Phototherapy reduces the number of epidermal and CGRP-positive dermal nerve fibres

Exosomes: A Promising Cell-Free Therapeutic Tool for Treating Cutaneous Nerve Injuries and Promoting Wound Healing

The skin is the body's largest organ. It serves various functions, including protection and metabolism. Due to its structure and location, it is more vulnerable to external physical and chemical damage than internal organs. Additionally, certain endogenous diseases can cause pathological changes to appear on the skin and nerves. When skin tissue breaks down or sustains severe trauma, the cells, blood vessels, and nerves across all layers can suffer varying degrees of damage. This often results in pain, itching, sensory disturbances, and other discomforts, causing significant distress to patients. Stem-cell-derived exosome therapy has emerged as a promising treatment for skin injuries due to its safety, non-toxicity, and precision medicine benefits. Research has shown that stem-cell-derived exosomes regulate nerve cells by mediating MicroRNA (miRNA) transport and expression between cells, promoting axon growth. This exosome-driven miRNA exchange serves as a vital mode of intercellular communication, playing a crucial role in nervous system repair. Nerves play a critical role in skin wound healing and tissue regeneration, with sensory and autonomic nerves influencing key skin functions such as inflammation, immune defense, apoptosis, proliferation, and wound repair. Exosomes may aid in treating cutaneous nerve injuries by directly or indirectly promoting axon regeneration, nerve cell proliferation, and the release of protective neurofactors.

Gabapentin versus narrowband ultraviolet B phototherapy versus combination of both in treatment of uremic pruritus

BACKGROUND

Pruritus is a common skin symptom manifesting with an unpleasant sensation and desire to itch and scratch. Pruritis can be a hallmark of many skin diseases as well as other non cuatneous diseases.

AIM OF THE STUDY

To compare the efficacy of gabapentin versus narrow band UVB versus combination of both in treatment of uremic pruritus.

METHODS

This study that included 60 patients diagnosed with uremic pruritus, randomly allocated into one of three groups. Group A received oral gabapentin 300 mg OD for six weeks, group B received NB-UVB phototherapy three times per week in nonconsecutive days for a total of 18 sessions (6 weeks) and group C received combination of both therapies for 6 weeks. Efficacy was assessed by visual analogue scale (VAS) and 5-D itch scale before and after the end of therapy.

RESULTS

Significant difference of VAS score between groups A & C (P = 0.029) and between group B & C (P = 0.027) was demonstrated. Complete responders represented 55% of group C (combination treatment group), 20% of group A & only 15% of group B. The highest frequency of no response was detected for group A (30%) followed by group B (15%) and lowest for group C (5%).

CONCLUSION

Combination of both gabapentin and NB-UVB is a promising medication for the treatment of uremic pruritus. Further well-designed clinical and experimental studies are needed to clarify the relationship between the frequency of NB-UVB phototherapy sessions and gabapentin dosing for an optimal response.

Efficacy and safety of narrowband ultraviolet B phototherapy for prurigo nodularis: a tertiary center experience

BACKGROUND

Prurigo nodularis is a chronic pruritic dermatosis and narrowband-UVB (NB-UVB) phototherapy is considered an effective and safe treatment option in patients with multiple comorbidities.

OBJECTIVE

In this study, the authors aimed to evaluate the efficacy and safety of NB-UVB phototherapy in the management of prurigo nodularis and to compare response rates according to lesions localization.

METHODS

Thirty prurigo nodularis patients who had been treated with NB-UVB phototherapy were included in this study. The data for this study were retrieved retrospectively from patient follow-up forms in the phototherapy unit.

RESULTS

NB-UVB phototherapy led to a complete response (CR) in 24 (80%) patients while partial response (PR) was achieved in 6 (20%) patients. Regarding prurigo nodularis localization, the CR rate was statistically higher in those with diffuse and central involvement (p < 0.05). Erythema and/or pruritus were observed in 4 (13.3%) patients with prurigo nodularis.

STUDY LIMITATIONS

This study is limited because it is single-centered and has a retrospective design.

