Old Friends, immunoregulation, and stress resilience

Paradoxical effect of anti-inflammatory drugs on IL-6 mRNA expression in patients with PTSD during treatment

The pathophysiology of posttraumatic stress disorder (PTSD) is associated with the activation of the innate immune system, including cytokines like interleukin 6 (IL-6). However, the role of IL-6 in the etiology and treatment of PTSD still remains elusive. We conducted a prospective controlled trial to investigate the development of IL-6 during psychosomatic treatment in individuals with PTSD in comparison with individuals without PTSD. We assessed IL-6 mRNA expression before and after 2 months of psychosomatic treatment in individuals with and without PTSD. Severities of PTSD and depressive symptoms were assessed in parallel. Linear mixed regression was applied for statistical analysis, including the factors diagnosis PTSD and pre-post treatment after subgrouping for intake of anti-inflammatory drugs. The development of IL-6 mRNA expression during treatment was affected by the use of anti-inflammatory drugs. In the subgroup without intake of anti-inflammatory drugs, no significant statistical treatment effect in individuals with and without PTSD emerged. In the subgroup of individuals taking anti-inflammatory drugs, a significant interaction effect of the factors pre-post treatment and diagnosis PTSD was observed. Whereas IL-6 mRNA expression in individuals without PTSD decreased according to amelioration of symptoms, IL-6 mRNA expression in individuals with PTSD increased significantly during treatment, in opposite direction to symptom severity. Anti-inflammatory drugs might affect IL-6 mRNA expression in individuals with PTSD in a paradoxical way. This study offers a further piece of evidence that IL-6 could be involved in the pathophysiology of PTSD and PTSD-specific immunologic molecular mechanisms.

Factors associated with the psychosis continuum among homeless people: Comparison between natives and migrants in the SAMENTA study

Background

In the last decades, there has been a documented increase in the proportion of migrants among homeless people in Europe. While homelessness is associated with psychosis, little is known about the factors associated with psychosis among migrants in this context.

Methods

Our study analyzed data collected in the SAMENTA cross-sectional survey conducted among 859 adult French-speaking homeless people living in the Greater Paris area. We analyzed the prevalence of psychosis and psychotic-like experiences (PLE) and associated factors by migrant status, using bivariate analysis and multivariable logistic regression models.

Results

Our sample comprised 280 natives and 559 migrants in France. Psychosis was significantly more prevalent among natives (21.6 %) than among migrants (7.5 %) (p = 0.003). The total prevalence of PLE was 30.8% (95 % CI: 24.3 - 38.2), and not statistically different between groups (p = 0.215) or sex (p = 0.528). Adverse events over the past year were associated with the increased odds of psychosis in both groups and with PLE among migrants. Sexual abuse during childhood was associated with both outcomes among natives. Among migrants, exposure to war or life-threatening events increased the odds of psychosis and PLE. Increased odds of psychosis were found among migrants who had been living in France for more than 10 years (OR = 3.34, 95 % CI: 1.41-7.93, p = 0.007).

Conclusion

Differences were found in the factors associated with the psychosis continuum by migrant status, they highlight the impact of experiences related to migration. Prospective studies are needed to better understand these underlying pathways.

SIR+ models: accounting for interaction-dependent disease susceptibility in the planning of public health interventions

Avoiding physical contact is regarded as one of the safest and most advisable strategies to follow to reduce pathogen spread. The flip side of this approach is that a lack of social interactions may negatively affect other dimensions of health, like induction of immunosuppressive anxiety and depression or preventing interactions of importance with a diversity of microbes, which may be necessary to train our immune system or to maintain its normal levels of activity. These may in turn negatively affect a population's susceptibility to infection and the incidence of severe disease. We suggest that future pandemic modelling may benefit from relying on 'SIR+ models': epidemiological models extended to account for the benefits of social interactions that affect immune resilience. We develop an SIR+ model and discuss which specific interventions may be more effective in balancing the trade-off between minimizing pathogen spread and maximizing other interaction-dependent health benefits. Our SIR+ model reflects the idea that health is not just the mere absence of disease, but rather a state of physical, mental and social well-being that can also be dependent on the same social connections that allow pathogen spread, and the modelling of public health interventions for future pandemics should account for this multidimensionality.

Mitochondrial morphology in the mouse adrenal cortex: Influence of chronic psychosocial stress

Mitochondria within the adrenal cortex play a key role in synthesizing steroid hormones. The adrenal cortex is organized in three functionally specialized zones (glomerulosa, fasciculata, and reticularis) that produce different classes of steroid hormones in response to various stimuli, including psychosocial stress. Given that the functions and morphology of mitochondria are dynamically related and respond to stress, we applied transmission electron microscopy (TEM) to examine potential differences in mitochondrial morphology under basal and chronic psychosocial stress conditions. We used the chronic subordinate colony housing (CSC) paradigm, a murine model of chronic psychosocial stress. Our findings quantitatively define how mitochondrial morphology differs among each of the three adrenal cortex zones under basal conditions, and show that chronic psychosocial stress mainly affected mitochondria in the zona glomerulosa, shifting their morphology towards the more typical glucocorticoid-producing zona fasciculata mitochondrial phenotype. Analysis of adrenocortical lipid droplets that provide cholesterol for steroidogenesis showed that chronic psychosocial stress altered lipid droplet diameter, without affecting droplet number or inter-organellar mitochondria-lipid droplet interactions. Together, our findings support the hypothesis that each adrenal cortex layer is characterized by morphologically distinct mitochondria and that this adrenal zone-specific mitochondrial morphology is sensitive to environmental stimuli, including chronic psychosocial stressors. Further research is needed to define the role of these stress-induced changes in mitochondrial morphology, particularly in the zona glomerulosa, on stress resilience and related behaviors.

Opioid trail: Tracking contributions to opioid use disorder from host genetics to the gut microbiome

Opioid use disorder (OUD) is a worldwide public health crisis with few effective treatment options. Traditional genetics and neuroscience approaches have provided knowledge about biological mechanisms that contribute to OUD-related phenotypes, but the complexity and magnitude of effects in the brain and body remain poorly understood. The gut-brain axis has emerged as a promising target for future therapeutics for several psychiatric conditions, so characterizing the relationship between host genetics and the gut microbiome in the context of OUD will be essential for development of novel treatments. In this review, we describe evidence that interactions between host genetics, the gut microbiome, and immune signaling likely play a key role in mediating opioid-related phenotypes. Studies in humans and model organisms consistently demonstrated that genetic background is a major determinant of gut microbiome composition. Furthermore, the gut microbiome is susceptible to environmental influences such as opioid exposure. Additional work focused on gene by microbiome interactions will be necessary to gain improved understanding of their effects on OUD-related behaviors.

