Sex differences in the neuro-immune consequences of stress: Focus on depression and anxiety

The relationship between plasma interleukin-6 and cognition based on curve correlation in drug-naïve patients with major depressive disorder

BACKGROUND

The effect of interleukin-6 (IL-6) on cognition in patients with major depressive disorder (MDD) remains unclear. The aim of the present study was to investigate for the first time the non-linear relationship between plasma IL-6 and cognition and its sex-specific associations in patients with drug-naïve MDD.

METHODS

A total of 326 participants, including 237 drug-naïve MDD patients and 89 healthy controls (HCs), were included in this study. All participants completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and fasting venous blood was collected for IL-6 measurement. Patients with MDD completed the Hamilton Depression Scale-17 (HAMD-17) and the Hamilton Anxiety Scale-14 (HAMA-14) assessments. Two-way analysis of variance and curve estimation analyses were used to explore the effects of IL-6 on cognition and its sex differences.

RESULTS

We found that IL-6 and cognition were associated in different patterns in HCs and MDD patients. The best model for curve estimation between IL-6 and attention (F = 2.736, p = 0.045) and HAMA (F = 6.416, p < 0.001) in females with MDD was the cubic model. In male MDD patients, the best model for curve estimation between IL-6 and immediate memory was the cubic model (F = 3.077, p = 0.034). However, in HCs, the best model for curve estimation analysis between IL-6 and language was the quadratic model (F = 3.803, p = 0.026).

LIMITATIONS

The main limitations were cross-sectional design.

CONCLUSION

There was a non-linear and sex-specific relationship between IL-6 levels and cognition in patients with MDD.

Is there something sexual in the ventral midline thalamus?

This mini-review explores sexual dimorphism in the ventral midline thalamus, focusing on the reuniens nucleus and its role in behavioral functions. Traditionally linked to tasks such as working memory, cognitive flexibility, fear generalization, and memory consolidation, most studies have been conducted in male rodents. Research comparing the effects of ventral midline thalamus manipulations between female and male rodents is limited. Emerging evidence suggests sex-specific differences, particularly in response to stress, pharmacological manipulations, and memory processes. Studies reveal distinct c-Fos expression patterns in the reuniens nucleus between females and males, especially under stress, with females often showing different neural activation. Additionally, females exhibit different recruitment of the reuniens nucleus in object recognition tasks, indicating possible sex-dependent cognitive strategies. While evidence suggests functional differences between sexes in the reuniens nucleus, current data are limited. Further research is needed to understand how sex influences brain function and cognition, particularly in the ventral midline thalamus, which is crucial for various cognitive processes.

Alcohol drinking is attenuated by PDE4 inhibition but partial microglia depletion is not sufficient to block stress-induced escalation of alcohol intake in female mice

Stress is a major contributing factor to binge drinking and development of alcohol use disorders (AUD), particularly in women. Both stress and chronic ethanol can enhance neuroinflammatory processes, which may dysregulate limbic circuits involved in ethanol reinforcement. Clinical and preclinical studies have identified sex differences in alcohol intake in response to neuroinflammatory triggers. Since both cyclic AMP (cAMP) signaling and microglial activation contribute to neuroinflammation, we explored their contribution to stress-induced ethanol drinking in mice. To this end, we first trained C57BL/6J male and female mice to volitionally drink ethanol through a modified version of the "Drinking-in-the-Dark" paradigm. We then assessed whether exposure to foot shock stress followed by repeated exposure to the previously stress-paired context might alter volitional ethanol drinking. We observed that stress exposure resulted in a delayed increase in ethanol intake, but only in female mice. The anti-inflammatory drug Apremilast, an inhibitor of phosphodiesterase type 4 (PDE4; the primary enzyme for cAMP degradation in the brain), reduced ethanol intake and decreased preference for ethanol regardless of stress exposure in females. In contrast, a partial pharmacological depletion of microglia via PLX3397 treatment did not alter baseline ethanol drinking or stress-induced ethanol drinking significantly in female mice. This study shows that female mice are more susceptible to stress-induced ethanol drinking than males, and that this occurs even after partial microglial depletion. In addition, modulation of cAMP signaling by Apremilast administration reduced ethanol drinking regardless of stress exposure, supporting the idea that it might be useful for treatment of AUD.

Applying the Research Domain Criteria to Rodent Studies of Sex Differences in Chronic Stress Susceptibility

Women have a 2-fold increased rate of stress-associated psychiatric disorders such as depression and anxiety, but the mechanisms that underlie this increased susceptibility remain incompletely understood. Historically, female subjects were excluded from preclinical studies and clinical trials. Additionally, chronic stress paradigms used to study psychiatric pathology in animal models were developed for use in males. However, recent changes in National Institutes of Health policy encourage inclusion of female subjects, and considerable work has been performed in recent years to understand biological sex differences that may underlie differences in susceptibility to chronic stress-associated psychiatric conditions. Here, we review the utility as well as current challenges of using the framework of the National Institute of Mental Health's Research Domain Criteria as a transdiagnostic approach to study sex differences in rodent models of chronic stress including recent progress in the study of sex differences in the neurobehavioral domains of negative valence, positive valence, cognition, social processes, and arousal.

Anxiety-Like Behaviors in Mice Unmasked: Revealing Sex Differences in Anxiety Using a Novel Light-Heat Conflict Test

Anxiety and chronic pain afflict hundreds of millions worldwide. Anxiety and pain are more prevalent in females compared to males. Unfortunately, robust sex differences in human anxiety are not recapitulated in rodent tests, and results from rodent pain studies frequently fail to translate clinically. Therefore, there is a need to develop tests that reflect the differential salience of anxiety or pain-related stimuli between the sexes. Accordingly, here we introduce the Thermal Increments Dark-Light (TIDAL) conflict test. The TIDAL test places an anxiety-relevant stimulus (dark vs. illuminated chamber) in conflict with a heat-related stimulus (incrementally heated vs. isothermic chamber); mice freely explore both apparatus chambers. Here, we aim to determine whether the TIDAL conflict test reveals in mice underappreciated sex differences in anxiety and/or heat sensitivity. We establish in four distinct experiments that females on the TIDAL conflict test persist substantially longer on the dark-heated plate, suggesting that female mice exhibit elevated anxiety-like behavior. Mice more strongly prefer the heated-dark plate on the TIDAL conflict test compared to control thermal place preference with both chambers illuminated. We also reveal that an anxiety-relieving drug, paroxetine, reduces mouse preference for the heating dark plate, supporting the validity of the TIDAL test. Therefore, our new TIDAL conflict test reliably unmasks the relative salience of anxiety (vs. heat sensitivity): mice that are female exhibit robust anxiety-like behaviors not consistently observed in classical tests. Future studies should incorporate TIDAL and other conflict tests to better understand rodent behavior and to identify mechanisms underlying anxiety and pain.

Pooled and global burdens and trends of five common cancers attributable to diet in 204 countries and territories from 1990 to 2019: an analysis of the Global Burden of Disease Study

OBJECTIVE

Increasing evidence has shown that dietary behaviors are closely correlated with the carcinogenesis and progression of many types of cancer. However, few studies have assessed the global diet-related burden of cancer. This study aimed to estimate the pooled burdens and trends of five types of cancers attributable to dietary behaviors.

METHODS

Data regarding cancer attributable to dietary behaviors were extracted from the Global Burden of Disease study 2019, including the death cases and age-standardized death rates, and disability-adjusted life years (DALYs) estimated according to diseases, age, sex, the socio-demographic index (SDI) and location.

RESULTS

According to the Global Burden of Disease study 2019, five types of cancer were affected by dietary behaviors: colon and rectum cancer; tracheal, bronchus and lung cancer; stomach cancer; esophageal cancer and breast cancer. Unhealthy dietary behaviors for cancer caused a total of 605.4 thousand deaths and 13951.3 thousand DALYs globally. The burden of cancer attributable to dietary risks was higher for men than for women. The highest age-standardized death rates in 2019 were observed in southern Latin America, and the lowest rates were observed in North Africa and the Middle East. The greatest increases in the age-standardized death rates, from 1990 to 2019, were found in Western Sub-Saharan Africa, with the greatest decreases in Central Asia. The highest attributable proportions of death or DALYs were colon and rectum cancer. The greatest diet-related cancer burden was observed in regions with a high-middle SDI.

CONCLUSION

Global age-standardized deaths and DALYs rates attributable to diet-related cancer are considerable and cause a substantial burden. Successful population-wide initiatives targeting unhealthy dietary behaviors would reduce this burden.

