Meanwhile, there exists a close relationship between LCN2 levels and the worse clinical outcome of patients with stroke. Further research revealed that LCN2 elimination is associated with reduced immune infiltrates, infarct volume, brain edema, BBB leakage, neuronal death, and neurological deficits. However, some studies revealed that LCN2 might also act as a beneficial factor in ischemic stroke. Nevertheless, the specific mechanism of LCN2 and its primary receptors (24p3R and megalin) involving in brain injury remains unclear. Therefore, it is necessary to investigate the mechanism of LCN2 induced brain damage after stroke. This review focuses on the role of LCN2 and its receptors in brain injury and aiming to find out possible therapeutic targets to reduce brain damage following stroke.

A targetable LIFR-NF-κB-LCN2 axis controls liver tumorigenesis and vulnerability to ferroptosis

The growing knowledge of ferroptosis has suggested the role and therapeutic potential of ferroptosis in cancer, but has not been translated into effective therapy. Liver cancer, primarily hepatocellular carcinoma (HCC), is highly lethal with limited treatment options. LIFR is frequently downregulated in HCC. Here, by studying hepatocyte-specific and inducible Lifr-knockout mice, we show that loss of Lifr promotes liver tumorigenesis and confers resistance to drug-induced ferroptosis. Mechanistically, loss of LIFR activates NF-κB signaling through SHP1, leading to upregulation of the iron-sequestering cytokine LCN2, which depletes iron and renders insensitivity to ferroptosis inducers. Notably, an LCN2-neutralizing antibody enhances the ferroptosis-inducing and anticancer effects of sorafenib on HCC patient-derived xenograft tumors with low LIFR expression and high LCN2 expression. Thus, anti-LCN2 therapy is a promising way to improve liver cancer treatment by targeting ferroptosis.

Neutrophil Gelatinase-Associated Lipocalin From Macrophages Plays a Critical Role in Renal Fibrosis Via the CCL5 (Chemokine Ligand 5)-Th2 Cells-IL4 (Interleukin 4) Pathway

NGAL (neutrophil gelatinase-associated lipocalin; or lipocalin 2, Lcn2) is a novel mineralocorticoid target in the cardiovascular system. We showed that Lcn2 gene invalidation protects against proteinuria and renal injury upon mineralocorticoid excess and we hypothesized that NGAL produced from macrophages promotes the expression of chemoattractant molecules involved these renal lesions. The role of NGAL was analyzed using myeloid-specific (MΦ KO NGAL) Lcn2 knockout mice challenged with uni-nephrectomy, aldosterone, and salt (NAS) for 6 weeks. The role of the CCL5 (chemokine ligand 5) and IL4 (interleukin 4) in kidney fibrosis was studied by administration of the CCL5 receptor antagonist maraviroc or by injections of an anti-IL4 neutralizing antibody. In CTL mice, NAS increased the renal expression of extracellular matrix proteins, such as collagen I, αSMA, and fibronectin associated with interstitial fibrosis which were blunted in MΦ KO NGAL mice. The expression of CCL5 was blunted in sorted macrophages from MΦ KO NGAL mice challenged by NAS and in macrophages obtained from KO NGAL mice and challenged ex vivo with aldosterone and salt. The pharmacological blockade of the CCL5 receptor reduced renal fibrosis and the CD4⁺ Th cell infiltration induced by NAS. Neutralization of IL4 in NAS mice blunted kidney fibrosis and the overexpression of profibrotic proteins, such as collagen I, αSMA, and fibronectin. In conclusion, NGAL produced by macrophages plays a critical role in renal fibrosis and modulates the CCL5/IL4 pathway in mice exposed to mineralocorticoid excess.

Mortality prediction of serum neutrophil gelatinase-associated lipocalin in patients requiring continuous renal replacement therapy

BACKGROUND/AIMS

We investigated whether serum neutrophil gelatinase-associated lipocalin (NGAL) can predict mortality in patients with acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT).

METHODS

This study enrolled 169 patients who underwent serum NGAL testing at CRRT initiation from June 2017 to January 2019. The predictive power of serum NGAL level for 28-day mortality was compared to the Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score and Sequential Organ Failure Assessment (SOFA) score via area under the receiver operating characteristic curve (AuROC) value.

RESULTS

There were 55 survivors and 114 non-survivors at 28 days post-CRRT initiation. Median serum NGAL level was significantly higher in the non-survivor group than in the survivor group (743.0 ng/mL vs. 504.0 ng/mL, p = 0.003). The AuROC value of serum NGAL level was 0.640, which was lower than APACHEII score and SOFA score values (0.767 and 0.715, respectively). However, in the low APACHE-II score group (< 27.5), AuROC value of serum NGAL was significantly increased (0.698), and it was an independent risk factor for 28 day-mortality (hazard ratio, 2.405; 95% confidence interval, 1.209 to 4.783; p = 0.012).

CONCLUSION

In patients with AKI requiring CRRT, serum NGAL levels may be useful for predicting short-term mortality in those with low APACHE-II scores.

Identification of plaque ruptures using a novel discriminative model comprising biomarkers in patients with acute coronary syndrome

Soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1), neutrophil gelatinase-associated lipocalin (NGAL), and matrix metalloproteinase-9 (MMP-9) are inflammatory biomarkers involved in plaque destabilization resulting in acute coronary syndrome (ACS). This study aimed to investigate the diagnostic value of a combination of biomarkers to discriminate plaque ruptures in the setting of ACS. Eighty-five ACS patients with optical coherence tomography (OCT) images of the culprit plaque were included and categorized into two groups: ACS with plaque rupture (Rupture group, n = 42) or without plaque rupture (Non-rupture group, n = 43) verified by OCT. A discriminative model of plaque rupture using several biomarkers was developed and validated. The Rupture group had higher white blood cell (WBC) counts and peak creatine kinase-myocardial band (CK-MB) levels (13.39 vs. 2.69 ng/mL, p = 0.0016). sLOX-1 (227.9 vs. 51.7 pg/mL, p < 0.0001) and MMP-9 (13.4 vs. 6.45 ng/mL, p = 0.0313) levels were significantly higher in the Rupture group, whereas NGAL showed a trend without statistical significance (59.03 vs. 53.80 ng/mL, p = 0.093). Receiver operating characteristic curves to differentiate Rupture group from Non-rupture group calculated the area under the curve for sLOX-1 (p < 0.001), MMP-9 (p = 0.0274), and NGAL (p = 0.0874) as 0.763, 0.645, and 0.609, respectively. A new combinatorial discriminative model including sLOX-1, MMP-9, WBC count, and the peak CK-MB level showed an area under the curve of 0.8431 (p < 0.001). With a cut-off point of 0.614, the sensitivity and specificity of plaque rupture were 62.2% and 97.6%, respectively. The new discriminative model using sLOX-1, MMP-9, WBC count, and peak CK-MB levels could better identify plaque rupture than each individual biomarker in ACS patients.

Subtilase cytotoxin induces a novel form of Lipocalin 2, which promotes Shiga-toxigenic Escherichia coli survival

Shiga-toxigenic Escherichia coli (STEC) infection causes severe bloody diarrhea, renal failure, and hemolytic uremic syndrome. Recent studies showed global increases in Locus for Enterocyte Effacement (LEE)-negative STEC infection. Some LEE-negative STEC produce Subtilase cytotoxin (SubAB), which cleaves endoplasmic reticulum (ER) chaperone protein BiP, inducing ER stress and apoptotic cell death. In this study, we report that SubAB induces expression of a novel form of Lipocalin-2 (LCN2), and describe its biological activity and effects on apoptotic cell death. SubAB induced expression of a novel LCN2, which was regulated by PRKR-like endoplasmic reticulum kinase via the C/EBP homologous protein pathway. SubAB-induced novel-sized LCN2 was not secreted into the culture supernatant. Increased intracellular iron level by addition of holo-transferrin or FeCl₃ suppressed SubAB-induced PARP cleavage. Normal-sized FLAG-tagged LCN2 suppressed STEC growth, but this effect was not seen in the presence of SubAB- or tunicamycin-induced unglycosylated FLAG-tagged LCN2. Our study demonstrates that SubAB-induced novel-sized LCN2 does not have anti-STEC activity, suggesting that SubAB plays a crucial role in the survival of LEE-negative STEC as well as inducing apoptosis of the host cells.

