Biomarkers of intestinal permeability and blood-brain barrier permeability in adolescents with major depressive disorder

Constipation is associated with emotional and cognitive impairment in patients with Parkinson's disease: a clinical and brain functional study

OBJECTIVE

Constipation frequently occurs in patients with Parkinson's disease (PD) and may be related to cognitive and emotional disorders. The aim of this study is to investigate the clinical and brain functional characteristics of patients with PD presenting with constipation.

METHODS

The motor and non-motor symptoms of patients with PD were evaluated, and a resting-state functional magnetic resonance imaging (RS-fMRI) study was conducted based on propensity score matching. Alterations in brain function were analyzed using regional homogeneity (ReHo) and functional connectivity (FC).

RESULTS

Compared with patients without constipation (PD-NC group), patients with constipation (PD-C group) had more serious motor and non-motor symptoms (including cognitive and emotional disorders along with visual hallucinations). Further, emotional and cognitive disorders were correlated with the occurrence of constipation in patients with PD. Compared with the PD-NC group, the PD-C group showed a reduced ReHo of the right insula and bilateral orbitofrontal cortex (OFC), increased ReHo of the left postcentral gyrus, and enhanced FC between the right OFC and the left middle temporal gyrus (MTG) and middle occipital gyrus (MOG). Additionally, the activity of the OFC and insula was significantly correlated with the constipation, mood, and cognitive levels of patients with PD.

CONCLUSIONS

Constipation in patients with PD is closely related to emotional and cognitive impairments, abnormal activity and FC of brain regions such as the right insula and bilateral OFC may play an important role in this.

Glial Markers of Suicidal Behavior in the Human Brain-A Systematic Review of Postmortem Studies

Suicide is a major public health priority, and its molecular mechanisms appear to be related to glial abnormalities and specific transcriptional changes. This study aimed to identify and synthesize evidence of the relationship between glial dysfunction and suicidal behavior to understand the neurobiology of suicide. As of 26 January 2024, 46 articles that met the inclusion criteria were identified by searching PubMed and ISI Web of Science. Most postmortem studies, including 30 brain regions, have determined no density or number of total Nissl-glial cell changes in suicidal patients with major psychiatric disorders. There were 17 astrocytic, 14 microglial, and 9 oligodendroglial studies using specific markers of each glial cell and further on their specific gene expression. Those studies suggest that astrocytic and oligodendroglial cells lost but activated microglia in suicides with affective disorder, bipolar disorders, major depression disorders, or schizophrenia in comparison with non-suicided patients and non-psychiatric controls. Although the data from previous studies remain complex and cannot fully explain the effects of glial cell dysfunction related to suicidal behaviors, they provide risk directions potentially leading to suicide prevention.

Unraveling the Role of the Blood-Brain Barrier in the Pathophysiology of Depression: Recent Advances and Future Perspectives

Depression is a highly prevalent psychological disorder characterized by persistent dysphoria, psychomotor retardation, insomnia, anhedonia, suicidal ideation, and a remarkable decrease in overall well-being. Despite the prevalence of accessible antidepressant therapies, many individuals do not achieve substantial improvement. Understanding the multifactorial pathophysiology and the heterogeneous nature of the disorder could lead the way toward better outcomes. Recent findings have elucidated the substantial impact of compromised blood-brain barrier (BBB) integrity on the manifestation of depression. BBB functions as an indispensable defense mechanism, tightly overseeing the transport of molecules from the periphery to preserve the integrity of the brain parenchyma. The dysfunction of the BBB has been implicated in a multitude of neurological disorders, and its disruption and consequent brain alterations could potentially serve as important factors in the pathogenesis and progression of depression. In this review, we extensively examine the pathophysiological relevance of the BBB and delve into the specific modifications of its components that underlie the complexities of depression. A particular focus has been placed on examining the effects of peripheral inflammation on the BBB in depression and elucidating the intricate interactions between the gut, BBB, and brain. Furthermore, this review encompasses significant updates on the assessment of BBB integrity and permeability, providing a comprehensive overview of the topic. Finally, we outline the therapeutic relevance and strategies based on BBB in depression, including COVID-19-associated BBB disruption and neuropsychiatric implications. Understanding the comprehensive pathogenic cascade of depression is crucial for shaping the trajectory of future research endeavors.

