Social stress up-regulates inflammatory gene expression in the leukocyte transcriptome via β-adrenergic induction of myelopoiesis

Genome-wide transcriptome differences associated with perceived discrimination in an urban, community-dwelling middle-aged cohort

Discrimination is a social adversity that is linked to several age-related outcomes. However, the molecular drivers of these observations are poorly understood. Social adverse factors are associated with proinflammatory and interferon gene expression, but little is known about whether additional genes are associated with discrimination among both African American and White adults. In this study, we examined how perceived discrimination in African American and White adults was associated with genome-wide transcriptome differences using RNA sequencing. Perceived discrimination was measured based on responses to self-reported lifetime discrimination and racial discrimination. Differential gene expression and pathway analysis were conducted in a cohort (N = 59) stratified by race, sex, and overall discrimination level. We found 28 significantly differentially expressed genes associated with race among those reporting high discrimination. Several of the upregulated genes for African American versus White adults reporting discrimination were related to immune function IGLV2-11, S100B, IGKV3-20, and IGKV4-1; the most significantly downregulated genes were associated with immune modulation and cancer, LUCAT1, THBS1, and ARPIN. The most enriched gene ontology biological process between African American and White men reporting high discrimination was the regulation of cytokine biosynthetic processes. The immune response biological process was significantly lower for African American women compared to White women reporting high discrimination. Discrimination was associated with the expression of small nucleolar RNAs, long noncoding RNAs, and microRNAs associated with energy homeostasis, cancer, and actin. Understanding the pathways through which adverse social factors like discrimination are associated with gene expression is crucial in advancing knowledge of age-related health disparities.

Proinflammatory gene expression is associated with prospective risk for adolescent suicidal thoughts and behaviors over twelve months

OBJECTIVE

Recent theories have implicated inflammatory biology in the development of psychopathology and maladaptive behaviors in adolescence, including suicidal thoughts and behaviors (STB). Examining specific biological markers related to inflammation is thus warranted to better understand risk for STB in adolescents, for whom suicide is a leading cause of death.

METHOD

Participants were 211 adolescent females (ages 9-14 years; Mage = 11.8 years, SD = 1.8 years) at increased risk for STB. This study examined the prospective association between basal levels of inflammatory gene expression (average of 15 proinflammatory mRNA transcripts) and subsequent risk for suicidal ideation and suicidal behavior over a 12-month follow-up period.

RESULTS

Controlling for past levels of STB, greater proinflammatory gene expression was associated with prospective risk for STB in these youth. Similar effects were observed for CD14 mRNA level, a marker of monocyte abundance within the blood sample. Sensitivity analyses controlling for other relevant covariates, including history of trauma, depressive symptoms, and STB prior to data collection, yielded similar patterns of results.

CONCLUSIONS

Upregulated inflammatory signaling in the immune system is prospectively associated with STB among at-risk adolescent females, even after controlling for history of trauma, depressive symptoms, and STB prior to data collection. Additional research is needed to identify the sources of inflammatory up-regulation in adolescents (e.g., stress psychobiology, physiological development, microbial exposures) and strategies for mitigating such effects to reduce STB.

Role of Neurotransmitters in Steady State Hematopoiesis, Aging, and Leukemia

Haematopoiesis within the bone marrow (BM) represents a complex and dynamic process intricately regulated by neural signaling pathways. This delicate orchestration is susceptible to disruption by factors such as aging, diabetes, and obesity, which can impair the BM niche and consequently affect haematopoiesis. Genetic mutations in Tet2, Dnmt3a, Asxl1, and Jak2 are known to give rise to clonal haematopoiesis of intermediate potential (CHIP), a condition linked to age-related haematological malignancies. Despite these insights, the exact roles of circadian rhythms, sphingosine-1-phosphate (S1P), stromal cell-derived factor-1 (SDF-1), sterile inflammation, and the complement cascade on various BM niche cells remain inadequately understood. Further research is needed to elucidate how BM niche cells contribute to these malignancies through neural regulation and their potential in the development of gene-corrected stem cells. This literature review describes the updated functional aspects of BM niche cells in haematopoiesis within the context of haematological malignancies, with a particular focus on neural signaling and the potential of radiomitigators in acute radiation syndrome. Additionally, it underscores the pressing need for technological advancements in stem cell-based therapies to alleviate the impacts of immunological stressors. Recent studies have illuminated the microheterogeneity and temporal stochasticity of niche cells within the BM during haematopoiesis, emphasizing the updated roles of neural signaling and immunosurveillance. The development of gene-corrected stem cells capable of producing blood, immune cells, and tissue-resident progeny is essential for combating age-related haematological malignancies and overcoming immunological challenges. This review aims to provide a comprehensive overview of these evolving insights and their implications for future therapeutic strategies.

Deleterious effects of social isolation on neuroendocrine-immune status, and cancer progression in rats

Accumulating evidence indicates that social isolation (SI) in humans and rodents is associated with increased cancer incidence and mortality, yet mediating mechanisms remain elusive. Here, we examine the neuroendocrine and immunological consequences of SI and its short- and long-term physiological impacts in naïve and cancer-bearing rats. Findings indicate that isolated animals experienced a significant decrease in weight compared to controls. Specifically, females showed a marked weight decrease during the first week of isolation. Isolated rats had significantly higher numbers of MADB106 experimental pulmonary metastases. Although mortality rates were higher in isolated tumor-bearing rats, unexpectedly, they exhibited a reduced growth rate of orthotopically implanted MADB106 tumors. Transcriptomic analyses of these excised tumors indicated a major downregulation in the expression of various genes, including those associated with pro-metastatic processes (e.g., EMT). In naïve rats (no cancer), levels of IL-6 increased, and total IgG levels decreased under SI conditions. A mixed effect was found for TNFα, which increased in females and decreased in males. In the central nervous system, isolated rats showed altered gene expression in key brain regions associated with stress responses and social behavior. The paraventricular nucleus of the thalamus emerged as a significantly affected region, along with the bed nucleus of the stria terminalis. Changes were observed in the expression of oxytocin, serotonin, and dopamine receptors. Isolated rats also exhibited greater alterations in hypothalamic-pituitary-adrenal (HPA) axis-related regulation and an increase in plasma CORT levels. Our study highlights the profound impact of SI on metastatic processes. Additionally, the potential detrimental effects of SI on thermoregulation were discussed, emphasizing the importance of social thermoregulation in maintaining physiological stability and highlighting the need to avoid single-caging practices in research. We report neuro-immune interactions and changes in brain gene expression, highlighting the need for further research into these underlying processes to improve outcomes in animal models and potential interventions for cancer patients through increased social support.

Unraveling the Role of the Blood-Brain Barrier in the Pathophysiology of Depression: Recent Advances and Future Perspectives

Depression is a highly prevalent psychological disorder characterized by persistent dysphoria, psychomotor retardation, insomnia, anhedonia, suicidal ideation, and a remarkable decrease in overall well-being. Despite the prevalence of accessible antidepressant therapies, many individuals do not achieve substantial improvement. Understanding the multifactorial pathophysiology and the heterogeneous nature of the disorder could lead the way toward better outcomes. Recent findings have elucidated the substantial impact of compromised blood-brain barrier (BBB) integrity on the manifestation of depression. BBB functions as an indispensable defense mechanism, tightly overseeing the transport of molecules from the periphery to preserve the integrity of the brain parenchyma. The dysfunction of the BBB has been implicated in a multitude of neurological disorders, and its disruption and consequent brain alterations could potentially serve as important factors in the pathogenesis and progression of depression. In this review, we extensively examine the pathophysiological relevance of the BBB and delve into the specific modifications of its components that underlie the complexities of depression. A particular focus has been placed on examining the effects of peripheral inflammation on the BBB in depression and elucidating the intricate interactions between the gut, BBB, and brain. Furthermore, this review encompasses significant updates on the assessment of BBB integrity and permeability, providing a comprehensive overview of the topic. Finally, we outline the therapeutic relevance and strategies based on BBB in depression, including COVID-19-associated BBB disruption and neuropsychiatric implications. Understanding the comprehensive pathogenic cascade of depression is crucial for shaping the trajectory of future research endeavors.

A Narrative Review on Stress and Itch: What We Know and What We Would Like to Know

Itch is one of the most prevalent symptoms experienced by patients with inflammatory skin conditions, yet it is also one of the most debilitating. Patients suffering from chronic itch have been found to have significantly higher stress levels compared with those not experiencing itch. In fact, recent studies have revealed a bidirectional relationship between stress and itch, where each condition worsens the other. This is thought to be driven by the vicious itch-scratch cycle, which is fueled by underlying inflammation. The precise molecular pathways and mediators involved, however, remain unclear. This narrative review discusses the existing research on the relationship between stress and itch and outlines future research directions that will be necessary to advance our understanding and treatment of these conditions. Given that the effective management of both symptoms often requires a combined treatment approach, further investigation into their shared mechanisms is essential for identifying successful therapies and improving patient outcomes.

