The role of neuropeptides in psoriasis

The Role of Epigenetic Factors in the Pathogenesis of Psoriasis

Psoriasis is a chronic inflammatory skin disease, the prevalence of which is increasing. Genetic, genomic, and epigenetic changes play a significant role in the pathogenesis of psoriasis. This review summarizes the impact of epigenetics on the development of psoriasis and highlights challenges for the future. The development of epigenetics provides a basis for the search for genetic markers associated with the major histocompatibility complex. Genome-wide association studies have made it possible to link psoriasis to genes and therefore to epigenetics. The acquired knowledge may in the future serve as a solid foundation for developing newer, increasingly effective methods of treating psoriasis. In this narrative review, we discuss the role of epigenetic factors in the pathogenesis of psoriasis.

Electroacupuncture on Baihui (DU20) and Xuehai (SP10) acupoints alleviates psoriatic inflammation by regulating neurotransmitter substance P- Neurokinin-1 receptor signaling

Background

At present, acupuncture-related practices have been widely used to treat psoriasis. In our study, we investigated the effect and explored the mechanism of electroacupuncture (EA) on acupoints Baihui (DU20) and Xuehai (SP10) for the treatment of psoriasis.

Methods

Imiquimod-induced psoriasis-like mouse model was used in this study. Mice were treated with electroacupuncture at DU20 and SP10 (depth of 2-3 mm, frequency of 2/15 Hz, intensity of 0.5-1.0 mA, 10 min/day). The severity of psoriasis-like lesions for each group was assessed. In addition, histological analysis of the lesions were performed. The levels of inflammatory cytokines were determined using Elisa. The expression levels of Substance P (SP) and NK1R were measured using Western blotting. In addition, NK1R inhibitor was administrated to evaluate the target of electroacupuncture in our mouse model.

Results

Electroacupuncture significantly alleviated IMQ-induced skin lesions and epidermal thickness, accompanied with reduced keratinocyte proliferation, CD3+, CD4+, and CD8+ T cells infiltration. The reduced levels of inflammatory cytokines was observed after electroacupuncture treatment. In addition, electroacupuncture inhibited the expression levels of SP and NK1R. NK1R inhibitor could ameliorate lesional symptoms and suppress epidermal thickening and CD3+, CD4+, and CD8 + T cell infiltration.

Conclusions

Electroacupuncture relieved psoriasis-like inflammation and T cell infiltration. This therapeutic action was likely mediated by the modulation of Substance P and its receptor NK1R.

Human Mast Cells Upregulate Cathepsin B, a Novel Marker of Itch in Psoriasis

Mast cells (MCs) contribute to skin inflammation. In psoriasis, the activation of cutaneous neuroimmune networks commonly leads to itch. To dissect the unique contribution of MCs to the cutaneous neuroinflammatory response in psoriasis, we examined their density, distribution, relation to nerve fibres and disease severity, and molecular signature by comparing RNA-seq analysis of MCs isolated from the skin of psoriasis patients and healthy volunteers. In involved psoriasis skin, MCs and Calcitonin Gene-Related Peptide (CGRP)-positive nerve fibres were spatially associated, and the increase of both MC and nerve fibre density correlated with disease severity. Gene set enrichment analysis of differentially expressed genes in involved psoriasis skin showed significant representation of neuron-related pathways (i.e., regulation of neuron projection along with dendrite and dendritic spine morphogenesis), indicating MC engagement in neuronal development and supporting the evidence of close MC-nerve fibre interaction. Furthermore, the analysis of 208 identified itch-associated genes revealed that CTSB, TLR4, and TACR1 were upregulated in MCs in involved skin. In both whole-skin published datasets and isolated MCs, CTSB was found to be a reliable indicator of the psoriasis condition. Furthermore, cathepsin B+ cells were increased in psoriasis skin and cathepsin B+ MC density correlated with disease severity. Therefore, our study provides evidence that cathepsin B could serve as a common indicator of the MC-dependent itch signature in psoriasis.

Psoriasis: Striving for Potential Biomarkers

Psoriasis is a chronic disease that is caused by multiple factors and is identified by itchiness, unpleasant, red, or white scaly patches on the skin, particularly on regularly chafed body regions such as the lateral areas of the limbs. Reports suggest that globally around 2%-3% of the population suffers from psoriasis. In this review, we have discussed the clinical classification of psoriasis and also the ideal characteristics of the biomarkers. An overview regarding the discovery of the biomarker and method for validating the study has been discussed. A growing body of research suggests a link to certain other systemic symptoms such as cardiovascular disorder, metabolic syndrome, and few other comorbidities such as hypertension and nonalcoholic fatty liver disease. Natural killer (NK) cells are lymphocyte cells that concentrate on the destruction of virally infected and malignant cells; these tend to produce a wide range of inflammatory cytokines, some of which are associated with the etiology of psoriasis. Detailed information on the molecular pathogenesis of psoriasis in which interleukin (IL)-17, IL-23, tumor necrosis factor-α (TNF-α), and CCL20 play a very significant role in the development of psoriasis. In this review, we have discussed an overview of the recent state of the biomarkers available for the diagnosis and treatment of psoriasis by emphasizing on the available biomarkers such as epigenomic, transcriptomic, glycomic, and metabolomic. The most recent advancements in molecular-targeted therapy utilizing biologics and oral systemic therapy (methotrexate, apremilast) enable to adequately treat the most serious psoriatic symptoms and also the studies have validated the efficacy of biologic therapy such as TNF-α antagonist (infliximab, adalimumab), IL-23 antagonist (guselkumab, risankizumab), and IL-17 antagonist (secukinumab, ixekizumab). Finally, an overview about the technological opportunities as well as various challenges has been discussed.

