Cholesterol And Lipids In Depression: Stress, Hypothalamo‐Pituitary‐Adrenocortical Axis, And Inflammation/Immunity

Unveiling the neurolipidome of obsessive-compulsive disorder: A scoping review navigating future diagnostic and therapeutic applications

Obsessive-Compulsive Disorder (OCD) poses a multifaceted challenge in psychiatry, with various subtypes and severities greatly impacting well-being. Recent scientific attention has turned towards lipid metabolism, particularly the neurolipidome, in response to clinical demands for cost-effective diagnostics and therapies. This scoping review integrates recent animal, translational, and clinical studies to explore impaired neurolipid metabolism mechanisms in OCD's pathogenesis, aiming to enhance future diagnostics and therapeutics. Five key neurolipids - endocannabinoids, lipid peroxidation, phospholipids, cholesterol, and fatty acids - were identified as relevant. While the endocannabinoid system shows promise in animal models, its clinical application remains limited. Conversely, lipid peroxidation and disruptions in phospholipid metabolism exhibit significant impacts on OCD's pathophysiology based on robust clinical data. However, the role of cholesterol and fatty acids remains inconclusive. The review emphasises the importance of translational research in linking preclinical findings to real-world applications, highlighting the potential of the neurolipidome as a potential biomarker for OCD detection and monitoring. Further research is essential for advancing OCD understanding and treatment modalities.

The Regulation of Frontal Cortex Cholesterol Metabolism Abnormalities by NR3C1/NRIP1/NR1H2 Is Involved in the Occurrence of Stress-Induced Depression

Stress-induced alterations in central neuron metabolism and function are crucial contributors to depression onset. However, the metabolic dysfunctions of the neurons associated with depression and specific molecular mechanisms remain unclear. This study initially analyzed the relationship between cholesterol and depression using the NHANES database. We then induced depressive-like behaviors in mice via restraint stress. Applying bioinformatics, pathology, and molecular biology, we observed the pathological characteristics of brain cholesterol homeostasis and investigated the regulatory mechanisms of brain cholesterol metabolism disorders. Through the NHANES database, we initially confirmed a significant correlation between cholesterol metabolism abnormalities and depression. Furthermore, based on successful stress mouse model establishment, we discovered the number of cholesterol-related DEGs significantly increased in the brain due to stress, and exhibited regional heterogeneity. Further investigation of the frontal cortex, a brain region closely related to depression, revealed stress caused significant disruption to key genes related to cholesterol metabolism, including HMGCR, CYP46A1, ACAT1, APOE, ABCA1, and LDLR, leading to an increase in total cholesterol content and a significant decrease in synaptic proteins PSD-95 and SYN. This indicates cholesterol metabolism affects neuronal synaptic plasticity and is associated with stress-induced depressive-like behavior in mice. Adeno-associated virus interference with NR3C1 in the prefrontal cortex of mice subjected to short-term stress resulted in reduced protein levels of NRIP1, NR1H2, ABCA1, and total cholesterol content. At the same time, it increased synaptic proteins PSD95 and SYN, effectively alleviating depressive-like behavior. Therefore, these results suggest that short-term stress may induce cholesterol metabolism disorders by activating the NR3C1/NRIP1/NR1H2 signaling pathway. This impairs neuronal synaptic plasticity and consequently participates in depressive-like behavior in mice. These findings suggest that abnormal cholesterol metabolism in the brain induced by stress is a significant contributor to depression onset.

Atherogenic Index of Plasma as a Mediator in the association between Body Roundness Index and Depression: insights from NHANES 2005-2018

BACKGROUND

Previous studies have shown a correlation between depression and obesity, as well as between depression and the Atherogenic Index of Plasma (AIP). However, there is limited research on the association between visceral obesity and depression, as well as the potential mediating role of AIP in this relationship.

METHODS

This study included 13,123 participants from the 2005-2018 National Health and Nutrition Examination Survey. Visceral obesity was measured with the Body Roundness Index (BRI), while depression was evaluated with the Patient Health Questionnaire-9. The AIP served as a marker for lipid disorders. To investigate the association between the BRI and depression, multivariate logistic regressions, restricted cubic spline models, subgroup analyses, and interaction tests were used. Additionally, a mediation analysis was conducted to explore the role of AIP in mediating the effect of BRI on depression.