Emerging insights into epigenetics and hematopoietic stem cell trafficking in age-related hematological malignancies

BACKGROUND

Hematopoiesis within the bone marrow (BM) is a complex and tightly regulated process predominantly influenced by immune factors. Aging, diabetes, and obesity are significant contributors to BM niche damage, which can alter hematopoiesis and lead to the development of clonal hematopoiesis of intermediate potential (CHIP). Genetic/epigenetic alterations during aging could influence BM niche reorganization for hematopoiesis or clonal hematopoiesis. CHIP is driven by mutations in genes such as Tet2, Dnmt3a, Asxl1, and Jak2, which are associated with age-related hematological malignancies.

OBJECTIVE

This literature review aims to provide an updated exploration of the functional aspects of BM niche cells within the hematopoietic microenvironment in the context of age-related hematological malignancies. The review specifically focuses on how immunological stressors modulate different signaling pathways that impact hematopoiesis.

METHODS

An extensive review of recent studies was conducted, examining the roles of various BM niche cells in hematopoietic stem cell (HSC) trafficking and the development of age-related hematological malignancies. Emphasis was placed on understanding the influence of immunological stressors on these processes.

RESULTS

Recent findings reveal a significant microheterogeneity and temporal stochasticity of niche cells across the BM during hematopoiesis. These studies demonstrate that niche cells, including mesenchymal stem cells, osteoblasts, and endothelial cells, exhibit dynamic interactions with HSCs, significantly influenced by the BM microenvironment as the age increases. Immunosurveillance plays a crucial role in maintaining hematopoietic homeostasis, with alterations in immune signaling pathways contributing to the onset of hematological malignancies. Novel insights into the interaction between niche cells and HSCs under stress/aging conditions highlight the importance of niche plasticity and adaptability.

CONCLUSION

The involvement of age-induced genetic/epigenetic alterations in BM niche cells and immunological stressors in hematopoiesis is crucial for understanding the development of age-related hematological malignancies. This comprehensive review provides new insights into the complex interplay between niche cells and HSCs, emphasizing the potential for novel therapeutic approaches that target niche cell functionality and resilience to improve hematopoietic outcomes in the context of aging and metabolic disorders.

NOVELTY STATEMENT

This review introduces novel concepts regarding the plasticity and adaptability of BM niche cells in response to immunological stressors and epigenetics. It proposes that targeted therapeutic strategies aimed at enhancing niche cell resilience could mitigate the adverse effects of aging, diabetes, and obesity on hematopoiesis and clonal hematopoiesis. Additionally, the review suggests that understanding the precise temporal and spatial dynamics of niche-HSC interactions and epigenetics influence may lead to innovative treatments for age-related hematological malignancies.

Adrenergic orchestration of immune cell dynamics in response to cardiac stress

Immune cells contribute approximately 5-10 % of the heart's total cell population, including several myeloid cell and lymphocyte cell subsets, which, despite their relatively small percentages, play important roles in cardiac homeostasis and remodeling responses to various forms of injury and long-term stress. Pathological cardiac stress activates the sympathetic nervous system (SNS), resulting in the release of the catecholamines epinephrine and norepinephrine either systemically or from sympathetic nerve terminals within various lymphoid organs. Acting at α- or β-adrenergic receptors (αAR, βAR), catecholamines regulate immune cell hematopoiesis, egress and migration in response to stress. Classically, αAR stimulation tends to promote inflammatory responses while βAR stimulation has typically been shown to be immunosuppressive, though the effects can be nuanced depending on the immune cells subtype, the site of regulation and pathophysiological context. Herein, we will discuss several facets of SNS-mediated regulation of immune cells and their response to cardiac stress, including: catecholamine response to cardiovascular stress and action at their receptors, adrenergic regulation of hematopoiesis, immune cell retention and release from the bone marrow, adrenergic regulation of splenic immune cells and their retention, as well as adrenergic regulation of immune cell recruitment to the injured heart, including neutrophils, monocytes and macrophages. A particular focus will be given to βAR-mediated effects on myeloid cells in response to acute or chronic cardiac stress.

A female-biased gene expression signature of dominance in cooperatively breeding meerkats

Dominance is a primary determinant of social dynamics and resource access in social animals. Recent studies show that dominance is also reflected in the gene regulatory profiles of peripheral immune cells. However, the strength and direction of this relationship differs across the species and sex combinations investigated, potentially due to variation in the predictors and energetic consequences of dominance status. Here, we investigated the association between social status and gene expression in the blood of wild meerkats (Suricata suricatta; n = 113 individuals), including in response to lipopolysaccharide, Gardiquimod (an agonist of TLR7, which detects single-stranded RNA in vivo) and glucocorticoid stimulation. Meerkats are cooperatively breeding social carnivores in which breeding females physically outcompete other females to suppress reproduction, resulting in high reproductive skew. They therefore present an opportunity to disentangle the effects of social dominance from those of sex per se. We identify a sex-specific signature of dominance, including 1045 differentially expressed genes in females but none in males. Dominant females exhibit elevated activity in innate immune pathways and a larger fold-change response to LPS challenge. Based on these results and a preliminary comparison to other mammals, we speculate that the gene regulatory signature of social status in the immune system depends on the determinants and energetic costs of social dominance, such that it is most pronounced in hierarchies where physical competition is important and reproductive skew is large. Such a pattern has the potential to mediate life history trade-offs between investment in reproduction versus somatic maintenance.

Increased white blood cell in young adults with family histories of alcohol and other substance use disorders

Individuals with a family history of alcohol or other substance use disorders (FH+) are at increased risk for developing alcohol and other substance use disorders (AUD/SUD) compared to individuals with no such family histories (FH-). FH+ young adults have blunted stress reactivity, lower cognitive performance and altered frontal white matter microstructure compared to FH- controls. We hypothesized that family history of AUD/SUD disrupts neuroendocrine regulation of the immune system in FH+ individuals, resulting in altered blood immune cell composition, inflammation and neurocognitive alterations that, ultimately, increases risk for AUD/SUD and associated psychopathology. We examined white blood cell (WBC) parameters derived from complete blood counts in FH+ (n = 37) and FH- (n = 77) young adults without AUD/SUD to test if immune system dysregulation is present in FH+ individuals. The total WBC count, number of neutrophils and number of monocytes and associated systemic inflammatory response index (SIRI) were significantly increased in the FH+ group. Further, WBC, neutrophil, monocyte counts and SIRI values were all positively correlated with FH density (number of biological parents and grandparents with AUD/SUD). These novel data are the first to identify an association between family history of AUD/SUD and increased circulating leukocytes, which is likely indicative of immune dysregulation in FH+ young adults prior to onset of AUD/SUD. Additional studies are warranted to characterize the functional relevance of the observed immune cell composition in FH+ individuals, but the notion that inexpensive and widely available blood tests may help identify addiction risk could be transformative.

Future Therapeutic Strategies for Alzheimer's Disease: Focus on Behavioral and Psychological Symptoms

Alzheimer's disease (AD) is a progressive, degenerative brain disorder that impairs memory and thinking skills, leading to significant economic and humanistic burdens. It is associated with various neuropsychiatric symptoms (NPS) such as anxiety, agitation, depression, aggression, apathy, and psychosis. NPSs are common in patients with AD, affecting up to 97% of individuals diagnosed with AD. The severity of NPS is linked to disease progression and cognitive decline. NPS in Alzheimer's disease leads to increased morbidity, mortality, caregiver burden, earlier nursing home placement, and higher healthcare costs. Despite their significant impact, clinical research on NPS in AD is limited. In clinical settings, accurately distinguishing and diagnosing NPS related to AD remains a challenge. Additionally, conventional treatments for NPS in AD are often ineffective, highlighting the need for new therapies that target these specific symptoms. Understanding these comorbidities can aid in early diagnosis and better management of AD. In this review, we provide a summary of the various neurological and psychiatric symptoms (NPS) associated with AD and new candidates under development for the treatment of NPS based on their therapeutic targets and mechanisms. On top of the conventional NPS studied so far, this review adds recent advancements in the understanding of social functional impairment in AD. This review also provides information that can contribute to the advancement of studies and translational research in this field by emphasizing therapeutic targets and mechanisms of action focused on AD-related NPS rather than conventional mechanisms targeted in AD drug development. Above all, considering the relative lack of research in this new field despite the importance of clinical, medical, and translational research, it may increase interest in NPS in AD, its pathophysiological mechanisms, and potential therapeutic candidates such as molecules with antioxidant potential.

Social Genomic Determinants of Health: Understanding the Molecular Pathways by Which Neighborhood Disadvantage Affects Cancer Outcomes

PURPOSE

Neighborhoods represent complex environments with unique social, cultural, physical, and economic attributes that have major impacts on disparities in health, disease, and survival. Neighborhood disadvantage is associated with shorter breast cancer recurrence-free survival (RFS) independent of individual-level (race, ethnicity, socioeconomic status, insurance, tumor characteristics) and health system-level determinants of health (receipt of guideline-concordant treatment). This persistent disparity in RFS suggests unaccounted mechanisms such as more aggressive tumor biology among women living in disadvantaged neighborhoods compared with advantaged neighborhoods. The objective of this article was to provide a clear framework and biological mechanistic explanation for how neighborhood disadvantage affects cancer survival.

