Plasminogen Activator Inhibitor-1 in depression: Results from Animal and Clinical Studies

Stress-Induced Hypercoagulability: Insights from Epidemiological and Mechanistic Studies, and Clinical Integration

By integrating findings from comprehensive reviews, meta-analyses, and cutting-edge genetic studies, this article illuminates the significance of stress-induced hypercoagulability in clinical medicine. In particular, the findings from numerous prospective cohort studies indicate that stress and hemostatic factors of a hypercoagulable state are associated with increased incident risk and poor prognosis for atherosclerotic cardiovascular disease and venous thromboembolism. Mendelian randomization studies suggest that these associations are partially causal. The review synthesizes extensive research on the link between acute and chronic stress and hypercoagulability, outlining a potential pathway from stress to thrombosis risk. Consistent with the allostatic load concept, acute stress-induced hypercoagulability, initially adaptive, can turn maladaptive under chronic stress or excessive acute stress, leading to arterial or venous thrombotic events. Individuals with predisposing factors, including atherosclerosis, thrombophilia, or immobilization, may exhibit an increased risk of thrombotic disease during stress. Contextual sociodemographic characteristics, the stress experience, and coping resources additionally modulate the extent of stress-induced hypercoagulability. Research into the neuroendocrine, cellular, and molecular bases reveals how stress influences platelet activation coagulation and fibrinolysis. The activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, along with vagal withdrawal, and the effects of catecholamines, cortisol, and vasopressin, are the central mechanisms involved. Hemoconcentration, inflammation, endothelial dysfunction, and thrombopoiesis additionally contribute to stress-induced hypercoagulability. Further research is needed to prove a causal link between chronic stress and hypercoagulability. This includes exploring its implications for the prevention and management of thrombotic diseases in stressed individuals, with a focus on developing effective psychosocial and pharmacological interventions.

Increased galanin-galanin receptor 1 signaling, inflammation, and insulin resistance are associated with affective symptoms and chronic fatigue syndrome due to long COVID

BACKGROUND

Patients with Long COVID (LC) often experience neuropsychiatric symptoms such as depression, anxiety, and chronic fatigue syndrome (CFS), collectively referred to as the physio-affective phenome of LC. Activated immune-inflammatory pathways and insulin resistance significantly contribute to the physio-affective phenome associated with LC.

METHODS

In a cohort of 90 individuals, categorized into those with and without LC, we evaluated, 3-6 months following acute SARS-CoV-2 infection, the correlations between the Hamilton Depression (HAMD), Hamilton Anxiety (HAMA), and Fibro-Fatigue (FF) Rating Scale scores, and serum C-reactive protein (CRP), prostaglandin E2 (PGE2), galanin-galanin receptor 1 (GAL-GALR1) signaling, insulin resistance, insulin-like growth factor (IGF-1), plasminogen activator inhibitor-1 (PAI1), S100B and neuron-specific enolase (NSE).

RESULTS

HAMD, HAMA, FF scores, CRP, PGE2, GAL-GALR1 signaling, insulin resistance, PAI1, NSE, and S100B are all higher in people with LC compared to those without LC. The HAMD/HAMA/FF scores were significantly correlated with PGE, CRP, GAL, GALR1, insulin resistance, and PAI1 levels, and a composite score based on peak body temperature (PBT) - oxygen saturation (SpO2) (PBT/SpO2 index) during the acute infectious phase. A combination of biomarkers explained a large part of the variance in CFS and affective scores (33.6%-42.0%), with GAL-GALR1 signaling, PGE2, and CRP being the top 3 most important biomarkers. The inclusion of the PBT/SpO2 index increased the prediction (55.3%-67.1%). The PBT/SpO2 index predicted the increases in GAL-GALR1 signaling.

CONCLUSION

These results indicate that the CFS and affective symptoms that are linked to LC are the consequence of metabolic aberrations, activated immune-inflammatory pathways, and the severity of inflammation during the acute phase of SARS-CoV-2 infection.

From blood to brain: Exploring the role of fibrinogen in the pathophysiology of depression and other neurological disorders

Recent findings indicate that fibrinogen, a protein involved in blood clotting, plays a significant role in neuroinflammation and mood disorders. Elevated fibrinogen levels are consistently observed in individuals with depression, potentially contributing to microglial activation. This could impair fibrinolysis and contribute to a pro-inflammatory environment in the brain. This neuroinflammatory response can impair neuroplasticity, a key process for learning, memory, and mood regulation. Fibrinogen may also indirectly influence neurotransmitters like serotonin, which play a vital role in mood regulation. Furthermore, fibrinogen's interaction with astrocytes may trigger a cascade of events leading to demyelination, a process where the protective sheath around nerve fibers deteriorates. This can disrupt communication within the nervous system and contribute to depression symptoms. Intriguingly, targeting fibrinogen or related pathways holds promise for therapeutic interventions. For instance, modulating PAI-1 (Plasminogen activator inhibitor-1) activity or inhibiting fibrinogen's interaction with brain cells could be potential strategies. This review explores the multifaceted relationship between fibrinogen and neurological disorders with a focus on depression highlighting its potential as a therapeutic target. Further research is necessary to fully elucidate the mechanisms underlying this association and develop effective therapeutic strategies targeting the fibrinolytic system for mood disorders.