Lipopolysaccharide, VE-cadherin, HMGB1, and HIF-1α levels are elevated in the systemic circulation in chronic migraine patients with medication overuse headache: evidence of leaky gut and inflammation

OBJECTIVE

Medication overuse headache (MOH) was recently shown to be associated with leaky gut in rodents. We aimed to investigate whether chronic migraine (CM) patients with MOH have elevated lipopolysaccharide levels and inflammatory molecules in blood circulation.

MATERIALS AND METHODS

The study included women participants (40 CM patients with NSAID overuse headache, 35 episodic migraine (EM) patients, and 20 healthy non-headache sufferers). Migraine duration, monthly migraine headache days, MigSCog, HADS-D, HADS-A, and HIT-6 scores were recorded. Serum samples were collected to measure circulating LPS, LPS binding protein (LBP), tight junction protein occludin, adherens junction protein vascular endothelial cadherin (VE-cadherin), CGRP, HMGB1, HIF-1α, IL-6, and IL-17 levels.

RESULTS

Serum LPS, VE-Cadherin, CGRP, HIF-1α, and IL-6 levels were significantly higher in the CM + MOH group compared to the EM group and healthy controls while serum LBP and HMGB1 were higher in the CM + MOH group compared to healthy controls. IL-17 and occludin levels were comparable between the three groups. Serum HMGB1 levels in EM patients were higher compared to the control group. Mig-SCog and HIT-6 scores were higher in the CM + MOH group compared to EM patients. HADS-A and HADS-D scores were significantly higher in the CM + MOH group compared to EM patients and healthy controls, and they were also higher in EM patients compared to healthy subjects. LPS levels were correlated with VE-cadherin and occludin levels. The number of monthly migraine headache days was positively correlated with serum LPS, HIF-1α, VE-cadherin, and IL-6 levels, HADS-A, HADS-D, HIT-6, and MigSCog scores.

CONCLUSION

We have evidence for the first time that CM + MOH is associated with elevated serum LPS and LBP levels suggestive of LPS leak into the systemic circulation. Higher levels of nociceptive and/or pro-inflammatory molecules such as HMGB1, HIF-1α, IL-6, and CGRP may play a role in trigeminal sensitization and neurobiology of MOH. Intestinal hyperpermeability and consequent inflammatory response should be considered as a potential contributory factor in patients with MOH.

Association of Plasma Claudin-5 with Age and Alzheimer Disease

The blood-brain barrier (BBB) plays pivotal roles in synaptic and neuronal functioning by sealing the space between adjacent microvascular endothelial cells. BBB breakdown is present in patients with mild cognitive impairment (MCI) or Alzheimer disease (AD). Claudin-5 (CLDN-5) is a tetra-spanning protein essential for sealing the intercellular space between adjacent endothelial cells in the BBB. In this study, we developed a blood-based assay for CLDN-5 and investigated its diagnostic utility using 100 cognitively normal (control) subjects, 100 patients with MCI, and 100 patients with AD. Plasma CLDN-5 levels were increased in patients with AD (3.08 ng/mL) compared with controls (2.77 ng/mL). Plasma levels of phosphorylated tau (pTau181), a biomarker of pathological tau, were elevated in patients with MCI or AD (2.86 and 4.20 pg/mL, respectively) compared with control subjects (1.81 pg/mL). In patients with MCI or AD, plasma levels of CLDN-5-but not pTau181-decreased with age, suggesting some age-dependent BBB changes in MCI and AD. These findings suggest that plasma CLDN-5 may a potential biochemical marker for the diagnosis of AD.