METHODS

Development of a translational epidemiological framework that takes a translational disparities approach to study cancer outcome disparities through the lens of social genomics and social epigenomics.

RESULTS

The social genomic determinants of health, defined as the physiological gene regulatory pathways (ie, neural/endocrine control of gene expression and epigenetic processes) through which contextual factors, particularly one's neighborhood, can affect activity of the cancer genome and the surrounding tumor microenvironment to alter disease progression and treatment outcomes.

CONCLUSION

We propose a novel, multilevel determinants of health model that takes a translational epidemiological approach to evaluate the interplay between political, health system, social, psychosocial, individual, and social genomic determinants of health to understand social disparities in oncologic outcomes. In doing so, we provide a concrete biological pathway through which the effects of social processes and social epidemiology come to affect the basic biology of cancer and ultimately clinical outcomes and survival.

Dementia and Cognitive Decline: A HEALM Approach

Dementia and cognitive decline pose significant global public health challenges, with prevalence expected to rise in the coming decades. Lifestyle medicine offers a promising approach to mitigating cognitive issues through six key interventions: diet, physical activity, restorative sleep, social connections, stress management, and avoiding risky substances. Traditional methods like randomized controlled trials (RCTs) have limitations in capturing the long-term impacts of these interventions. To overcome these challenges, the American College of Lifestyle Medicine (ACLM) and the True Health Initiative (THI) developed the Hierarchies of Evidence Applied to Lifestyle Medicine (HEALM) framework, informed by the Evidence Threshold Pathway Mapping (ETPM) approach. This framework integrates diverse evidence sources to assess intervention effects over time. Applying HEALM, this review evaluates lifestyle factors' impact on dementia and cognitive decline. It finds strong evidence supporting plant-based nutrition, physical activity, restorative sleep, and avoiding risky substances in promoting cognitive health. Social connections may mitigate cognitive decline, while stress management requires further investigation due to inconclusive findings. Integrating these findings into public health strategies could effectively address the growing dementia burden and enhance overall well-being in aging populations, underscoring the need for continued research in cognitive health.

The brain-body energy conservation model of aging

Aging involves seemingly paradoxical changes in energy metabolism. Molecular damage accumulation increases cellular energy expenditure, yet whole-body energy expenditure remains stable or decreases with age. We resolve this apparent contradiction by positioning the brain as the mediator and broker in the organismal energy economy. As somatic tissues accumulate damage over time, costly intracellular stress responses are activated, causing aging or senescent cells to secrete cytokines that convey increased cellular energy demand (hypermetabolism) to the brain. To conserve energy in the face of a shrinking energy budget, the brain deploys energy conservation responses, which suppress low-priority processes, producing fatigue, physical inactivity, blunted sensory capacities, immune alterations and endocrine 'deficits'. We term this cascade the brain-body energy conservation (BEC) model of aging. The BEC outlines (1) the energetic cost of cellular aging, (2) how brain perception of senescence-associated hypermetabolism may drive the phenotypic manifestations of aging and (3) energetic principles underlying the modifiability of aging trajectories by stressors and geroscience interventions.

The impact of social relationships on the risk of stroke and post-stroke mortality: a systematic review and meta-analysis

BACKGROUND

The association between poor social relationships and post-stroke mortality remains uncertain, and the evidence regarding the relationship between poor social relationships and the risk of stroke is inconsistent. In this meta-analysis, we aim to elucidate the evidence concerning the risk of stroke and post-stroke mortality among individuals experiencing a poor social relationships, including social isolation, limited social networks, lack of social support, and loneliness.

METHODS

A thorough search of PubMed, Embase, and the Cochrane Library databases to systematically identify pertinent studies. Data extraction was independently performed by two researchers. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using either a random-effects or fixed-effects model. Sensitivity analyses were conducted to evaluate the reliability of the results. Random-effects meta-regression was performed to explore the sources of heterogeneity in stroke risk estimates between studies. Assessment for potential publication bias was carried out using Egger's and Begg's tests.

RESULTS

Nineteen studies were included, originating from 4 continents and 12 countries worldwide. A total of 1,675,707 participants contributed to this meta-analysis. Pooled analyses under the random effect model revealed a significant association between poor social relationships and the risk of stroke (OR = 1.30; 95%CI: 1.17-1.44), as well as increased risks for post-stroke mortality (OR = 1.36; 95%CI: 1.07-1.73). Subgroup analyses demonstrated associations between limited social network (OR = 1.52; 95%CI = 1.04-2.21), loneliness (OR = 1.31; 95%CI = 1.13-1.51), and lack of social support (OR = 1.66; 95%CI = 1.04-2.63) with stroke risk. The meta-regression explained 75.21% of the differences in reported stroke risk between studies. Random-effect meta-regression results indicate that the heterogeneity in the estimated risk of stroke may originate from the continent and publication year of the included studies.

CONCLUSION

Social isolation, limited social networks, lack of social support, and feelings of loneliness have emerged as distinct risk factors contributing to both the onset and subsequent mortality following a stroke. It is imperative for public health policies to prioritize the multifaceted influence of social relationships and loneliness in stroke prevention and post-stroke care.

TRIAL REGISTRATION

The protocol was registered on May 1, 2024, on the Prospero International Prospective System with registration number CRD42024531036.

Association Between Social Isolation With Age-Gap Determined by Artificial Intelligence-Enabled Electrocardiography

Background

Loneliness and social isolation are associated with poor health outcomes such as an increased risk of cardiovascular diseases.

Objectives

The authors aimed to explore the association between social isolation with biological aging which was determined by artificial intelligence-enabled electrocardiography (AI-ECG) as well as the risk of all-cause mortality.

Methods

The study included adults aged ≥18 years seen at Mayo Clinic from 2019 to 2022 who respond to a survey for social isolation assessment and had a 12-lead ECG within 1 year of completing the questionnaire. Biological age was determined from ECGs using a previously developed and validated convolutional neural network (AI-ECG age). Age-Gap was defined as AI-ECG age minus chronological age, where positive values reflect an older-than-expected age. The status of social isolation was measured by the previously validated multiple-choice questions based on Social Network Index (SNI) with score ranges between 0 (most isolated) and 4 (least isolated).

Results

A total of 280,324 subjects were included (chronological age 59.8 ± 16.4 years, 50.9% female). The mean Age-Gap was -0.2 ± 9.16 years. A higher SNI was associated with a lower Age-Gap (β of SNI = 4 was -0.11; 95% CI: -0.22 to -0.01; P < 0.001, adjusted to covariates). Cox proportional hazard analysis revealed the association between social connection and all-cause mortality (HR for SNI = 4, 0.47; 95% CI: 0.43-0.5; P < 0.001).

Conclusions

Social isolation is associated with accelerating biological aging and all-cause mortality independent of conventional cardiovascular risk factors. This observation underscores the need to address social connection as a health care determinant.

Exploring the interplay between stress mediators and skin microbiota in shaping age-related hallmarks: A review

Psychological stress is a major contributing factor to several health problems (e.g., depression, cardiovascular disease). Around 35 % of the world's population suffers from it, including younger generations. Physiologically, stress manifests through neuroendocrine pathways (Hypothalamic-Pituitary-Adrenal (HPA) axis and Sympathetic-Adrenal-Medullary (SAM) system) which culminate in the production of stress mediators like cortisol, epinephrine and norepinephrine. Stress and its mediators have been associated to body aging, through molecular mechanisms such as telomere attrition, mitochondrial dysfunction, cellular senescence, chronic inflammation, and dysbiosis, among others. Regarding its impact in the skin, stress impacts its structural integrity and physiological function. Despite this review focusing on several hallmarks of aging, emphasis was placed on skin microbiota dysbiosis. In this line, several studies, comprising different age groups, demographic contexts and body sites, have reported skin microbiota alterations associated with aging, and some effects of stress mediators on skin microbiota have also been reviewed in this paper. From a different perspective, since it is not a "traditional" stress mediator, oxytocin, a cortisol antagonist, has been related to glucorticoids inhibition and to display positive effects on cellular aging. This hormone dysregulation has been associated to psychological issues such as depression, whereas its upregulation has been linked to positive social interaction.