Disruption of Lipid Profile, Glucose Metabolism, and Leptin Levels following Citalopram Administration and High-Carbohydrate and High-Cholesterol Diet in Mice

INTRODUCTION

Depression therapy has been linked to negative effects on energy metabolism, which can be attributed to various factors, including an ongoing inflammatory process commonly seen in metabolic disorders. Unhealthy lifestyle choices of patients and the impact of antidepressants on body weight and lipid and glucose metabolism also contribute to these metabolic side effects. Although not as pronounced as other psychopharmaceuticals, the increasing use of antidepressants raises concerns about their potential impact on public health. The study aimed to evaluate the short- and long-term effects of the antidepressant citalopram and its long-term combination with a special diet on metabolic parameters in mice.

METHODS

Animals were randomly divided into 5 groups - control, control + special diet, citalopram (10 mg/kg for 35 days), citalopram + special diet (10 mg/kg for 35 days), and citalopram (10 mg/kg for 7 days). After a described time of administration, animals were anesthetized, blood and fat and liver tissues were collected. Biochemical parameters of lipid metabolism (total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides) and glucose were analyzed using spectrophotometry and relevant adipokines and cytokines were evaluated by ELISA.

RESULTS

After a week of application of citalopram, we observed dyslipidemia that persisted even at the end of the 5-week experiment. Furthermore, after 5 weeks of citalopram administration, we observed a significant decrease in body weight gain and decreased leptin levels. Changes in lipid metabolism, higher levels of adipokines leptin and PAI-1 were observed due to the special diet after 5 weeks.

CONCLUSIONS

Our research suggests that the effects of citalopram and a diet on the metabolism of mice can be significant, both in the short term (1 week) and in the long term (5 weeks).

A Potential Link between Myeloperoxidase Modified LDL, Atherosclerosis and Depression

Atherosclerosis is a chronic inflammatory disease that involves modified low-density lipoproteins (LDL) which play a pivotal role in the initiation and progression of the disease. Myeloperoxidase oxidized LDL (Mox-LDL) is considered to be the most patho-physiologically relevant type of modified LDL and has been reported to be ubiquitously present in atheroma plaques of patients with atherosclerosis. Besides its involvement in the latter disease state, Mox-LDL has also been shown to be implicated in the pathogenesis of various illnesses including sleep disorders, which are in turn associated with heart disease and depression in many intricate ways. Meanwhile, we have recently shown that lox-1-mediated Mox-LDL signaling modulates neuroserpin activity in endothelial cells, which could have major implications that go beyond the pathophysiology of stroke and cerebrovascular disease (CD). Of note is that tissue plasminogen activator (tPA), which is the main target of neuroserpin in the brain, has a crucial function in the processing of brain-derived neurotrophic factor (BDNF) into its mature form. This factor is known to be involved in major depressive disorder (MDD) development and pathogenesis. Since tPA is more conventionally recognized as being involved in fibrinolytic mechanisms, and its effect on the BDNF system in the context of MDD is still not extensively studied, we speculate that any Mox-LDL-driven change in the activity of tPA in patients with atherosclerosis may lead to a decrease in the production of mature BDNF, resulting in impaired neural plasticity and depression. Deciphering the mechanisms of interaction between those factors could help in better understanding the potentially overlapping pathological mechanisms that regulate disease processes in CD and MDD, supporting the possibility of novel and common therapeutic opportunities for millions of patients worldwide.

Serum PAI-1/BDNF Ratio Is Increased in Alzheimer's Disease and Correlates with Disease Severity

We previously demonstrated that serum levels of plasminogen activator inhibitor-1 (PAI-1), which inhibits both the tissue plasminogen activator (tPA) and plasmin activity, are increased in patients with Alzheimer's disease. tPA/plasmin not only prevents the accumulation of β-amyloid in the brain but also is involved in the synthesis of the brain-derived neurotrophic factor (BDNF), a neurotrophin whose levels are reduced in Alzheimer. In the present study, we compared BDNF serum levels in Alzheimer patients with dementia to those in Alzheimer patients with amnestic mild cognitive impairment and to cognitively healthy controls. Moreover, we examined whether the PAI-1/BDNF ratio correlates with disease severity, as measured by Mini-Mental State Examination. Our results showed that BDNF serum levels are lower (13.7% less) and PAI-1 levels are higher in Alzheimer patients with dementia than in Alzheimer patients with amnestic mild cognitive impairment patients (23% more) or controls (36% more). Furthermore, the PAI-1/BDNF ratio was significantly increased in Alzheimer patients as compared to amnestic mild cognitive impairment (36.4% more) and controls (40% more). Lastly, the PAI-1/BDNF ratio negatively correlated with the Mini-Mental score. Our results suggest that increased PAI-1 levels in Alzheimer, by impairing the production of the BDNF, are implicated in disease progression. They also indicate that the PAI-1/BDNF ratio could be used as a marker of Alzheimer. In support of this hypothesis, a strong negative correlation between the PAI-1/BDNF ratio and the Mini-Mental score was observed.