Connecting the dots: sex, depression, and musculoskeletal health

Depression and multiple musculoskeletal disorders are overrepresented in women compared with men. Given that depression is a modifiable risk factor and improvement of depressive symptoms increases positive outcomes following orthopedic intervention, efforts to improve clinical recognition of depressive symptoms and increased action toward ameliorating depressive symptoms among orthopedic patients are positioned to reduce complications and positively affect patient-reported outcomes. Although psychosocial factors play a role in the manifestation and remittance of depression, it is also well appreciated that primary biochemical changes are capable of causing and perpetuating depression. Unique insight for novel treatments of depression may be facilitated by query of the bidirectional relationship between musculoskeletal health and depression. This Review aims to synthesize the diverse literature on sex, depression, and orthopedics and emphasize the potential for common underlying biological substrates. Given the overrepresentation of depression and musculoskeletal disorders among women, increased emphasis on the biological drivers of the co-occurrence of these disorders is positioned to improve women's health.

The functional role of locus coeruleus microglia in the female stress response

Neuropsychiatric disorders that result from stress exposure are highly associated with central inflammation. Our previous work established that females selectively exhibit heightened proinflammatory cytokine production within the noradrenergic locus coeruleus (LC) along with a hypervigilant behavioral phenotype in response to witnessing social stress, and ablation of microglia using pharmacological techniques prevents this behavioral response. These studies were designed to further investigate the impact of stress-induced neuroimmune signaling on the long-term behavioral and neuronal consequences of social stress exposure in females using chemogenetics. We first characterized the use of an AAV-CD68-Gi-DREADD virus targeted to microglia within the LC and confirmed viral transduction, selectivity, and efficacy. Clozapine-n-oxide (CNO) was used for the suppression of microglial reactivity during acute and chronic exposure to vicarious/witness social defeat in female rats. Chemogenetic-mediated inhibition of microglial reactivity during stress blunted the neuroimmune response to stress and prevented both acute and long-term hypervigilant behavioral responses. Further, a history of microglial suppression during stress prevented the heightened LC activity typically observed in response to stress cues. These studies are among the first to use a chemogenetic approach to inhibit microglia within the female brain in vivo and establish LC inflammation as a key mechanism underlying the behavioral and neuronal responses to social stress in females.

Gender-related alterations of serum trace elements and neurometabolism in the anterior cingulate cortex of patients with major depressive disorder

BACKGROUND

It is widely known that sex differences have a significant impact on patients with major depressive disorder (MDD). This study aims to evaluate the sex-related connection between serum trace elements and changes in neurometabolism in the anterior cingulate cortex (ACC) of MDD patients.

METHODS

109 untreated MDD patients and 59 healthy controls underwent proton magnetic resonance spectroscopy (1H-MRS) under resting conditions. We measured metabolic ratios in the ACC from both sides. Additionally, venous blood samples were taken from all participants to detect calcium (Ca), phosphorus, magnesium (Mg), copper (Cu), ceruloplasmin (CER), zinc (Zn), and iron (Fe) levels. We performed association and interaction analyses to explore the connections between the disease and gender.

RESULTS

In individuals with MDD, the Cu/Zn ratio increased, while the levels of Mg, CER, Zn and Fe decreased. Male MDD patients had lower Cu levels, while female patients had an increased Cu/Zn ratio. We observed significant gender differences in Cu, CER and the Cu/Zn ratio in MDD. Male patients showed a reduced N-acetyl aspartate (NAA)/phosphocreatine + creatine (PCr + Cr) ratio in the left ACC. The NAA/PCr + Cr ratio decreased in the right ACC in patients with MDD. In the left ACC of male MDD patients, the Cu/Zn ratio was inversely related to the NAA/PCr + Cr ratio, and Fe levels were negatively associated with the GPC + PC/PCr + Cr ratio.

CONCLUSIONS

Our findings highlight gender-specific changes in Cu homeostasis among male MDD patients. The Cu/Zn ratio and Fe levels in male MDD patients were significantly linked to neurometabolic alterations in the ACC.

Microglial responses to inflammatory challenge in adult rats altered by developmental exposure to polychlorinated biphenyls in a sex-specific manner

Polychlorinated biphenyls are ubiquitous environmental contaminants linkedc with peripheral immune and neural dysfunction. Neuroimmune signaling is critical to brain development and later health; however, effects of PCBs on neuroimmune processes are largely undescribed. This study extends our previous work in neonatal or adolescent rats by investigating longer-term effects of perinatal PCB exposure on later neuroimmune responses to an inflammatory challenge in adulthood. Male and female Sprague-Dawley rats were exposed to a low-dose, environmentally relevant, mixture of PCBs (Aroclors 1242, 1248, and 1254, 1:1:1, 20 μg / kg dam BW per gestational day) or oil control during gestation and via lactation. Upon reaching adulthood, rats were given a mild inflammatory challenge with lipopolysaccharide (LPS, 50 μg / kg BW, ip) or saline control and then euthanized 3 hours later for gene expression analysis or 24 hours later for immunohistochemical labeling of Iba1+ microglia. PCB exposure did not alter gene expression or microglial morphology independently, but instead interacted with the LPS challenge in brain region- and sex-specific ways. In the female hypothalamus, PCB exposure blunted LPS responses of neuroimmune and neuromodulatory genes without changing microglial morphology. In the female prefrontal cortex, PCBs shifted Iba1+ cells from reactive to hyperramified morphology in response to LPS. Conversely, in the male hypothalamus, PCBs shifted cell phenotypes from hyperramified to reactive morphologies in response to LPS. The results highlight the potential for long-lasting effects of environmental contaminants that are differentially revealed over a lifetime, sometimes only after a secondary challenge. These neuroimmune endpoints are possible mechanisms for PCB effects on a range of neural dysfunction in adulthood, including mental health and neurodegenerative disorders. The findings suggest possible interactions with other environmental challenges that also influence neuroimmune systems.

Post-weaning social isolation alters sociability in a sex-specific manner

Adolescence is a critical period for brain development in humans and stress exposure during this time can have lasting effects on behavior and brain development. Social isolation and loneliness are particularly salient stressors that lead to detrimental mental health outcomes particularly in females, although most of the preclinical work on social isolation has been done in male animals. Our lab has developed a model of post-weaning adolescent social isolation that leads to increased drug reward sensitivity and altered neuronal structure in limbic brain regions. The current study utilized this model to determine the impact of adolescent social isolation on a three-chamber social interaction task both during adolescence and adulthood. We found that while post-weaning isolation does not alter social interaction during adolescence (PND45), it has sex-specific effects on social interaction in young adulthood (PND60), potentiating social interaction in male mice and decreasing it in female mice. As early life stress can activate microglia leading to alterations in neuronal pruning, we next examined the impact of inhibiting microglial activation with daily minocycline administration during the first 3 weeks of social isolation on these changes in social interaction. During adolescence, minocycline dampened social interaction in male mice, while having no effect in females. In contrast, during young adulthood, minocycline did not alter the impact of adolescent social isolation in males, with socially isolated males exhibiting higher levels of social interaction compared to their group housed counterparts. In females, adolescent minocycline treatment reversed the effect of social isolation leading to increased social interaction in the social isolation group, mimicking what is seen in naïve males. Taken together, adolescent social isolation leads to sex-specific effects on social interaction in young adulthood and adolescent minocycline treatment alters the effects of social isolation in females, but not males.

Post-weaning social isolation alters sociability in a sex-specific manner

Adolescence is a critical period for brain development in humans and stress exposure during this time can have lasting effects on behavior and brain development. Social isolation and loneliness are particularly salient stressors that lead to detrimental mental health outcomes particularly in females, although most of the preclinical work on social isolation has been done in male animals. Our lab has developed a model of post-weaning adolescent social isolation that leads to increased drug reward sensitivity and altered neuronal structure in limbic brain regions. The current study utilized this model to determine the impact of adolescent social isolation on a three-chamber social interaction task both during adolescence and adulthood. We found that while post-weaning isolation does not alter social interaction during adolescence (PND45), it has sex-specific effects on social interaction in adulthood (PND60), potentiating social interaction in male mice and decreasing it in female mice. As early life stress can activate microglia leading to alterations in neuronal pruning, we next examined the impact of inhibiting microglial activation with daily minocycline administration during the first three weeks of social isolation on these changes in social interaction. During adolescence, minocycline dampened social interaction in male mice, while having no effect in females. In contrast, during adulthood, minocycline did not alter the impact of adolescent social isolation in males, with socially isolated males exhibiting higher levels of social interaction compared to their group housed counterparts. In females, adolescent minocycline treatment reversed the effect of social isolation leading to increased social interaction in the social isolation group, mimicking what is seen in naïve males. Taken together, adolescent social isolation leads to sex-specific effects on social interaction in adulthood and adolescent minocycline treatment alters the effects of social isolation in females, but not males.