Social defeat stress impairs systemic iron metabolism by activating the hepcidin-ferroportin axis

Chronic psychological stress has been reported to decrease circulating iron concentrations and impair hematopoiesis. However, the underlying mechanisms remain unclear. This study aimed to investigate the effects of psychological stress on biological iron metabolism by using the social defeat stress (SDS) model, a widely used model of depression. Compared with control mice, mice subjected to SDS (SDS mice) had lower social interaction (SI) behavior. The SDS mice also showed impaired hematopoiesis, as evidenced by reduced circulating red blood cell counts, elevated reticulocyte counts, and decreased plasma iron levels. In the SDS mice, the iron contents in the bone marrow decreased, whereas those in the spleen increased, suggesting dysregulation in systemic iron metabolism. The concentrations of plasma hepcidin, an important regulator of systemic iron homeostasis, increased in the SDS mice. Meanwhile, the concentrations of ferroportin, an iron transport protein negatively regulated by hepcidin, were lower in the spleen and duodenum of the SDS mice than in those of the control mice. Treatment with dalteparin, a hepcidin inhibitor, prevented the decrease in plasma iron levels in the SDS mice. The gene expression and enzyme activity of furin, which converts the precursor hepcidin to active hepcidin, were high and positively correlated with plasma hepcidin concentration. Thus, furin activation might be responsible for the increased plasma hepcidin concentration. This study is the first to show that psychological stress disrupts systemic iron homeostasis by activating the hepcidin-ferroportin axis. Consideration of psychological stressors might be beneficial in the treatment of diseases with iron-refractory anemia.

The health risk of social disadvantage is transplantable into a new host

Low socioeconomic status (SES) is a risk factor for mortality and immune dysfunction across a wide range of diseases, including cancer. However, cancer is distinct in the use of allogeneic hematopoietic cell transplantation (HCT) as a treatment for hematologic malignancies to transfer healthy hematopoietic cells from one person to another. This raises the question of whether social disadvantage of an HCT cell donor, as assessed by low SES, might impact the subsequent health outcomes of the HCT recipient. To evaluate the cellular transplantability of SES-associated health risk, we analyzed the health outcomes of 2,005 HCT recipients who were transplanted for hematologic malignancy at 125 United States transplant centers and tested whether their outcomes differed as a function of their cell donor's SES (controlling for other known HCT-related risk factors). Recipients transplanted with cells from donors in the lowest quartile of SES experienced a 9.7% reduction in overall survival (P = 0.001) and 6.6% increase in treatment-related mortality within 3 y (P = 0.008) compared to those transplanted from donors in the highest SES quartile. These results are consistent with previous research linking socioeconomic disadvantage to altered immune cell function and hematopoiesis, and they reveal an unanticipated persistence of those effects after cells are transferred into a new host environment. These SES-related disparities in health outcomes underscore the need to map the biological mechanisms involved in the social determinants of health and develop interventions to block those effects and enhance the health of both HCT donors and recipients.

Beta2 adrenergic receptor-mediated abnormal myelopoiesis drives neuroinflammation in aged patients with traumatic brain injury

Aged patients often suffer poorer neurological recovery than younger patients after traumatic brain injury (TBI), but the mechanisms underlying this difference remain unclear. Here, we demonstrate abnormal myelopoiesis characterized by increased neutrophil and classical monocyte output but impaired nonclassical patrolling monocyte population in aged patients with TBI as well as in an aged murine TBI model. Retrograde and anterograde nerve tracing indicated that increased adrenergic input through the central amygdaloid nucleus-bone marrow axis drives abnormal myelopoiesis after TBI in a β2-adrenergic receptor-dependent manner, which is notably enhanced in aged mice after injury. Selective blockade of β2-adrenergic receptors rebalances abnormal myelopoiesis and improves the outcomes of aged mice after TBI. We therefore demonstrate that increased β2-adrenergic input-driven abnormal myelopoiesis exacerbates post-TBI neuroinflammation in the aged, representing a mechanism underlying the poorer recovery of aged patients and that blockade of β2-adrenergic receptor is a potential approach to promote neurological recovery after TBI.

Neurobiology and systems biology of stress resilience

Stress resilience is the phenomenon that some people maintain their mental health despite exposure to adversity or show only temporary impairments followed by quick recovery. Resilience research attempts to unravel the factors and mechanisms that make resilience possible and to harness its insights for the development of preventative interventions in individuals at risk for acquiring stress-related dysfunctions. Biological resilience research has been lagging behind the psychological and social sciences but has seen a massive surge in recent years. At the same time, progress in this field has been hampered by methodological challenges related to finding suitable operationalizations and study designs, replicating findings, and modeling resilience in animals. We embed a review of behavioral, neuroimaging, neurobiological, and systems biological findings in adults in a critical methods discussion. We find preliminary evidence that hippocampus-based pattern separation and prefrontal-based cognitive control functions protect against the development of pathological fears in the aftermath of singular, event-type stressors [as found in fear-related disorders, including simpler forms of posttraumatic stress disorder (PTSD)] by facilitating the perception of safety. Reward system-based pursuit and savoring of positive reinforcers appear to protect against the development of more generalized dysfunctions of the anxious-depressive spectrum resulting from more severe or longer-lasting stressors (as in depression, generalized or comorbid anxiety, or severe PTSD). Links between preserved functioning of these neural systems under stress and neuroplasticity, immunoregulation, gut microbiome composition, and integrity of the gut barrier and the blood-brain barrier are beginning to emerge. On this basis, avenues for biological interventions are pointed out.

Early life adversity is associated with differential gene expression in immune cells: A cluster-based analysis across an acute psychosocial stressor

Elucidating mechanisms by which early-life adversity (ELA) contributes to increased disease risk is important for mitigating adverse health outcomes. Prior work has found differences in immune cell gene expression related to inflammation and mitochondrial activity. Using a within-person between-group experimental design, we investigated differences in gene expression clusters across acute psychosocial stress and no-stress conditions. Participants were young adults (N = 29, aged 18 - 25 years, 62 % female, 47 % with a history of ELA). Gene expression was assessed in peripheral blood mononuclear cells collected at 8 blood draws spanning two 5-hour sessions (stress vs. no-stress) separated by a week, 4 across each session (number of observations = 221). We applied two unsupervised gene clustering methods - latent profile analysis (LPA) and weighted gene co-expression analysis (WGCNA) - to cluster genes with similar expression patterns across participants. LPA identified 11 clusters, 7 of which were significantly associated with ELA-status. WGCNA identified 5 clusters, 3 of which were significantly associated with ELA-status. LPA- and WGCNA-identified clusters were correlated, and all clusters were highly preserved across sessions and time. There was no significant effect of acute stress on cluster gene expression, but there was a significant effect of time, and significant differences by ELA-status. ELA-associated clusters related to RNA splicing/processing, inflammation, leukocyte differentiation and division, and mitochondrial activity were differentially expressed across time: ELA-exposed individuals showed decreased expression of these clusters at 90-minutes while controls showed increased expression. Our findings replicate previous work in this area and highlight additional mechanisms by which ELA may contribute to disease risk.

Neurobiological basis of stress resilience

A majority of humans faced with severe stress maintain normal physiological and behavioral function, a process referred to as resilience. Such stress resilience has been modeled in laboratory animals and, over the past 15 years, has transformed our understanding of stress responses and how to approach the treatment of human stress disorders such as depression, post-traumatic stress disorder (PTSD), and anxiety disorders. Work in rodents has demonstrated that resilience to chronic stress is an active process that involves much more than simply avoiding the deleterious effects of the stress. Rather, resilience is mediated largely by the induction of adaptations that are associated uniquely with resilience. Such mechanisms of natural resilience in rodents are being characterized at the molecular, cellular, and circuit levels, with an increasing number being validated in human investigations. Such discoveries raise the novel possibility that treatments for human stress disorders, in addition to being geared toward reversing the damaging effects of stress, can also be based on inducing mechanisms of natural resilience in individuals who are inherently more susceptible. This review provides a progress report on this evolving field.

A single-arm, open-label pilot study of neuroimaging, behavioral, and peripheral inflammatory correlates of mindfulness-based stress reduction in multiple sclerosis

Multiple sclerosis (MS) is a chronic neurological disease frequently associated with significant fatigue, anxiety, depression, and stress. These symptoms are difficult to treat, and prominently contribute to the decreases in quality of life observed with MS. The underlying mechanisms of these "silent" symptoms are not well understood and include not just the psychological responses to a chronic disease, but also biological contributions from bidirectional psycho-neuro-immune (dys)regulation of systemic inflammatory biology. To address these issues, we conducted a prospective, observational pilot study to investigate the psychological, biological, and neuroarchitecture changes associated with a mindfulness-based stress reduction (MBSR) program in MS. The overarching hypothesis was that MBSR modulates systemic and central nervous system inflammation via top-down neurocognitive control over forebrain limbic areas responsible for the neurobiological stress response. 23 patients were enrolled in MBSR and assessed pre/post-program with structural 3 T MRI, behavioral measures, hair cortisol, and blood measures of peripheral inflammation, as indexed by the Conserved Transcriptional Response to Adversity (CTRA) profile. MBSR was associated with improvements across a variety of behavioral outcomes, as well as on-study enlargement of the head of the right hippocampus. The CTRA analyses revealed that greater inflammatory gene expression was related to worse patient-reported anxiety, depression, stress, and loneliness, in addition to lower eudaimonic well-being. Hair cortisol did not significantly change from pre- to post-MBSR. These results support the use of MBSR in MS and elucidate inflammatory mechanisms related to key patient-reported outcomes in this population.

