Neutrophil gelatinase-associated lipocalin: a novel inflammatory marker associated with late-life depression

Negative symptoms and neurocognition in drug-naïve schizophrenia: moderating role of plasma neutrophil gelatinase-associated lipocalin (NGAL) and interferon-gamma (INF-γ)

Previous studies reported that peripheral inflammation was associated with cognitive performance and brain structure in schizophrenia. However, the moderating effect of inflammation has not been extensively studied. This study investigated whether inflammation markers moderated the association between negative symptoms and neurocognition in schizophrenia. This cross-sectional study included 137 drug-naïve schizophrenia patients (DNS) and 67 healthy controls (HC). We performed the Measurements and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) for cognitive assessment and the Positive and Negative Syndrome Scale (PANSS) for psychiatric symptoms. Plasma concentrations of interferon-gamma (IFN-γ), neutrophil gelatinase-associated lipocalin (NGAL), and nuclear factor kappa B (NF-κB) were measured. The MCCB neurocognition score, social cognition score, and total score; the plasma concentrations of NGAL, IFN-γ, and NF-κB were significantly decreased in DNS than in HC (all P's < 0.001). PANSS negative subscale (PNS), PANSS reduced expressive subdomain (RES) negatively correlated with neurocognition score (P = 0.007; P = 0.011, respectively). Plasma concentrations of IFN-γ and NGAL positively correlated with neurocognition score (P = 0.043; P = 0.008, relatively). The interactions of PNS × NGAL; PNS × IFN-γ; RES × IFN-γ accounted for significant neurocognition variance (P = 0.025; P = 0.029, P = 0.007, respectively). Simple slope analysis showed that all the above moderating effects only occurred in patients with near normal IFN-γ and NGAL levels. Plasma concentrations of IFN-γ and NGAL moderated the relationship between negative symptoms (especially RES) and neurocognition in schizophrenia. Treatment targeting inflammation may contribute to neurocognition improvement in schizophrenia.

Antidepressant Effect of Heracleum moellendorffii Extract on Behavioral Changes in Astrocyte Ablation Mouse Model of Depression by Modulating Neuroinflammation through the Inhibition of Lipocalin-2

Astrocyte dysfunction and inflammation play a pivotal role in depression. In this study, we evaluated the antidepressant properties of Heracleum moellendorffii root extract (HME), which is traditionally used for inflammation-related diseases, in a mouse model with astrocyte depletion that resembles the prefrontal cortex pathology of depressive patients. Mice were divided into four groups, with 10 mice per group. To induce astrocyte ablation in the mice's prefrontal cortex (PFC), we used astrocytic toxin L-alpha-aminoadipic acid (L-AAA) and administered HME orally at 200 and 500 mg/kg for 22 days. We utilized the tail suspension test (TST) to assess depression-like behaviors and the open field test (OFT) to evaluate anxiety-like activities. Additionally, astrocytic and inflammatory markers in the PFC were evaluated using immunohistochemistry and ELISA. The results showed that infusion of L-AAA significantly decreased the expression of astrocytic glial fibrillary acidic protein (GFAP), which was accompanied by increased depression and anxiety-like behaviors. However, HME significantly reversed these effects by dose-dependently enhancing GFAP expression and modulating inflammatory markers, such as TNF-α, IL-6, and particularly lipocalin-2, a master proinflammatory mediator. These results imply that HME contributes to the alleviation of depression and anxiety-like behaviors by promoting astrocyte recovery and reducing neuroinflammation, especially through lipocalin-2 inhibition.

Sex-specific associations of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in patients with drug-naïve schizophrenia

This present study aimed to investigate the sex-specific association of plasma neutrophil gelatinase-associated lipocalin (NGAL) with cognition in drug-naïve schizophrenia patients for the first time. A total of 204 participants in this study, including 137 drug-naïve schizophrenia (DNS) patients and 67 healthy controls (HCs). All participants completed the Measurements and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB), and were collected fasting venous blood for NGAL measurement. DNS patients also complete the Positive and Negative Syndrome Scale (PANSS). Partial correlation analysis and multiple linear regression were used to explore sex-specific associations between NGAL and cognition. All dimensions of MCCB scores were significantly lower in both male and female DNS patients than HCs. Sex differences were significant in cognitive performance in both DNS patients and HCs. Female DNS patients experienced poorer working memory and reason& problem solving than male patients. Female HCs performed a better attention/vigilance and visual learning, a poorer reason& problem solving than male HCs. In patients with DNS, NGAL levels were negatively associated with positive subscale of PANSS and positively associated with working memory and visual learning only in female. However, there was no significant correlation between NGAL levels and all cognitive tests in both male and female HCs. Regression model showed that higher level of NGAL was an independent protective factor for cognitive performance in female patients with DNS, whereas there was no such role in male patients. Our findings suggest sex specificity between NGAL levels and cognitive performance in DNS patients.

Engeletin alleviates depressive-like behaviours by modulating microglial polarization via the LCN2/CXCL10 signalling pathway

Microglial polarization and associated inflammatory activity are the key mediators of depression pathogenesis. The natural Smilax glabra rhizomilax derivative engeletin has been reported to exhibit robust anti-inflammatory activity, but no studies to date have examined the mechanisms through which it can treat depressive symptoms. We showed that treatment for 21 days with engeletin significantly alleviated depressive-like behaviours in chronic stress social defeat stress (CSDS) model mice. T1-weighted imaging (T1WI), T2-weighted imaging (T2WI) imaging revealed no significant differences between groups, but the bilateral prefrontal cortex of CSDS mice exhibited significant increases in apparent diffusion coefficient and T2 values relative to normal control mice, with a corresponding reduction in fractional anisotropy, while engeletin reversed all of these changes. CSDS resulted in higher levels of IL-1β, IL-6, and TNF-a production, enhanced microglial activation, and greater M1 polarization with a concomitant decrease in M2 polarization in the mPFC, whereas engeletin treatment effectively abrogated these CSDS-related pathological changes. Engeletin was further found to suppress the LCN2/C-X-C motif chemokine ligand 10 (CXCL10) signalling axis such that adeno-associated virus-induced LCN2 overexpression ablated the antidepressant effects of engeletin and reversed its beneficial effects on the M1/M2 polarization of microglia. In conclusion, engeletin can alleviate CSDS-induced depressive-like behaviours by regulating the LCN2/CXCL10 pathway and thereby altering the polarization of microglia. These data suggest that the antidepressant effects of engeletin are correlated with the polarization of microglia, highlighting a potential avenue for future design of antidepressant strategies that specifically target the microglia.

Age-related subtypes of late life depression and mortality: A prospective clinical cohort study

OBJECTIVES

Late Life Depression (LLD) is associated with increased mortality rates, but it remains unclear which depressed patients are at increased risk. This study examined the mortality risk of previously identified subgroups of depressed older patients based on age-related clinical features (the presence of physical and cognitive frailty).

METHODS

A six-year follow-up of a clinical cohort study including 375 depressed older patients and 132 non-depressed persons (NESDO). Depressed patients were diagnosed with the Composite International Diagnostic Interview (CIDI) according to DSM-IV criteria and classified by latent profile analysis on depressive symptom severity, cognitive domains and physical frailty. We estimated the hazard rate of mortality for the four depressed subgroups compared to non-depressed persons by applying Cox-regression analyses. Models were adjusted for age, sex and education as confounders and for explanatory variables per pathway in separate models: somatic burden, lifestyle characteristics, vascular burden or inflammation markers.

RESULTS

A total of 61/375 (16.3%) depressed patients and 8/132 (6.1%) non-depressed persons died during the 6-year follow-up. Two of the four subgroups (n = 186/375 (50%) of the depressed sample) had a higher hazard rate (HR) for mortality compared to non-depressed participants, that is, frail-depressed patients (HR = 5.25, [95%-CI: 2.13-13.0]) and pure mild depressed patients (HR = 3.32 [95%-CI: 1.46-7.58]) adjusted for confounders. Adding possible underlying pathways did not explain these associations.

CONCLUSIONS

Age-related features (the presence of physical and cognitive frailty) contribute to the increased mortality risk in late-life depression. Future studies in depressed older patients should study the additional value of a clinical geriatric assessment and integrated treatment aimed to at reduce frailty and ameliorate their mortality risk.

