Depressive and anxiety symptoms in the early puerperium are related to increased degradation of tryptophan into kynurenine, a phenomenon which is related to immune activation

Role of Kynurenine and Its Derivatives in the Neuroimmune System

In recent years, there has been a growing realization of intricate interactions between the nervous and immune systems, characterized by shared humoral factors and receptors. This interplay forms the basis of the neuroimmune system, the understanding of which will provide insights into the pathogenesis of neurological diseases, in which the involvement of the immune system has been overlooked. Kynurenine and its derivatives derived from tryptophan have long been implicated in the pathogenesis of various neurological diseases. Recent studies have revealed their close association not only with neurological disorders but also with sepsis-related deaths. This review provides an overview of the biochemistry of kynurenine and its derivatives, followed by a discussion of their role via the modulation of the neuroimmune system in various diseases.

Selenium Intake and Postnatal Depression-A Short Review

Postnatal depression is a common and severe complication of childbirth. It is an important public health problem with significant implications for both mothers and children. The exact mechanisms underlying and the factors influencing the occurrence of postnatal depression remain unclear. The literature suggests that certain dietary deficiencies during pregnancy and the postnatal period may contribute to a greater risk of maternal depression. This review focuses on the role of selenium in postnatal depression. It collects evidence from published interventional and observational studies investigating the relationship between selenium intake during the antenatal and postnatal periods and the mental status of postpartum women and summarises information about biological mechanisms that may underlie the association between selenium status and postnatal depression. The review includes studies identified through electronic searches of Medline (via PubMed) and Google Scholar databases until December 2023. Despite the small number of relevant studies and their potential methodological limitations, the findings suggest that optimizing selenium status may support the prevention and treatment of postnatal depression. Further longitudinal and interventional studies are necessary to confirm the clinical significance of these effects.

Neuroimmune modulation by tryptophan derivatives in neurological and inflammatory disorders

The nervous and immune systems are highly developed, and each performs specialized physiological functions. However, they work together, and their dysfunction is associated with various diseases. Specialized molecules, such as neurotransmitters, cytokines, and more general metabolites, are essential for the appropriate regulation of both systems. Tryptophan, an essential amino acid, is converted into functional molecules such as serotonin and kynurenine, both of which play important roles in the nervous and immune systems. The role of kynurenine metabolites in neurodegenerative and psychiatric diseases has recently received particular attention. Recently, we found that hyperactivity of the kynurenine pathway is a critical risk factor for septic shock. In this review, we first outline neuroimmune interactions and tryptophan derivatives and then summarized the changes in tryptophan metabolism in neurological disorders. Finally, we discuss the potential of tryptophan derivatives as therapeutic targets for neuroimmune disorders.

Inflammatory biomarkers and perinatal depression: A systematic review

BACKGROUND

Approximately 10 to 20% of pregnant women worldwide experience perinatal depression (PND), a depressive episode with onset during pregnancy or after childbirth. We performed a systematic review to identify, summarize and discuss studies on inflammatory biomarkers described in relation to PND.

METHOD

Inclusion criteria defined the selection of observational studies written in English, French, Spanish or Portuguese, that evaluate analytical levels of inflammatory molecules (protein levels) in biological fluids in women, with a diagnosis of depression using ICD/DSM diagnostic criteria or depressive symptoms assessed by standardized psychometric instruments, during pregnancy and/or postpartum. Case reports, experimental studies, reviews, qualitative analysis, meta-analysis, gray literature or replicated data were excluded. Three electronic databases were used for search (Pubmed, Web of Science and PsychInfo) and quality assessment of selected studies were performed using the Newcastle-Ottawa Scale. Data extraction included study design; number of subjects; obstetric information; tools and timepoints of depression and inflammatory markers assessment.

RESULTS

56 studies (sample size for cross-sectional and case-control studies ranging from 10 to 469; sample size for longitudinal studies ranging from 26 to 467), where the major aim was to analyze the association between depression and inflammatory biomarkers during pregnancy and postpartum period were included in this systematic review. Overall, the findings of our systematic review lend support to the hypothesis that several inflammatory markers may be associated with peripartum depressive symptoms. The associations were somewhat different looking at pregnancy compared to the delivery time-point and postpartum, and mainly referred to increased levels of IL-6, IL-8, CRP and TNF-α among depressed.

DISCUSSION

In summary, our systematic review findings provide evidence supporting the hypothesis that several inflammatory markers may correlate with peripartum depressive symptoms. However, our work also highlighted notable differences in the timing of biological sampling for inflammatory markers and in the methodologies used to assess depression during the perinatal period. Additionally, variations were observed in how inflammatory biomarkers and depression were approached, including their classification as exposure or outcome variables, and the timing of assessments. It is essential for future research to investigate the influence of biological fluids and the timing of assessments for both inflammatory biomarkers and depression to gain a deeper understanding of their association. This comprehensive exploration is pivotal for elucidating the intricate relationship between inflammation and perinatal depression.

Urine Metabolite Analysis to Identify Pathomechanisms of Long COVID: A Pilot Study

Background

Around 10% of people who had COVID-9 infection suffer from persistent symptoms such as fatigue, dyspnoea, chest pain, arthralgia/myalgia, sleep disturbances, cognitive dysfunction and impairment of mental health. Different underlying pathomechanisms appear to be involved, in particular inflammation, alterations in amino acid metabolism, autonomic dysfunction and gut dysbiosis.

Aim

As routine tests are often inconspicuous in patients with Long COVID (LC), similarly to patients suffering from myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), accessible biomarkers indicating dysregulation of specific pathways are urgently needed to identify underlying pathomechanisms and enable personalized medicine treatment. Within this pilot study we aimed to proof traceability of altered metabolism by urine analysis.

Patients and Methods

Urine metabolome analyses were performed to investigate the metabolic signature of patients with LC (n = 25; 20 women, 5 men) in comparison to healthy controls (Ctrl, n = 8; 7 women, 1 man) and individuals with ME/CFS (n = 8; 2 women, 6 men). Concentrations of neurotransmitter precursors tryptophan, phenylalanine and their downstream metabolites, as well as their association with symptoms (fatigue, anxiety and depression) in the patients were examined.

Results and Conclusion

Phenylalanine levels were significantly lower in both the LC and ME/CFS patient groups when compared to the Ctrl group. In many LC patients, the concentrations of downstream metabolites of tryptophan and tyrosine, such as serotonin, dopamine and catecholamines, deviated from the reference ranges. Several symptoms (sleep disturbance, pain or autonomic dysfunction) were associated with certain metabolites. Patients experiencing fatigue had lower levels of kynurenine, phenylalanine and a reduced kynurenine to tryptophan ratio (Kyn/Trp). Lower concentrations of gamma-aminobutyric acid (GABA) and higher activity of kynurenine 3-monooxygenase (KMO) were observed in patients with anxiety. Conclusively, our results suggest that amino acid metabolism and neurotransmitter synthesis is disturbed in patients with LC and ME/CFS. The identified metabolites and their associated dysregulations could serve as potential biomarkers for elucidating underlying pathomechanisms thus enabling personalized treatment strategies for these patient populations.

Effects of different doses of esketamine intervention on postpartum depressive symptoms in cesarean section women: A randomized, double-blind, controlled clinical study

BACKGROUND

The optimal dosage and method of esketamine for postpartum depressive symptoms (PDS) are unclear. We conducted a randomized controlled trial (RCT) to investigate the effect of different doses of esketamine on PDS in women undergoing cesarean section, with evidence of prenatal depression.

METHODS

The three groups were high- (2 mg kg-1) and low-dose (1 mg kg-1) esketamine via patient controlled intravenous analgesia (PCIA), following an initial intravenous infusion of 0.25 mg kg-1 esketamine, compared to placebo (0.9 % saline infusion). All groups also received the sufentanil (2.2 μg kg-1). The primary outcome was the incidence of PDS at 7 and 42 days postpartum. The secondary outcomes were: the remission from depression and total EPDS scores at 7 days and 42 days postpartum; mean change from baseline in the EPDS score; postoperative analgesia.

RESULTS

i). 0.25 mg kg-1 of esketamine intravenous infusion combined with 1 mg kg-1 (n = 99) or 2 mg kg-1 (n = 99) esketamine PCIA reduces PDS incidence at 7 days postpartum (p < 0.05), with high-dose esketamine PCIA also reduces PDS incidence 42 days postpartum (p < 0.05), compared to placebo (n = 97). ii). Low- and high-dose esketamine PCIA lowers NRS scores at rest within 48 h postoperatively (p < 0.01), with high-dose esketamine also reducing the NRS score during movement at 48 h postoperatively (p = 0.018). iii). Neither high- nor low-dose esketamine PCIA increased postoperative adverse reactions (p > 0.05).