Relationships of adipocyte-fatty acid binding protein and lipocalin 2 with risk factors and chronic complications in type 2 diabetes and effects of fenofibrate: A fenofibrate Intervention and event lowering in diabetes sub-study

AIMS

To investigate determinants of circulating levels of adipocyte-fatty acid binding protein (A-FABP) and lipocalin-2 (LCN2), their relationships with cardiovascular disease (CVD) and microvascular events, and effects of fenofibrate in type 2 diabetes (T2D).

METHODS

A-FABP and LCN2 were quantified in baseline plasma from 2000 T2D adults in a Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial sub-study and correlates thereof determined. In a subset (n = 200) adipokines were also measured on-trial.

RESULTS

Female sex, older age, higher body mass index (BMI), HbA1c, insulin resistance index, triglycerides, plasma creatinine and homocysteine, shorter diabetes duration, and use of oral hypoglycaemic agents alone were independent determinants of higher A-FABP. Higher BMI, fibrinogen and homocysteine, Caucasian race, and lower fasting glucose, HDL-cholesterol, apolipoprotein A-II and estimated glomerular filtration rate were independent predictors of higher LCN2 levels. Baseline A-FABP and LCN2 levels were associated with multiple new CVD and microvascular events over 5-years, though significance was lost after risk factor adjustment. Fenofibrate increased A-FABP but did not change LCN2 levels.

CONCLUSIONS

Baseline plasma A-FABP and LCN2 levels were associated with concurrent CVD risk factors, and on-trial chronic complications, likely mediated via traditional risk factors. Fenofibrate increased A-FABP modestly but did not affect LCN2 levels.

CLINICAL TRIAL REGISTRATION

ISRCTN 64783481.

The Prognostic Utility of Plasma NGAL Levels in ST Segment Elevation in Myocardial Infarction Patients

Introduction

Plasma neutrophil gelatinase-associated lipocalin (NGAL) levels in acute myocardial infarction (AMI) patients are markedly higher. In addition, plasma NGAL levels were increased in patients with acute and chronic heart failure as a complication of myocardial infarction. In this study, we investigated whether there is a difference between the prognostic use of plasma NGAL levels in ST-elevation myocardial infarction (STEMI) patients with preserved and reduced left ventricular ejection fraction (LVEF).

Methods

235 consecutive STEMI patients were enrolled in the study. Patients were divided into groups according to LVEF. Plasma NGAL, troponin I, creatine kinase MB (CKMB), and C-reactive protein (CRP) were measured. Finally, the study population examined with 34 reduced LVEF and 34 preserved LVEF consisted of a total of 68 patients (12 females; mean age, 61.5 ± 14.7). All patients were followed up prospectively for 6 months. This study group was divided into two subgroups as the patients who died (n = 14) and survived (n = 34), and plasma NGAL levels of the groups were compared.

Results

The median of NGAL was 190.08 ng/ml. Age, troponin I, CKMB, CRP, glomerular filtration rate, and creatinine were higher in reduced LVEF groups. Plasma NGAL levels were also higher in reduced LVEF than in preserved LVEF, but statistically not significant (p=0.07). Plasma NGAL levels were significantly higher in death patients than in survived patients (p < 0.001). In ROC curve analysis, the level to detect isolated cardiovascular mortality with a sensitivity of 86% and a specificity of 77% was 190 ng/mL for NGAL.

Conclusion

Plasma NGAL levels can be used to predict cardiovascular mortality in STEMI patients.

Advanced glycation end-products increase lipocalin 2 expression in human oral epithelial cells

BACKGROUND AND OBJECTIVES

Diabetes mellitus (DM), a risk factor of periodontal diseases, exacerbates the pathological condition of periodontitis. A major factor for DM complications is advanced glycation end-products (AGEs) that accumulate in periodontal tissues and cause inflammatory events. Lipocalin 2 (LCN2) is an antimicrobial peptide and inflammation-related factor, and LCN2 levels increase in DM. In this study, the effects of AGEs and lipopolysaccharide of Porphyromonas gingivalis (P g-LPS) on LCN2 expression in human oral epithelial cells (TR146 cells) and the role of secreted LCN2 in periodontitis with DM were investigated.

MATERIAL AND METHODS

TR146 cells were cultured with AGEs (AGE2) and control BSA and cell viability was estimated, or with P g-LPS. Conditioned medium and cell lysates were prepared from cultures of epithelial cells and used for Western blotting and ELISA to analyze LCN2, RAGE, IL-6, MAPK, and NF-κB. RNA was isolated from AGE-treated TR146 cells and differentiated HL-60 (D-HL-60) cells and used for quantitative real-time PCR to examine the expression of LCN2 and interleukin-6 (IL-6) mRNAs. RAGE- and LCN2-siRNAs (siRAGE, siLCN2) were transfected into epithelial cells, and AGE-induced LCN2 expression was investigated. D-HL-60 cells were co-cultured with TR146 cells that were transfected with siLCN2 and treated with AGEs, and IL-6 mRNA expression in D-HL-60 cells and cell migration was investigated.

RESULTS

AGEs increased the expression levels of LCN2 and IL-6 in oral epithelial cells. siRAGE and a neutralizing antibody for RAGE inhibited AGE-induced LCN2 expression. AGEs stimulated the phosphorylation of ERK, p38, and NF-κB in epithelial cells, and their inhibitors suppressed AGE-induced LCN2 expression. In contrast, P g-LPS did not show a significant increase in LCN2 level in TR146 cells that expressed Toll-like receptor 2. In co-culture experiments, AGE-induced LCN2 inhibited IL-6 mRNA expression in D-HL-60 cells, and LCN2 knockdown in epithelial cells suppressed HL-60 cell migration.

CONCLUSION

These results suggested that AGEs increase LCN2 expression via RAGE, MAPK, and NF-κB signaling pathways in oral epithelial cells, and secreted LCN2 may influence the pathological condition of periodontitis with DM.

Lipocalin-2 exerts pro-atherosclerotic effects as evidenced by in vitro and in vivo experiments

Lipocalin-2 (LCN2), a multiple bioactive hormone particularly expressed in adipose tissue, neutrophils, and macrophages, is known to exhibit anti-microbial effect, increase inflammatory cytokine levels, and maintain glucose homeostasis. Serum LCN2 level is positively correlated with the severity of coronary artery disease. However, it still remains unknown whether LCN2 affects atherogenesis. We assessed the effects of LCN2 on the inflammatory response and monocyte adhesion in human umbilical vein endothelial cells (HUVECs), inflammatory phenotype and foam cell formation in THP1 monocyte-derived macrophages, and migration and proliferation of human aortic smooth muscle cells (HASMCs) in vitro and aortic lesions in Apoe^-/- mice in vivo. LCN2 and its receptor, low-density lipoprotein (LDL)-related protein-2, were expressed in THP1 monocytes, macrophages, HASMCs, and HUVECs. LCN2 significantly enhanced THP1 monocyte adhesion to HUVECs accompanied with upregulation of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin associated with nuclear factor-κB (NF-κB) upregulation in HUVECs. LCN2 significantly increased HUVEC proliferation and oxidized LDL-induced foam cell formation in THP1 monocyte-derived macrophages. LCN2 significantly increased the inflammatory M1 phenotype associated with NF-κB upregulation during differentiation of THP1 monocytes into macrophages. In HASMCs, LCN2 significantly promoted the migration and collagen-1 expression without inducing proliferation, which are associated with increased protein expression of phosphoinositide 3-kinase and phosphorylation of Akt, extracellular signal-regulated kinase, c-jun-N-terminal kinase, and NF-κB. Chronic LCN2 infusion into Apoe^-/- mice significantly accelerated the development of aortic atherosclerotic lesions, with increased intraplaque monocyte/macrophage infiltration and pentraxin-3 and collagen-1 expressions. Our results suggested that LCN2 accelerates the development of atherosclerosis. Thus, LCN2 could serve as a novel therapeutic target for atherosclerotic diseases.

