Plasma concentration of selected neuropeptides in patients suffering from psoriasis

Untangling the mess of CGRP levels as a migraine biomarker: an in-depth literature review and analysis of our experimental experience

BACKGROUND

Calcitonin gene-related peptide (CGRP) is the most promising candidate to become the first migraine biomarker. However, literature shows clashing results and suggests a methodological source for such discrepancies. We aimed to investigate some of these methodological factors to evaluate the actual role of CGRP as biomarker.

METHODS

Previous to the experimental part, we performed a literature review of articles measuring CGRP in migraine patients. Using our 399 bio-bank sera samples, we performed a series of experiments to test the validity of different ELISA kits employed, time of sample processing, long-term storage, sampling in rest or after moderate exercise. Analysis of in-house data was performed to analyse average levels of the peptide and the effect of sex and age.

RESULTS

Literature review shows the high variability in terms of study design, determination methods, results and conclusions obtained by studies including CGRP determinations in migraine patients. CGRP measurements depends on the method and specific kit employed, also on the isoform detected, showing completely different ranges of concentrations. Alpha-CGRP and beta-CGRP had median with IQR levels of 37.5 (28.2-54.4) and 4.6 (2.4-6.4)pg/mL, respectively. CGRP content is preserved in serum within the 24 first hours when samples are stored at 4°C after clotting and immediate centrifugation. Storages at -80°C of more than 6 months result in a decrease in CGRP levels. Moderate exercise prior to blood extraction does not modulate the concentration of the peptide. Age positively correlates with beta-CGRP content and men have higher alpha-CGRP levels than women.

CONCLUSIONS

We present valuable information for CGRP measurements in serum. ELISA kit suitability should be tested prior to the experiments. Alpha and beta-CGRP levels should be analysed separately as they can show different behaviours even within the same condition. Samples can be processed in a 24-h window if they have been kept in 4°C and should not be stored for more than 6 months at -80°C before assayed. Patients do not need to rest before the blood extraction unless they have performed a high-endurance exercise. For comparative studies, sex and age should be accounted for as these parameters can impact CGRP concentrations.

Sensory neurons: An integrated component of innate immunity

The sensory nervous system possesses the ability to integrate exogenous threats and endogenous signals to mediate downstream effector functions. Sensory neurons have been shown to activate or suppress host defense and immunity against pathogens, depending on the tissue and disease state. Through this lens, pro- and anti-inflammatory neuroimmune effector functions can be interpreted as evolutionary adaptations by host or pathogen. Here, we discuss recent and impactful examples of neuroimmune circuitry that regulate tissue homeostasis, autoinflammation, and host defense. Apparently paradoxical or conflicting reports in the literature also highlight the complexity of neuroimmune interactions that may depend on tissue- and microbe-specific cues. These findings expand our understanding of the nuanced mechanisms and the greater context of sensory neurons in innate immunity.

Contribution of cosmetic ingredients and skin care textures to emotions

OBJECTIVE

Emotions play an important role in consumers' perception of a sensory experience. The objective of this work was to investigate the ability of basic skin care formulas (i.e. without interference of odour, colour and packaging) and pillar ingredients (i.e. emollients and rheology modifiers) to elicit emotions. Another objective was to track, as claimed by neurocosmetics, the possible effect of formulas to trigger emotions from their direct biochemical effects on the skin.

METHODS

Standard methodologies were mobilized, combining subjective and behavioural parameters (i.e. verbatim, prosody and gesture). Sense and Story methodology based on a collection of metaphoric verbatim was conducted after an induction phase. In addition, an experimental electrophysiological real-time visualization method was tried as a first experience in cosmetics. Finally, the ability of formulations with emotional benefits to modulate the release of neuropeptides by sensory neurons was evaluated on a 3D human model (epidermis co-cultured with sensory neurons).

RESULTS

Skin care formulas were shown to play a role in emotional potential and the types of emotion generated, while changing one ingredient mostly acted on the intensity of the emotions. Verbatim provided contrasted answers depending on the protocol, highlighting the interest of non-verbal approaches to detect subtle effects. The in vitro model substantiated physiological effects of skin care formulas with emotional potential on human skin sensory neuron activity.

CONCLUSION

Emotions were impacted by the change in ingredients and were better captured through non-verbal methods.

The association between ACE inhibitors and psoriasis based on the drug-targeted Mendelian randomization and real-world pharmacovigilance analyses

BACKGROUND

Although a growing number of observational studies suggest that angiotensin-converting enzyme inhibitors (ACEIs) intake may be a risk factor for psoriasis, evidence is still insufficient to draw definitive conclusions.

RESEARCH DESIGN AND METHODS

Drug-targeted Mendelian randomization (DTMR) was used to analyze the causality between genetic proxied ACEIs and psoriasis. Furthermore, we performed a disproportionality analysis based on the FDA adverse event reporting system (FAERS) database to identify more suspicious subclasses of ACEIs.

RESULTS

Using two kinds of genetic proxy instruments, the present DTMR research identified genetic proxied ACEIs as risk factors for psoriasis. Furthermore, our disproportionality analysis revealed that ramipril, trandolapril, perindopril, lisinopril, and enalapril were associated with the risk of psoriasis, which validates and refines the findings of the DTMR.

CONCLUSIONS

Our integrative study verified that ACEIs, especially ramipril, trandolapril, perindopril, lisinopril, and enalapril, tended to increase the risk of psoriasis statistically.

Effects of Neuropeptides on Dendritic Cells in the Pathogenesis of Psoriasis

Psoriasis is an autoimmune disease that is characterized by discolored, scaled patches of skin. Clinically, it is found that psychological factors often induce or aggravate the disease. Current research suggests that the pathogenesis of psoriasis involves the nervous and immune systems. This article reviews how neuropeptides secreted by nerve fibers affect dendritic cells in psoriasis. In this review, we describe that the neuropeptides calcitonin gene-related peptide, substance P, and vasoactive intestinal peptide can act on dendritic cells and participate in the pathogenesis of psoriasis. These neuropeptides can affect the secretion of interleukin (IL)-12 and IL-23 by dendritic cells, which stimulate T helper (Th)1, Th17, and Th22 cells to produce immune responses and cause the manifestation of psoriasis. The application of neuropeptide inhibitors can improve the skin lesions of psoriasis, which has been confirmed in clinical trials. Therefore, neuroimmune response may be a new direction to develop new drug treatments and perspectives in the development of psoriasis.