CONCLUSIONS

NB-UVB phototherapy is an effective and safe treatment option for prurigo nodularis patients especially those with multiple comorbidities and using several medications. Patients with diffuse and central involvement may respond better to phototherapy than those with peripheral involvement.

Excimer light effect on neurogenic inflammation in active versus stable psoriasis lesions

Neurogenic inflammation, mediated by T helper 17 cell (Th17) and neurons that release neuropeptides such as substance P (SP), is thought to play a role in the pathogenesis of psoriasis. Excimer light is used in the treatment of psoriasis via induction of T cell apoptosis. The objective of this study is to study the effect of excimer light on active versus stable psoriasis and investigate the levels of substance P and its receptor in both groups. The study included 27 stable and 27 active psoriatic patients as well as 10 matched healthy controls. Clinical examination (in the form of local psoriasis severity index (PSI) and visual analogue scale (VAS)) was done to determine disease severity, level of itching, and quality of life. Tissue levels of SP and neurokinin-1 receptor (NK-1R) were measured by ELISA before and after 9 excimer light sessions in 43 patients. A statistically significant lower levels of PSI and VAS were reached after therapy with no significant difference between the stable and active groups. The mean tissue levels of SP before therapy were significantly higher than the control group. Lower levels of SP and NK-1 receptor were found after treatment overall and in each group. Excimer therapy can be effective for both stable and active plaque psoriasis and this effect could be partly through its role on ameliorating the neurogenic inflammation.

The impact of phototherapy on itch intensity and itch-related quality of life amongst different skin diseases, skin phototypes and genders - A prospective study with 102 patients

BACKGROUND

Phototherapy is a mainstay to treat itchy conditions. However, only little is known about differences in the antipruritic effect of phototherapy amongst different skin conditions, phototypes and genders.

METHODS

In this prospective, single-center study, we analyzed the effect of phototherapy on itch intensity and itch-related quality of life amongst these subgroups after a treatment duration of 4 weeks, while on-demand treatment with topical corticosteroids, topical calcineurin inhibitors and/or antihistamines was allowed.

RESULTS

Of 102 patients (age 53.0 ± 18.7, 56 females [54.9%]), 72 (78.3%) reported a significant reduction of itch intensity by Δ -2.76 on a 0-10 Numerical Rating Scale (NRS), p = <.001, 95% CI [2.2; 3.3] paralleled by a significant improvement of itch-related quality of life as measured by the German version of the ItchyQoL by Δ 7.3, p = <.001, 95% CI [4.4; 11.6]. The best improvement of itch intensity and itch-related QoL was reported by patients with pruritus on non-diseased skin (ΔNRS -3.5; Δ 9.7 Ger-ItchyQoL points), followed by patients with atopic dermatitis and psoriasis. We found no statistical differences in the response to phototherapy amongst Fitzpatrick phototypes I-VI. Women had higher itch intensities at baseline but itch-related quality of life impairment at baseline and phototherapy treatment response did not significantly differ between genders.

CONCLUSION

Phototherapy appears to induce a meaningful itch reduction in various itchy skin conditions, all phototypes and both genders within 4 weeks that directly translates into improvement of itch-related quality of life.

When topical therapy of atopic dermatitis fails: a guide for the clinician

INTRODUCTION

While topical medications are the first line of treatment for mild-to-moderate atopic dermatitis, they are ineffective in individuals with diffuse disease and moderate-to-severe atopic itch. For these individuals, as well as those who do not respond to topical treatments, systemic medicines are typically essential and helpful.

AREAS COVERED

We conducted a review of the literature to identify established systemic therapies, novel biologic agents, and recent advances in the pathophysiology of atopic dermatitis. The review discusses these data, which show that the majority of atopic itch medications now in development target the type 2 immune axis and brain sensitization, two main etiologies of atopic itch. We emphasize the evidence, efficacy, and side effect profiles of currently available systemic medications for atopic itch, as well as future potential for tailored therapy.

EXPERT OPINION

We give our professional opinion on the current state of knowledge about atopic eczema pathogenesis and the innovative targets and therapies for atopic itch that include MRGPRX2, periostin, gabaergic medicines, and JAK/STAT inhibitors. Additionally, we discuss patient populations that stand to benefit the most from targeting these molecules or utilizing these drugs, as well as those who may face a disproportionate weight of adverse effects.