Early Life Adversity, Microbiome, and Inflammatory Responses

Early life adversity has a profound impact on physical and mental health. Because the central nervous and immune systems are not fully mature at birth and continue to mature during the postnatal period, a bidirectional interaction between the central nervous system and the immune system has been hypothesized, with traumatic stressors during childhood being pivotal in priming individuals for later adult psychopathology. Similarly, the microbiome, which regulates both neurodevelopment and immune function, also matures during childhood, rendering this interaction between the brain and the immune system even more complex. In this review, we provide evidence for the role of the immune response and the microbiome in the deleterious effects of early life adversity, both in humans and rodent models.

Sex differences in the relationship between depression and Alzheimer's disease-mechanisms, genetics, and therapeutic opportunities

Depression and Alzheimer's disease (AD) are prevalent neuropsychiatric disorders with intriguing epidemiological overlaps. Their interrelation has recently garnered widespread attention. Empirical evidence indicates that depressive disorders significantly contribute to AD risk, and approximately a quarter of AD patients have comorbid major depressive disorder, which underscores the bidirectional link between AD and depression. A growing body of evidence substantiates pervasive sex differences in both AD and depression: both conditions exhibit a higher incidence among women than among men. However, the available literature on this topic is somewhat fragmented, with no comprehensive review that delineates sex disparities in the depression-AD correlation. In this review, we bridge these gaps by summarizing recent progress in understanding sex-based differences in mechanisms, genetics, and therapeutic prospects for depression and AD. Additionally, we outline key challenges in the field, holding potential for improving treatment precision and efficacy tailored to male and female patients' distinct needs.

Growth differentiation factor 15 and malnutrition in older adults

OBJECTIVES

Growth differentiation factor 15 (GDF-15) levels increase due to systemic inflammation and chronic disease burden. Since these biological processes are pathogenic factors of malnutrition, we examined the prospective association between GDF-15 serum levels and subsequent malnutrition in older adults.

METHODS

We used data from 723 women and 735 men aged ≥65 years [mean age (SD): 71.3 (4.18) years] participating in the Seniors-ENRICA-2 cohort, who were followed-up for 2.2 years. Malnutrition was assessed with the Mini Nutritional Assessment-Short form (MNA-SF), where a 12-14 score indicates normal nutritional status, an 8-11 score indicates at risk of malnutrition, and a 0-7 score malnutrition. Associations of GDF-15 and malnutrition were analyzed, separately in women and men, using linear and logistic regression and adjusted for the main potential confounders.

RESULTS

The mean (SD) MNA-SF score at baseline was 13.2 (1.34) for women and 13.5 (1.13) for men. Incident malnutrition (combined endpoint "at risk of malnutrition or malnutrition") over 2.2 years was identified in 55 (9.7%) of women and 38 (5.4%) of men. In women, GDF-15 was linearly associated with a decrease in the MNA-SF score; mean differences (95% confidence interval) in the MNA-SF score were -0.07 (-0.13; -0.01) points per 25% increase in GDF-15, and -0.49 (-0.83; -0.16) for the highest versus lowest quartile of GDF-15. Also in women, GDF-15 was linearly associated with a higher malnutrition incidence, with odds ratio (95% confidence interval) of 1.24 (1.06; 1.46) per 25% increment in GDF-15 and of 3.05 (1.21; 7.65) for the highest versus lowest quartile of GDF-15. Results were similar after excluding subjects with cardiovascular disease and diabetes. No association of GDF-15 with changes in MNA score or malnutrition incidence was found in men.

CONCLUSION

Higher serum GDF-15 concentrations are associated with worsening nutritional status in older women. Further studies should elucidate the reasons for the sex differences in this association and explore the therapeutic potential of modifying GDF-15 to prevent malnutrition.

Stress, pain, anxiety, and depression in endometriosis-Targeting glial activation and inflammation

Endometriosis (EM) is a gynecological inflammatory disease often accompanied by stress, chronic pelvic pain (CPP), anxiety, and depression, leading to a diminished quality of life. This review aims to discuss the relationship between systemic and local inflammatory responses in the central nervous system (CNS), focusing on glial dysfunctions (astrocytes and microglia) as in critical brain regions involved in emotion, cognition, pain processing, anxiety, and depression. The review presents that EM is connected to increased levels of pro-inflammatory cytokines in the circulation. Additionally, chronic stress and CPP as stressors may contribute to the dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, depleting the production of inflammatory mediators in the circulatory system and the brain. The systemic cytokines cause blood-brain barrier (BBB) breakdown, activate microglia in the brain, and lead to neuroinflammation. Furthermore, CPP may induce neuronal morphological alterations in critical regions through central sensitization and the activation of glial cells. The activation of glial cells, particularly the polarization of microglia, leads to the activation of the NLRP3 inflammasome and the overproduction of inflammatory cytokines. These inflammatory cytokines interact with the signaling pathways involved in neural plasticity. Additionally, persistent inflammatory conditions in the brain lead to neuronal death, which is correlated with a reduced volume of key brain regions such as the hippocampus. This review highlights the involvement of glial cells in the pathogenesis of the mental comorbidities of EM (i.e., pain, anxiety, and depression) and to discuss potential therapeutic approaches for targeting the inflammation and activation of microglia in key brain regions.

Chronic variable stress leads to sex specific gut microbiome alterations in mice

Stress has been implicated in the incidence and severity of psychiatric and gastrointestinal disorders. The immune system is capable of modulating the activity and composition of the gut following stress and vice versa. In this study we sought to examine the sequential relationship between immune signaling and microbiome composition occurring in male and female mice over time using a variable stress paradigm. Tissue was collected prior to, during, and after the stress paradigm from the same mice. Cytokines from plasma and brain were quantified using a multiplexed cytokine assay. Fecal samples were collected at the same timepoints and 16S rRNA amplicon sequencing was performed to determine the relative abundance of microbiota residing in the guts of stressed and control mice. We found sex differences in the response of the gut microbiota to stress following 28 days of chronic variable stress but not 6 days of sub-chronic variable stress. Immune activation was quantified in the nucleus accumbens immediately following Sub-chronic variable when alterations of gut composition had not yet occurred. In both sexes, 28 days of stress induced significant changes in the proportion of Erysipelotrichaceae and Lactobacillaceae, but in opposite directions for male and female mice. Alterations to the gut microbiome in both sexes were associated with changes in cytokines related to eosinophilic immune activity. Our use of an animal stress model reveals the immune mechanisms that may underly changes in gut microbiome composition during and after stress. This study reveals potential drug targets and microbiota of interest for the intervention of stress related conditions.

Stress increases hepatic release of lipocalin 2 which contributes to anxiety-like behavior in mice

Chronic stress induces anxiety disorders via both neural pathways and circulating factors. Although many studies have elucidated the neural circuits involved in stress-coping behaviors, the origin and regulatory mechanism of peripheral cytokines in behavioural regulation under stress conditions are not fully understood. Here, we identified a serum cytokine, lipocalin 2 (LCN2), that was upregulated in participants with anxiety disorders. Using a mouse model of chronic restraint stress (CRS), circulating LCN2 was found to be related to stress-induced anxiety-like behaviour via modulation of neural activity in the medial prefrontal cortex (mPFC). These results suggest that stress increases hepatic LCN2 via a neural pathway, leading to disrupted cortical functions and behaviour.

Associations of diet quality and daily free sugar intake with depressive and anxiety symptoms among Chinese adolescents

BACKGROUND

Assessing diet quality has been challenging, and the associations of diet quality and daily free sugar intake with depressive and/or anxiety symptoms have shown inconsistency.

METHODS

A total of 1749 students aged 12-16 years were recruited using stratified random cluster sampling across three cities in China. The overall Global Dietary Recommendations (GDR) score, a novel indicator of diet quality, was constructed using the low-burden Diet Quality Questionnaire. Free sugar intake, including from beverages and foods, was measured using the Food Frequency Questionnaire. Daily free sugar intake was divided into low, medium, and high categories based on the latest version of the dietary guidelines for Chinese residents. Binomial and multinominal logistic regression analyses were used to examine the associations of the overall GDR score and daily free sugar intake categories or different sources of free sugar intake with depressive and/or anxiety symptoms.