CONCLUSIONS

Esketamine (0.25 mg kg-1) intravenous infusion combined with 1 mg kg-1 or 2 mg kg-1 esketamine PCIA seems safe and with few adverse effects in the management of PDS and pain in women undergoing cesarean section.

LIMITATIONS

The tolerability and safety of esketamine requires further investigation based on more specific scales; the transient side effects of esketamine could have biased the staff and patients.

TRIAL REGISTRATION

ChiCTR-ROC-2000039069.

Anxiety due to Long COVID is partially driven by activation of the tryptophan catabolite (TRYCAT) pathway

This study examines whether activation of the tryptophan catabolite (TRYCAT) pathway is associated with anxiety symptoms due to Long COVID. We selected 90 participants, 60 Long COVID patients and 30 individuals without any symptoms following acute COVID-19 infection. Using cluster analysis and the Hamilton Anxiety Rating scale (HAMA) score, the pure HAMA anxiety score, serum tryptophan (TRP) and kynurenine (KYN), the KYN/TRP ratio (all measured during Long COVID), and oxygen saturation (SpO2) (measured during the acute phase of COVID-19), we were able to classify Long COVID patients into two distinct clusters with an adequate silhouette cohesion and separation index (0.58): cluster 1 (n = 61) and cluster 2 (n = 29). Cluster 2 patients had lower SpO2 and TRP levels, as well as higher KYN, KYN/TRP ratio, and HAMA scores than cluster 1. Regression analysis revealed that the KYN/TRP ratio explained 14.4 % of the variance in the HAMA score (F = 14.81, df = 1/88, p = 0.001). In addition, regression analysis revealed that SpO2 partially explained the variance in serum TRP (r = 0.396, p = 0.005), KYN/TRP ratio (r = - 0.248, p = 0.018), and the HAMA score (r = - 0.279, p = 0.008). The current data imply that decreased SpO2 during the acute phase of COVID-19 infection is predictive of anxiety caused by Long COVID. Our data reveal that around 32 % of Long COVID patients have elevated IDO activity in association with elevated anxiety.

Depression, anxiety, insomnia and interleukins in the early postpartum period

Background

Some new mothers have been shown to suffer from anxiety and depression associated with insomnia during the postpartum period. Our study assessed the impact of demographic, psychopathological, and biochemical factors on the incidence of depression in women during the early postpartum period.

Methods

A total of 119 women were evaluated at 24-48 h postpartum with the following psychometric scales: Hamilton Depression Rating Scale (HDRS), Edinburgh Postnatal Depression Scale (EPDS), Hamilton Anxiety Rating Scale (HARS) and Athens Insomnia Scale (AIS). In addition, blood was drawn to assay interleukin 6 (IL-6) and interleukin 10 (IL-10).

Results

The factors that had the greatest impact on the risk of postpartum depression detected with the HDRS were high HARS scores and evidence of insomnia in the AIS. There were no significant differences in IL-6 or IL-10 levels in women with and without depression (based on either HDRS or EPDS scores) and insomnia (based on AIS) after childbirth. Considering demographic factors, divorced and single women were shown to be at higher risk of postpartum depression (based on EPDS scores).

Limitations

Small sample size and short observation span.

Conclusion

This study highlights the relationship between postpartum depression and both anxiety and insomnia and emphasises the importance to assess symptoms of anxiety and sleep quality as part of screening in women at risk of postpartum depression.

Platelets bridging the gap between gut dysbiosis and neuroinflammation in stress-linked disorders: A narrative review

In this narrative review, we examine the association between gut dysbiosis, neuroinflammation, and stress-linked disorders, including depression, anxiety, and post-traumatic stress disorder (PTSD), and investigate whether tryptophan (TRP) metabolism and platelets play a role in this association. The mechanisms underlying the aetiology of stress-linked disorders are complex and not yet completely understood. However, a potential link between chronic inflammation and these disorders may potentially be found in TRP metabolism and platelets. By critically analysing existing literature on platelets, the gut microbiome, and stress-linked disorders, we hope to elicit the role of platelets in mediating the effects on serotonin (5-HT) levels and neuroinflammation. We have included studies specifically investigating platelets and TRP metabolism in relation to inflammation, neuroinflammation and neuropsychiatric disorders. Alteration in microbial composition due to stress could contribute to increased intestinal permeability, facilitating the translocation of microbial products, and triggering the release of pro-inflammatory cytokines. This causes platelets to become hyperactive and secrete 5-HT into the plasma. Increased levels of pro-inflammatory cytokines may also lead to increased permeability of the blood-brain barrier (BBB), allowing inflammatory mediators entry into the brain, affecting the balance of TRP metabolism products, such as 5-HT, kynurenic acid (KYNA), and quinolinic acid (QUIN). These alterations may contribute to neuroinflammation and possible neurological damage. Furthermore, platelets can cross the compromised BBB and interact with astrocytes and neurons, leading to the secretion of 5-HT and pro-inflammatory factors, exacerbating inflammatory conditions in the brain. The mechanisms underlying neuroinflammation resulting from peripheral inflammation are still unclear, but the connection between the brain and gut through the bloodstream could be significant. Identifying peripheral biomarkers and mechanisms in the plasma that reflect neuroinflammation may be important. This review serves as a foundation for further research on the association between the gut microbiome, blood microbiome, and neuropsychiatric disorders. The integration of these findings with protein and metabolite markers in the blood may expand our understanding of the subject.

Psychiatric disorders during pregnancy in asymptomatic and mildly symptomatic SARS-CoV-2 positive women: Prevalence and effect on outcome

The effect of psychiatric comorbidity on pregnancy outcome among SARS-CoV-2 positive women with asymptomatic and mildly symptomatic infections remains largely unknown. We reviewed the electronic medical records of all pregnant women who received care at Mayo Health System and tested positive for SARS-CoV-2 (RT-PCR) from March 2020 through October 2021. Among 789 patients, 34.2% (n = 270) had psychiatric comorbidity. Of those with psychiatric comrobidity, 62.2% (n = 168) had depression prior to pregnancy, and 5.2% (n = 14) reported new-onset depression during pregnancy. Before pregnancy, 65.6% (n = 177) had anxiety, and 4.4% (n = 12) developed anxiety during pregnancy Thirteen percent of SARS-CoV-2 positive pregnant women (n = 108) received psychotropic medication during pregnancy. In addition, 6.7% (n = 18) and 10.7% (n = 29) of pregnant women with psychiatric comorbidity had documented nicotine, cannabis and/ or illicit substance use during and prior to pregnancy, respectively. We depicted a significantly higher risk for cesarean delivery [35.6% vs. 24.9%) in asymptomatic and mildly symptomatic SARS-CoV-2 positive pregnant women with psychiatric comorbidity. In conclusion, the prevalence rates of depression, anxiety, and prescribed antidepressant medications during pregnancy among asymptomatic and mildly symptomatic SARS-CoV-2 infected women were substantially higher than average, which negatively impacted pregnancy and neonatal outcomes.

IDO/Kynurenine; novel insight for treatment of inflammatory diseases

Inflammation and oxidative stress play pivotal roles in pathogenesis of many diseases including cancer, type 2 diabetes, cardiovascular disease, atherosclerosis, neurological diseases, and inflammatory diseases such as inflammatory bowel disease (IBD). Inflammatory mediators such as interleukins (ILs), interferons (INF-s), and tumor necrosis factor (TNF)-α are related to an extended chance of inflammatory diseases initiation or progression due to the over expression of the nuclear factor Kappa B (NF-κB), signal transducer of activators of transcription (STAT), nod-like receptor family protein 3 (NLRP), toll-like receptors (TLR), mitogen-activated protein kinase (MAPK), and mammalian target of rapamycin (mTOR) pathways. These pathways are completely interconnected. Theindoleamine 2,3 dioxygenase (IDO) subset of the kynurenine (KYN) (IDO/KYN), is a metabolic inflammatory pathway involved in production of nicotinamide adenine dinucleotide (NAD + ). It has been shown that IDO/KYN actively participates in inflammatory processes and can increase the secretion of cytokines that provoke inflammatory diseases. Data were extracted from clinical and animal studies published in English between 1990-April 2022, which were collected from PubMed, Google Scholar, Scopus, and Cochrane library. IDO/KYN is completely associated with inflammatory-related pathways, thus leading to the production of cytokines such as TNF-α, IL-1β, and IL-6, and ultimately development and progression of various inflammatory disorders. Inhibition of the IDO/KYN pathway might be a novel therapeutic option for inflammatory diseases. Herein, we gathered data on probable interactions of the IDO/KYN pathway with induction of some inflammatory diseases.