Association Between Plasma Neutrophil Gelatinase-Associated Lipocalin and Cardiac Disease Hospitalizations and Deaths in Older Women

Background

Neutrophil gelatinase‐associated lipocalin (NGAL) or lipocalin 2 may promote atherosclerosis and plaque instability leading to increased risk of cardiac events. We investigated the relationships between plasma NGAL, cardiovascular disease biomarkers, and long‐term cardiac events.

Methods and Results

The study population consisted of 1131 ambulant older white women (mean age 75 years) without clinical coronary heart disease (CHD) and measures of plasma NGAL in the Perth Longitudinal Study of Ageing Women with 14.5‐year CHD and heart failure hospitalizations or death (events) captured using linked records. Over 14.5 years, 256 women had CHD events, while 118 had heart failure events. Per SD increase in log‐transformed NGAL there was a 35% to 37% increase in relative hazards for CHD and heart failure events in unadjusted analyses, which remained significant after adjustment for conventional risk factors for CHD events (hazard ratio 1.29, 95% CI 1.13–1.48, P<0.001) but not heart failure (P>0.05). Women in the highest 2 quartiles of NGAL had higher relative hazards for CHD events compared with women in the lowest quartile hazard ratio 1.61, 95% CI 1.08–2.39, P=0.019 and hazard ratio 1.97, 95% CI 1.33–3.93, P=0.001, respectively. These associations were independent of high‐sensitivity cardiac troponin I, homocysteine, and estimated renal function. NGAL correctly reclassified 1 in 4 women who sustained a CHD event up in risk and 1 in 10 women without CHD events down in risk.

Conclusions

NGAL was associated with increased risk of long‐term CHD events, independent of conventional risk factors and biomarkers. These findings provide mechanistic insight into the role of NGAL with cardiac events.

Adapted Moderate Training Exercise Decreases the Expression of Ngal in the Rat Kidney: An Immunohistochemical Study

Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of several injuries and is upregulated in inflammatory conditions. Vitamin D was shown to have anti-inflammatory effects and to increase after physical activity. This work aimed to assess, through immunohistochemistry, the effects of an adapted moderate training exercise (AMTE) on the expression of NGAL and vitamin D receptor (VDR) in the kidney and heart of rats. Sixteen rats were distributed into two groups: the sedentary control group and the experimental group, subjected to AMTE on the treadmill for 12 weeks. The results showed the basal expression of NGAL and VDR in both the heart and the kidney in sedentary rats; no differences in the expression of both NGAL and VDR in the heart; and a decreased NGAL and an increased VDR expression in the kidney of rats subjected to AMTE. These results suggest a possible protective role of AMTE on NGAL-associated injuries in the kidney, probably through the vitamin D signaling pathway. Our results represent an interesting preliminary data that may open new horizons in the management of NGAL-associated kidney injuries. However, further studies are needed to confirm these results and to comprehend the specific interaction between NGAL and VDR pathways in the kidney.

Cardiac expression of neutrophil gelatinase-associated lipocalin in a model of cancer cachexia-induced cardiomyopathy

AIMS

Cachexia is a severe consequence of cancer. Although cancer-induced heart atrophy leads to cardiac dysfunction and heart failure (HF), biomarkers for their diagnosis have not been identified. Neutrophil gelatinase-associated lipocalin (NGAL) is an aldosterone-responsive gene increased in HF. We studied NGAL and its association with aldosterone levels in a model of cancer cachexia-induced cardiomyopathy.

METHODS AND RESULTS

Rats were injected with Yoshida 108 AH-130 hepatoma cells to induce tumour. Cachectic rats were treated daily, for 16 days, with placebo or with 5 or 50 mg/kg/day of spironolactone. Cardiac function was analysed by echocardiography at baseline and at Day 11. Weight loss and atrophy of lean body and fat mass of cachectic rats were significantly attenuated by spironolactone. Cardiac dysfunction of tumour-bearing rats was improved by spironolactone. Plasma aldosterone was up-regulated from 337 ± 7 pg/mL in sham animals to 591 ± 31 pg/mL in the cachectic rats (P < 0.001 vs. sham). Treatment with 50 or 5 mg/kg/day of spironolactone reduced plasma aldosterone to 396 ± 22 and 391 ± 25 pg/mL (P < 0.01 vs. placebo). Plasma levels of NGAL were also increased in cachectic rats (1.462 ± 0.3603 μg/mL) than in controls (0.0936 ± 6 μg/mL, P < 0.001). Spironolactone treatment (50 mg/kg/day) significantly reduced cardiac mRNA and protein NGAL levels (P < 0.05 and P < 0.001 vs. placebo, respectively). NGAL mRNA and protein levels were overexpressed in cachectic animal hearts treated with placebo, compared with control (P < 0.05 and P < 0.01 vs. sham). Spironolactone treatment at 50 mg/kg/day reduced significantly cardiac NGAL (P < 0.05 and P < 0.001 vs. placebo).

CONCLUSIONS

Cancer cachexia induced increased levels of aldosterone and NGAL, contributing to worsening cardiac damage in cancer cachexia-induced cardiomyopathy. Spironolactone treatment may greatly attenuate cardiac dysfunction and lean mass atrophy associated with cancer cachexia.

Neutrophil gelatinase-associated lipocalin as a complementary biomarker for the asthma-chronic obstructive pulmonary disease overlap

Background

There is no standardized definition of the asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO). Although the blood eosinophil count is regarded as a biomarker for identifying ACO, it has no distinct value. This study aimed to measure plasma levels of neutrophil gelatinase-associated lipocalin (NGAL), a potential biomarker for distinguishing between ACO and non-ACO COPD.

Methods

We used the Korean cohort in the COPD in dusty area (CODA) study which included 137 subjects with COPD confirmed by spirometry. We defined ACO by a positive bronchodilator response (forced expiratory volume in 1 s, FEV₁ >12% and >200 mL from baseline) or based on a previous history of asthma. Plasma levels of NGAL were determined by enzyme immunoassay.

Results

Among the 137 subjects, 77 were ACO and 60 were non-ACO COPD. Overall, the plasma NGAL levels were 15.9±7.9 and 15.6±6.6 ng/mL for non-ACO and ACO subjects respectively, and not significantly different. However, NGAL levels were significantly higher in female subjects with ACO (17.0±6.4 vs. 11.1±4.5, P=0.01). In female subjects, NGAL levels showed a good predictive ability to discriminate between ACO and non-ACO COPD [area under the receiver operating characteristic curve (AUROC), 0.77]; the predictive ability was similar to that of the blood eosinophil count (AUROC, 0.79). There was a higher probability of discriminating ACO from non-ACO among subjects in the highest tertile of NGAL levels (odds ratio, 1.72; 95% confidence interval, 0.69-4.28; P for trend =0.01).

Conclusions

NGAL levels were significantly higher in ACO compared to non-ACO COPD in female subjects. After adjusting for gender as a confounding factor, the ability to distinguish ACO was better at higher levels of NGAL.