Nerve growth factor mediates activation of transient receptor potential vanilloid 1 in neurogenic pruritus of psoriasis

Pruritus is a common and painful symptom in psoriasis with profoundly negative impacts on quality of life. The underlying mechanisms of pruritus are complex and multifactorial, and accumulating evidence suggests that pruritus induced by neurogenic inflammation predominates in psoriasis. Nerve growth factor (NGF) -mediated transient receptor potential vanilloid receptor 1(TRPV1) pathway has emerged as a crucial node in the regulation of neurogenic pruritus. TRPV1 appears coupled to most pruritus-specific molecules via the neuro-immune axis. While the modes of regulation differ for each axis, TRPV1 is involved in substantial biochemical crosstalk-causing feedback loops with significant effects on neurogenic pruritus. Therefore, TRPV1 has emerged as a target molecular in drug development for pruritus in psoriasis. However, no significant clinical progress occurred in the development of systemic TRPV1 antagonists due to elevated core temperature. Thus, topical application of TRPV1 antagonists and interference with mediators linked to the TRPV1 activation pathway may be promising therapeutic options to ameliorate pruritus. This Review focuses on recent advances in complicated regulation of NGF-mediated TRPV1 pathway in psoriatic neurogenic pruritus, as well as the therapeutic options that arise from the dissection of the pathway.

Effects of pulsed dye laser treatment in psoriasis: A nerve-wrecking process?

Pulsed dye laser (PDL) therapy can be effective in treating psoriasis, with a long duration of remission. Although PDL therapy, albeit on a modest scale, is being used for decades now, the underlying mechanisms responsible for the long-term remission of psoriasis remain poorly understood. The selective and rapid absorption of energy by the blood causes heating of the vascular wall and surrounding structures, like perivascular nerves. Several studies indicate the importance of nerves in psoriatic inflammation. Interestingly, denervation leads to a spontaneous remission of the psoriatic lesion. Among all dermal nerves, the perivascular nerves are the most likely to be affected during PDL treatment, possibly impairing the neuro-inflammatory processes that promote T-cell activation, expression of adhesion molecules, leukocyte infiltration and cytokine production. Repeated PDL therapy could cause a prolonged loss of innervation through nerve damage, or result in a 'reset' of neurogenic inflammation after temporary denervation. The current hypothesis provides strong arguments that PDL treatment affects nerve fibres in the skin and thereby abrogates the persistent and exaggerated inflammatory process underlying psoriasis, causing a long-term remission of psoriasis.

Evaluation of the relationship between migraine and psoriasis: a case-control study

BACKGROUND

Although several recent studies have attempted to describe the association between psoriasis and migraine, there is little data in this regard.

OBJECTIVE

To explore the relationship between migraine and psoriasis.

METHODS

A total of 312 patients with psoriasis and 312 age- and gender-matched controls without psoriasis were recruited in this case-control study. Based on the diagnosis of migraine, they were divided into 4 subgroups: psoriasis with (PM+) and without (PM-) migraine, and control with (CM+) and without migraine (CM-). The subgroups were compared regarding the migraine and psoriasis characteristics.

RESULTS

The mean (SD) age of patients and controls (139 males, in each group) was 43.2 (13.2) years. Psoriasis patients were significantly more likely to have migraine (OR = 2.789). Migraine with aura was significantly higher in the PM + group than in the CM + group (p = 0.007). The mean PASI score (p = 0.001), frequency of moderate and severe psoriasis (p = 0.048), and frequency of patients with PsA (p < 0.001) were significantly higher in PM + compared to PM-. The risk of migraine substantially increased with increasing psoriasis severity (OR = 2.062, OR = 3.248, and OR = 4.586 for mild, moderate, and severe, respectively), and with the presence of PsA (OR = 2.438 and OR = 12.930 for patients without and with PsA, respectively).

STUDY LIMITATIONS

Observational nature, not including all confounding factors, not addressing a cause-and-effect relationship.

CONCLUSIONS

In comparison with the non-psoriatic control group, psoriasis patients are predisposed to a significantly higher risk of migraine, particularly migraine with aura, psoriasis patients with more severe disease and those with PsA have a markedly higher risk of having migraine, and the migraine headache index is significantly higher in psoriasis patients.

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.

How Does Botulinum Toxin Inhibit Itch?

Two decades after reports of the anti-pruritic effects of botulinum neurotoxins (BoNTs), there is still no approved product for the anti-itch indication of BoNTs, and most clinical case reports still focus on the off-label use of BoNTs for various itchy conditions. Few randomized clinical trials have been conducted with controversial results, and the beneficial effects of BoNTs against itch are mainly based on case studies and case series. These studies are valuable in presenting the potential application of BoNTs in chronic pruritic conditions, but due to the nature of these studies, they are categorized as providing lower levels of evidence or lower grades of recommendation. To obtain approval for the anti-pruritic indication of BoNTs, higher levels of evidence are required, which can be achieved through conducting large-scale and well-designed studies with proper control groups and established careful and reliable primary and secondary outcomes. In addition to clinical evidence, presenting the mechanism-based antipruritic action of BoNTs can potentially strengthen, accelerate, and facilitate the current efforts towards further investments in accelerating the field towards the potential approval of BoNTs for itchy conditions. This review, therefore, aimed to provide the state-of-the-art mechanisms underlying the anti-itch effect of BoNTs from basic studies that resemble various clinical conditions with itch as a hallmark. Evidence of the neuronal, glial, and immune modulatory actions of BoNTs in reducing the transmission of itch are presented, and future potential directions are outlined.

Botulinum Toxin Use for Modulating Neuroimmune Cutaneous Activity in Psoriasis

Psoriasis is a complex immune-mediated inflammatory disorder that generates enormous interest within the scientific communities worldwide, with new therapeutic targets being constantly identified and tested. Despite the numerous topical and systemic medications available for the treatment of psoriasis, alternative therapies are still needed for the optimal management of some patients who present with localized, resistant lesions. Novel insights into the contribution of cutaneous neurogenic inflammation in the pathogenesis of psoriasis have yielded exciting new potential roles of nerve-targeting treatments, namely botulinum toxin type A (BoNT-A), for the management of this disease. This paper aims to review the existing literature on knowledge regarding the potential role of BoNT-A in psoriasis treatment, with a focus on its ability to interfere with the immunopathogenetic aspects of psoriatic disease. Furthermore, in our paper, we are also including the first report of psoriatic lesions remission following local BoNT-A injections that were administered for treating upper limb spasticity, in a patient that concomitantly suffered from psoriasis and post-stroke spasticity.