Nrf2 regulates iron-dependent hippocampal synapses and functional connectivity damage in depression

Neuronal iron overload contributes to synaptic damage and neuropsychiatric disorders. However, the molecular mechanisms underlying iron deposition in depression remain largely unexplored. Our study aims to investigate how nuclear factor-erythroid 2 (NF-E2)-related factor 2 (Nrf2) ameliorates hippocampal synaptic dysfunction and reduces brain functional connectivity (FC) associated with excessive iron in depression. We treated mice with chronic unpredictable mild stress (CUMS) with the iron chelator deferoxamine mesylate (DFOM) and a high-iron diet (2.5% carbonyl iron) to examine the role of iron overload in synaptic plasticity. The involvement of Nrf2 in iron metabolism and brain function was assessed using molecular biological techniques and in vivo resting-state functional magnetic resonance imaging (rs-fMRI) through genetic deletion or pharmacologic activation of Nrf2. The results demonstrated a significant correlation between elevated serum iron levels and impaired hippocampal functional connectivity (FC), which contributed to the development of depression-induced CUMS. Iron overload plays a crucial role in CUMS-induced depression and synaptic dysfunction, as evidenced by the therapeutic effects of a high-iron diet and DFOM. The observed iron overload in this study was associated with decreased Nrf2 levels and increased expression of transferrin receptors (TfR). Notably, inhibition of iron accumulation effectively attenuated CUMS-induced synaptic damage mediated by downregulation of brain-derived neurotrophic factor (BDNF). Nrf2-/- mice exhibited compromised FC within the limbic system and the basal ganglia, particularly in the hippocampus, and inhibition of iron accumulation effectively attenuated CUMS-induced synaptic damage mediated by downregulation of brain-derived neurotrophic factor (BDNF). Activation of Nrf2 restored iron homeostasis and reversed vulnerability to depression. Mechanistically, we further identified that Nrf2 deletion promoted iron overload via upregulation of TfR and downregulation of ferritin light chain (FtL), leading to BDNF-mediated synapse damage in the hippocampus. Therefore, our findings unveil a novel role for Nrf2 in regulating iron homeostasis while providing mechanistic insights into poststress susceptibility to depression. Targeting Nrf2-mediated iron metabolism may offer promising strategies for developing more effective antidepressant therapies.

Accelerated epigenetic aging and decreased natural killer cells based on DNA methylation in patients with untreated major depressive disorder

Major depressive disorder (MDD) is known to cause significant disability. Genome-wide DNA methylation (DNAm) profiles can be used to estimate biological aging and as epigenetic clocks. However, information on epigenetic clocks reported in MDD patients is inconsistent. Since antidepressants are likely confounders, we evaluated biological aging using various DNAm-based predictors in patients with MDD who had never received depression medication. A publicly available dataset consisting of whole blood samples from untreated MDD patients (n = 40) and controls (n = 40) was used. We analyzed five epigenetic clocks (HorvathAge, HannumAge, SkinBloodAge, PhenoAge, and GrimAge), DNAm-based telomere length (DNAmTL), and DNAm-based age-related plasma proteins (GrimAge components), as well as DNAm-based white blood cell composition. The results indicate that patients with untreated MDD were significantly associated with epigenetic aging acceleration in HannumAge and GrimAge. Furthermore, a decrease in natural killer cells, based on DNAm, was observed in patients with untreated MDD.

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.

Shared Genetic Regulatory Networks Contribute to Neuropathic and Inflammatory Pain: Multi-Omics Systems Analysis

The mechanisms of chronic pain are complex, and genetic factors play an essential role in the development of chronic pain. Neuropathic pain (NP) and inflammatory pain (IP) are two primary components of chronic pain. Previous studies have uncovered some common biological processes in NP and IP. However, the shared genetic mechanisms remained poorly studied. We utilized multi-omics systematic analyses to investigate the shared genetic mechanisms of NP and IP. First, by integrating several genome-wide association studies (GWASs) with multi-omics data, we revealed the significant overlap of the gene co-expression modules in NP and IP. Further, we uncovered the shared biological pathways, including the previously reported mitochondrial electron transport and ATP metabolism, and stressed the role of genetic factors in chronic pain with neurodegenerative diseases. Second, we identified 24 conservative key drivers (KDs) contributing to NP and IP, containing two well-established pain genes, IL1B and OPRM1, and some novel potential pain genes, such as C5AR1 and SERPINE1. The subnetwork of those KDs highlighted the processes involving the immune system. Finally, gene expression analysis of the KDs in mouse models underlined two of the KDs, SLC6A15 and KCNQ5, with unidirectional regulatory functions in NP and IP. Our study provides strong evidence to support the current understanding of the shared genetic regulatory networks underlying NP and IP and potentially benefit the future common therapeutic avenues for chronic pain.

