Neuroimmunology of stress: skin takes center stage

Immune links in comorbid depression and psoriasis: A narrative mini-review and perspective

Evidence suggests a bidirectional association between psoriasis and depression, which is considered to reflect complex neuroimmunological and psychosocial interactions. Despite an early interest in the brain-skin axis and the role of stress in psoriasis immunopathogenesis, there is ongoing limited preclinical and clinical research into the inflammatory links between depression and psoriasis. Existing findings for serum inflammatory markers of depression in psoriasis are inconsistent and do not fully align with those in the general population, while brain imaging evidence is scarce and has not confirmed direct brain involvement in the systemic inflammation of psoriasis. The present paper reviews the available literature on the immune interplay of psoriasis with depression, highlights the significance of further work in the field and proposes avenues for future research.

Ectoin attenuates cortisone-induced skin issues by suppression GR signaling and the UVB-induced overexpression of 11β-HSD1

BACKGROUND

Accelerated pace of modern work and lifestyles subject individuals to various external and psychological stressors, which, in turn, can trigger additional stress through visible signs of fatigue, hair loss, and obesity. As the primary stress hormone affecting skin health, cortisol connects to the glucocorticoid receptor (GR) to aggravate skin issues induced by stress. This activation depends on the expression of 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) in skin cells, which locally converts cortisone-produced by the central and peripheral hypothalamic-pituitary-adrenal axis-into its active form.

METHODS

Our study delves deeper into stress's adverse effects on the skin, including the disruption of keratinocyte structural proteins, the loss of basement membrane proteins, and the degradation of collagen.

RESULTS

Remarkably, we discovered that Ectoin, an amino acid derivative obtained from halophilic bacteria, is capable of mitigating the inhibitory impacts of cortisone on the expression of cutaneous functional proteins, including involucrin, loricrin, laminin-5, and claudin-1. Moreover, Ectoin reduces the suppressive effect of stress on collagen and hyaluronic acid synthesis by impeding GR signal transduction. Additionally, Ectoin counterbalances the UVB-induced overexpression of 11β-HSD1, thereby diminishing the concentration of endogenous glucocorticoids.

CONCLUSION

Our findings illuminate the significant potential of Ectoin as a preventative agent against stress-induced skin maladies.

Trauma and sensory systems: Biological mechanisms involving the skin and the 17q21 gene cluster

Childhood trauma experience increases risk for neuropsychiatric and neurodevelopmental disorders, including posttraumatic stress disorder (PTSD), autism spectrum disorders (ASDs), and attention deficit/hyperactivity disorder (ADHD). While the biological mechanisms connecting adverse experiences with later disease presentation are not clear, the concept of Gene x Environment x Development (GxExD) interactions has significant implications for improving our understanding of these diseases. We recently utilized this approach in a study where we found that women exposed to interpersonal violence trauma (the E) uniquely during adolescence (the D), but not childhood or adulthood, had novel protein biomarkers (the G) associated with a sensory cell system in the skin, Merkel cells. Merkel cell mechanosensory signaling is important in gentle and social touch, inflammation-induced pain, and the skin's neuroendocrine stress response. Further, keratinocyte-derived Merkel cell final maturation occurs during the identified vulnerable period of adolescence. Interestingly, many of the genes identified in our study belong to a known 17q21 gene cluster, suggesting an identifiable location in the genome permanently altered by adolescent trauma. These results form a potential functional link between mechanosensory Merkel cells and the pathology and sensory symptomatology in PTSD. Future research directions could identify specific mechanisms involved in tactile alterations following trauma in hopes of revealing additional biomarkers and potentially leading to novel tactile-involved therapies (e.g., massage, electroacupuncture, or focused ultrasound).

Global, regional, and national levels and trends in burden of urticaria: A systematic analysis for the Global Burden of Disease study 2019

Background

Urticaria places a significant burden on individuals and society due to its widespread nature. The aim of this study was to evaluate the burden of urticaria in different regions and nations by analysing data from the Global Burden of Disease study 2019 (GBD 2019), with the goal of providing information to health care policymakers.

Methods

By utilising data from the GBD 2019 database, this study analysed metrics such as incidence, prevalence, disability-adjusted life years (DALYs), age-standardised rate (ASR), and estimated annual percentage changes (EAPC) globally and across 204 countries and regions. The data was further stratified by age, sex, and sociodemographic index (SDI).

Results

In 2019, global incidence cases, prevalence cases, and overall disease burden as measured by DALYs all increased. The distribution of the burden exhibited marked geographical heterogeneity. At the regional level, the burden is highest in Central and Eastern Europe and Central Asia, with the strongest growth in South Asia, compared with a decline in the high-income Asia Pacific. At the country level, Nepal reports the highest burden of urticaria, while Portugal has the lowest. Gender and age analyses showed that the burden of urticaria is higher in females than in males, with urticaria cases declining with age, especially in children, and picking up among the elderly. The study also finds a correlation between the burden of urticaria and the SDI, with the central part of the SDI showing a consistent increasing trend.

Conclusion

This study found that the global burden of urticaria has risen from 1990 to 2019. Factors like geographic location, gender, and SDI influenced the urticaria burden. Overall, these results offer a resource to guide public health strategies seeking to reduce the burden of urticaria.

Stress Affects Mast Cell Proteases in Murine Skin in a Model of Atopic Dermatitis-like Allergic Inflammation

Stress exposure worsens allergic inflammatory diseases substantially. Mast cells (MCs) play a key role in peripheral immune responses to neuroendocrine stress mediators such as nerve growth factor (NGF) and substance P (SP). Mast cell proteases (MCPs) and cholinergic factors (Chrna7, SLURP1) were recently described to modulate MC stress response. We studied MCPs and Chrna7/SLURP1 and their interplay in a mouse model for noise induced stress (NiS) and atopic dermatitis-like allergic inflammation (AlD) and in cultured MC lacking Chrna7. We found that the cholinergic stress axis interacts with neuroendocrine stress mediators and stress-mediator cleaving enzymes in AlD. SP-cleaving mMCP4+ MC were upregulated in AlD and further upregulated by stress in NiS+AlD. Anti-NGF neutralizing antibody treatment blocked the stress-induced upregulation in vivo, and mMCP4+ MCs correlated with measures of AlD disease activity. Finally, high mMCP4 production in response to SP depended on Chrna7/SLURP1 in cultured MCs. In conclusion, mMCP4 and its upstream regulation by Chrna7/SLURP1 are interesting novel targets for the treatment of allergic inflammation and its aggravation by stress.

Ganoderma lucidum extract attenuates corticotropin-releasing hormone-induced cellular senescence in human hair follicle cells

Corticotropin-releasing hormone (CRH) is a key mediator in stress-induced hair growth inhibition. Here, we investigated the impact of stress-induced senescence and evaluated the potential of Ganoderma lucidum (GL) extract in mitigating CRH-induced senescence in human hair follicle cells (hHFCs). We show that CRH treatment increased the senescence-associated beta-galactosidase (SA-β-GAL) activity and reactive oxygen species (ROS) formation in hHFCs and suppressed alkaline phosphatase (ALP) activity and anagen-inducing genes. However, GL extract restored ALP activity and decreased the expression levels of anagen-related genes in CRH-treated hHFCs. It decreased SA-β-GAL activity, reduced ROS production, and prevented the phosphorylation of MAPK signaling pathways in CRH-related stress response. Moreover, GL reversed the CRH-induced inhibition of two-cell assemblage (TCA) elongation and Ki67 expression. GL extract attenuates stress-induced hair follicular senescence by delaying catagen entry and scavenging ROS. Our findings suggest that GL extract could be used for treating stress-induced hair loss.