The Many Hosts of Mycobacteria 9 (MHM9): A conference report

The Many Hosts of Mycobacteria (MHM) meeting series brings together basic scientists, clinicians and veterinarians to promote robust discussion and dissemination of recent advances in our knowledge of numerous mycobacterial diseases, including human and bovine tuberculosis (TB), nontuberculous mycobacteria (NTM) infection, Hansen's disease (leprosy), Buruli ulcer and Johne's disease. The 9th MHM conference (MHM9) was held in July 2022 at The Ohio State University (OSU) and centered around the theme of "Confounders of Mycobacterial Disease." Confounders can and often do drive the transmission of mycobacterial diseases, as well as impact surveillance and treatment outcomes. Various confounders were presented and discussed at MHM9 including those that originate from the host (comorbidities and coinfections) as well as those arising from the environment (e.g., zoonotic exposures), economic inequality (e.g. healthcare disparities), stigma (a confounder of leprosy and TB for millennia), and historical neglect (a confounder in Native American Nations). This conference report summarizes select talks given at MHM9 highlighting recent research advances, as well as talks regarding the historic and ongoing impact of TB and other infectious diseases on Native American Nations, including those in Southwestern Alaska where the regional TB incidence rate is among the highest in the Western hemisphere.

Subcutaneous Mycobacterium vaccae ameliorates the effects of early life adversity alone or in combination with chronic stress during adulthood in male and female mice

Chronic psychosocial stress is a burden of modern society and poses a clear risk factor for a plethora of somatic and affective disorders, of which most are associated with an activated immune status and chronic low-grade inflammation. Preclinical and clinical studies further suggest that a failure in immunoregulation promotes an over-reaction of the inflammatory stress response and, thus, predisposes an individual to the development of stress-related disorders. Therefore, all genetic (i.e., sex) and environmental (i.e., early life adversity; ELA) factors facilitating an adult's inflammatory stress response are likely to increase their stress vulnerability. In the present study we investigated whether repeated subcutaneous (s.c.) administrations with a heat-killed preparation of Mycobacterium vaccae (M. vaccae; National Collection of Type Cultures (NCTC) 11659), an abundant soil saprophyte with immunoregulatory properties, are protective against negative behavioral, immunological and physiological consequences of ELA alone or of ELA followed by chronic psychosocial stress during adulthood (CAS) in male and female mice. ELA was induced by the maternal separation (MS) paradigm, CAS was induced by 19 days of chronic subordinate colony housing (CSC) in males and by a 7-week exposure to the social instability paradigm (SIP) in females. Our data indicate that ELA effects in both sexes, although relatively mild, were to a great extent prevented by subsequent s.c. M. vaccae administrations. Moreover, although the use of different paradigms for males and females impedes a direct comparison, male mice seemed to be more susceptible to CAS than females, with only females benefitting slightly from the stress protective effects of s.c. M. vaccae administrations when given prior to CAS alone. Finally, our data support the hypothesis that female mice are more vulnerable to the additive effects of ELA and CAS than male mice and that s.c. M. vaccae administrations subsequent to ELA but prior to CAS are protective in both sexes. Taken together and considering the limitation that CAS in males and females was induced by different paradigms, our findings are consistent with the hypotheses that murine stress vulnerability during different phases of life is strongly sex dependent and that developing immunoregulatory approaches, such as repeated s.c. administrations with immunoregulatory microorganisms, have potential for prevention/treatment of stress-related disorders.

Neutrophil-derived catecholamines mediate negative stress effects on bone

Mental traumatization is associated with long-bone growth retardation, osteoporosis and increased fracture risk. We revealed earlier that mental trauma disturbs cartilage-to-bone transition during bone growth and repair in mice. Trauma increased tyrosine hydroxylase-expressing neutrophils in bone marrow and fracture callus. Here we show that tyrosine hydroxylase expression in the fracture hematoma of patients correlates positively with acknowledged stress, depression, and pain scores as well as individual ratings of healing-impairment and pain-perception post-fracture. Moreover, mice lacking tyrosine hydroxylase in myeloid cells are protected from chronic psychosocial stress-induced disturbance of bone growth and healing. Chondrocyte-specific β2-adrenoceptor-deficient mice are also protected from stress-induced bone growth retardation. In summary, our preclinical data identify locally secreted catecholamines in concert with β2-adrenoceptor signalling in chondrocytes as mediators of negative stress effects on bone growth and repair. Given our clinical data, these mechanistic insights seem to be of strong translational relevance.

A fatal alliance: Glial connexins, myelin pathology and mental disorders

Mature oligodendrocytes are myelin forming glial cells which are responsible for myelination of neuronal axons in the white matter of the central nervous system. Myelin pathology is a major feature of severe neurological disorders. Oligodendrocyte-specific gene mutations and/or white matter alterations have also been addressed in a variety of mental disorders. Breakdown of myelin integrity and demyelination is associated with severe symptoms, including impairments in motor coordination, breathing, dysarthria, perception (vision and hearing), and cognition. Furthermore, there is evidence indicating that myelin sheath defects and white matter pathology contributes to the affective and cognitive symptoms of patients with mental disorders. Oligodendrocytes express the connexins GJC2; mCx47 [human (GJC2) and mouse (mCx47) connexin gene nomenclature according to Söhl and Willecke (2003)], GJB1; mCx32, and GJD1; mCx29 in both white and gray matter. Preclinical findings indicate that alterations in connexin expression in oligodendrocytes and astrocytes can induce myelin defects. GJC2; mCx47 is expressed at early embryonic stages in oligodendrocyte precursors cells which precedes central nervous system myelination. In adult humans and animals GJC2, respectively mCx47 expression is essential for oligodendrocyte function and ensures adequate myelination as well as myelin maintenance in the central nervous system. In the past decade, evidence has accumulated suggesting that mental disorders can be accompanied by changes in connexin expression, myelin sheath defects and corresponding white matter alterations. This dual pathology could compromise inter-neuronal information transfer, processing and communication and eventually contribute to behavioral, sensory-motor, affective and cognitive symptoms in patients with mental disorders. The induction of myelin repair and remyelination in the central nervous system of patients with mental disorders could help to restore normal neuronal information propagation and ameliorate behavioral and cognitive symptoms in individuals with mental disorders.

DHEAS and nutritional status among Sidama, Ngandu, and Aka children: Effects of cortisol and implications for adrenarche

OBJECTIVE

Adrenarche, the biological event marked by rising production of dehydroepiandrosterone and its sulfate (DHEAS), may represent a sensitive period in child development, with important implications for adolescence and beyond. Nutritional status, particularly BMI and/or adiposity, has long been hypothesized as a factor in DHEAS production but findings are inconsistent, and few studies have examined this among non-industrialized societies. In addition, cortisol has not been included in these models. We here evaluate effects of height- (HAZ), weight- (WAZ), and BMI- (BMIZ) for-age on DHEAS concentrations among Sidama agropastoralist, Ngandu horticulturalist, and Aka hunter-gatherer children.

