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• Psychological stress is a crucial factor in the development of many skin diseases. • Psychological stress can worsen skin diseases and affect patients' quality of life. • Stress impacts skin diseases through the HPA axis, SNS, and neuropeptides. Psychological stress is a crucial factor in the development of many skin diseases, and the stigma caused by skin disorders may further increase the psychological burden, forming a vicious cycle of psychological stress leading to skin diseases. Therefore, understanding the relationship between stress and skin diseases is necessary. The skin, as the vital interface with the external environment, possesses its own complex immune system, and the neuroendocrine system plays a central role in the stress response of the body. Stress-induced alterations in the immune system can also disrupt the delicate balance of immune cells and inflammatory mediators in the skin, leading to immune dysregulation and increased susceptibility to various skin diseases. Stress can also affect the skin barrier function, impair wound healing, and promote the release of pro-inflammatory cytokines, thereby exacerbating existing skin diseases such as psoriasis, atopic dermatitis, acne, and urticaria. In the present review, we explored the intricate relationship between stress and skin diseases from a neuroendocrine-immune interaction perspective. We explored the occurrence and development of skin diseases in the context of stress, the stress models for skin diseases, the impact of stress on skin function and diseases, and relevant epidemiological studies and clinical trials. Understanding the relationship between stress and skin diseases from a neuroendocrine-immune interaction perspective provides a comprehensive framework for targeted interventions and new insights into the diagnosis and treatment of skin diseases. [ABSTRACT FROM AUTHOR]

• Epidemiologic data support a link between PTSD and SLE-risk. • There is evidence of inflammation and immune system dysregulation in PTSD. • Inflammation that accompanies PTSD may fan the flames of smoldering SLE. • PTSD may be responsible for some of the disparities in SLE incidence and outcomes. Systemic lupus erythematosus (SLE) is a heterogeneous, multisystem autoimmune disorder characterized by unpredictable disease flares. Although the pathogenesis of SLE is complex, an epidemiologic link between posttraumatic stress disorder (PTSD) and the development of SLE has been identified, suggesting that stress-related disorders alter the susceptibility to SLE. Despite the strong epidemiologic evidence connecting PTSD and SLE, gaps remain in our understanding of how the two may be connected. Perturbations in the autonomic nervous system, neuroendocrine system, and at the genomic level may cause and sustain immune dysregulation that could lower the threshold for the development and propagation of SLE. We first describe shared risk factors for SLE and PTSD. We then describe potential biological pathways which may facilitate excessive inflammation in the context of PTSD. Among those genetically predisposed to SLE, systemic inflammation that accompanies chronic stress may fan the flames of smoldering SLE by priming immune pathways. Further studies on the connection between trauma and inflammation will provide important data on pathogenesis, risk factors, and novel treatments for SLE. [ABSTRACT FROM AUTHOR]

• It has been shown that acute stress alters immune cell levels (i.e., monocytes) in rodents. • Here it is shown that acute stress increases monocyte levels in healthy females. • This is paired with alterations in the expression of specific receptors on monocytes. 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. [ABSTRACT FROM AUTHOR]

• Poor diet in early development can lead to long-term negative metabolic and cognitive outcomes. • It also impairs microglial responses to immune challenge and to learning. • These effects are likely due to changes in the brain immune system and the HPA axis. • These data highlight the importance of dietary choices in early life. The early life period is crucially important to how the individual develops, and environmental and lifestyle challenges during this time can lead to lasting programming effects on the brain and immune system. In particular, poor diet in early development can lead to long-term negative metabolic and cognitive outcomes, with those who over-eat in early development being at risk of obesity and poor learning and memory throughout their adult lives. Current research has identified a neuroinflammatory component to this metabolic and cognitive programming that can potentially be manipulated to restore a healthy phenotype. Thus, early life over-feeding in a rat model leads to microglial priming and an exacerbated microglial response to immune challenge when the rats reach adulthood. Microglial responses to a learning task are also impaired. To specifically investigate the role of microglia in these programming effects our group has developed a novel transgenic rat with a diphtheria toxin receptor insertion in the promoter region for the Cx3cr1 gene, expressed on microglia and monocytes; allowing us to conditionally ablate microglia throughout the brain. With this model we reveal that microglia have a direct role in regulating feeding behavior and modifying cognition, but are not likely to be the sole mechanism by which early life overfeeding confers lasting neuroimmune and cognitive effects. Additional work implicates changes to the hypothalamic-pituitary-adrenal axis in this. Together these data highlight the importance of dietary choices in early life and the potential for positive interventions targeting the neuroimmune and neuroendocrine stress systems to reverse such programming damage. [ABSTRACT FROM AUTHOR]