Inferring skin-brain-skin connections from infodemiology data using dynamic Bayesian networks

The relationship between skin diseases and mental illnesses has been extensively studied using cross-sectional epidemiological data. Typically, such data can only measure association (rather than causation) and include only a subset of the diseases we may be interested in. In this paper, we complement the evidence from such analyses by learning an overarching causal network model over twelve health conditions from the Google Search Trends Symptoms public data set. We learned the causal network model using a dynamic Bayesian network, which can represent both cyclic and acyclic causal relationships, is easy to interpret and accounts for the spatio-temporal trends in the data in a probabilistically rigorous way. The causal network confirms a large number of cyclic relationships between the selected health conditions and the interplay between skin and mental diseases. For acne, we observe a cyclic relationship with anxiety and attention deficit hyperactivity disorder (ADHD) and an indirect relationship with depression through sleep disorders. For dermatitis, we observe directed links to anxiety, depression and sleep disorders and a cyclic relationship with ADHD. We also observe a link between dermatitis and ADHD and a cyclic relationship between acne and ADHD. Furthermore, the network includes several direct connections between sleep disorders and other health conditions, highlighting the impact of the former on the overall health and well-being of the patient. The average R 2 for a condition given the values of all conditions in the previous week is 0.67: in particular, 0.42 for acne, 0.85 for asthma, 0.58 for ADHD, 0.87 for burn, 0.76 for erectile dysfunction, 0.88 for scars, 0.57 for alcohol disorders, 0.57 for anxiety, 0.53 for depression, 0.74 for dermatitis, 0.60 for sleep disorders and 0.66 for obesity. Mapping disease interplay, indirect relationships, and the key role of mediators, such as sleep disorders, will allow healthcare professionals to address disease management holistically and more effectively. Even if we consider all skin and mental diseases jointly, each disease subnetwork is unique, allowing for more targeted interventions.

Role of neurogenic inflammation in the pathogenesis of alopecia areata

Alopecia areata refers to an autoimmune illness indicated by persistent inflammation. The key requirement for alopecia areata occurrence is the disruption of immune-privileged regions within the hair follicles. Recent research has indicated that neuropeptides play a role in the damage to hair follicles by triggering neurogenic inflammation, stimulating mast cells ambient the follicles, and promoting apoptotic processes in keratinocytes. However, the exact pathogenesis of alopecia areata requires further investigation. Recently, there has been an increasing focus on understanding the mechanisms of immune diseases resulting from the interplay between the nervous and the immune system. Neurogenic inflammation due to neuroimmune disorders of the skin system may disrupt the inflammatory microenvironment of the hair follicle, which plays a crucial part in the progression of alopecia areata.

Mast Cells in Autism Spectrum Disorder-The Enigma to Be Solved?

Autism Spectrum Disorder (ASD) is a disturbance of neurodevelopment with a complicated pathogenesis and unidentified etiology. Many children with ASD have a history of "allergic symptoms", often in the absence of mast cell (MC)-positive tests. Activation of MCs by various stimuli may release molecules related to inflammation and neurotoxicity, contributing to the development of ASD. The aim of the present paper is to enrich the current knowledge on the relationship between MCs and ASD by discussing key molecules and immune pathways associated with MCs in the pathogenesis of autism. Cytokines, essential marker molecules for MC degranulation and therapeutic targets, are also highlighted. Understanding the relationship between ASD and the activation of MCs, as well as the involved molecules and interactions, are the main points contributing to solving the enigma. Key molecules, associated with MCs, may provide new insights to the discovery of drug targets for modeling inflammation in ASD.

Functional brain alterations in symptomatic dermographism patients-An exploratory magnetoencephalography study

Symptomatic dermographism (SD) is a common form of urticaria, which is triggered by stroking the skin. Brain involvement in its aetiology was investigated by means of magnetoencephalography (MEG) after provocation with histamine and dermography. Wheals were induced by histamine skin prick test and dermography in twelve SD patients and fourteen controls. Itch severity was scored on a Visual Analogue Scale (VAS). Relative power and functional connectivity (FC) were measured using a 306-channel whole-head MEG system at baseline and 10 min after histamine and dermography, and contrasted between groups and conditions. Furthermore, wheal diameter and itch scores after these procedures were correlated with the MEG values. SD patients had higher itch scores after histamine and dermography. No significant group-differences were observed in relative power or FC for any condition. In both groups, power decreases were mostly observed in the beta band, and power increases in the alpha bands, after provocation, with more regions involved in patients compared to controls. Increased FC was seen after histamine in patients, and after dermography in controls. In patients only, dermography and histamine wheal size correlated with the alpha2 power in the regions of interest that showed significant condition effects after these procedures. Our findings may be cautiously interpreted as aberrant itch processing, and suggest involvement of the central nervous system in the aetiology of SD.

Local and systemic mechanisms that control the hair follicle stem cell niche

Hair follicles are essential appendages of the mammalian skin, as hair performs vital functions of protection, thermoregulation and sensation. Hair follicles harbour exceptional regenerative abilities as they contain multiple somatic stem cell populations such as hair follicle stem cells (HFSCs) and melanocyte stem cells. Surrounding the stem cells and their progeny, diverse groups of cells and extracellular matrix proteins are organized to form a microenvironment (called 'niche') that serves to promote and maintain the optimal functioning of these stem cell populations. Recent studies have shed light on the intricate nature of the HFSC niche and its crucial role in regulating hair follicle regeneration. In this Review, we describe how the niche serves as a signalling hub, communicating, deciphering and integrating both local signals within the skin and systemic inputs from the body and environment to modulate HFSC activity. We delve into the recent advancements in identifying the cellular and molecular nature of the niche, providing a holistic perspective on its essential functions in hair follicle morphogenesis, regeneration and ageing.

Peripheral inflammation-induced changes in songbird brain gene expression: 3' mRNA transcriptomic approach

Species-specific neural inflammation can be induced by profound immune signalling from periphery to brain. Recent advances in transcriptomics offer cost-effective approaches to study this regulation. In a population of captive zebra finch (Taeniopygia guttata), we compare the differential gene expression patterns in lipopolysaccharide (LPS)-triggered peripheral inflammation revealed by RNA-seq and QuantSeq. The RNA-seq approach identified more differentially expressed genes but failed to detect any inflammatory markers. In contrast, QuantSeq results identified specific expression changes in the genes regulating inflammation. Next, we adopted QuantSeq to relate peripheral and brain transcriptomes. We identified subtle changes in the brain gene expression during the peripheral inflammation (e.g. up-regulation in AVD-like and ACOD1 expression) and detected co-structure between the peripheral and brain inflammation. Our results suggest benefits of the 3'end transcriptomics for association studies between peripheral and neural inflammation in genetically heterogeneous models and identify potential targets for the future brain research in birds.

The Effect of Liposomes of Various Compositions on the Skin and Its Derivatives After II-IIIA Degree Thermal Burns

This study examines the pathological processes and conditions arising from an experimental modeling of II-IIIA degree thermal burns in laboratory animals. These conditions are characterized by skin structure defects, diminished skin functions, especially the barrier function, and damage to skin derivatives like hair follicles and sebaceous glands. We compared the effect of liposomes composed of soybean lecithin of 90% phosphatidylcholine content and liposomes composed of lecithin of 26% phosphatidylcholine content on the epidermis, dermis and its capillaries, hair follicles, and the sebaceous glands of the laboratory animals 24 h after experimental modeling of II-IIIA degree thermal skin burns. We discuss the dependency of liposome effects on the skin and its derivatives on the fatty acid composition of the lecithin used, with particular focus on phosphatidylinositol, phosphatidic acids, as well as oleic and linoleic acids.

Skin Disease and Behavior Changes in the Cat

The health of the skin and coat of a cat is connected to the behavioral health of the animal. Stressed animals can cause lesions to their skin and coat such as alopecia, ulcers, and self-mutilation. On the other hand, localized or systemic health problems can cause stress, or pain, and therefore can increase overgrooming and poor skin health. When treating overgrooming and related skin lesions, all the physical and behavioral causes must be addressed through a multimodal approach.