RESULTS

The overall GDR score was negatively associated with depressive symptoms (adjusted odds ratio[aOR] = 0.92, 95%CI: 0.87-0.98) and anxiety symptoms (0.95, 0.90-0.99), particularly with comorbid depression and anxiety (0.90, 0.84-0.97). Conversely, daily free sugar intake was positively associated with symptoms of depression and/or anxiety, the multiple aOR for symptoms depression or anxiety were significantly increased with higher daily free sugar intake (all Ptrend < 0.05). Both free sugar from beverages and from foods were positively associated with depressive and/or anxiety symptoms. These associations were consistent between males and females.

LIMITATIONS

Cross-sectional design and self-reported symptoms.

CONCLUSIONS

Diet quality was negatively associated with symptoms of depression or anxiety, especially with comorbid symptoms among adolescents. Daily free sugar intake, regardless of its sources, was positively associated with symptoms of depression and/or anxiety.

Lifestyle and demographic associations with 47 inflammatory and vascular stress biomarkers in 9876 blood donors

BACKGROUND

The emerging use of biomarkers in research and tailored care introduces a need for information about the association between biomarkers and basic demographics and lifestyle factors revealing expectable concentrations in healthy individuals while considering general demographic differences.

METHODS

A selection of 47 biomarkers, including markers of inflammation and vascular stress, were measured in plasma samples from 9876 Danish Blood Donor Study participants. Using regression models, we examined the association between biomarkers and sex, age, Body Mass Index (BMI), and smoking.

RESULTS

Here we show that concentrations of inflammation and vascular stress biomarkers generally increase with higher age, BMI, and smoking. Sex-specific effects are observed for multiple biomarkers.

CONCLUSION

This study provides comprehensive information on concentrations of 47 plasma biomarkers in healthy individuals. The study emphasizes that knowledge about biomarker concentrations in healthy individuals is critical for improved understanding of disease pathology and for tailored care and decision support tools.

Neuroinflammation and Post-Stroke Depression: Focus on the Microglia and Astrocytes

Post-stroke depression (PSD), a frequent and disabling complication of stroke, has a strong impact on almost thirty percent of stroke survivors. The pathogenesis of PSD is not completely clear so far. Neuroinflammation following stroke is one of underlying mechanisms that involves in the pathophysiology of PSD and plays an important function in the development of depression and is regarded as a sign of depression. During the neuroinflammation after ischemic stroke onset, both astrocytes and microglia undergo a series of morphological and functional changes and play pro-inflammatory or anti-inflammatory effect in the pathological process of stroke. Importantly, astrocytes and microglia exert dual roles in the pathological process of PSD due to the phenotypic transformation. We summarize the latest evidence of neuroinflammation involving in PSD in this review, focus on the phenotypic transformation of microglia and astrocytes following ischemic stroke and reveal the dual roles of both microglia and astrocytes in the PSD via modulating the neuroinflammation.

Neuroinflammation and acquired traumatic CNS injury: a mini review

Acquired traumatic central nervous system (CNS) injuries, including traumatic brain injury (TBI) and spinal cord injury (SCI), are devastating conditions with limited treatment options. Neuroinflammation plays a pivotal role in secondary damage, making it a prime target for therapeutic intervention. Emerging therapeutic strategies are designed to modulate the inflammatory response, ultimately promoting neuroprotection and neuroregeneration. The use of anti-inflammatory agents has yielded limited support in improving outcomes in patients, creating a critical need to re-envision novel approaches to both quell deleterious inflammatory processes and upend the progressive cycle of neurotoxic inflammation. This demands a comprehensive exploration of individual, age, and sex differences, including the use of advanced imaging techniques, multi-omic profiling, and the expansion of translational studies from rodents to humans. Moreover, a holistic approach that combines pharmacological intervention with multidisciplinary neurorehabilitation is crucial and must include both acute and long-term care for the physical, cognitive, and emotional aspects of recovery. Ongoing research into neuroinflammatory biomarkers could revolutionize our ability to predict, diagnose, and monitor the inflammatory response in real time, allowing for timely adjustments in treatment regimens and facilitating a more precise evaluation of therapeutic efficacy. The management of neuroinflammation in acquired traumatic CNS injuries necessitates a paradigm shift in our approach that includes combining multiple therapeutic modalities and fostering a more comprehensive understanding of the intricate neuroinflammatory processes at play.

Single nuclei transcriptomics in human and non-human primate striatum in opioid use disorder

In brain, the striatum is a heterogenous region involved in reward and goal-directed behaviors. Striatal dysfunction is linked to psychiatric disorders, including opioid use disorder (OUD). Striatal subregions are divided based on neuroanatomy, each with unique roles in OUD. In OUD, the dorsal striatum is involved in altered reward processing, formation of habits, and development of negative affect during withdrawal. Using single nuclei RNA-sequencing, we identified both canonical (e.g., dopamine receptor subtype) and less abundant cell populations (e.g., interneurons) in human dorsal striatum. Pathways related to neurodegeneration, interferon response, and DNA damage were significantly enriched in striatal neurons of individuals with OUD. DNA damage markers were also elevated in striatal neurons of opioid-exposed rhesus macaques. Sex-specific molecular differences in glial cell subtypes associated with chronic stress were found in OUD, particularly female individuals. Together, we describe different cell types in human dorsal striatum and identify cell type-specific alterations in OUD.

Associations of classical HLA alleles with depression and anxiety

Immune dysregulation has been widely observed in patients with psychiatric disorders. This study aims to examine the association between HLA alleles and depression and anxiety. Using data from the UK Biobank, we performed regression analyses to assess the association of 359 HLA alleles with depression and anxiety, as determined by Patient Health Questionnaire (PHQ) score (n = 120,033), self-reported depression (n = 121,685), general anxiety disorder (GAD-7) score (n = 120,590), and self-reported anxiety (n = 108,310). Subsequently, we conducted gene environmental interaction study (GEIS) to evaluate the potential effects of interactions between HLA alleles and environmental factors on the risk of depression and anxiety. Sex stratification was implemented in all analysis. Our study identified two significant HLA alleles associated with self-reported depression, including HLA-C*07:01 (β = -0.015, p = 5.54 × 10-5 ) and HLA-B*08:01 (β = -0.015, p = 7.78 × 10-5 ). Additionally, we identified four significant HLA alleles associated with anxiety score, such as HLA-DRB1*07:01 (β = 0.084, p = 9.28 × 10-5 ) and HLA-B*57:01 (β = 0.139, p = 1.22 × 10-4 ). GEIS revealed that certain HLA alleles interacted with environmental factors to influence mental health outcomes. For instance, HLA-A*02:07 × cigarette smoking was associated with depression score (β = 0.976, p = 1.88 × 10-6 ). Moreover, sex stratification analysis revealed significant sex-based differences in the interaction effects of certain HLA alleles with environmental factors. Our findings indicate the considerable impact of HLA alleles on the risks of depression and anxiety, providing valuable insights into the functional relevance of immune dysfunction in these conditions.

Associations of Frailty with Neuropsychiatric Symptoms of Alzheimer's Disease: A Longitudinal Study

Background

Frailty is a vulnerability state increasing the risk of many adverse health outcomes, but little is known about the effects of frailty on neuropsychiatric health.

Objective

To explore the associations between frailty and the risk of neuropsychiatric symptoms (NPSs) in Alzheimer's disease (AD), especially in its different clinical stages.

Methods

We included 2,155 individuals assessed using modified frailty index-11 (mFI-11), Neuropsychiatric Inventory (NPI) and Neuropsychiatric Inventory Questionnaire (NPI-Q) in the Alzheimer's Disease Neuroimaging Initiative (ADNI). The relationships between frailty and NPSs were explored with logistic regression models and Cox proportional hazard regression models. Causal mediation analyses were conducted to explore the mediation factors between frailty and NPSs.

Results

Among mild cognitive impairment (MCI) participants, frailty was cross-sectionally associated with an increased risk of apathy, and longitudinally associated with increased risk of depression and apathy. Among AD participants, frailty was cross-sectionally associated with increased risk of depression and anxiety, and longitudinally associated with an increased risk of apathy. Among participants with cognitive progression, frailty was associated with increased risk of depression and apathy. In MCI participants, the influence of frailty on NPSs was partially mediated by hippocampus volume, whole brain volume, and monocytes, with mediating proportions ranging from 8.40% to 9.29%.