Reconsidering the role of depression and common psychiatric disorders as partners in the type 2 diabetes epidemic

Common psychiatric disorders (CPDs) and depression contribute significantly to the global epidemic of type 2 diabetes (T2D). We postulated a possible pathophysiological mechanism that through Bridge-Symptoms present in depression and CPDs, promotes the establishment of emotional eating, activation of the reward system, onset of overweight and obesity and, ultimately the increased risk of developing T2D. The plausibility of the proposed pathophysiological mechanism is supported by the mechanism of action of drugs such as naltrexone-bupropion currently approved for the treatment of both obesity/overweight with T2D and as separate active pharmaceutical ingredients in drug addiction, but also from initial evidence that is emerging regarding glucagon-like peptide 1 receptor agonists that appear to be effective in the treatment of drug addiction. We hope that our hypothesis may be useful in interpreting the higher prevalence of CPDs and depression in patients with T2D compared with the general population and may help refine the integrated psychiatric-diabetic therapy approach to improve the treatment and or remission of T2D.

Interactions between MDSCs and the Autonomic Nervous System: Opportunities and Challenges in Cancer Neuroscience

Myeloid-derived suppressor cells (MDSC) are a population of heterogeneous immune cells that are involved in precancerous conditions and neoplasms. The autonomic nervous system (ANS), which is composed of the sympathetic nervous system and the parasympathetic nervous system, is an important component of the tumor microenvironment that responds to changes in the internal and external environment mainly through adrenergic and cholinergic signaling. An abnormal increase of autonomic nerve density has been associated with cancer progression. As we discuss in this review, growing evidence indicates that sympathetic and parasympathetic signals directly affect the expansion, mobilization, and redistribution of MDSCs. Dysregulated autonomic signaling recruits MDSCs to form an immunosuppressive microenvironment in chronically inflamed tissues, resulting in abnormal proliferation and differentiation of adult stem cells. The two components of the ANS may also be responsible for the seemingly contradictory behaviors of MDSCs. Elucidating the underlying mechanisms has the potential to provide more insights into the complex roles of MDSCs in tumor development and lay the foundation for the development of novel MDSC-targeted anticancer strategies.

Loneliness, epigenetic age acceleration, and chronic health conditions

Having associations with a range of adverse physical health outcomes including mortality, loneliness is increasingly recognized as a pressing public health concern, but the mechanisms studied to date do not yet explain all loneliness-related health risk. We sought to evaluate whether epigenetic influences on DNA methylation could help explain the relationship between loneliness and health. To do so, we first estimated associations between loneliness and epigenetic age acceleration (EAA) in a subsample of participants in the study of midlife in the United States (n = 1,310), before testing whether EAA mediated and/or moderated the association between loneliness and the onset of chronic health conditions in older adulthood (n = 445 completing longitudinal follow-ups). Greater loneliness was weakly associated with greater EAA in the Horvath, DunedinPACE, and GrimAge measures after accounting for demographic (0.08 ≤ β ≤ 0.11) and behavioral (0.06 ≤ β ≤ 0.08) covariates. Loneliness also predicted increases in chronic condition counts and these effects were more pronounced for individuals with higher DunedinPACE EAA values (interaction term β = 0.09, p = .009), suggesting possible synergistic impacts. EAA measures appear to be promising in helping to understand individual variations in the health impacts of loneliness, but the specific mechanisms involved require further research. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Identification of shared potential diagnostic markers in asthma and depression through bioinformatics analysis and machine learning

BACKGROUND

There is mounting evidence that asthma might exacerbate depression. We sought to examine candidates for diagnostic genes in patients suffering from asthma and depression.

METHODS

Microarray data were downloaded from the Gene Expression Omnibus(GEO) database and used to screen for differential expressed genes(DEGs) in the SA and MDD datasets. A weighted gene co-expression network analysis(WGCNA) was used to identify the co-expression modules of SA and MDD. The least absolute shrinkage and selection operatoes(LASSO) and support vector machine(SVM) were used to determine critical biomarkers. Immune cell infiltration analysis was used to investigate the correlation between immune cell infiltration and common biomarkers of SA and MDD. Finally, validation of these analytical results was accomplished via the use of both in vivo and in vitro studies.

RESULTS

The number of DEGs that were included in the MDD dataset was 5177, whereas the asthma dataset had 1634 DEGs. The intersection of DEGs for SA and MDD included 351 genes, the strongest positive modules of SA and MDD was 119 genes, which played a function in immunity. The intersection of DEGs and modular hub genes was 54, following the analysis using machine learning algorithms,three hub genes were identified and employed to formulate a nomogram and for the evaluation of diagnostic effectiveness, which demonstrated a significant diagnostic value (area under the curve from 0.646 to 0.979). Additionally, immunocyte disorder was identified by immune infiltration. In vitro studies have revealed that STK11IP deficiency aggravated the LPS/IFN-γinduced up-regulation in M1 macrophage activation.

CONCLUSION

Asthma and MDD pathophysiology may be associated with alterations in inflammatory processes and immune pathways. Additionally, STK11IP may serve as a diagnostic marker for individuals with the two conditions.

Systemic Inflammation in Asthma: What Are the Risks and Impacts Outside the Airway?

Airway inflammation in asthma has been well recognized for several decades, with general agreement on its role in asthma pathogenesis, symptoms, propensity toward exacerbation, and decline in lung function. This has led to universal recommendation in asthma management guidelines to incorporate the use of inhaled corticosteroid as an anti-inflammatory therapy for all patients with persistent asthma symptoms. However, there has been limited attention paid to the presence and potential impact of systemic inflammation in asthma. Accumulating evidence from epidemiological observations and cohort studies points to a host of downstream organ dysfunction in asthma especially among patients with longstanding or more severe disease, frequent exacerbations, and underlying risk factors for organ dysfunction. Most studies to date have focused on cognitive impairment, depression/anxiety, metabolic syndrome, and cardiovascular abnormalities. In this review, we summarize some of the evidence demonstrating these abnormalities and highlight the proposed mechanisms and potential benefits of treatment in limiting these extrapulmonary abnormalities in patients with asthma. The goal of this commentary is to raise awareness of the importance of recognizing potential extrapulmonary conditions associated with systemic inflammation of asthma. This area of treatment of patients with asthma is a large unmet need.

The cancer-immune dialogue in the context of stress

Although there is little direct evidence supporting that stress affects cancer incidence, it does influence the evolution, dissemination and therapeutic outcomes of neoplasia, as shown in human epidemiological analyses and mouse models. The experience of and response to physiological and psychological stressors can trigger neurological and endocrine alterations, which subsequently influence malignant (stem) cells, stromal cells and immune cells in the tumour microenvironment, as well as systemic factors in the tumour macroenvironment. Importantly, stress-induced neuroendocrine changes that can regulate immune responses have been gradually uncovered. Numerous stress-associated immunomodulatory molecules (SAIMs) can reshape natural or therapy-induced antitumour responses by engaging their corresponding receptors on immune cells. Moreover, stress can cause systemic or local metabolic reprogramming and change the composition of the gastrointestinal microbiota which can indirectly modulate antitumour immunity. Here, we explore the complex circuitries that link stress to perturbations in the cancer-immune dialogue and their implications for therapeutic approaches to cancer.

Retention of stress susceptibility in the mdx mouse model of Duchenne muscular dystrophy after PGC-1α overexpression or ablation of IDO1 or CD38

Duchenne muscular dystrophy (DMD) is a lethal degenerative muscle wasting disease caused by the loss of the structural protein dystrophin with secondary pathological manifestations including metabolic dysfunction, mood and behavioral disorders. In the mildly affected mdx mouse model of DMD, brief scruff stress causes inactivity, while more severe subordination stress results in lethality. Here, we investigated the kynurenine pathway of tryptophan degradation and the nicotinamide adenine dinucleotide (NAD+) metabolic pathway in mdx mice and their involvement as possible mediators of mdx stress-related pathology. We identified downregulation of the kynurenic acid shunt, a neuroprotective branch of the kynurenine pathway, in mdx skeletal muscle associated with attenuated peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) transcriptional regulatory activity. Restoring the kynurenic acid shunt by skeletal muscle-specific PGC-1α overexpression in mdx mice did not prevent scruff -induced inactivity, nor did abrogating extrahepatic kynurenine pathway activity by genetic deletion of the pathway rate-limiting enzyme, indoleamine oxygenase 1. We further show that reduced NAD+ production in mdx skeletal muscle after subordination stress exposure corresponded with elevated levels of NAD+ catabolites produced by ectoenzyme cluster of differentiation 38 (CD38) that have been implicated in lethal mdx response to pharmacological β-adrenergic receptor agonism. However, genetic CD38 ablation did not prevent mdx scruff-induced inactivity. Our data do not support a direct contribution by the kynurenine pathway or CD38 metabolic dysfunction to the exaggerated stress response of mdx mice.

Acute psychological stress-induced progenitor cell mobilization and cardiovascular events

OBJECTIVE

Certain brain activation responses to psychological stress are associated with worse outcomes in CVD patients. We hypothesized that elevated acute psychological stress, manifesting as greater activity within neural centers for emotional regulation, mobilizes CPC from the bone marrow to the peripheral blood and predicts future cardiovascular events.