Gateway reflexes describe novel neuro-immune communications that establish immune cell gateways at specific vessels

Neuroinflammation is an important biological process induced by complex interactions between immune cells and neuronal cells in the central nervous system (CNS). Recent research on the bidirectional communication between neuronal and immunological systems has provided evidence for how immune and inflammatory processes are regulated by nerve activation. One example is the gateway reflex, in which immune cells bypass the blood brain barrier and infiltrate the CNS to cause neuroinflammation. We have found several modes of the gateway reflex in mouse models, in which gateways for immune cells are established at specific blood vessels in the spinal cords and brain in experimental autoimmune encephalomyelitis and systemic lupus erythematosus models, at retinal blood vessels in an experimental autoimmune uveitis model, and the ankle joints in an inflammatory arthritis model. Several environmental stimulations, including physical and psychological stresses, activate neurological pathways that alter immunological responses via the gateway reflex, thus contributing to the development/suppression of autoimmune diseases. In the manuscript, we describe the discovery of the gateway reflex and recent insights on how they regulate disease development. We hypothesize that artificial manipulation of specific neural pathways can establish and/or close the gateways to control the development of autoimmune diseases.

Inflammation and Psoriasis: A Comprehensive Review

Psoriasis is an immune-mediated disease with a strong genetic component that brings many challenges to sick individuals, such as chronic illness, and which has multiple associated comorbidities like cardiovascular disease, metabolic syndrome, inflammatory bowel disease, and psychological disorders. Understanding the interplay between the innate and adaptative immune system has led to the discovery of specific cytokine circuits (Tumor Necrosis Factor-alpha (TNF-α), IL-23, IL-17), which has allowed scientists to discover new biomarkers that can be used as predictors of treatment response and pave the way for personalized treatments. In this review, we describe the footprint psoriasis leaves on the skin and beyond, key pathophysiological mechanisms, current available therapeutic options, and drawbacks faced by existing therapies, and we anticipate potential future perspectives that may improve the quality of life of affected individuals.

The Communication from Immune Cells to the Fibroblasts in Keloids: Implications for Immunotherapy

Keloids are a type of fibrotic disease characterized by excessive collagen production and extracellular matrix (ECM) deposition. The symptoms of pain and itching and frequent recurrence after treatment significantly impact the quality of life and mental health of patients. A deeper understanding of the pathogenesis of keloids is crucial for the development of an effective therapeutic approach. Fibroblasts play a central role in the pathogenesis of keloids by producing large amounts of collagen fibers. Recent evidence indicates that keloids exhibit high immune cell infiltration, and these cells secrete cytokines or growth factors to support keloid fibroblast proliferation. This article provides an update on the knowledge regarding the keloid microenvironment based on recent single-cell sequencing literature. Many inflammatory cells gathered in keloid lesions, such as macrophages, mast cells, and T lymphocytes, indicate that keloids may be an inflammatory skin disease. In this review, we focus on the communication from immune cells to the fibroblasts and the potential of immunotherapy for keloids. We hope that this review will trigger interest in investigating keloids as an inflammatory disease, which may open up new avenues for drug development by targeting immune mediators.

The role of dexamethasone in mediating the contradictory effects of Wnt antagonists SFRP2 and SFRP3 on human hair follicle growth

Stress can be one of the leading causes of hair loss. Stress related hormones, glucocorticoids (GCs), secretion by hair follicle have been mentioned in literature and proven to exert an inhibitory effect on hair follicle cells growth by modulating the expression of target genes related to cell proliferation and cycling. The gene modulating effect of the synthetic GC, dexamethasone (DEX), in human dermal papilla (DP) cells has been outlined in this study by mediating a contradictory effect on the expression of secreted frizzled related protein 2 (SFRP2) and SFRP3. The SFRP2 and SFRP3 possess a regulating effect on wnt signaling pathway. Their structural similarities to the cysteine-rich-domain of the frizzled receptors (FZD) allow their binding to the wnt ligands causing the blocking of the wnt ligands-receptors complex. The SFRP family members have been known as inhibitors of the wnt signaling modulating the proliferation and development of various cells. In hair follicle cells, SFRP2 activity has been reported positively on the proliferation of keratinocytes. However, the SFRP3 effect hasn't been well addressed. Under stress, the investigation of the mRNA and protein expressions of SFRP members in human DP cells revealed opposite expressions where SFRP2 decreased while SFRP3 increased by DEX. The proliferation rate of hair keratinocytes outer root sheath was detected via immunofluorescence highlighting the stimulatory effect of SFRP2 and the inhibitory effect of SFRP3. Here, we sought to determine the effect of GC agonist on SFRPs expression and their effect on hair follicle growth.

Polymorphisms in corticotrophin-releasing hormone-proopiomalanocortin (CRH-POMC) system genes: Neuroimmune contributions to psoriasis disease

BACKGROUND

Skin is a target organ and source of the corticotropin-releasing hormone-proopiomelanocortin (CRH-POMC) system, operating as a coordinator and executor of responses to stress. Environmental stress exacerbates and triggers inflammatory skin diseases through modifying the cellular components of the immune system supporting the importance of CRH-POMC system in the pathogenesis of psoriasis. The aim of this study was to analyse the association of CRH-POMC polymorphisms with psoriasis and evaluate transcript expression of lesional psoriatic and normal skin in RNA-seq data.

METHODS

Samples of 104 patients with psoriasis and 174 healthy controls were genotyped for 42 single nucleotide polymorphisms (SNPs) of CRH-POMC using Applied Biosystems SNPlex™ method. The transcript quantification was performed using Salmon software v1.3.0.

RESULTS

This study demonstrated the associations between melanocortin 1 receptor (MC1R) polymorphisms rs2228479, rs3212369, dopachrome tautomerase (DCT) polymorphisms rs7987802, rs2031526, rs9524501 and psoriasis in the Tatar population. Very strong association was evident for the SNP rs7987802 in the DCT gene (pc  = 5.95е-006) in psoriasis patients. Additionally, the haplotype analysis provided AT DCT (rs7992630 and rs7987802) and AGA MC1R (rs3212358, 2228479 and 885479) haplotypes significantly associated (pc  ˂ 0.05) with psoriasis in the Tatar population, supporting the involvement of DCT and MC1R to the psoriasis susceptibility. Moreover, MC1R-203 and DCT-201 expression levels were decreased in psoriasis lesional skin compared with healthy control skin.

CONCLUSIONS

This study is the first to identify genetic variants of the MC1R and DCT genes significantly associated with psoriasis in Tatar population. Our results support potential roles of CRH-POMC system genes and DCT in the pathogenesis of psoriasis.

Psychosocial factors and chronic spontaneous urticaria: a systematic review

BACKGROUND

Psychosocial factors have been informally associated with Chronic Spontaneous Urticaria (CSU); however, the relationship between psychosocial factors and CSU remains relatively unexplored in the scientific literature.

OBJECTIVE

This review aims to provide an evaluation of peer reviewed studies exploring psychosocial factors and CSU.

METHODS

A systematic search was performed over four databases identifying studies exploring psychosocial factors in relation to CSU published between the years 1995 and 2022.

RESULTS

Eighteen studies were included for narrative analysis, and 33 psychosocial factors were identified. These were split into two subgroups: psychosocial factors that were associated with CSU symptoms aggravation/onset (n = 20), and psychosocial factors expected to be impacted by CSU symptoms (n = 13).

CONCLUSION

This review has highlighted a need for more research and interventions to support individuals with psychosocial factors involved in CSU.