Electroconvulsive Therapy in Psychiatric Disorders: A Narrative Review Exploring Neuroendocrine-Immune Therapeutic Mechanisms and Clinical Implications

Electroconvulsive therapy (ECT) is based on conducting an electrical current through the brain to stimulate it and trigger generalized convulsion activity with therapeutic ends. Due to the efficient use of ECT during the last years, interest in the molecular bases involved in its mechanism of action has increased. Therefore, different hypotheses have emerged. In this context, the goal of this review is to describe the neurobiological, endocrine, and immune mechanisms involved in ECT and to detail its clinical efficacy in different psychiatric pathologies. This is a narrative review in which an extensive literature search was performed on the Scopus, Embase, PubMed, ISI Web of Science, and Google Scholar databases from inception to February 2022. The terms "electroconvulsive therapy", "neurobiological effects of electroconvulsive therapy", "molecular mechanisms in electroconvulsive therapy", and "psychiatric disorders" were among the keywords used in the search. The mechanisms of action of ECT include neurobiological function modifications and endocrine and immune changes that take place after ECT. Among these, the decrease in neural network hyperconnectivity, neuroinflammation reduction, neurogenesis promotion, modulation of different monoaminergic systems, and hypothalamus-hypophysis-adrenal and hypothalamus-hypophysis-thyroid axes normalization have been described. The majority of these elements are physiopathological components and therapeutic targets in different mental illnesses. Likewise, the use of ECT has recently expanded, with evidence of its use for other pathologies, such as Parkinson's disease psychosis, malignant neuroleptic syndrome, post-traumatic stress disorder, and obsessive-compulsive disorder. In conclusion, there is sufficient evidence to support the efficacy of ECT in the treatment of different psychiatric disorders, potentially through immune, endocrine, and neurobiological systems.

PAI-1: A Major Player in the Vascular Dysfunction in Obstructive Sleep Apnea?

Obstructive sleep apnea is a chronic and prevalent condition that is associated with endothelial dysfunction, atherosclerosis, and imposes excess overall cardiovascular risk and mortality. Despite its high prevalence and the susceptibility of CVD patients to OSA-mediated stressors, OSA is still under-recognized and untreated in cardiovascular practice. Moreover, conventional OSA treatments have yielded either controversial or disappointing results in terms of protection against CVD, prompting the need for the identification of additional mechanisms and associated adjuvant therapies. Plasminogen activator inhibitor-1 (PAI-1), the primary inhibitor of tissue-type plasminogen activator (tPA) and urinary-type plasminogen activator (uPA), is a key regulator of fibrinolysis and cell migration. Indeed, elevated PAI-1 expression is associated with major cardiovascular adverse events that have been attributed to its antifibrinolytic activity. However, extensive evidence indicates that PAI-1 can induce endothelial dysfunction and atherosclerosis through complex interactions within the vasculature in an antifibrinolytic-independent matter. Elevated PAI-1 levels have been reported in OSA patients. However, the impact of PAI-1 on OSA-induced CVD has not been addressed to date. Here, we provide a comprehensive review on the mechanisms by which OSA and its most detrimental perturbation, intermittent hypoxia (IH), can enhance the transcription of PAI-1. We also propose causal pathways by which PAI-1 can promote atherosclerosis in OSA, thereby identifying PAI-1 as a potential therapeutic target in OSA-induced CVD.

Clostridium butyricum RH2 Alleviates Chronic Foot Shock Stress-Induced Behavioral Deficits in Rats via PAI-1

Recent investigations have demonstrated that the chronic stress-induced behavioral disorders can be ameliorated by probiotics including Clostridium butyricum (C. butyricum) via the gut-brain-axis. However, the molecular mechanisms underlying the beneficial effects of C. butyricum on brain remain largely unknown. Here, we investigated whether chronic foot shock stress (CFSS) paradigm used for a hypertensive animal model could induce mood disorders such as anxiety, depression and cognitive impairments. Then, we assessed the impact of C. butyricum RH2 on the behavior disorders and neurobiological alterations in the hippocampus. Male Sprague-Dawley (SD) rats received intermittent electric shocks for consecutive 14 days and were treated with C. butyricum RH2 for 17 days. Anxiety- or depression-like behaviors were evaluated by open field test (OFT), and elevated plus maze (EPM). The Morris water maze test (MWM) was used to evaluate the cognitive functions. CFSS intervention led to mild anxiety- or depression-like behavior or cognitive impairment and C. butyricum RH2 treatment reversed the CFSS-induced symptoms. The serum ACTH or CORT was increased following CFSS but was completely reversed by C. butyricum RH2 treatment. In the hippocampus of CFSS rats, the expressions of BDNF and TrkB were downregulated but proBDNF and P75^NTR were upregulated. These expression changes were partially reversed by C. butyricum RH2, suggesting a mode of action on BDNF and proBDNF balance. CFSS exposure resulted in downregulation of tissue-type plasminogen activator (tPA) but upregulation of plasminogen activator inhibitor 1(PAI-1), which could contribute to the decrease in BDNF by reduced conversion from proBDNF to BDNF in the hippocampus. C. butyricum RH2 treatment reversed the upregulated PAI-1 but not the downregulated tPA, which was in parallel with the amelioration of behavioral abnormalities, suggesting a novel tPA independent mechanism for PAI-1 action. Our results demonstrate for the first time that C. butyricum RH2 attenuates stress-induced behavior disorders via inhibiting the expression of brain PAI-1.