Tryptophan degradation enzymes expression in the placenta and the Kynurenine/Tryptophan ratio in maternal plasma after elective cesarean section

Indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO) metabolize tryptophan in the kynurenine pathway. We evaluated these enzymes' mRNA expression in maternal and fetal sides of the placenta of uncomplicated, unlabored full-term pregnancies after elective cesarean section and compared it with that of placentas obtained from vaginal delivery. Tryptophan and kynurenine plasmatic levels after cesarean section were measured, to investigate their possible correlation with IDO1 and TDO mRNA (TDO2) expression. The results suggested that IDO1 and TDO2 expression was higher in the maternal side of the placenta and that labor significantly affects TDO2 expression and the plasma Kynurenine/Tryptophan ratio.

Gut microbiota: A new target for traditional Chinese medicine in the treatment of depression

ETHNIC PHARMACOLOGICAL RELEVANCE

The causes of depression are complex. Many factors are involved in its pathogenesis, including the individual's biological and social environment. Although numerous studies have reported that the gut microbiota plays a significant role in depression, drugs that regulate the gut microbiota to treat depression have not yet been comprehensively reviewed. At the same time, more and more attention has been paid to the characteristics of traditional Chinese medicine (TCM) in improving depression by regulating gut microbiota. In ancient times, fecal microbiota transplantation was recorded in TCM for the treatment of severe diseases. There are also records in Chinese ancient books about the use of TCM to adjust gut microbiota to treat diseases, which has opened up a unique research field in TCM. Therefore, this article focuses on the pharmacological effects, targets, and mechanisms of TCM in improving depression by mediating the influence of gut microbiota.

AIM OF THIS REVIEW

To summarize the role the gut microbiota plays in depression, highlight potential regulatory targets, and elucidate the anti-depression mechanisms of TCMs through regulation of the gut microbiota.

METHODS

A systematic review of 256 clinical trials and pharmaceutical studies published until June 2022 was conducted in eight electronic databases (Web of Science, PubMed, SciFinder, Research Gate, ScienceDirect, Google Scholar, Scopus, and China Knowledge Infrastructure), according to the implemented PRISMA criteria, using the search terms "traditional Chinese medicine," "depression," and "gut microbiota."

RESULTS

Numerous studies reported the effects of different gut bacteria on depression and that antidepressants work through the gut microbiota. TCM preparations based on compound Chinese medicine, the Chinese Materia Medica, and major bioactive components exerted antidepressant-like effects by improving levels of neurotransmitters, short-chain fatty acids, brain-derived neurotrophic factor, kynurenine, and cytokines via regulation of the gut microbiota.

CONCLUSION

This review summarized the anti-depression effects of TCM on the gut microbiota, providing evidence that TCMs are safe and effective in the treatment of depression and may provide a new therapeutic approach.

Exploration for biomarkers of postpartum depression based on metabolomics: A systematic review

BACKGROUND

Postpartum depression (PPD) is the most frequent psychiatric complication during the postnatal period and its mechanisms are not fully understood. Metabolomics, can quantitatively measure metabolites in a high-throughput method, and thus uncover the underlying pathophysiology of disease.

OBJECTIVES

In this study, we reviewed metabolomics studies conducted on PPD, aiming to understand the changes of metabolites in PPD patients and analyze the potential application of metabolomics in PPD prediction and diagnosis.

METHODS

Relevant articles were searched in PubMed, Google scholar, and Web of Science databases from January 2011 to July 2022. The metabolites involved were systematically examined and compared. MetaboAnalyst online software was applied to analyze metabolic pathways.

RESULTS

A total of 14 papers were included in this study. There were several highly reported metabolites, such as kynurenine, kynurenic acid, and eicosapentaenoic acid. Dysregulation of metabolic pathways involved amino acids metabolism, fatty acids metabolism, and steroids metabolism.

LIMITATIONS

The included studies are relatively inadequate, and further work is needed.

CONCLUSIONS

This study summarized significant metabolic alterations that provided clues for the prediction, diagnosis, and pathogenesis of PPD.

Ovarian status modulates endocrine and neuroinflammatory responses to a murine mammary tumor

Patients with breast cancer have increased circulating inflammatory markers and mammary tumors increase neuroinflammation in rodent models. Menopausal status is not only important in the context of breast cancer as circulating estrogen influences tumor progression, but also because estrogen is anti-inflammatory and an essential modulator of endocrine function in the brain and body. Here, we manipulated "menopause" status (ovary-intact and ovariectomized) in an estrogen receptor (ER)+ mouse mammary tumor model to determine the extent to which ovarian status modulates: 1) tumor effects on estrogen concentrations and signaling in the brain, 2) tumor effects on estrogen-associated neurobiology and inflammation, and 3) the ability for tumor resection to resolve the effects of a tumor. We hypothesized that reduced circulating estradiol (E2) after an ovariectomy exacerbates tumor-induced peripheral and central inflammation. Notably, we observed ovarian-dependent modulation on tumor-induced peripheral outcomes, including E2-dependent processes and, to a lesser degree, circulating inflammatory markers. In the brain, ovariectomy exacerbated neuroinflammatory markers in select brain regions and modulated E2-related neurobiology due to a tumor and/or resection. Overall, our data suggest that ovarian status has moderate implications for tumor-induced alterations in neuroendocrinology and neuroinflammation and mild effects on peripheral inflammatory outcomes in this murine mammary tumor model.

Behavioral, Hormonal, and Serotonergic Responses to Different Restricted Feeding Schedules in Rats

To determine the effect of long-term restricted feeding schedules on behavior, serotonergic responses, and neuro-endocrine functions, metabolism of serotonin (5-HT) in the striatum, expression of serotonin-1A (5-HT1A) auto-receptor in the raphe nuclei and circulating levels of leptin and corticosterone were determined in female Wistar rats kept on excessive food restriction schedule. Due to a role of dietary deficiency of tryptophan (Trp) in influencing serotonergic neurotransmission, circulating levels of Trp were also determined. Estimations were done in 2 different restricted feeding models: time-restricted feeding (TRF) and diet restricted (DR). TRF animals were given access to food ad libitum only for 2 hours/day. The DR animals were given a small calculated amount of food each day. We found that chronic food restriction for 5 weeks cause a significant decrease in the body weight and produced hyperactivity in both, TRF and DR animals. Levels of Trp were declined in circulation and in the striatum. Similarly, the levels of 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were decreased in the striatum. Also, the expression of 5-HT1A auto-receptor was declined in the raphe nuclei. These changes in 5-HT metabolism and 5-HT1A auto-receptor expression were more profound in DR animals as compare to TRF animals. Similarly, hypoleptinemia and increased corticosterone found in both models was higher in DR animals. Effect of dietary deficiency of Trp in the modulation of striatal 5-HT metabolism and its consequences on circulating leptin and corticosterone are discussed.

Shuangxinfang Prevents S100A9-Induced Macrophage/Microglial Inflammation to Improve Cardiac Function and Depression-Like Behavior in Rats After Acute Myocardial Infarction

Background: Depression is a common complication of cardiovascular disease, which deteriorates cardiac function. Shuangxinfang (psycho-cardiology formula, PCF) was reported to alleviate myocardial ischemia injury and improve depression-like behavior. Interestingly, our previous proteomics study predicted that the protein S100A9 appeared as an important target, and macrophage/microglial inflammation might be involved in the process of PCF improving depression induced by acute myocardial infarction (AMI). This study aims to validate the proteomics results.

Methods: AMI rat models were established in vivo, followed by the administration of PCF or ABR-215757 (also named paquinimod, inhibiting S100A9 binding to TLR4) for 5 days. Forced swimming test (FST) and open field test (OFT) were applied to record depression-like behavior, and echocardiography was employed to evaluate cardiac function. Morphological changes of cardiomyocytes were assessed by HE staining and TUNEL staining on day 7 after cardiac surgery, as well as Masson trichrome staining on day 21. Hippocampal neurogenesis was determined by Nissl staining, while 5-hydroxytryptamine (5-HT), tryptophan/kynurenine ratio, and brain-derived neurotrophic factor (BDNF) in the hippocampus were analyzed as biochemical indicators of depression. We employed RT-qPCR, western blotting, and immunofluorescence to detect the expression of pathway-related genes and proteins. Myocardial and hippocampal expression of inflammatory factors were performed by ELISA. The activation of macrophage and microglia was assessed via immunoreaction using CD68 and Iba1, respectively. For in vitro confirmation, BV2 cells were primed with recombinant protein S100A9 and then treated with PCF serum or ferulic acid to determine alterations in microglial inflammation.