"Mens Sana in Cute Sana"-A State of the Art of Mutual Etiopathogenetic Influence and Relevant Pathophysiological Pathways between Skin and Mental Disorders: An Integrated Approach to Contemporary Psychopathological Scenarios

The negative socioeconomic impact of mental health disorders and skin diseases has increased in part due to the conflict between Russia and Ukraine, which has been a fertile ground for the emergence of psychopathologies. It is firmly established that there is a direct thread of etiopathogenetic communication between skin diseases and neuropsychiatric disorders, and the literature has tried to reveal the pathophysiological mechanisms governing such bidirectionality. This paper discusses this complex network of molecular pathways that are targeted by conventional and biological pharmacological agents that appear to impact two pathological spheres that previously seemed to have little connection. This molecular discussion is supplemented with a literature review, from a clinical viewpoint, regarding skin-brain etiopathogenetic bidirectionality. We focus on post-traumatic stress disorder (PTSD), which can be considered for all intents and purposes a systemic inflammatory disease that also affects the skin. A brief overview is also provided on the diagnostic-therapeutic and follow-up potential of oxidative and inflammatory markers potentially involved in the pathophysiological mechanisms treated. The aim is to clarify how these mechanisms may be useful in defining different stress-coping strategies and thus individual phenotypes of stress sensitivity/resistance in order to promote personalized medicine in the field of psychodermatology.

Atopic Dermatitis: Disease Features, Therapeutic Options, and a Multidisciplinary Approach

The latest findings regarding AD pathogenesis point to an impaired function of the epidermal barrier, changed immune response, colonization of the skin by microorganisms, and certain psychological factors among other causes/triggers. The inflammatory response of AD patients is mainly associated with the activation of T cells (Th2 cells predominate), dendritic cells, macrophages, keratinocytes, mast cells, and eosinophils. Therapy usually involves medical evaluations and adequate management including treatment of concomitant diseases (e.g., allergies and infections), patient education and nursing care, psychological support, and nutritional consultations, which are organized through specific programs and structured educational groups. Systemic AD therapy includes conventional systemic treatment (cyclosporine, methotrexate, azathioprine) and new, specific drugs, interleukin inhibitors (e.g., dupilumab) and JAK inhibitors (baricitinib, abrocitinib, upadacitinib, etc.). Since many AD patients are affected by various psychological factors and comorbidities, they should be assessed and managed through a multidisciplinary approach, involving different professions (psychologists, ear-nose-throat specialists, pulmonologists, allergologists, immunologists, nutritionists, pediatricians, gastroenterologists, psychiatrists (when necessary), and others). A multidisciplinary approach provides better coping strategies and improves control over the disease, patient adherence to therapy, and quality of life. It also has a positive influence on family quality of life while at the same time making more efficient use of dermatology healthcare resources, reducing the economic burden on both patients and society.

A catena between psychiatric disorders and non-scarring alopecias-A systematic review

For many years, clinical observations have suggested that there is an intrinsic connection between psychological state and skin diseases. Stress responses are typically mediated by several hormones, which are modulated via the hypothalamic-pituitary-adrenal axis. This typical stress response is not only one theory for psychiatry disorder pathophysiology, but it also modifies hair growth by altering the skin's inflammatory environment. Given that different forms of hair loss, such as androgenetic alopecia, alopecia areata, or telogen effluvium, and hair follicle cycling can be altered by immune cells within the follicle milieu, we hypothesized that specific forms of hair loss are correlated to psychiatric illnesses. To address this, we conducted a systematic review by searches in April and May 2021 through Ovid MEDLINE and PUBMED (ranging from 1951 to the present day), identifying 179 reports. A further 24 reports were identified through website and citation searches giving a total of 201 reports. After applying exclusion criteria, 21 papers were reviewed, and 17 were included for data analysis. It is undeniable that hair loss greatly affects Health-related Quality of Life (HrQol) and it is heavily associated with major depressive disorder and anxiety. The correlation between hair loss and mental health disorders was significant, however, due to the low number of publications with quantitative data we were not able to identify correlations between each hair loss type with each psychiatric disorder. Further studies to better connect specific hair loss diseases to specific disorders are therefore critical in bettering the way both psychiatric disease, and hair loss, are managed.

Evidence for a causal association between psoriasis and psychiatric disorders using a bidirectional Mendelian randomization analysis in up to 902,341 individuals

BACKGROUND

The causal association between psoriasis and psychiatric disorders remains ambiguous.

OBJECTIVES

This study aimed to investigate the causal relationship between psoriasis and common psychiatric disorders using bidirectional Mendelian randomization (MR) analysis.

METHODS

Major depressive disorder (MDD) (N = 217,584), bipolar disorder (N = 51,710), schizophrenia (N = 77,096), and anxiety disorder (N = 218,792) were obtained as outcomes, and psoriasis (N = 337,159) were as exposure. Inverse variance weighting (IVW) was used as the main method, with other sensitivity methods as auxiliary methods. Sensitivity analysis and heterogeneity tests were performed to ensure the robustness of the results. We also performed a subgroup analysis of cases with psoriatic arthritis (PsA) (N = 213,879) by using the same testing methods.

RESULTS

MR showed that the genetic risk of psoriasis was positively associated with bipolar disorder (odds ratio (OR) = 13.54, 95 % confidence interval (95%CI): 2.43-75.37, P = 0.002) and MDD (OR = 1.08, 95%CI: 1.01-1.15, P = 0.027), which indicated possible causal relationships between psoriasis and these two diseases. Schizophrenia (OR = 3.52, 95%CI: 0.22-55.71, P = 0.372) and anxiety disorders (OR = 0.65, 95%CI: 0.16-2.63, P = 0.546) indicated no significant causal association. No reverse causal effects of psychiatric disorders on psoriasis were found. Subgroup analysis also suggested causal association of PsA with the bipolar affective disorder (OR = 1.05, 95%CI: 1.01-1.08, P = 0.005).

LIMITATIONS

Potential pleiotropic effects, restriction to European populations, and differences in diagnostic criteria.

CONCLUSIONS

This study has supported the causal association of psoriasis with MDD and bipolar disorder, and the subtype PsA with bipolar disorder, which informed the intervention for mental illnesses in patients with psoriasis.

Potential effects of shift work on skin autoimmune diseases

Shift work is associated with systemic chronic inflammation, impaired host and tumor defense and dysregulated immune responses to harmless antigens such as allergens or auto-antigens. Thus, shift workers are at higher risk to develop a systemic autoimmune disease and circadian disruption with sleep impairment seem to be the key underlying mechanisms. Presumably, disturbances of the sleep-wake cycle also drive skin-specific autoimmune diseases, but epidemiological and experimental evidence so far is scarce. This review summarizes the effects of shift work, circadian misalignment, poor sleep, and the effect of potential hormonal mediators such as stress mediators or melatonin on skin barrier functions and on innate and adaptive skin immunity. Human studies as well as animal models were considered. We will also address advantages and potential pitfalls in animal models of shift work, and possible confounders that could drive skin autoimmune diseases in shift workers such as adverse lifestyle habits and psychosocial influences. Finally, we will outline feasible countermeasures that may reduce the risk of systemic and skin autoimmunity in shift workers, as well as treatment options and highlight outstanding questions that should be addressed in future studies.

Stress Concepts and Applications in Various Matrices with a Focus on Hair Cortisol and Analytical Methods

When studying stress in animals, it is important to understand the types of stress and their classification, and how to assess the stress levels in different animal species using different matrices accurately and precisely. The classification of stress types helps to distinguish between good stress (eustress) and bad stress (distress). Hence, first, it is crucial to assess the animal's level of stress in a non-intrusive manner and second to identify the type of stress that is best suited to its environment. Third, it is also important to analyze the obtained samples using a suitable method to increase the validity of stress hormone measurements. Therefore, in this review, we aim to: (1) explain the classification of stress, (2) discuss the wide range of body matrices (e.g., saliva, milk, hair, urine, feces, sweat, fins, etc.) that can be used as samples to evaluate stress levels, as well as their comparisons and limitations, and present the reliable matrices for measuring stress hormones with special emphasis on hair, (3) compare the analytical methods for measuring stress hormones after sample preparation. Despite some literature that does not include hair as a reliable matrix for evaluating stress levels, hair is one of the matrices for measuring long-term stress hormone accumulations. This review discusses some factors that influence the level of stress hormones in the hair. By understanding these issues, the scientific community will not only be able to improve the understanding of stress and biomarker evaluation but also suggest how to deal with the consequences of stress in future research.