Conclusions

Frailty was associated with NPSs such as depression, anxiety, and apathy among MCI, AD, and cognitive progression participants. Atrophy of the hippocampus and whole brain, as well as peripheral immunity may be involved in the potential mechanisms underlying the above associations.

Thirty Risk Factors for Alzheimer's Disease Unified by a Common Neuroimmune-Neuroinflammation Mechanism

One of the major obstacles confronting the formulation of a mechanistic understanding for Alzheimer's disease (AD) is its immense complexity-a complexity that traverses the full structural and phenomenological spectrum, including molecular, macromolecular, cellular, neurological and behavioural processes. This complexity is reflected by the equally complex diversity of risk factors associated with AD. However, more than merely mirroring disease complexity, risk factors also provide fundamental insights into the aetiology and pathogenesis of AD as a neurodegenerative disorder since they are central to disease initiation and subsequent propagation. Based on a systematic literature assessment, this review identified 30 risk factors for AD and then extended the analysis to further identify neuroinflammation as a unifying mechanism present in all 30 risk factors. Although other mechanisms (e.g., vasculopathy, proteopathy) were present in multiple risk factors, dysfunction of the neuroimmune-neuroinflammation axis was uniquely central to all 30 identified risk factors. Though the nature of the neuroinflammatory involvement varied, the activation of microglia and the release of pro-inflammatory cytokines were a common pathway shared by all risk factors. This observation provides further evidence for the importance of immunopathic mechanisms in the aetiopathogenesis of AD.

The hypothalamic steroidogenic pathway mediates susceptibility to inflammation-evoked depression in female mice

BACKGROUND

Depression is two-to-three times more frequent among women. The hypothalamus, a sexually dimorphic area, has been implicated in the pathophysiology of depression. Neuroinflammation-induced hypothalamic dysfunction underlies behaviors associated with depression. The lipopolysaccharide (LPS)-induced mouse model of depression has been well-validated in numerous laboratories, including our own, and is widely used to investigate the relationship between neuroinflammation and depression. However, the sex-specific differences in metabolic alterations underlying depression-associated hypothalamic neuroinflammation remain unknown.

METHODS

Here, we employed the LPS-induced mouse model of depression to investigate hypothalamic metabolic changes in both male and female mice using a metabolomics approach. Through bioinformatics analysis, we confirmed the molecular pathways and biological processes associated with the identified metabolites. Furthermore, we employed quantitative real-time PCR, enzyme-linked immunosorbent assay, western blotting, and pharmacological interventions to further elucidate the underlying mechanisms.

RESULTS

A total of 124 and 61 differential metabolites (DMs) were detected in male and female mice with depressive-like behavior, respectively, compared to their respective sex-matched control groups. Moreover, a comparison between female and male model mice identified 37 DMs. We capitalized on biochemical clustering and functional enrichment analyses to define the major metabolic changes in these DMs. More than 55% of the DMs clustered into lipids and lipid-like molecules, and an imbalance in lipids metabolism was presented in the hypothalamus. Furthermore, steroidogenic pathway was confirmed as a potential sex-specific pathway in the hypothalamus of female mice with depression. Pregnenolone, an upstream component of the steroid hormone biosynthesis pathway, was downregulated in female mice with depressive-like phenotypes but not in males and had considerable relevance to depressive-like behaviors in females. Moreover, exogenous pregnenolone infusion reversed depressive-like behaviors in female mice with depression. The 5α-reductase type I (SRD5A1), a steroidogenic hub enzyme involved in pregnenolone metabolism, was increased in the hypothalamus of female mice with depression. Its inhibition increased hypothalamic pregnenolone levels and ameliorated depressive-like behaviors in female mice with depression.

CONCLUSIONS

Our study findings demonstrate a marked sexual dimorphism at the metabolic level in depression, particularly in hypothalamic steroidogenic metabolism, identifying a potential sex-specific pathway in female mice with depressive-like behaviors.

Investigating the Role of Race and Stressful Life Events on the Smoking Patterns of Pregnant and Postpartum Women in the United States: A Multistate Pregnancy Risk Assessment Monitoring System Phase 8 (2016-2018) Analysis

OBJECTIVE

To examine the smoking patterns of women who experienced stressful life events and the impact of racial disparities on the relationship between stressful life events, and prenatal/ postpartum smoking.

METHODS

The study analyzed data from the Pregnancy Risk Assessment Monitoring System Phase 8 (2016-2018) survey across five states (CT, LA, MA, MO, WI). Four stressful life event categories were created using thirteen affiliated questions: financial, trauma, partner, and emotional. We assessed: 1) the association between smoking and stressful life events, 2) the impact of race on the relation between smoking and stressful life events, and 3) the long-term effects of smoking on health by assessing the association between smoking and maternal morbidity. Bivariate statistics and multivariate Poisson regression models were conducted.

RESULTS

A total of 24,209 women from five states were included. 8.9% of respondents reported smoking during pregnancy, and 12.7% reported smoking postpartum. There was a significant association between all stressful life events and smoking. Trauma stressful life event had the strongest association with smoking during pregnancy (adjusted PR=2.01; CI: 1.79-2.27) and postpartum (adjusted PR= 1.80; CI: 1.64-1.98). Race and stressful life event interaction effects on smoking had varied significant findings, but at least one racial/ ethnic minority group (Black, Hispanic, Asian) had a higher smoking prevalence than non-Hispanic White per stressful life event category. Lastly, the prevalence of maternal morbidity was higher for smoking during pregnancy (adjusted PR= 1.28; CI: 1.19-1.38) and postpartum (adjusted PR= 1.30; CI: 1.22-1.38) compared to no smoking.

CONCLUSIONS FOR PRACTICE

Culturally congruent, multi-disciplinary care teams are needed to address both clinical and social needs to reduce stressful life events and smoking. Screenings for stress should be standardized with a referral system in place to provide ongoing support.

Sex-specific immune-inflammatory markers and lipoprotein profile in patients with anhedonia with unipolar and bipolar depression

BACKGROUND

Anhedonia is a core symptom in patients with unipolar and bipolar depression. However, sex-specific markers reflecting biological heterogeneity are lacking. Emerging evidence suggests that sex differences in immune-inflammatory markers and lipoprotein profiles are associated with anhedonia.

METHODS

The demographic and clinical data, immune-inflammatory markers (CD3, CD4, and CD8), and lipoprotein profiles [TC, TG, LDL-C, HDL-C, lipoprotein(a) Lp (a)] of 227 patients with unipolar and bipolar depression were collected. The Hamilton Depression Rating Scale (HAMD) and Snaith-Hamilton Pleasure Scale (SHAPS) were used to assess depression and anhedonia symptoms. Data were analyzed using ANOVA, logistic regression, and receiver operating characteristic curves.

RESULTS

Male patients in the anhedonia group had higher levels of CD3, CD4, and CD8, and lower levels of Lp (a) than the non-anhedonia group, while no significant difference was identified in female patients with and without anhedonia. Logistic regression analysis showed that CD3, CD4, CD8, and Lp (a) levels were associated with anhedonia in male patients. Furthermore, the combination of CD3, CD4, CD8, and Lp (a) had the strongest predictive value for distinguishing anhedonia in male patients than individual parameters.

CONCLUSIONS

We identified sex-specific associations between immune-inflammatory markers, lipoprotein profiles, and anhedonia in patients with unipolar and bipolar depression. The combination of CD3, CD4, CD8, and Lp (a) might be a possible biomarker for identifying anhedonia in male patients with unipolar and bipolar depression.

Noteworthy perspectives on microglia in neuropsychiatric disorders

Microglia are so versatile that they not only provide immune surveillance for central nervous system, but participate in neural circuitry development, brain blood vessels formation, blood-brain barrier architecture, and intriguingly, the regulation of emotions and behaviors. Microglia have a profound impact on neuronal survival, brain wiring and synaptic plasticity. As professional phagocytic cells in the brain, they remove dead cell debris and neurotoxic agents via an elaborate mechanism. The functional profile of microglia varies considerately depending on age, gender, disease context and other internal or external environmental factors. Numerous studies have demonstrated a pivotal involvement of microglia in neuropsychiatric disorders, including negative affection, social deficit, compulsive behavior, fear memory, pain and other symptoms associated with major depression disorder, anxiety disorder, autism spectrum disorder and schizophrenia. In this review, we summarized the latest discoveries regarding microglial ontogeny, cell subtypes or state spectrum, biological functions and mechanistic underpinnings of emotional and behavioral disorders. Furthermore, we highlight the potential of microglia-targeted therapies of neuropsychiatric disorders, and propose outstanding questions to be addressed in future research of human microglia.