Results: Rats in the AMI group showed heart function deterioration and depression-like behavior. Coronary ligation not only brought about myocardial inflammation, cell apoptosis, and fibrosis but also reduced the neurogenesis, elevated the tryptophan/kynurenine ratio, and decreased the content of 5-HT. PCF could ameliorate the pathological and phenotypic changes in the heart and brain and inhibit the expression of the S100A9 protein, the activation of the microglial cell, and the secretion of IL-1β and TNF-α raised by AMI. ABR-215757 showed therapeutic effect and molecular biological mechanisms similar to PCF. Treatment with PCF serum or ferulic acid in vitro was proved to efficiently block the hyperactivation of BV2 cells and increment of cytokine contents induced by recombinant protein S100A9.

Conclusion: We identify S100A9 as a novel and potent regulator of inflammation in both the heart and brain. Macrophage/microglia inflammation mediated by S100A9 is considered a pivotal pathogenic in depression after AMI and a major pathway for the treatment of PCF, suggesting that PCF is a promising therapeutic candidate for psycho-cardiology disease.

Microbiome abnormalities as a possible link between diabetes mellitus and mood disorders: Pathophysiology and implications for treatment

Diabetes mellitus and mental health disorders create an immense burden on society worldwide. Knowledge of the cellular and biochemical connections linking these two pathologies has broadened and the mechanism for diet-induced shifts in the microbiota has become more refined. However, there remains limited understanding of the mechanism wherein changes in the microbiota affect the development and severity of these diseases and their interconnectedness. This review examines current literature to highlight a potential mechanism that links specific changes in the microbiome to mental health disorders and diabetes mellitus. Novel data indicate that alterations in the abundance and concentration of bacterium in the gut result in an elevated risk for developing mental and metabolic disorders. Through the mechanisms and downstream effects of short-chain fatty acids and the tryptophan metabolizing pathway, the onset of diabetes is shown to directly affect the development of mental health disorders. This paper provides a possible physiological mechanism connecting these two disorders, which could inform future research and policy decisions limiting the global impact of these diseases.

The impact of obesity-related neuroinflammation on postpartum depression: A narrative review

Obesity is currently one of the most serious health problems, affecting 13% of the world's adult population. Obesity is characterized by persistent low-grade chronic inflammation that assumes systemic proportions and triggers several associated metabolic diseases. Furthermore, obesity has been associated with an increased occurrence of central disorders such as impaired cognitive function, reward system dysfunction, and depression. In summary, there is a quantitative reduction in the release of neurotransmitters in depression. Postsynaptic cells capture lower concentrations of neurotransmitters, which leads to a functional reduction in the central nervous system (CNS). Globally, approximately 15-65% of women experience depressive symptoms during pregnancy, depending on their location. Depressive symptoms persist in some women, leading to postpartum depression (PPD). Thus, obesity may be considered a risk factor for PPD development. This study aimed to synthesize studies on the impact of obesity-related neuroinflammation and PPD. We conducted a narrative review of the relevant literature. The search was performed in electronic databases, specifically PubMed, selecting articles in English published from 2014 to 2021 using the narrative review methodology.

Inflammation-driven brain and gut barrier dysfunction in stress and mood disorders

Regulation of emotions is generally associated exclusively with the brain. However, there is evidence that peripheral systems are also involved in mood, stress vulnerability vs. resilience, and emotion-related memory encoding. Prevalence of stress and mood disorders such as major depression, bipolar disorder, and post-traumatic stress disorder is increasing in our modern societies. Unfortunately, 30%-50% of individuals respond poorly to currently available treatments highlighting the need to further investigate emotion-related biology to gain mechanistic insights that could lead to innovative therapies. Here, we provide an overview of inflammation-related mechanisms involved in mood regulation and stress responses discovered using animal models. If clinical studies are available, we discuss translational value of these findings including limitations. Neuroimmune mechanisms of depression and maladaptive stress responses have been receiving increasing attention, and thus, the first part is centered on inflammation and dysregulation of brain and circulating cytokines in stress and mood disorders. Next, recent studies supporting a role for inflammation-driven leakiness of the blood-brain and gut barriers in emotion regulation and mood are highlighted. Stress-induced exacerbated inflammation fragilizes these barriers which become hyperpermeable through loss of integrity and altered biology. At the gut level, this could be associated with dysbiosis, an imbalance in microbial communities, and alteration of the gut-brain axis which is central to production of mood-related neurotransmitter serotonin. Novel therapeutic approaches such as anti-inflammatory drugs, the fast-acting antidepressant ketamine, and probiotics could directly act on the mechanisms described here improving mood disorder-associated symptomatology. Discovery of biomarkers has been a challenging quest in psychiatry, and we end by listing promising targets worth further investigation.

Effect of Curcumin in Experimental Pulmonary Tuberculosis: Antimycobacterial Activity in the Lungs and Anti-Inflammatory Effect in the Brain

Tuberculosis (TB) is one of the ten leading causes of death worldwide. Patients with TB have been observed to suffer from depression and anxiety linked to social variables. Previous experiments found that the substantial pulmonary inflammation associated with TB causes neuroinflammation, neuronal death, and behavioral impairments in the absence of brain infection. Curcumin (CUR) is a natural product with antioxidant, anti-inflammatory and antibacterial activities. In this work, we evaluated the CUR effect on the growth control of mycobacteria in the lungs and the anti-inflammatory effect in the brain using a model of progressive pulmonary TB in BALB/c mice infected with drug-sensitive mycobacteria (strain H37Rv). The results have shown that CUR decreased lung bacilli load and pneumonia of infected animals. Finally, CUR significantly decreased neuroinflammation (expression of TNFα, IFNγ and IL12) and slightly increased the levels of nuclear factor erythroid 2-related to factor 2 (Nrf2) and the brain-derived neurotrophic factor (BDNF) levels, improving behavioral status. These results suggest that CUR has a bactericidal effect and can control pulmonary mycobacterial infection and reduce neuroinflammation. It seems that CUR has a promising potential as adjuvant therapy in TB treatment.

Inflammatory and neurodegenerative pathophysiology implicated in postpartum depression

Postpartum depression (PPD) is the most common psychiatric complication associated with pregnancy and childbirth with debilitating symptoms that negatively impact the quality of life of the mother as well as inflict potentially long-lasting developmental impairments to the child. Much of the theoretical pathophysiology put forth to explain the emergence of PPD overlaps with that of major depressive disorder (MDD) and, although not conventionally described in such terms, can be seen as neurodegenerative in nature. Framing the disorder from the perspective of the well-established inflammatory theory of depression, symptoms are thought to be driven by dysregulation, and subsequent hyperactivation of the body's immune response to stress. Compounded by physiological stressors such as drastic fluctuations in hormone signaling, physical and psychosocial stressors placed upon new mothers lay bare a number of significant vulnerabilities, or points of potential failure, in systems critical for maintaining healthy brain function. The inability to compensate or properly adapt to meet the changing demands placed upon these systems has the potential to damage neurons, hinder neuronal growth and repair, and disrupt neuronal circuit integrity such that essential functional outputs like mood and cognition are altered. The impact of this deterioration in brain function, which includes depressive symptoms, extends to the child who relies on the mother for critical life-sustaining care as well as important cognitive stimulation, accentuating the need for further research.

Metabolite trajectories across the perinatal period and mental health: A preliminary study of tryptophan-related metabolites, bile acids and microbial composition

Depression and anxiety during pregnancy and postpartum are common, but affected women differ in timing, trajectories, and extent of symptoms. The objective of this pilot, feasibility study is to analyze trajectories of serotonin and tryptophan-related metabolites, bile acid metabolites, and microbial composition, in relation to psychiatric history and current symptoms across the perinatal period. Serum and fecal samples were collected from 30 women at three times points in the perinatal period and assayed with LC-MS/MS and 16S sequencing respectively. We defined mean trajectories for each metabolite, clustered individuals by metabolite trajectories, tested associations between metabolites, and examined metabolite levels in relation to microbial composition. Findings of note include: (1) changes in kynurenine and the ratio of kynurenic acid to kynurenine from second trimester to third trimester were strongly associated with baseline primary and secondary bile acids. (2) Secondary bile acid UDCA and its conjugated forms were associated with lower bacterial diversity and levels of Lachnospiraceae, a taxa known to produce Short Chain Fatty Acids. (3) History of anxiety was associated with UDCA levels, but history of major depression was not associated with any of the bile acids. (4) There was a trend towards lower dietary fiber for those with history of anxiety or depression. Overall, our results reveal substantial temporal variation in tryptophan-related metabolites and in bile acid metabolites over the perinatal period, with marked inter-individual variability. Trajectories of TRP -related metabolites, primary and secondary bile acids, and the absence or presence of microbes that produce Short Chain Fatty Acids (SCFAs) considered in concert have the potential to differentiate individuals based on perinatal adaptations that may impact mental and overall health.