The impact of perceived stress on the hair follicle: Towards solving a psychoneuroendocrine and neuroimmunological puzzle

While popular belief harbors little doubt that perceived stress can cause hair loss and premature graying, the scientific evidence for this is arguably much thinner. Here, we investigate whether these phenomena are real, and show that the cyclic growth and pigmentation of the hair follicle (HF) provides a tractable model system for dissecting how perceived stress modulates aspects of human physiology. Local production of stress-associated neurohormones and neurotrophins coalesces with neurotransmitters and neuropeptides released from HF-associated sensory and autonomic nerve endings, forming a complex local stress-response system that regulates perifollicular neurogenic inflammation, interacts with the HF microbiome and controls mitochondrial function. This local system integrates into the central stress response systems, allowing the study of systemic stress responses affecting organ function by quantifying stress mediator content of hair. Focusing on selected mediators in this "brain-HF axis" under stress conditions, we distill general principles of HF dysfunction induced by perceived stress.

The redox modulatory effects of SP/NK1R system: Implications for oxidative stress-associated disorders

Oxidative stress which refers to redox imbalance with increased generation of reactive oxygen species (ROS) has been associated with the pathophysiology of diverse disease conditions. Recently, a close, yet not fully understood, relation between oxidative stress and neuropeptides, in particular, substance P (SP), has been reported in certain conditions. SP has been shown to affect the cellular redox environment through activation of neurokinin-1receptor (NK1R). It seems that SP/NK1R system and oxidative stress can act either synergistically or antagonistically in a context-dependent manner, thereby, influencing the pathology of various clinical disorders either destructively or protectively. Importantly, the interactions between oxidative stress and SP/NK1R system can be pharmacologically targeted. Therefore, a better understanding of the redox modulatory properties of SP/NK1R signaling will pave the way for identifying new therapeutic possibilities for attenuating oxidative stress-mediated damage. Towards this end, we performed a comprehensive search through PubMed/Medline and Scopus databases and discussed all related existing literature regarding the interplay between oxidative stress and SP/NK1R system as well as their implication in various clinical disorders, to provide a clear view and hence better management of oxidative damage.

Effects of oxidative stress induced by environmental relevant concentrations of fluoxetine on the embryonic development on Danio rerio

Fluoxetine (FLX) is a psychoactive drug that acts as an antidepressant. FLX is one of the world's best-selling prescription antidepressants. FLX is widely used for the treatment of various psychiatric disorders. For these reasons, this drug may eventually end up in the aquatic environment via municipal, industrial, and hospital discharges. Even though the occurrence of FLX in aquatic environments has been reported as ubiquitous, the toxic effects that this drug may induce, especially at environmentally relevant concentrations, on essential biological processes of aquatic organisms require more attention. In the light of this information, this work aimed to investigate the influence that fluoxetine oxidative stress-induced got over the embryonic development of Danio rerio. For this purpose, D. rerio embryos (4 h post fertilization) were exposed to environmentally relevant concentrations (5, 10, 15, 20, 25, 30, 35, and 40 ng L^-1) of fluoxetine, until 96 h post fecundation. Along the exposure, survival, alterations to embryonic development, and teratogenic effects were evaluated using a stereomicroscope. Furthermore, oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation, hydroperoxide, and carbonyl content) were evaluated at 72 and 96 h post fecundation. LC₅₀, EC_50m, and teratogenic index were 30 ng L^-1, 16 ng L^-1, and 1.9, respectively. The main teratogenic effects induced by fluoxetine were pericardial edema, hatching retardation, spine alterations and craniofacial malformations. Concerning oxidative stress, our integrated biomarkers (IBR) analysis demonstrated that as the concentration increased, oxidative damage biomarkers got more influence over the embryos than antioxidant enzymes. Thus, fluoxetine induces an important oxidative stress response on the embryos of D. rerio. Collectively, our results allow us to concluded that FLX is a dangerous drug in the early life stages of D. rerio due to its high teratogenic potential and that FLX-oxidative stress induced may be involved in this toxic process.

The Correlation between Serum Cortisol Levels with Stretch Marks in Gymnastic Male

BACKGROUND: Stretch marks are skin scar tissue that appears in the form of purplish linear atrophy, erythematous or hypopigmented which is often caused by excessive stretching of the skin. Increased cortisol levels can cause an increase in collagen degradation which results in disruption of the extracellular matrix in the dermis, resulting in stretch marks. Physical stress can trigger activation of the hypothalamic-pituitary-adrenal axis, which will induce activation of stress hormones, including cortisol in the adrenal cortex. AIM: The objective of the study is to determine the correlation between serum cortisol levels and stretch marks in male at a gymnastics training site. SUBJECTS AND METHODS: Observational analytic study with a cross-sectional approach to 50 stretch marks subjects. RESULTS: Serum cortisol levels of subjects with stretch marks averaged 9.72 g/dL with the lowest level of 4.45 g/dL and the highest level of 49.25 g/dL (p < 0.001). The highest age with stretch marks was 26–30 years 18 (36%) subjects and the lowest age was aged 36–40 years 5 (10%) subjects. The majority of stretch marks are located in the axillary region (30.9%), brachii (23.6%), and abdomen (18.4%). The average cortisol level in subjects with aerobic exercise was 6.52 g/dL, muscle training 11.18 g/dL, mixed aerobic and muscle training 7.5 g/dL. The highest average cortisol levels were at exercise duration of 31–60 min of 12.88 g/dL, 61–90 min of 6.63 g/dL, and 91–120 min of 6.2 g/dL. The highest frequency of exercise in a week was 3–4 times as many as 30 subjects (60%) with an average serum cortisol level of 11.1879 g/dL. CONCLUSION: There is a significant correlation between serum cortisol levels and stretch marks in male at gymnastics training.

The Brain-Skin Axis in Psoriasis-Psychological, Psychiatric, Hormonal, and Dermatological Aspects

Psoriasis is a chronic inflammatory skin disease with systemic manifestation, in which psychological factors play an important role. The etiology of psoriasis is complex and multifactorial, including genetic background and environmental factors such as emotional or physical stress. Psychological stress may also play a role in exacerbation of psoriasis, by dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, sympathetic–adrenal–medullary axis, peripheral nervous system, and immune system. Skin cells also express various neuropeptides and hormones in response to stress, including the fully functional analog of the HPA axis. The deterioration of psoriatic lesions is accompanied by increased production of inflammatory mediators, which could contribute to the imbalance of neurotransmitters and the development of symptoms of depression and anxiety. Therefore, deregulation of the crosstalk between endocrine, paracrine, and autocrine stress signaling pathways contributes to clinical manifestations of psoriasis, which requires multidisciplinary approaches.

Atopic Dermatitis Severity, Patient Perception of the Disease, and Personality Characteristics: How Are They Related to Quality of Life?

INTRODUCTION

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin condition that greatly affects patients' quality of life, psychological condition, and social relationships.

MATERIALS AND METHODS

To analyze different aspects of AD patients' quality of life, we used the SCORing Atopic Dermatitis (SCORAD) index (for AD severity), the Dermatology Life Quality Index (DLQI), the World Health Organization Quality of Life Brief Version (WHOQOL-BREF), the Brief Illness Perception Questionnaire (Brief IPQ), and the Crown-Crisp Experiential Index (CCEI) to analyze personality traits. The study included 84 AD patients, 42 with clinical manifestations and 42 in remission.