• Several stress-mediated pathways relevant to the formation of brain metastases have been identified. • Stress-induced activation of the neuroendocrine system, noradrenergic pathways and β-adrenergic signaling contribute to inflammation, impaired cellular immune response, and tumor angiogenesis. • Pharmacological blockade of stress- and inflammatory pathways, and immune stimulation, may provide a viable pharmacological strategy for suppressing many of the pathways through which the SNS can stimulate tumor progression and the formation of brain metastasis. Chronic stress can promote tumor growth and progression through immunosuppressive effects and bi-directional interactions between tumor cells and their microenvironment. β-Adrenergic receptor signaling plays a critical role in mediating stress-related effects on tumor progression. Stress-related mechanisms that modulate the dissemination of tumor cells to the brain have received scant attention. Brain metastases are highly resistant to chemotherapy and contribute considerably to morbidity and mortality in various cancers, occurring in up to 20% of patients in some cancer types. Understanding the mechanisms promoting brain metastasis could help to identify interventions that improve disease outcomes. In this review, we discuss biobehavioral, sympathetic, neuroendocrine, and immunological mechanisms by which chronic stress can impact tumor progression and metastatic dissemination to the brain. The critical role of the inflammatory tumor microenvironment in tumor progression and metastatic dissemination to the brain, and its association with stress pathways are delineated. We also discuss translational implications for biobehavioral and pharmacological interventions. [ABSTRACT FROM AUTHOR]

• Germ-free mice have increased plasma adrenaline and noradrenaline levels. • Colonisation of the microbiota normalises adrenaline levels. • Germ-free mice have decreased myeloid cell levels, which is rescued by microbiota colonisation. • Acute stress modulates myeloid cell numbers in a cell-type-specific manner. • Acute stress-induced changes in myeloid cell numbers are affected by the microbiota. There has been a growing recognition of the involvement of the gastrointestinal microbiota in the development of stress-related disorders. Acute stress leads to activation of neuroendocrine systems, which in turn orchestrate a large-scale redistribution of innate immune cells. Both these response systems are independently known to be primed by the microbiota, even though much is still unclear about the role of the gastrointestinal microbiota in acute stress-induced immune activation. In this study, we investigated whether the microbiota influences acute stress-induced changes in innate immunity using conventionally colonised mice, mice devoid of any microbiota (i.e. germ-free, GF), and colonised GF mice (CGF). We also explored the kinetics of stress-induced immune cell mobilisation in the blood, the spleen and mesenteric lymph nodes (MLNs). Mice were either euthanised prior to stress or underwent restraint stress and were then euthanised at various time points (i.e. 0, 45- and 240-minutes) post-stress. Plasma adrenaline and noradrenaline levels were analysed using ELISA and immune cell levels were quantified using flow cytometry. GF mice had increased baseline levels of adrenaline and noradrenaline, of which adrenaline was normalised in CGF mice. In tandem, GF mice had decreased circulating levels of LY6Chi and LY6Cmid, CCR2+ monocytes, and granulocytes, but not LY6C−, CX3CR1+ monocytes. These deficits were normalised in CGF mice. Acute stress decreased blood LY6Chi and LY6Cmid, CCR2+ monocytes while increasing granulocyte levels in all groups 45 min post-stress. However, only GF mice showed stress-induced changes in LY6Chi monocytes and granulocytes 240 min post-stress, indicating impairments in the recovery from acute stress-induced changes in levels of specific innate immune cell types. LY6C−, CX3CR1+ monocytes remained unaffected by stress, indicating that acute stress impacts systemic innate immunity in a cell-type-specific manner. Overall, these data reveal novel cell-type-specific changes in the innate immune system in response to acute stress, which in turn are impacted by the microbiota. In conclusion, the microbiota influences the priming and recovery of the innate immune system to an acute stressor and may inform future microbiota-targeted therapeutics aimed at modulating stress-induced immune activation in stress-related disorders. [ABSTRACT FROM AUTHOR]