METHODS

Heights and weights were collected from 206 children aged 2-18 years old. HAZ, WAZ, and BMIZ were calculated using CDC standards. DHEAS and cortisol assays were used to determine biomarker concentrations in hair. Generalized linear modeling was used to examine effects of nutritional status on DHEAS concentrations, as well as cortisol, controlling for age, sex, and population.

RESULTS

Despite the prevalence of low HAZ and WAZ scores, the majority (77%) of children had BMI z-scores >-2.0 SD. Nutritional status has no significant effect on DHEAS concentrations, controlling for age, sex, and population. Cortisol, however, is a significant predictor of DHEAS concentrations.

CONCLUSIONS

Our findings do not support a relationship between nutritional status and DHEAS. Instead, results suggest an important role for stress and ecology in DHEAS concentrations across childhood. Specifically, effects of environment via cortisol may be influential to patterning of DHEAS. Future work should investigate local ecological stressors and their relationship to adrenarche.

Association of pro-inflammatory cytokines with trauma and post-traumatic stress disorder visiting a tertiary care hospital in Kathmandu

Post-traumatic stress disorder (PTSD) is a mental disorder that can occur after trauma. Although inflammatory markers such as cytokines are found altered in trauma and PTSD, there is no consensus regarding which can be considered as biomarkers. Studies from South Asia region is also rare. We studied cytokines among trauma affected patients and matched healthy controls. Fifty patients (cases) with trauma, visiting the University hospital in Kathmandu and thirty-nine healthy controls were selected, and the levels of cytokines were determined using a Luminex IS 200. We compared the levels of the cytokines in thirty-four age and gender matched pairs of case and control among three groups: healthy volunteers, cases diagnosed as PTSD, and cases without PTSD. Among the 34 pair-matched cases and controls, IL-6 was significantly higher in both PTSD positive cases [2.43 (0.00-14.54) pg/ml; p = 0.004] and PTSD negative cases [3.00 (0.92-3.86) pg/ml; p = 0.005], than in controls [0.39 (0.00-11.38) pg/ml]. IL-1β was significantly higher in PTSD positive cases [0.17 (0.00-5.27) pg/ml; p = 0.011] than in controls 0.00 (0.00-0.12) pg/ml. Other cytokines did not show significant differences. IL-6 was higher in both the trauma affected groups and IL-1β was higher in the trauma affected group with PTSD when compared to healthy controls. This supports the immune system activation hypothesis after trauma.

Explanatory integration and integrated explanations in Darwinian medicine and evolutionary medicine

Recently, two research traditions that bring together evolutionary biology and medicine, that is to say, Darwinian medicine and evolutionary medicine, have been identified. In this paper, I analyse these two research traditions with respect to explanatory and interdisciplinary integration. My analysis shows that Darwinian medicine does not integrate medicine and evolutionary biology in any strong sense but does incorporate evolutionary concepts into medicine. I also show that backward-looking explanations in Darwinian medicine are not integrated proximate-and-ultimate explanations but functional explanations that include reference to evolutionary concepts. Nevertheless, explanations in Darwinian medicine have heuristic roles as they potentially contribute to conceptual change and tie pieces of knowledge from different fields of medical research together. I argue that Darwinian medicine is an "interfield" that fosters cross-disciplinary exchange between evolutionary biologists and medical researchers and practitioners based on division of labour and separation, rather than unity. Research in evolutionary medicine, on the other hand, happens at the intersection of evolutionary biology and medicine where the two disciplines are already integrated and is designed to produce entangled proximate-evolutionary explanations. My analysis thus adds another important aspect to the philosophical discussion on the distinction between Darwinian medicine and evolutionary medicine.

Long-Term Effects of Mountain Hiking vs. Forest Therapy on Physical and Mental Health of Couples: A Randomized Controlled Trial

BACKGROUND

Lifelong physical activity is related to longer health span, which is reflected at an individual level, and is of substantial socioeconomic relevance. Sedentary lifestyles, on the other hand, pose an increasingly major public health problem. In addition, the COVID-19 pandemic had a negative impact on activity levels and well-being. Previous research indicates that contact with nature might improve exercise levels as well as well-being.

METHODS

This randomized, controlled clinical trial (ANKER-study) investigated the effects of two types of nature-based therapies (forest therapy and mountain hiking) in couples (FTG: n = 23; HG: n = 22;) with a sedentary or inactive lifestyle on health-related quality of life, relationship quality and other psychological and physiological parameters.

RESULTS

The results of this study displayed that healthy and highly functioning women and men with sedentary lifestyles mentally benefit from contact with nature (quality of life, satisfaction with life, mood, internal and external health-related control beliefs). The gender-specific effect on women is most visible in the physiological outcomes (hemopoietic system, aerobic capacity, skeletal muscle mass and hydration) of mountain hiking. Men and women showed small improvements in blood pressure as a result of the interventions.

CONCLUSIONS

The ANKER-study provides a method for valid comparison of forest therapy interventions for the first time. Regarding the COVID-19 pandemic, the nature-based intervention presented could offer a multimodal contribution to maintaining a more active lifestyle, further contact with nature that affects peoples physical as well as mental health, and an improvement in social interaction.

Changes in the Serum Concentration Levels of Serotonin, Tryptophan and Cortisol among Stress-Resilient and Stress-Susceptible Individuals after Experiencing Traumatic Stress

BACKGROUND

Stress is a common response to many environmental adversities. However, once dysregulated, this reaction can lead to psychiatric illnesses, such as post-traumatic stress disorder (PTSD). Individuals can develop PTSD after exposure to traumatic events, severely affecting their quality of life. Nevertheless, not all individuals exposed to stress will develop psychiatric disorders, provided they show enhanced stress-resilience mechanisms that enable them to successfully adapt to stressful situations and thus avoid developing a persistent psychopathology.

METHODS

The study involved 93 participants. Of them, 62 comprised a study group and 31 comprised a control group. The aim of the study was to assess serotonin, cortisol and tryptophan concentration levels in subjects with PTSD (stress-susceptible; PTSD-SS) and in healthy individuals (stress-resilient; PTSD-SR), who had experienced a traumatic event but fully recovered after the trauma. The subjects were between 18 and 50 years of age (mean 35.56 ± 8.26 years). The serum concentration levels of serotonin, cortisol and tryptophan were measured with an ELISA kit.