Astrocytes in Post-traumatic Stress Disorder

Although posttraumatic stress disorder (PTSD) is on the rise, traumatic events and their consequences are often hidden or minimized by patients for reasons linked to PTSD itself. Traumatic experiences can be broadly classified into mental stress (MS) and traumatic brain injury (TBI), but the cellular mechanisms of MS- or TBI-induced PTSD remain unknown. Recent evidence has shown that the morphological remodeling of astrocytes accompanies and arguably contributes to fearful memories and stress-related disorders. In this review, we summarize the roles of astrocytes in the pathogenesis of MS-PTSD and TBI-PTSD. Astrocytes synthesize and secrete neurotrophic, pro- and anti-inflammatory factors and regulate the microenvironment of the nervous tissue through metabolic pathways, ionostatic control, and homeostatic clearance of neurotransmitters. Stress or trauma-associated impairment of these vital astrocytic functions contribute to the pathophysiological evolution of PTSD and may present therapeutic targets.

Vascular and blood-brain barrier-related changes underlie stress responses and resilience in female mice and depression in human tissue

Prevalence, symptoms, and treatment of depression suggest that major depressive disorders (MDD) present sex differences. Social stress-induced neurovascular pathology is associated with depressive symptoms in male mice; however, this association is unclear in females. Here, we report that chronic social and subchronic variable stress promotes blood-brain barrier (BBB) alterations in mood-related brain regions of female mice. Targeted disruption of the BBB in the female prefrontal cortex (PFC) induces anxiety- and depression-like behaviours. By comparing the endothelium cell-specific transcriptomic profiling of the mouse male and female PFC, we identify several pathways and genes involved in maladaptive stress responses and resilience to stress. Furthermore, we confirm that the BBB in the PFC of stressed female mice is leaky. Then, we identify circulating vascular biomarkers of chronic stress, such as soluble E-selectin. Similar changes in circulating soluble E-selectin, BBB gene expression and morphology can be found in blood serum and postmortem brain samples from women diagnosed with MDD. Altogether, we propose that BBB dysfunction plays an important role in modulating stress responses in female mice and possibly MDD.

Mechanisms affecting brain remodeling in depression: do all roads lead to impaired fibrinolysis?

Fibrinolysis occurs when plasminogen activators, such as tissue plasminogen activator (tPA), convert plasminogen to plasmin, which dissolves the fibrin clot. The proteolytic activity of tPA and plasmin is not restricted to fibrin degradation. In the extravascular space, these two proteases modify a variety of substrates other than fibrin, playing a crucial role in physiological and pathological tissue remodeling. In the brain, for example, tPA and plasmin mediate the conversion of brain-derived neurotrophic factor precursor (proBDNF) to mature brain-derived neurotrophic factor precursor (BDNF). Thus, the fibrinolytic system influences processes reported to be dysfunctional in depression, including neurogenesis, synaptic plasticity, and reward processing. The hypothesis that decreased fibrinolytic activity is an important element in the pathogenesis of depression is supported by the association between depression and increased levels of plasminogen activator inhibitor (PAI)-1, the main inhibitor of tPA. Also, various biochemical markers of depression induce PAI-1 synthesis, including hypercortisolism, hyperinsulinemia, hyperleptinemia, increased levels of cytokines, and hyperhomocysteinemia. Moreover, hypofibrinolysis provides a link between depression and emotional eating, binge eating, vegetarianism, and veganism. This paper discusses the role of reduced fibrinolytic activity in the bidirectional interplay between depression and its somatic manifestations and complications. It also reviews evidence that abnormal fibrinolysis links heterogeneous conditions associated with treatment-resistant depression. Understanding the role of hypofibrinolysis in depression may open new avenues for its treatment.

Serum plasminogen activator inhibitor-1 levels in patients with major depressive disorder vs. healthy controls: a systematic review and meta-analysis

INTRODUCTION

Major depressive disorder (MDD) is a severe mental health condition that affects millions of people worldwide. Etiologically, several factors may play a role in its development. Previous studies have reported elevated plasminogen activator inhibitor-1 (PAI-1) levels in patients with depression, suggesting that PAI-1 levels might be linked to the etiology of MDD.

METHODS

We systematically searched the following online databases: MEDLINE, Scopus, and Web of Science up to September 10, 2020, to identify studies in which PAI-1 levels were reported in subjects with MDD. Subsequently we used RevMan 5.3 to perform a meta-analysis of data extracted from the included studies using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and PICO criteria for the search and analysis.

RESULTS

Six studies that reported mean ± standard deviation (SD) were included in the analysis, with a total of 507 MDD patients and 3,453 controls. The overall standardized mean difference (SMD) was 0.27 (95% confidence interval [95% CI] 0.01-0.53). PAI-1 serum levels were 0.27 SDs higher in MDD patients than in controls. The test for overall effect was significant (z = 2.04, p = 0.04). Substantial heterogeneity was detected among the studies, demonstrated by the inconsistency test (I² = 72%) and the chi-square test (χ² = 18.32; p = 0.003).