Exposure to psychosocial stress can have a profound impact on immune reactivity and health mediated by hypothalamic–pituitaryadrenal (HPA) axis activation. However, current knowledge regarding the mechanisms involved in cross-sensitization between stress and the immune system is limited. Here, we investigated the effects of a single social isolation followed by repeated oral Escherichia coli ( E. coli ) applications on cortisol, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), haptoglobin and C-reactive protein (CRP) concentrations in the blood; on clinical signs of disease; and on mRNA expression of the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11β-hydroxysteroid dehydrogenase 1 and 2 (11β-HSD1 and 11β-HSD2), TNF-α and IL-6 in the hypothalamus, prefrontal cortex (PFC) and spleen of 7-, 21- and 35-day-old piglets. Additionally, the protein levels of splenic TNF-α and IL-6 were analyzed. Non-isolated, E. coli -challenged piglets served as a control. Social isolation for 4 h induced a rise in the plasma cortisol concentrations immediately after social treatment and after repeated E. coli applications in isolated compared to non-isolated piglets. The circulating TNF-α concentration was not affected by social treatment. Furthermore, previously isolated piglets showed a higher frequency of signs of disease in response to E. coli challenge than non-isolated piglets, while the haptoglobin and CRP concentrations did not significantly differ between social treatments. In the brain, 11β-HSD1, 11β-HSD2 and IL-6 mRNA expression in the hypothalamus and GR, and 11β-HSD1 and 11β-HSD2 mRNA expression in the PFC were higher in isolated, E. coli -challenged piglets than in the corresponding controls. Moreover, isolated piglets also displayed higher MR, 11β-HSD1 and IL-6 mRNA expression levels and TNF-α concentrations in the spleen. The stress-induced alterations in the hypothalamus and spleen were particularly pronounced in younger piglets. The present findings may contribute to a better understanding of the complex interplay between early psychological stress and an increased risk of disease and might also have implications on aspects of the health and welfare of farm animals and humans. [ABSTRACT FROM AUTHOR]

The most common Parkinson’s disease (PD) mutation is the gain-of-function LRRK2 G2019S variant, which has also been linked to inflammatory disease states. Yet, little is known of the role of G2019S in PD related complex behavioral or immune/hormonal processes in response to inflammatory/toxicant challenges. Hence, we characterized the behavioral, neuroendocrine-immune and central monoaminergic responses in G2019S overexpressing mutants following systemic interferon-gamma (IFN-γ) or lipopolysaccharide (LPS) administration. Although LPS markedly (and IFN-γ modestly in some cases) increased cytokine and corticosterone levels, while inducing pronounced sickness and home-cage activity deficits, the G2019S mutation had no effect on these parameters. No differences were observed with regards to brain microglia with the acute LPS injection, regardless of genotype. Nor did the G2019S mutation influence neurotransmitter levels within the medial prefrontal cortex or paraventricular nucleus of the hypothalamus. However, the LRRK2 G2019S transgenic mice did have altered monoamine levels within the striatum and hippocampus. Indeed, G2019S mice had altered basal levels and turnover of dopamine within the striatum, along with changes in hippocampal serotonin and norepinephrine activity in response to LPS and IFN-γ. The present findings suggest the importance of murine G2019S in hippocampal and striatal neurotransmission, but that the transgene didn’t appear to be involved in functional behavioral and stress-like hormonal and cytokine changes provoked by inflammatory insults. [ABSTRACT FROM AUTHOR]

Objectives Health outcomes, including chronic disease and mortality, attributed to or associated with alcohol abuse are discrepant between African Americans and Whites. To date, the topic is not fully understood and few studies conducted have used biomarker indicators of health. We investigated whether the association between alcohol abuse and biomarkers of the neuroendocrine system vary between black or African American and White respondents aged 34–84 from the Midlife in the United States Study (MIDUS) II (2004–2006) ( n = 1129). Alcohol abuse was assessed with a modified version of the Michigan Alcohol Screening Test. Ordinary least squared (OLS) regression was used to evaluate whether race moderated the associations between alcohol abuse and four biomarkers—urinary cortisol and serum dehydroepiandrosterone sulfate (DHEA-S), epinephrine and norepinephrine—and two composite summary scores, each consisting of two components that characterize the hypothalamic pituitary adrenal (HPA)-axis and sympathetic nervous systems (SNS), respectively. Covariates included age, sex, education, income, current drinking, smoking, exercise, fast food consumption, heart disease, blood pressure, diabetes, body mass index, medication use, anxiety/depression, sleep duration, and cholesterol markers. Race significantly moderated the associations between alcohol abuse and norepinephrine concentration (χ 2 [1] = 4.48, p = 0.034) and the SNS composite score (χ 2 [1] = 5.83, p = 0.016). Alcohol abuse was associated with higher mean norepinephrine levels (b = 0.26, standard error (SE) = 0.12, p = 0.034) and SNS composite score (b = 0.23, SE = 0.11, p = 0.016) for African Americans compared to Whites. Interestingly, for Whites a paradoxical association between alcohol abuse, norepinephrine and SNS levels was observed; those who abused alcohol had lower mean norepinephrine levels than non-abusers. Race differences in neuroendocrine response could be biological pathways that contribute the excess risk of chronic disease and mortality attributed to alcohol abuse among African Americans compared to Whites. Replication of these analyses in larger cohorts are warranted in addition to further studies of underlying mechanisms among Blacks and Whites separately. [ABSTRACT FROM AUTHOR]

