TNF-α, IL-6 and hsCRP in patients with melancholic, atypical and anxious depression: an antibody array analysis related to somatic symptoms

Gut-Brain Axis and Neuroinflammation: The Role of Gut Permeability and the Kynurenine Pathway in Neurological Disorders

The increasing prevalence of neurological disorders such as Alzheimer's, Parkinson's, and multiple sclerosis presents a significant global health challenge. Despite extensive research, the precise mechanisms underlying these conditions remain elusive, with current treatments primarily addressing symptoms rather than root causes. Emerging evidence suggests that gut permeability and the kynurenine pathway are involved in the pathogenesis of these neurological conditions, offering promising targets for novel therapeutic and preventive strategies. Gut permeability refers to the intestinal lining's ability to selectively allow essential nutrients into the bloodstream while blocking harmful substances. Various factors, including poor diet, stress, infections, and genetic predispositions, can compromise gut integrity, leading to increased permeability. This condition facilitates the translocation of toxins and bacteria into systemic circulation, triggering widespread inflammation that impacts neurological health via the gut-brain axis. The gut-brain axis (GBA) is a complex communication network between the gut and the central nervous system. Dysbiosis, an imbalance in the gut microbiota, can increase gut permeability and systemic inflammation, exacerbating neuroinflammation-a key factor in neurological disorders. The kynurenine pathway, the primary route for tryptophan metabolism, is significantly implicated in this process. Dysregulation of the kynurenine pathway in the context of inflammation leads to the production of neurotoxic metabolites, such as quinolinic acid, which contribute to neuronal damage and the progression of neurological disorders. This narrative review highlights the potential and progress in understanding these mechanisms. Interventions targeting the kynurenine pathway and maintaining a balanced gut microbiota through diet, probiotics, and lifestyle modifications show promise in reducing neuroinflammation and supporting brain health. In addition, pharmacological approaches aimed at modulating the kynurenine pathway directly, such as inhibitors of indoleamine 2,3-dioxygenase, offer potential avenues for new treatments. Understanding and targeting these interconnected pathways are crucial for developing effective strategies to prevent and manage neurological disorders.

Inflammatory biomarkers in depression: scoping review

BACKGROUND

Inflammation is increasingly recognised as a fundamental component of the pathophysiology of major depressive disorder (MDD), with a variety of inflammatory biomarkers playing pivotal roles. These markers are closely linked to both the severity of symptoms and the responsiveness to treatments in MDD.

AIMS

This scoping review aims to explore the scientific literature investigating the complex relationships between inflammatory biomarkers and depression, by identifying new studies and critical issues in current research.

METHOD

Following the PRISMA Extension for Scoping Reviews guidelines, we systematically searched databases including PubMed, Scopus, PsycINFO, Open Grey and Cochrane Library. Our search focused on articles published from 1 January 2020 to 1 May 2024. We included studies evaluating inflammatory biomarkers in adult patients with MDD, utilising observational and randomised controlled trial designs, and review studies.

RESULTS

Our analysis examined 44 studies on the complex interplay between inflammation and its multiple effects on MDD. Significant associations between specific inflammatory biomarkers and depression severity were found, requiring cautious interpretation. We also highlight several methodological limitations in the current studies, which warrant caution in directly applying these findings to clinical practice. However, identified methodologies show potential for using these biomarkers as diagnostic tools or therapeutic targets, including anti-inflammatory interventions.

CONCLUSIONS

The findings emphasise the need for sophisticated, integrative research to understand inflammation's role in MDD. Future studies should identify specific biomarker panels for diagnosing depression and bridging peripheral biomarker measurements with central neuroinflammatory processes, leading to better diagnostic and treatment strategies.

The Kynurenine Pathway in Gut Permeability and Inflammation

The gut-brain axis (GBA) is a crucial communication network linking the gastrointestinal (GI) tract and the central nervous system (CNS). The gut microbiota significantly influences metabolic, immune, and neural functions by generating a diverse array of bioactive compounds that modulate brain function and maintain homeostasis. A pivotal mechanism in this communication is the kynurenine pathway, which metabolises tryptophan into various derivatives, including neuroactive and neurotoxic compounds. Alterations in gut microbiota composition can increase gut permeability, triggering inflammation and neuroinflammation, and contributing to neuropsychiatric disorders. This review elucidates the mechanisms by which changes in gut permeability may lead to systemic inflammation and neuroinflammation, with a focus on the kynurenine pathway. We explore how probiotics can modulate the kynurenine pathway and reduce neuroinflammation, highlighting their potential as therapeutic interventions for neuropsychiatric disorders. The review integrates experimental data, discusses the balance between neurotoxic and neuroprotective kynurenine metabolites, and examines the role of probiotics in regulating inflammation, cognitive development, and gut-brain axis functions. The insights provided aim to guide future research and therapeutic strategies for mitigating GI complaints and their neurological consequences.