Increased plasma lipocalin-2 levels are associated with nonmotor symptoms and neuroimaging features in patients with Parkinson's disease

Lipocalin-2 (LCN2) is essential for the regulation of neuroinflammation and cellular uptake of iron. This study aimed to evaluate plasma LCN2 levels and explore their correlation with clinical and neuroimaging features in Parkinson's disease (PD) patients. Enzyme-linked immunosorbent assay (ELISA) was used to measure plasma LCN2 levels in 120 subjects. Evaluation of motor symptoms and nonmotor symptoms in PD patients was assessed by the associated scales. Voxel-based morphometry (VBM) was used to evaluate brain volume alterations, and quantitative susceptibility mapping (QSM) was used to quantitatively analyze brain iron deposition in 46 PD patients. Plasma LCN2 levels were significantly higher in PD patients than those in healthy controls. LCN2 levels were negatively correlated with Montreal Cognitive Assessment (MoCA) scores, total brain gray matter volume (GMV), and GMV/total intracranial volume (TIV) ratio, but positively correlated with Hamilton Anxiety Rating Scale (HAMD) scores and mean QSM values of the bilateral substantial nigra (SN). Receiver operating characteristic (ROC) curves confirmed that plasma LCN2 levels had good predictive accuracy for PD. The results suggest that plasma LCN2 levels have potential as a biomarker for the diagnosis of PD. LCN2 may be a therapeutic target for neuroinflammation and brain iron deposition.

Altered IL-3 and lipocalin-2 levels are associated with the pathophysiology of major depressive disorder: a case-control study

BACKGROUND

Major Depressive Disorder (MDD) is a common mental ailment and is the primary reason for disability. It manifests a severe impact on moods, thoughts, and physical health. At present, this disorder has become a concern in the field of public health. Alteration of neurochemicals is thought to be involved in the pathogenesis of many psychiatric disorders. Therefore, we aimed to evaluate serum IL-3 and lipocalin-2 in MDD patients and healthy controls (HCs).

METHOD

We included a total of 376 participants in this study. Among them, 196 were MDD patients, and 180 were age-sex-matched HCs. MDD patients were recruited from the Psychiatry Department of Bangabandhu Sheikh Mujib Medical University (BSMMU), but the controls were from different parts of Dhaka. All study participants were evaluated by a psychiatrist using the DSM-5 criteria. To assess the severity of the depression, we used the Hamilton depression (Ham-D) rating scale. Serum IL-3 and lipocalin-2 levels were measured using commercially available enzyme-linked immune-sorbent assay kits (ELISA kits).

RESULTS

According to this study, we observed elevated serum levels of IL-3 (1,024.73 ± 29.84 pg/mL) and reduced levels of serum lipocalin-2 (29.019 ± 2.073 ng/mL) in MDD patients compared to HCs (911.11 ± 20.55 pg/mL and 48.065 ± 3.583 ng/mL, respectively). No associations between serum levels of IL-3 and lipocalin-2 and depression severity were observed in patients.

CONCLUSIONS

According to the present findings, alterations of serum IL-3 and lipocalin might be associated with the pathogenesis of MDD. These results support that altered serum neurochemicals can serve as early risk assessment markers for depression. Further interventional studies are recommended for a better understanding of the role of IL-3 and lipocalin-2 in the pathophysiology of depression.

The relationship between inflammatory markers, clinical characteristics, and cognitive performance in drug-naïve patients with schizophrenia

Increasing evidence implicates that inflammatory factors do play a crucial role in the pathophysiology of schizophrenia. However, the association between inflammatory markers and different symptom dimensions and cognitive function of schizophrenia remains unclear. A total of 140 drug-naïve patients with schizophrenia and 69 healthy controls matched for age and gender were enrolled. Peripheral blood plasma concentrations of S-100 calcium-binding protein B (S100B), neutrophil gelatinase-associated lipocalin (NGAL), and interferon-γ (IFN-γ) were detected by enzyme-linked immunosorbent assay (ELISA). Psychotic symptoms were measured using the Positive and Negative Syndrome Scale (PANSS), and cognitive function was assessed by the MATRICS Consensus Cognitive Battery (MCCB). Compared with healthy controls, patients with schizophrenia had significantly worse cognitive function and lower levels of NGAL and IFN-γ (P < 0.001). In schizophrenia, plasma NGAL and IFN-γ levels negatively correlated with positive symptom scores (all P < 0.05). There was a positive correlation between plasma levels of NGAL and IFN-γ with visual learning, neurocognition, and MCCB total score (all P < 0.05). We found that NGAL levels (β = 0.352, t = 5.553, 95% CI 0.228-0.477, P < 0.001) and negative symptoms subscale scores (β = - 0.321, OR = 0.725, 95% CI 648-0.811, P < 0.001) were independently associated with the MCCB total score. Further, binary logistic regression analysis indicated that the concentrations of NGAL (β = - 0.246, OR = 0.782, 95% CI 0.651-0.939, P = 0.008) were independently associated with the diagnosis of schizophrenia. There was a positive correlation between NGAL and IFN-γ levels and MCCB total score in schizophrenia. NGAL level was an independent protective factor for cognitive function and an independent risk factor for the diagnosis of schizophrenia.

Diagnostic value of cerebrospinal fluid Neutrophil Gelatinase-Associated Lipocalin for differentiation of bacterial meningitis from tuberculous meningitis or cryptococcal meningitis: a prospective cohort study

BACKGROUND

The early differential diagnosis between bacterial meningitis (BM) and tuberculous meningitis (TBM) or cryptococcal meningitis (CM) remains a significant clinical challenge. Neutrophil Gelatinase-Associated Lipocalin (NGAL) has been reported as a novel inflammatory biomarker in the early stages of infection. This study aimed to investigate whether cerebrospinal fluid (CSF) NGAL can serve as a potential biomarker for distinguishing between BM and TBM or CM.

METHODS

We prospectively enrolled the patients with suspected CNS infections at admission and divided them into three case groups: BM (n = 67), TBM (n = 55), CM (n = 51), and an age- and sex-matched hospitalized control (HC, n = 58). Detected the CSF NGAL and assessed its diagnostic accuracy in distinguishing between BM and TBM or CM. Additionally, longitudinally measured the CSF NGAL levels in patients with BM to evaluate its potential as a monitoring tool for antibacterial treatment.

RESULTS

The concentration of CSF NGAL in BM was significantly higher than in TBM, CM, and HC (all P < 0.05), while the serum NGAL did not show significant differences among the three case groups. The ROC analysis demonstrated that CSF NGAL presented a good diagnostic performance with an AUC of 0.834 (0.770-0.886) and at the optimal cutoff value of 74.27 ng/mL with 70.15% sensitivity and 77.36% specificity for discriminating BM with TBM and CM. Additionally, the CSF NGAL in the convalescent period of BM was significantly lower than in the acute period (P < 0.05).

CONCLUSIONS

CSF NGAL may serve as a potential biomarker for distinguishing between acute BM and TBM or CM. Additionally, it holds clinical significance in monitoring the effectiveness of antibiotic therapy for BM.

Higher serum lipocalin 2 is associated with post-stroke depression at discharge

BACKGROUND AND AIMS

Post-stroke depression (PSD), as one of the common complications after stroke, seriously affects the physical and mental health and functional prognosis of patients. Previous studies have shown that the increase of inflammatory mediators is associated with the occurrence of PSD. Lipocalin 2 (LCN2), as an acute phase protein, is involved in the development of acute ischemic stroke (AIS), and its expression is up-regulated in patients with depression, suggesting that there is a potential correlation between serum LCN2 and depression. The aim of this study was to explore the relationship between serum LCN2 at admission and PSD at discharge.

METHODS

A total of 358 AIS patients were retrospectively included. All patients had fasting venous blood taken within 24 h of admission to detect serum LCN2. The patients were evaluated by 17-item Hamilton Depression Scale (HAMD) before discharge. Patients with HAMD score > 7 were diagnosed with PSD. The correlation between serum LCN2 and PSD was tested using binary logistic regression analysis.

RESULTS

In our study, 92 (25.7%) patients were diagnosed with PSD at discharge. According to the serum LCN2 value, the patients were divided into three layers (Tertile1 ≤ 105.24ng/ml; Tertile2: 105.24-140.12ng/ml; Tertile3 ≥ 140.12ng/ml), with T1 layer (the lowest levels) as a reference, after adjusting for multiple potential confounding factors, T3 layer (the highest levels) was independently associated with the occurrence of PSD (odds ratio [OR] = 2.639, 95% confidence interval [CI]: 1.317-5.287, P = 0.006). Similar results were found when the serum LCN2 was analyzed as a continuous variable. The optimal cut-off value of serum LCN2 at admission to predict PSD at discharge was 117.60ng/ml, at this threshold, the sensitivity was 77.2%, and the specificity was 53.4%.