There is a growing emphasis on the relationship between the microorganisms inhabiting the gut (gastrointestinal microbiota) and human health. The emergence of a microbiota-gut-brain axis to describe the complex networks and relationship between the gastrointestinal microbiota and host reflects the major influence this environment may have in brain health and disorders of the central nervous system (CNS). Bidirectional communication between the microbiota and the CNS occurs through autonomic, neuroendocrine, enteric, and immune system pathways. Potential neurobiological mechanisms through which disruptions in this network may impact health and disease include hypothalamic-pituitary-adrenal (HPA)-axis activation, and altered activity of neurotransmitter and immune systems. Perturbations of the gut microbial community have already been implicated in multiple host diseases such as obesity, diabetes, and inflammation, while recent evidence suggests a potential role of the microbiota-gut-brain axis in neuropsychiatric disorders, such as depression and anxiety. Here, we review the current literature related to the influence of the gut microbial community on central nervous system function, with a specific focus on anxiety and depressive symptoms. The role of stress and stress-mediated changes in autonomic, neuroendocrine, immune, and neurotransmitter systems are examined, followed by a discussion of the role of the microbiota in novel gastrointestinal-based treatment options for the prevention and treatment of brain-based disorders such as anxiety and depression. [ABSTRACT FROM AUTHOR]

Activation of the hypothalamo-pituitary-adrenal (HPA) axis by inflammatory stressors (e.g., bacterial lipopolysaccharide) is thought to involve vascular transduction of circulating cytokines, with perivascular macrophages (PVMs) along with endothelia, effecting activation of HPA control circuitry via inducible (cyclooxygenase-2- or COX-2-dependent) prostaglandin synthesis. To test the stressor-specificity of this mechanism, we examined whether ablation of PVMs or pharmacologic blockade of COX activity affected HPA responses to a representative emotional stressor, restraint. Exposing rats to a single 30 min acute restraint episode provoked increased plasma levels of at least one proinflammatory cytokine, IL-6, microglial activation and multiple indices of cerebrovascular activation, including COX-2 expression and increased brain prostaglandin E2 levels at 0-2 h after stress. Pretreatment with the nonselective COX inhibitor, indomethacin, either icv (10 μg in 5 μl) or iv (1 mg/kg) significantly reduced restraint-induced Fos expression in the paraventricular hypothalamic nucleus (PVH) by 45%, relative to vehicle-injected controls. A 75% reduction of the PVH activational response was seen in rats exposed to acute restraint 5-7 days after ablation of brain PVMs by icv injection of liposomes encapsulating the bisphosphonate drug, clodronate. Basal plasma levels of ACTH and corticosterone were not altered in clodronate liposome-injected rats, but the peak magnitude of restraint-induced HPA secretory responses was substantially reduced, relative to animals pretreated with saline-filled liposomes. These findings support an unexpectedly prominent role for inducible prostaglandin synthesis by PVMs in HPA responses to acute restraint, a prototypic emotional stressor. [ABSTRACT FROM AUTHOR]

The default mode network (DMN) encompasses brain systems that exhibit coherent neural activity at rest. DMN brain systems have been implicated in diverse social, cognitive, and affective processes, as well as risk for forms of dementia and psychiatric disorders that associate with systemic inflammation. Areas of the anterior cingulate cortex (ACC) and surrounding medial prefrontal cortex (mPFC) within the DMN have been implicated specifically in regulating autonomic and neuroendocrine processes that relate to systemic inflammation via bidirectional signaling mechanisms. However, it is still unclear whether indicators of inflammation relate directly to coherent resting state activity of the ACC, mPFC, or other areas within the DMN. Accordingly, we tested whether plasma interleukin (IL)-6, an indicator of systemic inflammation, covaried with resting-state functional connectivity of the DMN among 98 adults aged 30-54 (39% male; 81% Caucasian). Independent component analyses were applied to resting state fMRI data to generate DMN connectivity maps. Voxel-wise regression analyses were then used to test for associations between IL-6 and DMN connectivity across individuals, controlling for age, sex, body mass index, and fMRI signal motion. Within the DMN, IL-6 covaried positively with connectivity of the sub-genual ACC and negatively with a region of the dorsal medial PFC at corrected statistical thresholds. These novel findings offer evidence for a unique association between a marker of systemic inflammation (IL-6) and ACC and mPFC functional connectivity within the DMN, a network that may be important for linking aspects of immune function to psychological and behavioral states in health and disease. [ABSTRACT FROM AUTHOR]