The Trinity of Skin: Skin Homeostasis as a Neuro–Endocrine–Immune Organ

For a long time, skin was thought to be no more than the barrier of our body. However, in the last few decades, studies into the idea of skin as an independent functional organ have gradually deepened our understanding of skin and its functions. In this review, we gathered evidence that presented skin as a “trinity” of neuro–endocrine–immune function. From a neuro perspective, skin communicates through nerves and receptors, releasing neurotrophins and neuropeptides; from an endocrine perspective, skin is able to receive and secrete most hormones and has the cutaneous equivalent of the hypothalamic-pituitary-adrenal (HPA) axis; from an immune perspective, skin is protected not only by its physical barrier, but also immune cells and molecules, which can also cause inflammation. Together as an organ, skin works bidirectionally by operating peripheral neuro–endocrine–immune function and being regulated by the central nervous system, endocrine system and immune system at the same time, maintaining homeostasis. Additionally, to further explain the “trinity” of cutaneous neuro–endocrine–immune function and how it works in disease pathophysiology, a disease model of rosacea is presented.

Sleep Disorders and Psoriasis: An Update

Psoriasis alters patients’ quality of life. Among the disorders associated with psoriasis, sleep disorders are common, although they are not directly assessed by most quality-of-life scores. Thus, the specific evaluation of sleep disorders using dedicated scores is necessary, especially because such disorders alter patients;’ physical and psychological health. The relationship between psoriasis and sleep disorders has been shown in numerous studies, but has not yet been fully elucidated. The aim of this study was to update knowledge of sleep disorders in patients with psoriasis, through a review of the scientific literature since 1980. This work covers several topics of interest, such as sleep assessment methods, the prevalence of sleep disorders in patients with psoriasis, factors predictive of sleep disorders in patients with psoriasis, the impact of sleep disorders on comorbidities and quality of life, pathogenic mechanisms, obstructive sleep apnoea and restless leg syndromes, and the impact of biotherapy treatments on sleep disorders in patients with psoriasis.

Pruritus: A Sensory Symptom Generated in Cutaneous Immuno-Neuronal Crosstalk

Pruritus or itch generated in the skin is one of the most widespread symptoms associated with various dermatological and systemic (immunological) conditions. Although many details about the molecular mechanisms of the development of both acute and chronic itch were uncovered in the last 2 decades, our understanding is still incomplete and the clinical management of pruritic conditions is one of the biggest challenges in daily dermatological practice. Recent research revealed molecular interactions between pruriceptive sensory neurons and surrounding cutaneous cell types including keratinocytes, as well as resident and transient cells of innate and adaptive immunity. Especially in inflammatory conditions, these cutaneous cells can produce various mediators, which can contribute to the excitation of pruriceptive sensory fibers resulting in itch sensation. There also exists significant communication in the opposite direction: sensory neurons can release mediators that maintain an inflamed, pruritic tissue-environment. In this review, we summarize the current knowledge about the sensory transduction of pruritus detailing the local intercellular interactions that generate itch. We especially emphasize the role of various pruritic mediators in the bidirectional crosstalk between cutaneous non-neuronal cells and sensory fibers. We also list various dermatoses and immunological conditions associated with itch, and discuss the potential immune-neuronal interactions promoting the development of pruritus in the particular diseases. These data may unveil putative new targets for antipruritic pharmacological interventions.

Transcriptional Analysis-Based Alterations Affecting Neuritogenesis of the Peripheral Nervous System in Psoriasis

An increasing amount of evidence indicates the critical role of the cutaneous nervous system in the initiation and maintenance of psoriatic skin lesions by neurogenic inflammation. However, molecular mechanisms affecting cutaneous neurons are largely uncharacterized. Therefore, we reanalyzed a psoriatic RNA sequencing dataset from published transcriptome experiments of nearly 300 individuals. Using the Ingenuity Pathway Analysis software, we associated several hundreds of differentially expressed transcripts (DETs) to nervous system development and functions. Since neuronal projections were previously reported to be affected in psoriasis, we performed an in-depth analysis of neurite formation-related process. Our in silico analysis suggests that SEMA-PLXN and ROBO-DCC-UNC5 regulating axonal growth and repulsion are differentially affected in non-lesional and lesional skin samples. We identified opposing expressional alterations in secreted ligands for axonal guidance signaling (RTN4/NOGOA, NTNs, SEMAs, SLITs) and non-conventional axon guidance regulating ligands, including WNT5A and their receptors, modulating axon formation. These differences in neuritogenesis may explain the abnormal cutaneous nerve filament formation described in psoriatic skin. The processes also influence T-cell activation and infiltration, thus highlighting an additional angle of the crosstalk between the cutaneous nervous system and the immune responses in psoriasis pathogenesis, in addition to the known neurogenic pro-inflammatory mediators.

Topical Treatment of Colquhounia Root Relieves Skin Inflammation and Itch in Imiquimod-Induced Psoriasiform Dermatitis in Mice

Itch is one of the major clinical manifestations of psoriasis, which is closely related with neurogenic inflammation and difficult to control. Colquhounia Root (CR) is a Chinese herb exhibiting broad bioactivities on anti-inflammation. This study was designed to explore the antipsoriatic and anti-itch potential of CR and its underlying mechanisms. Mice in a model of imiquimod-induced psoriasiform dermatitis were treated topically with CR for 7 days, and the severity of skin lesions and itch was significantly ameliorated. CR reduced the inflammatory cell infiltration, as well as mast cells in skins. Particularly, the expression of inflammatory cytokines and chemokine including Il17a, Il22, and Ccl20 and itch-related molecules such as SP, CGRP, and NGF in lesions were decreased in diseased mice upon application with CR. The normal human epidermal keratinocytes were stimulated with the M5 cytokine cocktail, the mixture of IL-17A, IL-22, Oncostatin M, IL-1α, and TNF-α, and cell viability and mRNA expression levels of inflammatory factors and itch-related molecules were measured after being treated with CR. We found that CR inhibited both cell hyperproliferation and overexpression of inflammatory cytokines and itch-related molecules in vitro. Altogether, we conclude that CR relieves psoriatic lesions and itch via controlling immunological and neurogenic inflammation.