METHODS

In 427 patients with stable CAD undergoing a laboratory-based mental stress (MS) test, CPCs were enumerated using flow cytometry as CD34-expressing mononuclear cells (CD34+) before and 45 min after stress. Changes in brain regional blood flow with MS were measured using high resolution-positron emission tomography (HR-PET). Association between the change in CPC with MS and the risk of cardiovascular death or myocardial infarction (MI) during a 5-year follow-up period was analyzed.

RESULTS

MS increased CPC counts by a mean of 150 [630] cells/mL (15%), P < 0.001. Greater limbic lobe activity, indicative of activation of emotion-regulating centers, was associated with greater CPC mobilization (P < 0.005). Using Fine and Gray models after adjustment for demographioc, clinical risk factors and medications use, greater CPC mobilization was associated with a higher adjusted risk of adverse events; a rise of 1000 cells/mL was associated with a 50% higher risk of cardiovascular death/MI [hazards ratio, 1.5, 95% confidence interval, 1.1-2.2).

CONCLUSION

Greater limbic lobe activity, brain areas involved in emotional regulation, is associated with MS-induced CPC mobilization. This mobilization isindependently associated with cardiovascular events. These findings provide novel insights into mechanisms through which psychological stressors modulate cardiovascular risk.

Peer support as moderator of association between socioeconomic status and low-grade inflammation in adolescents

OBJECTIVE

Individuals who grow up in low-socioeconomic status (SES) families are at an increased risk of health problems across the lifespan. Although supportive social relationships are postulated to be a protective factor for the health of these individuals, the role of friend support in adolescence is not well understood. Given that low-grade inflammation is one key biological mechanism proposed to explain links between family SES and health outcomes, we examined whether adolescents' friend support buffers the association between family SES and low-grade inflammation among adolescents.

METHOD

277 dyads of adolescents (63.5% female; 39.4% White, 38.3% Black, and 32.1% Hispanic; Mage = 13.92 years) and one of their parents participated in this longitudinal study (two waves approximately 2 years apart). Parents reported family objective SES (i.e., income, savings, and education) and family subjective SES (i.e., subjective social status). Adolescents reported perceived friend support. Fasting antecubital blood was drawn from adolescents at both visits. Low-grade inflammatory activity was represented by a composite of inflammatory biomarkers and numbers of classical monocytes.

RESULTS

Adolescents' friend support moderated the associations of family subjective SES with both the inflammation composite and classical monocyte counts across cross-sectional, longitudinal, and prospective change (only significant for the inflammation composite) analyses. Specifically, lower family subjective SES was associated with higher levels of low-grade inflammation only among adolescents lower, but not higher, in friend support. No moderation was observed for objective SES.

CONCLUSION

Supportive peer relationships buffer the link between family subjective, but not objective, SES and low-grade inflammation in adolescence. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Risk of Social Isolation as a Contributing Factor to Diet Quality in Community-Dwelling Older Persons Living in the Australian Capital Territory-A Pilot Study

OBJECTIVES

Social isolation is recognised as a risk factor in the inflammatory process. This study explored the association between social isolation and the Dietary Inflammatory Index (DII) in community-dwelling older persons.

METHODS

This cross-sectional pilot study recruited 107 community-dwelling people aged over 55 years living in the Australian Capital Territory. Participants completed an extensive food frequency questionnaire and provided anthropometric and sociodemographic data. Social isolation was evaluated using the Lubben Social Network Scale (LSNS). Diet quality was assessed using DII.

RESULTS

Average age was 70.1 (±8.61) years and 62.8% were female. The average DII score was -1.10 (±1.21), indicating an anti-inflammatory diet. Higher LSNS was associated with lower DII (b (95% CI) = -0.041 (-0.066, -0.17); p < 0.01) and was positively influenced by the number of people in household (b (95% CI) = 5.731 (2.336, 9.127); p = 0.001).

CONCLUSION

Increased risk of social isolation was associated with an increased tendency towards a more inflammatory diet. Reducing social isolation may decrease the inflammatory component of dietary intake for older persons living independently in the community.

Environmental enrichment improves cognitive function, learning, memory and anxiety-related behaviours in rodent models of dementia: Implications for future study

Environmental enrichment (EE) is a process of brain stimulation by modifying the surroundings, for example, by changing the sensory, social, or physical conditions. Rodents have been used in such experimental strategies through exposure to diverse physical, social, and exploration conditions. The present study conducted an extensive analysis of the existing literature surrounding the impact of EE on dementia rodent models. The review emphasised the two principal aspects that are very closely related to dementia: cognitive function (learning and memory) as well as psychological factors (anxiety-related behaviours such as phobias and unrealistic worries). Also highlighted were the mechanisms involved in the rodent models of dementia showing EE effects. Two search engines, PubMed and Science Direct, were used for data collection using the following keywords: environmental enrichment, dementia, rodent model, cognitive performance, and anxiety-related behaviour. Fifty-five articles were chosen depending on the criteria for inclusion and exclusion. The rodent models with dementia demonstrated improved learning and memory in the form of hampered inflammatory responses, enhanced neuronal plasticity, and sustained neuronal activity. EE housing also prevented memory impairment through the prevention of amyloid beta (Aβ) seeding formation, an early stage of Aβ plaque formation. The rodents subjected to EE were observed to present increased exploratory activity and exert less anxiety-related behaviour, compared to those in standard housing. However, some studies have proposed that EE intervention through exercise would be too mild to counteract the anxiety-related behaviour and risk assessment behaviour deficits in the Alzheimer's disease rodent model. Future studies should be conducted on old-aged rodents and the duration of EE exposure that would elicit the greatest benefits since the existing studies have been conducted on a range of ages and EE durations. In summary, EE had a considerable effect on dementia rodent models, with the most evident being improved cognitive function.

C-reactive protein moderates associations between racial discrimination and ventromedial prefrontal cortex activation during attention to threat in Black American women

Prior research has shown that racial discrimination (RD) impacts activation in threat network regions, including the ventromedial prefrontal cortex (vmPFC) and middle occipital cortex during attention to threat-relevant stimuli. However, little is known about the biological mechanisms that may modulate these effects; inflammation may be a pathway linking RD and threat network activation. As such, the current study aimed to explore whether systemic inflammation, measured by C-reactive protein (CRP) levels, may moderate the relationship between RD and activation in the vmPFC and middle occipital cortex during attention to threat. Blood samples for inflammatory marker (CRP) assays were obtained from forty Black American women (mean [SD] age, 39.93 [9.97] years; range, 22-58 years) recruited from an ongoing trauma study; participants also viewed threat-relevant stimuli as part of an attention task during fMRI. We found that CRP moderated the relationship between RD and vmPFC activation during attention to threat, such that participants with relatively higher concentrations of CRP ( ≥ 23.97 mg/L) demonstrated significant positive associations between RD and vmPFC activation [β = 0.18, CI (0.04, 0.32), t = 2.65, p = 0.01]. No significant associations were observed for participants who showed moderate (10.89 mg/L) or low (0.20 mg/L) CRP concentrations. CRP did not moderate the relationship between RD and middle occipital cortex activation. Our data present a mechanism through which RD may influence immune system activation and, in turn, threat network activation. Inflammation may contribute to brain health vulnerabilities in Black Americans via its effects on threat circuits; this merits further investigation in large-scale studies.

Circulating myeloid-derived MMP8 in stress susceptibility and depression

Psychosocial stress has profound effects on the body, including the immune system and the brain1,2. Although a large number of pre-clinical and clinical studies have linked peripheral immune system alterations to stress-related disorders such as major depressive disorder (MDD)3, the underlying mechanisms are not well understood. Here we show that expression of a circulating myeloid cell-specific proteinase, matrix metalloproteinase 8 (MMP8), is increased in the serum of humans with MDD as well as in stress-susceptible mice following chronic social defeat stress (CSDS). In mice, we show that this increase leads to alterations in extracellular space and neurophysiological changes in the nucleus accumbens (NAc), as well as altered social behaviour. Using a combination of mass cytometry and single-cell RNA sequencing, we performed high-dimensional phenotyping of immune cells in circulation and in the brain and demonstrate that peripheral monocytes are strongly affected by stress. In stress-susceptible mice, both circulating monocytes and monocytes that traffic to the brain showed increased Mmp8 expression following chronic social defeat stress. We further demonstrate that circulating MMP8 directly infiltrates the NAc parenchyma and controls the ultrastructure of the extracellular space. Depleting MMP8 prevented stress-induced social avoidance behaviour and alterations in NAc neurophysiology and extracellular space. Collectively, these data establish a mechanism by which peripheral immune factors can affect central nervous system function and behaviour in the context of stress. Targeting specific peripheral immune cell-derived matrix metalloproteinases could constitute novel therapeutic targets for stress-related neuropsychiatric disorders.