RESULTS

SCORAD values correlated positively and linearly with DLQI (r = 0.551; p < 0.001) and with disease impact on life, disease control, and disease symptoms (r = 0.350-0.398; p ≤ 0.023). DLQI was also related to certain personality characteristics (free-floating anxiety disorder, obsession, somatization, and depression (p ≤ 0.032)). Symptomatic AD patients had a significantly more impaired DLQI than asymptomatic patients (p < 0.001) and the two groups differed in some IPQ dimensions, but they did not differ significantly concerning the WHOQOL-BREF dimensions and personality traits (CCEI).

CONCLUSION

Since AD patient quality of life was dependent not only on disease severity but was also influenced by patient personality characteristics (anxiety disorder, obsession, somatization, depression), many factors need to be taken into account to create effective, patient-specific therapy regimens.

The hair follicle-psoriasis axis: Shared regulatory mechanisms and therapeutic targets

It has long been known that there is a special affinity of psoriasis for the scalp: Here, it occurs most frequently, lesions terminate sharply in frontal skin beyond the hair line and are difficult to treat. Yet, surprisingly, scalp psoriasis only rarely causes alopecia, even though the pilosebaceous unit clearly is affected. Here, we systematically explore the peculiar, insufficiently investigated connection between psoriasis and growing (anagen) terminal scalp hair follicles (HFs), with emphasis on shared regulatory mechanism and therapeutic targets. Interestingly, several drugs and stressors that can trigger/aggravate psoriasis can inhibit hair growth (e.g. beta-blockers, chloroquine, carbamazepine, interferon-alpha, perceived stress). Instead, several anti-psoriatic agents can stimulate hair growth (e.g. cyclosporine, glucocorticoids, dithranol, UV irradiation), while skin/HF trauma (Köbner phenomenon/depilation) favours the development of psoriatic lesions and induces anagen in "quiescent" (telogen) HFs. On this basis, we propose two interconnected working models: (a) the existence of a bidirectional "hair follicle-psoriasis axis," along which keratinocytes of anagen scalp HFs secrete signals that favour the development and maintenance of psoriatic scalp lesions and respond to signals from these lesions, and (b) that anagen induction and psoriatic lesions share molecular "switch-on" mechanisms, which invite pharmacological targeting, once identified. Therefore, we advocate a novel, cross-fertilizing and integrative approach to psoriasis and hair research that systematically characterizes the "HF-psoriasis axis," focused on identification and therapeutic targeting of selected, shared signalling pathways in the future management of both, psoriasis and hair growth disorders.

Emerging insights into the immunological aspects of keloids

A special kind of scar, keloid, sometimes grows huge, disturbing patients in different ways. We discussed the pathogenesis of keloids and found researches about fibroblasts and collagen disorders, with little emphasis on immunity. Coupled with few effective treatments in keloid at present, we have focused on the immunological mechanisms of keloids with an aim to unravel some new therapeutic approaches in the future. In this review, the immunological processes are separately illustrated by the classification of different immune cells. In addition, we also discuss possible reasons for the repeated recurrence of keloids, the phenomenon of cell talks, and inflammation-related signal pathways involved in the pathogenesis of keloids.

Pruritus, Allergy and Autoimmunity: Paving the Way for an Integrated Understanding of Psychodermatological Diseases?

Pruritus is a key symptom in allergology and dermatology, contributing to the global and huge impact on quality of life related to skin disorders, both those which are not related to a primary dermatosis (illness) and those which are linked with primary skin lesions (disease). This is particularly evident within psychophysiological dermatoses, a group of psychodermatological diseases where there is a primary dermatosis, where psychological stress plays a role, and where pruritus may represent a major and shared symptom. The etiopathogenesis of pruritus in those disorders sheds light on the link among psychopathological features, psychological stress and the subtle interface between allergic and autoimmune mechanisms, where mast cells play a pivotal role. Allergy has long been recognised as an altered reactivity to exogenous antigens (allergens), defined as an immediate hypersensitivity mediated by immunoglobulin E (IgE). In turn, the immunological understanding of atopy is related to an immediate hypersensitivity reaction to environmental antigens involving T-helper 2 (Th2) responses and the IgE production. Mast cells are major cells in the early phase of allergy, releasing the mediators involved in the symptoms associated with the allergic disease, including pruritus, when the allergen cross-links with IgE, whose mechanisms can be observed in acute urticaria and atopy. Some allergic reactions may persist and allergy may eventually lead to autoimmunity, with the development of a T-helper 1 (Th1) and then IgE-independent inflammation. For instance, in chronic spontaneous urticaria, the mast cell activation may include autoimmune mechanisms, where autoantibodies against the extracellular α subunit of the high-affinity IgE receptor (FcεRIα) and to IgE are observed, with the involvement of Th1 lymphocytes and the production of interferon-γ (INF-γ). The role of autoimmunity is also suggested in the etiopathogenesis of other psychophysiological dermatoses, namely psoriasis, atopic dermatitis and alopecia areata. In the latter, for example, mast cells were reported to be linked with the loss of immune privilege and they are the key cells involved in the experience of pruritus, whose intensity was reported to precede and be correlated with the onset of the hair loss. Furthermore, considering that the role of hair and skin is wide, from psychosocial aspects (communication and social interaction) to vital functions (such as, temperature control), it is straightforward that they are central in our interactions and synchronization with others and the world; thereby, we may admit that the psychophysiological dermatoses could represent a loss of such synchronization. Furthermore, they are often linked with psychopathology which strongly connects with the concept of desynchronization, namely, sleep disorders and depressive symptoms, the clinical expression of a dysfunction in the interplay among mast cells, pineal gland and melatonin, thus the circadian rhythm, as well as their connection with the hypothalamic corticotrophin-releasing hormone (CRH), well-known for its key role in stress response. Moreover, increasing evidence has supported the existence of cutaneous equivalents for these mechanisms, connecting with those central pathways. Thereby, taking all these concepts into consideration, this review intends to look into the updated evidence on the shared biological mechanisms between allergy and autoimmunity, underlining pruritus as a core element, then revisiting the key role of mast cells and discussing the connection with melatonin and immune-inflammatory pathways in the physiopathology of psychophysiological dermatoses, thus paving the way for the understanding of their psychosomatic correlates and a comprehensive psychodermatological approach.

Optimization of Influential Variables in the Development of Buprenorphine and Bupivacaine Loaded Invasome for Dermal Delivery

Purpose: Hydrophilic drugs are extensively applied in clinical applications. Inadequate dermal penetration of these drugs is a great challenge. Incorporation of drugs into nano-carrier systems overcomes lower penetration drawbacks. Invasomes are novel nano-carrier systems which enhance transdermal penetration by using terpene and ethanol in their structures. buprenorphine and bupivacaine hydrochlorides are two potent analgesic drugs that are loaded simultaneously in the nano-invasome structure as opioid and non-opioid drugs.

Methods: The full factorial experimental design was used for planning and estimating optimum formulations of invasome systems. Three influential factors like terpene type, terpene concentration and preparation method were comprehensively analyzed for achieving high encapsulation efficiency (EE) and optimum size.

Results: The mean sizes of designed invasomes were in the range of 0.39-5.86 µm and high values of EE and loading capacity (LC) were reported as 98.77 and 19.75 for buprenorphine-loaded invasome, respectively. Zeta potential measurements confirmed that the obtained high value of EE might be as a result of reversible ionic interactions between positively charged drugs and negatively charged phospholipidic part of invasome structure. Another characterization of the prepared formulations was carried out by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and dynamic light scattering (DLS) technique.

Conclusion: The satisfactory obtained results of formulations encourage researchers to get optimum topical analgesic formulations with potent and rapid onset time properties required in invasive cutaneous procedures.

Recent Progress in the Understanding of the Effect of Sympathetic Nerves on Hair Follicle Growth

Clinical observation and experimental studies have long suggested that the perifollicular nerves have nutritional and regulatory effects on the growth, development, and physiological cycle of hair follicles (HFs), even though the concrete mechanism remains obscure. Recently, with the progress of immunohistochemistry and molecular biology techniques, more innovation has been made in the study of the follicular sympathetic nerves and its nerve-effect factor norepinephrine affecting hair follicle stem cells. This review highlights the progress in the regulation of the sympathetic nervous system toward the growth of HFs.