CONCLUSIONS

High serum LCN2 levels at admission are an independent risk factor for PSD in patients with AIS at discharge.

Identifying circulating biomarkers for major depressive disorder

Objective

To date, the current diagnosis of major depressive disorder (MDD) still depends on clinical symptomatologic criteria, misdiagnosis and ineffective treatment are common. The study aimed to explore circulating biomarkers for MDD diagnosis.

Methods

A high-throughput antibody array technology was utilized to detect 440 circulating cytokines in eight MDD patients and eight age-and gender-matched healthy controls. LASSO regression was conducted for MDD-related characteristic proteins selection. Enzyme-linked immunosorbent assay (ELISA) was used to validate the characteristic proteins in 40 MDD patients and 40 healthy controls. Receiver operating characteristic (ROC) curve was employed to evaluate the diagnostic values of characteristic proteins for discriminating MDD patients from healthy controls. Correlations between the levels of characteristic proteins and depression severity (HAMD-17 scores) were evaluated using linear regression.

Results

The levels of 59 proteins were found aberrant in MDD patients compared with healthy controls. LASSO regression found six MDD-related characteristic proteins including insulin, CD40L, CD155, Lipocalin-2, HGF and LIGHT. ROC curve analysis showed that the area under curve (AUC) values of six characteristic proteins were more than 0.85 in discriminating patients with MDD from healthy controls. Furthermore, significant relationship was found between the levels of insulin, CD155, Lipocalin-2, HGF, LIGHT and HAMD-17 scores in MDD group.

Conclusion

These results suggested that six characteristic proteins screened from 59 proteins differential in MDD may hold promise as diagnostic biomarkers in discriminating patients with MDD. Among six characteristic proteins, insulin, CD155, Lipocalin-2, HGF and LIGHT might be useful to estimate the severity of depressive symptoms.

Potential Biomarkers of Impulsivity in Mild Traumatic Brain Injury: A Pilot Study

Very few studies have investigated cognition and impulsivity following mild traumatic brain injury (mTBI) in the general population. Furthermore, the neurobiological mechanisms underlying post-TBI neurobehavioral syndromes are complex and remain to be fully clarified. Herein, we took advantage of machine learning based-modeling to investigate potential biomarkers of mTBI-associated impulsivity. Twenty-one mTBI patients were assessed within one-month post-TBI and their data were compared to 19 healthy controls on measures of impulsivity (Barratt Impulsiveness Scale - BIS), executive functioning, episodic memory, self-report cognitive failures and blood biomarkers of inflammation, vascular and neuronal damage. mTBI patients were significantly more impulsive than controls in BIS total and subscales. Serum levels of sCD40L, Cathepsin D, IL-4, Neuropilin-1, IFN-α2, and Copeptin were associated with impulsivity in mTBI patients. Besides showing that mTBI are associated with impulsivity in non-military people, we unveiled different pathophysiological pathways potentially implicated in mTBI-related impulsivity.

Role of lipocalin 2 in stroke

Stroke is the second leading cause of death worldwide; however, the treatment choices available to neurologists are limited in clinical practice. Lipocalin 2 (LCN2) is a secreted protein, belonging to the lipocalin superfamily, with multiple biological functions in mediating innate immune response, inflammatory response, iron-homeostasis, cell migration and differentiation, energy metabolism, and other processes in the body. LCN2 is expressed at low levels in the brain under normal physiological conditions, but its expression is significantly up-regulated in multiple acute stimulations and chronic pathologies. An up-regulation of LCN2 has been found in the blood/cerebrospinal fluid of patients with ischemic/hemorrhagic stroke, and could serve as a potential biomarker for the prediction of the severity of acute stroke. LCN2 activates reactive astrocytes and microglia, promotes neutrophil infiltration, amplifies post-stroke inflammation, promotes blood-brain barrier disruption, white matter injury, and neuronal death. Moreover, LCN2 is involved in brain injury induced by thrombin and erythrocyte lysates, as well as microvascular thrombosis after hemorrhage. In this paper, we review the role of LCN2 in the pathological processes of ischemic stroke; intracerebral hemorrhage; subarachnoid hemorrhage; and stroke-related brain diseases, such as vascular dementia and post-stroke depression, and their underlying mechanisms. We hope that this review will help elucidate the value of LCN2 as a therapeutic target in stroke.

Research Progress on Lipocalin-2 in Diabetic Encephalopathy

Diabetic encephalopathy is a central nervous complication of diabetes mellitus which is characterized by cognitive impairment and structural and neurochemical abnormalities, which is easily neglected. Lipocalin-2 (LCN2) is a 25 kDa transporter in the lipocalin family that can transport small molecules, including fatty acids, iron, steroids, and lipopolysaccharides in the circulation. Recently, LCN2 has been found to be a significant regulator of insulin resistance and glucose homeostasis. Numerous studies have shown that LCN2 is connected to central nervous system abnormalities, including neuroinflammation and neurodegeneration, while the latest researches have found that LCN2 is closely related to the development of diabetic encephalopathy. Nevertheless, its precise role in the pathogenesis of diabetic encephalopathy remains to be determined. In this paper, we review recent evidence on the role of LCN2 in diabetic encephalopathy from multiple perspectives in order to decipher the impact of LCN2 in both the aetiology and treatment of diabetic encephalopathy.

Neutrophil gelatinase-associated lipocalin (NGAL) and tumor necrosis factor-α (TNF-α) levels in patients with schizophrenia

RATIONALE

Although the immune system is thought to contribute to the etiology of schizophrenia, the mechanism has not been elucidated. Clarifying the relationship between them is important in terms of diagnosis, treatment, and prevention approaches.

OBJECTIVE

In this study, it is aimed to determine whether there is any difference in serum levels of neutrophil gelatinase-associated lipocalin (NGAL) and tumor necrosis factor-alpha (TNF-α) in the group of patients with schizophrenia and healthy volunteers, whether these values are changed by medical treatment, whether there is any relation between these values and the severity of the symptoms of patients with schizophrenia, and whether NGAL can be used as a biomarker in the diagnosis and the follow-up of the schizophrenia.

METHODS

A total of 64 patients who were hospitalized in the Psychiatry Clinic of Ankara City Hospital and diagnosed with schizophrenia and 55 healthy volunteers were included in the study. A sociodemographic information form was given to all participants and TNF-α and NGAL values were measured. Positive and Negative Symptoms Rating Scale (PANSS) were applied to the schizophrenia group on admission and follow-up. TNF-α and NGAL levels were re-measured in the 4th week after the start of antipsychotic treatment.

RESULTS

As a result of the present study, it was found that NGAL levels decreased significantly after antipsychotic treatment of schizophrenia patients hospitalized with exacerbation. There was no significant correlation between NGAL and TNF-α levels among schizophrenia and the control group.

CONCLUSION

In psychiatric diseases, especially schizophrenia, there may be differences in immune and inflammatory markers compared to the healthy population. After treatment, the NGAL levels of the patients at follow-up were reduced compared to the levels at admission. It can be thought that NGAL may be related to psychopathology in schizophrenia and antipsychotic treatment. This is the first follow-up study for NGAL levels in schizophrenia.

Plasminogen Activator Inhibitor-1: Potential Inflammatory Marker in Late-life Depression

Objective

Although several previous studies have examined the association between late-life depression and blood adipokine levels, a marker of chronic inflammation, no studies have comprehensively considered the effects of metabolic syndrome, which is known to affect blood adipokine levels. This study examined blood adipokine levels in geriatric depression after adjusting for the effects of metabolic syndrome.

Methods

Participants were selected from the Ansan Geriatric Study (depression group [n = 76] and control group [n = 76]). Blood concentrations of four adipokines (adiponectin, resistin, neutrophil-gelatinase-associated lipocalin [NGAL], and plasminogen activator inhibitor-1 [PAI-1]) were measured using immunoassays. The effects of blood adipokine concentration on the diagnosis of depression were analyzed using multivariate logistic regression to adjust for the effects of metabolic syndrome and potential confounding factors.