Mental stress, atheroma, myocardial ischaemia and injury: the link is inflammation

Increasing observational and experimental trial data have shown that mental stress can lead to an increase in adverse clinical cardiovascular events. Mental stress affects the heart by inducing ischaemia and precipitating myocardial infarction (MI) or direct myocardial injury. Mental stress leads to systemic inflammation. Inflammation is known to cause rapid atheromatous plaque progression, instability and thrombosis-the classic type 1 MI. Inflammation can also lead to type 2 MI or myocarditis and injury. The published data linking systemic inflammation, mental stress and cardiovascular disease will be reviewed to establish the linkage between mind and heart, thereby highlighting the importance of holistically managing the patient, not only addressing separate organ systems. Finally, recent trial evidence showing the value of anti-inflammatory drugs in cardiovascular and mental conditions will be briefly considered.

Differentiating melancholic and non-melancholic depression via biological markers: A review

OBJECTIVES

Melancholia is a severe form of depression that is typified by greater genetic and biological influence, distinct symptomatology, and preferential response to physical treatment. This paper sought to broadly overview potential biomarkers of melancholia to benefit differential diagnosis, clinical responses and treatment outcomes. Given nuances in distinguishing melancholia as its own condition from other depressive disorder, we emphasised studies directly comparing melancholic to non-melancholic depression.

METHODS

A comprehensive literature search was conducted. Key studies were identified and summarised qualitatively.

RESULTS

105 studies in total were identified. These studies covered a wide variety of biomarkers, and largely fell into three domains: endocrinological (especially cortisol levels, particularly in response to the dexamethasone suppression test), neurological, and immunological (particularly inflammatory markers). Less extensive evidence also exists for metabolic, genetic, and cardiovascular markers.

CONCLUSIONS

Definitive conclusions were predominantly limited due to substantial heterogeneity in how included studies defined melancholia. Furthermore, this heterogeneity could be responsible for the between- and within-group variability observed in the candidate biomarkers that were examined. Therefore, clarifying these definitional parameters may help identify underlying patterns in biomarker expression to improve diagnostic and therapeutic precision for the depressive disorders.

Targeting the ferroptosis crosstalk: novel alternative strategies for the treatment of major depressive disorder

Depression is a major contributor to poor global health and disability, with a recently increasing incidence. Although drug therapy is commonly used to treat depression, conventional antidepressant drugs have several disadvantages, including slow onset, low response rates and severe adverse effects. Therefore, developing effective therapies for depression remains challenging. Although various aetiological theories of depression exist, the underlying mechanisms of depression are complex, and further research is crucial. Moreover, oxidative stress (OS)-induced lipid peroxidation has been demonstrated to trigger ferroptosis. Both OS and ferroptosis are pivotal mechanisms implicated in the pathogenesis of neurological disorders, and investigation of the mediators involved in these processes has emerged as a prominent and active research direction. One previous study revealed that regulatory proteins involved in ferroptosis are implicated in the pathogenesis of depression, and antidepressant drugs could reverse depressive symptoms by inhibiting ferroptosis in vivo, suggesting an important role of ferroptosis in the pathogenesis of depression. Hence, our current comprehensive review offers an up-to-date perspective on the intricate mechanisms involved, specifically concerning ferroptosis and OS in the context of depression, along with promising prospects for using molecular mediators to target ferroptosis. We delineate the key targets of molecular mediators involved in OS and ferroptosis implicated in depression, most notably reactive oxygen species and iron overload. Considering the pivotal role of OS-induced ferroptosis in the pathogenesis of neurological disorders, delving deeper into the underlying subsequent mechanisms will contribute significantly to the identification of novel therapeutic targets for depression.

Effect of postoperative application of esketamine on postoperative depression and postoperative analgesia in patients undergoing pancreatoduodenectomy: a randomized controlled trial protocol

BACKGROUND

Pancreatoduodenectomy (PD) is traumatic, difficult to perform, and has a high incidence of postoperative complications and perioperative mortality. Postoperative complications and pain occur frequently and seriously affect the psychological status of patients. Esketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has analgesic and antidepressant effects. In this study, we aim to investigate the effect of esketamine on postoperative depression and pain in patients undergoing PD.

