Tyrosine metabolism during interferon-alpha administration: association with fatigue and CSF dopamine concentrations

Mild exogenous inflammation blunts neural signatures of bounded evidence accumulation and reward prediction error processing in healthy male participants

BACKGROUND

Altered neural haemodynamic activity during decision making and learning has been linked to the effects of inflammation on mood and motivated behaviours. So far, it has been reported that blunted mesolimbic dopamine reward signals are associated with inflammation-induced anhedonia and apathy. Nonetheless, it is still unclear whether inflammation impacts neural activity underpinning decision dynamics. The process of decision making involves integration of noisy evidence from the environment until a critical threshold of evidence is reached. There is growing empirical evidence that such process, which is usually referred to as bounded accumulation of decision evidence, is affected in the context of mental illness.

METHODS

In a randomised, placebo-controlled, crossover study, 19 healthy male participants were allocated to placebo and typhoid vaccination. Three to four hours post-injection, participants performed a probabilistic reversal-learning task during functional magnetic resonance imaging. To capture the hidden neurocognitive operations underpinning decision-making, we devised a hybrid sequential sampling and reinforcement learning computational model. We conducted whole brain analyses informed by the modelling results to investigate the effects of inflammation on the efficiency of decision dynamics and reward learning.

RESULTS

We found that during the decision phase of the task, typhoid vaccination attenuated neural signatures of bounded evidence accumulation in the dorsomedial prefrontal cortex, only for decisions requiring short integration time. Consistent with prior work, we showed that, in the outcome phase, mild acute inflammation blunted the reward prediction error in the bilateral ventral striatum and amygdala.

CONCLUSIONS

Our study extends current insights into the effects of inflammation on the neural mechanisms of decision making and shows that exogenous inflammation alters neural activity indexing efficiency of evidence integration, as a function of choice discriminability. Moreover, we replicate previous findings that inflammation blunts striatal reward prediction error signals.

Accelerated aging in people living with HIV: The neuroimmune feedback model

People living with HIV (PLWH) experience earlier onset of aging-related comorbidities compared to their counterparts without HIV. This paper lays out a theoretical model to explain why PLWH experience accelerated aging. Briefly, the model is structured as follows. PLWH experience disproportionately heavy burdens of psychosocial stress across the life course. This psychosocial stress increases risks for depressive symptoms and problematic substance use. Depressive symptoms and problematic substance use interfere with long-term adherence to antiretroviral therapy (ART). Lower ART adherence, in turn, exacerbates the elevated systemic inflammation stemming from HIV infection. This inflammation increases risks for aging-related comorbidities. Systemic inflammation also reduces connectivity in the brain's central executive network (CEN), a large-scale brain network that is critical for coping with stressful circumstances. This reduced capacity for coping with stress leads to further increases in depressive symptoms and problematic substance use. Together, these changes form a neuroimmune feedback loop that amplifies the impact of psychosocial stress on aging-related comorbidities. In this paper, I review the existing evidence relevant to this model and highlight directions for future research.

Metabolomic Insight into Implications of Induction Chemotherapy Followed by Concomitant Chemoradiotherapy in Locally Advanced Head and Neck Cancer

The present study compares two groups of locally advanced patients with head and neck squamous cell carcinoma (LA-HNSCC) undergoing concurrent chemoradiotherapy (cCHRT), specifically those for whom it is a first-line treatment and those who have previously received induction chemotherapy (iCHT). The crucial question is whether iCHT is a serious burden during subsequent treatment for LA-HNSCC and how iCHT affects the tolerance to cCHRT. Of the 107 LA-HNSCC patients, 54 received cisplatin-based iCHT prior to cCHRT. The patients were clinically monitored at weekly intervals from the day before until the completion of the cCHRT. The 843 blood samples were collected and divided into two aliquots: for laboratory blood tests and for nuclear magnetic resonance (NMR) spectroscopy (a Bruker 400 MHz spectrometer). The NMR metabolites and the clinical parameters from the laboratory blood tests were analyzed using orthogonal partial least squares analysis (OPLS) and the Mann-Whitney U test (MWU). After iCHT, the patients begin cCHRT with significantly (MWU p-value < 0.05) elevated blood serum lipids, betaine, glycine, phosphocholine, and reticulocyte count, as well as significantly lowered NMR inflammatory markers, serine, hematocrit, neutrophile, monocyte, red blood cells, hemoglobin, and CRP. During cCHRT, a significant increase in albumin and psychological distress was observed, as well as a significant decrease in platelet, N-acetyl-cysteine, tyrosine, and phenylalanine, in patients who received iCHT. Importantly, all clinical symptoms (except the decreased platelets) and most metabolic alterations (except for betaine, serine, tyrosine, glucose, and phosphocholine) resolve until the completion of cCHRT. In conclusion, iCHT results in hematological toxicity, altered lipids, and one-carbon metabolism, as well as downregulated inflammation, as observed at the beginning and during cCHRT. However, these complications are temporary, and most of them resolve at the end of the treatment. This suggests that iCHT prior to cCHRT does not pose a significant burden and should be considered as a safe treatment option for LA-HNSCC.

Narrative Review: Pathogenesis of the Inflammatory Response and Intestinal Flora in Depression

Depression, as a common mental illness that is often accompanied by suicidal and homicidal behaviors, is one of the most important diseases in the medical field that requires urgent attention. The pathogenesis of depression is complex, and the current therapeutic drugs such as tricyclic antidepressants (TCAs), monoamine oxidase inhibitors, and secondary serotonin reuptake inhibitors have certain shortcomings. The inflammatory factor hypothesis, one of the pathogenesis of depression, suggests that inflammatory response is a key factor leading to the occurrence and development of depression, and that overactivation of inflammatory factors such as NLRP3, Toll-like receptor 4, and IDO leads to immune-system dysfunction and depression. The other pathogenic hypothesis, the gut flora hypothesis, has also been the focus of recent research. The gut flora may work together with inflammatory factors to cause depression. The approach to treating depression has been by altering the gut flora through drugs or probiotics. However, effective and clear treatment methods are lacking. In this study, by exploring the involvement of intestinal flora and inflammatory factors in the pathogenesis of depression, we found that improving the intestinal flora can affect inflammatory factors and, therefore, provide research ideas for the development of novel drugs to treat depression.

Integrating Metabolomics and Network Pharmacology to Explore the Mechanism of Xiao-Yao-San in the Treatment of Inflammatory Response in CUMS Mice

Depression can trigger an inflammatory response that affects the immune system, leading to the development of other diseases related to inflammation. Xiao-Yao-San (XYS) is a commonly used formula in clinical practice for treating depression. However, it remains unclear whether XYS has a modulating effect on the inflammatory response associated with depression. The objective of this study was to examine the role and mechanism of XYS in regulating the anti-inflammatory response in depression. A chronic unpredictable mild stress (CUMS) mouse model was established to evaluate the antidepressant inflammatory effects of XYS. Metabolomic assays and network pharmacology were utilized to analyze the pathways and targets associated with XYS in its antidepressant inflammatory effects. In addition, molecular docking, immunohistochemistry, Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR), and Western Blot were performed to verify the expression of relevant core targets. The results showed that XYS significantly improved depressive behavior and attenuated the inflammatory response in CUMS mice. Metabolomic analysis revealed the reversible modulation of 21 differential metabolites by XYS in treating depression-related inflammation. Through the combination of liquid chromatography and network pharmacology, we identified seven active ingredients and seven key genes. Furthermore, integrating the predictions from network pharmacology and the findings from metabolomic analysis, Vascular Endothelial Growth Factor A (VEGFA) and Peroxisome Proliferator-Activated Receptor-γ (PPARG) were identified as the core targets. Molecular docking and related molecular experiments confirmed these results. The present study employed metabolomics and network pharmacology analyses to provide evidence that XYS has the ability to alleviate the inflammatory response in depression through the modulation of multiple metabolic pathways and targets.

Metabolic reprograming and increased inflammation by cadmium exposure following early-life respiratory syncytial virus infection-the involvement of protein S-palmitoylation

Early-life respiratory syncytial virus (RSV) infection (eRSV) is one of the leading causes of serious pulmonary disease in children. eRSV is associated with higher risk of developing asthma and compromised lung function later in life. Cadmium (Cd) is a toxic metal, widely present in the environment and in food. We recently showed that eRSV re-programs metabolism and potentiates Cd toxicity in the lung, and our transcriptome-metabolome-wide study showed strong associations between S-palmitoyl transferase expression and Cd-stimulated lung inflammation and fibrosis signaling. Limited information is available on the mechanism by which eRSV re-programs metabolism and potentiates Cd toxicity in the lung. In the current study, we used a mouse model to examine the role of protein S-palmitoylation (Pr-S-Pal) in low dose Cd-elevated lung metabolic disruption and inflammation following eRSV. Mice exposed to eRSV were later treated with Cd (3.3 mg CdCl2/L) in drinking water for 6 weeks (RSV+Cd). The role of Pr-S-Pal was studied using a palmitoyl transferase inhibitor, 2-bromopalmitate (BP, 10 µM). Inflammatory marker analysis showed that cytokines, chemokines and inflammatory cells were highest in the RSV+Cd group, and BP decreased inflammatory markers. Lung metabolomics analysis showed that pathways including phenylalanine, tyrosine and tryptophan, phosphatidylinositol and sphingolipid were altered across treatments. BP antagonized metabolic disruption of sphingolipid and glycosaminoglycan metabolism by RSV+Cd, consistent with BP effect on inflammatory markers. This study shows that Cd exposure following eRSV has a significant impact on subsequent inflammatory response and lung metabolism, which is mediated by Pr-S-Pal, and warrants future research for a therapeutic target.