Migraine and obesity: what is the real direction of their association?

INTRODUCTION

In recent decades, studies have addressed the issue of how migraine and obesity are related and have suggested obesity as a risk factor for migraine headache. However, the exact direction of this relationship remains under debate. In this review, the authors summarize the evidence that have suggested migraine as a risk factor for obesity and overweightness.

AREAS COVERED

This article reviews the results of the previous research published on PubMed and Scopus databases (from 2000 to 2020) concerning the association between migraine and obesity to determine the actual direction of their association. Special attention has been given to the common mechanistic pathways involved in the pathophysiology of migraine and obesity.

EXPERT OPINION

The majority of research conducted thus far has considered obesity as a risk factor for migraine. However, because of the cross-sectional design of available research, we cannot be certain of the proposed direction of this association. There is evidence supporting the hypothesis that obesity can serve as a consequence of migraine through the effects of neuropeptides, inflammatory mediators, adipokines, gut microbiota and modifications in eating behavior and lifestyle. However, the real direction of the relationship between migraine and obesity should be further investigated in large prospective studies.

Soluble mediators in the function of the epidermal-immune-neuro unit in the skin

Skin is the largest, environmentally exposed (barrier) organ, capable of integrating various signals into effective defensive responses. The functional significance of interactions among the epidermis and the immune and nervous systems in regulating and maintaining skin barrier function is only now becoming recognized in relation to skin pathophysiology. This review focuses on newly described pathways that involve soluble mediator-mediated crosstalk between these compartments. Dysregulation of these connections can lead to chronic inflammatory diseases and/or pathologic conditions associated with chronic pain or itch.

Bariatric Surgery in Migraine patients: CGRP Level and Weight Loss

BACKGROUND

Obesity makes migraine more prevalent and severe. Serum level of calcitonin gene-related peptide (CGRP) is associated with the severity of migraine attacks. Although the effect of weight and bariatric surgery has been studied on migraine, the role of CGRP in migraine remission after weight loss surgery needs more investigation.

METHODS

Patients with severe obesity who were bariatric surgery candidates and had been diagnosed with chronic migraine were included in this study. Weight, BMI, number of days with headache in the past 3 months, and severity of headaches in 10-point Likert VAS, Migraine Disability Assessment Scale (MIDAS) and Migraine Specific Quality of life (MSQ) questionnaire scores, and serum CGRP levels were evaluated before and within 6-10 months after surgery.

RESULT

Sixty patients with chronic migraine with severe obesity were included. Ninety-five percent of patients reported a significantly lower number of attacks (21 to 8, p < 0.001) and severity of headaches within 90-day (7.7 to 4.8, p < 0.001); MIDAS (64.4 to 25.5, p < 0.001) and MSQ scores (44.6 to 26.8, p < 0.001) and CGRP level (252.7 to 130.1, p < 0.001) were significantly reduced after surgery with a mean follow-up of 7.5 months. Changes in MIDAS, MSQ, and CGRP were significantly associated with weight-related variables.

CONCLUSION

Bariatric surgery decreases the frequency of migraine attacks, lessens the severity of headaches, and improves the quality of life and disability as well as CGRP plasma levels, suggesting CGRP as a possible etiology in the migraine-obesity link.

Calcitonin gene-related peptide upregulates IL-17A and IL-22 in γδ-T cells through the paracrine effect of langerhans cells on LC/γδ-T co-culture model

Intense mental stimulation and stress often directly induce or exacerbate psoriasis. On the contrary, patients with nerve injury and nervous system dysfunction have psoriasis remission. The nervous system plays an important role in the inflammatory process of psoriasis, and neuropeptides are considered as local mediators of disease maintenance. To examine the molecular mechanism involved in this, first we analyzed calcitonin gene-related peptide (CGRP)-treated langerhans Cells and γδ-T cells separately. CGRP induced IL-23 mRNA and protein expression via PDK1-Rsk signaling pathway. However, CGRP had no effect on secretion of IL-17A and IL-22 in γδ-T cells. Then we treated LCs/γδ-T cells Co-culture Model with CGRP. CGRP upregulated IL-17A and IL-22 expression in co-culture model through the paracrine effect of LCs. IL-17A and IL-22 are key cytokines of psoriasis. These findings provide a potential mechanism by which nerve factors affect the development of psoriasis.

Regulation of Cutaneous Immunity In Vivo by Calcitonin Gene-Related Peptide Signaling through Endothelial Cells

Calcitonin gene-related peptide (CGRP) can bias the outcome of Ag presentation to responsive T cells in vitro away from Th1-type immunity and toward the Th2 and Th17 poles through actions on endothelial cells (ECs). To test the in vivo significance of this observation, we engineered a mouse lacking functional CGRP receptors on ECs (EC receptor activity modifying protein 1 [RAMP1] knockout mice). On percutaneous immunization to 1-fluoro-2,4-dinitrobenzene, stimulated CD4+ T cells from draining lymph nodes showed significantly reduced IL-17A expression with significantly increased IFN-γ, IL-4, and IL-22 expression at the protein and mRNA levels compared with control mice. Retinoic acid receptor-related orphan receptor γ t mRNA was significantly reduced, while mRNAs for T-box expressed in T cells and GATA binding protein 3 were significantly increased. In addition, EC RAMP1 knockout mice had significantly reduced contact hypersensitivity responses, and systemic administration of a CGRP receptor antagonist similarly inhibited contact hypersensitivity in wild-type mice. These observations provide compelling evidence that CGRP is a key regulator of cutaneous immunity through effects on ECs and suggest a novel pathway for potential therapeutic manipulation.