RESULTS

There was a positive linear correlation between the BRI and depression. After controlling for all covariates, individuals in the highest BRI (Q4) group had an OR of 1.42 for depression (95% CI: 1.12-1.82) in comparison with individuals in the lowest BRI (Q1) group. Moreover, the AIP partially mediated the association between the BRI and depression, accounting for approximately 8.64% (95% CI: 2.04-16.00%) of the total effect.

CONCLUSION

The BRI was positively associated with depression, with the AIP playing a mediating role. This study provides a novel perspective on the mechanism that connects visceral obesity to depression. Managing visceral fat and monitoring AIP levels may contribute to alleviating depression.

Isobaric Tags for Relative and Absolute Quantitation Identification of Blood Proteins Relevant to Paroxetine Response in Patients With Major Depressive Disorder

OBJECTIVES

Isobaric tags for relative and absolute quantitation (iTRAQ) is a proteomic investigation that could be utilized for rapid identification and quantification of proteins, which we would use to identify differentially expressed proteins in treatment responsive patients with major depressive disorder (MDD).

METHODS

Six treatment responsive patients of MDD were recruited, and their peripheral blood mononuclear cell (PBMC) were collected before and after 4 weeks of paroxetine treatment. iTRAQ and Mascot search engine were used to detect differentially expressed proteins, which were then validated by Western blot.

RESULTS

Two thousand one hundred and fifty three proteins were screened, and seven proteins showed differences of more than two-fold and 62 proteins with a differences of less than two-fold. Six proteins with commercially available antibodies were identified, and were validated by Western blot in 10 paroxetine responsive MDD patients. Putative hydroxypyruvate isomerase (HYI), eukaryotic translation initiation factor 4H (eIF4H), and RNA binding motif 8A (RBM8A) had statistically significant differences before and after treatment in the validation. Data are available via ProteomeXchange with identifier PXD028947.

CONCLUSIONS

By using iTRAQ and Western blot, we were able to identify HYI, eIF4H, and RAM8a to be the potential predictors of paroxetine treatment response in patients with MDD. This finding could help establish future individualized medicine.

Lipid Profiles at Birth Predict Teacher-Rated Child Emotional and Social Development 5 Years Later

The fetal environment has been increasingly implicated in later psychological health, but the role of lipids is unknown. Drawing on the ethnically diverse Born in Bradford (BiB) birth cohort, the current study related levels of high-density lipoprotein (HDL), very-low-density lipoprotein (VLDL), and triglycerides in umbilical cord blood to 1,369 children's teacher-rated psychosocial competence approximately 5 years later. Results of ordinal logistic regressions indicated that low levels of HDL, high levels of VLDL, and high levels of triglycerides predicted greater likelihood of being rated as less competent in domains of emotion regulation, self-awareness, and interpersonal functioning. Furthermore, these results generalized across ethnic background and children's sex and were not accounted for by variables reflecting mothers' psychological or physical health, children's physical health, or children's special education status. Together, these results identify fetal exposure to anomalous lipid levels as a possible contributor to subsequent psychological health and social functioning.

Analytical approaches for lipidomics and its potential applications in neuropsychiatric disorders

OBJECTIVES

In this review, the authors discuss an overview of lipidomics followed by in-depth discussion of its application to the study of human diseases, including extraction methods of lipids, analytical techniques and clinical research in neuropsychiatric disorders.

METHODS

Lipidomics is a lipid-targeted metabolomics approach aiming at the comprehensive analysis of lipids in biological systems. Recent technological advancements in mass spectrometry and chromatography have greatly enhanced the development and applications of metabolic profiling of diverse lipids in complex biological samples.

RESULTS

An effective evaluation of the clinical course of diseases requires the application of very precise diagnostic and assessment approaches as early as possible. In order to achieve this, "omics" strategies offer new opportunities for biomarker identification and/or discovery in complex diseases and may provide pathological pathways understanding for diseases beyond traditional methodologies.

CONCLUSIONS

This review highlights the importance of lipidomics for the future perspectives as a tool for biomarker identification and discovery and its clinical application.