Covid-19 interface with drug misuse and substance use disorders

The coronavirus disease 2019 (Covid-19) pandemic intensified the already catastrophic drug overdose and substance use disorder (SUD) epidemic, signaling a syndemic as social isolation, economic and mental health distress, and disrupted treatment services disproportionally impacted this vulnerable population. Along with these social and societal factors, biological factors triggered by intense stress intertwined with incumbent overactivity of the immune system and the resulting inflammatory outcomes may impact the functional status of the central nervous system (CNS). We review the literature concerning SARS-CoV2 infiltration and infection in the CNS and the prospects of synergy between stress, inflammation, and kynurenine pathway function during illness and recovery from Covid-19. Taken together, inflammation and neuroimmune signaling, a consequence of Covid-19 infection, may dysregulate critical pathways and underlie maladaptive changes in the CNS, to exacerbate the development of neuropsychiatric symptoms and in the vulnerability to develop SUD. This article is part of the special Issue on 'Vulnerabilities to Substance Abuse'.

Are alterations in estradiol, cortisol, and inflammatory cytokines associated with depression during pregnancy and postpartum? An exploratory study

Background

Pregnant veterans are a subpopulation known to be at elevated risk of developing mental health symptoms, such as depression and suicidal ideation. Inflammation has been associated with depression, specifically during the perinatal period. Critical changes in estradiol, cortisol, and inflammatory cytokines are necessary for the progression of a healthy pregnancy, which are then rapidly altered in the postpartum period. We explored changes in estradiol, cortisol, and pro-inflammatory cytokines relative to depressive symptoms and suicidal thoughts across pregnancy and postpartum in this pilot and feasibility study.

Methods

We measured estradiol, cortisol, and the inflammatory cytokines IL-1β, IL-6, IL-8, IFN-γ, and TNF-α in 18 pregnant veterans and analyzed the data using descriptive statistics, dependent t-tests, and correlation analyses. We assessed depression severity with the Edinburgh Postnatal Depression Scale and suicidality with the Columbia-Suicide Severity Rating Scale. Thirteen of the women repeated assessments in the early postpartum period at an average of 6.7 weeks after birth.

Results

As anticipated, estradiol (t(12) ​= ​12.47, p ​< ​.001) and cortisol (t(12) ​= ​9.43, p ​< ​.001) significantly decreased from pregnancy to postpartum. There were no differences in the means of gestational and postpartum IL-1β, IL-6, TNF-α, or IFN-γ, but IL-8 was significantly increased from pregnancy to postpartum (t(12) ​= ​-4.60, p ​= ​.001). Estradiol during pregnancy was positively correlated with IL-6 levels both during pregnancy (r _p  ​= ​.656, p ​= ​.008) and postpartum (r ​= ​0.648, p ​= ​.023). Elevated IL-1β was associated with suicidal thoughts during pregnancy (r ​= ​0.529, p ​= ​.029). Although not statistically significant, depressive symptom severity trended towards a positive association with larger increases in IL-1β (r ​= ​0.535, p ​= ​.09) and TNF-α (r ​= ​0.501, p ​= ​.08) from pregnancy to postpartum.

Conclusion

This preliminary study suggests the feasibility of our approach for exploring a complex interplay between hormonal and pro-inflammatory changes from pregnancy to postpartum, and their relationship with depressive symptoms. Given our small sample and the relatively exploratory nature of our analyses, additional investigation focusing on hormonal and inflammatory changes and their potential associations with perinatal mental health is necessary to confirm and extend our preliminary findings and examine additional potential covariates.

Exploring the roles of tryptophan metabolism in MS beyond neuroinflammation and neurodegeneration: A paradigm shift to neuropsychiatric symptoms

The metabolism of tryptophan through the kynurenine pathway (KP) has been increasingly recognised in contributing to disease progression in the autoimmune and inflammatory disease multiple sclerosis (MS). In this review, the roles of inflammation and the KP are recontextualised to better understand the aetiology of the neuropsychiatric symptoms (depression, postpartum depression, suicidality, fatigue and cognitive dysfunction) in MS. These symptoms will be discussed in the context of cytokine-induced sickness behaviours, KP activation and levels of neurotoxicity and neuroprotection in MS. In particular, there will be emphasis on how neuropsychiatric symptoms in MS occur against the shared background of inflammation and KP dysregulation. The discourse of this review aims to promote future research in elucidating KP mechanisms in MS that would inevitably lead to more targeted treatment options for neuropsychiatric symptoms and disease progression.

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Research on tryptophan metabolism and neuroinflammation on neurodegeneration in multiple sclerosis (MS) is mounting.

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This review reframes the roles of neuroinflammation and tryptophan metabolism dysregulation on mental health issues in MS.

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The impact of neuroinflammation and tryptophan metabolism on depression, suicidality, fatigue, and cognitive impairment in MS are discussed.

Influence of pregnancy and non-fasting conditions on the plasma metabolome in a rat prenatal toxicity study

The current parameters for determining maternal toxicity (e.g. clinical signs, food consumption, body weight development) lack specificity and may underestimate the extent of effects of test compounds on the dams. Previous reports have highlighted the use of plasma metabolomics for an improved and mechanism-based identification of maternal toxicity. To establish metabolite profiles of healthy pregnancies and evaluate the influence of food consumption as a confounding factor, metabolite profiling of rat plasma was performed by gas- and liquid-chromatography-tandem mass spectrometry techniques. Metabolite changes in response to pregnancy, food consumption prior to blood sampling (non-fasting) as well as the interaction of both conditions were studied. In dams, both conditions, non-fasting and pregnancy, had a marked influence on the plasma metabolome and resulted in distinct individual patterns of changed metabolites. Non-fasting was characterized by increased plasma concentrations of amino acids and diet related compounds and lower levels of ketone bodies. The metabolic profile of pregnant rats was characterized by lower amino acids and glucose levels and higher concentrations of plasma fatty acids, triglycerides and hormones, capturing the normal biochemical changes undergone during pregnancy. The establishment of metabolic profiles of pregnant non-fasted rats serves as a baseline to create metabolic fingerprints for prenatal and maternal toxicity studies.

Plasma Indoleamine-2,3-Dioxygenase (IDO) is Increased in Drug-Naï ve Major Depressed Patients and Treatment with Sertraline and Ketoprofen Normalizes IDO in Association with Pro-Inflammatory and Immune- Regulatory Cytokines

BACKGROUND

Major Depression Disorder (MDD) is accompanied by an immune response characterized by increased levels of inflammatory and immune-regulatory cytokines and stimulation of indoleamine-2,3-dioxygenase (IDO). There is also evidence that anti-inflammatory drugs may have clinical efficacy in MDD.

METHODS

This study examined a) IDO in association with interferon (IFN)-γ, Interleukin (IL)-4 and Transforming Growth Factor (TGF)-β1 in 140 drug-naïve MDD patients and 40 normal controls; and b) the effects of an eight-week treatment of sertraline with or without ketoprofen (a nonsteroidal antiinflammatory drug) on the same biomarkers in 44 MDD patients.

RESULTS

Baseline IDO, IFN-γ, TGF-β1 and IL-4 were significantly higher in MDD patients as compared with controls. Treatment with sertraline with or without ketoprofen significantly reduced the baseline levels of all biomarkers to levels which were in the normal range (IDO, TGF-β1, and IL-4) or still somewhat higher than in controls (IFN-γ). Ketoprofen add-on had a significantly greater effect on IDO as compared with placebo. The reductions in IDO, IL-4, and TGF-β1 during treatment were significantly associated with those in the BDI-II.

CONCLUSION

MDD is accompanied by activated immune-inflammatory pathways (including IDO) and the Compensatory Immune-Regulatory System (CIRS). The clinical efficacy of antidepressant treatment may be ascribed at least in part to decrements in IDO and the immune-inflammatory response. These treatments also significantly reduce the more beneficial properties of T helper-2 and T regulatory (Treg) subsets. Future research should develop immune treatments that target the immune-inflammatory response in MDD while enhancing the CIRS.

Inflammation, negative affect, and amyloid burden in Alzheimer's disease: Insights from the kynurenine pathway

BACKGROUND

Depressive symptoms in Alzheimer's disease (AD) predict worse cognitive and functional outcomes. Both AD and major depression inflammatory processes are characterized by shunted tryptophan metabolism away from serotonin (5-HT) and toward the neuroinflammatory kynurenine (Kyn) pathway. The present study assessed associations between Kyn and behavioral, neuroanatomical, neuropathological, and physiological outcomes common to both AD and negative affect across the AD continuum.

METHODS

In 58 cognitively normal, 396 mild cognitive impairment, and 112 AD participants from the Alzheimer's Disease Neuroimaging Initiative-1 (ADNI1) cohort, serum markers of 5-HT, tryptophan, and Kyn were measured and their relationships investigated with immunologic markers, affect and functional outcomes, CSF markers of beta-amyloid (Aβ) and tau, and regional gray matter.