Lidocaine Ameliorates Psoriasis by Obstructing Pathogenic CGRP Signaling-Mediated Sensory Neuron-Dendritic Cell Communication

Psoriasis is a chronic immune-mediated skin disorder with the nervous system contributing to its pathology. The neurogenic mediators of psoriasis are elusive and whether the intervention of cutaneous nervous system can treat psoriasis remains to be determined. Here we conducted a pilot study using epidural injection of lidocaine to treat patients with psoriasis. Lidocaine treatment markedly reduced patients' clinical scores, and improved an imiquimod (IMQ)-induced rat model of psoriasis as competent as systemic delivery of a TNF-α antibody. IMQ application elicited aberrant cutaneous nerve outgrowth and excessive generation of neuropeptide calcitonin gene-related peptide (CGRP) from dorsal root ganglion (DRG) neurons, both of which were inhibited by epidural lidocaine treatment. Single-cell RNA sequencing unveiled the overrepresentation of CGRP receptors in dermal dendritic cell (DC) populations of patients with psoriasis. Through disturbing CGRP signaling, lidocaine inhibited IL-23 production by DCs co-cultured with DRG neurons. Thus, epidural nerve block with lidocaine demonstrates an effective therapy for psoriasis, which suppresses both inordinate sensory nerve growth in the inflamed skin and CGRP-mediated IL-23 production from psoriatic DCs.

CGRP measurements in human plasma - a methodological study

Background

Calcitonin gene-related peptide plasma levels have frequently been determined as a biomarker for primary headaches. However, published data is often inconsistent resulting from different methods that are not precisely described in most studies.

Methods

We applied a well-proven enzyme-linked immunosorbent assay to measure calcitonin gene-related peptide concentrations in human blood plasma, we modified parameters of plasma preparation and protein purification and used calcitonin gene-related peptide-free plasma for standard solutions, which are described in detail.

Results

Calcitonin gene-related peptide levels are stable in plasma with peptidase inhibitors and after deep-freezing. Calcitonin gene-related peptide standard solutions based on synthetic intercellular fluid or pooled plasma with pre-absorbed calcitonin gene-related peptide influenced the measurements but yielded both comprehensible results. In a sample of 56 healthy subjects the calcitonin gene-related peptide plasma levels varied considerably from low (<50 pg/mL) to very high (>500 pg/mL) values. After a 12-hour exposure of these subjects to normobaric hypoxia the individual calcitonin gene-related peptide levels remained stable.

Conclusion

Buffering with peptidase inhibitors and immediate freezing or processing of plasma samples is essential to achieve reliable measurements. Individuals show considerable differences and partly high calcitonin gene-related peptide plasma levels without detectable pathological reason. Thus plasma measurements are suited particularly to follow calcitonin gene-related peptide levels in longitudinal studies.

The use of data for this study was approved by the Ethics Committee of the Medical

University of Innsbruck (https://www.i-med.ac.at/ethikkommission/; EK Nr: 1242/2017).

Characteristics of Pruritus in Various Clinical Variants of Psoriasis: Results of the Multinational, Multicenter, Cross-Sectional Study

Psoriasis is a chronic, inflammatory skin disease present in about 3% of the world’s population. The clinical symptoms manifest diversely, therefore one can distinguish several subtypes of psoriasis. The majority of patients with psoriasis experience pruritus, which is an unpleasant sensation that decreases patients’ quality of life. The knowledge on pruritus in different subtypes of psoriasis is limited. We have performed a cross-sectional, prospective, and multicenter study to evaluate the relationship between clinical subtypes of psoriasis (large-plaque, nummular, guttate, palmoplantar, inverse, erythrodermic, palmoplantar pustular, generalized pustular psoriasis, and psoriasis of the scalp) and the prevalence, intensity, and clinical manifestation of itch. We introduced a questionnaire assessing various aspects of pruritus to a total of 254 patients. Out of these, 42 were excluded. Pruritus was present in 92.9% of the remaining patients and its prevalence did not depend on the clinical subtype. A correlation between the severity of psoriasis and the intensity of itch was explicitly noticeable in palmoplantar pustular psoriasis and scalp psoriasis (p < 0.05). The itch sensation was individual and differed among subtypes of psoriasis. In conclusion, pruritus is a frequent phenomenon, and its presentation is different in various subtypes of psoriasis.

The Role of TRPA1 in Skin Physiology and Pathology

The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, acts as 'polymodal cellular sensor' on primary sensory neurons where it mediates the peripheral and central processing of pain, itch, and thermal sensation. However, the TRPA1 expression extends far beyond the sensory nerves. In recent years, much attention has been paid to its expression and function in non-neuronal cell types including skin cells, such as keratinocytes, melanocytes, mast cells, dendritic cells, and endothelial cells. TRPA1 seems critically involved in a series of physiological skin functions, including formation and maintenance of physico-chemical skin barriers, skin cells, and tissue growth and differentiation. TRPA1 appears to be implicated in mechanistic processes in various immunological inflammatory diseases and cancers of the skin, such as atopic and allergic contact dermatitis, psoriasis, bullous pemphigoid, cutaneous T-cell lymphoma, and melanoma. Here, we report recent findings on the implication of TRPA1 in skin physiology and pathophysiology. The potential use of TRPA1 antagonists in the treatment of inflammatory and immunological skin disorders will be also addressed.

Resolvin D3 controls mouse and human TRPV1-positive neurons and preclinical progression of psoriasis

Rationale: Psoriasis is a chronic inflammatory disease caused by a complex interplay between the immune and nervous systems with recurrent scaly skin plaques, thickened stratum corneum, infiltration and activation of inflammatory cells, and itch. Despite an increasing availability of immune therapies, they often have adverse effects, high costs, and dissociated effects on inflammation and itch. Activation of sensory neurons innervating the skin and TRPV1 (transient receptor potential vanilloid 1) are emerging as critical components in the pathogenesis of psoriasis, but little is known about their endogenous inhibitors. Recent studies have demonstrated that resolvins, endogenous lipid mediators derived from omega-3 fatty acids, are potent inhibitors of TRP channels and may offer new therapies for psoriasis without known adverse effects. Methods: We used behavioral, electrophysiological and biochemical approaches to investigate the therapeutic effects of resolvin D3 (RvD3), a novel family member of resolvins, in a preclinical model of psoriasis consisting of repeated topical applications of imiquimod (IMQ) to murine skin, which provokes inflammatory lesions that resemble human psoriasis. Results: We report that RvD3 specifically reduced TRPV1-dependent acute pain and itch in mice. Mechanistically, RvD3 inhibited capsaicin-induced TRPV1 currents in dissociated dorsal root ganglion (DRG) neurons via the N-formyl peptide receptor 2 (i.e. ALX/FPR2), a G-protein coupled receptor. Single systemic administration of RvD3 (2.8 mg/kg) reversed itch after IMQ, and repeated administration largely prevented the development of both psoriasiform itch and skin inflammation with concomitant decreased in calcitonin gene-related peptide (CGRP) expression in DRG neurons. Accordingly, specific knockdown of CGRP in DRG was sufficient to prevent both psoriasiform itch and skin inflammation similar to the effects following RvD3 administration. Finally, we elevated the translational potential of this study by showing that RvD3 significantly inhibited capsaicin-induced TRPV1 activity and CGRP release in human DRG neurons. Conclusions: Our findings demonstrate a novel role for RvD3 in regulating TRPV1/CGRP in mouse and human DRG neurons and identify RvD3 and its neuronal pathways as novel therapeutic targets to treat psoriasis.