Alexithymia, Suicide Ideation, C-Reactive Protein, and Serum Lipid Levels Among Outpatients with Generalized Anxiety Disorder

The aim of the present study was to investigate the relationships between alexithymia, suicide ideation, C-Reactive Protein (CRP), and serum lipid levels in adult outpatients with a DSM-IV diagnosis of Generalized Anxiety Disorder (GAD). Seventy consecutive patients with GAD were recruited and evaluated. Measures were the Hamilton Anxiety Scale, the Toronto Alexithymia Scale (TAS-20), the Scale of Suicide Ideation (SSI), and the Montgomery Åsberg Depression Rating Scale (MADRS). All patients were assessed for: CRP, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglyceridaemia (TG), and very-low-density lipoprotein cholesterol (VLDL-C). TC/HDL-C and LDL-C/HDL-C ratios were also evaluated. Alexithymic patients showed higher scores on almost all rating scales and altered serum CRP and lipid levels vs. non-alexithymics. In the hierarchical regression model, the presence of higher MADRS scores together with higher scores at the Difficulty in Identifying Feelings dimension of TAS-20 were associated with higher rates of suicide ideation. Although alexithymic subjects with GAD may show a CRP and cholesterol dysregulation, this latter seems independent on increased suicide ideation, rather to Difficulty in Identifying Feelings, and subthreshold depressive symptoms. Study limitations and future research implications are discussed.

The influence of inflammatory cytokines in physiopathology of suicidal behavior

BACKGROUND

Based on the urgent need for reliable biomarkers in relation to suicide risk both for more accurate prediction as well as for new therapeutic opportunities, several researchers have been studied evidences of the potential participation of inflammatory processes in the brain, in particular cytokines, in suicide. The purpose of this review was to analyze the associations between inflammation markers and suicide.

METHODS

To achieve this goal, a systematic review of literature was conducted via electronic database Scopus using the Medical Subject Headings (MeSH) terms: "cytokines", "suicide" and "inflammation". Through this search it was found 54 articles. After analyzing them 15 met the eligibility criteria and were included in the final sample.

RESULTS

One of the most mentioned inflammatory markers was Interferon-α (IFN-α), a pro-inflammatory cytokine which has been shown to increase serum concentrations of pro-inflammatory cytokines such as interleukin (IL)-1, IL-6, tumor necrosis factor-a (TNF- α) and IFN-ϒ, which are factors increased suicide victims and attempters. In this line, IL-6 is not only found to be elevated in the cerebrospinal fluid of suicide attempters, even its levels in the peripheral blood have been proposed as a biological suicide marker. Another study stated that increased levels of IL-4 and IL-13 transcription in the orbitofrontal cortex of suicides suggest that these cytokines may affect neurobehavioral processes relevant to suicide.

LIMITATIONS

A lack of studies and great amount of cross-sectional studies.

CONCLUSION

Inflammation may play an important role in the pathophysiology of suicide, especially, levels of some specific inflammatory cytokines.

Advances in biomarkers of major depressive disorder

Major depressive disorder (MDD) is characterized by mood, vegetative, cognitive, and even psychotic symptoms and signs that can cause substantial impairments in quality of life and functioning. Biomarkers are measurable indicators that could help diagnosing MDD or predicting treatment response. In this chapter, lipid profiles, immune/inflammation, and neurotrophic factor pathways that have long been implicated in the pathogenesis of MDD are discussed. Then, pharmacogenetics and epigenetics of serotonin transport and its metabolism pathway, brain-derived neurotrophic factor, and abnormality of hypothalamo-pituitary-adrenocortical axis also revealed new biomarkers. Lastly, new techniques, such as proteomics and metabolomics, which allow researchers to approach the studying of MDD with new directions and make new discoveries are addressed. In the future, more data are needed regarding pathophysiology of MDD, including protein levels, single nucleotide polymorphism, epigenetic regulation, and clinical data in order to better identify reliable and consistent biomarkers for diagnosis, treatment choice, and outcome prediction.