CONCLUSIONS

This systematic review and meta-analysis showed that MDD might be related to elevated PAI-1 levels. We propose larger prospective clinical studies to further investigate this clinical correlation and validate the clinical significance of these observations.

PTSD as an Endothelial Disease: Insights From COVID-19

SARS-CoV-2 virus, the etiologic agent of COVID-19, has affected almost every aspect of human life, precipitating stress-related pathology in vulnerable individuals. As the prevalence rate of posttraumatic stress disorder in pandemic survivors exceeds that of the general and special populations, the virus may predispose to this disorder by directly interfering with the stress-processing pathways. The SARS-CoV-2 interactome has identified several antigens that may disrupt the blood-brain-barrier by inducing premature senescence in many cell types, including the cerebral endothelial cells. This enables the stress molecules, including angiotensin II, endothelin-1 and plasminogen activator inhibitor 1, to aberrantly activate the amygdala, hippocampus, and medial prefrontal cortex, increasing the vulnerability to stress related disorders. This is supported by observing the beneficial effects of angiotensin receptor blockers and angiotensin converting enzyme inhibitors in both posttraumatic stress disorder and SARS-CoV-2 critical illness. In this narrative review, we take a closer look at the virus-host dialog and its impact on the renin-angiotensin system, mitochondrial fitness, and brain-derived neurotrophic factor. We discuss the role of furin cleaving site, the fibrinolytic system, and Sigma-1 receptor in the pathogenesis of psychological trauma. In other words, learning from the virus, clarify the molecular underpinnings of stress related disorders, and design better therapies for these conditions. In this context, we emphasize new potential treatments, including furin and bromodomains inhibitors.

Proteolytic cleavage of proBDNF to mBDNF in neuropsychiatric and neurodegenerative diseases

Brain-derived neurotrophic factor (BDNF) is involved in pathophysiological mechanisms in neuropsychiatric diseases, including depression, anxiety, and schizophrenia (SZ), as well as neurodegenerative diseases like Parkinson's disease (PD) and Alzheimer's disease (AD). An imbalance or insufficient pro-brain-derived neurotrophic factor (proBDNF) transformation into mature BDNF (mBDNF) is potentially critical to the disease pathogenesis by impairing neuronal plasticity as suggested by results from many studies. Thus, promoting proBDNF transformation into mBDNF is therefore hypothesized as beneficial for the treatment of neuropsychiatric and neurodegenerative diseases. ProBDNF is proteolytically cleaved into the mBDNF by intracellular furin/proprotein convertases and extracellular proteases (plasmin/matrix metallopeptidases). This article reviews the mechanisms of the conversion of proBDNF to mBDNF and the research status of intracellular/extracellular proteolytic proteases for neuropsychiatric and neurodegenerative disorders.

Regulatory Mechanism of MicroRNA-30b on Neonatal Hypoxic-Ischemic Encephalopathy (HIE)

OBJECTIVE

This study is to investigate the role of microRNA (miR)-30b in the pathogenesis of hypoxic-ischemic encephalopathy (HIE) in neonates.

METHODS

Totally 26 cases of neonatal HIE were included in this study. The protein expression levels of CD26P and PAI-1 were detected with ELISA. Serum levels of miR-30b and PAI-1 mRNA was measured by quantitative real-time PCR. Human brain microvascular endothelial cells (HBMECs) were cultured under hypoxic condition, and the intracellular expression levels of miR-30b and PAI-1 were evaluated. Dual-luciferase reporter assay was performed to confirm the interaction between miR-30b and PAI-1.

RESULTS

Compared with the control group, both the mRNA and protein expression levels of PAI-1 in the serum were up-regulated in the neonates with HIE, together with up-regulated serum CD26P levels. However, the serum expression level of miR-30b was down-regulated in neonatal HIE. In hypoxia-induced HBMECs, the mRNA and protein expression levels of PAI-1 were significantly up-regulated, while the miR-30b expression level was significantly down-regulated. Dual-luciferase reporter assay showed that PAI-1 was the direct target of miR-30b.

CONCLUSION

Neonatal HIE is accompanied with abnormal platelet activation, significantly up-regulated serum PAI-1 expression levels, and down-regulated miR-30b expression. MiR-30b might regulate the disease pathogenesis and immune responses via modulating PAI-1.