Development of microRNA-based therapeutics for central nervous system diseases

MicroRNA (miRNA)-mediated gene silencing is a method of RNA interference in which a miRNA binds to messenger RNA sequences and regulates target gene expression. MiRNA-based therapeutics have shown promise in treating a variety of central nervous system diseases, as verified by results from diverse preclinical model organisms. Over the last decade, several miRNA-based therapeutics have entered clinical trials for various kinds of diseases, such as tumors, infections, and inherited diseases. However, such clinical trials for central nervous system diseases are scarce, and many central nervous system diseases, including hemorrhagic stroke, ischemic stroke, traumatic brain injury, intractable epilepsy, and Alzheimer's disease, lack effective treatment. Considering its effectiveness for central nervous system diseases in preclinical experiments, microRNA-based intervention may serve as a promising treatment for these kinds of diseases. This paper reviews basic principles and recent progress of miRNA-based therapeutics and summarizes general procedures to develop such therapeutics for treating central nervous system diseases. Then, the current obstacles in drug development are discussed. This review also provides a new perspective on possible solutions to these obstacles in the future.

Interleukin-6 and tumor necrosis factor-α attenuate dopamine release in mice fed a high-fat diet, but not medium or low-fat diets

Chronic low-grade inflammation is associated with a state of diet-induced obesity that impacts systemic tissues and can cross the blood-brain barrier to act directly on the brain. The extent to which pro-inflammatory cytokines released in these conditions affect dopamine presynaptic neurotransmission has not been previously investigated. The purpose of this study was to examine how dopamine terminals are affected by pro-inflammatory cytokines, and to determine if dietary fat consumption potentiates cytokine effects on dopamine release and reuptake rate in the nucleus accumbens (NAc). Male and female C57BL/6J mice were fed high, medium, or low-fat diets (60%, 30%, or 10% total kcals from fat, respectively) for six weeks. Fast scan cyclic voltammetry (FSCV) was used to measure dopamine release and reuptake rate in the NAc core from ex vivo coronal brain slices. Electrically evoked dopamine release and the maximal rate of dopamine reuptake (Vmax) were significantly lower in mice fed the 30% and 60% high-fat diets compared to the 10% low-fat group (p < 0.05). IL-6 5 or 10 nM or TNFα 30 or 300 nM was added to artificial cerebrospinal fluid (aCSF) bathed over brain slices during FSCV. No effect on dopamine release or Vmax was observed with lower concentrations. However, 10 nM IL-6 and 300 nM TNFα significantly reduced dopamine release in the 60% fat group (p < 0.05). No effect of added cytokine was observed on Vmax. Overall, these data provide evidence that dietary fat increases neural responsiveness to cytokines, which may help inform comorbidities between diet-induced obesity and depression or other mood disorders.

Stress circuitry: mechanisms behind nervous and immune system communication that influence behavior

Inflammatory processes are increased by stress and contribute to the pathology of mood disorders. Stress is thought to primarily induce inflammation through peripheral and central noradrenergic neurotransmission. In healthy individuals, these pro-inflammatory effects are countered by glucocorticoid signaling, which is also activated by stress. In chronically stressed individuals, the anti-inflammatory effects of glucocorticoids are impaired, allowing pro-inflammatory effects to go unchecked. Mechanisms underlying this glucocorticoid resistance are well understood, but the precise circuits and molecular mechanisms by which stress increases inflammation are not as well known. In this narrative review, we summarize the mechanisms by which chronic stress increases inflammation and contributes to the onset and development of stress-related mood disorders. We focus on the neural substrates and molecular mechanisms, especially those regulated by noradrenergic signaling, that increase inflammatory processes in stressed individuals. We also discuss key knowledge gaps in our understanding of the communication between nervous and immune systems during stress and considerations for future therapeutic strategies. Here we highlight the mechanisms by which noradrenergic signaling contributes to inflammatory processes during stress and how this inflammation can contribute to the pathology of stress-related mood disorders. Understanding the mechanisms underlying crosstalk between the nervous and immune systems may lead to novel therapeutic strategies for mood disorders and/or provide important considerations for treating immune-related diseases in individuals suffering from stress-related disorders.

Fatigue in Inflammatory Joint Diseases

Fatigue is a prevalent symptom in various rheumatic diseases, such as rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. It is characterised as a subjective, enduring feeling of generalised tiredness or exhaustion, impacting the patient's life quality and exacerbating disability. The fatigue nature is multifaceted, encompassing physiological, psychological, and social factors, and although the exact cause of inflammatory joint diseases is not fully understood, several factors are believed to contribute to its development. Despite high prevalence and importance, the symptom is often underestimated in clinical practice. Chronic inflammation, commonly associated with rheumatic diseases, has been proposed as a potential contributor to fatigue development. While current treatments effectively target inflammation and reduce disease activity, fatigue remains a persistent problem. Clinical evaluation of rheumatic diseases primarily relies on objective criteria, whereas fatigue, being a subjective symptom, is solely experienced and reported by the patient. Managing fatigue in inflammatory joint diseases involves a multifaceted approach. Identifying and comprehensively assessing the subjective components of fatigue in individual patients is crucial for effectively managing this symptom in everyday clinical practice.

Inflammation in the pathogenesis of depression: a disorder of neuroimmune origin

There are several hypotheses concerning the underlying pathophysiological mechanisms of major depression, which centre largely around adaptive changes in neuronal transmission and plasticity, neurogenesis, and circuit and regional connectivity. The immune and endocrine systems are commonly implicated in driving these changes. An intricate interaction of stress hormones, innate immune cells and the actions of soluble mediators of immunity within the nervous system is described as being associated with the symptoms of depression. Bridging endocrine and immune processes to neurotransmission and signalling within key cortical and limbic brain circuits are critical to understanding depression as a disorder of neuroimmune origins. Emergent areas of research include a growing recognition of the adaptive immune system, advances in neuroimaging techniques and mechanistic insights gained from transgenic animals. Elucidation of glial-neuronal interactions is providing additional avenues into promising areas of research, the development of clinically relevant disease models and the discovery of novel therapies. This narrative review focuses on molecular and cellular mechanisms that are influenced by inflammation and stress. The aim of this review is to provide an overview of our current understanding of depression as a disorder of neuroimmune origin, focusing on neuroendocrine and neuroimmune dysregulation in depression pathophysiology. Advances in current understanding lie in pursuit of relevant biomarkers, as the potential of biomarker signatures to improve clinical outcomes is yet to be fully realised. Further investigations to expand biomarker panels including integration with neuroimaging, utilising individual symptoms to stratify patients into more homogenous subpopulations and targeting the immune system for new treatment approaches will help to address current unmet clinical need.

Inflammation-induced reorientation of reward versus punishment sensitivity is attenuated by minocycline

BACKGROUND

Inflammation rapidly reorients motivational state, mood is impaired, pleasurable activities avoided and sensitivity to negative stimuli enhanced. When sustained, this can precipitate major depressive episodes. In humans, this has been linked to opposing actions of inflammation on striatal/insula reward/punishment learning signals while in rodents, motivational impairments can be attenuated with minocycline, implicating a mechanistic role for microglia. Here we investigated whether minocycline also inhibits the reorienting effects of lipopolysaccharide (LPS) on reward/punishment sensitivity in humans. Methods Using a crossover design, fifteen healthy volunteers underwent two experimental sessions in which they each received LPS (1 ng/kg) and placebo. Half (N = 8) received minocycline (100 mg bd) and half (N = 7) an identical looking placebo for 3½ days before each session. Six hours post-injection participants completed a probabilistic instrumental learning task in which they had to learn to select high probability reward (win £1) and avoid high probability punishment (lose £1) stimuli to maximise their gains and minimize losses. Physiological and sickness responses were sampled hourly and blood sampled at baseline, 3 and 6 h post-injection. Results LPS induced robust peripheral physiological: temperature, heart rate and immune: differential white cell, IL-6, TNF-α, IL-8, IL-10 responses (all condition × time interactions: p < 0.005), none were significantly modulated by minocycline (p > 0.1). LPS also biased behavior, enhancing punishment compared with reward sensitivity (F(1,13) = 6.10, p = 0.028). Minocycline significantly attenuated this inflammation-induced shift in reward versus punishment sensitivity (F(1,13) = 4.28, p = 0.033). Conclusions These data replicate the previous finding that systemic inflammation rapidly impairs sensitivity to rewards versus punishments in humans and extend this by implicating activated microglia in this acute motivational reorientation with implications for the development of microglial-targeted immune-modulatory therapies in depression.