Abstract: Acupuncture is the most popular component of traditional Chinese medicine in western countries, which has been widely used in the treatment of numerous medical conditions, e.g., pain, emesis or asthma. However, the effects of acupuncture on neuroendocrine and immune functions in humans remain unclear. Therefore, the present study was performed to analyse whether acupuncture treatment affects leukocyte circulation as well as plasma levels of cortisol and norepinephrine in humans. Ten healthy young male subjects were enrolled in a randomized single-blind two-period crossover study. Each period contained three sessions of either acupuncture or sham acupuncture (placebo) treatment. After randomisation, the group 1 (n =5) received acupuncture treatment at acu-points ST36, LI11, SP10, and GV14, while sham acupuncture was performed for group 2 (n =5). Two weeks later, each group received the alternative treatment. Blood samples were taken before needling, 10min after, and 30min after removing the needles in the first and the third session. In addition, blood pressure and heart rate were determined simultaneously. Although acupuncture treatment did not affect leukocyte circulation in peripheral blood after the first session, we observed a significant decrease in leukocyte and lymphocyte values after the third session. In contrast, cortisol and norepinephrine plasma levels remained unchanged by acupuncture. These data indicate that repeated acupuncture treatment can affect leukocyte circulation in healthy humans by still unknown mechanisms. [Copyright &y& Elsevier]

We have previously reported that flatter cortisol slopes and higher nocturnal cortisol pre-surgery are associated with shorter survival times in ovarian cancer. Diurnal cortisol profiles normalize after completion of chemotherapy, and parallel changes in plasma IL-6, suggesting that successful primary treatment is linked with decreases in inflammation. In this study, we examined cortisol profiles in 5-year ovarian cancer survivors and associations with psychosocial factors. Participants were 30 survivors (19 early-stage, 11 advanced-stage at diagnosis) who had previously participated in our prospective study. They were re-contacted at least 5 years (mean = 6.16 years) post-diagnosis at which time they completed psychosocial assessments and collected salivary cortisol upon waking, at 4-6pm, and at bedtime for 3 days. Adjusting for age, the cortisol profiles of 5-year survivors approximated those of healthy women, although survivors had slightly higher night cortisol ( p = 0.088 ) and flatter diurnal slopes ( p = . 096 ). Greater cumulative lifetime stress burden (beta = 0.54, p = 0.008 ), including both acute events (beta = 0.50, p = 0.016) and chronic difficulties (beta = 0.48, p = 0.02), and greater concurrent depression (beta = 0.41, p = 0.019) were each associated with flatter cortisol slopes at 5 years, adjusting for age and stage. These findings suggest that although cortisol profiles have largely normalized in long term survivors, chronic stress and mood are still linked to diurnal cortisol. As cortisol can impair chemotherapeutic response and can reflect tumor-derived inflammation, these findings may have clinical relevance. [ABSTRACT FROM AUTHOR]

Adversities in childhood are suggested to affect neuroendocrine pathways that in turn increases the risk of elevated inflammation and inflammatory disease in adulthood. During pregnancy, maternal immune activation has been linked with poor pregnancy outcome and risk for neurodevelopmental disease in the offspring. This study investigates childhood experience of parental separation and current socio economic position in relation to adult immune reaction at the event of giving birth, term or preterm. Sixty-four women were sampled during delivery and post-partum. Serum levels of Interleukin (IL)-6 were analyzed from maternal (preterm n = 27, term n = 37) and cord blood (preterm n = 23, term n = 32). Information on annual income and childhood family situation was collected through questionnaires. Multiple linear regression analyses using log transformed IL-6 data, showed associations between childhood experience of parental separations and elevated levels of maternal IL-6 from labor and post-partum, p < .05 in both preterm and term delivery. Annual income level was negatively associated with maternal labor IL-6 levels as well as with umbilical cord levels; p < .05. The results of this study indicate that early experiences could lead to sensitization of the adult immune system at time of giving birth. Future studies might clarify the importance of these findings regarding inflammation during pregnancy and pregnancy outcomes. [ABSTRACT FROM AUTHOR]