The Role of Nociceptive Neurons in the Pathogenesis of Psoriasis

Psoriasis is a chronic inflammatory skin disease. Emerging evidence shows that neurogenic inflammation, induced by nociceptive neurons and T helper 17 cell (Th17) responses, has a fundamental role in maintaining the changes in the immune system due to psoriasis. Nociceptive neurons, specific primary sensory nerves, have a multi-faceted role in detecting noxious stimuli, maintaining homeostasis, and regulating the immunity responses in the skin. Therefore, it is critical to understand the connections and interplay between the nociceptive neurons and the immune system in psoriasis. Here, we review works on the altered innervation that occurs in psoriasis. We examine how these distinct sensory neurons and their signal transducers participate in regulating inflammation. Numerous clinical studies report the dysfunction of nociceptive neurons in psoriasis. We discuss the mechanism behind the inconsistent activation of nociceptive neurons. Moreover, we review how neuropeptides, involved in regulating Th17 responses and the role of nociceptive neurons, regulate immunity in psoriasis. Understanding how nociceptive neurons regulate immune responses enhances our knowledge of the neuroimmunity involved in the pathogenesis of psoriasis and may form the basis for new approaches to treat it.

The JNK Signaling Pathway in Inflammatory Skin Disorders and Cancer

The c-Jun N-terminal kinases (JNKs), with its members JNK1, JNK2, and JNK3, is a subfamily of (MAPK) mitogen-activated protein kinases. JNK signaling regulates a wide range of cellular processes, including cell proliferation, differentiation, survival, apoptosis, and inflammation. Dysregulation of JNK pathway is associated with a wide range of immune disorders and cancer. Our objective is to provide a review of JNK proteins and their upstream regulators and downstream effector molecules in common skin disorders, including psoriasis, dermal fibrosis, scleroderma, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma.

Role of neuroimmune circuits and pruritus in psoriasis

Psoriasis is a chronic inflammatory skin disease presenting with an array of clinical phenotypes, often associated with pruritus. Environmental and psychological stressors can exacerbate psoriasis symptoms and provoke flares. Recent studies suggest a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis in some patients with psoriasis that can result in immune dysregulation. The immune system, in turn, can communicate with the nervous system to induce, maintain or aggravate psoriasis. In the skin, peripheral sensory as well as autonomic nerves control release of inflammatory mediators from dendritic cells, mast cells, T cells or keratinocytes, thereby modulating inflammatory responses and, in case of sensory nerves, pruritus. In response to the environment or stress, cytokines, chemokines, proteases, and neuropeptides fluctuate in psoriasis and influence immune responses as well as nerve activity. Furthermore, immune cells communicate with sensory nerves which control release of cytokines, such as IL-23, that are ultimately involved in psoriasis pathogenesis. Nerves also communicate with keratinocytes to induce epidermal proliferation. Notably, in contrast to recent years the debilitating problem of pruritus in psoriasis has been increasingly appreciated. Thus, investigating neuroimmune communication in psoriasis will not only expand our knowledge about the impact of sensory nerves in inflammation and pruritus and give new insights into the impact of environmental factors activating neuroimmune circuits or of stress in psoriasis, but may also lead to novel therapies. This review summarizes the relevant literature on the role of neuroimmune circuits, stress and how the central HPA axis and its peripheral equivalent in the skin, impact psoriasis.

Neurotransmitters, neuropeptides and their receptors interact with immune response in healthy and psoriatic skin

Psoriasis is a chronic inflammatory disease with a multifactorial origin that affects the skin. It is characterized by keratinocyte hyperproliferation, which results in erythemato-squamous plaques. Just as the immune system plays a fundamental role in psoriasis physiopathology, the nervous system maintains the inflammatory process through the neuropeptides and neurotransmitters synthesis, as histamine, serotonin, calcitonin gene-related peptide, nerve growth factor, vasoactive intestinal peptide, substance P, adenosine, glucagon-like peptide, somatostatin and pituitary adenylate cyclase polypeptide. In patients with psoriasis, the systemic or in situ expression of these chemical mediators and their receptors are altered, which affects the clinical activity of patients due to its link to the immune system, provoking neurogenic inflammation. It is important to establish the role of the nervous system since it could represent a therapeutic alternative for psoriasis patients. The aim of this review is to offer a detailed review of the current literature about the neuropeptides and neurotransmitters involved in the physiopathology of psoriasis.

Characteristics of Pruritus according to Morphological Phenotype of Psoriasis and Association with Neuropeptides and Interleukin-31

Background

Pruritus is a common symptom in psoriasis. However, few studies have assessed the characteristics of pruritus according to morphological phenotypes of psoriasis.

Objective

To investigate the characteristics of pruritus according to morphological phenotypes of psoriasis and to assess the association with inflammatory mediators related to pruritus.

Methods

Psoriasis patients were divided into 2 groups according to clinical phenotype: eruptive inflammatory (EI) and chronic stable (CS). Clinical data of pruritus were assessed by an itch questionnaire. Serum neuropeptides and cytokines including substance P, histamine, vasoactive intestinal peptide, neuropeptide Y, calcitonin gene-related peptide and interleukin-31 (IL-31) were quantitatively measured.