Fight the Fire: Association of Cytokine Genomic Markers and Suicidal Behavior May Pave the Way for Future Therapies

The fight against suicide is highly challenging as it may be one of the most complex and, at the same time, most threatening among all psychiatric phenomena. In spite of its huge impact, and despite advances in neurobiology research, understanding and predicting suicide remains a major challenge for both researchers and clinicians. To be able to identify those patients who are likely to engage in suicidal behaviors and identify suicide risk in a reliable and timely manner, we need more specific, novel biological and genetic markers/indicators to develop better screening and diagnostic methods, and in the next step to utilize these molecules as intervention targets. One such potential novel approach is offered by our increasing understanding of the involvement of neuroinflammation based on multiple observations of increased proinflammatory states underlying various psychiatric disorders, including suicidal behavior. The present paper overviews our existing understanding of the association between suicide and inflammation, including peripheral and central biomarkers, genetic and genomic markers, and our current knowledge of intervention in suicide risk using treatments influencing inflammation; also overviewing the next steps to be taken and obstacles to be overcome before we can utilize cytokines in the treatment of suicidal behavior.

Dopamine Transmission Imbalance in Neuroinflammation: Perspectives on Long-Term COVID-19

Dopamine (DA) is a key neurotransmitter in the basal ganglia, implicated in the control of movement and motivation. Alteration of DA levels is central in Parkinson’s disease (PD), a common neurodegenerative disorder characterized by motor and non-motor manifestations and deposition of alpha-synuclein (α-syn) aggregates. Previous studies have hypothesized a link between PD and viral infections. Indeed, different cases of parkinsonism have been reported following COVID-19. However, whether SARS-CoV-2 may trigger a neurodegenerative process is still a matter of debate. Interestingly, evidence of brain inflammation has been described in postmortem samples of patients infected by SARS-CoV-2, which suggests immune-mediated mechanisms triggering the neurological sequelae. In this review, we discuss the role of proinflammatory molecules such as cytokines, chemokines, and oxygen reactive species in modulating DA homeostasis. Moreover, we review the existing literature on the possible mechanistic interplay between SARS-CoV-2-mediated neuroinflammation and nigrostriatal DAergic impairment, and the cross-talk with aberrant α-syn metabolism.

Investigation on property differences of ginseng and American ginseng by spatial metabolomics of neurochemicals with desorption electrospray ionization mass spectrometry imaging

ETHNOPHARMACOLOGICAL RELEVANCE

The properties are the body's response to traditional Chinese medicine (TCM). The essence of traditional Chinese medicine properties are cold, hot, warm, and cool. In the theory of traditional Chinese medicine, ginseng is warm and American ginseng is cool, they present two opposite properties. The material basis of property differences and effect mechanism of property degree need further investigation.

AIM OF THE STUDY

The aim of this work was to screen out the neurochemicals related to warm and cool properties of ginseng and American ginseng, and investigate the distributions of identified neurochemicals in rat brain and the metabolic mechanism.

MATERIALS AND METHODS

Spatial metabolomics was applied to study the effects of ginseng and American ginseng on the distributions of neurochemicals in rat brain by desorption electrospray ionization mass spectrometry imaging (DESI-MSI). Based on discriminant coefficients in partial least square discriminant analysis (PLS-DA) processing, neurochemicals related to warm and cool properties were classified. In addition, the score contributions of the neurochemicals markers could be used to evaluate the warm and cool property degrees.

RESULTS

A total of 25 neurochemicals were imaged and identified in brain section. The distribution regions of main neurochemicals were consistent with in sagittal and coronal sections of brain reported in literature. 17 neurochemicals were classified as warm markers. Meanwhile, 8 neurochemicals were identified as cool markers, correlated with the cool properties of American ginseng. It demonstrated that the score contributions of the 25 neurochemicals markers could be used to evaluate the warm and cool property degrees. Based on the regulatory effects of neurochemicals, the warm markers could promote the body's energy metabolism, improve the function of endocrine system, and enhance the excitability of central nervous system. The cool property markers have reduced excitability of central nervous system, weakened metabolism and stress response ability, thus presented the biological activity of cool and cold.

CONCLUSIONS

Our findings provided a rapid and effective visualization method for the spatial distribution and metabolism of small molecular neurochemicals in rat brain. DESI-MSI was a reference methodology for evaluating the properties of TCM.

Neural fatigue by passive induction: repeated stimulus exposure results in cognitive fatigue and altered representations in task-relevant networks

Cognitive fatigue is defined by a reduced capacity to perform mental tasks. Despite its pervasiveness, the underlying neural mechanisms remain elusive. Specifically, it is unclear whether prolonged effort affects performance through alterations in over-worked task-relevant neuronal assemblies. Our paradigm based on repeated passive visual stimulation discerns fatigue effects from the influence of motivation, skill and boredom. We induced performance loss and observed parallel alterations in the neural blueprint of the task, by mirroring behavioral performance with multivariate neuroimaging techniques (MVPA) that afford a subject-specific approach. Crucially, functional areas that responded the most to repeated stimulation were also the most affected. Finally, univariate analysis revealed clusters displaying significant disruption within the extrastriate visual cortex. In sum, here we show that repeated stimulation impacts the implicated brain areas' activity and causes tangible behavioral repercussions, providing evidence that cognitive fatigue can result from local, functional, disruptions in the neural signal induced by protracted recruitment.

Brain mapping inflammatory-arthritis-related fatigue in the pursuit of novel therapeutics

Despite developments in pharmacological treatments, chronic fatigue is an unresolved issue for most people with inflammatory arthritis that severely disrupts their personal and working lives. Fatigue in these patients is not strongly linked with peripheral disease activity but is associated with CNS-derived symptoms such as chronic pain, sleep disturbance, and depression. Therefore, a neurobiological basis should be considered when pursuing novel fatigue-specific therapeutics. In this Review, we focus on clinical imaging biomarkers that map candidate brain regions and are crucial in fatigue pathophysiology. We then evaluate neuromodulation techniques that could affect these candidate brain regions and are potential treatment strategies for fatigue in patients with inflammatory arthritis. We delineate work that is still required for neuroimaging and neuromodulation to eventually become part of a clinical pathway to treat and manage fatigue.

Metabolomics combined with serum pharmacochemistry discovering the potential effective compounds of Fangji Huangqi Tang against nephrotic syndrome

Fangji Huangqi Tang (FHT) was first recorded in "Jin Gui Yao Lue," invented by the archaic Chinese medical doctor Zhongjing Zhang, and is a classic medicine that tonifies qi and expels wind, invigorates spleen for diuresis. A large number of literatures indicated that FHT showed a significant effect on Nephrotic Syndrome (NS). A comprehensive strategy was proposed to discover the potential effective compounds and therapeutic targets of FHT against NS as a case study. Serum metabolomics combined with multivariate statistical analysis was employed to analysis and screen the differential endogenous metabolites in serum samples of the control and model rats induced by Adriamycin. The correlation analysis between the efficacy biomarkers and different compounds absorbed in serum of FHT was conducted to explore the potential effective compounds of FHT against NS. With the help of network pharmacology, the therapeutic targets and the possible molecular mechanisms of FHT against NS were further investigated. Fifteen metabolites, including l-phenylalanine, 3-Hydroxybutyric acid and linolenic acid, were associated with renal damage based on the serum metabolomic results. Metabolic pathway analysis indicated that phenylalanine, tyrosine and tryptophan biosynthesis and linoleic acid metabolism were the key pathways associated with NS. Among them, 6 metabolites were defined as efficacy biomarkers such as uric acid, 2-methylbutyrylcarnitine and 10-HDA. The results of correlation analysis suggested that 14 constituents such as fanGhinoline, cycloastragenol, atractylenolide III, and glycyrrhetinic acid were recognized as potential effective compounds, whose potential protein targets participated in the MAPK signaling pathway, GnRH signaling pathway and aldoaterone-regulated sodium reabsorption. This study has clarified the potential effective compounds and therapeutic targets of FHT against NS. The results provided new evidence for the pharmacological mechanism of FHT on NS.

Increased Inflammation and Treatment of Depression: From Resistance to Reuse, Repurposing, and Redesign

Based on mounting clinical and translational evidence demonstrating the impact of exogenously administered inflammatory stimuli on the brain and behavior, increased endogenous inflammation has received attention as one pathophysiologic process contributing to psychiatric illnesses and particularly depression. Increased endogenous inflammation is observed in a significant proportion of depressed patients and has been associated with reduced responsiveness to standard antidepressant therapies. This chapter presents recent evidence that inflammation affects neurotransmitters and neurocircuits to contribute to specific depressive symptoms including anhedonia, motor slowing, and anxiety, which may preferentially improve after anti-cytokine therapies in patients with evidence of increased inflammation. Existing and novel pharmacological strategies that target inflammation or its downstream effects on the brain and behavior will be discussed in the context of a need for intelligent trial design in order to meaningfully translate these concepts and develop more precise therapies for depressed patients with increased inflammation.