The Role of Interleukins in the Pathogenesis of Dermatological Immune-Mediated Diseases

Autoimmune inflammatory diseases are primarily characterized by deregulated expression of cytokines, which drive pathogenesis of these diseases. A number of approved and experimental therapies utilize monoclonal antibodies against cytokine proteins. Cytokines can be classified into different families including the interleukins, which are secreted and act on leukocytes, the tumor necrosis factor (TNF) family, as well as chemokine proteins. In this review article, we focus on the interleukin family of cytokines, of which 39 members have been identified to this date. We outline the role of each of these interleukins in the immune system, and various dermatological inflammatory diseases with a focused discussion on the pathogenesis of psoriasis and atopic dermatitis. In addition, we describe the roles of various interleukins in psychiatric, cardiovascular, and gastrointestinal comorbidities. Finally, we review clinical efficacy and safety data from emerging late-phase anti-interleukin therapies under development for psoriasis and atopic dermatitis. Collectively, additional fundamental and clinical research remains necessary to fully elucidate the roles of various interleukin proteins in the pathogenesis of inflammatory dermatologic diseases, and treatment outcomes in patients.

Peripheral Mechanisms of Itch

Itch is a universally experienced sensation, and chronic itch can be as diabolically debilitating as pain. Recent advances have not only identified the neuronal itch sensing circuitry, but also have uncovered the intricate interactions between skin and immune cells that work together with neurons to identify itch-inducing irritants. In this review, we will summarize the fundamental mechanisms of acute itch detection in the skin, as well as highlight the recent discoveries relating to this topic.

Roles of calcitonin gene-related peptide in the skin, and other physiological and pathophysiological functions

Skin immunity is regulated by many mediator molecules. One is the neuropeptide calcitonin gene-related peptide (CGRP). CGRP has roles in regulating the function of components of the immune system including T cells, B cells, dendritic cells (DCs), endothelial cells (ECs), and mast cells (MCs).

Herein we discuss actions of CGRP in mediating inflammatory and vascular effects in various cutaneous models and disorders.

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CGRP can help to recruit immune cells through endothelium-dependent vasodilation.

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CGRP plays an important role in the pathogenesis of neurogenic inflammation.

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Functions of many components in the immune system are influenced by CGRP.

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CGRP regulates various inflammatory processes in human skin by affecting different cell-types.

Maximizing the Utility of Transcriptomics Data in Inflammatory Skin Diseases

Inflammatory skin diseases are induced by disorders of the host defense system of the skin, which is composed of a barrier, innate and acquired immunity, as well as the cutaneous microbiome. These disorders are characterized by recurrent cutaneous lesions and intense itch, which seriously affecting life quality of people across all ages and ethnicities. To elucidate molecular factors for typical inflammatory skin diseases (such as psoriasis and atopic dermatitis), transcriptomic profiling assays have been largely performed. Additionally, single-cell RNA sequencing (scRNA-seq) as well as spatial transcriptomic profiling have revealed multiple potential translational targets and offered guides to improve diagnosis and treatment strategies for inflammatory skin diseases. High-throughput transcriptomics data has shown unprecedented power to disclose the complex pathophysiology of inflammatory skin diseases. Here, we will summarize discoveries from transcriptomics data and discuss how to maximize the transcriptomics data to propel the development of diagnostic biomarkers and therapeutic targets in inflammatory skin diseases.

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.

Capsaicin attenuates imiquimod-induced epidermal hyperplasia and cutaneous inflammation in a murine model of psoriasis

Psoriasis is one of the most common chronic inflammatory diseases that is characterized by well-defined erythematous plaques, with typical histopathological findings of lymphocytic infiltration and epidermal hyperplasia. Topical treatments of psoriasis are either associated with limited response or with side effects. Up to date, topicals targeting neuroimmune axis in psoriasis or psoriasiform dermatitis have not been explored. Here, we investigated whether percutaneous delivery of capsaicin could attenuate the pathological change of psoriasiform inflammation. Imiquimod-induced psoriasis-like murine model was used to evaluate therapeutic effects from topical application of capsaicin. An additional model of psoriasiform dermatitis induced by direct IL-23 injection was used to identify the level of action from capsaicin in this neuroimmune axis. Cutaneous inflammation was assessed by erythema level and ear thickness change. Key cytokines, infiltrating cells in the skin, and draining lymph node cells were investigated. The results showed that capsaicin administration obstructed the activation of IL-23/IL-17 pathway induced by imiquimod, presenting with significantly reduced psoriasiform dermatitis both in gross appearance and microscopic features. Tissue gene expression of psoriatic core cytokines induced by imiquimod (including IL-23, IL-17A, IL-22, TNF-α, and IL-6) were greatly decreased by capsaicin application. This protective effect from capsaicin could be hampered by direct intradermal injection of IL-23. CONCLUSION: Epicutaneous delivery of capsaicin on imiquimod-treated murine skin could significantly decrease expression of multiple inflammatory cytokines and the severity of prototypic change of psoriasiform inflammation. The beneficial effect imposed by capsaicin reinforces the neuroimmune contribution towards psoriasiform inflammation and provides a potential non-steroidal therapeutic alternative for topical treatment of psoriasiform dermatitis.

Human papillomavirus infection associated with increased risk of new-onset psoriasis: a nationwide population-based cohort study

BACKGROUND

This study investigated whether patients with a history of human papillomavirus (HPV) infection are at increased risk of developing psoriasis.

METHODS

We enrolled 66 274 patients with HPV infection between 1997 and 2013 from the Taiwan National Health Insurance Research Database, and compared them with control individuals who had never been diagnosed with HPV infection (at a 1:4 ratio matched by age, sex and index year) in relation to the risk of developing psoriasis. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), with the control group as reference.

RESULTS

The adjusted hazard ratio (aHR) was 1.177 (95% CI, 1.010-1.373) after adjusting for demographic characteristics, comorbidities, dermatology-related outpatient visits and medications. The HPV group had an increased risk of psoriasis compared with the control group in all of the different age groups. The P-value for interaction between age and exposure of HPV is 0.009 in our sub-group analysis.

CONCLUSIONS

A higher risk of psoriasis was found after HPV infection, and age acted as an effect modifier between the HPV infection and risk of psoriasis.

Pruritus in psoriasis and atopic dermatitis: current treatments and new perspectives

Psoriasis and atopic dermatitis (AD) are two common chronic inflammatory skin diseases. Although showing different etiology and clinical manifestations, patients with either disease suffer from low health-related quality of life due to pruritus (dermal itch). Recent studies have revealed that more than 85% of psoriasis patients suffer from pruritus, and it is also the dominating symptom of AD. However, as this is a non-life treating symptom, it was partly neglected for years. In this review, we focus on current findings as well as the impact and potential treatments of pruritus in these two skin diseases. We first distinguish the type of itch based on involved mediators and modulators. This clear delineation between the types of pruritus based on involved receptors and pathways allows for precise treatment. In addition, insights into recent clinical trials aimed to alleviate pruritus by targeting these receptors are presented. We also report about novel advances in combinatorial treatments, dedicated to the type of pruritus linked to a causal disease. Altogether, we suggest that only a focused treatment tailored to the primary disease and the underlying molecular signals will provide fast and sustained relief of pruritus associated with psoriasis or AD.