Early prediction of contrast-induced acute kidney injury by a "bedside" assessment of Neutrophil Gelatinase-Associated Lipocalin during elective percutaneous coronary interventions

Contrast-induced acute kidney injury (CI-AKI) is a serious complication during percutaneous coronary interventions (PCI). Currently, the diagnosis of CI-AKI relies on serum creatinine (SCr) that is however affected by several limitations potentially leading to delayed or missed diagnoses. In this study we examined the diagnostic accuracy of a “bedside” measurement of plasma Neutrophil Gelatinase-Associated Lipocalin (NGAL) in the early detection of CI-AKI in 97 patients undergoing elective PCI. The overall incidence of CI-AKI was 3%. A significant positive correlation was observed between 6-hours NGAL and post-PCI SCr (r = 0.339, p = 0.004) and a significant negative correlation between 6-hours NGAL and post-PCI CrCl (r = -0.303, p = 0.010). In patients with post-PCI SCr increase > 0.24 mg/dl (median SCr absolute increase), delta NGAL 0–6 hours and 6-hours NGAL values were higher compared with patients with SCr elevation below the defined threshold (p = 0.049 and p = 0.056). The ROC analysis showed that a 6 hours NGAL value > 96 ng/ml significantly predicted an absolute SCr increase > 0.24 mg/dl after contrast exposure with sensitivity of 53% and specificity of 74% (AUC 0.819, 95% CI: 0.656 to 0.983, p = 0.005). The use of bedside NGAL assessment may significantly hasten diagnosis and treatment of CI-AKI, with remarkable clinical prognostic consequences.

More than a simple biomarker: the role of NGAL in cardiovascular and renal diseases

Neutrophil gelatinase-associated lipocalin (NGAL) is a small circulating protein that is highly modulated in a wide variety of pathological situations, making it a useful biomarker of various disease states. It is one of the best markers of acute kidney injury, as it is rapidly released after tubular damage. However, a growing body of evidence highlights an important role for NGAL beyond that of a biomarker of renal dysfunction. Indeed, numerous studies have demonstrated a role for NGAL in both cardiovascular and renal diseases. In the present review, we summarize current knowledge concerning the involvement of NGAL in cardiovascular and renal diseases and discuss the various mechanisms underlying its pathological implications.

Lipocalin 2 Plays an Important Role in Regulating Inflammation in Retinal Degeneration

It has become increasingly important to understand how retinal inflammation is regulated because inflammation plays a role in retinal degenerative diseases. Lipocalin 2 (LCN2), an acute stress response protein with multiple innate immune functions, is increased in ATP-binding cassette subfamily A member 4 (Abca4) ^-/- retinol dehydrogenase 8 (Rdh8) ^-/- double-knockout mice, an animal model for Stargardt disease and age-related macular degeneration (AMD). To examine roles of LCN2 in retinal inflammation and degeneration, Lcn2^-/-Abca4^-/-Rdh8^-/- triple-knockout mice were generated. Exacerbated inflammation following light exposure was observed in Lcn2^-/-Abca4^-/-Rdh8^-/- mice as compared with Abca4^-/-Rdh8^-/- mice, with upregulation of proinflammatory genes and microglial activation. RNA array analyses revealed an increase in immune response molecules such as Ccl8, Ccl2, and Cxcl10 To further probe a possible regulatory role for LCN2 in retinal inflammation, we examined the in vitro effects of LCN2 on NF-κB signaling in human retinal pigmented epithelial (RPE) cells differentiated from induced pluripotent stem cells derived from healthy donors. We found that LCN2 induced expression of antioxidant enzymes heme oxygenase 1 and superoxide dismutase 2 in these RPE cells and could inhibit the cytotoxic effects of H₂O₂ and LPS. ELISA revealed increased LCN2 levels in plasma of patients with Stargardt disease, retinitis pigmentosa, and age-related macular degeneration as compared with healthy controls. Finally, overexpression of LCN2 in RPE cells displayed protection from cell death. Overall these results suggest that LCN2 is involved in prosurvival responses during cell stress and plays an important role in regulating inflammation during retinal degeneration.

Neutrophils Release Metalloproteinases during Adhesion in the Presence of Insulin, but Cathepsin G in the Presence of Glucagon

In patients with reperfusion after ischemia and early development of diabetes, neutrophils can attach to blood vessel walls and release their aggressive bactericide agents, which damage the vascular walls. Insulin and 17β-estradiol (E2) relieve the vascular complications observed in metabolic disorders. In contrast, glucagon plays an essential role in the pathophysiology of diabetes. We studied the effect of hormones on neutrophil secretion during adhesion to fibronectin. Amino acid analysis revealed that proteins secreted by neutrophils are characterized by a stable amino acid profile enriched with glutamate, leucine, lysine, and arginine. The total amount of secreted proteins defined as the sum of detected amino acids was increased in the presence of insulin and reduced in the presence of glucagon. E2 did not affect the amount of protein secretion. Proteome analysis showed that in the presence of insulin and E2, neutrophils secreted metalloproteinases MMP-9 and MMP-8 playing a key role in modulation of the extracellular matrix. In contrast, glucagon induced the secretion of cathepsin G, a key bactericide protease of neutrophils. Cathepsin G can promote the development of vascular complications because of its proinflammatory activity and ability to stimulate neutrophil adhesion via the proteolysis of surface receptors.

Urinary neutrophil gelatinase-associated lipocalin and cystatin C compared to the estimated glomerular filtration rate to predict risk in patients with suspected acute myocardial infarction

INTRODUCTION

Impaired renal function, reflected by estimated glomerular filtration rate (eGFR) or cystatin C, is a strong risk predictor in the presence of acute myocardial infarction (AMI). Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is an early marker of acute kidney injury. uNGAL might also be a good predictor of outcome in patients with cardiovascular disease. Aim of the present study was to evaluate the prognostic value of uNGAL compared to eGFR and cystatin C in patients with suspected AMI.

METHODS

1818 patients were enrolled with suspected AMI. Follow-up information on the combined endpoint of death or non-fatal myocardial infarction was obtained 6months after enrolment and was available in 1804 patients. 63 events (3.5%) were registered.

RESULTS

While cystatin C and eGFR were strong risk predictors for the primary endpoint even adjusted for several variables, uNGAL was not independently associated with outcome: When applied continuously uNGAL was associated with outcome but did not remain a statistically significant predictor after several adjustments (i.e. eGFR). By adding cystatin C or uNGAL to GRACE risk score variables, only cystatin C could improve the predictive value while uNGAL showed no improvement.

CONCLUSION

We could show that cystatin C is an independent risk predictor in patients with suspected AMI and cystatin C can add improvement to the commonly used GRACE risk score. In contrast uNGAL is not independently associated with outcome and seems not to add further prognostic information to GRACE risk score.

Experimental and Human Evidence for Lipocalin-2 (Neutrophil Gelatinase-Associated Lipocalin [NGAL]) in the Development of Cardiac Hypertrophy and heart failure

BACKGROUND

Cardiac hypertrophy increases the risk of developing heart failure and cardiovascular death. The neutrophil inflammatory protein, lipocalin-2 (LCN2/NGAL), is elevated in certain forms of cardiac hypertrophy and acute heart failure. However, a specific role for LCN2 in predisposition and etiology of hypertrophy and the relevant genetic determinants are unclear. Here, we defined the role of LCN2 in concentric cardiac hypertrophy in terms of pathophysiology, inflammatory expression networks, and genomic determinants.

METHODS AND RESULTS

We used 3 experimental models: a polygenic model of cardiac hypertrophy and heart failure, a model of intrauterine growth restriction and Lcn2-knockout mouse; cultured cardiomyocytes; and 2 human cohorts: 114 type 2 diabetes mellitus patients and 2064 healthy subjects of the YFS (Young Finns Study). In hypertrophic heart rats, cardiac and circulating Lcn2 was significantly overexpressed before, during, and after development of cardiac hypertrophy and heart failure. Lcn2 expression was increased in hypertrophic hearts in a model of intrauterine growth restriction, whereas Lcn2-knockout mice had smaller hearts. In cultured cardiomyocytes, Lcn2 activated molecular hypertrophic pathways and increased cell size, but reduced proliferation and cell numbers. Increased LCN2 was associated with cardiac hypertrophy and diastolic dysfunction in diabetes mellitus. In the YFS, LCN2 expression was associated with body mass index and cardiac mass and with levels of inflammatory markers. The single-nucleotide polymorphism, rs13297295, located near LCN2 defined a significant cis-eQTL for LCN2 expression.

CONCLUSIONS

Direct effects of LCN2 on cardiomyocyte size and number and the consistent associations in experimental and human analyses reveal a central role for LCN2 in the ontogeny of cardiac hypertrophy and heart failure.