Synergy between plasminogen activator inhibitor-1, α-synuclein, and neuroinflammation in Parkinson's disease

Parkinson's disease (PD) is a progressive degenerative nervous system disorder and is the second most common neurodegenerative disorder in the elderly population. The disease originates from the loss of dopamine-producing neurons in the substantia nigra in the brain, resulting in unregulated activity of the basal ganglia. Αlpha-synuclein (α-syn) is a protein found to aggregate in the substantia nigra region of patients with PD, forming Lewy Body inclusions; its aggregation may contribute to neuronal cell death in PD. This work hypothesizes about the synergistic relationship between α-syn aggregation and neuroinflammation to up-regulate expression of the serine protease inhibitor (serpin) plasminogen activator inhibitor-1 (PAI-1). The protease, plasmin, has been shown to cleave extracellular α-syn (including its monomeric, oligomeric, and fibrillary forms), resulting in less aggregation and Lewy Body formation. The zymogen plasminogen is converted to its active serine protease form, plasmin, either by tissue plasminogen activator (tPA) or by urokinase plasminogen activator (uPA) bound to urokinase receptor (uPAR). Both tPA and uPA/uPAR are inhibited by PAI-1. Thus, when PAI-1 levels increase, less plasmin is generated, which would lead to reduced proteolysis of α-syn. Expression of PAI-1 is increased both in inflammatory environments and in the presence of extracellular α-syn aggregates. This scenario suggests a pathological amplification loop: increased extracellular α-syn aggregation activates an inflammatory response from microglia and astrocytes, increasing PAI-1 levels, and decreasing the generation of plasmin. With reduced plasmin, less α-syn can be cleaved, and aggregation continues, sustaining the pathological process. Understanding this putative pathogenic loop could provide insight into the means by which neurodegeneration progresses in PD, and it may offer possible novel therapeutic strategies.

Increased expression of plasminogen activator inhibitor-1 (PAI-1) is associated with depression and depressive phenotype in C57Bl/6J mice

Plasminogen activator inhibitor 1 (PAI-1), which is elevated in numerous disease states, has been implicated as a stress-related protein involved in the pathogenesis of depression. We measured PAI-1 in the plasma of healthy and depressed individuals and assessed plasminogen activator (PA) expression and regulation by PAI-1 in cultured normal human astrocytes (NHA). Elevated plasma PAI-1 levels were found in depressed patients. Brain tissues from depressed individuals also showed stronger expression of hippocampal PAI-1 by confocal imaging in comparison to healthy individuals. Using a lipopolysaccharide-induced inflammatory model of depression in mice, we measured PAI-1 in murine plasma and brain, by ELISA and immunohistochemistry, respectively. Similar elevations were seen in plasma but not in brain homogenates of mice exposed to LPS. We further correlated the findings with depressive behavior. Ex vivo experiments with NHA treated with proinflammatory cytokines implicated in the pathogenesis of depression showed increased PAI-1 expression. Furthermore, these studies suggest that urokinase-type plasminogen activator may serve as an astrocyte PA reservoir, able to promote cleavage of brain-derived neurotrophic factor (BDNF) during stress or inflammation. In summary, our findings confirm that derangements of PAI-1 variably occur in the brain in association with the depressive phenotype. These derangements may impede the availability of active, mature (m)BDNF and thereby promote a depressive phenotype.

Plasminogen Activator Inhibitor-1 (PAI-1) deficiency predisposes to depression and resistance to treatments

Major depressive disorder (MDD) is one of the most frequent psychiatric illnesses, leading to reduced quality of life, ability to work and sociability, thus ranking among the major causes of disability and morbidity worldwide. To date, genetic and environmental determinants of MDD remain mostly unknown. Here, we investigated whether and how the Plasminogen Activator Inhibitor-1 (PAI-1) may contribute to MDD. We first examined the phenotype of PAI-1 knockout (PAI-1−/−) and wild-type (PAI-1+/+) male mice with a range of behavioral tests assessing depressive-like behaviors (n = 276). We next investigated the mechanisms relating PAI-1 to MDD using molecular, biochemical and pharmacological analyzes. We demonstrate here that PAI-1 plays a key role in depression by a mechanism independent of the tissue-type Plasminogen Activator (tPA) – Brain-Derived Neurotrophic Factor (BDNF) axis, but associated with impaired metabolisms of serotonin and dopamine. Our data also reveal that PAI-1 interferes with therapeutic responses to selective serotonin reuptake inhibitors (escitalopram, fluoxetine). We thus highlight a new genetic preclinical model of depression, with the lack of PAI-1 as a factor of predisposition to MDD. Altogether, these original data reveal that PAI-1 should be now considered as a key player of MDD and as a potential target for the development of new drugs to cure depressive patients resistant to current treatments.

Altered fibrinolytic system in rat models of depression and patients with first-episode depression

Tissue plasminogen activator (tPA) is a serine protease involved in cleavage of neurotrophic factors. In addition, tPA and neuroserpin can also directly bind to low density lipoprotein receptor-related protein 1 (LRP1), promoting neurogenesis and neurite outgrowth. Given both the cleavage and non-cleavage actions of the fibrinolytic system are crucial in neurological functions, the present study, for the first time, systematically detected the changes of fibrinolytic system factors in rats exposed to chronic unpredictable mild stress (CUMS) or lipopolysaccharide (LPS) and patients with depression. In general, our data demonstrated that both CUMS and LPS reduced tPA but elevated plasminogen activator inhibitor-1 (PAI-1; SERPINE1) mRNA expression. Intriguingly, decreased expression of neuroserpin and LRP1 was also observed in rats exposed to CUMS or LPS. The down-regulated neuroserpin and LRP1 signaling were confirmed by western blotting and immunoflurence data. Likewise, elevated PAI-1 but a significant reduction of neuroserpin and LRP1 mRNA expression were observed in the peripheral blood mononuclear cells (PBMCs) of patients with first-episode depression, and the mRNA levels of PAI-1, neuroserpin and LRP1 were correlated with the Beck Depression inventory (BDI) scores, further strengthening the clinical significance and involvement of the fibrinolytic system in depression. Collectively, the present study demonstrated the alterations of fibrinolytic system in stressed and inflamed brain and in patients with first-episode depression, firstly showing that not only the cleavage actions, but also the non-cleavage actions of the system may play an essential role in the development of depression.