Neurophysiological assessment of brachioradial pruritus patients

BACKGROUND

Pruritus is a common complaint in dermatology. Wartenberg, in 1943, associated pruritus with neuropathy, relating it to the "posterior antebrachial cutaneous nerve neuropathy". In 1968, Waisman described patients with frequent pruritus complaints in the upper limb during the summer, which he named "brachioradial summer pruritus". Currently, this pruritus is named brachioradial pruritus (BRP). BRP is characterized by a chronic pruritus, usually localized, with a long duration, and without apparent cutaneous abnormalities. Neurological disorders both from the central and peripheral nervous systems, including multiple sclerosis, are associated with pruritus.

OBJECTIVE

To investigate correlations between symptomatic dermatomes and alterations in the myotomes, as evidenced by electroneuromyography (ENMG).

METHODS

Forty-six patients with BRP dermatological diagnoses were subjected to upper limb ENMG.

RESULTS

Among 46 patients with C5 to C8 dermatomal pruritus, we evaluated 113 symptomatic dermatomal areas. Overall, 39 (85%) patients had radicular involvement and 28 (60%) had agreement between complaint and the ENMG findings (p=0.015). A total of 80% of the patients with complaints at C7 and 47% at C6 had radicular involvement at the same level.

CONCLUSIONS

Among the patients who presented complaints, 47 and 80%, respectively, had ENMG alterations in the C6 and C7 myotomes. We conclude that peripheral nervous system involvement is associated with BRP.

Current Clinical Options for the Management of Itch in Atopic Dermatitis

Pruritus is the most burdensome and prevalent symptom in patients suffering from atopic dermatitis. Treating atopic itch has historically been a challenge due to multiple underlying mechanisms within its pathogenesis and an incomplete understanding of them. In recent years, our understanding of these mechanisms have increased tremendously and subsequently, new treatments have reached the market that target the pathophysiology of atopic itch from different angles. In addition, there are several promising new treatments currently in development and trials. In the current article, we discuss these currently available treatment options, their available evidence and efficacy, and highlight some of the more recent advancements in the field.

Neuropeptides and neurohormones in immune, inflammatory and cellular responses to ultraviolet radiation

Humans are exposed to varying amounts of ultraviolet radiation (UVR) through sunlight. UVR penetrates into human skin leading to release of neuropeptides, neurotransmitters and neuroendocrine hormones. These messengers released from local sensory nerves, keratinocytes, Langerhans cells (LCs), mast cells, melanocytes and endothelial cells (ECs) modulate local and systemic immune responses, mediate inflammation and promote differing cell biologic effects. In this review, we will focus on both animal and human studies that elucidate the roles of calcitonin gene-related peptide (CGRP), substance P (SP), nerve growth factor (NGF), nitric oxide and proopiomelanocortin (POMC) derivatives in mediating immune and inflammatory effects of exposure to UVR as well as other cell biologic effects of UVR exposure.

Intractable Itch in Atopic Dermatitis: Causes and Treatments

Itch or pruritus is the hallmark of atopic dermatitis and is defined as an unpleasant sensation that evokes the desire to scratch. It is also believed that itch is a signal of danger from various environmental factors or physiological abnormalities. Because histamine is a well-known substance inducing itch, H₁-antihistamines are the most frequently used drugs to treat pruritus. However, H₁-antihistamines are not fully effective against intractable itch in patients with atopic dermatitis. Given that intractable itch is a clinical problem that markedly decreases quality of life, its treatment in atopic dermatitis is of high importance. Histamine-independent itch may be elicited by various pruritogens, including proteases, cytokines, neuropeptides, lipids, and opioids, and their cognate receptors, such as protease-activated receptors, cytokine receptors, Mas-related G protein-coupled receptors, opioid receptors, and transient receptor potential channels. In addition, cutaneous hyperinnervation is partly involved in itch sensitization in the periphery. It is believed that dry skin is a key feature of intractable itch in atopic dermatitis. Treatment of the underlying conditions that cause itch is necessary to improve the quality of life of patients with atopic dermatitis. This review describes current insights into the pathophysiology of itch and its treatment in atopic dermatitis.