RESULTS

A higher Kyn/Tryptophan ratio was linked to many inflammatory markers, as well as lower functional independence and memory scores. A higher Kyn/5-HT ratio showed similar associations, but also strong relationships with negative affect and neuropsychiatric disturbance, executive dysfunction, and global cognitive decline. Further, gray matter atrophy was seen in hippocampus, anterior cingulate, and prefrontal cortices, as well as greater amyloid and total tau deposition. Finally, using moderated-mediation, several pro-inflammatory factors partially mediated Kyn/5-HT and negative affect scores in participants with subclinical Aβ (i.e., Aβ-), whereas such associations were fully mediated by Complement 3 in Aβ+ participants.

CONCLUSION

These findings suggest that inflammatory signaling cascades may occur during AD, which is associated with increased Kyn metabolism that influences the pathogenesis of negative affect. Aβ and the complement system may be critical contributing factors in this process.

Pro-Inflammatory Cytokines: Potential Links between the Endocannabinoid System and the Kynurenine Pathway in Depression

Substance use/abuse is one of the main causes of depressive symptoms. Cannabis and synthetic cannabinoids in particular gained significant popularity in the past years. There is an increasing amount of clinical data associating such compounds with the inflammatory component of depression, indicated by the up-regulation of pro-inflammatory cytokines. Pro-inflammatory cytokines are also well-known to regulate the enzymes of the kynurenine pathway (KP), which is responsible for metabolizing tryptophan, a precursor in serotonin synthesis. Enhanced pro-inflammatory cytokine levels may over-activate the KP, leading to tryptophan depletion and reduced serotonin levels, which can subsequently precipitate depressive symptoms. Therefore, such mechanism might represent a possible link between the endocannabinoid system (ECS) and the KP in depression, via the inflammatory and dysregulated serotonergic component of the disorder. This review will summarize the data regarding those natural and synthetic cannabinoids that increase pro-inflammatory cytokines. Furthermore, the data on such cytokines associated with KP activation will be further reviewed accordingly. The interaction of the ECS and the KP has been postulated and demonstrated in some studies previously. This review will further contribute to this yet less explored connection and propose the KP to be the missing link between cannabinoid-induced inflammation and depressive symptoms.

Postpartum Depression: Current Status and Possible Identification Using Biomarkers

Postpartum depression (PPD) is a serious health issue that can affect about 15% of the female population within after giving birth. It often conveys significant negative consequences to the offsprings. The symptoms and risk factors are somewhat similar to those found in non-postpartum depression. The main difference resides in the fact that PPD is triggered by postpartum specific factors, including especially biological changes in the hormone levels. Patients are usually diagnosed using a questionnaire onsite or in a clinic. Treatment of PPD often involves psychotherapy and antidepressant medications. In recent years, there have been more researches on the identification of biological markers for PPD. In this review, we will focus on the current research status of PPD, with an emphasis on the recent progress made on the identification of PPD biomarkers.

Perinatal depression: Heterogeneity of disease and in animal models

Perinatal depression (PND) can have either an antepartum or postpartum onset. Although the greatest risk factor for PND is previous depression history,de novoPND occurs with the majority of cases occurring in the postpartum. Timing of depression can impact etiology, prognosis, and response to treatment. Thus, it is crucial to study the impact of the heterogeneity of PND for better health outcomes. In this review, we outline the differences between antepartum and postpartum depression onset of PND. We discuss maternal physiological changes that differ between pregnancy and postpartum and how these may differentially impact depression susceptibility. We highlight changes in the maternal steroid and peptide hormone levels, immune signalling, serotonergic tone, metabolic factors, brain morphology, and the gut microbiome. Finally, we argue that studying the heterogeneity of PND in clinical and preclinical models can lead to improved knowledge of disease etiopathology and treatment outcomes.

Prenatal IL-6 levels and activation of the tryptophan to kynurenine pathway are associated with depressive but not anxiety symptoms across the perinatal and the post-partum period in a low-risk sample

Depression and anxiety symptoms are highly prevalent among women during pregnancy and post-partum. Previous studies suggest that one of the pathophysiological underpinnings could be an enhanced metabolism of tryptophan (Trp) into kynurenine (Kyn) due to increased inflammation. However, the longitudinal changes in the Kyn pathway and the complex interplay with inflammation and stress in women with perinatal depressive or anxiety symptoms are incompletely understood. We examined a cohort of healthy women at 34-36 gestational weeks. One hundred and ten women were assessed for salivary cortisol and 97 participants were also assessed for serum levels of Trp, Kyn and Interleukin 6 (IL-6). Women filled in two screening questionnaires for depressive (Edinburgh Postnatal Depression Scale (EPDS)) and anxiety (State Trait Anxiety Inventory subscale (STAI-S)) symptoms at 34-36 gestational weeks, delivery, 3 and 12 months postpartum. Unexpectedly, lower prenatal Kyn levels were associated with higher depressive symptoms in late pregnancy. Furthermore, prenatal Trp levels and the Kyn/Trp ratio moderate the association between IL-6 levels and depressive symptoms during the perinatal and the post-partum period. We found no interactions between Trp and Kyn biomarkers and cortisol on depressive symptoms. The observed associations were more robustly found for depressive symptoms, whereas weak and non-significant effects were found for the trajectory of anxiety symptoms. Overall, our data support the involvement of the Trp to Kyn pathway and inflammation in the course of depressive but not anxiety symptoms in women from late pregnancy until one-year post-partum, providing new evidence on the mechanisms regulating emotions during pregnancy and after delivery in a low-risk sample.

Low Neuroactive Steroids Identifies a Biological Subtype of Depression in Adults with Human Immunodeficiency Virus on Suppressive Antiretroviral Therapy

Background

The prevalence and mortality risk of depression in people with human immunodeficiency virus (HIV) infection receiving antiretroviral therapy (ART) is higher than in the general population, yet biomarkers for therapeutic targeting are unknown. In the current study, we aimed to identify plasma metabolites associated with depressive symptoms in people with HIV receiving ART.

Methods

This is a prospective study of ART-treated HIV-infected adults with or without depressive symptoms assessed using longitudinal Beck Depression Inventory scores. Plasma metabolite profiling was performed in 2 independent cohorts (total n = 99) using liquid and gas chromatography and tandem mass spectrometry.

Results

Participants with depressive symptoms had lower neuroactive steroids (dehydroepiandrosterone sulfate [DHEA-S], androstenediols, and pregnenolone sulfate) compared with those without depressive symptoms. The cortisol/DHEA-S ratio, an indicator of hypothalamic-pituitary-adrenal axis imbalance, was associated with depressive symptoms (P < .01) because of low DHEA-S levels, whereas cortisol was similar between groups. The odds of having depressive symptoms increased with higher cortisol/DHEA-S ratios (adjusted odds ratio, 2.5 per 1-unit increase in z score; 95% confidence interval, 1.3–4.7), independent of age and sex. The kynurenine-to-tryptophan ratio showed no significant associations.

Conclusions

These findings suggest that altered neuroactive steroid metabolism may contribute to the pathophysiological mechanisms of depression in ART-treated HIV-infected adults, representing a potential biological pathway for therapeutic targeting.

Homeostasis Imbalance of Microglia and Astrocytes Leads to Alteration in the Metabolites of the Kynurenine Pathway in LPS-Induced Depressive-Like Mice

In the pathology-oriented study of depression, inflammation hypothesis has received increasing attention for recent years. To mimic the depressive state caused by inflammation, rodents injected intraperitoneally with lipopolysaccharide (LPS) are usually used to stimulate an immune response. However, the dose of LPS that causes depressive-like behavior varies widely across many literatures. Previous study has uncovered the non-linearity in the dose-effect relationship for the depressive-like behavior induced by LPS administration, while the reason for this is still unclear. The present study aims to investigate the underlying mechanisms of this non-linear dose-dependent relationship. Four groups of mice were injected intraperitoneally with different doses of LPS (0, 0.32, 0.8, and 2 mg/kg). The tail suspension test was conducted to evaluate the depressive-like behavior within 23-25 h after the LPS administration. The neuroplasticity was assessed by the levels of related proteins, TrkB and PSD-95, and by the quantification of neurons using Nissl staining. The levels of the two metabolites of the kynurenine (KYN) pathway, 3-hydroxykynurenine (3-HK) and kynurenic acid (KYNA), in the brain were analyzed by LC-MS/MS. Activation of microglia and astrocytes in the brain were also determined by immunohistochemistry and western blotting, respectively. The results showed that, compared with the control group, the mice in the 0.8 mg/kg LPS-treated group exhibited a remarkable increase of immobility time in the tail suspension test. The neuroplasticity of mice in the 0.8 mg/kg LPS-treated group was also significantly reduced. The neurotoxic metabolite, 3-HK, was accumulated significantly in the hippocampus of the 0.8 mg/kg LPS-treated mice. Surprisingly, the 2 mg/kg LPS-treated mice did not exhibit a remarkable change of 3-HK but expressed increased KYNA significantly, which is neuroprotective. Furthermore, the activation of microglia and astrocytes, which were recognized as the primary source of 3-HK and KYNA, respectively, corresponded to the content of these two metabolites of the KYN pathway in each group. Consequently, it was speculated that the homeostasis of different glial cells could lead to a non-linear dose-dependent behavior by regulating the KYN pathway in the LPS-induced depressive-like mice.