Antimicrobial Activity of Mesenchymal Stem Cells: Current Status and New Perspectives of Antimicrobial Peptide-Based Therapies

While mesenchymal stem cells (MSCs)-based therapy appears to be promising, there are concerns regarding possible side effects related to the unwanted suppression of antimicrobial immunity leading to an increased risk of infection. Conversely, recent data show that MSCs exert strong antimicrobial effects through indirect and direct mechanisms, partially mediated by the secretion of antimicrobial peptides and proteins (AMPs). In fact, MSCs have been reported to increase bacterial clearance in preclinical models of sepsis, acute respiratory distress syndrome, and cystic fibrosis-related infections. This article reviews the current evidence regarding the direct antimicrobial effector function of MSCs, focusing mainly on the role of MSCs-derived AMPs. The strategies that might modulate the expression and secretion of these AMPs, leading to enhanced antimicrobial effect, are highlighted. Furthermore, studies evaluating the presence of AMPs in the cargo of extracellular vesicles (EVs) are underlined as perspective opportunities to develop new drug delivery tools. The antimicrobial potential of MSCs-derived EVs can also be heightened through cell conditioning and/or drug loading. Finally, improving the pharmacokinetics and delivery, in addition to deciphering the multi-target drug status of AMPs, should synergistically lead to key advances against infections caused by drug-resistant strains.

Neutrophil gelatinase-associated lipocalin levels are U-shaped in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study-Impact for mortality

INTRODUCTION

Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein released by damaged renal tubular cells and mature neutrophils. It is elevated in kidney injury, but also in patients with coronary artery disease (CAD) and myocardial infarction. We investigated the prognostic value of NGAL for total and cardiovascular mortality in patients undergoing coronary angiography without history of renal insufficiency at inclusion into the study.

PARTICIPANTS

The LURIC study is an ongoing prospective cohort study of patients referred for coronary angiography and is designed to evaluate determinants of cardiovascular health.

RESULTS

NGAL was determined in plasma of 2997 persons (mean age: 62.7 years; 69.7% men) with a follow up for 10 years. 2358 patients suffered from CAD and 638 did not-these patients served as controls. Stable CAD was found in 1408 and unstable CAD in 950 patients. Death rate from cardiovascular events and all causes was highest in patients within the 4th quartile of NGAL (≥56 ng/ml, p<0.001 vs third quartile), even after adjustment for age and gender. According to multivariable-adjusted Cox analysis adjusting for well-known cardiovascular risk factors, as well as lipid lowering therapy, angiographic CAD, and C-reactive protein we found patients in the highest NGAL quartile being at increased risk for cardiovascular (hazard ratio (HR) 1.33, 95%CI 1.05-1.67, p = 0.016) and all cause mortality (HR 1.29 95%CI 1.07-1.55, p = 0.007) compared to those in the third quartile. The lowest risk was seen in the third quartile of NGAL (41-56 ng/ml) suggesting a U-shaped relationship between NGAL and mortality. Further adjustment for creatinine abrogated the predictive effect of NGAL. However, the 3rd and 4th quartiles of NGAL were significantly associated with higher neutrophil counts, which were associated with CAD, non-ST elevation and ST-elevation myocardial infarction (p<0.05).

CONCLUSIONS

Plasma NGAL concentrations are mainly derived from neutrophils and do not predict mortality independent of renal function.

Insulin treatment prevents wounding associated changes in tissue and circulating neutrophil MMP-9 and NGAL in diabetic rats

Neutrophils are important for wound repair, but their persistence can impair the healing process. Neutrophils express matrix metalloproteinases including MMP-9 and its regulator neutrophil gelatinase associated lipocalin (NGAL). Whether wounding affects neutrophil MMP-9 and NGAL in diabetic animals is not known. Skin wound tissue MMP-9 and NGAL was examined by qRT-PCR and immunohistochemistry in control, diabetic and insulin treated diabetic rats. The temporal expression of MMP-9 and NGAL mRNA, MMP-9 activity and the NGAL/MMP-9 complex was also investigated in an implant model and their circulating neutrophils. The cellular localisation of MMP-9 and NGAL was confirmed by immunofluorescence and the ability of glucose to regulate these factors was examined in isolated neutrophils. In skin wound tissue compared with control, diabetes increased neutrophil infiltration, NGAL mRNA and MMP-9 protein (P<0.05). Diabetes significantly increased implant neutrophil NGAL and MMP-9 protein as well as NGAL mRNA, wound fluid NGAL/MMP-9 complex and MMP-9 activity (all <0.05). Circulating neutrophil MMP-9 and NGAL was also increased in these diabetic animals (P<0.05). These changes were prevented by insulin treatment. Ex vivo, high glucose (25mM) increased neutrophil NGAL and MMP-9 (both by 2 fold, P<0.05). NGAL and MMP-9 are increased in wound and circulating neutrophils in diabetic rodents. These changes and the association between higher NGAL and increased wound fluid MMP-9 activity suggest that increased neutrophil NGAL may contribute to increased MMP-9 in poorly healing diabetic wounds. Whether targeting neutrophil NGAL or MMP-9 can improve diabetic wound healing remains to be investigated.

Antimicrobial Activity of Mesenchymal Stem Cells: Current Status and New Perspectives of Antimicrobial Peptide-Based Therapies

While mesenchymal stem cells (MSCs)-based therapy appears to be promising, there are concerns regarding possible side effects related to the unwanted suppression of antimicrobial immunity leading to an increased risk of infection. Conversely, recent data show that MSCs exert strong antimicrobial effects through indirect and direct mechanisms, partially mediated by the secretion of antimicrobial peptides and proteins (AMPs). In fact, MSCs have been reported to increase bacterial clearance in preclinical models of sepsis, acute respiratory distress syndrome, and cystic fibrosis-related infections. This article reviews the current evidence regarding the direct antimicrobial effector function of MSCs, focusing mainly on the role of MSCs-derived AMPs. The strategies that might modulate the expression and secretion of these AMPs, leading to enhanced antimicrobial effect, are highlighted. Furthermore, studies evaluating the presence of AMPs in the cargo of extracellular vesicles (EVs) are underlined as perspective opportunities to develop new drug delivery tools. The antimicrobial potential of MSCs-derived EVs can also be heightened through cell conditioning and/or drug loading. Finally, improving the pharmacokinetics and delivery, in addition to deciphering the multi-target drug status of AMPs, should synergistically lead to key advances against infections caused by drug-resistant strains.

Cell autonomous and noncell-autonomous role of NF-κB p50 in astrocyte-mediated fate specification of adult neural progenitor cells

In previous work, we demonstrated that NF-κB p50 acts as crucial regulator of adult hippocampal neural progenitor cells (ahNPC). Indeed, NF-κB p50 knockout (KO) mice are characterized by remarkably reduced hippocampal neurogenesis. As a follow up to that work, herein we show that when cultured in vitro, ahNPC from wild type (WT) and p50KO mice are not significantly different in their neurogenic potential. This observation prompted us to investigate cell-autonomous and noncell-autonomous consequences of p50 absence on neuronal fate specification of ahNPC. In particular, we focused our attention on astrocytes, known to provide soluble proneurogenic signals, and investigated the influence of WT and p50KO astrocyte conditioned media (ACM) on WT and p50KO ahNPC differentiation. Interestingly, while WT ACM promoted both neuronal and astroglial differentiations, p50KO ACM only supported astroglial differentiation of WT ahNPC. By using a LC-MS/MS approach, we identified some proteins, which are significantly upregulated in p50KO compared with WT astrocytes. Among them, lipocalin-2 (LCN-2) was recognized as a novel astroglial-derived signal regulating neuronal fate specification of ahNPC. Interestingly, LCN-2 proneurogenic effect was greatly reduced in p50KO NPC, where LCN-2 receptor gene expression appeared downregulated. In addition to that, we demonstrated p50KO NPC unresponsiveness to both neuronal and astroglial fate specification signals from WT and p50KO ACM, and we identified a reduced expression of α2δ1, a thrombospondin-1 receptor, as another phenotypic change occurring in ahNPC in the absence of p50. Altogether, our data suggest that dysregulated NPC-astrocyte communication may contribute to a reduced hippocampal neurogenesis in p50KO mice in vivo. GLIA 2016 GLIA 2017;65:169-181.