Post-stroke depression: epigenetic and epitranscriptomic modifications and their interplay with gut microbiota

Epigenetic and epitranscriptomic modifications that regulate physiological processes of an organism at the DNA and RNA levels, respectively, are novel therapeutic candidates for various neurological diseases. Gut microbiota and its metabolites are known to modulate DNA methylation and histone modifications (epigenetics), as well as RNA methylation especially N6-methyladenosine (epitranscriptomics). As gut microbiota as well as these modifications are highly dynamic across the lifespan of an organism, they are implicated in the pathogenesis of stroke and depression. The lack of specific therapeutic interventions for managing post-stroke depression emphasizes the need to identify novel molecular targets. This review highlights the interaction between the gut microbiota and epigenetic/epitranscriptomic pathways and their interplay in modulating candidate genes that are involved in post-stroke depression. This review further focuses on the three candidates, including brain-derived neurotrophic factor, ten-eleven translocation family proteins, and fat mass and obesity-associated protein based on their prevalence and pathoetiologic role in post-stroke depression.

Sex and cell-specific gene expression in corticolimbic brain regions associated with psychiatric disorders revealed by bulk and single-nuclei RNA sequencing

BACKGROUND

There are sex-specific differences in the prevalence, symptomology and course of psychiatric disorders. However, preclinical models have primarily used males, such that the molecular mechanisms underlying sex-specific differences in psychiatric disorders are not well established.

METHODS

In this study, we compared transcriptome-wide gene expression profiles in male and female rats within the corticolimbic system, including the cingulate cortex, nucleus accumbens medial shell (NAcS), ventral dentate gyrus and the basolateral amygdala (n = 22-24 per group/region).

FINDINGS

We found over 3000 differentially expressed genes (DEGs) in the NAcS between males and females. Of these DEGs in the NAcS, 303 showed sex-dependent conservation DEGs in humans and were significantly enriched for gene ontology terms related to blood vessel morphogenesis and regulation of cell migration. Single nuclei RNA sequencing in the NAcS of male and female rats identified widespread sex-dependent expression, with genes upregulated in females showing a notable enrichment for synaptic function. Female upregulated genes in astrocytes, Drd3+MSNs and oligodendrocyte were also enriched in several psychiatric genome-wide association studies (GWAS).

INTERPRETATION

Our data provide comprehensive evidence of sex- and cell-specific molecular profiles in the NAcS. Importantly these differences associate with anxiety, bipolar disorder, schizophrenia, and cross-disorder, suggesting an intrinsic molecular basis for sex-based differences in psychiatric disorders that strongly implicates the NAcS.

FUNDING

This work was supported by funding from the Hope for Depression Research Foundation (MJM).

Depressive symptoms in younger adults before and during the COVID-19 pandemic: A nationally representative cross-sectional data analysis

OBJECTIVE

Several studies have reported an increased prevalence of depressive symptoms during the coronavirus disease 2019 (COVID-19) pandemic. However, the prevalence of significant depressive symptoms and its associated factors in younger adults remain uncertain. We aimed to investigate this association during the COVID-19 pandemic and make a comparison with the pre-pandemic period.

METHODS

Cross-sectional data from the 2018 and 2020 Korea National Health and Nutrition Examination Surveys were analyzed, and 3281 respondents aged 19-40 years were included. We defined a Patient Health Questionnaire-9 score ≥ 10 as significant depressive symptoms and the categories of depressive symptoms were also classified as none, mild, moderate, and severe.

RESULTS

The prevalence of significant depressive symptoms was higher in the pandemic group (7.4% vs. 4.7%). Furthermore, the prevalence in the pandemic group was higher for all degrees: mild, moderate, and severe depressive symptoms. A multivariable logistic regression indicated that significant depressive symptoms during the pandemic was significantly associated with female sex, low educational attainment, unemployment, chronic medical disease, and being overweight.

CONCLUSIONS

Our findings suggest an increase in depressive symptoms in younger adults during the pandemic. It is necessary to develop policies to provide younger adults with resources to cope with depressive symptoms related to COVID-19 and potential global outbreak of infectious disease.

Sex Differences in the Neurobiology of Stress

This review highlights the existing knowledge and data that explain the physiologic impacts of stress, especially pertaining to neurobiology, and how these impacts differ by sex. Furthermore, this review explains the benefits of interventions aimed at preventing or mitigating the adverse effects of stress, because of both the significant toll of stress on the body and the disproportionate impact of these changes experienced by women.

Sex differences in stress responses among underrepresented minority adolescents at risk for substance use disorder

Adolescence is a period of dramatic physiological changes preparing individuals to face future challenges. Prolonged exposure to stressors during childhood can result in dysregulated stress systems which alter normative physiological progression, leading to exacerbated risk for developing psychiatric disorders. Parental substance use disorder (SUD) is considered a significant childhood stressor which increases risk for the offspring to develop SUD. Thus, it is important to understand stress reactivity among adolescents with parental SUD. We used the Trier Social Stress Task (TSST), which includes a public speech presentation, as an acute stressor. Changes in heart-rate (HR) were measured while disadvantaged minority adolescents with and without a family history (FH+/FH-) of SUD performed the TSST. We investigated sex-specific stress response patterns during the TSST. HR peaked during the speech presentation and was overall higher in females than males. Changes in HR measures between baseline and speech showed an interaction between biological sex and FH group. Specifically, FH- females and FH+ males had significantly larger positive HR changes than FH- males. These results suggest that male and female adolescents with parental SUD have atypical, but divergent changes in stress reactivity that could explain their increased risk for developing SUD via different sexually dimorphic mechanisms.

Targeting inflammatory pathways for treatment of the major depressive disorder

Current treatments modalities for major depressive disorder (MDD) mainly target the monoaminergic neurotransmission. However, the therapeutic inadequacy and adverse effects confine the use of these conventional antidepressants to a limited subset of MDD patients. The classical antidepressants are increasingly proving unsatisfactory in tackling the treatment-resistant depression (TRD). Hence, the focus of treatment is shifting to alternative pathogenic pathways involved in depression. Preclinical and clinical evidences accumulated across the last decades have unequivocally affirmed the causative role of immuno-inflammatory pathways in the progression of depression. There is an upsurge in the clinical evaluations of the drugs having anti-inflammatory effects as antidepressants. This review highlights the molecular mechanisms connecting the inflammatory pathways to the MDD and current clinical status of inflammation modulating drugs in the treatment of MDD.

Sex differences in the efficacy and safety of SARS-CoV-2 vaccination in residents of long-term care facilities: insights from the GeroCovid Vax study

Despite the reported sex-related variations in the immune response to vaccination, whether the effects of SARS-CoV-2 vaccination differ by sex is still under debate, especially considering old vulnerable individuals, such as long-term care facilities (LTCFs) residents. This study aimed to evaluate COVID-19 infections, adverse events, and humoral response after vaccination in a sample of LTCF residents. A total of 3259 LTCF residents (71% females; mean age: 83.4 ± 9.2 years) were enrolled in the Italian-based multicenter GeroCovid Vax study. We recorded the adverse effects occurring during the 7 days after vaccine doses and COVID-19 cases over 12 months post-vaccination. In a subsample of 524 residents (69% females), pre- and post-vaccination SARS-CoV-2 trimeric S immunoglobulin G (Anti-S-IgG) were measured through chemiluminescent assays at different time points. Only 12.1% of vaccinated residents got COVID-19 during the follow-up, without any sex differences. Female residents were more likely to have local adverse effects after the first dose (13.3% vs. 10.2%, p = 0.018). No other sex differences in systemic adverse effects and for the following doses were recorded, as well as in anti-S-IgG titer over time. Among the factors modifying the 12-month anti-S-IgG titers, mobility limitations and depressive disorder were more likely to be associated with higher and lower levels in the antibody response, respectively; a significantly lower antibody titer was observed in males with cardiovascular diseases and in females with diabetes or cognitive disorders. The study suggests that, among LTCF residents, SARS-CoV-2 vaccination was effective regardless of sex, yet sex-specific comorbidities influenced the antibody response. Local adverse reactions were more common in females.