Results

When the effects of metabolic syndrome and potential confounding factors were adjusted, only PAI-1 could explain the diagnosis of depression among all the adipokines. The depression group showed a lower blood PAI-1 level than the control group. Adiponectin, resistin, and NGAL could not explain the diagnosis of depression when the effects of metabolic syndrome and potential confounding factors were adjusted.

Conclusion

This study suggests the possibility that the blood PAI-1 levels in clinically pathological late-life depression may show contrasting results to those with subclinical depressive symptoms. Additionally, considering that most previous studies have been conducted with pre-geriatric populations, the study suggests the possibility that geriatric depression may show inflammatory changes with patterns that are different from those of depression in the pre-geriatric population.

Identification of Lipocalin 2 as a Ferroptosis-Related Key Gene Associated with Hypoxic-Ischemic Brain Damage via STAT3/NF-κB Signaling Pathway

Hypoxic-ischemic brain damage (HIBD) is a common cause of death or mental retardation in newborns. Ferroptosis is a novel form of iron-dependent cell death driven by lipid peroxidation, and recent studies have confirmed that ferroptosis plays an important role in the development of HIBD. However, HIBD ferroptosis-related biomarkers remain to be discovered. An artificial neural network (ANN) was established base on differentially expressed genes (DEGs) related to HIBD and ferroptosis and validated by external dataset. The protein-protein interaction (PPI) network, support vector machine-recursive feature elimination (SVM-RFE) algorithms, and random forest (RF) algorithm were utilized to identify core genes of HIBD. An in vitro model of glutamate-stimulated HT22 cell HIBD was constructed, and glutamate-induced ferroptosis and mitochondrial structure and function in HT22 cells were examined by propidium iodide (PI) staining, flow cytometry, Fe²⁺ assay, Western blot, JC-1 kit, and transmission electron microscopy (TEM). In addition, Western blot and immunofluorescence assays were used to detect the NF-κB/STAT3 pathway. An HIBD classification model was constructed and presented excellent performance. The PPI network and two machine learning algorithms indicated two hub genes in HIBD. Lipocalin 2 (LCN2) was the core gene correlated with the risk of HIBD according to the results of differential expression analysis and logistic regression diagnostics. Subsequently, we verified in an in vitro model that LCN2 is highly expressed in glutamate-induced ferroptosis in HT22 cells. More importantly, LCN2 silencing significantly inhibited glutamate-stimulated ferroptosis in HT22 cells. We also found that glutamate-stimulated HT22 cells produced mitochondrial dysfunction. Furthermore, in vitro experiments confirmed that NF-κB and STAT3 were activated and that silencing LCN2 could have the effect of inhibiting their activation. In short, our findings reveal a molecular mechanism by which LCN2 may promote ferroptosis in HIBD through activation of the NF-κB/STAT3 pathway, providing new and unique insights into LCN2 as a biomarker for HIBD and suggesting new preventive and therapeutic strategies for HIBD.

Age-related changes in mice behavior and the contribution of lipocalin-2

Aging causes considerable changes in the nervous system, inducing progressive and long-lasting loss of physiological integrity and synaptic plasticity, leading to impaired brain functioning. These age-related changes quite often culminate in behavioral dysfunctions, such as impaired cognition, which can ultimately result in various forms of neurodegenerative disorders. Still, little is known regarding the effects of aging on behavior. Moreover, the identification of factors involved in regenerative plasticity, in both the young and aged brain, is scarce but crucial from a regenerative point of view and for our understanding on the mechanisms that control the process of normal aging. Recently, we have identified the iron-trafficking protein lipocalin-2 (LCN2) as novel regulator of animal behavior and neuronal plasticity in the young adult brain. On the other hand, others have proposed LCN2 as a biological marker for disease progression in neurodegenerative disorders such as Alzheimer's disease and multiple sclerosis. Still, and even though LCN2 is well accepted as a regulator of neural processes in the healthy and diseased brain, its contribution in the process of normal aging is not known. Here, we performed a broad analysis on the effects of aging in mice behavior, from young adulthood to middle and late ages (2-, 12-, and 18-months of age), and in the absence of LCN2. Significant behavioral differences between aging groups were observed in all the dimensions analyzed and, in mice deficient in LCN2, aging mainly reduced anxiety, while sustained depressive-like behavior observed at younger ages. These behavioral changes imposed by age were further accompanied by a significant decrease in cell survival and neuronal differentiation at the hippocampus. Our results provide insights into the role of LCN2 in the neurobiological processes underlying brain function and behavior attributed to age-related changes.

Antenatal maternal depression, early life inflammation and neurodevelopment in a South African birth cohort

BACKGROUND

Antenatal exposure to maternal psychological adversity, including depression, increases the risk of impaired neurodevelopment in children. The underlying biological mechanisms remain unclear, especially in early life during critical windows of development and maturation. This study investigated the association of antenatal maternal depression, maternal and early life inflammatory markers and neurodevelopmental outcomes in children at 2 years of age.

METHODS

A subgroup of mothers and their children (n = 255) that were enrolled in a South African birth cohort study, the Drakenstein Child Health Study, were followed from the antenatal period through to 2 years of child age. Maternal depressive symptoms were measured by the Beck Depression Inventory (BDI-II) at 26 weeks gestation. Serum inflammatory markers [granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-γ (IFN-γ), interleukin IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, tumour necrosis factor-α (TNF-α), neutrophil gelatinase-associated lipocalin (NGAL) and metalloproteinase-9 (MMP-9)] were measured in mothers at enrolment and in their children at 6-10 weeks and at 2 years. Neurodevelopment was assessed at 2 years using the Bayley Scales of Infant and Toddler Development III.

RESULTS

Antenatal depressive symptoms (present in 25% of the mothers) were significantly associated with higher levels of IL-7 (p = 0.008), IL-8 (p = 0.019) and TNF-α (p = 0.031) in the mothers after correcting for sociodemographic and lifestyle factors. Serum IL-1β and NGAL levels were significantly elevated over time in children born to mothers with depressive symptoms compared to those without depression, after controlling for maternal and child health and sociodemographic factors. Elevated infant IL-1β at 6-10 weeks of age partially mediated the association of maternal depressive symptoms with poorer language scores at 2 years.

CONCLUSION

Alterations in early life immunity, as reflected by elevated IL-1β, is a potential pathway through which antenatal maternal depressive symptoms may impact language development in young children.

The Association between Serum Neutrophil Gelatinase-Associated Lipocalin and Depression in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Patients wtih type 2 diabetes mellitus (DM) have an increased risk of depressive symptoms. Whether serum neutrophil gelatinase-associated lipocalin (NGAL) is associated with depressive symptoms in old patients with type 2 DM is still uncertain.

OBJECTIVE

We aim to investigate whether serum NGAL levels were associated with elevated risk of depressive symptoms in patients with type 2 DM in an old population.

METHODS

Blood samples from 1012 hospitalized patients were measured for serum NGAL within the first 24 hours after admission. The Center for Epidemiological Studies Depression (CES-D) scale was performed to calculate depressive score. Cox analyses were used to examine the prognostic value of serum NGAL on detecting depressive symptoms during a median period of 5 years (range = 0.3-6.2 years).

RESULTS

136 (36.6)% of all subjects have depressive symptoms during the follow-up period. Linear analysis showed that serum NGAL levels at baseline were associated with CES-D score after adjusting for clinically relevant variables in type 2 DM patients (Sβ = 0.118, 95% CI 0.106-0.171, P < .001) but not in non-DM patients (Sβ = 0.025, 95% CI, -0.047-0.083; P = .205). Cox analysis revealed that serum NGAL did have an independent prognostic value on predicting depressive symptoms (HR = 2.247, 95% CI 1.415-3.811, P-trend<0.001, Model 2) in type 2 DM patients but not in non-DM patients (HR = 1.811, 95% CI 1.209-3.292, P-trend = 0.189, Model 2) during follow-up period.

CONCLUSIONS

We found the first evidence that serum NGAL were strongly associated with depressive symptoms in patients with type 2 DM but not in non-DM patients. Further studies are needed to prove the underlying mechanism for the impact of type 2 DM on the association.

The association between the inflammatory response following surgery and post-operative delirium in older oncological patients: a prospective cohort study

INTRODUCTION

Post-operative delirium (POD) is associated with increased morbidity and mortality rates in older patients. Neuroinflammation, the activation of the intrinsic immune system of the brain, seems to be one of the mechanisms behind the development of POD. The aim of this study was to explore the association between the perioperative inflammatory response and the development of POD in a cohort of older oncological patients in need for surgery.