The Role of Inflammation and Oxidative Stress in Rheumatic Heart Disease

Rheumatic heart disease (RHD), an acquired valvular disease, remains an important cause of morbidity and mortality in developing countries. This chronic illness starts from untreated streptococcal throat infection, resulting in acute rheumatic fever (ARF) in susceptible individuals. Repeated infections lead to a chronic phase characterized by the damage of heart valves. Inflammation has been found to play important role in the development of this disease. All the studies presented in this review clearly show the involvement of the inflammatory state in the progression of this disease. However, the exact role of cytokines in inflammation sites remains to be examined, since most studies have so far focused on peripheral blood. Such analysis would provide information on inflammatory mechanisms in situ.

Activation of dopamine D2 receptors attenuates neuroinflammation and ameliorates the memory impairment induced by rapid eye movement sleep deprivation in a murine model

The proinflammatory state, which may be induced by sleep deprivation, seems to be a determining factor in the development of neurodegenerative processes. Investigations of mechanisms that help to mitigate the inflammatory effects of sleep disorders are important. A new proposal involves the neurotransmitter dopamine, which may modulate the progression of the immune response by activating receptors expressed on immune cells. This study aimed to determine whether dopamine D2 receptor (D2DR) activation attenuates the proinflammatory response derived from rapid eye movement (REM) sleep deprivation in mice. REM sleep deprivation (RSD) was induced in 2-month-old male CD1 mice using the multiple platform model for three consecutive days; during this period, the D2DR receptor agonist quinpirole (QUIN) was administered (2 mg/kg/day i.p.). Proinflammatory cytokine levels were assessed in serum and homogenates of the brain cortex, hippocampus, and striatum using ELISAs. Long-term memory deficits were identified using the Morris water maze (MWM) and novel object recognition (NOR) tests. Animals were trained until learning criteria were achieved; then, they were subjected to RSD and treated with QUIN for 3 days. Memory evocation was determined afterward. Moreover, we found RSD induced anhedonia, as measured by the sucrose consumption test, which is commonly related to the dopaminergic system. Our data revealed increased levels of proinflammatory cytokines (TNFα and IL-1β) in both the hippocampus and serum from RSD mice. However, QUIN attenuated the increased levels of these cytokines. Furthermore, RSD caused a long-term memory evocation deficit in both the MWM and NOR tests. In contrast, QUIN coadministration during the RSD period significantly improved the performance of the animals. On the other hand, QUIN prevented the anhedonic condition induced by RSD. Based on our results, D2DR receptor activation protects against memory impairment induced by disturbed REM sleep by inhibiting neuroinflammation.

Functional connectivity in reward circuitry and symptoms of anhedonia as therapeutic targets in depression with high inflammation: evidence from a dopamine challenge study

Increased inflammation in major depressive disorder (MDD) has been associated with low functional connectivity (FC) in corticostriatal reward circuits and symptoms of anhedonia, relationships which may involve the impact of inflammation on synthesis and release of dopamine. To test this hypothesis while establishing a platform to examine target engagement of potential therapies in patients with increased inflammation, medically stable unmedicated adult MDD outpatients enrolled to have a range of inflammation (as indexed by plasma C-reactive protein [CRP] levels) were studied at two visits involving acute challenge with the dopamine precursor levodopa (L-DOPA; 250 mg) and placebo (double-blind, randomized order ~1-week apart). The primary outcome of resting-state (rs)FC in a classic ventral striatum to ventromedial prefrontal cortex reward circuit was calculated using a targeted, a priori approach. Data available both pre- and post-challenge (n = 31/40) established stability of rsFC across visits and determined CRP > 2 mg/L as a cut-point for patients exhibiting positive FC responses (post minus pre) to L-DOPA versus placebo (p < 0.01). Higher post-L-DOPA FC in patients with CRP > 2 mg/L was confirmed in all patients (n = 40) where rsFC data were available post-challenge (B = 0.15, p = 0.006), and in those with task-based (tb)FC during reward anticipation (B = 0.15, p = 0.013). While effort-based motivation outside the scanner positively correlated with rsFC independent of treatment or CRP, change in anhedonia scores negatively correlated with rsFC after L-DOPA only in patients with CRP > 2 mg/L (r = -0.56, p = 0.012). FC in reward circuitry should be further validated in larger samples as a biomarker of target engagement for potential treatments including dopaminergic agents in MDD patients with increased inflammation.

The role of the immune system in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) develops in a subset of individuals upon exposure to traumatic stress. In addition to well-defined psychological and behavioral symptoms, some individuals with PTSD also exhibit elevated concentrations of inflammatory markers, including C-reactive protein, interleukin-6, and tumor necrosis factor-α. Moreover, PTSD is often co-morbid with immune-related conditions, such as cardiometabolic and autoimmune disorders. Numerous factors, including lifetime trauma burden, biological sex, genetic background, metabolic conditions, and gut microbiota, may contribute to inflammation in PTSD. Importantly, inflammation can influence neural circuits and neurotransmitter signaling in regions of the brain relevant to fear, anxiety, and emotion regulation. Given the link between PTSD and the immune system, current studies are underway to evaluate the efficacy of anti-inflammatory treatments in those with PTSD. Understanding the complex interactions between PTSD and the immune system is essential for future discovery of diagnostic and therapeutic tools.

Cellular and immunometabolic mechanisms of inflammation in depression: Preliminary findings from single cell RNA sequencing and a tribute to Bruce McEwen

Inflammation is associated with symptoms of anhedonia, a core feature of major depression (MD). We have shown that MD patients with high inflammation as measured by plasma C-reactive protein (CRP) and anhedonia display gene signatures of metabolic reprograming (e.g., shift to glycolysis) necessary to sustain cellular immune activation. To gain preliminary insight into the immune cell subsets and transcriptomic signatures that underlie increased inflammation and its relationship with behavior in MD at the single-cell (sc) level, herein we conducted scRNA-Seq on peripheral blood mononuclear cells from a subset of medically-stable, unmedicated MD outpatients. Three MD patients with high CRP (>3 mg/L) before and two weeks after anti-inflammatory challenge with the tumor necrosis factor antagonist infliximab and three patients with low CRP (≤3 mg/L) were studied. Cell clusters were identified using a Single Cell Wizard pipeline, followed by pathway analysis. CD14⁺ and CD16⁺ monocytes were more abundant in MD patients with high CRP and were reduced by 29% and 55% respectively after infliximab treatment. Within CD14⁺ and CD16⁺ monocytes, genes upregulated in high CRP patients were enriched for inflammatory (phagocytosis, complement, leukocyte migration) and immunometabolic (hypoxia-inducible factor [HIF]-1, aerobic glycolysis) pathways. Shifts in CD4⁺ T cell subsets included ∼30% and ∼10% lower abundance of CD4⁺ central memory (T_CM) and naïve cells and ∼50% increase in effector memory-like (T_EM-like) cells in high versus low CRP patients. T_CM cells of high CRP patients displayed downregulation of the oxidative phosphorylation (OXPHOS) pathway, a main energy source in this cell type. Following infliximab, changes in the number of CD14⁺ monocytes and CD4⁺ T_EM-like cells predicted improvements in anhedonia scores (r = 1.0, p < 0.001). In sum, monocytes and CD4⁺ T cells from MD patients with increased inflammation exhibited immunometabolic reprograming in association with symptoms of anhedonia. These findings are the first step toward determining the cellular and molecular immune pathways associated with inflammatory phenotypes in MD, which may lead to novel immunomodulatory treatments of psychiatric illnesses with increased inflammation.

Serum metabolomics study of anxiety disorder patients based on LC-MS

BACKGROUND

In the current environment of increasing social pressure, anxiety disorder has become a kind of health problem that needs to be solved urgently. However, the pathological mechanism of anxiety is still unclear, the classification of clinical diagnosis and symptoms is complex, and there is still a lack of biomarkers that can be identified and judged.

METHODS

This study used LC-MS and non-targeted metabolomics to analyze the clinically collected plasma of 18 samples from anxiety disorder patients and 31 samples from healthy people to screen differential metabolites and perform subsequent metabolic pathway analysis. Binary Logistic regression was used to construct the anxiety disorder diagnosis prediction model and evaluate the prediction efficacy.

RESULTS

The results showed that 22 metabolites were disturbed in the plasma of anxiety patients compared with healthy people. These metabolites mainly participate in 6 metabolic pathways. The combined diagnostic factors 4-Acetamidobutanoate, 3-Hydroxysebacic acid, and Cytosine were used to construct the diagnosis prediction model. The prediction probability of the model is 91.8%, the Youden index is 0.889, the sensitivity is 0.889, and the specificity is 1.000, so the prediction effect is good.

CONCLUSIONS

This study preliminarily analyzed and explored the differences between plasma samples from patients with anxiety disorder and healthy individuals, increased the types of potential biomarkers for anxiety disorder, and provided a valuable reference for subsequent research related to anxiety disorder.

Neopterin Relates to Lifetime Depression in Older Adults With HIV on Suppressive Antiretroviral Therapy

BACKGROUND

Chronic inflammation contributes to the pathogenesis of depression in persons with HIV (PWH). Neopterin, a biomarker of HIV-related immune activation that partially normalizes with antiretroviral therapy (ART), correlates with major depressive disorder (MDD) and subclinical depressive symptoms in persons without HIV and acutely infected, young PWH. The sensitivity of neopterin, however, to both lifetime and current depression is poorly understood in older PWH on suppressive ART.