Results

In total, 50 patients with psoriasis (30 male, 20 female; mean age, 45.7 years) were studied (EI, n=15 and CS, n=35). Pruritus was reported by 80% of EI and CS patients. There were no significant differences in prevalence of pruritus, pruritus intensity, severity of psoriasis, serum neuropeptides, or IL-31 between the 2 groups.

Conclusion

The morphological phenotype does not seem to be an important factor affecting the prevalence and characteristics of pruritus in psoriasis.

Immunoregulatory Effects of Neuropeptides on Endothelial Cells: Relevance to Dermatological Disorders

Many skin diseases, including psoriasis and atopic dermatitis, have a neurogenic component. In this regard, bidirectional interactions between components of the nervous system and multiple target cells in the skin and elsewhere have been receiving increasing attention. Neuropeptides released by sensory nerves that innervate the skin can directly modulate functions of keratinocytes, Langerhans cells, dermal dendritic cells, mast cells, dermal microvascular endothelial cells and infiltrating immune cells. As a result, neuropeptides and neuropeptide receptors participate in a complex, interdependent network of mediators that modulate the skin immune system, skin inflammation, and wound healing. In this review, we will focus on recent studies demonstrating the roles of α-melanocyte-stimulating hormone, calcitonin gene-related peptide, substance P, somatostatin, vasoactive intestinal peptide, pituitary adenylate cyclase-activating peptide, and nerve growth factor in modulating inflammation and immunity in the skin through their effects on dermal microvascular endothelial cells.

Depression-Induced Neuropeptide Y Secretion Promotes Prostate Cancer Growth by Recruiting Myeloid Cells

PURPOSE

Psychologic depression has been shown to dysregulate the immune system and promote tumor progression. The aim of this study is to investigate how psychologic depression alters the immune profiles in prostate cancer.

EXPERIMENTAL DESIGN

We used a murine model of depression in Myc-CaP tumor-bearing immunocompetent FVB mice and Hi-myc mice presenting with spontaneous prostate cancer. Transwell migration and coculture assays were used to evaluate myeloid cell trafficking and cytokine profile changes evoked by Myc-CaP cells that had been treated with norepinephrine (NE), a major elevated neurotransmitter in depression. Chemoattractant, which correlated with immune cell infiltration, was screened by RNA-seq. The chemoattractant and immune cell infiltration were further confirmed using clinical samples of patients with prostate cancer with a high score of psychologic depression.

RESULTS

Psychologic depression predominantly promoted tumor-associated macrophage (TAM) intratumor infiltrations, which resulted from spleen and circulating monocytic myeloid-derived suppressor cell mobilization. Neuropeptide Y (NPY) released from NE-treated Myc-CaP cells promotes macrophage trafficking and IL6 releasing, which activates STAT3 signaling pathway in prostate cancer cells. Clinical specimens from patients with prostate cancer with higher score of depression revealed higher CD68⁺ TAM infiltration and stronger NPY and IL6 expression.

CONCLUSIONS

Depression promotes myeloid cell infiltration and increases IL6 levels by a sympathetic-NPY signal. Sympathetic-NPY inhibition may be a promising strategy for patients with prostate cancer with high score of psychologic depression.See related commentary by Mohammadpour et al., p. 2363.

Childhood trauma and resilience in psoriatic patients: A preliminary report

AIMS

Psoriasis is a chronic inflammatory skin disease with a complex etiology, involving the immune system, genetic factors, and external/internal triggers, with psychosomatic aspects. The aim of the study was to investigate childhood trauma and resilience in a psoriatic sample compared with healthy controls. Correlations between childhood trauma, resilience, quality of life, clinical data and psoriatic features were also evaluated.

METHODS

Seventy-seven psoriatic patients and seventy-six homogeneous healthy controls were enrolled. We used the Psoriasis Area and Severity Index (PASI) to assess the severity of psoriasis and the Skindex-29 to measure health-related quality of life. The psychometric battery included the Childhood Trauma Questionnaire (CTQ) and the Connor-Davidson Resilience Scale (CD-Risc) to assess trauma exposure and resilience, respectively.

RESULTS

Psoriatic patients showed a significant prevalence of childhood trauma and a lower resilience level compared to healthy controls. Associations between traumatic experiences, low resilience and reduced quality of life in psoriatic subjects were also observed.

CONCLUSIONS

A multidisciplinary approach is helpful to investigate clinical aspects, trigger factors and psychophysiological stress response in psoriatic subjects. Improving resilience with an early psychological intervention focused on self-motivation and strengthening of self-efficacy could facilitate the management of psoriasis.

[Pruritus in psoriasis : Profile and therapy]

Psoriasis is a common chronic inflammatory disease with an incidence of about 0.5-3 %. Previously psoriasis was not primarily regarded to be associated with pruritus; however, this perception has changed in recent years. Meanwhile data conclusively show that between 64 and 97 % of patients report about pruritus that can be severe in a number of cases. Apart from suffering from psoriasis, the presence of pruritus causes additional stress and leads to a significant impairment of health-related quality of life. Neurogenic inflammation at least in part contributes to the development of pruritus in psoriasis skin lesions. A number of neuropeptides including substance P and calcitonin gene related peptide can act as pro-inflammatory mediators. There is evidence for a dysbalance between κ‑ and µ‑opioid receptors in lesional skin favoring inflammation and pruritus. After clearing of psoriasis lesions, pruritus is relieved as well. Therefore, specific treatment of pruritus is not necessary in general. In cases where severe pruritus is a prominent symptom, targeted therapy with mirtazapin or doxepin or neuroleptic compounds such as pregabalin or gabapentin or drugs affecting the κ‑ und µ‑opioid receptor balance can be administered. Today the importance of pruritus as a prominent symptom of psoriasis lesions has been widely accepted. In recent and running clinical trials with new drugs, pruritus at baseline and the effect of these drugs on pruritus is always assessed. This awareness also fuels basic research about pruritus in psoriasis.