Molecular and Cellular Mechanisms of Itch in Psoriasis

Itch (or pruritus) was not previously recognized as a serious symptom of psoriasis. However, approximately 60-90% of psoriatic patients with pruritus have stated that it deteriorates their quality of life. Since conventional antipruritic therapies, such as antihistamines, only exert limited effects, the establishment of a treatment option for itch in psoriasis is urgently needed. Although a definitive drug is not currently available, various itch mediators are known to be involved in pruritus in psoriasis. In this review, we describe the clinical features of pruritus in psoriasis, classify a wide range of itch mediators into categories, such as the nervous, immune, endocrine, and vascular systems, and discuss the mechanisms by which these mediators induce or aggravate itch in the pathophysiology of psoriasis.

Suppression of neuropeptide by botulinum toxin improves imiquimod-induced psoriasis-like dermatitis via the regulation of neuroimmune system

BACKGROUND

Psoriasis is a multifactorial disease arises from a complex interaction of genetics, immune system, and environmental aspects. IL-23/Th17 immune axis has been considered as a primary modulator in psoriasis. In addition, several findings imply that nervous system may take a part in the pathogenesis of psoriasis, suggesting that nervous system, through its neuropeptide, may interact with immune system and lead to the formation of psoriasis.

OBJECTIVE

We aimed to ascertain the role of neuropeptides secreted from neurons in the pathogenesis of psoriasis in vivo.

METHODS

The release of neuropeptide was inhibited by injecting Botulinum toxin B (BTX-B) on Imiquimod (IMQ)-induced psoriasis-like dermatitis mice model. Quantification of skin dermatitis, infiltrating inflammatory cells, and the production of cytokines at the lesional skin area were performed by PSI score, immunostaining, and real-time PCR. We also tested the effect of selective CGRP antagonist (CGRP_8-37) on psoriasis-like dermatitis in IMQ-treated mice.

RESULTS

BTX-B injection significantly suppressed PSI score and reduced the number of CD4⁺ T cells, CD11c⁺ dendritic cells, and the production of IL-17A/F in the lesional skin. The expressions of PGP9.5⁺ nerve fibers and neuropeptides (SP, CGRP) were also significantly reduced following BTX-B injection. Additionally, CGRP antagonist also suppressed the development of IMQ-induced psoriasis-like dermatitis in mice.

CONCLUSION

The suppression of neuropeptide secretion in the skin by BTX injection might inhibit nerve elongation, the infiltration of immune cells, as well as IL-17 production, resulting in the improvement of psoriasis. Neuropeptide inhibitor could also be applied to the treatment of psoriasis.

Autoimmunity in Segmental Vitiligo

The autoimmune basis of segmental vitiligo (SV) has only recently been recognized. Systemic autoimmune diseases are less frequently associated compared to non-segmental vitiligo (NSV), but localized skin disorders - in particular linear morphea - have been repeatedly observed in patients with SV. The inflammatory response is documented on a clinical level with cases displaying erythematous borders or a hypochromic stage, on a histopathological level with predominantly CD8 lymphocytes migrating toward the basal layer and by flow cytometry demonstrating the antimelanocyte specificity of these cytotoxic T cells. The increased risk for halo naevi and NSV in these patients further underline the immune-mediated mechanisms of SV. Nonetheless, the localized and unique distribution pattern points to somatic mosaicism. This places SV in a category of similar diseases such as lichen striatus, blaschkitis, linear lupus erythematosus, and linear scleroderma where an immune reaction against genetically mutated skin cells is believed to be the underlying cause. All these disorders are characterized by a young age of onset, a temporary disease activity with spontaneous resolution, limited response to treatment, and often long-term sequelae. Although challenging, genetic research proving this genetic mosaicism could offer crucial insights into the pathogenesis of both segmental and non-segmental vitiligo.

Sensory Neuron-Expressed TRPC4 Is a Target for the Relief of Psoriasiform Itch and Skin Inflammation in Mice

Psoriasis is an inflammatory skin disease associated with itch, which is a troublesome symptom with a few therapeutic options. TRPC4 is highly expressed in dorsal root ganglia (DRGs). Recently, we have revealed itch signaling in DRG neurons by which TRPC4 mediates itch to serotonergic antidepressants and demonstrated the antipruritic effect of the TRPC4 inhibitor ML204. However, the role of TRPC4 in acute and chronic itch is still largely unknown. Here, we have characterized the expression of TRPC4 in peptidergic DRG neurons and showed that acute itch induced by serotonin and histamine was attenuated in Trpc4-knockout mice and ML204-treated mice. We have also shown that silencing TRPC4 in DRG and its inhibition by intradermal injections were also effective in decreasing psoriatic itch after the repeated application of imiquimod, which is a preclinical model of psoriasis. Of clinical relevance, intradermal injections of ML204 in psoriasiform skin significantly reversed imiquimod-established chronic itch and cutaneous inflammation. Given that TRPC4 is expressed in human DRGs and a specific inhibitor is in clinical trials, our data not only expand our understanding of itch and psoriasis, but also reveal TRPC4 as a potential therapeutic target with considerable translational benefits.

High-throughput transcriptome and pathogenesis analysis of clinical psoriasis

BACKGROUND

Previous psoriasis studies have mostly focused on skin-related immunology, but the exact mechanisms remain elusive. Clinical evidence, such as higher morbidity among obese individuals and emotional factors, indicate that psoriasis is a complex systemic disease. High-throughput transcriptome analysis provides an effective method to comprehensively assess the disease.

OBJECTIVE

The present study is aiming to understand transcriptome changes of clinical psoriasis skins and comprehensively assess the diseases using pathways analysis.

METHODS

We performed transcriptome sequence of clinical psoriatic samples. Biological pathway analyses were conducted using differentially expressed RNAs, as well as identified competing endogenous RNAs (ceRNAs). qRT-PCR and histological immunofluorescence staining was conducted to verify the differentially expressed RNAs (DE_RNAs) and the three important enriched biological pathways.