Lipocalin 2 (LCN2) Expression in Hepatic Malfunction and Therapy

Lipocalin 2 (LCN2) is a secreted protein that belongs to the Lipocalins, a group of transporters of small lipophilic molecules such as steroids, lipopolysaccharides, iron, and fatty acids in circulation. Two decades after its discovery and after a high variety of published findings, LCN2's altered expression has been assigned to critical roles in several pathological organ conditions, including liver injury and steatosis, renal damage, brain injury, cardiomyopathies, muscle-skeletal disorders, lung infection, and cancer in several organs. The significance of this 25-kDa lipocalin molecule has been impressively increased during the last years. Data from several studies indicate the role of LCN2 in physiological conditions as well as in response to cellular stress and injury. LCN2 in the liver shows a protective role in acute and chronic injury models where its expression is highly elevated. Moreover, LCN2 expression is being considered as a potential strong biomarker for pathological conditions, including rheumatic diseases, cancer in human organs, hepatic steatosis, hepatic damage, and inflammation. In this review, we summarize experimental and clinical findings linking LCN2 to the pathogenesis of liver disease.

Lipocalin-2 inhibits autophagy and induces insulin resistance in H9c2 cells

Lipocalin-2 (Lcn2; also known as neutrophil gelatinase associated lipocalin, NGAL) levels are increased in obesity and diabetes and associate with insulin resistance. Correlations exist between Lcn2 levels and various forms or stages of heart failure. Insulin resistance and autophagy both play well-established roles in cardiomyopathy. However, little is known about the impact of Lcn2 on insulin signaling in cardiomyocytes. In this study, we treated H9c2 cells with recombinant Lcn2 for 1 h followed by dose- and time-dependent insulin treatment and found that Lcn2 attenuated insulin signaling assessed via phosphorylation of Akt and p70S6K. We used multiple assays to demonstrate that Lcn2 reduced autophagic flux. First, Lcn2 reduced pULK1 S555, increased pULK1 S757 and reduced LC3-II levels determined by Western blotting. We validated the use of DQ-BSA to assess autolysosomal protein degradation and this together with MagicRed cathepsin B assay indicated that Lcn2 reduced lysosomal degradative activity. Furthermore, we generated H9c2 cells stably expressing tandem fluorescent RFP/GFP-LC3 and this approach verified that Lcn2 decreased autophagic flux. We also created an autophagy-deficient H9c2 cell model by overexpressing a dominant-negative Atg5 mutant and found that reduced autophagy levels also induced insulin resistance. Adding rapamycin after Lcn2 could stimulate autophagy and recover insulin sensitivity. In conclusion, our study indicated that acute Lcn2 treatment caused insulin resistance and use of gain and loss of function approaches elucidated a causative link between autophagy inhibition and regulation of insulin sensitivity by Lcn2.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) is Associated with Symptomatic Carotid Atherosclerosis and Drives Pro-inflammatory State In Vitro

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL), a protein found in activated neutrophils, is expressed in kidney tubule cells in response to noxious stimuli, and is thus recognized as a marker of acute kidney injury. Recent studies have suggested that NGAL could also have pathophysiological importance in cardiovascular diseases. The aim of the present study was to examine NGAL expression in human carotid endarterectomy tissues ex vivo as well as the effects of NGAL in the main cell types involved in atherogenesis, namely in human macrophages, endothelial cells, and smooth muscle cells in vitro.

METHODS

NGAL protein was analyzed in human endarterectomy samples from patients with asymptomatic and symptomatic carotid stenosis by immunofluorescence, and NGAL mRNA expression was detected using RealTime-PCR. Human monocyte derived macrophages (MDM), human coronary artery smooth muscle cells (HCASMC), and human umbilical vein endothelial cells (HUVEC) were treated with recombinant human (rh) NGAL at different concentrations. Interleukin (IL)-6, IL-8, and monocyte chemo-attractant protein-1 (MCP-1) were determined by specific enzyme linked immunosorbent assays (ELISAs) in culture supernatants of such treated cells.

RESULTS

Expression of NGAL protein was demonstrated by macrophages, smooth muscle cells, and endothelial cells in human carotid atherosclerotic tissue. NGAL mRNA expression was detected at a higher rate in atherosclerotic tissue of patients with symptomatic carotid stenosis (in 70%; n = 19) compared with asymptomatic patients (in 37%; n = 20, p < .001). Treatment of MDM, HCASMC, and HUVEC with rhNGAL led to a significant (p < 0.05) and concentration dependent increase of pro-inflammatory cytokines IL-6, IL-8, and MCP-1 in all cell types analyzed.

CONCLUSION

By induction of pro-inflammatory mediators in human macrophages, smooth muscle cells and endothelial cells, NGAL, which is predominantly expressed in atherosclerotic plaques of symptomatic patients, could be involved in creating the local and systemic pro-inflammatory environment characteristic for atherosclerosis.

Iron metabolism and regulation by neutrophil gelatinase-associated lipocalin in cardiomyopathy

Neutrophil gelatinase-associated lipocalin (NGAL) has recently become established as an important contributor to the pathophysiology of cardiovascular disease. Accordingly, it is now viewed as an attractive candidate as a biomarker for various disease states, and in particular has recently become regarded as one of the best diagnostic biomarkers available for acute kidney injury. Nevertheless, the precise physiological effects of NGAL on the heart and the significance of their alterations during the development of heart failure are only now beginning to be characterized. Furthermore, the mechanisms via which NGAL mediates its effects are unclear because there is no conventional receptor signalling pathway. Instead, previous work suggests that regulation of iron metabolism could represent an important mechanism of NGAL action, with wide-ranging consequences spanning metabolic and cardiovascular diseases to host defence against bacterial infection. In the present review, we summarize rapidly emerging evidence for the role of NGAL in regulating heart failure. In particular, we focus on iron transport as a mechanism of NGAL action and discuss this in the context of the existing strong associations between iron overload and iron deficiency with cardiomyopathy.

Neutrophil's weapons in atherosclerosis

Neutrophils are important components of immunity associated with inflammatory responses against a broad spectrum of pathogens. These cells could be rapidly activated by proinflammatory stimuli and migrate to the inflamed and infected sites where they release a variety of cytotoxic molecules with antimicrobial activity. Neutrophil antibacterial factors include extracellular proteases, redox enzymes, antimicrobial peptides, and small bioactive molecules. In resting neutrophils, these factors are stored in granules and released upon activation during degranulation. These factors could be also secreted in a neutrophil-derived microparticle-dependent fashion. Neutrophils exhibit a unique property to produce neutrophil extracellular traps (NETs) composed of decondensed chromatin and granular proteins to catch and kill bacteria. Neutrophil-released factors are efficient in inactivation and elimination of pathogens through oxidation-dependent or independent damage of bacterial cells, inactivation and neutralization of virulence factors and other mechanisms. However, in chronic atherosclerosis-associated inflammation, protective function of neutrophils could be impaired and misdirected against own cells. This could lead to deleterious effects and progressive vascular injury. In atherogenesis, a pathogenic role of neutrophils could be especially seen in early stages associated with endothelial dysfunction and induction of vascular inflammation and in late atherosclerosis associated with plaque rupture and atherothrombosis. Assuming a prominent impact of neutrophils in cardiovascular pathology, developing therapeutic strategies targeting neutrophil-specific antigens could have a promising clinical potential.

From the periphery to the brain: Lipocalin-2, a friend or foe?