Upregulated expression of substance P in basophils of the patients with chronic spontaneous urticaria: induction of histamine release and basophil accumulation by substance P

Human basophils have been implicated in the pathogenesis of chronic spontaneous urticaria (CSU), and substance P (SP) is a possible candidate as histamine-releasing factor in some patients with CSU. However, little is known of relationship between basophils and SP in CSU. In the present study, we investigated expression of SP and NK1R on basophils from patients with CSU, and influence of SP on basophil functions by using flow cytometry analysis, basophil challenge, and mouse sensitization model techniques. The results showed that plasma SP level and basophil numbers in CSU patients were higher than that in HC subject. The percentages of SP+ and NK1R+ basophils were markedly elevated in CSU blood in comparison with HC blood. Once added, SP induced up to 41.2 % net histamine release from basophils of CSU patients, which was comparable with that provoked by anti-IgE, and fMLP. It appeared that SP induced dramatic increase in blood basophil numbers of mice following peritoneal injection. Ovalbumin (OVA)-sensitized mice had much more SP+ and NK1R+ basophils in blood than non-sensitized mice. In conclusion, the elevated plasma concentration of SP, upregulated expression of SP and NK1R on basophils, and the ability of SP in induction of basophil degranulation and accumulation indicate strongly that SP is most likely a potent proinflammatory mediator, which contributes greatly to the pathogenesis of CSU through basophils. Inhibitors of SP and blockers of NK1R are likely useful agents for treatment of CSU.

Calcitonin Gene-Related Peptide Reduces Taste-Evoked ATP Secretion from Mouse Taste Buds

Immunoelectron microscopy revealed that peripheral afferent nerve fibers innervating taste buds contain calcitonin gene-related peptide (CGRP), which may be as an efferent transmitter released from peripheral axon terminals. In this report, we determined the targets of CGRP within taste buds and studied what effect CGRP exerts on taste bud function. We isolated mouse taste buds and taste cells, conducted functional imaging using Fura-2, and used cellular biosensors to monitor taste-evoked transmitter release. The findings showed that a subset of Presynaptic (Type III) taste cells (53%) responded to 0.1 μm CGRP with an increase in intracellular Ca(2+). In contrast, Receptor (Type II) taste cells rarely (4%) responded to 0.1 μm CGRP. Using pharmacological tools, the actions of CGRP were probed and elucidated by the CGRP receptor antagonist CGRP(8-37). We demonstrated that this effect of CGRP was dependent on phospholipase C activation and was prevented by the inhibitor U73122. Moreover, applying CGRP caused taste buds to secrete serotonin (5-HT), a Presynaptic (Type III) cell transmitter, but not ATP, a Receptor (Type II) cell transmitter. Further, our previous studies showed that 5-HT released from Presynaptic (Type III) cells provides negative paracrine feedback onto Receptor (Type II) cells by activating 5-HT1A receptors, and reducing ATP secretion. Our data showed that CGRP-evoked 5-HT release reduced taste-evoked ATP secretion. The findings are consistent with a role for CGRP as an inhibitory transmitter that shapes peripheral taste signals via serotonergic signaling during processing gustatory information in taste buds.

SIGNIFICANCE STATEMENT

The taste sensation is initiated with a highly complex set of interactions between a variety of cells located within the taste buds before signal propagation to the brain. Afferent signals from the oral cavity are carried to the brain in chemosensory fibers that contribute to chemesthesis, the general chemical sensitivity of the mucus membranes in the oronasal cavities and being perceived as pungency, irritation, or heat. This is a study of a fundamental question in neurobiology: how are signals processed in sensory end organs, taste buds? More specifically, taste-modifying interactions, via transmitters, between gustatory and chemosensory afferents inside taste buds will help explain how a coherent output is formed before being transmitted to the brain.

Calcitonin gene-related peptide: key regulator of cutaneous immunity

Calcitonin gene-related peptide (CGRP) has been viewed as a neuropeptide and vasodilator. However, CGRP is more appropriately thought of as a pleiotropic signalling molecule. Indeed, CGRP has key regulatory functions on immune and inflammatory processes within the skin. CGRP-containing nerves are intimately associated with epidermal Langerhans cells (LCs), and CGRP has profound regulatory effects on Langerhans cell antigen-presenting capability. When LCs are exposed to CGRP in vitro, their ability to present antigen for in vivo priming of naïve mice or elicitation of delayed-type hypersensitivity is inhibited in at least some situations. Administration of CGRP intradermally inhibits acquisition of immunity to Th1-dominant haptens applied to the injected site while augmenting immunity to Th2-dominant haptens, although the cellular targets of activity in these experiments remain unclear. Although CGRP can be a pro-inflammatory agent, several studies have demonstrated that administration of CGRP can inhibit the elicitation of inflammation by inflammatory stimuli in vivo. In this regard, CGRP inhibits the release of certain chemokines by stimulated endothelial cells. This is likely to be physiologically relevant as cutaneous blood vessels are innervated by sensory nerves. Exciting new studies suggest a significant role for CGRP in the pathogenesis of psoriasis and, most strikingly, that CGRP inhibits the ability of LCs to transmit the human immunodeficiency virus 1 to T lymphocytes. A more complete understanding of the role of CGRP in the skin immune system may lead to new and novel approaches for the therapy of immune-mediated skin disorders.

Does psychosocial stress play a role in the exacerbation of psoriasis?

It is widely accepted that psychosocial stress can result from the daily strains of living with a diagnosis of psoriasis. There is now an evolving body of work to suggest that psychosocial stress may also play a role in the exacerbation of psoriasis. We discuss the historical evidence supporting a temporal relationship between psychosocial stress and the exacerbation of psoriasis. The underlying pathophysiological mechanisms by which this occurs are largely unknown, but current evidence points towards a role for nerve-related factors, namely their interaction with mast cells and the potentiation of neurogenic inflammation in this regard. It is also likely that the physiological stress response in patients with psoriasis differs from that in healthy individuals, as evidenced by alterations in the hypothalamic-pituitary-adrenal axis and sympathetic-adrenal-medullary system function. Psychological stress results in a redistribution of leucocytes with increased trafficking of inflammatory cells into the skin, which may exacerbate psoriasis. Langerhans cells play a role in the stress response of normal skin; their function in the stress response of patients with psoriasis is open to speculation. We discuss the influence of stress reactivity in patients with psoriasis and the impact of stress reduction strategies in the management of psoriasis. Finally, we suggest potentially fruitful areas for future research.