METHODS

Participants were 70 PWH and 35 persons without HIV (HIV-) who were at least 50 years old and completed standardized neurobehavioral and neuromedical assessments. Depressive symptoms in the past 2 weeks, measured with the Beck Depression Inventory-II (BDI-II), and lifetime MDD diagnoses, defined as meeting Diagnostic and Statistical Manual of Mental Disorders-IV criteria for a depressive episode at any point in one's lifetime, were separately modeled as a function of plasma neopterin levels in the full sample and by HIV serostatus.

RESULTS

Compared with HIV- adults, PWH had higher neopterin levels (P < 0.001) and BDI-II scores (P < 0.01) and were more likely to have lifetime MDD (P < 0.01). Higher neopterin related to lifetime MDD, but only in PWH, even after controlling for clinically relevant comorbidities and treatment factors in logistic regression (odds ratio = 3.11, P = 0.002). Higher neopterin correlated with higher BDI-II scores in the full sample (rs = 0.25; P = 0.010), but not within either group (PWH: rs = 0.03, P = 0.819; HIV-: rs = 0.09, P = 0.588).

CONCLUSION

Neopterin was associated with lifetime MDD, but not current depressive symptoms in older PWH on suppressive ART. This may reflect a legacy of inflammation-related disruptions to amino acid metabolism and neurotransmitter synthesis, similar to prior observations. Identification of biopsychosocial and resilience factors underlying the null association between neopterin and current depression in older PWH is warranted.

Co-occurrence of Fatigue and Depression in People With Multiple Sclerosis: A Mini-Review

Fatigue and depression are common conditions diagnosed in people with multiple sclerosis (MS). Fatigue defined as subjective lack of physical and/or mental energy is present in 35–97% of people with MS, who classify it as one of the most serious symptoms interfering with daily activities and influencing the quality of life. Depression is diagnosed in about 50% of people with MS. Since fatigue and depression frequently coexists, it may be quite hard to differentiate them. Primary fatigue and primary depression in MS are caused by inflammatory, oxidative/nitrosative, and neurodegenerative processes leading to demyelination, axonal damage, and brain atrophy. In people with MS and comorbid fatigue and/or depression there is reported increased serum and cerebrospinal fluid concentration of inflammatory mediators such as tumor necrosis factor, interleukins (IL-1a, IL-1b, IL-6), interferon γ and neopterin. Moreover, the brain atrophy of prefrontal, frontal, parietotemporal regions, thalamus, and basal ganglia was observed in people with MS with fatigue and/or depression. The secondary fatigue and secondary depression in people with MS may be caused by emotional factors, sleep disorders, pain, the coexistence of other diseases, and the use of medications. In some studies, the use of disease-modifying therapies positively influenced fatigue, probably by reducing the inflammatory response, which proves that fatigue and depression are closely related to immunological factors. In this mini-review, the pathogenesis, methods of evaluation and differentiation, and possible therapies for fatigue and depression in MS are discussed.

Cytokine profile in drug-naïve panic disorder patients

Although accumulating evidence suggests that inflammatory processes play a role in the pathophysiology of mental disorders, few studies have investigated this matter in panic disorder (PD). Furthermore, no studies to date have evaluated cytokine levels in drug-naïve patients with PD. Therefore, little is known about the presence of inflammation at the onset of this disorder. The aim of the present study was to determine the levels of the proinflammatory interleukins IL-1B and IL-2R and the anti-inflammatory cytokine IL-10 in drug-naïve PD patients. Analysis of serum chemokine levels revealed increased proinflammatory activity in the early phase of PD through increased IL-2R and IL-1B levels and a decrease in IL-10 levels in drug-naïve PD patients compared to matched healthy controls. Neurotransmitters and neurocircuits that are targets of inflammatory responses are discussed, followed by an examination of brain-immune interactions as risk factors for PD. This study is the first to identify a proinflammatory cytokine response in drug-naïve PD subjects. These findings indicate that treatments targeting proinflammatory markers may ameliorate anxiety symptoms in PD patients.

Inflammation as a Pathophysiologic Pathway to Anhedonia: Mechanisms and Therapeutic Implications

Anhedonia, characterized by a lack of motivation, interest, or ability to experience pleasure, is a prominent symptom of depression and other psychiatric disorders and has been associated with poor response to standard therapies. One pathophysiologic pathway receiving increased attention for its potential role in anhedonia is inflammation and its effects on the brain. Exogenous administration of inflammatory stimuli to humans and laboratory animals has reliably been found to affect neurotransmitters and neurocircuits involved in reward processing, including the ventral striatum and ventromedial prefrontal cortex, in association with reduced motivation. Moreover, a rich literature including meta-analyses describes increased inflammation in a significant proportion of patients with depression and other psychiatric illnesses involving anhedonia, as evident by elevated inflammatory cytokines, acute phase proteins, chemokines, and adhesion molecules in both the periphery and central nervous system. This endogenous inflammation may arise from numerous sources including stress, obesity or metabolic dysfunction, genetics, and lifestyle factors, many of which are also risk factors for psychiatric illness. Consistent with laboratory studies involving exogenous administration of peripheral inflammatory stimuli, neuroimaging studies have further confirmed that increased endogenous inflammation in depression is associated with decreased activation of and reduced functional connectivity within reward circuits involving ventral striatum and ventromedial prefrontal cortex in association with anhedonia. Here, we review recent evidence of relationships between inflammation and anhedonia, while highlighting translational and mechanistic work describing the impact of inflammation on synthesis, release, and reuptake of neurotransmitters like dopamine and glutamate that affects circuits to drive motivational deficits. We will then present insight into novel pharmacological strategies that target either inflammation or its downstream effects on the brain and behavior. The meaningful translation of these concepts through appropriately designed trials targeting therapies for psychiatric patients with high inflammation and transdiagnostic symptoms of anhedonia is also discussed.

Polyphenols inhibiting MAPK signalling pathway mediated oxidative stress and inflammation in depression

Depression is one of the most debilitating psychiatric disorders affecting people of all ages worldwide. Despite significant heterogeneity between studies, increased inflammation and oxidative stress have been found in depression. Oxidative stress and inflammation are involved in the pathogenesis of depression. In the current review, we discussed the markers of oxidative stress and inflammation in depressive disorder and the association between these markers and the antidepressant treatment. The role of natural polyphenols in regulating various cell signaling pathways related to oxidative stress and inflammation has also been reviewed. The inhibitory effect of polyphenols on several cell signaling pathways reveals the vital role of polyphenols in the prevention and treatment of depressive disorder. Understanding the mechanism of polyphenols implicated in the regulation of cell signaling pathways is essential for the identification of lead compounds and the development of novel effective compounds for the prevention and treatment of depressive disorder.

Integrating the monoamine and cytokine hypotheses of depression: Is histamine the missing link?

Psychiatric diseases, like depression, largely affect the central nervous system (CNS). While the underlying neuropathology of depressive illness remains to be elucidated, several hypotheses have been proposed as molecular underpinnings for major depressive disorder, including the monoamine hypothesis and the cytokine hypothesis. The monoamine hypothesis has been largely supported by the pharmaceuticals that target monoamine neurotransmitters as a treatment for depression. However, these antidepressants have come under scrutiny due to their limited clinical efficacy, side effects, and delayed onset of action. The more recent, cytokine hypothesis of depression is supported by the ability of immune-active agents to induce "sickness behaviour" akin to that seen with depression. However, treatments that more selectively target inflammation have yielded inconsistent antidepressive results. As such, neither of these hypotheses can fully explain depressive illness pathology, implying that the underlying neuropathological mechanisms may encompass aspects of both theories. The goal of the current review is to integrate these two well-studied hypotheses and to propose a role for histamine as a potential unifying factor that links monoamines to cytokines. Additionally, we will focus on stress-induced depression, to provide an updated perspective of depressive illness research and thereby identify new potential targets for the treatment of major depressive disorder.

Aiding and Abetting Anhedonia: Impact of Inflammation on the Brain and Pharmacological Implications

Exogenous administration of inflammatory stimuli to humans and laboratory animals and chronic endogenous inflammatory states lead to motivational deficits and ultimately anhedonia, a core and disabling symptom of depression present in multiple other psychiatric disorders. Inflammation impacts neurotransmitter systems and neurocircuits in subcortical brain regions including the ventral striatum, which serves as an integration point for reward processing and motivational decision-making. Many mechanisms contribute to these effects of inflammation, including decreased synthesis, release and reuptake of dopamine, increased synaptic and extrasynaptic glutamate, and activation of kynurenine pathway metabolites including quinolinic acid. Neuroimaging data indicate that these inflammation-induced neurotransmitter effects manifest as decreased activation of ventral striatum and decreased functional connectivity in reward circuitry involving ventral striatum and ventromedial prefrontal cortex. Neurocircuitry changes in turn mediate nuanced effects on motivation that include decreased willingness to expend effort for reward while maintaining the ability to experience reward. Taken together, the data reveal an inflammation-induced pathophysiologic phenotype that is agnostic to diagnosis. Given the many mechanisms involved, this phenotype represents an opportunity for development of novel and/or repurposed pharmacological strategies that target inflammation and associated cellular and systemic immunometabolic changes and their downstream effects on the brain. To date, clinical trials have failed to capitalize on the unique nature of this transdiagnostic phenotype, leaving the field bereft of interpretable data for meaningful clinical application. However, novel trial designs incorporating established targets in the brain and/or periphery using relevant outcome variables (e.g., anhedonia) are the future of targeted therapy in psychiatry. SIGNIFICANCE STATEMENT: Emerging understanding of mechanisms by which peripheral inflammation can affect the brain and behavior has created unprecedented opportunities for development of pharmacological strategies to treat deficits in motivation including anhedonia, a core and disabling symptom of depression well represented in multiple psychiatric disorders. Mechanisms include inflammation and cellular and systemic immunometabolism and alterations in dopamine, glutamate, and kynurenine metabolites, revealing a target-rich environment that nevertheless has yet to be fully exploited by current clinical trial designs and drugs employed.