Socioeconomic inequalities in early adulthood disrupt the immune transcriptomic landscape via upstream regulators

Disparities in socio-economic status (SES) predict many immune system-related diseases, and previous research documents relationships between SES and the immune cell transcriptome. Drawing on a bioinformatically-informed network approach, we situate these findings in a broader molecular framework by examining the upstream regulators of SES-associated transcriptional alterations. Data come from the National Longitudinal Study of Adolescent to Adult Health (Add Health), a nationally representative sample of 4543 adults in the United States. Results reveal a network-of differentially expressed genes, transcription factors, and protein neighbors of transcription factors-that shows widespread SES-related dysregulation of the immune system. Mediational models suggest that body mass index (BMI) plays a key role in accounting for many of these associations. Overall, the results reveal the central role of upstream regulators in socioeconomic differences in the molecular basis of immunity, which propagate to increase risk of chronic health conditions in later-life.

Distinguishing features of depression in dementia from primary psychiatric disease

Depression is a common and devastating neuropsychiatric symptom in the elderly and in patients with dementia. In particular, nearly 80% of patients with Alzheimer's Disease dementia experience depression during disease development and progression. However, it is unknown whether the depression in patients with dementia shares the same molecular mechanisms as depression presenting as primary psychiatric disease or occurs and persists through alternative mechanisms. In this review, we discuss how the clinical presentation and treatment differ between depression in dementia and as a primary psychiatric disease, with a focus on major depressive disorder. Then, we hypothesize several molecular mechanisms that may be unique to depression in dementia such as neuropathological changes, inflammation, and vascular events. Finally, we discuss existing issues and future directions for investigation and treatment of depression in dementia.

Pain-sensorimotor interactions: New perspectives and a new model

How pain and sensorimotor behavior interact has been the subject of research and debate for many decades. This article reviews theories bearing on pain-sensorimotor interactions and considers their strengths and limitations in the light of findings from experimental and clinical studies of pain-sensorimotor interactions in the spinal and craniofacial sensorimotor systems. A strength of recent theories is that they have incorporated concepts and features missing from earlier theories to account for the role of the sensory-discriminative, motivational-affective, and cognitive-evaluative dimensions of pain in pain-sensorimotor interactions. Findings acquired since the formulation of these recent theories indicate that additional features need to be considered to provide a more comprehensive conceptualization of pain-sensorimotor interactions. These features include biopsychosocial influences that range from biological factors such as genetics and epigenetics to psychological factors and social factors encompassing environmental and cultural influences. Also needing consideration is a mechanistic framework that includes other biological factors reflecting nociceptive processes and glioplastic and neuroplastic changes in sensorimotor and related brain and spinal cord circuits in acute or chronic pain conditions. The literature reviewed and the limitations of previous theories bearing on pain-sensorimotor interactions have led us to provide new perspectives on these interactions, and this has prompted our development of a new concept, the Theory of Pain-Sensorimotor Interactions (TOPSMI) that we suggest gives a more comprehensive framework to consider the interactions and their complexity. This theory states that pain is associated with plastic changes in the central nervous system (CNS) that lead to an activation pattern of motor units that contributes to the individual's adaptive sensorimotor behavior. This activation pattern takes account of the biological, psychological, and social influences on the musculoskeletal tissues involved in sensorimotor behavior and on the plastic changes and the experience of pain in that individual. The pattern is normally optimized in terms of biomechanical advantage and metabolic cost related to the features of the individual's musculoskeletal tissues and aims to minimize pain and any associated sensorimotor changes, and thereby maintain homeostasis. However, adverse biopsychosocial factors and their interactions may result in plastic CNS changes leading to less optimal, even maladaptive, sensorimotor changes producing motor unit activation patterns associated with the development of further pain. This more comprehensive theory points towards customized treatment strategies, in line with the management approaches to pain proposed in the biopsychosocial model of pain.

Chronic Stress as a Risk Factor for Type 2 Diabetes: Endocrine, Metabolic, and Immune Implications

BACKGROUND

Chronic stress is a condition of pressure on the brain and whole body, which in the long term may lead to a frank disease status, even including type 2 diabetes (T2D). Stress activates the hypothalamus-pituitary-adrenal axis with release of glucocorticoids (GCs) and catecholamines, as well as activation of the inflammatory pathway of the immune system, which alters glucose and lipid metabolism, ultimately leading to beta-cell destruction, insulin resistance and T2D onset. Alteration of the glucose and lipid metabolism accounts for insulin resistance and T2D outcome. Furthermore, stress-related subversion of the intestinal microbiota leads to an imbalance of the gut-brain-immune axis, as evidenced by the stress-related depression often associated with T2D. A condition of generalized inflammation and subversion of the intestinal microbiota represents another facet of stress-induced disease. In fact, chronic stress acts on the gut-brain axis with multiorgan consequences, as evidenced by the association between depression and T2D. Oxidative stress with the production of reactive oxygen species and cytokine-mediated inflammation represents the main hallmarks of chronic stress. ROS production and pro-inflammatory cytokines represent the main hallmarks of stress-related disorders, and therefore, the use of natural antioxidant and anti-inflammatory substances (nutraceuticals) may offer an alternative therapeutic approach to combat stress-related T2D. Single or combined administration of nutraceuticals would be very beneficial in targeting the neuro-endocrine-immune axis, thus, regulating major pathways involved in T2D onset. However, more clinical trials are needed to establish the effectiveness of nutraceutical treatment, dosage, time of administration and the most favorable combinations of compounds. Therefore, in view of their antioxidant and anti-inflammatory properties, the use of natural products or nutraceuticals for the treatment of stress-related diseases, even including T2D, will be discussed. Several evidences suggest that chronic stress represents one of the main factors responsible for the outcome of T2D.

Affective reactivity to daily stressors and immune cell gene expression in the MIDUS study

Affective reactivity to stress is a person-level measurement of how well an individual copes with daily stressors. A common method of measuring affective reactivity entails the estimation of within-person differences of either positive or negative affect on days with and without stressors present. Individuals more reactive to common stressors, as evidenced by affective reactivity measurements, have been shown to have increased levels of circulating pro-inflammatory markers. While affective reactivity has previously been associated with inflammatory markers, the upstream mechanistic links underlying these associations are unknown. Using data from the Midlife in the United States (MIDUS) Refresher study (N = 195; 52% female; 84% white), we quantified daily stress processes over 10 days and determined individuals' positive and negative affective reactivities to stressors. We then examined affective reactivity association with peripheral blood mononuclear cell (PBMC) gene expression of the immune-related conserved transcriptional response to adversity. Results indicated that individuals with a greater decrease in positive affect to daily stressors exhibited heightened PBMC JUNB expression after Bonferroni corrections (p-adjusted < 0.05). JUNB encodes a protein that acts as a transcription factor which regulates many aspects of the immune response, including inflammation and cell proliferation. Due to its critical role in the activation of macrophages and maintenance of CD4+ T-cells during inflammation, JUNB may serve as a potential upstream mechanistic target for future studies of the connection between affective reactivity and inflammatory processes. Overall, our findings provide evidence that affective reactivity to stress is associated with levels of immune cell gene expression.

Lessons from lonely flies: Molecular and neuronal mechanisms underlying social isolation

Animals respond to changes in the environment which affect their internal state by adapting their behaviors. Social isolation is a form of passive environmental stressor that alters behaviors across animal kingdom, including humans, rodents, and fruit flies. Social isolation is known to increase violence, disrupt sleep and increase depression leading to poor mental and physical health. Recent evidences from several model organisms suggest that social isolation leads to remodeling of the transcriptional and epigenetic landscape which alters behavioral outcomes. In this review, we explore how manipulating social experience of fruit fly Drosophila melanogaster can shed light on molecular and neuronal mechanisms underlying isolation driven behaviors. We discuss the recent advances made using the powerful genetic toolkit and behavioral assays in Drosophila to uncover role of neuromodulators, sensory modalities, pheromones, neuronal circuits and molecular mechanisms in mediating social isolation. The insights gained from these studies could be crucial for developing effective therapeutic interventions in future.

Antagonism of the brain P2X7 ion channel attenuates repeated social defeat induced microglia reactivity, monocyte recruitment and anxiety-like behavior in male mice

Chronic stress is linked to increased anxiety. Repeated social defeat (RSD) in mice causes anxiety that is dependent on activated neurons, reactive microglia, and accumulation of monocytes in the brain. This response requires interactions between the immune system and central nervous system (CNS). Neuronal activation within threat appraisal regions is a key response to RSD, however, it is unclear how microglia become activated. One potential explanation is that microglia express a purinergic non-selective ligand gated adenosine-triphosphate (ATP) receptor 7 (P2X7). Activation of P2X7 promotes the release of chemokines and cytokines, and recruitment of monocytes to the brain. Thus, the purpose of this study was to determine if a novel P2X7 antagonist blocked neuronal and microglia interactions and the corresponding anxiety following RSD. Male mice were administered (i.p.) a P2X7 antagonist, JNJ-54471300, prior to each cycle of RSD. Fourteen hours after RSD, behavioral deficits including social avoidance and anxiety-like were determined. Moreover, several immune parameters were assessed. RSD caused neuronal activation in stress-responsive regions, monocyte production and release, splenomegaly, and social avoidance. These parameters were unaffected by P2X7 antagonism. RSD-associated proportional area of Iba-1+ microglia, monocyte accumulation in the brain, IL-1β mRNA expression in enriched myeloid cells, plasma IL-6, and anxiety-like behavior were ameliorated by P2X7 antagonism. Gene expression analysis in the hippocampus and amygdala showed regional specific responses to RSD and some were reversed with P2X7 antagonism. Overall, blocking P2X7 activation attenuated RSD-induced microglia reactivity with corresponding reduction in neuroinflammation, monocyte accumulation, and anxiety-like behavior in male mice.