[Psychological and biological background of the correlation between psoriasis and stress]

Stress is considered as a major contributor to the development and exacerbation of psoriasis by a significant proportion of patients and dermatologists. As both stressor and its effects are subject-dependent, thus extremely difficult to measure, our understanding of the exact role of stress in disease development was limited for a long time. In the past decade several new studies were carried out which expanded our knowledge on the pathophysiologic processes linking stress to psoriasis via with their objective measurements and the applied new techniques. The authors review the current literature of both psychological (alexithymia, personality, affect) and biological (cortisol, epinephrine, neurogenic inflammation) factors influencing stress perception and response in psoriasis. Results of recent investigations support previous reports about the interaction between stress and psoriasis with objective evidence. Knowing how effective stress-reducing psychopharmacologic and psychotherapeutic interventions are in the treatment of psoriasis the authors hope that this review contributes to a wider acceptance of the psychosomatic attitude in everyday dermatologic practice.

Pathogenic value of neuropeptides and growth factor proteins for the development of inflammation and itching in patients with prevalent dermatoses

Goal. To determine the value of neuropeptides and growth factor proteins for the development of inflammation and itching in patients with atopic dermatitis and psoriasis. Materials and methods. There was a study of 13 patients with atopic dermatitis, 28 patients with psoriasis and eleven healthy volunteers. The severity and prevalence of the skin lesion in patients with atopic dermatitis was compared using the SCORAD score, and in psoriatic patients — using the PASI index. The extent of itching was assessed using a visual analog scale. The level of neuropeptides in blood serum of the subjects was determined using the enzyme-linked immunoelectrodiffusion assay: substance P and calcitonin gene-related peptide as well as nerve growth factor, amphiregulin, an epidermal growth factor, and semaphorin 3A, a nerve repulsion factor. Results. A statistically significant increase in the level of nerve growth factors in blood serum of patients with atopic dermatitis was observed (91.37 ± 16.39 pg/mL) vs. the control group (10.68 ± 8.37 pg/mL) (p < 0.05) as well as increased level of amphiregulin (46.09 ± 5.22 pg/mL) vs. the control group (10.21 ± 2.10) (p < 0.05). A positive correlation between the level of the nerve growth factor and SCORAD score was revealed. Conclusion. The results obtained confirm that nerve growth factors and amphiregulin are involved in the pathogenesis of atopic dermatitis.

Serum neurotensin (NT) is increased in psoriasis and NT induces vascular endothelial growth factor release from human mast cells

BACKGROUND

Psoriasis involves skin inflammation that often worsens with stress, but the mechanism of this effect remains obscure. We have shown that corticotropin-releasing hormone (CRH) is increased in the serum of patients with psoriasis. A peptide, neurotensin (NT), can trigger skin histamine release and augment the ability of CRH to increase skin vascular permeability.

OBJECTIVES

To investigate the serum level of NT, and the expression of genes for NT and NT receptor-1 (NTR-1) in lesional and nonlesional skin of patients with psoriasis, compared with normal controls. Also, to study the effect of NT on human mast cell release of vascular endothelial growth factor (VEGF), which is increased in psoriatic skin.

METHODS

Serum was obtained from patients with psoriasis (n = 56) and controls (n = 33); NT levels were measured with the Milliplex microbead assay. Biopsies were obtained from the lesional and nonlesional skin of patients with chronic plaque psoriasis (n = 40), who had not received any treatment for at least 15 days and were free of any systemic inflammatory diseases. Control skin samples were obtained from healthy subjects (n = 30). Expression of genes for NT and NTR-1 in the skin was evaluated by quantitative reverse transcriptase-polymerase chain reaction. LAD2 human mast cells were stimulated by NT (1 μmol L(-1)) for 24 h and VEGF was measured by enzyme-linked immunosorbent assay.

RESULTS

Serum NT was increased in patients with psoriasis, while expression of genes for NT and NTR-1 in lesional skin was decreased compared with controls. NT induced VEGF release from mast cells and was augmented by interleukin-33.

CONCLUSION

NT may play a role in psoriasis pathogenesis and its worsening by stress, at least in part through activation of skin mast cells.

Pathophysiology of the Behçet's Disease

Behçet's disease (BD) is a multisystemic disease of unknown etiology characterized by chronic relapsing oral-genital ulcers and uveitis. Multiple systemic associations including articular, gastrointestinal, cardiopulmonary, neurologic, and vascular involvement are also observed in BD. Although the etiopathogenesis of the disease remains unknown, increased neutrophil functions such as chemotaxis, phagocytosis, and excessive production of reactive oxygen species (ROS), including superoxide anion, which may be responsible for oxidative tissue damage seen in BD, and also immunological alterations, T lymphocyte abnormalities in both subpopulation and function have been considered to be correlated with the etiopathogenesis of BD. There is some clinical evidence suggesting that emotional stress and hormonal alterations can influence the course and disease activity of BD.

Keratinocyte expression of calcitonin gene-related peptide β: implications for neuropathic and inflammatory pain mechanisms

Calcitonin gene-related peptide (CGRP) is a vasodilatory peptide that has been detected at high levels in the skin, blood, and cerebrospinal fluid (CSF) under a variety of inflammatory and chronic pain conditions, presumably derived from peptidergic C and Aδ innervation. Herein, CGRP immunolabeling (IL) was detected in epidermal keratinocytes at levels that were especially high and widespread in the skin of humans from locations afflicted with postherpetic neuralgia (PHN) and complex region pain syndrome type 1 (CRPS), of monkeys infected with simian immunodeficiency virus, and of rats subjected to L5/L6 spinal nerve ligation, sciatic nerve chronic constriction, and subcutaneous injection of complete Freund's adjuvant. Increased CGRP-IL was also detected in epidermal keratinocytes of transgenic mice with keratin-14 promoter driven overexpression of noggin, an antagonist to BMP-4 signaling. Transcriptome microarray, quantitative Polymerase Chain Reaction (qPCR), and Western blot analyses using laser-captured mouse epidermis from transgenics, monolayer cultures of human and mouse keratinocytes, and multilayer human keratinocyte organotypic cultures, revealed that keratinocytes express predominantly the beta isoform of CGRP. Cutaneous peptidergic innervation has been shown to express predominantly the alpha isoform of CGRP. Keratinocytes also express the cognate CGRP receptor components, Calcitonin receptor-like receptor (CRLR), Receptor activity-modifying protein 1 (RAMP1), CGRP-receptor component protein (RCP) consistent with known observations that CGRP promotes several functional changes in keratinocytes, including proliferation and cytokine production. Our results indicate that keratinocyte-derived CGRPβ may modulate epidermal homeostasis through autocrine/paracrine signaling and may contribute to chronic pain under pathological conditions.