Immunoregulation and antidepressant effect of ketamine

Major depressive disorder (MDD) is a common mental health disorder that brings severe disease burden worldwide. Traditional antidepressants are mainly targeted at monoamine neurotransmitters, with low remission rates and high recurrence rates. Ketamine is a noncompetitive glutamate N-methyl-d-aspartate receptor (NMDAR) antagonist, and its rapid and powerful antidepressant effects have come to light. Its antidepressant mechanism is still unclarified. Research found that ketamine had not only antagonistic effect on NMDAR but also strong immunomodulatory effect, both of which were closely related to the pathophysiology of MDD. Although there are many related studies, they are relatively heterogeneous. Therefore, this review mainly describes the immune mechanisms involved in MDD and how ketamine plays an antidepressant role by regulating peripheral and central immune system, including peripheral inflammatory cytokines, central microglia, and astrocytes. This review summarizes the related research, finds out the deficiencies of current research, and provides ideas for future research and the development of novel antidepressants.

Embelin ameliorates cognitive dysfunction and progression of kindling in pentylenetetrazol-induced kindling in mice by attenuating brain inflammation

OBJECTIVE

This study was conducted to evaluate the effect of embelin (EMB) on various epileptic models and related brain inflammation.

METHODS

Male Swiss albino mice were administered EMB (5, 10, and 20 mg/kg/p.o.) in acute and chronic study for 7 days and 35 days, respectively. Acute study included increasing current electroshock (ICES) and pentylenetetrazol (PTZ)-induced seizure test. Step-down latency (SDL) and forced swim test (FST) were performed to evaluate cognitive functions and depression-like behavior, respectively. Chronic study included PTZ-induced kindling. Levels of inflammatory biomarkers, namely interleukin-1 beta (IL-1β), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), were estimated in the hippocampus and cortex of the kindled brains by ELISA technique. Further, neurotransmitters (NTs), namely gamma aminobutyric acid (GABA), glutamate, and dopamine, were estimated by using validated liquid chromatography-mass spectrometry (LC-MS) method followed by ultra-high-performance liquid chromatography (UHPLC).

RESULTS

Embelin (EMB) treatment increased the seizure threshold to hind limb extension (HLE) in the ICES test and decreased the seizure scores in the kindling experiment. Significantly low levels of IL-1β, IL-1Ra, IL-6, and TNF-α were observed in the hippocampus of PTZ + EMB (10 and 20 mg/kg)-treated groups compared with PTZ+ vehicle-treated group. Significantly lower levels of IL-1Ra, IL-6, and TNF-α compared with PTZ+ vehicle-treated group were observed in the cortex of PTZ + EMB (10 and 20 mg/kg)-treated groups, while IL-1β levels were found to be significantly lower only in the cortex of PTZ + EMB (20 mg/kg)-treated group. Increased levels of dopamine and GABA and decreased levels of glutamate in both hippocampus and cortex were observed in EMB + PTZ-treated groups compared with vehicle + PTZ-treated group. Latency of step down was found to be increased and immobility time in FST was decreased in EMB + PTZ groups compared with vehicle + PTZ group.

CONCLUSION

Embelin suppressed epileptogenesis in the kindled mice via neurochemical modulation of neurotransmitters and inhibiting the inflammatory pathway. Further, EMB was also observed to be protecting the kindled animals from cognition and depression-like behavior.

Blue Monday: Co-occurring Stimulant Use and HIV Persistence Predict Dysregulated Catecholamine Synthesis

BACKGROUND

This longitudinal study examined whether co-occurring stimulant use and HIV disease processes predicted greater risk for depression via dysregulated metabolism of amino acid precursors for neurotransmitters.

METHODS

In total, 110 sexual minority men (ie, gay, bisexual, and other men who have sex with men) living with HIV who had biologically confirmed recent methamphetamine use were enrolled in a randomized controlled trial. The kynurenine/tryptophan (K/T) and phenylalanine/tyrosine (P/T) ratios were measured over 15 months to index dysregulated metabolism of amino acid precursors for serotonin and catecholamines. Markers of gut-immune dysregulation such as lipopolysaccharide binding protein and soluble CD14 (sCD14), HIV persistence in immune cells (ie, proviral HIV DNA), and stimulant use were examined as predictors. These bio-behavioral measures, including the K/T and P/T ratios, were also examined as predictors of greater risk for depression over 15 months.

RESULTS

Higher time-varying sCD14 levels (β = 0.13; P = 0.04) and time-varying detectable viral loads (β = 0.71; P < 0.001) were independent predictors of a higher K/T ratio. Time-varying reactive urine toxicology results for stimulants (β = 0.53; P < 0.001) and greater proviral HIV DNA at baseline (β = 0.34; P < 0.001) independently predicted an increased P/T ratio. Greater time-varying, self-reported methamphetamine use uniquely predicted higher odds of screening positive for depression (Adjusted Odds Ratio = 1.08; 95% confidence interval: 1.01 to 1.17).

CONCLUSIONS

Ongoing stimulant use and HIV persistence independently predict dysregulated metabolism of amino acid precursors for catecholamines, but this did not explain amplified risk for depression.

What can neuroimmunology teach us about the symptoms of long-COVID?

Long-Coronavirus Disease (Long-COVID) is becoming increasingly recognized due to the persistence of symptoms such as profound fatigue, neurocognitive difficulties, muscle pains and weaknesses and depression, which would last beyond 3-12 weeks following infection with SARS-CoV-2. These particular symptoms have been extensively observed and studied in the context of previous psychoneuroimmunology research. In this short commentary, we discuss how previous neuroimmunology studies could help us to better understand pathways behind the development of these prolonged symptoms. Various mechanisms, including viral neuroinvasion, glial cells activation, neurogenesis, oxidative stress have been shown to explain these symptoms in the context of other disorders. Previous neuroimmunology findings could represent helpful pointers for future research on long-COVID symptoms and suggest potential management strategies for patients suffering with long-COVID.

Inflammatory Depression-Mechanisms and Non-Pharmacological Interventions

Treatment of depression is hampered by the failure to identify distinct symptom profiles with distinct pathophysiologies that differentially respond to distinct treatments. We posit that inflammatory depression is a meaningful depression subtype associated with specific symptoms and biological abnormalities. We review several upstream, potentially causative, mechanisms driving low-grade inflammation in this subtype of depression. We also discuss downstream mechanisms mediating the link between inflammation and symptoms of depression, including alterations in dopaminergic neurotransmission and tryptophan metabolism. Finally, we review evidence for several non-pharmacological interventions for inflammatory depression, including probiotics, omega-3 fatty acids, and physical exercise interventions. While some evidence suggests that these interventions may be efficacious in inflammatory depression, future clinical trials should consider enriching patient populations for inflammatory markers, or stratify patients by inflammatory status, to confirm or refute this hypothesis.

Appetite Regulation of TLR4-Induced Inflammatory Signaling

Appetite is the basis for obtaining food and maintaining normal metabolism. Toll-like receptor 4 (TLR4) is an important receptor expressed in the brain that induces inflammatory signaling after activation. Inflammation is considered to affect the homeostatic and non-homeostatic systems of appetite, which are dominated by hypothalamic and mesolimbic dopamine signaling. Although the pathological features of many types of inflammation are known, their physiological functions in appetite are largely unknown. This review mainly addresses several key issues, including the structures of the homeostatic and non-homeostatic systems. In addition, the mechanism by which TLR4-induced inflammatory signaling contributes to these two systems to regulate appetite is also discussed. This review will provide potential opportunities to develop new therapeutic interventions that control appetite under inflammatory conditions.