Decoding the role of the gut microbiome in gut-brain axis, stress-resilience, or stress-susceptibility: A review

Increased exposure to stress is associated with stress-related disorders, including depression, anxiety, and neurodegenerative conditions. However, susceptibility to stress is not seen in every individual exposed to stress, and many of them exhibit resilience. Thus, developing resilience to stress could be a big breakthrough in stress-related disorders, with the potential to replace or act as an alternative to the available therapies. In this article, we have focused on the recent advancements in gut microbiome research and the potential role of the gut-brain axis (GBA) in developing resilience or susceptibility to stress. There might be a complex interaction between the autonomic nervous system (ANS), immune system, endocrine system, microbial metabolites, and bioactive lipids like short-chain fatty acids (SCFAs), neurotransmitters, and their metabolites that regulates the communication between the gut microbiota and the brain. High fiber intake, prebiotics, probiotics, plant supplements, and fecal microbiome transplant (FMT) could be beneficial against gut dysbiosis-associated brain disorders. These could promote the growth of SCFA-producing bacteria, thereby enhancing the gut barrier and reducing the gut inflammatory response, increase the expression of the claudin-2 protein associated with the gut barrier, and maintain the blood-brain barrier integrity by promoting the expression of tight junction proteins such as claudin-5. Their neuroprotective effects might also be related to enhancing the expression of brain-derived neurotrophic factor (BDNF) and glucagon-like peptide (GLP-1). Further investigations are needed in the field of the gut microbiome for the elucidation of the mechanisms by which gut dysbiosis contributes to the pathophysiology of neuropsychiatric disorders.

Neuropsychiatric adverse effects from CFTR modulators deserve a serious research effort

PURPOSE OF REVIEW

This review highlights the problem of neuropsychiatric adverse effects (AEs) associated with elexacaftor/tezacaftor/ivacaftor (ETI), current suboptimal mitigation approaches, a novel testable mechanistic hypothesis, and potential solutions requiring further research.

RECENT FINDINGS

Studies show that a minority of persons with cystic fibrosis (PwCF) initiating cystic fibrosis transmembrane conductance regulator (CFTR) modulators experience neuropsychiatric AEs including worsening mood, cognition, anxiety, sleep, and suicidality. The GABA-A receptor is a ligand-gated chloride channel, and magnetic resonance spectroscopy neuroimaging studies have shown that reduced GABA expression in rostral anterior cingulate cortex is associated with anxiety and depression. Recent research details the impact of peripheral inflammation and the gut-brain axis on central neuroinflammation. Plasma ETI concentrations and sweat chloride have been evaluated in small studies of neuropsychiatric AEs but not validated to guide dose titration or correlated with pharmacogenomic variants or safety/efficacy.

SUMMARY

Although ETI is well tolerated by most PwCF, some experience debilitating neuropsychiatric AEs. In some cases, these AEs may be driven by modulation of CFTR and chloride transport within the brain. Understanding biological mechanisms is a critical next step in identifying which PwCF are likely to experience AEs, and in developing evidence-based strategies to mitigate them, while retaining modulator efficacy.

Serum Zonula Occludens-1 and Claudin-5 Levels in Patients with Insomnia Disorder: A Pilot Study

Purpose

This research aimed to investigate serum Zonula occludens-1 (ZO-1) and Claudin-5 (CLDN5) levels to show whether or not their eventual changes in patients with insomnia disorder could have etiopathogenetic importance. There was no research investigating serum ZO-1 and CLDN5 concentrations in insomnia disorder.

Patients and Methods

This study included 60 insomnia disorder patients and 45 normal controls. None of the patients received drugs for insomnia. The patients completed Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Index (PSQI), and Polysomnography (PSG) to score the insomnia disorder symptoms. Venous blood samples were collected, and serum ZO-1 and claudin-5 levels were analyzed by enzyme-linked immunosorbent assay (ELISA).

Results

Serum ZO-1 level was significantly higher without a significant difference between age, sex, and body mass index, whereas the difference in serum claudin-5 level between the two groups was not statistically significant. In addition, ZO-1 levels were positively correlated with ISI and PSQI and negatively with N1 and N1_perc. We also demonstrated a positive correlation between the levels of CLDN5 and HAMA, and a negative correlation with total sleep time (TST), N1 and N1_perc.

Conclusion

Our findings suggest an association between these intestinal and brain endothelial permeability markers and insomnia disorders. However, these remain modest and preliminary and need more extensive studies, including long-term follow-up populations and involving gut microbes, to further validate and explore the mechanisms involved.