RESULTS

It was found that the serotonin, tryptophan and cortisol concentration levels were consistent with the features of both PTSD-SR and PTSD-SS patients. It was reported that the mean cortisol concentration levels increased more significantly in the PTSD-SS group than in the PTSD-SR group, versus those in the control group. Similarly, the PTSD-SS group was found to show a larger decrease in the mean serotonin concentration levels than the PTSD-SR group, versus those in the control group. No significant changes were found in the tryptophan concentration levels between the study groups, versus those in the control group.

CONCLUSIONS

These findings can be useful when attempting to improve resilience in individuals using neuropharmacological methods. However, it is necessary to conduct more cross-sectional studies that would address different types of negative stress to find out whether they share common pathways.

Investigating the impact of distinct contemplative mental trainings on daily life stress, thoughts and affect-Evidence from a nine-month longitudinal ecological momentary assessment study

Mindfulness-based mental training interventions have become a popular means to alleviate stress and stress-associated health risks. Previous scientific investigations emphasize the importance of exploring the effects of such interventions in naturalistic settings to evaluate their implementation into daily life. Therefore, the current study examined the effects of three distinct mental training modules on a range of measures of daily life experience in the scope of the ReSource Project, a 9-month longitudinal mental training study comparing modules targeting attention and interoception (Presence), socio-affective (Affect) or socio-cognitive abilities (Perspective). We used ecological momentary assessment (EMA) to repeatedly probe levels of stress and stress-coping efficacy combined with stress-reactive cortisol levels, and further explored arousal, affective states, and thought patterns in the daily lives of 289 healthy adults (172 women; 20-55 years). We found increased presence-focused thought and heightened arousal after a training duration of 3-6 months, independent of the type of prior training. Increased coping efficacy emerged specifically after socio-cognitive Perspective training, following 6-9 months of training duration. No training effects were found for subjective stress, stress-reactive cortisol levels, or daily life affect. Our findings corroborate and add ecological validity to previous ReSource findings by showing that they replicate in participants' everyday environment. Regarding endocrine and subjective stress markers, our results suggest caution in generalizing acute laboratory findings to individuals' everyday routines. Overall, the current study provides substantiated insights into how cultivating one's mind through contemplative mental training translates to daily life experience, enhances stress-coping, and may ultimately aide in maintaining health.

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.

Brain-body responses to chronic stress: a brief review

In order to survive and thrive, organisms must adapt to constantly changing environmental pressures. When there are significant shifts in the environment, the brain and body engage a set of physiological and behavioral countermeasures collectively known as the "stress response". These responses, which include changes at the cellular, systems, and organismal level, are geared toward protecting homeostasis and adapting physiological operating parameters so as to enable the organism to overcome short-term challenges. It is the shift of these well-organized acute responses to dysregulated chronic responses that leads to pathologies. In a sense, the protective measures become destructive, causing the myriad health problems that are associated with chronic stress. To further complicate the situation, these challenges need not be purely physical in nature. Indeed, psychosocial stressors such as ruminating about challenges at work, resource insecurity, and unstable social environments can engage the very same emergency threat systems and eventually lead to the same types of pathologies that sometimes are described as "burnout" in humans. This short review focuses on very recent empirical work exploring the effects of chronic stress on key brain circuits, metabolism and metabolic function, and immune function.

Signs of Dissociation and Symptoms of Post-Traumatic Stress Disorder in Inflammatory Bowel Disease: A Case-Control Study

BACKGROUND

Several psychological disorders have been described in patients affected by inflammatory bowel disease (IBD). Few studies have focused on the relationship between IBD and post-traumatic stress disorder (PTSD) symptoms, and no data are available on the relationship between IBD and dissociative symptoms. The aim of the present study was to evaluate the prevalence of PTSD and dissociative symptoms in a sample of IBD patients compared to healthy controls. A possible relationship with disease activity was also investigated.

METHODS

A total of 112 IBD patients, 55 Crohn's disease (CD) and 57 ulcerative colitis (UC), and 114 healthy individuals were evaluated. IBD patients were divided into 3 subgroups according to disease activity (remission, mild, and moderate). The revised version of the Impact of Event Scale (IES-R) and the Dissociative Experience Scale (DES) were administered to patients and controls.

RESULTS

IBD patients showed significantly higher rates of PTSD and dissociative symptoms compared to healthy controls. No differences were found between CD and UC patients. PTSD and dissociative symptoms were higher among CD patients with mild to moderate-severe activity compared to the remission group. No differences were found among UC patients with different activity levels.

CONCLUSION

IBD patients show a high prevalence of dissociative and traumatic affective disorders. Future studies are needed to investigate the role of these disorders in the clinical course and management of IBD patients according to the different disease activity phase.

Rapidly Growing Mycobacterium Species: The Long and Winding Road from Tuberculosis Vaccines to Potent Stress-Resilience Agents

Inflammatory diseases and stressor-related psychiatric disorders, for which inflammation is a risk factor, are increasing in modern Western societies. Recent studies suggest that immunoregulatory approaches are a promising tool in reducing the risk of suffering from such disorders. Specifically, the environmental saprophyte Mycobacterium vaccae National Collection of Type Cultures (NCTC) 11659 has recently gained attention for the prevention and treatment of stress-related psychiatric disorders. However, effective use requires a sophisticated understanding of the effects of M. vaccae NCTC 11659 and related rapidly growing mycobacteria (RGMs) on microbiome–gut–immune–brain interactions. This historical narrative review is intended as a first step in exploring these mechanisms and provides an overview of preclinical and clinical studies on M. vaccae NCTC 11659 and related RGMs. The overall objective of this review article is to increase the comprehension of, and interest in, the mechanisms through which M. vaccae NCTC 11659 and related RGMs promote stress resilience, with the intention of fostering novel clinical strategies for the prevention and treatment of stressor-related disorders.