Plasma Metabolomics Profiling of Metabolic Pathways Affected by Major Depressive Disorder

Background: Major depressive disorder (MDD) is a common disease which is complicated by metabolic disorder. Although MDD has been studied relatively intensively, its metabolism is yet to be elucidated. Methods: To profile the global pathophysiological processes of MDD patients, we used metabolomics to identify differential metabolites and applied a new database Metabolite set enrichment analysis (MSEA) to discover dysfunctions of metabolic pathways of this disease. Hydrophilic metabolomics were applied to identify metabolites by profiling the plasma from 55 MDD patients and 100 sex-, gender-, BMI-matched healthy controls. The metabolites were then analyzed in MSEA in an attempt to discover different metabolic pathways. To investigate dysregulated pathways, we further divided MDD patients into two cohorts: (1) MDD patients with anxiety symptoms and (2) MDD patients without anxiety symptoms. Results: Metabolites which were hit in those pathways correlated with depressive and anxiety symptoms. Altogether, 17 metabolic pathways were enriched in MDD patients, and 23 metabolites were hit in those pathways. Three metabolic pathways were enriched in MDD patients without anxiety, including glycine and serine metabolism, arginine and proline metabolism, and phenylalanine and tyrosine metabolism. In addition, L-glutamic acid was positively correlated with the severity of depression and retardation if hit in MDD patients without anxiety symptoms. Conclusions: Different kinds of metabolic pathophysiological processes were found in MDD patients. Disorder of glycine and serine metabolism was observed in both MDD patients with anxiety and those without.

Tetrahydrobioterin (BH4) Pathway: From Metabolism to Neuropsychiatry

Tetrahydrobipterin (BH4) is a pivotal enzymatic cofactor required for the synthesis of serotonin, dopamine and nitric oxide. BH4 is essential for numerous physiological processes at periphery and central levels, such as vascularization, inflammation, glucose homeostasis, regulation of oxidative stress and neurotransmission. BH4 de novo synthesis involves the sequential activation of three enzymes, the major controlling point being GTP cyclohydrolase I (GCH1). Complementary salvage and recycling pathways ensure that BH4 levels are tightly kept within a physiological range in the body. Even if the way of transport of BH4 and its ability to enter the brain after peripheral administration is still controversial, data showed increased levels in the brain after BH4 treatment. Available evidence shows that GCH1 expression and BH4 synthesis are stimulated by immunological factors, notably pro-inflammatory cytokines. Once produced, BH4 can act as an anti- inflammatory molecule and scavenger of free radicals protecting against oxidative stress. At the same time, BH4 is prone to autoxidation, leading to the release of superoxide radicals contributing to inflammatory processes, and to the production of BH2, an inactive form of BH4, reducing its bioavailability. Alterations in BH4 levels have been documented in many pathological situations, including Alzheimer's disease, Parkinson's disease and depression, in which increased oxidative stress, inflammation and alterations in monoaminergic function are described. This review aims at providing an update of the knowledge about metabolism and the role of BH4 in brain function, from preclinical to clinical studies, addressing some therapeutic implications.

Skimmetin/osthole mitigates pain-depression dyad via inhibiting inflammatory and oxidative stress-mediated neurotransmitter dysregulation

Pain and depression are often co-existing pathological states that promote mutual severity resulting in limited efficacy of current treatment strategies. Thus, there is a need to develop an efficacious alternate treatment regimen for pain-depression dyad. Skimmetin and osthole are molecules of natural origin that have been explored for an anti-hyperglycemic, anti-bacterial, anti-fungal, and anti-diabetic activities in preclinical studies. in animal models. The current study has been designed to explore the beneficial effect of skimmetin/osthole in reserpine-induced pain-depression dyad in mice. Female Swiss albino mice (n = 6) were challenged with reserpine (0.5 mg/kg s.c.) for the first 3 days to induce a pain-depression dyad-like state. Skimmetin (10 mg/kg i.p.) and osthole (10 mg/kg i.p.) were administered for 5 days consecutively, starting from the first day of study. Reserpine treatment significantly reduced the pain threshold in the pressure application measurement (PAM) and electronic von frey (eVF) test. In forced swim test (FST) and Morris water maze (MWM) test mice displayed an increased immobility time and latency to reach platform respectively. Biochemical results showed an increased level of TNF-α, IL-1β, TBARS, glutamate, and reduced level of GSH, norepinephrine, and serotonin in the reserpine treated group. Reserpine treatment also increased brain MAO-A activity. Skimmetin/osthole treatment was found to attenuate the behavioral and biochemical alterations induced by reserpine. The results of the current investigation delineated that skimmetin/osthole may exert anti-nociceptive, anti-depressant, and improved cognition via inhibiting inflammatory and oxidative stress-mediated neurotransmitter dysregulation.

Intracerebroventricular Administration of Interferon-Alpha Induced Depressive-Like Behaviors and Neurotransmitter Changes in Rhesus Monkeys

Interferon-alpha (IFN-α) is a cytokine widely used in the treatment of brain cancers and virus infections with side effects including causing depression. Monoamine neurotransmitter systems have been found playing important roles in peripheral IFN-α-induced depression, but how peripheral IFN-α accesses the central nervous system and contributes to the development of depression is poorly known. This study aimed to develop a non-human primate model using long-term intracerebroventricular (i.c.v.) administration of IFN-α (5 days/week for 6 weeks), to observe the induced depressive-like behaviors and to explore the contributions of monoamine neurotransmitter systems in the development of depression. In monkeys receiving i.c.v. IFN-α administration, anhedonia was observed as decreases of sucrose consumption, along with depressive-like symptoms including increased huddling behavior, decreases of spontaneous and reactive locomotion in home cage, as well as reduced exploration and increased motionless in the open field. Chronic central IFN-α infusion significantly increased the cerebrospinal fluid (CSF) concentrations of noradrenaline (NA), and 3,4-dihydroxyphenylacetic acid (DOPAC), but not 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA). These CSF monoamine metabolites showed associations with some specific depression-related behaviors. In conclusion, central IFN-α administration induced anhedonia and depression-related behaviors comparable to the results with peripheral administration, and the development of depression was associated with the dysfunction of monoamine neurotransmitters.

Transcutaneous vagal nerve stimulation blocks stress-induced activation of Interleukin-6 and interferon-γ in posttraumatic stress disorder: A double-blind, randomized, sham-controlled trial

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory function. Vagus nerve stimulation (VNS) decreases inflammation, however few studies have examined the effects of non-invasive VNS on physiology in human subjects, and no studies in patients with PTSD. The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on inflammatory responses to stress. Thirty subjects with a history of exposure to traumatic stress with (N ​= ​10) and without (N ​= ​20) PTSD underwent exposure to stressful tasks immediately followed by active or sham tcVNS and measurement of multiple biomarkers of inflammation (interleukin-(IL)-6, IL-2, IL-1β, Tumor Necrosis Factor alpha (TNFα) and Interferon gamma (IFNγ) over multiple time points. Stressful tasks included exposure to personalized scripts of traumatic events on day 1, and public speech and mental arithmetic (Mental Stress) tasks on days 2 and 3. Traumatic scripts were associated with a pattern of subjective anger measured with Visual Analogue Scales and increased IL-6 and IFNγ in PTSD patients that was blocked by tcVNS (p ​< ​.05). Traumatic stress had minimal effects on these biomarkers in non-PTSD subjects and there was no difference between tcVNS or sham. No significant differences were seen between groups in IL-2, IL-1β, or TNFα. These results demonstrate that tcVNS blocks behavioral and inflammatory responses to stress reminders in PTSD.

Fatigue, depression, and pain in multiple sclerosis: How neuroinflammation translates into dysfunctional reward processing and anhedonic symptoms

Fatigue, depression, and pain affect the majority of multiple sclerosis (MS) patients, which causes a substantial burden to patients and society. The pathophysiology of these symptoms is not entirely clear, and current treatments are only partially effective. Clinically, these symptoms share signs of anhedonia, such as reduced motivation and a lack of positive affect. In the brain, they are associated with overlapping structural and functional alterations in areas involved in reward processing. Moreover, neuroinflammation has been shown to directly impede monoaminergic neurotransmission that plays a key role in reward processing. Here, we review recent neuroimaging and neuroimmunological findings, which indicate that dysfunctional reward processing might represent a shared functional mechanism fostering the symptom cluster of fatigue, depression, and pain in MS. We propose a framework that integrates these findings with a focus on monoaminergic neurotransmission and discuss its therapeutic implications, limitations, and perspectives.

Lower CSF homovanillic acid relates to higher burden of neuroinflammation and depression in people with HIV disease

BACKGROUND

HIV-related neuroinflammation has been proposed as a catalyst for dopaminergic dysregulation in mesocortical pathways, which may contribute to the pathogenesis of depression. Abnormalities in dopaminergic neurotransmission and depression are common in people with HIV (PWH), however the link between dopamine (DA) and depression in PWH is poorly characterized. This study investigated CSF dopaminergic biomarkers, specifically DA and its metabolite, homovanillic acid (HVA), and examined their relationship with depressive symptoms and CSF neuroinflammatory markers in PWH and HIV-seronegative (HIV-) individuals.

METHODS

Participants were 102 HIV- individuals and 123 PWH (mean age = 42) who underwent neuropsychiatric evaluations and lumbar puncture. Current depression severity was classified using the Beck Depression Inventory-II (BDI-II). CSF was assayed for DA and HVA using high performance liquid chromatography and neuroinflammatory markers using immunoassays. Linear regressions modelled BDI-II scores as a function of HIV, dopaminergic biomarker z-scores, and their interaction, controlling for psychosocial factors. Correlational analyses examined dopaminergic and neuroinflammatory relationships.