METHODS

In this prospective cohort study, patients 65 years and older in need for oncologic surgery were included. Inflammatory markers C-reactive protein (CRP), interleukin-1 beta (IL-1β), IL-6, IL10 and Neutrophil gelatinase-associated lipocalin (NGAL) were measured in plasma samples pre- and post-operatively. Delirium Observation Screening Scale (DOS) was used as screening instrument for POD in the first week after surgery. In case of positive screening, diagnosis of POD was assessed by a clinician.

RESULTS

Between 2010 and 2016, plasma samples of 311 patients with median age of 72 years (range 65-89) were collected. A total of 38 (12%) patients developed POD in the first week after surgery. The perioperative increase in plasma levels of IL-10 and NGAL were associated with POD in multivariate logistic regression analysis (OR 1.33 [1.09-1.63] P = 0.005 and OR 1.30 [1.03-1.64], P = 0.026, respectively). The biomarkers CRP, IL-1β and IL-6 were not significantly associated with POD.

CONCLUSIONS

Increased surgery-evoked inflammatory responses of IL-10 and NGAL are associated with the development of POD in older oncological patients. The outcomes of this study contribute to understanding the aetiology of neuroinflammation and the development of POD.

Subtyping late-life depression according to inflammatory and metabolic dysregulation: a prospective study

BACKGROUND

Inflammation and metabolic dysregulation are age-related physiological changes and are associated with depressive disorder. We tried to identify subgroups of depressed older patients based on their metabolic-inflammatory profile and examined the course of depression for these subgroups.

METHODS

This clinical cohort study was conducted in a sample of 364 depressed older (⩾60 years) patients according to DSM-IV criteria. Severity of depressive symptoms was monitored every 6 months and a formal diagnostic interview repeated at 2-year follow-up. Latent class analyses based on baseline metabolic and inflammatory biomarkers were performed. Adjusted for confounders, we compared remission of depression at 2-year follow-up between the metabolic-inflammatory subgroups with logistic regression and the course of depression severity over 2-years by linear mixed models.

RESULTS

We identified a 'healthy' subgroup (n = 181, 49.7%) and five subgroups characterized by different profiles of metabolic-inflammatory dysregulation. Compared to the healthy subgroup, patients in the subgroup with mild 'metabolic and inflammatory dysregulation' (n = 137, 37.6%) had higher depressive symptom scores, a lower rate of improvement in the first year, and were less likely to be remitted after 2-years [OR 0.49 (95% CI 0.26-0.91)]. The four smaller subgroups characterized by a more specific immune-inflammatory dysregulation profile did not differ from the two main subgroups regarding the course of depression.

CONCLUSIONS

Nearly half of the patients with late-life depressions suffer from metabolic-inflammatory dysregulation, which is also associated with more severe depression and a worse prognosis. Future studies should examine whether these depressed older patients benefit from a metabolic-inflammatory targeted treatment.

Lipocalin 2 as a link between ageing, risk factor conditions and age-related brain diseases

Chronic (neuro)inflammation plays an important role in many age-related central nervous system (CNS) diseases, including Alzheimer's disease, Parkinson's disease and vascular dementia. Inflammation also characterizes many conditions that form a risk factor for these CNS disorders, such as physical inactivity, obesity and cardiovascular disease. Lipocalin 2 (Lcn2) is an inflammatory protein shown to be involved in different age-related CNS diseases, as well as risk factor conditions thereof. Lcn2 expression is increased in the periphery and the brain in different age-related CNS diseases and also their risk factor conditions. Experimental studies indicate that Lcn2 contributes to various neuropathophysiological processes of age-related CNS diseases, including exacerbated neuroinflammation, cell death and iron dysregulation, which may negatively impact cognitive function. We hypothesize that increased Lcn2 levels as a result of age-related risk factor conditions may sensitize the brain and increase the risk to develop age-related CNS diseases. In this review we first provide a comprehensive overview of the known functions of Lcn2, and its effects in the CNS. Subsequently, this review explores Lcn2 as a potential (neuro)inflammatory link between different risk factor conditions and the development of age-related CNS disorders. Altogether, evidence convincingly indicates Lcn2 as a key constituent in ageing and age-related brain diseases.

Inhibition of Neutrophil Secretion Upon Adhesion as a Basis for the Anti-Inflammatory Effect of the Tricyclic Antidepressant Imipramine

Recent studies demonstrate the involvement of inflammatory processes in the development of depression and the anti-inflammatory effects of antidepressants. Infiltration and adhesion of neutrophils to nerve tissues and their aggressive secretion are considered as possible causes of inflammatory processes in depression. We studied the effect of the antidepressant imipramine on the adhesion and accompanied secretion of neutrophils under control conditions and in the presence of lipopolysaccharides (LPS). As a model of integrin-dependent neutrophil infiltration into tissues, we used integrin-dependent adhesion of neutrophils to the fibronectin-coated substrate. Imipramine inhibited neutrophil adhesion and concomitant secretion of proteins, including matrix metalloproteinase 9 (MMP-9) and neutrophil gelatinase-associated lipocalin (NGAL), which modify the extracellular matrix and basement membranes required for cell migration. Imipramine also significantly and selectively blocked the release of the free amino acid hydroxylysine, a product of lysyl hydroxylase, an enzyme that affects the organization of the extracellular matrix by modifying collagen lysine residues. In contrast, imipramine enhanced the release of ROS by neutrophils during adhesion to fibronectin and stimulated apoptosis. The anti-inflammatory effect of imipramine may be associated with the suppression of neutrophil infiltration and their adhesion to nerve tissues by inhibiting the secretion of neutrophils, which provides these processes.

Elevated levels of neutrophil gelatinase-associated lipocalin among OCD patients: an exploratory study

BACKGROUND

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric disease that is characterized by its clinical heterogeneity and complex pathophysiology. This complexity comes from the diversity of pathophysiological factors that have been proposed to be involved in the natural history of the disorder. Many theories on OCD pathology support inflammation as a pathophysiological factor, although studies are not consistent on the presence of a pro-inflammatory state among OCD patients. However, some pre-clinical animal studies suggest lipocalin-2 (LCN2), an analogous form of the acute-phase pro-inflammatory protein neutrophil gelatinase-associated lipocalin (NGAL), may be involved in in the regulation of the stress response, which is thought to be disrupted in OCD.

METHODS

Twenty-one OCD patients and 19 healthy subjects participated in this exploratory study. Levels of NGAL were assessed in the peripherous blood of all participants. Severity of disease was assessed using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS).

RESULTS

OCD patients exhibited significantly higher levels of NGAL when compared to healthy control subjects. No correlation was found between elevated levels of NGAL and severity of symptoms.

CONCLUSIONS

This is the first study to report elevated levels of NGAL among OCD patients, adding evidence for a possible role of immune dysregulation in the pathophysiology of OCD.

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.

Acute Systemic Inflammatory Response Alters Transcription Profile of Genes Related to Immune Response and Ca2+ Homeostasis in Hippocampus; Relevance to Neurodegenerative Disorders

Acute systemic inflammatory response (SIR) triggers an alteration in the transcription of brain genes related to neuroinflammation, oxidative stress and cells death. These changes are also characteristic for Alzheimer’s disease (AD) neuropathology. Our aim was to evaluate gene expression patterns in the mouse hippocampus (MH) by using microarray technology 12 and 96 h after SIR evoked by lipopolysaccharide (LPS). The results were compared with microarray analysis of human postmortem hippocampal AD tissues. It was found that 12 h after LPS administration the expression of 231 genes in MH was significantly altered (FC > 2.0); however, after 96 h only the S100a8 gene encoding calgranulin A was activated (FC = 2.9). Gene ontology enrichment analysis demonstrated the alteration of gene expression related mostly to the immune-response including the gene Lcn2 for Lipocalin 2 (FC = 237.8), involved in glia neurotoxicity. The expression of genes coding proteins involved in epigenetic regulation, histone deacetylases (Hdac4,5,8,9,11) and bromo- and extraterminal domain protein Brd3 were downregulated; however, Brd2 was found to be upregulated. Remarkably, the significant increase in expression of Lcn2, S100a8, S100a9 and also Saa3 and Ch25h, was found in AD brains suggesting that early changes of immune-response genes evoked by mild SIR could be crucial in AD pathogenesis.