RESULTS

Numerous DE_RNAs were identified between psoriasis patients and healthy people. Functional analysis indicated PPAR-fatty acids metabolism pathways, neural-hormone regulations, circadian entrainment were the three mostly appeared pathways. For PPAR-fatty acids metabolism pathways, the expression of seven randomly selected genes, including ACSBG1, ACOT2), CYP27A1, ELOVL3, FABP7, FADS2 and PPARG were all significantly decreased in psoriasis lesions. For neural-hormone regulation pathways, the expression of CFL1, EPHA2, HRAS were all significantly upregulated in psoriasis lesions. While the expression of four randomly selected genes from circadian entrainment pathways, including CRY2, PER3, NR1D1 and RORC were all significantly downregulated. Histological immunofluorescence staining of FADS2, EPHA2 and CRY2 were consistent with their genes' expressions.

CONCLUSION

Our results revealed transcriptome changes of psoriasis, and indicated three important pathways involved in psoriasis, including PPAR-fatty acids metabolism pathways, neural-hormone regulations, circadian entrainment.

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.

Effects of an Extract of Salmon Milt on Symptoms and Serum TNF and Substance P in Patients With Fibromyalgia Syndrome

PURPOSE

The aim of this study was to evaluate the effects of a dietary supplement containing primarily an extract of salmon's milt (semen) on symptoms and blood levels of proinflammatory molecules in patients with fibromyalgia syndrome (FMS), a chronic, painful musculoskeletal disease without a distinct pathogenesis or treatment. We recently reported increased serum levels of the proinflammatory molecules substance P (SP) and tumor necrosis factor (TNF) in patients with FMS as compared to those in normal controls.

METHODS

This prospective, open-label study was conducted in patients with FMS (n = 87; 80 women, 7 men; age range, 18-80 years) selected from 2 clinical centers in Spain. Patients were administered the supplement and were evaluated at weeks 1 (before treatment), 4, 8, and 12 (end of treatment) for clinical parameters of functioning, fatigue, and pain, as well as overall impression. Patients were directed to take 1 capsule per day in the morning for the first 4 weeks, followed by 1 capsule in the morning and 1 capsule in the evening for the remaining 8 weeks. Differences in symptom scores in patients with FMS between weeks 1 and weeks 4, 8, and 12 were evaluated using ANOVA. Blood was obtained and serum separated in patients with FMS at 1 and 12 weeks and in a separate population of healthy controls (n = 20; 15 women, 5 men; age range, 25-65 years). Serum levels of SP and TNF were measured in patients with FMS at 1 and 12 weeks and in healthy controls by ELISA. TNF and SP levels in patients with FMS were compared between weeks 1 and 12, as well as between patients with FMS and untreated controls, using the Mann-Whitney U test.

FINDINGS

Clinical parameters of functioning, fatigue, and pain, as well as overall impression, were improved significantly at 4 weeks as compared to 1 week and remained unchanged for the duration of the study (all, P < 0.0001). Serum TNF and SP levels were significantly elevated at 1 week in patients with FMS compared to controls and were decreased significantly at 12 weeks as compared to 1 week (all, P < 0.0001).

IMPLICATIONS

Our findings indicate that this dietary supplement may significantly improve symptoms in patients with FMS. This is the first time to our knowledge that any molecule has been reported to be associated with a reduction in serum SP level. Consequently, the supplement or its hypothesized main active ingredient, spermine, may be developed as a novel treatment approach to FMS or other neuroinflammatory conditions. ClinicalTrials.gov identifier: NCT03911882.

Infiltration of T Cells into a Three-Dimensional Psoriatic Skin Model Mimics Pathological Key Features

Psoriasis is an autoimmune chronic dermatosis that is T cell-mediated, characterized by epidermal thickening, aberrant epidermal differentiation and inflammatory infiltrates, with a dominant Th1 and Th17 profile. Additional in vitro models are required to study the complex interactions between activated T cells and skin cells, and to develop new, more effective treatments. We have therefore sought to model this psoriatic inflammation by the generation of tissue-engineered immunocompetent tissues, and we have investigated the response of activated T-cell infiltration in models produced with lesional psoriatic skin cells on major hallmarks of psoriasis. The immunocompetent lesional skin model displayed a delayed onset of epidermal differentiation, an hyperproliferation of the basal keratinocytes, a drastic increase in the secretion of proinflammatory cytokines, and a disturbed expression of key transcription factors, as observed in lesional plaques, suggesting a crucial importance of combining the pathological phenotype of cutaneous cells to T cells in order to generate a relevant model for psoriasis. Finally, we found this skin model to be responsive to methotrexate treatment, making it a valuable tool for drug development.

Increased risk of migraine in patients with psoriasis: A longitudinal follow up study using a national sample cohort

Both psoriasis and migraine are associated with inflammatory diseases. However, few studies have been conducted the increased risk of migraine in psoriasis patients. The aim of this study was to identify whether the psoriasis increases the risk of migraine. This study used the national cohort study data collected by the Korean Health Insurance Review and Assessment from 2002 to 2013. Patients with psoriasis (n = 11,071) and control participants (n = 44,284) were selected and matched 1:4 by age, sex, income, region of residence, and past medical history of hypertension, diabetes, and dyslipidemia. This study used Cox-proportional hazard model for calculating hazard ratio (HR) with crude and adjusted model. Stratification by age and sex was analyzed. Migraines occurred significantly more frequently in psoriasis patients than in control participants (adjusted HR = 1.16, 95% confidence interval (CI) = 1.04-1.31, P <.05). In the stratification analysis, migraines occurred significantly more frequently in psoriasis patients than in control participants only in the group of middle-aged males (adjusted HR = 1.62 95% CI = 1.22-2.13, P = .001). In conclusion, psoriasis might increase the risk of migraine.