Modulation of dermal equivalent of hypothalamus-pituitary-adrenal axis in mastocytosis

Introduction

Mastocytosis is a rare disease characterized by abnormal growth and accumulation of tissue mast cells (MC) in one or more organ systems and is classified as being either cutaneous mastocytosis (CM) or systemic mastocytosis (SM). In the pioneer studies of Slominski's group, a fully functional hypothalamic-pituitary-adrenal axis equivalent has been discovered in various tissues, including skin.

Aim

In the present study we investigated potential involvement of hypothalamus-pituitary-adrenal (HPA) cutaneous equivalent in ongoing mastocytosis.

Material and methods

The expression of HPA elements: CRH, UCN1, UCN2, UCN3, CRHR1, POMC, MC1R, MC2R and NR3C1 was assessed for their mRNA level in skin biopsies of adult patients with mastocytosis and healthy donors (n = 16 and 19, respectively), while CRH, UCN1, CRHR1, ACTH and MC1R were selected for immunostaining assay (n = 13 and 7, respectively). The expression of CRH receptor 1 (CRHR1) isomers was investigated by RT-PCR. The ELISA was used for detection of cortisol, CRH, UCN and ACTH in the serum.

Results

The decrease in the expression of HPA element of skin equivalent was observed on both mRNA and protein levels, however quantification of immunohistochemical data was impeded due to melanin in epidermis. Furthermore, we observed infiltration of dermis with HPA elements overexpressing mononuclear cells, which is in the agreement with an in vitro study showing a high expression of HPA elements by mast cells.

Conclusions

Taken together, it was confirmed that the expression elements of HPA was modulated in mastocytosis, thus the potential involvement of general and local stress responses in its pathogenesis should be postulated and further investigated.

How stress affects the skin: from designs to mechanisms

Linked Article: Schmidt et al. Br J Dermatol 2021; 185:130–138.

Adult skin acute stress responses to short-term environmental and internal aggression from exposome factors

Exposome factors that lead to stressed skin can be defined as any disturbance to homeostasis from environmental (meteorological factors, solar radiation, pollution or tobacco smoke) and/or internal exposure (unhealthy diet, hormonal variations, lack of sleep, psychosocial stress). The clinical and biological impact of chronic exposome effects on skin functions has been extensively reviewed, whereas there is a paucity of information on the impact of short‐term acute exposure. Acute stress, which would typically last minutes to hours (and generally no more than a week), provokes a transient but robust neuroendocrine‐immune and tissue remodelling response in the skin and can alter the skin barrier. Firstly, we provide an overview of the biological effects of various acute stressors on six key skin functions, namely the skin physical barrier, pigmentation, defences (antioxidant, immune cell‐mediated, microbial and microbiome maintenance), structure (extracellular matrix and appendages), neuroendocrine and thermoregulation functions. Secondly, we describe the biological and clinical effects on adult skin from individual exposome factors that elicit an acute stress response and their consequences in skin health maintenance. Clinical manifestations of acutely stressed skin may include dry skin that might accentuate fine lines, oily skin, sensitive skin, pruritus, erythema, pale skin, sweating, oedema and flares of inflammatory skin conditions such as acne, rosacea, atopic dermatitis, pigmentation disorders and skin superinfection such as viral reactivation. Acute stresses can also induce scalp sensitivity, telogen effluvium and worsen alopecia.

The Role of the Environment and Exposome in Atopic Dermatitis

PURPOSE OF REVIEW

Atopic dermatitis (AD) is a chronic inflammatory skin disorder affecting up to 20% of children and up to 5% of adults worldwide, contributing to significant disease-related morbidity in this patient cohort. Its aetiopathogenesis is underpinned by multiple factors, including genetic susceptibility, skin barrier defects, a skewed cutaneous immune response and microbiome perturbation in both the skin and the gut. In this review, we aim to examine the biological effects of key environmental exposures (the sum of which is termed the "exposome") at the population, community and individual levels in order to describe their effect on AD pathogenesis.

RECENT FINDINGS

It is now understood that as well as considering the type of environmental exposure with regard to its effect on AD pathogenesis, the dosage and timing of the exposure are both critical domains that may lead to either exacerbation or amelioration of disease. In this review, we consider the effects of population-wide exposures such as climate change, migration and urbanization; community-specific exposures such as air pollution, water hardness and allergic sensitisation; and individual factors such as diet, microbiome alteration, psychosocial stress and the impact of topical and systemic therapy.

SUMMARY

This review summarises the interaction of the above environmental factors with the other domains of AD pathogenesis, namely, the inherent genetic defects, the skin barrier, the immune system and the cutaneous and gut microbiota. We specifically emphasise the timing and dosage of exposures and its effect on the cellular and molecular pathways implicated in AD.

Gyogamdan, a Traditional Medicine Prescription, Ameliorated Dermal Inflammation and Hyperactive Behavior in an Atopic Dermatitis Mouse Model Exposed to Psychological Stress

Psychological stress (PS) plays a significant role as an aggravating factor in atopic dermatitis (AD). The traditional medicine prescription, Gyogamdan, has been used to treat chest discomfort and mood disorders caused by PS. This study investigated the effects of an ethanolic extract of Gyogamdan (GGDE) on stress-associated AD models and the underlying mechanisms. 2,4-Dinitrochlorobenzene- (DNCB-) treated BALB/c mice were exposed to social isolation (SI) stress. The effects of orally administered GGDE (100 or 500 mg/kg) were evaluated by ELISA, western blotting, and an open field test (OFT). SI stress exaggerated the skin inflammation and induced locomotor hyperactivity in the AD mouse model. GGDE reduced the levels of IgE, TNF-α, IL-13, eotaxin, and VEGF and mast cell/eosinophil infiltration and prevented the decreases in the levels of involucrin and loricrin in the skin. GGDE also suppressed the SI-induced increases in corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and corticosterone (CORT) in socially isolated AD mice. Furthermore, GGDE reduced traveling distances and mean speed significantly in the OFT. The in vitro experiments were performed using HaCaT, HMC-1, PC12, and BV2 cells. In the TNF-α/IFN-γ- (TI-) stimulated HaCaT cells, GGDE decreased the thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) production significantly by inhibiting p-STAT1 and NF-κB signaling. GGDE also reduced VEGF production in HMC-1 cells stimulated with CRH/substance P (SP) by inhibiting p-ERK signaling pathway. GGDE increased the cell viability significantly and suppressed apoptosis in CORT-stimulated PC12 cells. Moreover, GGDE suppressed the LPS-induced production of NO, TNF-α, IL-1β, and IL-6 in BV2 cells. These results suggest that GGDE might be useful in patients with AD, which is exacerbated by PS.

New Pathways for the Skin's Stress Response: The Cholinergic Neuropeptide SLURP-1 Can Activate Mast Cells and Alter Cytokine Production in Mice

Background: The alpha7 nicotinic acetylcholine receptor (Chrna7) plays an essential anti-inflammatory role in immune homeostasis and was recently found on mast cells (MC). Psychosocial stress can trigger MC hyperactivation and increases pro-inflammatory cytokines in target tissues such as the skin. If the cholinergic system (CS) and Chrna7 ligands play a role in these cascades is largely unknown.

Objective: To elucidate the role of the CS in the response to psychosocial stress using a mouse-model for stress-triggered cutaneous inflammatory circuits.

Methods: Key CS markers (ACh, Ch, SLURP-1, SLURP-2, Lynx1, Chrm3, Chrna7, Chrna9, ChAT, VAChT, Oct3, AChE, and BChE) in skin and its MC (sMC), MC activation, immune parameters (TNFα, IL1β, IL10, TGFβ, HIF1α, and STAT3) and oxidative stress were analyzed in skin from 24 h noise-stressed mice and in cultured MC (cMC) from C57BL/6 or Chrna7-Knockout mice.