Gestational 1-nitropyrene exposure causes anxiety-like behavior partially by altering hippocampal epigenetic reprogramming of synaptic plasticity in male adult offspring

1-Nitropyrene (1-NP), a typical nitro-polycyclic aromatic hydrocarbon, is a developmental toxicant. This study was to evaluate gestational 1-NP-induced anxiety-like behavior in male adult offspring. Pregnant mice were orally administered to 1-NP daily throughout pregnancy. Anxiety-like behaviors, as determined by Elevated Plus-Maze (EPM) and Open-Field Test (OFT), were showed in male adult offspring whose mothers were exposed to 1-NP. Gestational 1-NP exposure reduced dendritic arborization, dendritic length and dendritic spine density in ventral hippocampus of male adult offspring. Additional experiments showed that gephyrin, an inhibitory synaptic marker, was reduced in fetal forebrain and hippocampus in male adult offspring. Nrg1 and Erbb4, two gephyrin-related genes, were reduced in 1-NP-exposed fetuses. Accordingly, 5hmC contents in two CpG sites (32008909 and 32009239) of Nrg1 gene and three CpG sites (69107743, 69107866 and 69107899) of Erbb4 gene were decreased in 1-NP-exposed fetuses. Mechanistically, ten-eleven translocation (TET) activity and alpha-ketoglutarate (α-KG) content were decreased in 1-NP-exposed fetal forebrain. Supplementation with α-KG alleviated 1-NP-induced downregulation of gephyrin-related genes, prevented hippocampal synaptic damage, and improved anxiety-like behavior in male adult offspring. These results indicate that early-life 1-NP exposure causes anxiety-like behavior in male adulthood partially by altering hippocampal epigenetic reprogramming of synaptic plasticity.

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.

Association between immune cells in peripheral blood and psychiatric symptoms

Background

There are bidirectional associations between immunological dysfunction and psychiatric symptoms. However, the associations between the levels of immune cells in the peripheral blood and psychiatric symptoms remain unclear. The present study aimed to evaluate levels of immune cells in peripheral blood in people with positive psychiatric symptoms.

Methods

This retrospective study analyzed data from routine blood tests and psychopathology and sleep quality assessments. Data were compared between a group of 45 patients with de novo psychological symptoms and 225 matched controls.

Results

Patients with psychiatric symptoms had higher white blood cell and neutrophil counts compared with controls. However, in a subgroup analysis, neutrophil counts were significantly higher than in controls only in patients with multiple psychiatric symptoms. Furthermore, monocyte counts were significantly higher in patients with multiple psychiatric symptoms than in controls. Further, sleep quality was lower in patients with psychiatric symptoms than in controls.

Conclusion

White blood cell and neutrophil counts in the peripheral blood of patients with psychiatric symptoms were significantly higher and sleep quality was significantly lower than in controls. Participants with multiple psychiatric symptoms showed more significant differences in peripheral blood immune cell counts than other subgroups. These results provided evidence for the relationship between psychiatric symptoms, immunity, and sleep.

Oleoylethanolamide restores stress-induced prepulse inhibition deficits and modulates inflammatory signaling in a sex-dependent manner

RATIONALE

Social stress contributes to the development of depressive and anxiety symptomatology and promotes pro-inflammatory signaling in the central nervous system. In this study, we explored the effects of a lipid messenger with anti-inflammatory properties - oleoylethanolamide (OEA) - on the behavioral deficits caused by social stress in both male and female mice.

METHODS

Adult mice were assigned to an experimental group according to the stress condition (control or stress) and treatment (vehicle or OEA, 10 mg/kg, i.p.). Male mice in the stress condition underwent a protocol consisting of four social defeat (SD) encounters. In the case of female mice, we employed a procedure of vicarious SD. After the stress protocol resumed, anxiety, depressive-like behavior, social interaction, and prepulse inhibition (PPI) were assessed. In addition, we characterized the stress-induced inflammatory profile by measuring IL-6 and CX3CL1 levels in the striatum and hippocampus.

RESULTS

Our results showed that both SD and VSD induced behavioral alterations. We found that OEA treatment restored PPI deficits in socially defeated mice. Also, OEA affected differently stress-induced anxiety and depressive-like behavior in male and female mice. Biochemical analyses showed that both male and female stressed mice showed increased levels of IL-6 in the striatum compared to control mice. Similarly, VSD female mice exhibited increased striatal CX3CL1 levels. These neuroinflammation-associated signals were not affected by OEA treatment.

CONCLUSIONS

In summary, our results confirm that SD and VSD induced behavioral deficits together with inflammatory signaling in the striatum and hippocampus. We observed that OEA treatment reverses stress-induced PPI alterations in male and female mice. These data suggest that OEA can exert a buffering effect on stress-related sensorimotor gating behavioral processing.

Spinal cord injury in mice amplifies anxiety: A novel light-heat conflict test exposes increased salience of anxiety over heat

Spinal cord injury (SCI) predisposes individuals to anxiety and chronic pain. Anxiety- and pain-like behavior after SCI can be tested in rodents, yet commonly used tests assess one variable and may not replicate effects of SCI or sex differences seen in humans. Thus, novel preclinical tests should be optimized to better evaluate behaviors relating to anxiety and pain. Here, we use our newly developed conflict test - the Thermal Increments Dark-Light (TIDAL) test - to explore how SCI affects anxiety- vs. pain-like behavior, and whether sex affects post-SCI behavior. The TIDAL conflict test consists of two plates connected by a walkway; one plate remains illuminated and at an isothermic temperature, whereas the other plate is dark but is heated incrementally to aversive temperatures. A control mice thermal place preference test was also performed in which both plates are illuminated. Female and male mice received moderate T9 contusion SCI or remained uninjured. At 7 days post-operative (dpo), mice with SCI increased dark plate preference throughout the TIDAL conflict test compared to uninjured mice. SCI increased dark plate preference for both sexes, although female (vs. male) mice remained on the heated-dark plate to higher temperatures. Mice with SCI that repeated TIDAL at 7 and 21 dpo showed reduced preference for the dark-heated plate at 21 dpo. Overall, in female and male mice, SCI enhances the salience of anxiety (vs. heat sensitivity). The TIDAL conflict test meets a need for preclinical anxiety- and pain-related tests that recapitulate the human condition; thus, future rodent behavioral studies should incorporate TIDAL or other conflict tests to help understand and treat neurologic disorders.

The characteristics and effects of suicide attempters' suicidality levels in gender differences

Objective

The causal reasons for gender differences in suicide attempt and suicide death have been addressed by previous studies: Some emphasized suicidal intent, while others focused on method lethality. The present study is to examine the effects of suicidality levels defined as severity of intent and method lethality on gender differences.

Methods

The data were collected through Korea Foundation for Suicide Prevention (KFSP). Trained interviewers categorized a total of 1,269 patients' responses to questions regarding death wishes and the chosen methods: 1) severe (29.1%), 2) moderate (31.3%), and 3) mild (39.6%), and looked into their characteristics and risk factors related to gender.

Results

The severe group showed no gender differences in the choice of lethal methods, that is 59.4% men and 46.9% women used fatal methods such as hanging or chemical poisoning (p = 0.075). In contrast, moderate and mild groups showed gender differences (p = 0.001, respectively). Most women in the moderate group chose drug poisoning (69.1%) rather than hanging (1.0%) or pesticide poisoning (3.9%). The mild group showed similar results.

Conclusion

The present study examined the contrasting effects of suicidality levels on gender differences in suicide attempts: The severe group fail to reach significant differences, whereas the other two groups did. The future study on suicide attempt should be focused on the severe group whose characteristics were much closer to the actual suicide. The present findings have useful implications for gender-free prevention program.

Sex differences in childhood maltreatment, inflammation, and adulthood depression: A network analysis

Background

Efforts to improve treatment for adults with major depression (MD) and childhood maltreatment (CM) have identified inflammation as a potential target to improve health. Network models have emerged as a new way to understand the relationship between depressive symptoms and inflammation. However, none have accounted for the role of childhood maltreatment in the link between depressive symptoms and inflammation, or sex differences commonly found in these constructs.

Methods

Data from two waves of the Midlife Development in the United States study were used in this study (N = 1917). The Center for Epidemiological Studies Depression (CES-D) scale and Childhood Trauma Questionnaire, and six inflammation markers served as nodes in an undirected psychometric network analysis. Edges between nodes were calculated using partial Spearman's correlation. Separate networks were modeled for males and females.

Results

The total network revealed several associations between nodes of CM, MD, and inflammation, with emotional abuse having a strong association with somatic complaints. Network comparison testing revealed male-female network invariance, with several edge differences between male and female networks. Males and females showed differences in associations across inflammatory markers and depressive symptom clusters, particularly among somatic complaints and interpersonal difficulties.