Potentiation of capsaicin-induced neurogenic inflammation by 5-HT7 receptors in the rat hind paw: Involvement of calcitonin gen-related peptide

A decrease in the activation threshold of primary sensory neurons to transient receptor potential V1 (TRPV1) stimulation by serotonin 5-HT7 receptors has been reported but no confirmation if this might translate into facilitation of neurogenic inflammation has been provided. We analysed the modulation of capsaicin (CAP)-induced neurogenic inflammation in the rat hind paw by the selective 5-HT7 receptor agonist, LP-44, and the involvement of calcitonin gen-related peptide (CGRP) in this effect. Animals received intra-plantar injections (30 μL) of vehicle, CAP (0.05%, 0.1% and 0.2%), LP-44 (7.5 and 15 nmol) and the combination of LP-44 + CAP; then, the time course of the inflammatory responses was measured. The effect of the 5-HT7 receptor antagonist, SB-269970 (3 mg/kg, s.c.), on responses produced by LP-44 alone and combined with CAP was tested. As expected, CAP produced concentration- and time-dependent inflammatory responses in the hind paw. Interestingly, LP-44 by itself also produced inflammation in a concentration- and time-dependent manner, and magnified CAP-induced responses. Systemic pre-treatment with SB-269970 significantly blunted LP-44 (15 nmol)-induced inflammation as well as magnified inflammatory responses produced by the combination of LP-44 (7.5 and 15 nmol) + CAP (0.1%) thus confirming the involvement of 5-HT7 receptors. Finally, the non-peptide CGRP receptor antagonist, BIBN4096 (3 mg/kg, s.c.), strongly inhibited the potentiated inflammatory responses induced by LP-44 (7.5 and 15 nmol) + CAP (0.1%) thus substantiating their neurogenic nature. Thus, sensitization of CAP-sensitive primary sensory neurons by 5-HT7 receptors may result in facilitation of neurogenic inflammation involving CGRP in the rat hind paw.

Skin neurogenic inflammation

The epidermis closely interacts with nerve endings, and both epidermis and nerves produce substances for mutual sustenance. Neuropeptides, like substance P (SP) and calcitonin gene-related protein (CGRP), are produced by sensory nerves in the dermis; they induce mast cells to release vasoactive amines that facilitate infiltration of neutrophils and T cells. Some receptors are more important than others in the generation of itch. The Mas-related G protein-coupled receptors (Mrgpr) family as well as transient receptor potential ankyrin 1 (TRPA1) and protease activated receptor 2(Par2) have important roles in itch and inflammation. The activation of MrgprX1 degranulates mast cells to communicate with sensory nerve and cutaneous cells for developing neurogenic inflammation. Mrgprs and transient receptor potential vanilloid 4 (TRPV4) are crucial for the generation of skin diseases like rosacea, while SP, CGRP, somatostatin, β-endorphin, vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating polypeptide (PACAP) can modulate the immune system during psoriasis development. The increased level of SP, in atopic dermatitis, induces the release of interferon (IFN)-γ, interleukin (IL)-4, tumor necrosis factor (TNF)-α, and IL-10 from the peripheral blood mononuclear leukocytes. We are finally starting to understand the intricate connections between the skin neurons and resident skin cells and how their interaction can be key to controlling inflammation and from there the pathogenesis of diseases like atopic dermatitis, psoriasis, and rosacea.

The associations between psychological stress and psoriasis: a systematic review

Psoriasis is estimated to affect around 2-3% of the general population. More than one-third of Australians report having a significant level of distress in their daily lives. Psychological stress has long been shown to play an important role in the natural history of psoriasis, but the details of this relationship remain to be clearly defined. We performed a systematic review of the literature with the aim of determining whether there is a temporal association between psychological stress as the predictor and onset and/or exacerbation of psoriasis as the outcome measure. Our secondary aim was to establish whether there is a relationship between the degree of psychological stress and clinical severity of psoriasis. Our systematic review demonstrates a probable temporal association between different measures of psychological stress and onset, recurrence, and severity of psoriasis. In the light of this, we suggest clinicians include "stress" as a trigger factor in their psoriasis assessment and consider psychological interventions as adjuncts, particularly in those who identify as "stress-responders".

Interleukin 33 and interleukin 4 regulate interleukin 31 gene expression and secretion from human laboratory of allergic diseases 2 mast cells stimulated by substance P and/or immunoglobulin E

BACKGROUND

Cytokine interleukin (IL) 31 has emerged as an important component of allergic and inflammatory diseases associated with pruritus, such as atopic dermatitis (AD) and mastocytosis. Mast cells (MC) are stimulated by allergic and nonallergic triggers, and play a critical role in such diseases by secreting histamine and tryptase as well as cytokines and chemokines. IL-33 has been reported to augment MC responses, but its effect on secretion of IL-31 is not known.

OBJECTIVES

To investigate whether IL-33 can stimulate the secretion of IL-31 from cultured human MCs and whether this response is augmented by either the neuropeptide substance P (SP) or immunoglobulin E (IgE) and anti-IgE in the absence or presence of IL-4.

METHODS

Laboratory of Allergic Diseases (LAD2) human MCs were cultured in StemProH-34 SFM medium supplemented by stem cell factor and were stimulated either with IL-33 (10 ng /mL) or SP (2 μM), or preincubated with IgE (1 μg/mL) overnight, and then stimulated with anti-IgE (1 μg/mL) for 24 hours. IL-31 gene expression was measured by quantitative polymerase chain reaction, and protein was measured by enzyme-linked immunosorbent assay.

RESULTS

IL-33 (10 ng/mL) induces IL-31 gene expression, synthesis, and secretion from LAD2 cells in the absence of degranulation, whereas SP and IgE on their own have no effect. However, the effect of IL-33 is augmented by SP (2 μM) and/or IgE and anti-IgE (1 μg/mL both) and especially their combination. Moreover, this response is significantly further increased when LAD2 cells are cultured in the presence of IL-4.

CONCLUSION

These findings provide evidence that IL-33 induced secretion of IL-31 from LAD2 MC, an action augmented by novel neuroimmune interactions that may help in the development of new treatments of allergic and inflammatory diseases, especially AD and mastocytosis.