Kefir ameliorates specific microbiota-gut-brain axis impairments in a mouse model relevant to autism spectrum disorder

Autism spectrum disorder (ASD) is one of the most severe developmental disorders, affecting on average 1 in 150 children worldwide. There is a great need for more effective strategies to improve quality of life in ASD subjects. The gut microbiome has emerged as a potential therapeutic target in ASD. A novel modulator of the gut microbiome, the traditionally fermented milk drink kefir, has recently been shown to modulate the microbiota and decrease repetitive behaviour, one of the hallmarks of ASD, in mice. As such, we hypothesized that kefir could ameliorate behavioural deficits in a mouse model relevant to ASD; the BTBR T⁺ Itpr3^tf/J mouse strain. To this end, adult mice were administered either kefir (UK4) or a milk control for three weeks as treatment lead-in, after which they were assessed for their behavioural phenotype using a battery of tests. In addition, we assessed systemic immunity by flow cytometry and the gut microbiome using shotgun metagenomic sequencing. We found that indeed kefir decreased repetitive behaviour in this mouse model. Furthermore, kefir prolonged stress-induced increases in corticosterone 60 min post-stress, which was accompanied by an ameliorated innate immune response as measured by LY6C^hi monocyte levels. In addition, kefir increased the levels of anti-inflammatory Treg cells in mesenteric lymph nodes (MLNs). Kefir also increased the relative abundance of Lachnospiraceae bacterium A2, which correlated with reduced repetitive behaviour and increased Treg cells in MLNs. Functionally, kefir modulated various predicted gut microbial pathways, including the gut-brain module S-Adenosylmethionine (SAM) synthesis, as well as L-valine biosynthesis and pyruvate fermentation to isobutanol, which all correlated with repetitive behaviour. Taken together our data show that kefir modulates peripheral immunoregulation, can ameliorate specific ASD behavioural dysfunctions and modulates selective aspects of the composition and function of the gut microbiome, indicating that kefir supplementation might prove a viable strategy in improving quality of life in ASD subjects.

Low-grade systemic inflammation and the workplace

BACKGROUND

Psychosocial and physical stressors can elicit the stress response, co-ordinated by interactions between neuroendocrine and inflammatory processes. The central role of the immune system, specifically low-grade systemic inflammation, is sometimes overlooked in work-related stress research.

OBJECTIVE

To review evidence that work-related psychosocial and physical stressors can stimulate a low-grade systemic inflammation which, through interactions with the neurohormonal systems, may impact on the well-being and productivity of workers.

METHODS

Literature searches were performed by databases and by hand. Databases used included Interface - EBSCOhost Research Databases; PsycINFO; Academic Search Complete; Africa-Wide Information; CINAHL; E-Journals; MEDLINE and PsycARTICLES.

RESULTS

Psychosocial stressors, infections, poor indoor air quality, musculoskeletal injuries and chemicals can stimulate a low-grade systemic inflammation that may adversely affect workers' mental and physical health, as well as productivity. The psychological and physical effects caused by infection-induced inflammation are generally referred to as sickness behaviour and those caused by poor indoor air quality as sick building syndrome.

CONCLUSIONS

Stressor-induced low-grade systemic inflammation can be a causal factor in the physical and behavioural symptoms of work-related stress. It is therefore important that those involved with the health of workers be cognisant of inappropriate or chronic low-grade inflammation as a potential health hazard.

Acute stress increases monocyte levels and modulates receptor expression in healthy females

There has been a growing recognition of the involvement of the immune system in stress-related disorders. Acute stress leads to the activation of neuroendocrine systems, which in turn orchestrate a large-scale redistribution of innate immune cells, such as monocytes. Even though acute stress/monocyte interactions have been well-characterized in mice, this is not the case for humans. As such, this study aimed to investigate whether acute stress modulates blood monocyte levels in a subtype-dependent manner and whether the receptor expression of stress-related receptors is affected in humans. Blood was collected from healthy female volunteers at baseline and 1 h after the socially evaluated cold pressor test, after which blood monocyte levels and receptor expression were assessed by flow cytometry. Our results reveal a stress-induced increase in blood monocyte levels, which was independent of monocyte subtypes. Furthermore, colony stimulating factor 1 receptor (CSF-1R) and CD29 receptor expression was increased, while CD62L showed a trend towards increased expression. These results provide novel insights into how acute stress affects the innate immune system.

The Hygiene Hypothesis and New Perspectives-Current Challenges Meeting an Old Postulate

During its 30 years history, the Hygiene Hypothesis has shown itself to be adaptable whenever it has been challenged by new scientific developments and this is a still a continuously ongoing process. In this regard, the mini review aims to discuss some selected new developments in relation to their impact on further fine-tuning and expansion of the Hygiene Hypothesis. This will include the role of recently discovered classes of innate and adaptive immune cells that challenges the old Th1/Th2 paradigm, the applicability of the Hygiene Hypothesis to newly identified allergy/asthma phenotypes with diverse underlying pathomechanistic endotypes, and the increasing knowledge derived from epigenetic studies that leads to better understanding of mechanisms involved in the translation of environmental impacts on biological systems. Further, we discuss in brief the expansion of the Hygiene Hypothesis to other disease areas like psychiatric disorders and cancer and conclude that the continuously developing Hygiene Hypothesis may provide a more generalized explanation for health burden in highly industrialized countries also relation to global changes.

Promotion of Para athlete well-being in South Africa (the PROPEL studies): Profiles and prevalence of psychological distress

OBJECTIVES

There is a paucity of research investigating mental health in Para athletes. The aim of this study was to describe mental health concerns of a representative sample of South African Para athletes.

DESIGN

A descriptive, cross-sectional survey was conducted at the 2019 National Championships for athletes with impairments.

METHODS

Mental health was measured with the Trait component of the State/Trait Anxiety Inventory (STAI-T), and the Kessler Psychological Distress Scale (K-10). Between-group differences were analysed using the Mann-Whitney U test or one-way ANOVA.

RESULTS

A total of 125 athletes were included. The average score for the STAI-T was 39 (±9) units, whilst a quarter (25%) of all athletes scored ≥45. The mean K-10 questionnaire score was 20 (±6) units. K-10 scores indicated that 12 % of athletes may meet formal definitions for anxiety and/or depressive disorders (score of ≥28), while 76 % of athletes have a high level of subclinical symptoms (score of ≥16). On average, females (36 ± 9) had better STAI-T scores than males (40 ± 9; p = 0.02) and married athletes (33 ± 9) had better scores than unmarried athletes (40 ± 9; p = 0.002). K-10 scores were also significantly better in married than in unmarried athletes (p = 0.002), but there was no difference between sexes. Neither the K-10 nor STAI-T was associated with level of competition, sport code or impairment type.

CONCLUSIONS

The study identified a high prevalence of psychological distress and anxiety among South African Para athletes, compared to the general population. There is a need to further understand factors contributing to mental health in this population.