Calcitonin gene-related peptide: A molecular link between obesity and migraine?

Epidemiological studies have begun to suggest obesity is a risk factor for chronic migraine, although no causal relationship has been established and risk factors for progression from episodic to chronic migraine remain unknown. The neuropeptide calcitonin gene-related peptide (CGRP) plays a important role in the pathophysiology of migraine. Here, the potential role of CGRP as a molecular link between obesity and migraine is reviewed. A mechanistic association is supported by several lines of evidence: 1) common markers are elevated in obesity and migraine, 2) adipose tissue secretes proinflammatory cytokines and adipocytokines that have been implicated in migraine pathophysiology and 3) elevated levels of CGRP have been found in plasma of obese individuals. We propose that CGRP released from trigeminal neurons may represent a biological link between obesity and migraine. Enhanced trigeminal CGRP production in obese susceptible individuals may lower the threshold necessary to trigger migraine attacks, leading to more frequent episodes and eventually to chronic migraine.

IL-33 augments substance P-induced VEGF secretion from human mast cells and is increased in psoriatic skin

The peptide substance P (SP) has been implicated in inflammatory conditions, such as psoriasis, where mast cells and VEGF are increased. A relationship between SP and VEGF has not been well studied, nor has any interaction with the proinflammatory cytokines, especially IL-33. Here we report that SP (0.1-10 microM) induces gene expression and secretion of VEGF from human LAD2 mast cells and human umbilical core blood-derived cultured mast cells (hCBMCs). This effect is significantly increased by coadministration of IL-33 (5-100 ng/mL) in both cell types. The effect of SP on VEGF release is inhibited by treatment with the NK-1 receptor antagonist 733,060. SP rapidly increases cytosolic calcium, and so does IL-33 to a smaller extent; the addition of IL-33 augments the calcium increase. SP-induced VEGF production involves calcium-dependent PKC isoforms, as well as the ERK and JNK MAPKs. Gene expression of IL-33 and histidine decarboxylase (HDC), an indicator of mast cell presence/activation, is significantly increased in affected and unaffected (at least 15 cm away from the lesion) psoriatic skin, as compared with normal control skin. Immunohistochemistry indicates that IL-33 is associated with endothelial cells in both the unaffected and affected sites, but is stronger and also associated with immune cells in the affected site. These results imply that functional interactions among SP, IL-33, and mast cells leading to VEGF release contribute to inflammatory conditions, such as the psoriasis, a nonallergic hyperproliferative skin inflammatory disorder with a neurogenic component.

Vasoactive intestinal peptide attenuates concanavalin A-mediated liver injury

Vasoactive intestinal peptide (VIP) is well characterized as an endogenous anti-inflammatory neuropeptide and has a brand range of biological functions. In this study, we found increased endogenous VIP expression in mice with concanavalin A-induced hepatitis, a widely used experimental model of immune-mediated liver injury. We investigated further the effect of VIP administration on concanavalin A-induced liver injury. Compared with mice pretreated with PBS, mice pretreated with VIP exhibited much lower plasma levels of aminotransferases, less inflammatory infiltration in the liver and hepatocyte apoptosis. Meanwhile, VIP significantly inhibited the release of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in concanavalin A-injected mice, but markedly elevated the production of anti-inflammatory cytokine interleukine-10 (IL-10). Further investigation demonstrated increased intracellular cAMP concentration after VIP administration, and showed that the protective effect of VIP on concanavalin A-induced hepatitis was mediated mainly through VIP receptor 1 (VPAC(1)). These results suggest that VIP is capable of attenuating immune-mediated liver injury in vivo. This effect is associated with its downregulation of critical inflammatory mediators and its upregulation of anti-inflammatory cytokine through VPAC(1), possibly via the cAMP-dependent pathway.

Self-sustaining pathological processes in skin psoriasis

Clinical findings suggest that an etiological factor of skin psoriasis (SPs) is of nervous origin. Vasoactive intestinal peptide (VIP) is the most probable candidate for such a factor since VIP is the only neurotransmitter the extracellular level of which increases during SPs exacerbation and decreases in remission. VIP released from skin nerves induces keratinocyte hyperproliferation, angiogenesis, vasodilation, and other SPs-associated cutaneous pathological processes. These can go on over a prolonged period since (1) once released, VIP induces its own further secretion; (2) VIP induces release of interleukin-6 (IL6) that evokes both its own further release and release of VIP. Thereby, a vicious circle-type mechanism perpetuating and amplifying VIP secretion can function in the focuses of psoriatic damage. The mechanism described operates still more intensively under the effects of parathyroid hormone, aldosterone, and enkephalin, the blood levels of which are elevated in patients with SPs. The above explains such features of SPs as its association with human immunodeficiency virus infection, mental stress, alcohol consumption, smoking, and dependence of SPs on skin pigmentation.

Mediators of pruritus in psoriasis

The pathogenesis of pruritus in psoriasis remains unclear. Many possible mediators were implicated to transmit or modulate this sensation in psoriasis, but none has been clearly proven to be a causative agent of itching. The most often discussed theory mentioned the importance of impaired innervations and neuropeptides imbalance in psoriatic skin. Other possible causes of itching might be increased expression of interleukin 2 or vascular abnormalities. Recent data indicated that pruritus could be also evoked by opioid system, prostanoids, interleukin 31, serotonin, or proteases. Whether these mechanisms are also involved in pruritus accompanying psoriasis requires further investigation. Limited knowledge of pruritus origin in psoriasis is responsible for the lack of the effective antipruritic treatments for psoriatics. Here, we summarize the current knowledge about the pathogenesis of pruritus in psoriasis and point out possible directions of future studies aiming the pathogenesis of this symptom in psoriasis.