Identification of Plasma Inflammatory Markers of Adolescent Depression Using the Olink Proteomics Platform

Purpose

The quality of life of worldwide adolescents has been seriously affected by depression. Notably, the inflammatory response is closely associated with the pathophysiology of depression. The present study applied a novel targeted proteomics technology, Olink proximity extension assay (PEA), to profile circulating immune-related proteins in adolescents with depression.

Methods

In the present study, the expression levels of 92 inflammation-related proteins were compared between adolescents with depression (ADs) (n=15) and healthy controls (HCs) (n=15), using the OLINK PEA inflammation panel. We further validated 5 top proteins that were identified through KEGG and GO analyses between 40 HCs and 50 ADs, including CCL4, CXCL5, CXCL6, CXCL11, and IL-18 using enzyme linked immunosorbent assay (ELISA).

Results

We identified 13 differentially expressed proteins between the two cohorts, including 5 up-regulated and 8 down-regulated proteins. Among them, the TRAIL protein levels were significantly negatively correlated with the HAMA-14 score (r=-0.538, p= 0.038), and the levels of transforming growth factor α (TGF-α) were significantly associated with a change in appetite (r = -0.658, p = 0.008). After validation by ELISA, CCL4, CXCL5, CXCL11, and IL-18 showed significant changes between ADs and HCs (p < 0.05), while CXCL6 showed an up-regulated tendency in ADs (p=0.0673). The pooled diagnostic efficacy (area under the curve [AUC]) of these five inflammation markers in clinical diagnosis for adolescent depression was 0.819 (95% CI: 0.735-0.904).

Conclusion

We report a number of inflammation-related plasma biomarkers, which uncover a potential involvement of chemokines, cytokines, and cytokine receptors in adolescent depression. Their roles in the pathophysiology of depression need to be further elucidated.

The Intertwining Roads between Psychological Distress and Gut Microbiota in Inflammatory Bowel Disease

Inflammatory bowel disease represents one of the most life-altering gastrointestinal pathologies, with its multifactorial nature and unclear physiopathology. The most relevant clinical forms, ulcerative colitis and Crohn's disease, clinically manifest with mild to severe flares and remission periods that alter the patient's social, familial and professional integration. The chronic inflammatory activity of the intestinal wall determines severe modifications of the local environment, such as dysbiosis, enteric endocrine, nervous and immune system disruptions and intestinal wall permeability changes. These features are part of the gastrointestinal ecosystem that modulates the bottom-to-top signaling to the central nervous system, leading to a neurobiologic imbalance and clinical affective and/or behavioral symptoms. The gut-brain link is a bidirectional pathway and psychological distress can also affect the central nervous system, which will alter the top-to-bottom regulation, leading to possible functional digestive symptoms and local inflammatory responses. In the middle of this neuro-gastrointestinal system, the microbiome is a key player, as its activities offer basic functional support for both relays. The present article presents current scientific information that links the pathophysiology and clinical aspects of inflammatory bowel disease and psychiatric symptomatology through the complex mechanism of the gut-brain axis and the modulatory effects of the gut microbiota.

Dietary Flaxseed and Flaxseed Oil Differentially Modulate Aspects of the Microbiota Gut-Brain Axis Following an Acute Lipopolysaccharide Challenge in Male C57Bl/6 Mice