Lipocalin-2 (LCN2) is an acute-phase protein that, by binding to iron-loaded siderophores, acts as a potent bacteriostatic agent in the iron-depletion strategy of the immune system to control pathogens. The recent identification of a mammalian siderophore also suggests a physiological role for LCN2 in iron homeostasis, specifically in iron delivery to cells via a transferrin-independent mechanism. LCN2 participates, as well, in a variety of cellular processes, including cell proliferation, cell differentiation and apoptosis, and has been mostly found up-regulated in various tissues and under inflammatory states, being its expression regulated by several inducers. In the central nervous system less is known about the processes involving LCN2, namely by which cells it is produced/secreted, and its impact on cell proliferation and death, or in neuronal plasticity and behaviour. Importantly, LCN2 recently emerged as a potential clinical biomarker in multiple sclerosis and in ageing-related cognitive decline. Still, there are conflicting views on the role of LCN2 in pathophysiological processes, with some studies pointing to its neurodeleterious effects, while others indicate neuroprotection. Herein, these various perspectives are reviewed and a comprehensive and cohesive view of the general function of LCN2, particularly in the brain, is provided.

Up-regulation of miR-138 inhibits hypoxia-induced cardiomyocyte apoptosis via down-regulating lipocalin-2 expression

Hypoxia-induced cardiomyocyte apoptosis contributes significantly to the development of numerous cardiac diseases, such as ischemic heart disease, heart failure, etc. Promoting cell survival by inhibiting apoptosis is one of the available strategies to attenuate cardiac dysfunction caused by cardiomyocyte loss. Previous studies have been demonstrated that miR-138 and lipocalin-2 (Lcn2) play important roles in cardiomyocyte apoptosis and survival. We presently determined whether Lcn2 is a target gene of miR-138 involved in hypoxia-induced cardiomyocyte apoptosis. Firstly, mimics of miR-138 were transfected into HL-1 cells to investigate its effect on cell apoptosis. Using 3-(4,5-dimethyl-thiazol-2-y1) 2,5-diphenyl tetrazolium bromide (MTT) and Annexin V-FITC/PI flow cytometer assays, over-expression of miR-138 significantly enhanced the cell growth and significantly attenuated the cell apoptosis in hypoxic conditions. Dual-luciferase reporter gene and western blot results confirmed Lcn2 was a direct target of miR-138. Then, the recombinant plasmid, pcDNA3.1/Lcn2 was transfected into the HL-1 cells that over-expressed miR-138. We further observed that the over-expression of Lcn2 diminished the protection of miR-138 over-expression from hypoxia-induced cell survival and apoptosis. In conclusion, our study demonstrated that up-regulation of miR-138 inhibits the hypoxia-induced cardiomyocyte apoptosis via down-regulating the pro-apoptotic gene expression of Lcn2.

Evidence for preoperative aspirin improving major outcomes in patients with chronic kidney disease undergoing cardiac surgery: a cohort study

BACKGROUND

Effects of aspirin on patients with chronic kidney disease (CKD) remains unclear. This study aimed to examine the effect of preoperative aspirin use on postoperative renal function and 30-day mortality in patients with CKD undergoing cardiac surgery.

METHODS

A retrospective cohort study was performed on consecutive patients (n = 5175) receiving cardiac surgery in 2 tertiary hospitals. Of all patients, 3585 met the inclusion criteria and underwent the analysis to determine the association of preoperative aspirin with incidence of acute kidney injury (AKI) and death based on estimated glomerular filtration rate (eGFR).

RESULTS

Of 3585 patients, 31.5% had CKD (eGFR < 60 mL/min/1.73 m2) at baseline and 27.6% had AKI postoperatively. The baseline eGFR had a nonlinear relationship with the incidence and stages of AKI. As eGFR decreased to 15 to 30 from more than or equal to 90 mL/min/1.73 m2, AKI and 30-day mortality increased to 50.5% from 23.5% and to 11.9% from 2.6%, respectively (P < 0.001). However, preoperative aspirin use was associated with a significant decrease in postoperative AKI and 30-day mortality in patients with CKD undergoing cardiac surgery, in particular, the survival benefit associated with aspirin was greater in patients with CKD (vs normal kidney function): 30-day mortality was reduced by 23.3%, 58.2%, or 70.0% for patients with baseline eGFR more than or equal to 90, 30 to 59, or 15 to 30 mL/min/1.73 m2, respectively (P trend < 0.001).

CONCLUSIONS

For patients with CKD undergoing cardiac surgery, preoperative aspirin therapy was associated with renal protection and mortality decline. The magnitude of the survival benefit was greater in patients with CKD than normal kidney function.

Level of serum neutrophil gelatinase-associated lipocalin in childhood asthma

BACKGROUND

The role of neutrophil gelatinase-associated lipocalin (NGAL) in childhood asthma remains unknown. This study aimed to measure the serum levels of NGAL in children with asthma and to investigate the correlation between NGAL and transforming growth factor beta 1 (TGF-β1), a good indicator of airway remodeling in children with asthma.

METHODS

This prospective, cross-sectional study was conducted on 75 children. Serum NGAL and TGF-β1 concentrations were measured by the ELISA method. Complete blood count, high sensitive C reactive protein (hsCRP), eosinophil cationic protein (ECP), and total serum IgE were investigated in the study population. Atopy in the asthma group was investigated using a skin prick test and specific IgE measurements.

RESULTS

Forty-three asthmatic children and 32 healthy children were enrolled in the study. Total eosinophil numbers, white blood cell count, total serum IgE levels and ECP levels were significantly higher in the asthma group than in the control group (p<0.05). Similarly, serum TGF-β1 levels were significantly higher in children with asthma (p=0.012). The difference in NGAL levels between the groups was insignificant (p=0.268). NGAL levels did not show a significant correlation with total IgE, ECP, eosinophil numbers and TGF-β1 levels (p>0.05).

CONCLUSION

As a conclusion, while elevated TGF-β1 levels in children with asthma might be regarded as an indicator of airway remodeling, we did not find a similar prediction strength for NGAL. Further studies are required to better identify the role of NGAL in childhood asthma and to determine its potential use as a clinical marker.

Biomarkers in post-reperfusion syndrome after acute lower limb ischaemia

Ischaemia reperfusion (I/R) injury refers to tissue damage caused when blood supply returns to the tissue after a period of ischaemia. Matrix metalloproteinases (MMPs), neutrophil gelatinase-associated lipocalin (NGAL) and cytokines are biomarkers involved in several vascular complications. The aim of this study was to evaluate the role of MMPs, NGAL and inflammatory cytokines in I/R syndrome. We conducted an open label, multicentric, parallel group study, between January 2010 and December 2013. Patients with acute limb ischaemia were enrolled in this study and were divided into two groups: (i) those subjected to fasciotomy and (ii) those not subjected to fasciotomy, according to the onset of compartment syndrome. Plasma and tissue values of MMPs and NGAL as well as plasma cytokines were evaluated. MMPs, NGAL and cytokine levels were higher in patients with compartment syndrome. Biomarkers evaluated in this study may be used in the future as predictors of I/R injury severity and its possible evolution towards post-reperfusion syndrome.

A case-control study of pre-operative levels of serum neutrophil gelatinase-associated lipocalin and other potential inflammatory markers in colorectal cancer

Background

Chronic inflammation is a key feature of colorectal cancer (CRC), meaning that inflammatory biomarkers may be useful for its diagnosis. In particular, high neutrophil gelatinase-associated lipocalin (NGAL) expression has been reported in CRC. Thus, we investigated whether serum NGAL and NGAL/MMP-9 could be potential biomarkers for the early detection of CRC. Concurrently, we studied other inflammatory biomarkers such as soluble tumor necrosis factor receptor 1 and 2 (sTNFR-1, sTNFR-2), and C reactive protein (CRP).

Methods

The AGARIC multicenter case–control study was performed in eastern France and included patients admitted for elective surgery either for a priori non-metastatic incident CRC (n = 224) or for benign causes (n = 252). Pre-operative serum levels of NGAL, NGAL/MMP-9, sTNFR-1, sTNFR-2 and CRP were measured.