Alexithymia, suicide risk and serum lipid levels among adult outpatients with panic disorder

To elucidate the relationships between alexithymia, suicide ideation and serum lipid levels in drug-naïve adult outpatients with a DSM-IV diagnosis of Panic Disorder (PD), 72 patients were evaluated. Measures were the Panic Attack and Anticipatory Anxiety Scale, the Toronto Alexithymia Scale (TAS-20), the Scale of Suicide Ideation (SSI) and the Montgomery Åsberg Depression Rating Scale (MADRS). Alexithymic patients showed higher scores on all rating scales and altered serum lipid levels than non-alexithymics. In the hierarchical regression model, the presence of lower HDL-C and higher VLDL-C levels and Difficulty in Identifying Feelings dimension of TAS-20 were associated with higher suicide ideation. In conclusion, alexithymic individuals with PD may show a cholesterol dysregulation that may be linked to suicide ideation. The authors discuss study limitations and future research needs.

Principle component analysis combined with matrix-assisted laser desorption ionization mass spectrometry for rapid diagnosing the sera of patients with major depression

BACKGROUND

Previously, we demonstrated that 6M HCl hydrolysis followed by matrix-assisted laser desorption/ionization (MALDI-TOF) mass spectrometry is a useful technique to detect potential protein biomarkers in the sera collected from major depression (MD) patients and from healthy controls.

METHODS

In this study, the effects of various organic acids in hydrolyzing proteins in serum were first examined. The organic matrixes commonly used in MALDI analysis were also examined for characterizing the hydrolyzed peptides. Finally, principle component analysis (PCA) was used to analyze the MALDI mass spectra of acid-hydrolyzed serum samples.

RESULTS

It was found that 20% TFA and sinapinic acid were the optimal reagents for hydrolysis and MALDI matrix. Samples collected from MD patients and healthy controls were readily classified through PCA analysis. A receiver operating characteristic (ROC) curve based on the ratio of the intensities of the two fragment ions (m/z 8606 and 9287) indicated by PCA plot was also constructed. The area under the curve was 0.845; the sensitivity and specificity were both 80%.

CONCLUSIONS

An analytical platform employing trifluoroacetic acid to hydrolyze serum proteins followed by MALDI-TOF/MS and PCA analysis was developed to rapidly differentiate the sera between MD patients and healthy controls.

Alexithymia and its relationships with C-reactive protein and serum lipid levels among drug naïve adult outpatients with major depression

Several studies have investigated the relationship between C-reactive protein (CRP) and serum lipid levels in Major Depression (MD), but no study has, to date, evaluated the impact of alexithymia on these parameters. Therefore, the aim of the present cross-sectional study was to evaluate the relationship between alexithymia, suicide risk, C-reactive protein (CRP) and serum lipid levels in adult outpatients suffering from moderate to severe MD. CRP and serum lipid levels data were analyzed in 145 drug-naïve adult outpatients (69 men, 76 women) with a DSM-IV diagnosis of MD. Alexithymia was measured with the 20-item Toronto Alexithymia Scale (TAS-20), depression severity was evaluated with the 17-item Hamilton Depression Rating Scale (HAM-D) and suicide risk was determined using the Scale of Suicide Ideation (SSI). Alexithymics showed altered serum lipid levels and higher CRP than non-alexithymics. In the linear regression models, lower total cholesterol levels and "Difficulty in Identifying Feelings" dimension of TAS-20 were significantly associated with depression severity, whereas lower high-density lipoprotein levels and "Difficulty in Identifying and Describing Feelings" dimensions of TAS-20 were associated with higher suicide risk. Authors discuss study limitations and future research needs.

Behavioral effects of dietary cholesterol in rats tested in experimental models of mild stress and cognition tasks

Abnormalities in serum cholesterol levels of patients with mood disorders have been identified in epidemiological studies. However, evidence for an influence of dietary cholesterol on behavioral models is poor. Here, we investigated the behavioral changes of Wistar male rats fed a 2% cholesterol-enriched diet for 2 months in experimental models of depression and anxiety, such as the forced swim test (FST) paradigm and the novelty-induced grooming sampling test (NGT). The correlation between behavioral depression and impaired cognitive capacity was also examined testing rats in the Morris water maze (MWM) task one day after the FST. Different groups of rats fed various dietary regimens, were subjected to acute or repeated treatment (14 days) with clomipramine hydrochloride (50 or 25 mg/kg), diazepam (1 mg/kg) or with the peripheral benzodiazepine receptors (PBRs) antagonist, isoquinoline PK11195 (1 mg/kg) injected intraperitoneally (i.p.). Rats fed the cholesterol-enriched diet showed a significant decrease of grooming score in the NGT and of immobility time in the FST in comparison to animals fed a standard diet. Furthermore, the anxiolytic and antidepressant effects of diazepam and clomipramine were not affected by the different diets. Only after repeated treatment, PK11195 impaired the performance of animals fed a standard diet in the FST, and exhibited an anxiolytic-like profile in animals fed either the cholesterol-enriched or the standard diet. The improved performance in the FST was followed by a better learning performance in the acquisition phase of the MWM. These results suggest that effects of cholesterol-enriched diet on the behavioral reaction of rats in experimental models of mild stress may involve PBRs. They deserve attention in order to clarify the clinical correlation between plasma cholesterol levels and mood disorders in humans.