RESULTS

PWH had significantly higher BDI-II scores than HIV- participants. DA and HVA were not associated with HIV status but both significantly moderated the effect of HIV on BDI-II scores, such that PWH exhibited higher depressive symptoms than HIV- participants only at lower concentrations of HVA (z ≤ 0.06) and DA (z ≤ 0.11). In PWH only, lower HVA significantly correlated with higher BDI-II scores and higher neuroinflammation, including higher MCP-1 and IP-10.

CONCLUSIONS

Results suggest that the pathophysiology of depression in PWH differs from that in HIV- individuals. Specifically, lower central dopaminergic activity was selectively associated with greater depressive symptoms and neuroinflammation in PWH. With the rise in consideration of DA agonists for the treatment of depression, these results suggest that PWH may show a greater response to these agents than their HIV- peers.

Application of Noninvasive Vagal Nerve Stimulation to Stress-Related Psychiatric Disorders

BACKGROUND

Vagal Nerve Stimulation (VNS) has been shown to be efficacious for the treatment of depression, but to date, VNS devices have required surgical implantation, which has limited widespread implementation.

METHODS

New noninvasive VNS (nVNS) devices have been developed which allow external stimulation of the vagus nerve, and their effects on physiology in patients with stress-related psychiatric disorders can be measured with brain imaging, blood biomarkers, and wearable sensing devices. Advantages in terms of cost and convenience may lead to more widespread implementation in psychiatry, as well as facilitate research of the physiology of the vagus nerve in humans. nVNS has effects on autonomic tone, cardiovascular function, inflammatory responses, and central brain areas involved in modulation of emotion, all of which make it particularly applicable to patients with stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD) and depression, since dysregulation of these circuits and systems underlies the symptomatology of these disorders.

RESULTS

This paper reviewed the physiology of the vagus nerve and its relevance to modulating the stress response in the context of application of nVNS to stress-related psychiatric disorders.

CONCLUSIONS

nVNS has a favorable effect on stress physiology that is measurable using brain imaging, blood biomarkers of inflammation, and wearable sensing devices, and shows promise in the prevention and treatment of stress-related psychiatric disorders.

Analysis of the metabolic pathways affected by hot-humid or dry climate based on fecal metabolomics coupled with serum metabolic changes in broiler chickens

Air temperature and relative humidity (RH) are 2 important climatic elements that affect animal welfare and health. The prevailing hot and humid or dry climate is one of the major constraints for optimum poultry production, especially in the tropics and subtropical regions. Many studies have suggested that exposure to hot-humid or dry climate is associated with a high risk of metabolic imbalance; however, the underlying metabolic changes caused by low or high RH climate is not yet well understood. Therefore, we used a comprehensive ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry–based metabolic profiling of fecal samples to explore the effects of hot-humid and dry climate on metabolic pathways in broilers. A total of 180 twenty-eight-day-old Arbor Acres broilers were randomly allocated to 3 treatments, each containing 6 replicates of 10 birds per treatment, using a completely randomized design. Birds were reared at 35, 60, or 85% RH at 32°C (temperature increased by 3°C every 3 d from 20°C to 32°C within 15 d: 20°C, 23°C, 26°C, 29°C, 32°C) for 15 d. Results showed that significant changes in the levels of 36 metabolites were detected. Evidence of changes in gluconeogenesis associated to pyruvate metabolism, galactose metabolism, and ABC transporter was observed. In addition, hot-humid and dry stress also affected the protein translation process caused by aminoacyl-tRNA biosynthesis, which may be associated with protein synthesis and hormone secretion disorders. Furthermore, we observed significant changes in primary bile acid biosynthesis and taurine and hypotaurine metabolism, which indicated that fat synthesis was affected. We also observed significant changes in arginine and proline metabolism and histidine metabolism, which were associated with skin vasodilation and blood flow. These results provide biochemical insights into metabolic changes due to hot-humid or dry climate.

Gene signatures in peripheral blood immune cells related to insulin resistance and low tyrosine metabolism define a sub-type of depression with high CRP and anhedonia

Inflammation and altered glucose metabolism are two pathways implicated in the pathophysiology of major depressive disorder (MDD). We have previously shown that high inflammation as measured by C-reactive protein (CRP) in MDD patients is associated with symptoms of anhedonia, a core symptom of MDD, along with deficits in dopaminergic reward circuitry. Increased inflammation can shift metabolic demand and reprogram cellular energy sources, which may collectively impact the brain and reward processing to contribute to symptoms of anhedonia. To determine whether immunometabolic gene signatures were enriched in immune cells of depressed patients with increased inflammation and anhedonia, we examined whole-blood gene expression microarray (Illumina HumanHT-12) data from unmedicated, medically-stable patients with MDD (n = 93). Patients were considered to have increased inflammation based on High (>3mg/L) versus Low (≤3mg/L) plasma CRP, and further classified as having a self-reported phenotype of High (n = 30, 33rd percentile) versus Low (n = 32, 67th percentile) Anhedonia. Functional enrichment of gene pathways was assessed by Gene Set Enrichment Analysis (GSEA) using the KEGG pathway database. Pathways related to glucose metabolism (insulin signaling, insulin resistance, HIF-1, PI3K/AKT signaling), cancer (e.g., genes related to insulin and PI3K/AKT signaling), and inflammation (B cell, T cell and Fc receptor signaling) were specifically enriched in patients with both High CRP and High Anhedonia (all FDR q < 0.25). Within patients with High CRP in GSEA, the insulin signaling pathway was the top enriched pathway in patients with High versus Low Anhedonia (n = 10 and 9 respectively), which was driven by genes expressed predominantly in monocytes (z = 2.95, p < 0.01). Conversely, within patients with High Anhedonia, in addition to enrichment of immunometabolic pathways, the tyrosine metabolism pathway was also reduced in patients with High versus Low CRP (n = 20 and 10 respectively). Of note, enrichment of immunometabolic pathways was confirmed in complementary linear regression analyses examining pathways associated with a CRP-by-Anhedonia interaction term while controlling for clinical covariates in all patients (n = 93). These results indicate that increased glucose and low tyrosine metabolism define a subset of depressed patients with high inflammation and anhedonia. Enrichment of cancer-related pathways driven by metabolic genes also suggests a shift in immune cell metabolism from oxidative phosphorylation to glycolysis. Together these data suggest that anhedonia in MDD with high CRP involves both immunometabolic shifts and reduced dopamine precursor availability.

Neuroimmune Mechanisms and Sex/Gender-Dependent Effects in the Pathophysiology of Mental Disorders

Innate and adaptive immune mechanisms have emerged as critical regulators of CNS homeostasis and mental health. A plethora of immunologic factors have been reported to interact with emotion- and behavior-related neuronal circuits, modulating susceptibility and resilience to mental disorders. However, it remains unclear whether immune dysregulation is a cardinal causal factor or an outcome of the pathologies associated with mental disorders. Emerging variations in immune regulatory pathways based on sex differences provide an additional framework for discussion in these psychiatric disorders. In this review, we present the current literature pertaining to the effects that disrupted immune pathways have in mental disorder pathophysiology, including immune dysregulation in CNS and periphery, microglial activation, and disturbances of the blood-brain barrier. In addition, we present the suggested origins of such immune dysregulation and discuss the gender and sex influence of the neuroimmune substrates that contribute to mental disorders. The findings challenge the conventional view of these disorders and open the window to a diverse spectrum of innovative therapeutic targets that focus on the immune-specific pathophenotypes in neuronal circuits and behavior. SIGNIFICANCE STATEMENT: The involvement of gender-dependent inflammatory mechanisms on the development of mental pathologies is gaining momentum. This review addresses these novel factors and presents the accumulating evidence introducing microglia and proinflammatory elements as critical components and potential targets for the treatment of mental disorders.

Role of the eNOS Uncoupling and the Nitric Oxide Metabolic Pathway in the Pathogenesis of Autoimmune Rheumatic Diseases

Atherosclerosis and its clinical complications constitute the major healthcare problems of the world population. Due to the central role of endothelium throughout the atherosclerotic disease process, endothelial dysfunction is regarded as a common mechanism for various cardiovascular (CV) disorders. It is well established that patients with rheumatic autoimmune diseases are characterized by significantly increased prevalence of cardiovascular morbidity and mortality compared with the general population. The current European guidelines on cardiovascular disease (CVD) prevention in clinical practice recommend to use a 1,5-factor multiplier for CV risk in rheumatoid arthritis as well as in other autoimmune inflammatory diseases. However, mechanisms of accelerated atherosclerosis in these diseases, especially in the absence of traditional risk factors, still remain unclear. Oxidative stress plays the major role in the endothelial dysfunction and recently is strongly attributed to endothelial NO synthase dysfunction (eNOS uncoupling). Converted to a superoxide-producing enzyme, uncoupled eNOS not only leads to reduction of the nitric oxide (NO) generation but also potentiates the preexisting oxidative stress, which contributes significantly to atherogenesis. However, to date, there are no systemic analyses on the role of eNOS uncoupling in the excess CV mortality linked with autoimmune rheumatic diseases. The current review paper addresses this issue.