Results

Median values of serum NGAL, NGAL/MMP-9, sTNFR-1, sTNFR-2 and CRP were significantly higher in CRC patients than in controls. Receiver Operating Characteristic analysis provided relatively poor values of area under the curve, ranging from 0.65 to 0.58. Except for NGAL/MMP-9, all biological parameters were strongly correlated in CRC cases and, less strongly in controls. Multivariate odds ratio (OR) of CRC comparing the extreme tertiles of serum NGAL was 2.76 (95% confidence interval (CI): 1.59-4.78; p < 0.001),. Lower but significant multivariate associations were observed for sTNFR-1, and sTNFR-2: OR = 2.44 (95% CI : 1.34-4.45, p = 0.015) and 1.93 (95% : CI 1.12-3.31), respectively. No independent association was found between case–control status and NGAL/MMP-9. Among CRC cases, maximal tumor size was an independent determinant of serum NGAL (p = 0.028) but this association was reduced after adjustment for CRP (p = 0.11).

Conclusion

Despite a significant increase in serum NGAL and other inflammatory markers among CRC patients, our findings suggest that they may not be suitable biomarkers for the diagnosis and especially early detection of CRC.

Mechanism and clinical evidence of lipocalin-2 and adipocyte fatty acid-binding protein linking obesity and atherosclerosis

Obesity is considered to be a chronic inflammatory state in which the dysfunction of adipose tissue plays a central role. The adipokines, which are cytokines secreted by adipose tissue, are key links between obesity and related diseases such as metabolic syndrome and atherosclerosis. LCN2 and A-FABP, both of which are major adipokines predominantly produced in adipose tissue, have recently been shown to be pivotal modulators of vascular function. However, different adipokines modulate the development of atherosclerosis in distinctive manners, which are partly attributable to their unique regulatory mechanisms and functions. This review highlights recent advances in the understanding of the role of two adipokines in mediating chronic inflammation and the pathogenesis of atherosclerosis.

The relationship between subclinical cardiovascular disease and lipocalin-2 levels in women with PCOS

OBJECTIVE

In this study we aimed to investigate the relationship between lipocalin-2 (LCN2) levels and cardiovascular risk in patients with polycystic ovary syndrome (PCOS).

STUDY DESIGN

Fifty patients with PCOS and 44 healthy women as controls were enrolled in the study. Laboratory and echocardiographic examinations were performed between the second and fifth days of the menstrual cycle. Serum LCN2 levels were measured with an enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

Serum LCN2 levels were significantly lower in PCOS patients (75.8 [51.4-131.2] ng/ml vs. 85.3 [56.7-138.5] ng/ml, p=0.038). Carotid intima-media thickness (CIMT) was increased in patients with PCOS compared to controls (0.61±0.13mm vs. 0.50±0.07mm, p=0.001). Aortic strain was lower in patients with PCOS. Aortic stiffness (β index) was significantly increased and distensibility was decreased in PCOS patients compared to control subjects. Serum LCN2 levels and the presence of PCOS were associated with CIMT in Spearman correlation analysis (p=0.05 and p<0.001) in all participants. There was no statistically significant relationship between LCN2 levels and CIMT in patients with PCOS (p=0.238).

CONCLUSION

In the present study, we found that LCN2 levels were low in women with PCOS. Although our patients with PCOS had elevated cardiac risk, there was no correlation between LCN2 levels and early findings of atherosclerosis.

Association between neutrophil geletinase-associated lipocalin and iron deficiency anemia in children on chronic dialysis

BACKGROUND

Iron deficiency anemia (IDA) in children with chronic kidney disease (CKD) is common and associated with higher risk of death. Neutrophil geletinase-associated lipocalin (NGAL) is a small 25 kDa glycoprotein, a member of lipocalin superfamily that released at the response of cellular stress from different cells. In addition, NGAL was studied as an iron regulatory glycoprotein and regulator of iron related gene. The aim of the current study was to determine any association between serum NGAL and body iron status markers in children on chronic dialysis.

MATERIALS AND METHODS

This correlation study was carried out between May 2012 and May 2013 and evaluated all dialysis patients less than 19 years in pediatric dialysis centers in Isfahan that didn't have exclusion criteria. They were 40 children, including 23 persons on hemodialysis (HD) and 17 persons dialyzed by peritoneal dialysis (PD). Furthermore, we selected 40 children as healthy controls. We examined the relationship between plasma NGAL levels and indices of anemia such as ferritin, transferrin saturation (TSAT) and serum iron (SI) in dialysis children.

RESULTS

Serum NGAL level in children on chronic dialysis (group including both PD and HD patients) was significantly higher than healthy controls (P = 0.008). Furthermore, in this group Serum NGAL level had inverse correlation with TSAT (P = 0.04, r = -0.22), SI (P = 0.04, r = -0.2), white blood cells (P = 0.045, r = -0.26) and serum ferritin (P = 0.006, r = -0.3). In addition, HD patients had higher serum NGAL level than PD patients (P = 0.048).

CONCLUSION

High serum NGAL level in low TSAT group demonstrated that NGAL probably has an important role in IDA in children on chronic dialysis; therefore, it can be a new marker for diagnosis of IDA in CKD.

Plasma neutrophil gelatinase-associated lipocalinin in the general population: association with inflammation and prognosis

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein stored in granules of neutrophil leukocytes participating in inflammatory and atherosclerotic processes and possibly plaque rupture. Despite the putative role of NGAL in atherosclerosis and acute myocardial infarction, human studies of plasma NGAL are still limited.

APPROACH AND RESULTS

We prospectively followed 5599 randomly selected men and women from the community in the fourth Copenhagen Heart Study. Plasma NGAL was measured at study entry. Participants were followed for 10 years. During follow-up, 20% died (n=1120) and 15% (n=884) developed a major adverse cardiovascular event. Plasma NGAL associated strongly with all inflammatory markers (high-sensitivity C-reactive protein, total leukocyte count, neutrophil count) and inversely with estimated glomerular filtration rate (all, P<0.001). Multivariate analysis identified neutrophil leukocyte count as the main determinant of plasma NGAL. During follow-up, participants with increasing NGAL had increased risk of all-cause mortality and major adverse cardiovascular event (both, P<0.001). Even after adjustment for confounding risk factors by Cox regression analysis, NGAL remained an independent predictor of both all-cause mortality and major adverse cardiovascular event. When added to the Framingham risk score, NGAL improved c-statistics and correctly reclassified ≈15% into more appropriate risk groups. In comparison with high-sensitivity C-reactive protein, when both markers were added to the Framingham risk score, NGAL conferred 3× to 4× the risk.

CONCLUSIONS

Plasma NGAL is strongly associated with inflammation in the general population. NGAL independently associated with 10-year outcome, and when added to the Framingham risk score, NGAL both improves c-statistics and correctly reclassifies participants into more accurate risk categories.

Translation Strategy for the Qualification of Drug-induced Vascular Injury Biomarkers

Drug-induced vascular injury (DIVI) is a common preclinical toxicity usually characterized by hemorrhage, vascular endothelial and smooth muscle damage, and inflammation. DIVI findings can cause delays or termination of drug candidates due to low safety margins. The situation is complicated by the absence of sensitive, noninvasive biomarkers for monitoring vascular injury and the uncertain relevance to humans. The Safer And Faster Evidence-based Translation (SAFE-T) consortium is a public–private partnership funded within the European Commission’s Innovative Medicines Initiative (IMI) aiming to accelerate drug development by qualifying biomarkers for drug-induced organ injuries, including DIVI. The group is using patients with vascular diseases that have key histomorphologic features (endothelial damage, smooth muscle damage, and inflammation) in common with those observed in DIVI, and has selected candidate biomarkers associated with these features. Studied populations include healthy volunteers, patients with spontaneous vasculitides and other vascular disorders. Initial results from studies with healthy volunteers and patients with vasculitides show that a panel of biomarkers can successfully discriminate the population groups. The SAFE-T group plans to seek endorsement from health authorities (European Medicines Agency and Food and Drug Administration) to qualify the biomarkers for use in regulatory decision-making processes.