Serum 25-Hydroxyvitamin D Concentrations Are Associated with Mental Health and Psychosocial Stress in Young Adults

We aimed to test the hypothesis that serum 25-hydroxyvitamin D₃ (25(OH)D) concentration is associated with mental health and life stress measures in young adults and investigate gender and racial disparities in these associations. This study comprised 327 black and white participants. Depression, trait anxiety, perceived stress, and hostility were measured by the following validated instruments: Beck Depression Inventory (BDI), State-Trait Anxiety Inventory (STAI), Perceived Stress Scale (PSS), and Cook–Medley Hostility Scale (CMHS). Linear regression was used to estimate correlations between serum 25(OH)D concentration and mental health measurements in the total population and in subgroups stratified by gender and race. In this sample (28.2 ± 3.1 years, 52% female, 53% black), serum 25(OH)D concentration was negatively related to BDI, STAI, PSS, total CMHS score, and the majority of CMHS subscale scores (p-values < 0.05). Stratified by gender, most of these associations remained significant only in women (p-values < 0.05). Stratified by race, higher 25(OH)D concentrations in white participants were significantly related to lower BDI, STAI, PSS, and CMHS-cynicism subscales (p-values < 0.05); 25(OH)D concentrations in the black participants were only inversely associated with CMHS and most CMHS subscales (p-values < 0.05) but not with BDI, STAI, and PSS. We present novel findings of consistent inverse relationships between serum 25(OH)D concentration and various measures of mental health and life stress. Long-term interventional studies are warranted in order to investigate the roles of vitamin D supplementation in the prevention and mitigation of depression, anxiety, and psychological stress in young adults.

Evaluation of serum neutrophil gelatinase-associated lipocalin in older patients with chronic kidney disease

OBJECTIVE

Chronic kidney disease (CKD) is a major health-care burden all over the world, and aging is an important risk factor for end-stage renal disease (ESRD). Neutrophil gelatinase-associated lipocalin (NGAL) has been confirmed as a novel marker for early diagnosis of acute kidney injury. Other studies have found that NGAL takes part in the mechanisms of CKD progression. The aim of this study was to evaluate the expression of serum NGAL in CKD, particularly in elderly patients who rapidly progressed to end-stage renal failure.

METHODS

Serum NGAL, cystatin C, creatinine, urea, and other factors were evaluated in a cohort of 160 CKD patients (mean age 75.29 ± 12.08 years) with various etiologies.

RESULTS

Serum NGAL was closely related to cystatin C, creatinine, urea, and estimated glomerular filtration rate (eGFR). Special correlations between NGAL and, respectively, anemia and hypoalbuminemia were also found. The cutoff value of NGAL was calculated from Stage 2 to Stage 5. Receiver-operator curve analysis showed good area under the curve (>0.8) and high sensitivity (> 70%) on the cutoff value of NGAL. The NGAL levels increased progressively with the increasing of 2- and 5-year risk of ESRD using the Kidney Failure Risk Equations (KFRE).

CONCLUSION

In elderly patients with CKD, serum NGAL reflects renal impairment and presents a strong and independent risk marker for progression of ESRD.

Gender differences in associations of depressive symptoms and anxiety with inflammatory markers in patients with non-obstructive coronary artery disease

OBJECTIVE

The aim of this study was to examine gender differences of the associations between depressive symptoms and anxiety with inflammatory markers in patients with non-obstructive coronary artery disease (NOCAD).

METHODS

Depressive symptoms and anxiety (Beck Depression Inventory BDI and Hospital Anxiety and Depression Scale HADS) were examined in 524 patients with NOCAD (52% women, mean age 64 ± 9 years) as part of the TweeSteden Mild Stenosis (TWIST) observational cohort study. Blood samples were analyzed for neutrophil gelatinase-associated lipocalin (NGAL) levels, high-sensitive C-reactive protein (hsCRP), and leukocyte differentiation. Multivariate analysis for the inflammatory markers with main effects of depressive symptoms or anxiety, gender, and their interactions were observed.

RESULTS

Women had elevated levels of hsCRP, and a lower monocyte and eosinophil count than men, with small to medium effect sizes (range η_(p)² = 0.019-0.047). After Holm-Bonferroni correction depressive symptoms according to the BDI were associated with an overall elevated hsCRP level explaining 2.4% of the hsCRP variance. A significant positive association between BDI cognitive symptoms with elevated hsCRP level was observed in men (R² = 0.045), but not in women (R² < 0.001). Adjustment for age, body mass index, smoking, and physical activity attenuated this finding.

CONCLUSION

Small associations of inflammatory markers with depressive symptoms and anxiety were confounded by lifestyle factors, predominantly smoking. The interacting roles of gender, smoking, and psychological factors on inflammatory markers may point toward different behavioral and inflammatory pathways for women and men with NOCAD, which remains to be further explored.

OBSERVATIONAL COHORT REGISTRATION

ClinicalTrials.gov identifier: NCT01788241.

Adipose Lipocalin 2 overexpression protects against age-related decline in thermogenic function of adipose tissue and metabolic deterioration

OBJECTIVES

Aging increases the risk for development of adipose tissue dysfunction, insulin resistance, dyslipidemia, and liver steatosis. Lipocalin 2 (Lcn2) deficient mice are more prone to diet-induced obesity and metabolic dysfunction, indicating a protective role for Lcn2 in younger mice. In this study, we determined whether overexpressing Lcn2 in adipose tissue can protect against age-related metabolic deterioration.

METHODS

We developed ap2-promoter-driven Lcn2 transgenic (Tg) mice and aged Lcn2 Tg mice for the metabolic assessments.

RESULTS

We found decreased adipocyte size in inguinal white adipose tissue (iWAT) from 10-month-old Lcn2 Tg mice relative to WT. This was accompanied by increased markers of adipogenesis in iWAT and attenuation of the age-related decline in AMP-activated protein kinase (AMPK) phosphorylation in adipose tissue depots. In addition to improvements in adipose tissue function, whole-body metabolic homeostasis was maintained in aged Lcn2 Tg mice. This included improved glucose tolerance and reduced serum triglycerides in older Lcn2 Tg mice relative to WT mice. Further, liver morphology and liver lipid levels were improved in older Lcn2 Tg mice, alongside a decrease in markers of liver inflammation and fibrosis.

CONCLUSIONS

We demonstrate that overexpression of Lcn2 in adipose tissue not only preserves adipose tissue function during aging but also promotes maintenance of glucose tolerance, decreases dyslipidemia, and prevents liver lipid accumulation and steatosis.

Lipocalin-2 is a pathogenic determinant and biomarker of neuropsychiatric lupus

Neuropsychiatric manifestations in lupus (NPSLE) affect ∼20-40% of patients. In the central nervous system, lipocalin-2 (LCN2) can promote injury through mechanisms directly linked to NPSLE, including brain barrier disruption, neurotoxicity, and glial activation. Since LCN2 is elevated in lupus and has been implicated in neuroinflammation, we investigated whether LCN2 is required for the pathogenesis of NPSLE. Here, we investigated the effects of LCN2 deficiency on the development of neurobehavioral deficits in the B6.Sle1.Sle3 (Sle1,3) mouse lupus model. Sle1,3 mice exhibited depression-like behavior and impaired spatial and recognition memory, and these deficits were attenuated in Sle1,3-LCN2KO mice. Whole-brain flow cytometry showed a significant increase in brain infiltrating leukocytes in Sle1,3 mice that was not reduced by LCN2 deficiency. RNA sequencing on sorted microglia revealed that several genes differentially expressed between B6 and Sle1,3 mice were regulated by LCN2, and that these genes are key mediators of the neuroinflammatory cascade. Importantly, LCN2 is upregulated in the cerebrospinal fluid of NPSLE patients across 2 different ethnicities. Our findings establish the Sle1,3 strain as an NPSLE model, demonstrate that LCN2 is a major regulator of the detrimental neuroimmune response in NPSLE, and identify CSF LCN2 as a novel biomarker for NPSLE.