Antidepressive Mechanisms of Probiotics and Their Therapeutic Potential

The accumulating knowledge of the host-microbiota interplay gives rise to the microbiota-gut-brain (MGB) axis. The MGB axis depicts the interkingdom communication between the gut microbiota and the brain. This communication process involves the endocrine, immune and neurotransmitters systems. Dysfunction of these systems, along with the presence of gut dysbiosis, have been detected among clinically depressed patients. This implicates the involvement of a maladaptive MGB axis in the pathophysiology of depression. Depression refers to symptoms that characterize major depressive disorder (MDD), a mood disorder with a disease burden that rivals that of heart diseases. The use of probiotics to treat depression has gained attention in recent years, as evidenced by increasing numbers of animal and human studies that have supported the antidepressive efficacy of probiotics. Physiological changes observed in these studies allow for the elucidation of probiotics antidepressive mechanisms, which ultimately aim to restore proper functioning of the MGB axis. However, the understanding of mechanisms does not yet complete the endeavor in applying probiotics to treat MDD. Other challenges remain which include the heterogeneous nature of both the gut microbiota composition and depressive symptoms in the clinical setting. Nevertheless, probiotics offer some advantages over standard pharmaceutical antidepressants, in terms of residual symptoms, side effects and stigma involved. This review outlines antidepressive mechanisms of probiotics based on the currently available literature and discusses therapeutic potentials of probiotics for depression.

Neurobiology of maternal mental illness

This chapter provides an overview of current research discoveries beginning to uncover the neurobiology of maternal mental illness. Results are described according to standard diagnostic categories (specifically, perinatal depression, perinatal anxiety and OCD, postpartum psychosis and bipolar disorder, and trauma and posttraumatic stress disorder), yet we aim to put this approach in context with the introduction of a classification model for psychiatric research, the research domain criteria, gaining traction in basic and clinical translational fields. We first review a new area of study, the neuroplasticity of the pregnant and postpartum brain, as work here has relevance for understanding the pathophysiology of mental disorders and may provide clues to changes in brain functioning that are related to compromised parenting in the context of postpartum depression. We next provide background information on neuroendocrine and immune changes during pregnancy and, to a lesser extent, the postpartum period, as alterations in these systems are significantly implicated in underlying neurobiology of mental illness for peripartum women. Our discussion of the major mental illnesses for pregnant and postpartum women includes neuroendocrine changes, neuroinflammation, and neurotransmitter alterations, as well as circuit dysfunction. Overall, remarkable progress has been made in identifying variations in neurobiology (and related systems) involved in maternal mental illness; yet, it is clear that, as classified with standard diagnostic systems, these are heterogeneous disorders and there is individual variability in the alterations in neurobiology for the same illness.

Vitamin D supplementation ameliorates severity of generalized anxiety disorder (GAD)

This study investigated the effects of vitamin D supplementation on Generalized Anxiety Disorder (GAD) clinical symptoms and neurochemical biomarkers including serotonin, neopterin and kynurenine. Thirty male and female patients diagnosed with GAD and had vitamin D deficiency were recruited from the psychiatric clinic at King Abdulaziz University Hospital and divided into two groups; one group of patients (n = 15) received standard of care (SOC) plus 50,000 IU vitamin D (once/week) for 3 months, while the other group (n = 15) received SOC alone. Biochemical parameters including serum vitamin D, serotonin, neopterin and kynurenine were measured for all patients enrolled in the trial. In addition, the Generalized Anxiety Disorder 7-item (GAD-7) scale was used to measure the severity of GAD symptoms in both vitamin D treated- and untreated-patients. Significant improvements in GAD scores were observed in the vitamin D-treated group compared to the group that did not receive vitamin D. In addition, serum serotonin concentrations were significantly increased while serum neopterin were significantly decreased in vitamin D-treated vs. untreated patients. In contrast, no significant differences were found in serum kynurenine concentrations at the end of the study period between the two groups. No changes either in GAD-7 scores or in any of the biochemical measurements were observed in the group that received only SOC after 3 months. Vitamin D supplementation was effective in ameliorating the severity of GAD symptoms by increasing serotonin concentrations and decreasing the levels of the inflammatory biomarker neopterin in GAD patients.

Tryptophan in health and disease

Tryptophan (TRP), an essential amino acid in mammals, is involved in several physiological processes including neuronal function, immunity, and gut homeostasis. In humans, TRP is metabolized via the kynurenine and serotonin pathways, leading to the generation of biologically active compounds, such as serotonin, melatonin and niacin. In addition to endogenous TRP metabolism, resident gut microbiota also contributes to the production of specific TRP metabolites and indirectly influences host physiology. The variety of physiologic functions regulated by TRP reflects the complex pattern of diseases associated with altered homeostasis. Indeed, an imbalance in the synthesis of TRP metabolites has been associated with pathophysiologic mechanisms occurring in neurologic and psychiatric disorders, in chronic immune activation and in the immune escape of cancer. In this chapter, the role of TRP metabolism in health and disease is presented. Disorders involving the central nervous system, malignancy, inflammatory bowel and cardiovascular disease are discussed.

Changes in tryptophan metabolism during pregnancy and postpartum periods: Potential involvement in postpartum depressive symptoms

BACKGROUND

Many women experience depressive symptoms during pregnancy and postpartum periods. These depressive symptoms are often accompanied by other inflammatory morbidities present during pregnancy. Tryptophan (TRP) metabolism has attracted considerable attention due to its influence on the onset of depression via induction of inflammation. We examined the changes in plasma levels of TRP metabolites in pregnant women with depressive symptoms during pregnancy and/or the postpartum period.

METHODS

In line with a previous analysis using the Edinburgh Postnatal Depression Scale (EPDS), participants were divided into a non-depressive (ND) group, a postpartum depressive (PD) group, a temporary gestational depressive (TG) group, and a continuous depressive (CD) group. Blood samples were collected before and 1 month after delivery. The concentrations of plasma TRP metabolites were measured using high-performance liquid chromatography (HPLC).

RESULTS

There are differences in plasma levels of TRP metabolites during pregnancy and postpartum periods between the ND group and the PD group, but not the TG or CD group. In the PD group, plasma levels of kynurenine (KYN) and kynurenic acid (KA), and KYN/TRP and KA/KYN ratio during the pregnancy period were higher and 3-hydroxyanthranilic acid (3HAA) during the postpartum period was lower than those in the ND group.

LIMITATIONS

Histories regarding mood disorders before pregnancy were not assessed.

CONCLUSIONS

The higher plasma levels of KYN and KA, and KYN/TRP and KA/KYN ratio during pregnancy period and lower plasma level of 3HAA during the postpartum period could be useful predictive and diagnostic markers of postpartum depressive symptoms.

Serotonin and motherhood: From molecules to mood

Emerging research points to a valuable role of the monoamine neurotransmitter, serotonin, in the display of maternal behaviors and reproduction-associated plasticity in the maternal brain. Serotonin is also implicated in the pathophysiology of numerous affective disorders and likely plays an important role in the pathophysiology of maternal mental illness. Therefore, the main goals of this review are to detail: (1) how the serotonin system of the female brain changes across pregnancy and postpartum; (2) the role of the central serotonergic system in maternal caregiving and maternal aggression; and (3) how the serotonin system and selective serotonin reuptake inhibitor medications (SSRIs) are involved in the treatment of maternal mental illness. Although there is much work to be done, studying the central serotonin system's multifaceted role in the maternal brain is vital to our understanding of the processes governing matrescence and the maintenance of motherhood.