Comparing the effects of two different strains of mycobacteria, Mycobacterium vaccae NCTC 11659 and M. vaccae ATCC 15483, on stress-resilient behaviors and lipid-immune signaling in rats

Stress-related disorders, such as posttraumatic stress disorder (PTSD), are highly prevalent and often difficult to treat. In rodents, stress-related, anxiety-like defensive behavioral responses may be characterized by social avoidance, exacerbated inflammation, and altered metabolic states. We have previously shown that, in rodents, subcutaneous injections of a heat-killed preparation of the soil-derived bacterium Mycobacterium vaccae NCTC 11659 promotes stress resilience effects that are associated with immunoregulatory signaling in the periphery and the brain. In the current study, we sought to determine whether treatment with a heat-killed preparation of the closely related M. vaccae type strain, M. vaccae ATCC 15483, would also promote stress-resilience in adult male rats, likely due to biologically similar characteristics of the two strains. Here we show that immunization with either M. vaccae NCTC 11659 or M. vaccae ATCC 15483 prevents stress-induced increases in hippocampal interleukin 6 mRNA expression, consistent with previous studies showing that M. vaccae NCTC 11659 prevents stress-induced increases in peripheral IL-6 secretion, and prevents exaggeration of anxiety-like defensive behavioral responses assessed 24 h after exposure to inescapable tail shock stress (IS) in adult male rats. Analysis of mRNA expression, protein abundance, and flow cytometry data demonstrate overlapping but also unique effects of treatment with the two M. vaccae strains on immunological and metabolic signaling in the host. These data support the hypothesis that treatment with different M. vaccae strains may immunize the host against stress-induced dysregulation of physiology and behavior.

An analysis of mother stress before and during COVID-19 pandemic: The case of China

In this study, the authors aimed to examine relations between mothers' stress (PSI-SF) and their children during the COVID-19 pandemic confinement in mainland China (N  = 274; mean age = 32.95, SD = 5.59). Our analyses revealed mothers identified more stress problems during the confinement than before including Difficult Child, Parental Distress, and Parent-Child Dysfunctional Interaction, which predicted requests for clinical or parents support services. Mothers living in rural areas reported less stress. Single mothers and those in small households displayed a higher level of stress. Our research results may assist policymakers, professionals, and researchers to design support needed to promote families' psychological well-being.

Inducing a stressed phenotype in healthy recipient mice by adoptively transferring CD4+ lymphocytes from mice undergoing chronic psychosocial stress

Although chronic stress is an acknowledged risk factor for the development of somatic and affective disorders, the cellular and molecular mechanisms underlying stress-induced pathologies are not fully understood. Interestingly, rodent studies involving immune cell transfer suggest that CD4⁺ T cells might be at least in part involved in reactivation of a chemically-induced colitis by stress. However, until now evidence is lacking that these immune cell types are indeed involved in the development of a "stressed phenotype". The aim of the present study was, therefore, to assess the effects of adoptively transferring total mesenteric lymph node cells (mesLNCs) and CD4⁺ mesLNCs isolated from chronically-stressed mice into healthy recipient mice on various physiological, immunological and behavioral parameters. To induce chronic psychosocial stress in donor mice we employed the chronic subordinate colony housing (CSC) paradigm. Our data indicate that transfer of total or CD4⁺ mesLNCs from CSC mice, compared with respective cells from single-housed control (SHC) mice, promoted splenomegaly and interferon (IFN)-γ secretion from in vitro anti-CD3-stimulated mesLNCs in naïve recipient mice. This effect was independent of recipient mice additionally being administered with dextran sulfate sodium (DSS) or not. Transfer of CD4⁺ mesLNCs additionally increased adrenal weight and secretion of IL-6 from in vitro anti-CD3 stimulated mesLNCs in recipients administered with DSS. Importantly, transfer of neither cell type from CSC vs. SHC donor mice affected anxiety-related behavior of recipient mice in the light-dark box. Taken together, our data demonstrate that typical physiological and immunological, but not behavioral, effects of chronic stress can be induced in naïve recipient mice by adoptively transferring mesLNCs, in particular CD4⁺ mesLNCs, from chronically stressed donor mice.

Gut Feelings: How Microbiota Might Impact the Development and Course of Anorexia Nervosa

Anorexia nervosa (AN) can probably be regarded as a "model" for studying the interaction of nutrition with the gut-brain axis, which has drawn increased attention from researchers and clinicians alike. The gut microbiota influences somatic effects, such as energy extraction from food and body weight gain, as well as appetite, gut permeability, inflammation and complex psychological behaviors, such as depression or anxiety, all of which play important roles in AN. As nutrition is one of the main factors that influence the gut microbiota, nutritional restriction and selective eating in AN are likely influencing factors; however, nutritional rehabilitation therapy is surprisingly understudied. Here, we review the general mechanisms of the interactions between nutrition, the gut microbiota and the host that may be relevant to AN, paying special attention to the gut-brain axis, and we present the first specific findings in patients with AN and corresponding animal models. In particular, nutritional interventions, including food selection, supplements, and pre-, pro- and synbiotics that have the potential to influence the gut microbiota, are important research targets to potentially support future AN therapy.

Alzheimer's Disease: Protective Effects of Mycobacterium vaccae, a Soil-Derived Mycobacterium with Anti-Inflammatory and Anti-Tubercular Properties, on the Proteomic Profiles of Plasma and Cerebrospinal Fluid in Rats

BACKGROUND

Alzheimer's disease (AD) is an inflammatory neurodegenerative disease that may be associated with prior bacterial infections. Microbial "old friends" can suppress exaggerated inflammation in response to disease-causing infections or increase clearance of pathogens such as Mycobacterium tuberculosis, which causes tuberculosis (TB). One such "old friend" is Mycobacterium vaccae NCTC 11659, a soil-derived bacterium that has been proposed either as a vaccine for prevention of TB, or as immunotherapy for the treatment of TB when used alongside first line anti-TB drug treatment.

OBJECTIVE

The goal of this study was to use a hypothesis generating approach to explore the effects of M. vaccae on physiological changes in the plasma and cerebrospinal fluid (CSF).

METHODS

Liquid chromatography-tandem mass spectrometry-based proteomics were performed in plasma and CSF of adult male rats after immunization with a heat-killed preparation of M. vaccae NCTC 11659 or borate-buffered saline vehicle. Gene enrichment analysis and analysis of protein-protein interactions were performed to integrate physiological network changes in plasma and CSF. We used RT-qPCR to assess immune and metabolic gene expression changes in the hippocampus.

RESULTS

In both plasma and CSF, immunization with M. vaccae increased proteins associated with immune activation and downregulated proteins corresponding to lipid (including phospholipid and cholesterol) metabolism. Immunization with M. vaccae also increased hippocampal expression of interleukin-4 (IL-4) mRNA, implicating anti-inflammatory effects in the central nervous system.

CONCLUSION

M. vaccae alters host immune activity and lipid metabolism. These data are consistent with the hypothesis that microbe-host interactions may protect against possible infection-induced, inflammation-related cognitive impairments.