Immune and metabolic alterations in first episode psychosis (FEP) patients

The molecular underpinnings associated to first episode psychosis (FEP) remains to be elucidated, but compelling evidence supported an association of FEP with blood alterations in biomarkers related to immune system, growth factors and metabolism regulators. Many of these studies have not been already confirmed in larger samples or have not considered the FEP diagnostic subgroups. In order to identify biochemical signatures of FEP, the serum levels of the growth factors BDNF and VEGF, the immune regulators IL-1RA, IL-6, IL-10 and IL-17, RANTES/CCL5, MIP-1b/CCL4, IL-8 and the metabolic regulators C-peptide, ghrelin, GIP, GLP-1, glucagon, insulin, leptin, PAI-1, resistin and visfatin were analysed in 260 subjects collected in the GET UP project. The results indicated an increase of MIP-1b/CCL4, VEGF, IL-6 and PAI-1, while IL-17, ghrelin, glucagon and GLP-1 were decreased in the whole sample of FEP patients (p < 0.01 for all markers except for PAI-1 p < 0.05). No differences were evidenced for these markers among the diagnostic groups that constitute the FEP sample, whereas IL-8 is increased only in patients with a diagnosis of affective psychosis. The principal component analysis (PCA) and variable importance analysis (VIA) indicated that MIP-1b/CCL4, ghrelin, glucagon, VEGF and GLP-1 were the variables mostly altered in FEP patients. On the contrary, none of the analysed markers nor a combination of them can discriminate between FEP diagnostic subgroups. These data evidence a profile of immune and metabolic alterations in FEP patients, providing new information on the molecular mechanism associated to the psychosis onset for the development of preventive strategies and innovative treatment targets.

Plasminogen Activator Inhibitor-1 Is a Marker and a Mediator of Senescence

PAI-1 (plasminogen activator inhibitor-1) is a member of the evolutionarily conserved serine protease inhibitor family and a potent and rapid-acting inhibitor of both of the mammalian plasminogen activators. Organismal homeostasis requires physiological levels of endogenous PAI-1, and increased PAI-1 production guides the onset and progression of numerous human diseases and contributes to the multimorbidity of aging. Both chronological and stress-induced accelerated aging are associated with cellular senescence and accompanied by marked increases in PAI-1 expression in tissues. Recent studies suggest that PAI-1 is not only a marker but also a key mediator of cellular senescence and organismal aging. Here, we review the significance of PAI-1 as a bonafide marker, as well as a critical mediator, of cellular senescence associated with aging and aging-related pathologies.

The serum protein levels of the tPA-BDNF pathway are implicated in depression and antidepressant treatment

Evidence demonstrates that brain-derived neurotrophic factor (BDNF) has a pivotal role in the pathogenesis of major depressive disorder (MDD). Precursor-BDNF (proBDNF) and mature BDNF (mBDNF) have opposing biological effects in neuroplasticity, and the tissue-type plasminogen activator (tPA)/plasmin system is crucial in the cleavage processing of proBDNF to mBDNF. However, very little is known about the role of the tPA-BDNF pathway in MDD. We examined serum protein concentrations in the tPA-BDNF pathway, including tPA, BDNF, tropomyosin receptor kinase B (TrkB), proBDNF and p75NTR, obtained from 35 drug-free depressed patients before and after 8 weeks of escitalopram (mean 12.5 mg per day) or duloxetine (mean 64 mg per day) treatment and 35 healthy controls using sandwich ELISA (enzyme-linked immunosorbent assay) methods. Serum tPA and BDNF and the ratio of BDNF/proBDNF were significantly lower in the MDD patients than in controls, whereas TrkB, proBDNF and its receptor p75NTR were higher. After 8 weeks of treatment, tPA, BDNF and proBDNF and the BDNF/proBDNF ratio were reversed, but p75NTR was higher than baseline, and TrkB was not significantly changed. tPA, BDNF, TrkB, proBDNF and p75NTR all yielded fairly good or excellent diagnostic performance (area under the receiver operating characteristic curve (AUC) >0.8 or 0.9). Combination of these five proteins demonstrated much better diagnostic effectiveness (AUC: 0.977) and adequate sensitivity and specificity of 88.1% and 92.7%, respectively. Our results suggest that the tPA-BDNF lysis pathway may be implicated in the pathogenesis of MDD and the mechanisms underlying antidepressant therapeutic action. The combination of tPA, BDNF, TrkB, proBDNF and p75NTR may provide a diagnostic biomarker panel for MDD.