The microbiota gut-brain axis (mGBA) is an important contributor to mental health and neurological and mood disorders. Lipopolysaccharides (LPS) are endotoxins that are components of Gram-negative bacteria cell walls and have been widely shown to induce both systemic and neuro-inflammation. Flaxseed (Linum usitatissimum) is an oilseed rich in fibre, n3-poly-unsaturated fatty acid (alpha-linolenic acid (ALA)), and lignan, secoisolariciresinol diglucoside, which all can induce beneficial effects across varying aspects of the mGBA. The objective of this study was to determine the potential for dietary supplementation with flaxseed or flaxseed oil to attenuate LPS-induced inflammation through modulation of the mGBA. In this study, 72 5-week-old male C57Bl/6 mice were fed one of three isocaloric diets for 3 weeks: (1) AIN-93G basal diet (BD), (2) BD + 10% flaxseed (FS), or (3) BD + 4% FS oil (FO). Mice were then injected with LPS (1 mg/kg i.p) or saline (n = 12/group) and samples were collected 24 h post-injection. Dietary supplementation with FS, but not FO, partially attenuated LPS-induced systemic (serum TNF-α and IL-10) and neuro-inflammation (hippocampal and/or medial prefrontal cortex IL-10, TNF-α, IL-1β mRNA expression), but had no effect on sickness and nest-building behaviours. FS-fed mice had enhanced fecal microbial diversity with increased relative abundance of beneficial microbial groups (i.e., Lachnospiraceae, Bifidobacterium, Coriobacteriaceae), reduced Akkermansia muciniphila, and increased production of short-chain fatty acids (SCFAs), which may play a role in its anti-inflammatory response. Overall, this study highlights the potential for flaxseed to attenuate LPS-induced inflammation, in part through modulation of the intestinal microbiota, an effect which may not be solely driven by its ALA-rich oil component.

Fecal and Circulating Biomarkers for the Non-Invasive Assessment of Intestinal Permeability

The study of intestinal permeability is gaining growing interest due to its relevance in the onset and progression of several gastrointestinal and non-gastrointestinal diseases. Though the involvement of impaired intestinal permeability in the pathophysiology of such diseases is recognized, there is currently a need to identify non-invasive biomarkers or tools that are able to accurately detect alterations in intestinal barrier integrity. On the one hand, promising results have been reported for novel in vivo methods based on paracellular probes, i.e., methods that can directly assess paracellular permeability and, on the other hand, on fecal and circulating biomarkers able to indirectly assess epithelial barrier integrity and functionality. In this review, we aimed to summarize the current knowledge on the intestinal barrier and epithelial transport pathways and to provide an overview of the methods already available or currently under investigation for the measurement of intestinal permeability.

Intestinal permeability and its significance in psychiatric disorders - a narrative review and future perspectives

The topic of increased intestinal permeability and its impact on the human body is. increasingly being addressed by researchers. It is associated with disruption of the. intestinal barrier, leading to the "leaky gut" syndrome. This can be assessed by. classical methods, determining the concentration of orally administered tracer. molecules in urine or by using biomarkers such as LPS, LBP or zonulin in blood. plasma. The presence of bacterial endotoxins in the body causes inflammation. In this. article, we review research on increased intestinal permeability in psychiatric illness. mood disorders, schizophrenia, alcohol dependence, anxiety disorders,. neurodegenerative and neurodevelopmental disorders. The results of the studies used. to assess intestinal permeability in different disease entities are presented. Possible. mechanisms for these interactions are the effects of chronic, low-grade inflammation. on the human brain, causing interruption of the brain blood barrier and dysfunction of. astrocytes and microglia. This affects brain function by reducing the number of. dopaminergic neurons, disrupting tryptophan metabolism and altering the amount of. GABA and glutamate. The links and mechanisms found may, in the future, allow earlier. detection of diseases and their targeted treatment.

Zonulin as a Potential Therapeutic Target in Microbiota-Gut-Brain Axis Disorders: Encouraging Results and Emerging Questions

The relationship between dysbiosis and central nervous diseases has been proved in the last 10 years. Microbial alterations cause increased intestinal permeability, and the penetration of bacterial fragment and toxins induces local and systemic inflammatory processes, affecting distant organs, including the brain. Therefore, the integrity of the intestinal epithelial barrier plays a central role in the microbiota-gut-brain axis. In this review, we discuss recent findings on zonulin, an important tight junction regulator of intestinal epithelial cells, which is assumed to play a key role in maintaining of the blood-brain barrier function. In addition to focusing on the effect of microbiome on intestinal zonulin release, we also summarize potential pharmaceutical approaches to modulate zonulin-associated pathways with larazotide acetate and other zonulin receptor agonists or antagonists. The present review also addresses the emerging issues, including the use of misleading nomenclature or the unsolved questions about the exact protein sequence of zonulin.