Bioactive Polyphenols from Pomegranate Juice Reduce 5-Fluorouracil-Induced Intestinal Mucositis in Intestinal Epithelial Cells

Intestinal epithelial cells (IECs) play a pivotal role in maintaining intestinal homeostasis. Different noxious agents, among them also anticancer therapies, can impair intestinal epithelial integrity triggering inflammation and oxidative stress. A frequent complication of chemotherapy is gastrointestinal mucositis, strongly influencing the effectiveness of therapy, increasing healthcare costs, and impairing patients’ quality of life. Different strategies are used to treat gastrointestinal mucositis, including products from natural sources. Our study focused on the effect of pomegranate (Punica granatum L.) juice extract on IEC-6 cells, both during inflammatory conditions and following treatment with 5-fluorouracil (5-FU). The polyphenolic profile of pomegranate juice was characterized in detail by Online Comprehensive two dimensional Liquid Chromatography-Mass Spectrometry. The evaluation of pomegranate juice extract in IEC-6 indicates a significant inhibition in proinflammatory factors, such as cytokines release, cyclooxygenase-2 and inducible nitric oxide synthase expression, and nitrotyrosine formation. Pomegranate also inhibited oxidative stress and adhesion protein expression. In 5-FU-treated IEC-6, pomegranate also inhibited both inflammatory and oxidative stress parameters and apoptosis. It promoted wound repair and tight junction expression. These results suggest a potential use of pomegranate as an adjuvant in the treatment of intestinal inflammatory and oxidative stress states, which also occur during chemotherapy-induced mucositis.

Pro-inflammatory markers and fatigue in patients with depression: A case-control study

The aim of this work was to investigate differences between depressed subjects (PG) and non-depressed healthy control participants (HCG) with regard to fatigue dimensions and inflammation. For this purpose, 43 participants in the PG and 51 participants in the HCG were included in the study. IL-6, IL-1β, TNF-α, IFN-γ, and CRP were assessed in venous blood samples. Fatigue and depression were assessed using the FIS-D and BDI-FS questionnaires. Main results showed higher BDI-FS values in PG. Moreover, PG showed mean differences for fatigue dimensions when compared to the HCG. For the pro-inflammatory markers, a moderate group effect was found between PG and HCG which was mainly caused by IL-6. Correlations between TNF-α and BDI-FS, TNF-α and cognitive fatigue, TNF-α and psychosocial fatigue were found within the PG. In the HCG, correlations were found between IL-6, TNF-α and somatic fatigue, as well as IL-6 and cognitive fatigue. Significant correlations were found between the psychological variables in both groups. All results were controlled for the confounding variables gender, age, BMI and multiple comparisons. These results suggest the presence of inflammation in both depression and fatigue. However, each correlates with different pro-inflammatory parameters, suggesting a biological heterogeneity.

Finding intestinal fortitude: Integrating the microbiome into a holistic view of depression mechanisms, treatment, and resilience

Depression affects at least 322 million people globally, or approximately 4.4% of the world's population. While the earnestness of researchers and clinicians to understand and treat depression is not waning, the number of individuals suffering from depression continues to increase over and above the rate of global population growth. There is a sincere need for a paradigm shift. Research in the past decade is beginning to take a more holistic approach to understanding depression etiology and treatment, integrating multiple body systems into whole-body conceptualizations of this mental health affliction. Evidence supports the hypothesis that the gut microbiome, or the collective trillions of microbes inhabiting the gastrointestinal tract, is an important factor determining both the risk of development of depression and persistence of depressive symptoms. This review discusses recent advances in both rodent and human research that explore bidirectional communication between the gut microbiome and the immune, endocrine, and central nervous systems implicated in the etiology and pathophysiology of depression. Through interactions with circulating inflammatory markers and hormones, afferent and efferent neural systems, and other, more niche, pathways, the gut microbiome can affect behavior to facilitate the development of depression, exacerbate current symptoms, or contribute to treatment and resilience. While the challenge of depression may be the direst mental health crisis of our age, new discoveries in the gut microbiome, when integrated into a holistic perspective, hold great promise for the future of positive mental health.

Association of the Salivary Microbiome With Animal Contact During Early Life and Stress-Induced Immune Activation in Healthy Participants

The prevalence of stress-associated somatic and psychiatric disorders is increased in environments offering a narrow relative to a wide range of microbial exposure. Moreover, different animal and human studies suggest that an overreactive immune system not only accompanies stress-associated disorders, but might even be causally involved in their pathogenesis. In support of this hypothesis, we recently showed that urban upbringing in the absence of daily contact with pets, compared to rural upbringing in the presence of daily contact with farm animals, is associated with a more pronounced immune activation following acute psychosocial stressor exposure induced by the Trier Social Stress Test (TSST). Here we employed 16S rRNA gene sequencing to test whether this difference in TSST-induced immune activation between urban upbringing in the absence of daily contact with pets (n = 20) compared with rural upbringing in the presence of daily contact with farm animals (n = 20) is associated with differences in the composition of the salivary microbiome. Although we did not detect any differences in alpha or beta diversity measures of the salivary microbiome between the two experimental groups, statistical analysis revealed that the salivary microbial beta diversity was significantly higher in participants with absolutely no animal contact (n = 5, urban participants) until the age of 15 compared to all other participants (n = 35) reporting either daily contact with farm animals (n = 20, rural participants) or occasional pet contact (n = 15, urban participants). Interestingly, when comparing these urban participants with absolutely no pet contact to the remaining urban participants with occasional pet contact, the former also displayed a significantly higher immune, but not hypothalamic-pituitary-adrenal (HPA) axis or sympathetic nervous system (SNS) activation, following TSST exposure. In summary, we conclude that only urban upbringing with absolutely no animal contact had long-lasting effects on the composition of the salivary microbiome and potentiates the negative consequences of urban upbringing on stress-induced immune activation.

Modelling resilience in adolescence and adversity: a novel framework to inform research and practice

Recent conceptualisations of resilience have advanced the notion that it is a dynamic and multifaceted construct. However, its adaptive components, especially those forged by adversity, have not been fully realised, and its neurobiological and psychosocial underpinnings are yet to be meaningfully integrated. In part, this is because a developmental perspective is often neglected in the formulation of resilience. In this review, we consider the findings of resilience research, with a specific emphasis on the developmental period of adolescence. To bridge the gaps in our current understanding, we propose a model of resilience that is predicated on experiencing adversity. Specifically, our model provides a sophisticated insight into the components of resilience, which, together with intrinsic features, involves facilitation of, and skill acquisition via strengthening processes we term tempering and fortification. The model also points to the potential trajectories of adversity-driven resilience and forms the basis of a framework that allows for individual variance in resilience, and the identification of both neurobiological and psychosocial targets for prevention and therapeutic interventions.