Chronic social stress Ameliorates psoriasiform dermatitis through upregulation of the Hypothalamic-Pituitary-Adrenal axis

Acute stress is a physiological response of an organism to adverse conditions, contributing to survival; however, persistence through time may lead to disease. Indeed, exacerbation of inflammatory conditions such as psoriasis has been reported to follow stressors in susceptible patients. Because chronic stress cannot ethically be elicited in patients under controlled laboratory conditions, we studied genetically modified mice that naturally develop psoriasiform dermatitis, and subjected them to an ethological chronic social contact stress paradigm. Although we found elevated pro-inflammatory neuropeptide production of substance P (SP), calcitonin-gene-related peptide (CGRP) and nerve-growth factor (NGF) mRNA in the dorsal root ganglia (DRG) as well as pro-inflammatory cytokines in response to the social stressor, stress paradoxically prevented the development of the skin lesions. This effect of stress could be reversed by the treatment with glucocorticoid (GC) receptor blockers, suggesting that it was mediated through the upregulation of corticosterone secretion. Extrapolating to humans, the worsening of disease in susceptible patients with psoriasis could be attributed to a defect in the Hypothalamic-Pituitary-Adrenal (HPA) axis with an impaired production of GC during situations of adversity, thus rendering them unable to counteract the pro-inflammatory effects of chronic stressors.

Anti-interleukin and interleukin therapies for psoriasis: current evidence and clinical usefulness

Anti-interleukin (IL) therapies have emerged as a major treatment for patients with moderate-to-severe psoriasis. This article reviews the up-to-date results of pivotal clinical trials targeting the interleukins used for the treatment of psoriasis, including IL-1, IL-2, IL-6, IL-8, IL-10, IL-12, IL-17, IL-20, IL-22, IL-23, IL-36 and bispecific biologics IL-17A/tumor necrosis factor alpha (TNF-α). Cytokines involved in the circuits of psoriasis inflammation without ongoing clinical trials are also mentioned (IL-9, IL-13, IL-15, IL-16, IL-18, IL-19, IL-21, IL-24, IL-27, IL-33, IL-35, IL-37, and IL-38).

Modulation of CD4+ T Helper Cell Memory Responses in the Human Skin

Immunological memory is defined as the capacity to mount faster and more effective immune responses against antigenic challenges that have been previously encountered by the host. CD4+ T helper (Th) cells play central roles in the establishment of immunological memory as they assist the functions of other leukocytes. Th cells express polarized cytokine profiles and distinct migratory and seeding capacities, but also retain a certain functional plasticity that allows them to modulate their proliferation, activity, and homing behaviour upon need. Thus, in healthy individuals, T cell immunomodulation fulfils the task of eliciting protective immune responses where they are needed. At times, however, Th plasticity can lead to collateral tissue damage and progression to autoimmune diseases or, conversely, incapacity to reject malignant tissues and clear chronic infections. Furthermore, common immune players and molecular pathways of diseases can lead to different outcomes in different individuals. A mechanistic understanding of those pathways is therefore crucial for developing precise and curative medical interventions. Here, I focus on the skin microenvironment and comprehensively describe some of the cellular and molecular determinants of CD4+ T cell memory responses in homeostatic and pathological conditions. In discussing the cellular network orchestrating cutaneous immunity, I comprehensively describe the bidirectional interaction of skin antigen-presenting cells and mononuclear phagocytes with Th17 lymphocytes, and examine how the outcome of this interaction is influenced by endogenous skin molecules, including sodium salts and neuropeptides.

Innervation of the Male Breast: Psychological and Physiological Consequences

Breasts, including the nipple and areola, have two functions: lactation and as an erogenous area. Male breasts are much less studied that those of women. In men, breasts have only an erotic function. Because there is dense and very well organized innervation of the nipple-areola complex in men, nipple erection occurs frequently and via different mechanisms from penile erection. Although it seems to be less important for men than for women and it is poorly studied, the erotic value of breast stimulation is notable. Consequently, there is a need to include this aspect in sexological and andrological studies and to preserve breasts and their innervation or to reconstruct them in cases of surgical intervention.

SP and IL-33 together markedly enhance TNF synthesis and secretion from human mast cells mediated by the interaction of their receptors

The peptide substance P (SP) and the cytokine tumor necrosis factor (TNF) have been implicated in inflammatory processes. Mast cells are recognized as important in inflammatory responses. Here, we report that IL-33 (30 ng/mL), a member of the IL-1 family of cytokines, administered in combination with SP (1 µM), markedly increase (by 1,000-fold) TNF gene expression in cultured human LAD2 and primary mast cells derived from umbilical cord blood. SP (0.01-1 μM) and IL-33 (1-100 ng/mL) in combination also greatly stimulate TNF secretion (by 4,500-fold). Pretreatment of LAD2 cells with two different neurokinin-1 (NK-1) receptor antagonists and siRNA inhibits TNF secretion by 50% (P < 0.001) when stimulated by SP and IL-33. Pretreatment of LAD2 cells with a neutralizing antibody for IL-33 receptor, ST2, inhibits TNF secretion by 50% (P < 0.001), and ST2 siRNA decreases TNF secretion by 30% (P < 0.05), when stimulated by SP and IL-33. Surprisingly, NK-1 antagonists also inhibit 50% of TNF secretion (P < 0.001) when stimulated only by IL-33, and ST2 receptor reduction also decreases SP-stimulated TNF secretion by 30% (P < 0.05), suggesting an interaction between NK-1 and ST2 receptors. Moreover, IL-33 increases NK-1 gene and surface protein expression, as well as IKβ-α phosphorylation. Pretreatment of LAD2 cells with 5,7,3',4'-tetramethoxyflavone (methoxyluteolin) (1-100 μM) inhibits (P < 0.001) TNF gene expression (98%) and secretion (64%) at 50 µM and phosphorylation of p-IKB-α at 1 μM when stimulated by SP and IL-33. These findings identify a unique amplification process of TNF synthesis and secretion via the interaction of NK-1 and ST2 receptors inhibitable by methoxyluteolin.

Surgical Denervation in the Imiquimod-Induced Psoriasiform Mouse Model

Psoriasis is a chronic inflammatory skin disease with a prevalence of 2-3 %. It appears to result from a combination of genetic and environmental factors, but the precise pathogenesis is still unknown. Neurogenic inflammation is involved in psoriasis pathogenesis as well, but the role of neurogenic factors is currently unclear. Molecular studies often involve material obtained from patients. However, many questions and especially experimental manipulations are not suited for study in humans. Imiquimod application on mouse skin leads to immune cell infiltration, inflammation with intense redness, epidermal thickening, and scaling that jointly greatly resembles human psoriasis. Here we describe the use of surgical denervation in the imiquimod-induced psoriasiform model, to study the role of skin innervation and neuropeptides in the pathogenesis of psoriasis.