Results: First, Chrna7 and SLURP-1 mRNA were exclusively upregulated in stressed skin. Second, histomorphometry located Chrna7 and SLURP-1 in nerves and sMC and demonstrated upregulated contacts and increased Chrna7+ sMC in stressed skin, while 5 ng/mL SLURP-1 degranulated cMC. Third, IL1β+ sMC were high in stressed skin, and while SLURP-1 alone had no significant effect on cMC cytokines, it upregulated IL1β in cMC from Chrna7-KO and in IL1β-treated wildtype cMC. In addition, HIF1α+ sMC were high in stressed skin and Chrna7-agonist AR-R 17779 induced ROS in cMC while SLURP-1 upregulated TNFα and IL1β in cMC when HIF1α was blocked.

Conclusions: These data infer that the CS plays a role in the regulation of stress-sensitive inflammatory responses but may have a surprising pro-inflammatory effect in healthy skin, driving IL1β expression if SLURP-1 is involved.

Correlation Between Stress Scale and Serum Substance P Level in Acne Vulgaris

INTRODUCTION

Acne vulgaris is a chronic inflammatory disease of pilosebaceous follicles with polymorphic lesions, consisting of comedones, papules, pustules and nodules with varying degrees of severity. Stress is one of the triggers of acne vulgaris. Peripheral nerves release substance P in response to stress. Substance P causes proliferation and differentiation of sebaceous glands and increases lipid synthesis in sebocytes.

PURPOSE

To determine the correlation between stress scale and serum substance P level in acne vulgaris.

PATIENTS AND METHODS

This study was an observational analytic study with a cross-sectional design involving 30 patients with acne vulgaris and 30 controls. History taking, dermatological examination and the Holmes-Rahe stress scale questionnaire were performed with each patient to evaluate stress scale, followed by taking blood samples to assess substance P serum levels using the ELISA test. The collected data were analyzed using the Spearman correlation test.

RESULTS

In both groups, the majority of subjects were 23-27 years old (36.7%) and most of them were female (76.7%). The majority in the acne vulgaris group had low scores on the stress scale, represented by 17 patients (56.7%). The main cause of stress in the acne vulgaris group was a major change in sleeping habits (66.7%). In the acne vulgaris group, the highest mean value of serum substance P level in high stress scale group was 168.2 pg/mL. There was a positive correlation between stress scale and serum substance P level in acne vulgaris with moderate strength and this was statistically significant (r = 0.446; p = 0.014). Meanwhile, stress scale and serum substance P level in controls were not correlated and this was not statistically significant (r = -0.090; p = 0.636).

CONCLUSION

There was a correlation between stress scale and serum substance P level in acne vulgaris.

New effects of caffeine on corticotropin-releasing hormone (CRH)-induced stress along the intrafollicular classical hypothalamic-pituitary-adrenal (HPA) axis (CRH-R1/2, IP3 -R, ACTH, MC-R2) and the neurogenic non-HPA axis (substance P, p75NTR and TrkA) in ex vivo human male androgenetic scalp hair follicles

BACKGROUND

Human hair is highly responsive to stress, and human scalp hair follicles (HFs) contain a peripheral neuroendocrine equivalent of the systemic hypothalamic-pituitary-adrenal (HPA) stress axis. Androgenetic alopecia (AGA) is supposed to be aggravated by stress. We used corticotropin-releasing hormone (CRH), which triggers the HPA axis, to induce a stress response in human ex vivo male AGA HFs. Caffeine is known to reverse testosterone-mediated hair growth inhibition in the same hair organ culture model.

OBJECTIVES

To investigate whether caffeine would antagonize CRH-mediated stress in these HFs.

METHODS

HFs from balding vertex area scalp biopsies of men affected by AGA were incubated with CRH (10-7 mol L-1 ) with or without caffeine (0·001% or 0·005%).

RESULTS

Compared to controls, CRH significantly enhanced the expression of catagen-inducing transforming growth factor-β2 (TGF-β2) (P < 0·001), CRH receptors 1 and 2 (CRH-R1/2) (P < 0·01), adrenocorticotropic hormone (ACTH) (P < 0·001) and melanocortin receptor 2 (MC-R2) (P < 0·001), and additional stress-associated parameters, substance P and p75 neurotrophin receptor (p75NTR ). CRH inhibited matrix keratinocyte proliferation and expression of anagen-promoting insulin-like growth factor-1 (IGF-1) and the pro-proliferative nerve growth factor receptor NGF-tyrosine kinase receptor A (TrkA). Caffeine significantly counteracted all described stress effects and additionally enhanced inositol trisphosphate receptor (IP3 -R), for the first time detected in human HFs.

CONCLUSIONS

These findings provide the first evidence in ex vivo human AGA HFs that the stress mediator CRH induces not only a complex intrafollicular HPA response, but also a non-HPA-related stress response. Moreover, we show that these effects can be effectively antagonized by caffeine. Thus, these data strongly support the hypothesis that stress can impair human hair physiology and induce hair loss, and that caffeine may effectively counteract stress-induced hair damage and possibly prevent stress-induced hair loss.

Protecting the outside: biological tools to manipulate the skin microbiota

Interest surrounding the role that skin microbes play in various aspects of human health has recently experienced a timely surge, particularly among researchers, clinicians and consumer-focused industries. The world is now approaching a post-antibiotic era where conventional antibacterial therapeutics have shown a loss in effectiveness due to overuse, leading to the looming antibiotic resistance crisis. The increasing threat posed by antibiotic resistance is compounded by an inadequate discovery rate of new antibiotics and has, in turn, resulted in global interest for alternative solutions. Recent studies have demonstrated that imbalances in skin microbiota are associated with assorted skin diseases and infections. Specifically, restoration of this ecosystem imbalance results in an alleviation of symptoms, achieved simply by applying bacteria normally found in abundance on healthy skin to the skin of those deficient in beneficial bacteria. The aim of this review is to discuss the currently available literature on biological tools that have the potential to manipulate the skin microbiota, with particular focus on bacteriocins, phage therapy, antibiotics, probiotics and targets of the gut-skin axis. This review will also address how the skin microbiota protects humans from invading pathogens in the external environment while discussing novel strategies to manipulate the skin microbiota to avoid and/or treat various disease states.

Measuring Earwax Cortisol Concentration using a non-stressful sampling method

BACKGROUND

"Short-term" samples are not the most appropriate for reflecting chronic cortisol concentration. Although hair is used for reflecting the systemic level of this hormone, its use as a "long-term" measure appears clinically problematic. Local and systemic stress and non-stress related factors may release cortisol that is accumulated in hair. Non-stressful earwax sampling methods may provide a more accurate specimen to measure chronic cortisol concentration.

METHODS

Earwax from both ears of 37 controls were extracted using a clinical procedure commonly associated with local pain. One month later, earwax from the left ear side was extracted using the same procedure, and earwax from the right ear side was more comfortably obtained, using a novel earwax self-sampling device. Participants also provided one centimetre of hair that represented the retrospective month of cortisol output, and one serum sample that reflected the effect of systemic stressors on cortisol levels. Earwax (ECC), Hair (HCC) and Serum (SCC) Cortisol Concentration were correlated and compared. Confounders' effect on cortisol levels were studied.

RESULTS

The highest levels of cortisol concentration were found in serum, and the lowest in hair (p < 0.01). Left-ECC was larger than Right-ECC (p = 0.03). Right-ECC was the only sample unaffected by confounders (all p > 0.05). A Pearson correlation showed that Right-ECC and HCC samples were moderately correlated between them (r = 0.39; p = 0.03).

CONCLUSIONS

The self-sampling device did not increase cortisol locally. It provided the cortisol level that was least likely to be affected by confounding factors over the previous month. ECC using the novel device might constitute another accurate, but more suitable and affordable specimen for measuring chronic cortisol concentration.