Social stress induces autoimmune responses against the brain

Clinical studies have revealed a high comorbidity between autoimmune diseases and psychiatric disorders, including major depressive disorder (MDD). However, the mechanisms connecting autoimmunity and depression remain unclear. Here, we aim to identify the processes by which stress impacts the adaptive immune system and the implications of such responses to depression. To examine this relationship, we analyzed antibody responses and autoimmunity in the chronic social defeat stress (CSDS) model in mice, and in clinical samples from patients with MDD. We show that socially stressed mice have elevated serum antibody concentrations. We also confirm that social stress leads to the expansion of specific T and B cell populations within the cervical lymph nodes, where brain-derived antigens are preferentially delivered. Sera from stress-susceptible (SUS) mice exhibited high reactivity against brain tissue, and brain-reactive immunoglobulin G (IgG) antibody levels positively correlated with social avoidance behavior. IgG antibody concentrations in the brain were significantly higher in SUS mice than in unstressed mice, and positively correlated with social avoidance. Similarly, in humans, increased peripheral levels of brain-reactive IgG antibodies were associated with increased anhedonia. In vivo assessment of IgG antibodies showed they largely accumulate around blood vessels in the brain only in SUS mice. B cell-depleted mice exhibited stress resilience following CSDS, confirming the contribution of antibody-producing cells to social avoidance behavior. This study provides mechanistic insights connecting stress-induced autoimmune reactions against the brain and stress susceptibility. Therapeutic strategies targeting autoimmune responses might aid in the treatment of patients with MDD featuring immune abnormalities.

Trained immunity in atherosclerotic cardiovascular disease

Trained immunity, also known as innate immune memory, is a persistent hyper-responsive functional state of innate immune cells. Accumulating evidence implicates trained immunity as an underlying mechanism of chronic inflammation in atherosclerotic cardiovascular disease. In this context, trained immunity is induced by endogenous atherosclerosis-promoting factors, such as modified lipoproteins or hyperglycaemia, causing broad metabolic and epigenetic reprogramming of the myeloid cell compartment. In addition to traditional cardiovascular risk factors, lifestyle factors, including unhealthy diets, sedentary lifestyle, sleep deprivation and psychosocial stress, as well as inflammatory comorbidities, have been shown to activate trained immunity-like mechanisms in bone marrow haematopoietic stem cells. In this Review, we discuss the molecular and cellular mechanisms of trained immunity, its systemic regulation through haematopoietic progenitor cells in the bone marrow, and the activation of these mechanisms by cardiovascular disease risk factors. We also highlight other trained immunity features that are relevant for atherosclerotic cardiovascular disease, including the diverse cell types that show memory characteristics and transgenerational inheritance of trained immunity traits. Finally, we propose potential strategies for the therapeutic modulation of trained immunity to manage atherosclerotic cardiovascular disease.

Inflammation and emotion regulation: a narrative review of evidence and mechanisms in emotion dysregulation disorders

Emotion dysregulation (ED) describes a difficulty with the modulation of which emotions are felt, as well as when and how these emotions are experienced or expressed. It is a focal overarching symptom in many severe and prevalent neuropsychiatric diseases, including bipolar disorders (BD), attention deficit/hyperactivity disorder (ADHD), and borderline personality disorder (BPD). In all these disorders, ED can manifest through symptoms of depression, anxiety, or affective lability. Considering the many symptomatic similarities between BD, ADHD, and BPD, a transdiagnostic approach is a promising lens of investigation. Mounting evidence supports the role of peripheral inflammatory markers and stress in the multifactorial aetiology and physiopathology of BD, ADHD, and BPD. Of note, neural circuits that regulate emotions appear particularly vulnerable to inflammatory insults and peripheral inflammation, which can impact the neuroimmune milieu of the central nervous system. Thus far, few studies have examined the link between ED and inflammation in BD, ADHD, and BPD. To our knowledge, no specific work has provided a critical comparison of the results from these disorders. To fill this gap in the literature, we review the known associations and mechanisms linking ED and inflammation in general, and clinically, in BD, ADHD, and BD. Our narrative review begins with an examination of the routes linking ED and inflammation, followed by a discussion of disorder-specific results accounting for methodological limitations and relevant confounding factors. Finally, we critically discuss both correspondences and discrepancies in the results and comment on potential vulnerability markers and promising therapeutic interventions.

Association between adult food insecurity and self-reported asthma in the United States: NHANES 2003-2018

OBJECTIVE

Asthma is a chronic disease of the lungs. The development of asthma is related to various risk factors. Food insecurity is a critical social determinant of health, although there is little information on the association between adult food insecurity and asthma. The purpose of this study is to explore the potential correlation in US adults.

METHODS

The study population data were extracted from NHANES 2003-2018. Food insecurity was measured using the USDA FSSM and categorized as full, marginal, low, or very low food security. The assessment of self-reported asthma was determined by self-report questionnaires. The self-reported positive outcomes were that participants had asthma and a history of asthma attacks and asthma-related ER visits in the past year. We developed two multivariate logistic regression models. Stratified analyses were performed by gender and age.

RESULTS

A total of 38,077 participants were considered in our final analysis. Compared to participants with FFS, the ORs (95% CIs) for asthma were 1.16 (1.00-1.33), 1.42 (1.23-1.64), and 1.56 (1.34-1.80) for participants with MFS, LFS, and VLFS, respectively (Model II). Additionally, after full adjustment, individuals with VLFS had 49% greater risks of asthma attacks (OR = 1.49; 95% CI 1.13-1.97). The ORs (95% CIs) for asthma-related ER visits were 1.59 (1.14-2.23) and 1.98 (1.36-2.87) for participants with LFS and VLFS, respectively (Model II). The positive correlations remained robust when stratified by gender and age.

CONCLUSION

Our research showed that food insecurity among US adults was associated with asthma, asthma attacks, and asthma-related ER visits.

Daily heart rate variability biofeedback training decreases locus coeruleus MRI contrast in younger adults in a randomized clinical trial

As an arousal hub region in the brain, the locus coeruleus (LC) has bidirectional connections with the autonomic nervous system. Magnetic resonance imaging (MRI)-based measures of LC structural integrity have been linked to cognition and arousal, but less is known about factors that influence LC structure and function across time. Here, we tested the effects of heart rate variability (HRV) biofeedback, an intervention targeting the autonomic nervous system, on LC MRI contrast and sympathetic activity. Younger and older participants completed daily HRV biofeedback training for five weeks. Those assigned to an experimental condition performed biofeedback involving slow, paced breathing designed to increase heart rate oscillations, whereas those assigned to a control condition performed biofeedback to decrease heart rate oscillations. At the pre- and post-training timepoints, LC contrast was assessed using turbo spin echo MRI scans, and RNA sequencing was used to assess cAMP-responsive element binding protein (CREB)-regulated gene expression in circulating blood cells, an index of sympathetic nervous system signaling. We found that left LC contrast decreased in younger participants in the experimental group, and across younger participants, decreases in left LC contrast were related to the extent to which participants increased their heart rate oscillations during training. Furthermore, decreases in left LC contrast were associated with decreased expression of CREB-associated gene transcripts. On the contrary, there were no effects of biofeedback on LC contrast among older participants in the experimental group. These findings provide novel evidence that in younger adults, HRV biofeedback involving slow, paced breathing can decrease both LC contrast and sympathetic nervous system signaling.

Pheromone of grouped female mice impairs genome stability in male mice through stress-mediated pathways

Population density is known to affect the health and survival of many species, and is especially important for social animals. In mice, living in crowded conditions results in the disruption of social interactions, chronic stress, and immune and reproductive suppression; however, the underlying mechanisms remain unclear. Here, we investigated the role of chemosignals in the regulation of mouse physiology and behavior in response to social crowding. The pheromone 2,5-dimethylpyrazine (2,5-DMP), which is released by female mice in crowded conditions, induced aversion, glucocorticoid elevation and, when chronic, resulted in reproductive and immune suppression. 2,5-DMP olfaction induced genome destabilization in bone marrow cells in a stress-dependent manner, providing a plausible mechanism for crowding-induced immune dysfunction. Interestingly, the genome-destabilizing effect of 2,5-DMP was comparable to a potent mouse stressor (immobilization), and both stressors led to correlated expression changes in genes regulating cellular stress response. Thus, our findings demonstrate that, in mice, the health effects of crowding may be explained at least in part by chemosignals and also propose a significant role of stress and genome destabilization in the emergence of crowding effects.