Conclusions

Specific associations between dimensions of inflammation, CM, and MD may represent important targets for treatment. Network models disaggregated by sex showed that males and females may have fundamentally different associations between these constructs, suggesting that future studies should consider sex-specific interventions.

Gut Microbiota is Associated with Aging-Related Processes of a Small Mammal Species under High-Density Crowding Stress

Humans and animals frequently encounter high-density crowding stress, which may accelerate their aging processes; however, the roles of gut microbiota in the regulation of aging-related processes under high-density crowding stress remain unclear. In the present study, it is found that high housing density remarkably increases the stress hormone (corticosterone), accelerates aging-related processes as indicated by telomere length (in brain and liver cells) and DNA damage or inflammation (as revealed by tumor necrosis factor-α and interleukin-10 levels), and reduces the lifespan of Brandt's vole (Lasiopodomys brandtii). Fecal microbiota transplantation from donor voles of habitats with different housing densities induces similar changes in aging-related processes in recipient voles. The elimination of high housing density or butyric acid administration delays the appearance of aging-related markers in the brain and liver cells of voles housed at high-density. This study suggests that gut microorganisms may play a significant role in regulating the density-dependent aging-related processes and subsequent population dynamics of animals, and can be used as potential targets for alleviating stress-related aging in humans exposed to high-density crowding stress.

A consideration of the increased risk of schizophrenia due to prenatal maternal stress, and the possible role of microglia

Schizophrenia is caused by interaction of a combination of genetic and environmental factors. Of the latter, prenatal exposure to maternal stress is reportedly associated with elevated disease risk. The main orchestrators of inflammatory processes within the brain are microglia, and aberrant microglial activation/function has been proposed to contribute to the aetiology of schizophrenia. Here, we evaluate the epidemiological and preclinical evidence connecting prenatal stress to schizophrenia risk, and consider the possible mediating role of microglia in the prenatal stress-schizophrenia relationship. Epidemiological findings are rather consistent in supporting the association, albeit they are mitigated by effects of sex and gestational timing, while the evidence for microglial activation is more variable. Rodent models of prenatal stress generally report lasting effects on offspring neurobiology. However, many uncertainties remain as to the mechanisms underlying the influence of maternal stress on the developing foetal brain. Future studies should aim to characterise the exact processes mediating this aspect of schizophrenia risk, as well as focussing on how prenatal stress may interact with other risk factors.

Sex differences in neuroimmunoendocrine communication. Involvement on longevity

Endocrine, nervous, and immune systems work coordinately to maintain the global homeostasis of the organism. They show sex differences in their functions that, in turn, contribute to sex differences beyond reproductive function. Females display a better control of the energetic metabolism and improved neuroprotection and have more antioxidant defenses and a better inflammatory status than males, which is associated with a more robust immune response than that of males. These differences are present from the early stages of life, being more relevant in adulthood and influencing the aging trajectory in each sex and may contribute to the different life lifespan between sexes.

Work-Related Psychosocial Factors and Global Cognitive Function: Are Telomere Length and Low-Grade Inflammation Potential Mediators of This Association?

The identification of modifiable factors that could maintain cognitive function is a public health priority. It is thought that some work-related psychosocial factors help developing cognitive reserve through high intellectual complexity. However, they also have well-known adverse health effects and are considered to be chronic psychosocial stressors. Indeed, these stressors could increase low-grade inflammation and promote oxidative stress associated with accelerated telomere shortening. Both low-grade inflammation and shorter telomeres have been associated with a cognitive decline. This study aimed to evaluate the total, direct, and indirect effects of work-related psychosocial factors on global cognitive function overall and by sex, through telomere length and an inflammatory index. A random sample of 2219 participants followed over 17 years was included in this study, with blood samples and data with cognitive function drawn from a longitudinal study of 9188 white-collar workers (51% female). Work-related psychosocial factors were evaluated according to the Demand-Control-Support and the Effort-Reward Imbalance (ERI) models. Global cognitive function was evaluated with the validated Montreal Cognitive Assessment (MoCA). Telomere length and inflammatory biomarkers were measured using standardised protocols. The direct and indirect effects were estimated using a novel mediation analysis method developed for multiple correlated mediators. Associations were observed between passive work or low job control, and shorter telomeres among females, and between low social support at work, ERI or iso-strain, and a higher inflammatory index among males. An association was observed with higher cognitive performance for longer telomeres, but not for the inflammatory index. Passive work overall, and low reward were associated with lower cognitive performance in males; whereas, high psychological demand in both males and females and high job strain in females were associated with a higher cognitive performance. However, none of these associations were mediated by telomere length or the inflammatory index. This study suggests that some work-related psychosocial factors could be associated with shorter telomeres and low-grade inflammation, but these associations do not explain the relationship between work-related psychosocial factors and global cognitive function. A better understanding of the biological pathways, by which these factors affect cognitive function, could guide future preventive strategies to maintain cognitive function and promote healthy aging.

Microbiota-ear-brain interaction is associated with generalized anxiety disorder through activation of inflammatory cytokine responses

Introduction

Generalized anxiety disorder (GAD) is one of the most enduring anxiety disorders, being associated with increased systemic inflammation. However, the trigger and mechanisms underlying the activation of inflammatory cytokine responses in GAD remain poorly understood.

Materials and methods

We characterized the ear canal microbiome in GAD patients through 16S rRNA gene sequencing and metagenomic sequencing and identified the serum inflammatory markers in GAD patients. Spearman correlations were applied to test the relationship between the microbiota changes and systemic inflammation.

Results

Our findings showed the higher microbial diversity, accompanied with the significantly increased abundance of Proteobacteria, and decreased abundance of Firmicutes in the ear canal of GAD participants compared to that of the age- and sex-matched healthy controls (HC). Metagenomic sequencing showed that Pseudomonas aeruginosa were significantly increased at species-level in GAD patients. Furthermore, we observed the relative abundance of Pseudomonas aeruginosa was positively associated with elevated systemic inflammatory markers and the severity of disease, suggesting that these ear canal microbiota alterations might be correlated with GAD by activating the inflammatory response.

Conclusions

These findings indicate that microbiota-ear-brain interaction via upregulating inflammatory reaction involve in the development of GAD, as well as suggest that ear canal bacterial communities may be a target for therapeutic intervention.

Endometriosis leads to central nervous system-wide glial activation in a mouse model of endometriosis

BACKGROUND

Chronic pelvic pain (CPP) is a common symptom of endometriosis. Women with endometriosis are also at a high risk of suffering from anxiety, depression, and other psychological disorders. Recent studies indicate that endometriosis can affect the central nervous system (CNS). Changes in the functional activity of neurons, functional magnetic resonance imaging signals, and gene expression have been reported in the brains of rat and mouse models of endometriosis. The majority of the studies thus far have focused on neuronal changes, whereas changes in the glial cells in different brain regions have not been studied.

METHODS

Endometriosis was induced in female mice (45-day-old; n = 6-11/timepoint) by syngeneic transfer of donor uterine tissue into the peritoneal cavity of recipient animals. Brains, spines, and endometriotic lesions were collected for analysis at 4, 8, 16, and 32 days post-induction. Sham surgery mice were used as controls (n = 6/timepoint). The pain was assessed using behavioral tests. Using immunohistochemistry for microglia marker ionized calcium-binding adapter molecule-1 (IBA1) and machine learning "Weka trainable segmentation" plugin in Fiji, we evaluated the morphological changes in microglia in different brain regions. Changes in glial fibrillary acidic protein (GFAP) for astrocytes, tumor necrosis factor (TNF), and interleukin-6 (IL6) were also evaluated.

RESULTS

We observed an increase in microglial soma size in the cortex, hippocampus, thalamus, and hypothalamus of mice with endometriosis compared to sham controls on days 8, 16, and 32. The percentage of IBA1 and GFAP-positive area was increased in the cortex, hippocampus, thalamus, and hypothalamus in mice with endometriosis compared to sham controls on day 16. The number of microglia and astrocytes did not differ between endometriosis and sham control groups. We observed increased TNF and IL6 expression when expression levels from all brain regions were combined. Mice with endometriosis displayed reduced burrowing behavior and hyperalgesia in the abdomen and hind-paw.

CONCLUSION

We believe this is the first report of central nervous system-wide glial activation in a mouse model of endometriosis. These results have significant implications for understanding chronic pain associated with endometriosis and other issues such as anxiety and depression in women with endometriosis.