Treatment with a heat-killed preparation of Mycobacterium vaccae after fear conditioning enhances fear extinction in the fear-potentiated startle paradigm

The hygiene hypothesis or "Old Friends" hypothesis proposes that inflammatory diseases are increasing in modern urban societies, due in part to reduced exposure to microorganisms that drive immunoregulatory circuits and a failure to terminate inappropriate inflammatory responses. Inappropriate inflammation is also emerging as a risk factor for anxiety disorders, affective disorders, and trauma-and stressor-related disorders, including posttraumatic stress disorder (PTSD), which is characterized as persistent re-experiencing of the trauma after a traumatic experience. Traumatic experiences can lead to long-lasting fear memories and fear potentiation of the acoustic startle reflex. The acoustic startle reflex is an ethologically relevant reflex and can be potentiated in both humans and rats through Pavlovian conditioning. Mycobacterium vaccae is a soil-derived bacterium with immunoregulatory and anti-inflammatory properties that has been demonstrated to enhance fear extinction in the fear-potentiated startle paradigm when given prior to fear conditioning. To determine if immunization with M. vaccae after fear conditioning also has protective effects, adult male Sprague Dawley rats underwent fear conditioning on days -37 and -36 followed by immunizations (3x), once per week beginning 24 h following fear conditioning, with a heat-killed preparation of M. vaccae NCTC 11659 (0.1 mg, s.c., in 100 µl borate-buffered saline) or vehicle, and, then, 3 weeks following the final immunization, were tested in the fear-potentiated startle paradigm (n = 12 per group). Rats underwent fear extinction training on days 1 through 6 followed by spontaneous recovery 14 days later (day 20). Rats were euthanized on day 21 and brain tissue was sectioned for analysis of Tph2, Htr1a, Slc6a4, Slc22a3, and Crhr2 mRNA expression throughout the brainstem dorsal and median raphe nuclei. Immunization with M. vaccae did not affect fear expression on day 1. However, M. vaccae-immunized rats showed enhanced enhanced within-session fear extinction on day 1 and enhanced between-session fear extinction beginning on day 2, relative to vehicle-immunized controls. Immunization with M. vaccae and fear-potentiated startle had minimal effects on serotonergic gene expression when assessed 42 days after the final immunization. Together with previous studies, these data are consistent with the hypothesis that immunoregulatory strategies, such as immunization with M. vaccae, have potential for both prevention and treatment of trauma- and stressor-related psychiatric disorders.

Immune mechanisms of stress susceptibility and resilience: Lessons from animal models

Stress has an impact on the brain and the body. A growing literature demonstrates that feedback between the peripheral immune system and the brain contributes to individual differences in the behavioral response to stress. Here we examine preclinical literature to demonstrate a holistic vision of risk and resilience to stress. We identify a variety of cellular, cytokine and molecular mechanisms in adult animals that act in concert to produce a stress susceptible individual response. We discuss how cross talk between immune cells in the brain and in the periphery act together to increase permeability across the blood brain barrier or block it, resulting in susceptible or stress resilient phenotype. These preclinical studies have importance for understanding how individual differences in the immune response to stress may be contributing to mood related disorders such as depression, anxiety and posttraumatic stress disorders.

Current evidence on urbanicity and the impact of neighbourhoods on anxiety and stress-related disorders

PURPOSE OF REVIEW

To synthesize recent knowledge on the association of urbanization (and neighbourhood factors) and anxiety and stress-related disorders.

RECENT FINDINGS

The quality of urban neighbourhoods and neighbourhood factors - physical (e.g. green space), social (e.g. social cohesion) and biological (e.g. stress response) factors - are directly linked to the presence and severity of anxiety disorders, although data on posttraumatic stress disorder (PTSD) are pauce. Preliminary data indicate that architectural and space design elements in PTSD can either increase anxiety and lead to trauma triggers or relieve symptoms and reinforce safety. In addition, there is emerging evidence that being raised in urban environments with a wide range of microbial exposure dampens the immune response to psychosocial stressors.

SUMMARY

Evidence points to a higher prevalence of anxiety disorders and PTSD in urban environments. Current research is focused on the role of neighbourhood factors in prevention and treatment. Few studies have assessed comprehensive treatment models in urban populations and the potential moderating role of these factors on treatment outcomes. Several lines of inquiry are starting to address how urban living impacts on biological stress regulation pathways. As urbanization continues, improved understanding of urban mental health is central to informing mental health promotion policies.

Identification and characterization of a novel anti-inflammatory lipid isolated from Mycobacterium vaccae, a soil-derived bacterium with immunoregulatory and stress resilience properties

RATIONALE

Mycobacterium vaccae (NCTC 11659) is an environmental saprophytic bacterium with anti-inflammatory, immunoregulatory, and stress resilience properties. Previous studies have shown that whole, heat-killed preparations of M. vaccae prevent allergic airway inflammation in a murine model of allergic asthma. Recent studies also demonstrate that immunization with M. vaccae prevents stress-induced exaggeration of proinflammatory cytokine secretion from mesenteric lymph node cells stimulated ex vivo, prevents stress-induced exaggeration of chemically induced colitis in a model of inflammatory bowel disease, and prevents stress-induced anxiety-like defensive behavioral responses. Furthermore, immunization with M. vaccae induces anti-inflammatory responses in the brain and prevents stress-induced exaggeration of microglial priming. However, the molecular mechanisms underlying anti-inflammatory effects of M. vaccae are not known.

OBJECTIVES

Our objective was to identify and characterize novel anti-inflammatory molecules from M. vaccae NCTC 11659.

METHODS

We have purified and identified a unique anti-inflammatory triglyceride, 1,2,3-tri [Z-10-hexadecenoyl] glycerol, from M. vaccae and evaluated its effects in freshly isolated murine peritoneal macrophages.

RESULTS

The free fatty acid form of 1,2,3-tri [Z-10-hexadecenoyl] glycerol, 10(Z)-hexadecenoic acid, decreased lipopolysaccharide-stimulated secretion of the proinflammatory cytokine IL-6 ex vivo. Meanwhile, next-generation RNA sequencing revealed that pretreatment with 10(Z)-hexadecenoic acid upregulated genes associated with peroxisome proliferator-activated receptor alpha (PPARα) signaling in lipopolysaccharide-stimulated macrophages, in association with a broad transcriptional repression of inflammatory markers. We confirmed using luciferase-based transfection assays that 10(Z)-hexadecenoic acid activated PPARα signaling, but not PPARγ, PPARδ, or retinoic acid receptor (RAR) α signaling. The effects of 10(Z)-hexadecenoic acid on lipopolysaccharide-stimulated secretion of IL-6 were prevented by PPARα antagonists and absent in PPARα-deficient mice.

CONCLUSION

Future studies should evaluate the effects of 10(Z)-hexadecenoic acid on stress-induced exaggeration of peripheral inflammatory signaling, central neuroinflammatory signaling, and anxiety- and fear-related defensive behavioral responses.