Inflammation in older subjects with early- and late-onset depression in the NESDO study: a cross-sectional and longitudinal case-only design

OBJECTIVE

Different biological mechanisms may underlie depression beginning in early life (early-onset) and depression beginning later in life (late-onset). Although the relation between inflammation and depression has been studied extensively, the distinct role of inflammation in early and late-onset depression in older patients has not been addressed before. In the cross-sectional part of this study, we explored differences in levels of circulating inflammatory markers and cytokine levels in lipopolysaccharide (LPS) stimulated whole blood between older subjects with a late-life onset depression (≥60 years) and older subjects with an early-onset depression (<60 years). Secondly, in a 2-year follow-up study, we examined if circulating and stimulated inflammatory markers influenced the change in Inventory of Depressive Symptomatology (IDS) scores, and if this relation was different for early- and late-onset depression.

METHODS

The study was part of the Netherlands Study of Depression in Older Persons (NESDO). We included 350 patients, all aged 60 and older, with a depressive episode in the previous 6 months: 119 with a late-onset depression and 231 with an early-onset depression. Blood samples were collected and CRP, IL-6, NGAL, GDF15, and, LPS plasma levels were determined and whole blood was LPS stimulated and cytokine levels IL-1β, IL-6, TNFα, IFNγ, IL-10, and IL-1 receptor antagonist (IL-1ra) were determined.

RESULTS

After adjustment for demographics, health indicators, and medication use, increased plasma CRP levels were more strongly associated with late-onset depression than early-onset depression (OR [95% CI]: 1.43 [1.05-1.94]). In the longitudinal analyses, higher circulating IL-6 levels were associated with a significantly slower decline in IDS scores in the crude and the adjusted models (p ≤ 0.027). This relation was not different between late- and early-onset depression. Other circulating and stimulated inflammatory markers were not associated with late- and/or early-onset depression.

CONCLUSIONS

This study provides preliminary evidence that low-grade inflammation is more strongly associated with late-onset than early-onset depression in older adults, suggesting a distinct inflammatory etiology for late-onset depression. Cytokine production capacity did not distinguish between early- and late-onset depression.

Changes in brain white matter structure are associated with urine proteins in urologic chronic pelvic pain syndrome (UCPPS): A MAPP Network study

The Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network has yielded neuroimaging and urinary biomarker findings that highlight unique alterations in brain structure and in urinary proteins related to tissue remodeling and vascular structure in patients with Urological Chronic Pelvic Pain Syndrome (UCPPS). We hypothesized that localized changes in diffusion tensor imaging (DTI) measurements might be associated with corresponding changes in urinary protein levels in UCPPS. To test this hypothesis, we created statistical parameter maps depicting the linear correlation between DTI measurements (fractional anisotropy (FA) and apparent diffusion coefficient (ADC)) and urinary protein quantification (MMP2, MMP9, NGAL, MMP9/NGAL complex, and VEGF) in 30 UCPPS patients from the MAPP Research Network, after accounting for clinical covariates. Results identified a brainstem region that showed a strong correlation between both ADC (R² = 0.49, P<0.0001) and FA (R² = 0.39, P = 0.0002) with urinary MMP9 levels as well as a correlation between both ADC (R² = 0.42, P = 0.0001) and FA (R² = 0.29, P = 0.0020) and urinary MMP9/NGAL complex. Results also identified significant correlations between FA and urinary MMP9 in white matter adjacent to sensorimotor regions (R² = 0.30, P = 0.002; R² = 0.36, P = 0.0005, respectively), as well as a correlation in similar sensorimotor regions when examining ADC and urinary MMP2 levels (R² = 0.42, P<0.0001) as well as FA and urinary MMP9/NGAL complex (R² = 0.33, P = 0.0008). A large, diffuse cluster of white matter was identified as having a strong correlation between both ADC (R² = 0.35, P = 0.0006) and FA (R² = 0.43, P<0.0001) with urinary NGAL levels. In contrast, no significant association between DTI measurements and VEGF was observed. Results suggest that elevated MMP9 or MMP9/NGAL in UCPPS may be related to degenerative neuronal changes in brainstem nuclei through excitotoxicity, while also facilitating synaptic plasticity in sensorimotor regions.

Lipocalin 2 contributes to brain iron dysregulation but does not affect cognition, plaque load, and glial activation in the J20 Alzheimer mouse model

BACKGROUND

Lipocalin 2 (Lcn2) is an acute-phase protein implicated in multiple neurodegenerative conditions. Interestingly, both neuroprotective and neurodegenerative effects have been described for Lcn2. Increased Lcn2 levels were found in human post-mortem Alzheimer (AD) brain tissue, and in vitro studies indicated that Lcn2 aggravates amyloid-β-induced toxicity. However, the role of Lcn2 has not been studied in an in vivo AD model. Therefore, in the current study, the effects of Lcn2 were studied in the J20 mouse model of AD.

METHODS

J20 mice and Lcn2-deficient J20 (J20xLcn2 KO) mice were compared at the behavioral and neuropathological level.

RESULTS

J20xLcn2 KO and J20 mice presented equally strong AD-like behavioral changes, cognitive impairment, plaque load, and glial activation. Interestingly, hippocampal iron accumulation was significantly decreased in J20xLcn2 KO mice as compared to J20 mice.

CONCLUSIONS

Lcn2 contributes to AD-like brain iron dysregulation, and future research should further explore the importance of Lcn2 in AD.

Metabolism and adult neurogenesis: Towards an understanding of the role of lipocalin-2 and iron-related oxidative stress

The process of generating new functional neurons in the adult mammalian brain occurs from the local neural stem and progenitor cells and requires tight control of the progenitor cell's activity. Several signaling pathways and intrinsic/extrinsic factors have been well studied over the last years, but recent attention has been given to the critical role of cellular metabolism in determining the functional properties of progenitor cells. Here, we review recent advances in the current understanding of when and how metabolism affects neural stem cell (NSC) behavior and subsequent neuronal differentiation and highlight the role of lipocalin-2 (LCN2), a protein involved in the control of oxidative stress, as a recently emerged regulator of NSC activity and neuronal differentiation.

Inflammatory markers and cortisol parameters across depressive subtypes in an older cohort

BACKGROUND

There is growing evidence that inflammatory and cortisol dysregulation are underlying pathophysiological mechanisms in the aetiology of major depressive disorder, particularly in younger adults. However, findings of biological disturbances in late-life depression have been divergent, probably due to the even greater heterogeneity of depression in older adults with aging processes influencing biological factors. Using empirically derived subtypes may enable the identification of biological disturbances underlying depression in older adults.

METHODS

Data were used from the Netherlands Study of Depression in Older Persons (NESDO) of 359 persons aged 60 years or older, with a current diagnosis of major depressive disorder (MDD). Depressive subtypes (severe atypical, severe melancholic, and moderate severe subtype) that were previously identified through latent class analysis (LCA), were examined on differences in inflammatory markers including C-reactive protein (CRP), interleukin-6 (IL-6), and neutrophil gelatinase-associated lipocalin (NGAL), as well as cortisol parameters.

RESULTS

No differences in measures for inflammation and cortisol across subtypes were observed in uncorrected or for putative confounders corrected models.

LIMITATIONS

Several subjects had missing cortisol and inflammatory data, decreasing the power. However, results did not change after imputation analysis.

DISCUSSION

In this cohort of depressed older adults, no differences in inflammation and cortisol measures between depression subtypes were observed. This is probably due to the many (patho)physiological processes that are involved in aging, thereby clouding the results.

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.

Neutrophil Gelatinase-Associated Lipocalin and its Receptors in Alzheimer's Disease (AD) Brain Regions: Differential Findings in AD with and without Depression

Co-existing depression worsens Alzheimer’s disease (AD) pathology. Neutrophil gelatinase-associated lipocalin (NGAL) is a newly identified (neuro)inflammatory mediator in the pathophysiologies of both AD and depression. This study aimed to compare NGAL levels in healthy controls, AD without depression (AD–D), and AD with co-existing depression (AD+D) patients. Protein levels of NGAL and its receptors, 24p3R and megalin, were assessed in nine brain regions from healthy controls (n = 19), AD–D (n = 19), and AD+D (n = 21) patients. NGAL levels in AD–D patients were significantly increased in brain regions commonly associated with AD. In the hippocampus, NGAL levels were even further increased in AD+D subjects. Unexpectedly, NGAL levels in the prefrontal cortex of AD+D patients were comparable to those in controls. Megalin levels were increased in BA11 and amygdala of AD+D patients, while no changes in 24p3R were detected. These findings indicate significant differences in neuroimmunological regulation between AD patients with and without co-existing depression. Considering its known effects, elevated NGAL levels might actively promote neuropathological processes in AD with and without depression.