Inflammation: a way to understanding the evolution of portal hypertension

BACKGROUND

Portal hypertension is a clinical syndrome that manifests as ascites, portosystemic encephalopathy and variceal hemorrhage, and these alterations often lead to death.

HYPOTHESIS

Splanchnic and/or systemic responses to portal hypertension could have pathophysiological mechanisms similar to those involved in the post-traumatic inflammatory response.The splanchnic and systemic impairments produced throughout the evolution of experimental prehepatic portal hypertension could be considered to have an inflammatory origin. In portal vein ligated rats, portal hypertensive enteropathy, hepatic steatosis and portal hypertensive encephalopathy show phenotypes during their development that can be considered inflammatory, such as: ischemia-reperfusion (vasodilatory response), infiltration by inflammatory cells (mast cells) and bacteria (intestinal translocation of endotoxins and bacteria) and lastly, angiogenesis. Similar inflammatory phenotypes, worsened by chronic liver disease (with anti-oxidant and anti-enzymatic ability reduction) characterize the evolution of portal hypertension and its complications (hepatorenal syndrome, ascites and esophageal variceal hemorrhage) in humans.

CONCLUSION

Low-grade inflammation, related to prehepatic portal hypertension, switches to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease.

T-helper 1/T-helper 2 cytokine imbalance and clinical phenotypes of acute-phase major depression

Several studies have discussed the relationships between T-helper 1 (Th1) or Th2 cytokines and major depression. The aim of the present study was to investigate the relationships between Th1/Th2 cytokine balance and clinical phenotypes of acute-phase major depression. A total of 82 subjects including 42 patients with major depressive disorder and 40 healthy controls were recruited. Serum cytokine levels of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and IL-10 were examined. Using ancova with age and body mass index (BMI) adjustments, there were no significant differences in serum IL-1beta, TNF-alpha, and IL-10 levels between patients with major depressive disorder and healthy controls. However, using ANCOVA with BMI adjustment only, the results showed that patients with major depressive disorder had significantly higher TNF-alpha levels than control subjects. In addition, using ANCOVA with age and BMI adjustments, significantly higher serum IL-1beta level and IL-1beta/IL-10 ratio were noted in patients with melancholic features than patients with non-melancholic features. However, there were no significant differences in serum IL-1beta, TNF-alpha and IL-10 levels between patients with and without suicide attempt. In conclusion, serum TNF-alpha, IL-1beta level and IL-1beta/IL-10 ratio might play an important role in the psychopathology of acute-phase major depressive disorder.

High-sensitivity C-reactive protein levels in patients with major depressive disorder and bipolar mania

The serum high-sensitivity C-reactive protein (hsCRP) levels in patients with major depressive disorder and bipolar I disorder in acute phases were investigated. During a 1-year period, a total of 67 participants including 23 patients with major depressive disorder, 13 patients with bipolar I disorder (manic episode) and 31 healthy controls were recruited in this study. The diagnoses of mental disorders in participants were made by one psychiatrist according to the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID). Both patient groups with major depression and bipolar disorder had higher mean serum hsCRP levels than the healthy control group. Using analysis of covariance with age adjustment, patients with bipolar I disorders still had significantly higher hsCRP levels than healthy controls (P=0.043). However, patients with major depression did not have significantly higher hsCRP levels than healthy controls (P=0.172). These results suggest that patients with bipolar I disorder might have a more severe inflammation reaction than patients without major depression. However, larger samples and adequate statistical methods are needed to prove these results.