METHODS/DESIGN

This prospective, single-center, randomized control trial will include 80 patients who will undergo elective PD. The patients will be randomly assigned to two groups: the experimental group that will receive esketamine (n = 40) and the control group (n = 40). In the esketamine group, the analgesic pump will be connected immediately after surgery. A solution of esketamine 1.5 mg/kg + sufentanil 2 µg/kg, diluted to 150 mL, will be administered continuously for 72 h at the background infusion and impact doses of 1 mL/h and 2 mL/time, respectively; the locking time will be 10 min. The control group will receive sufentanil 2 µg/kg that will be administered as per the esketamine group. The primary outcome will be the Hamilton Depression Scale (HAMD-17) score on the third day post-surgery (POD3). Secondary study indicators will include (1) visual analog scale (VAS) score and HAMD-17 score prior to surgery, immediately after entering the postanesthesia care unit (PACU) and 1, 2, 3, 4, and 5 days after surgery; (2) Richmond Agitation-Sedation Scale (RASS) score at 1, 2, 3, 4, and 5 days after surgery; (3) consumed doses of sufentanil and esketamine after surgery; (4) postoperative analgesia pump effective press times, rescue analgesia times, and rescue drug dosage, recording the number of rescue analgesia and rescue drug dosage at 6, 24, 48, and 72 h after the patient enters the PACU; (5) postoperative complications and adverse events; (6) postoperative hospital stay; (7) concentrations of brain-derived neurotrophic factor (BDNP), 5-hydroxytryptamine (5-HT), tumor necrosis factor (TNF-α) and interleukin-6, at 1, 3, and, 5 days post-surgery; and (8) the patient survival rate at 6 and 12 months post-surgery.

DISCUSSION

The study hypothesis is that the postoperative HAMD-17 and VAS scores, incidence of postoperative adverse reactions, and concentration of serum markers BDNP, 5-HT, TNF-α, and IL-6 in the experimental group will be lower than those in the control group.

TRIAL REGISTRATION

ClinicalTrials.gov ChiCTR2200066303. Registered on November 30, 2022.

PROTOCOL VERSION

1.0.

Causal associations between major depressive disorder and COVID-19

Background

We aimed to evaluate whether major depressive disorder (MDD) could aggravate the outcomes of coronavirus disease 2019 (COVID-19) or whether the genetic liability to COVID-19 could trigger MDD.

Aims

We aimed to assess bidirectional causal associations between MDD and COVID-19.

Methods

We performed genetic correlation and Mendelian randomisation (MR) analyses to assess potential associations between MDD and three COVID-19 outcomes. Literature-based network analysis was conducted to construct molecular pathways connecting MDD and COVID-19.

Results

We found that MDD has positive genetic correlations with COVID-19 outcomes (r_g: 0.10-0.15). Our MR analysis indicated that genetic liability to MDD is associated with increased risks of COVID-19 infection (odds ratio (OR)=1.05, 95% confidence interval (CI): 1.00 to 1.10, p=0.039). However, genetic liability to the three COVID-19 outcomes did not confer any causal effects on MDD. Pathway analysis identified a panel of immunity-related genes that may mediate the links between MDD and COVID-19.

Conclusions

Our study suggests that MDD may increase the susceptibility to COVID-19. Our findings emphasise the need to increase social support and improve mental health intervention networks for people with mood disorders during the pandemic.

Impact of depression on the quality of sleep and immune functions in patients with coronary artery disease

Background

The risk of major depressive disorder (MDD) and insomnia is higher in patients with coronary heart disease (CHD) than in the general population. In addition, immune inflammation may be a shared aetiological factor for mental disorders and CHD. However, it is unclear whether MDD is associated with poor sleep quality and cell-mediated immune function in patients with CHD.

Aims

This study investigated the impact of depression on sleep quality and cell-mediated immune functions in patients with CHD and examined discriminative factors in patients with CHD with and without MDD.

Methods

This cross-sectional retrospective study was conducted at the Zhejiang University School of Medicine affiliated with Sir Run Run Shaw Hospital. The study population consisted of 84 patients with CHD assigned to two groups based on their Hamilton Depression Rating Scale (HAMD) score (CHD with MDD (HAMD score of ≥10) vs without MDD). Subjective sleep quality, systemic inflammatory response and cell-mediated immune functions were assessed in patients with CHD with (n=50) and without (n=34) MDD using the Pittsburgh Sleep Quality Index (PSQI), routine blood tests and flow cytometry. The relationships between variables were ascertained using Pearson's product-moment, and linear discriminant analysis was used to explore the discriminative factors between groups.

Results

Patients with CHD with MDD had significantly poorer sleep quality than those without MDD (Z=-6.864, p<0.001). The Systemic Inflammation Index (SII) and CD4⁺/CD8⁺ T-cell ratios were higher in patients with CHD with MDD than in those without MDD (Z=-3.249, p=0.001). Patients with CHD with MDD had fewer CD3⁺CD8⁺ and CD3⁺ T cells (Z=3.422, p=0.001) than those without MDD (t=2.032, p=0.045). Furthermore, patients with CHD with MDD may be differentiated from those without MDD using the PSQI, SII and T-cell levels, as these variables correctly classified the depressed and non-depressed groups with an accuracy of 96.4%.

Conclusions

MDD may be responsible for poor sleep quality, increased cell-mediated immunity and SII in patients with CHD, which are discriminative factors for CHD in the depressive state. Clinicians should be aware of these interactions, as treatment for depressive symptoms may also improve CHD prognosis.