The dynamic serotonin system of the maternal brain

Many pregnant and postpartum women worldwide suffer from high anxiety and/or depression, which can have detrimental effects on maternal and infant well-being. The first-line pharmacotherapies for prepartum and postpartum affective disorders continue to be the selective serotonin reuptake inhibitors (SSRIs), despite the lack of large well-controlled studies demonstrating their efficacy in reproducing women and the potential for fetal/neonatal exposure to the drugs. Prepartum or postpartum use of SSRIs or other drugs that modulate the brain's serotonin system is also troubling because very little is known about the typical, let alone the atypical, changes that occur in the female central serotonin system across reproduction. We do know from a handful of studies of women and female laboratory rodents that numerous aspects of the central serotonin system are naturally dynamic across reproduction and are also affected by pregnancy stress (a major predisposing factor for maternal psychopathology). Thus, it should not be assumed that the maternal central serotonin system being targeted by SSRIs is identical to non-parous females or males. More information about the normative and stress-derailed changes in the maternal central serotonin system is essential for understanding how serotonin is involved in the etiology of, and the best use of SSRIs for potentially treating, affective disorders in the pregnant and postpartum populations.

Plasma and cerebrospinal fluid inflammatory cytokines in perinatal depression

BACKGROUND

While perinatal depression is one of the most common complications of pregnancy, there is an insufficient understanding of the mechanistic underpinnings of disease. While an association between peripheral inflammatory cytokines and major depressive disorder has been demonstrated, cytokines cannot freely cross the blood-brain barrier, and thus, they give little insight into alternations in brain function. Because the brain is in direct communication with the cerebrospinal fluid, assessment of inflammation in the cerebrospinal fluid may be more directly related to the biologic markers of affective change.

OBJECTIVE

Our objectives were to examine the association between perinatal depression and inflammatory cytokines in plasma, the association between perinatal depression and inflammatory cytokines in cerebrospinal fluid, and the correlations between plasma and cerebrospinal fluid inflammatory cytokines.

STUDY DESIGN

This was a prospective, observational study of women with a singleton gestation at term undergoing a scheduled cesarean delivery. Women were screened for depression and those with depressive symptomatology preferentially enrolled. The Mini-International Neuropsychiatric Interview was administered to confirm the clinical diagnosis of depression. Maternal plasma and cerebrospinal fluid were collected preoperatively and cytokines measured via flow cytometry. Bivariable and multivariable analyses were used to determine the association between each cytokine and perinatal depression. Correlations were measured between the cytokines in plasma and cerebrospinal fluid.

RESULTS

Of the 117 women who met inclusion criteria, 76 (65%) screened positive for depression, 15 (20%) of whom met the clinical diagnostic criteria for depression. There were no significant associations between any of the plasma cytokines and perinatal depression in our sample. Conversely, in multivariable analyses, higher cerebrospinal fluid interleukin-1β (adjusted odds ratio, 232.7, 95% confidence interval, 5.9-9148.5), interleukin-23 (adjusted odds ratio, 22.1, 95% confidence interval, 1.7-294.5), and interleukin-33 (adjusted odds ratio, 1.7, 95% confidence interval, 1.1-2.6) concentrations were significantly associated with increased odds of perinatal depression. The plasma and cerebrospinal fluid cytokine concentrations were not strongly correlated.

CONCLUSION

Higher concentrations of cerebrospinal fluid cytokines were associated with perinatal depression. These cerebrospinal fluid cytokines were not strongly correlated with plasma cytokines, and accordingly, plasma cytokines were not significantly associated with perinatal depression. Central neuroinflammation, as opposed to peripheral inflammation, may represent a mechanistic pathway that contributes to perinatal depression.

Tuberculosis - Depression syndemic: A public health challenge

INTRODUCTION

Depression is common in Tuberculosis (TB) and associated with adverse outcomes through pathogenic mechanisms and impaired self-care behaviours including reduced treatment adherence. Undiagnosed depression can threaten the robustness of DOTS model despite large public health investment. The Depression-Tuberculosis Syndemic requires collaborative partnership with mental health professionals.

AIM

To study the evidence base for Depression-Tuberculosis Syndemic.

METHODOLOGY

A Pubmed and Google Scholar search was conducted using the key words "Depression", "Tuberculosis" and "Syndemic" and abstracts screened for appropriateness and relevance.

RESULT

Depression-TB Syndemic is common with a bidirectional relationship. Depression is associated with higher hazard ratio and increased prevalence of TB. Depression is independently associated with higher morbidity, mortality, drug resistance, risk of TB reactivation and community TB transmission. The underlying biopsychosocial mechanism of Depression- Tuberculosis Syndemic includes biological factors like inflammatory cascade, HPA axis dysregulation and psychosocial factors like perceived stigma and treatment non-adherence.

DISCUSSION

Depression is a poor prognostic factor in TB. The National Mental Health Programme (NMHP) and National Strategic Plan (NSP) for Tuberculosis Elimination (2017-2025) work in independent verticals with no integration at policy or at ground level. This results in lack of identification and appropriate management of depression in patients with Tuberculosis despite repeated contact with health care personnel in DOTS centres. A collaborative approach for early diagnosis and management of depression in patients with Tuberculosis (Secondary Prevention) can help decrease the burden of disease and improve outcomes.

CONCLUSION

Depression-TB Syndemic requires collaborative approaches at the program level and at the point of service delivery.

The association of serum C-reactive protein with the occurrence and course of postpartum depression

CRP has been positively correlated with depressive symptomatology but this has received less study in postpartum depression (PPD). In this secondary analysis of a trial of PPD treatment, depressive symptoms (Structured Interview Guide for the Hamilton Depression Rating Scale-Atypical Depression Symptoms (SIGH-ADS₂₉)) and serum CRP levels were assessed and associations between CRP and SIGH-ADS₂₉ scores evaluated. The associations between baseline log CRP and depression response and remission were also assessed. Of the 35 women included, neither baseline log CRP nor exit log CRP was significantly associated with SIGH-ADS₂₉ score. Baseline CRP was not associated with response or remission. In this sample of women with PPD, CRP was not associated with depressive symptoms nor response to treatment.

Pathophysiological mechanisms implicated in postpartum depression

This review aims to summarize the diverse proposed pathophysiological mechanisms contributing to postpartum depression, highlighting both clinical and basic science research findings. The risk factors for developing postpartum depression are discussed, which may provide insight into potential neurobiological underpinnings. The evidence supporting a role for neuroendocrine changes, neuroinflammation, neurotransmitter alterations, circuit dysfunction, and the involvement of genetics and epigenetics in the pathophysiology of postpartum depression are discussed. This review integrates clinical and preclinical findings and highlights the diversity in the patient population, in which numerous pathophysiological changes may contribute to this disorder. Finally, we attempt to integrate these findings to understand how diverse neurobiological changes may contribute to a common pathological phenotype. This review is meant to serve as a comprehensive resource reviewing the proposed pathophysiological mechanisms underlying postpartum depression.

Antidepressant effects of direct-acting antivirals against hepatitis C virus-Results from a pilot study

BACKGROUND AND AIMS

The new direct-acting antiviral agents (DAA) have revolutionized the treatment of patients with chronic hepatitis C virus (HCV) infection. This study investigates to which extent DAA affect fatigue and mood and, if so, whether this results from changes to tryptophan (TRP) metabolism, as reflected by two critical biosynthetic pathways, serotonin (SRT) generation from TRP and TRP degradation through kynurenines (KYN) via indoleamine 2,3-dioxygenase (IDO).

METHODS

This study assessed 24 patients with chronic HCV infection, before (T1), during (T2: at 4 weeks) and 12 weeks post-treatment with DAA (T3) with respect to viral load, fatigue and depressive symptoms (BDI-II questionnaire), physical activity (actigraph) and plasma serotonin-tryptophan metabolites (LC/MS). The KYN:TRP ratio reflected IDO activity.

RESULTS

All participants achieved sustained virological response (SVR12) with DAA treatment (79% sofosbuvir-based). Fatigue (scores at T1:0.83 ± 0.70, T2:0.48 ± 0.70, T3:0.30 ± 0.50; P = 0.023) and depressive symptoms (scores at T1:9.8 ± 10.2, T2:6.0 ± 7.3, T3:5.0 ± 7.6; P = 0.005) improved significantly on therapy, whereas no changes were noted in five untreated controls. TRP plasma concentrations markedly decreased (T1:306 ± 179 mg/L, T2:283 ± 84 mg/L), whereas 5-HTP levels increased (T1:0.08 ± 0.01 mg/L, T2:0.10 ± 0.06 mg/L). KYN concentrations (T1:2.4 ± 2.0 mg/L, T2:3.7 ± 1.4 mg/L, P = 0.003) increased significantly during treatment, as did IDO activity (T1:0.008 ± 0.006 mg/L, T2:0.014 ± 0.004 mg/L; P < 0.001).

CONCLUSIONS

In this study, DAA exert positive and persistent effects on both fatigue and mood in patients with chronic HCV infection. These extrahepatic benefits are, at least in part, related to the modulation of TRP metabolism. The robust elevation of KYN concentrations challenges the current paradigm of low KYN levels as prerequisite for mental health.