Perspectives in Lipocalin-2: Emerging Biomarker for Medical Diagnosis and Prognosis for Alzheimer's Disease

Lipocalin-2 (LCN2), a secreted glycoprotein belonging to the lipocalin superfamily was reported to participate in various biological processes including cell migration, cell survival, inflammatory responses, and insulin sensitivity. LCN2 is expressed in the multiple tissues such as kidney, liver, uterus, and bone marrow. The receptors for LCN2 were additionally found in microglia, astrocytes, epithelial cells, and neurons, but the role of LCN2 in the central nervous system (CNS) has not been fully understood yet. Recently, in vitro, in vivo, and clinical studies reported the association between LCN2 and the risk of Alzheimer's disease (AD). Here, we reviewed the significant evidences showing that LCN2 contributes to the onset and progression of AD. It may suggest that the manipulation of LCN2 in the CNS would be a crucial target for regulation of the pathogenesis and risk of AD.

Elevation of plasma neutrophil gelatinase-associated lipocalin (NGAL) levels in schizophrenia patients

BACKGROUND

Psychiatric diseases are usually accompanied by immune dysregulation and activation of the inflammatory response system. However, the characteristics of immunoinflammatory markers in psychiatric diseases are not well defined.

METHODS

Seventy-three patients with psychiatric diseases were divided into four groups, including a schizophrenia group, an anxiety disorder group, a unipolar depression group, and a bipolar disorder group, according to the ICD-10 and DSM-IV codes. Neutrophil gelatinase-associated lipocalin (NGAL) and associated classical immunoinflammatory markers including C-reactive protein (CRP), Th1/Th2 cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ), total leukocyte count (TLC), and neutrophilic granulocyte percentage (NEU%) were analysed; patients with physical diseases were excluded to avoid confounders. Fifteen healthy, age- and gender-matched individuals served as controls.

RESULTS

Compared with the corresponding values in the control group, the level of CRP in each psychiatric disease group, the levels of IFN-γ and NGAL in the schizophrenia group, and the NEU% in the depression group were significantly elevated (P < 0.05). Compared with the levels in the schizophrenia group, the levels of CRP in the bipolar disorder and depression groups, the level of IFN-γ in the bipolar disorder group, and the levels of NGAL in the anxiety disorder and depression groups were significantly decreased (P < 0.05). Compared with the depression group, the bipolar disorder group showed significant elevation the NGAL level.

LIMITATION

The sample size was relatively small.

CONCLUSIONS

Immunoinflammatory markers were elevated in patients with psychiatric diseases, especially schizophrenia. We are the first to report that the level of NGAL is significantly increased in schizophrenia patients.

Dynamics of neutrophil gelatinase-associated lipocalin plasma and cerebrospinal fluid concentrations in older males

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is an inflammatory protein with gaining increasing interest for its use as marker in blood and cerebrospinal fluid (CSF) for several chronic diseases. Its biochemical properties make it an attractive marker. However, changes in blood and CSF NGAL concentrations during the diurnal rhythm in the elderly are unknown. This information is important for its optimal use as marker in studies with older people.

METHODS

Serial paired plasma and CSF samples were obtained from 8 healthy elderly males over a 30-hour period. NGAL and cortisol were quantified with ELISA.

RESULTS

No significant changes in plasma and CSF NGAL concentrations over time were found, whereas cortisol (included as internal control) concentrations displayed significant changes over time. Significant circadian patterns were found for plasma NGAL and for cortisol in both plasma and CSF. However, CSF NGAL concentrations did not follow a diurnal pattern in elderly males.

CONCLUSIONS

This study illustrates the temporal regulation of NGAL in plasma and CSF, which potentially is a useful reference for studies measuring NGAL as biomarker in older individuals.

Multimorbidity is associated with increased rates of depression in patients hospitalized with diabetes mellitus in the United States

AIMS

Information on the burden and risk factors for diabetes-depression comorbidity in the US is sparse. We used data from the largest all-payer, nationally-representative inpatient database in the US to estimate the prevalence, temporal trends, and risk factors for comorbid depression among adult diabetic inpatients.

METHODS

We conducted a retrospective analysis using the 2002-2014 Nationwide Inpatient Sample databases. Depression and other comorbidities were identified using ICD-9-CM codes. Logistic regression was used to investigate the association between patient characteristics and depression.

RESULTS

The rate of depression among patients with type 2 diabetes increased from 7.6% in 2002 to 15.4% in 2014, while for type 1 diabetes the rate increased from 8.7% in 2002 to 19.6% in 2014. The highest rates of depression were observed among females, non-Hispanic whites, younger patients, and patients with five or more chronic comorbidities.

CONCLUSIONS

The prevalence of comorbid depression among diabetic inpatients in the US is increasing rapidly. Although some portion of this increase could be explained by the rising prevalence of multimorbidity, increased awareness and likelihood of diagnosis of comorbid depression by physicians and better documentation as a result of the increased adoption of electronic health records likely contributed to this trend.

Neuropsychiatric Disturbances in Alzheimer's Disease: What Have We Learned from Neuropathological Studies?

Neuropsychiatric symptoms (NPS) are an integral part of the dementia syndrome and were therefore recently included in the core diagnostic criteria of dementia. The near universal prevalence of NPS in Alzheimer's disease (AD), combined with their disabling effects on patients and caregivers, is contrasted by the fact that few effective and safe treatments exist, which is in part to be attributed to our incomplete understanding of the neurobiology of NPS. In this review, we describe the pathological alterations typical for AD, including spreading and evolution of burden, effect on the molecular and cellular integrity, functional consequences and atrophy of NPS-relevant brain regions and circuits in correlation with specific NPS assessments. It is thereby clearly established that NPS are fundamental expressions of the underlying neurodegenerative brain disease and not simply reflect the patients' secondary response to their illness. Neuropathological studies, moreover, include a majority of end-stage patient samples, which may not correctly represent the pathophysiological environment responsible for particular NPS that may already be present in an early stage, or even prior to AD diagnosis. The burdensome nature and high prevalence of NPS, in combination with the absence of effective and safe pharmacotherapies, provide a strong incentive to continue neuropathological and neurochemical, as well as imaging and other relevant approaches to further improve our apprehension of the neurobiology of NPS.

Candidate inflammatory biomarkers display unique relationships with alpha-synuclein and correlate with measures of disease severity in subjects with Parkinson's disease

Background

Efforts to identify fluid biomarkers of Parkinson’s disease (PD) have intensified in the last decade. As the role of inflammation in PD pathophysiology becomes increasingly recognized, investigators aim to define inflammatory signatures to help elucidate underlying mechanisms of disease pathogenesis and aid in identification of patients with inflammatory endophenotypes that could benefit from immunomodulatory interventions. However, discordant results in the literature and a lack of information regarding the stability of inflammatory factors over a 24-h period have hampered progress.

Methods

Here, we measured inflammatory proteins in serum and CSF of a small cohort of PD (n = 12) and age-matched healthy control (HC) subjects (n = 6) at 11 time points across 24 h to (1) identify potential diurnal variation, (2) reveal differences in PD vs HC, and (3) to correlate with CSF levels of amyloid β (Aβ) and α-synuclein in an effort to generate data-driven hypotheses regarding candidate biomarkers of PD.

Results

Despite significant variability in other factors, a repeated measures two-way analysis of variance by time and disease state for each analyte revealed that serum IFNγ, TNF, and neutrophil gelatinase-associated lipocalin (NGAL) were stable across 24 h and different between HC and PD. Regression analysis revealed that C-reactive protein (CRP) was the only factor with a strong linear relationship between CSF and serum. PD and HC subjects showed significantly different relationships between CSF Aβ proteins and α-synuclein and specific inflammatory factors, and CSF IFNγ and serum IL-8 positively correlated with clinical measures of PD. Finally, linear discriminant analysis revealed that serum TNF and CSF α-synuclein discriminated between PD and HC with a minimum of 82% sensitivity and 83% specificity.

Conclusions

Our findings identify a panel of inflammatory factors in serum and CSF that can be reliably measured, distinguish between PD and HC, and monitor inflammation as disease progresses or in response to interventional therapies. This panel may aid in generating hypotheses and feasible experimental designs towards identifying biomarkers of neurodegenerative disease by focusing on analytes that remain stable regardless of time of sample collection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-017-0935-1) contains supplementary material, which is available to authorized users.