Pathophysiology, diagnosis, and pharmacological treatment of prurigo nodularis

Introduction: Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by intensely pruritic, hyperkeratotic nodules distributed on the trunk and extensor surfaces of the extremities. PN has a profoundly negative impact on sleep and quality of life in patients with PN. There are currently no U.S. Food and Drug Administration-approved agents and patients are often recalcitrant to current therapies, highlighting the importance of further research into this severely debilitating condition. Areas covered: A PubMed search was conducted to find available literature on the pathophysiology and clinical management of PN. In this review article, we discuss the current understanding of the pathophysiology, recommended diagnostic approach, and treatment options available for PN. Expert opinion/commentary: PN is an extremely difficult condition to treat, because there is a lack of effective therapies available due to our limited understanding of its pathophysiology. Currently, available treatment options are often multimodal due to the intersection of neuroimmune etiologic factors in the pathogenesis of PN. Fortunately, as our knowledge of PN expands, novel treatments targeting specific molecular biomarkers of PN are emerging, providing hope to this long-suffering patient population.

Characterization of dermal skin innervation in fibromyalgia syndrome

Introduction

We characterized dermal innervation in patients with fibromyalgia syndrome (FMS) as potential contribution to small fiber pathology.

Methods

Skin biopsies of the calf were collected (86 FMS patients, 35 healthy controls). Skin was immunoreacted with antibodies against protein gene product 9.5, calcitonine gene-related peptide, substance P, CD31, and neurofilament 200 for small fiber subtypes. We assessed two skin sections per patient; on each skin section, two dermal areas (150 x 700 μm each) were investigated for dermal nerve fiber length (DNFL).

Results

In FMS patients we found reduced DNFL of fibers with vessel contact compared to healthy controls (p<0.05). There were no differences for the other nerve fiber subtypes.

Discussion

We found less dermal nerve fibers in contact with blood vessels in FMS patients than in controls. The pathophysiological relevance of this finding is unclear, but we suggest the possibility of a relationship with impaired thermal tolerance commonly reported by FMS patients.

Is there still a role for UV therapy in itch treatment?

Itching is a frequent and greatly distressing symptom related to many skin and systemic diseases. New insights into the pathophysiology of itchy skin and potentially involved mediators have increased the interest in and development of new treatments that specifically act on targets involved in the transmission and perception of itching. Phototherapy has long been known and used as an effective treatment for various kinds of chronic itching. However, despite its well-known beneficial effects, the mechanisms behind the antipruritic effect of phototherapy are less well-known. In addition, phototherapy requires the use of expensive equipment in dermatology offices, patients must undergo repeated treatments and no large, randomized, controlled trials have yet supported the antipruritic effect of UV. Therefore, phototherapy is rarely recommended as a treatment method for chronic pruritic diseases or only used as a last recourse. However, the wide range of pruritic conditions that can be successfully treated with phototherapy, together with its low acute side effects, extremely low frequency of interactions with other medications, possibilities to combine phototherapy with other treatment modalities and the fact that patients of almost all ages-from childhood to old age, including women during pregnancy or lactation-can be treated make UV therapy advantageous over other treatments of chronic pruritus. Thus, despite the development of new targeted therapies against pruritus, UV therapy is neither outdated nor the 'last recourse', but should be considered early on in the treatment of chronic pruritus.

Treatment-resistant prurigo nodularis: challenges and solutions

Prurigo nodualris (PN) is a chronic condition with highly pruritic, hyperkeratotic papules or nodules arising in the setting of chronic pruritus. While PN may serve as a phenotypic presentation of several underlying conditions such as atopic dermatitis, chronic kidney disease-related pruritus, and neurological diseases, it represents a distinct clinical entity that may persist despite the removal of the underlying cause, if one is identified. Neuronal proliferation, eosinophils, mast cells, and small-fiber neuropathy play a role in the production of pruritus in PN, although the exact mechanism has not yet been established. Identifying an underlying cause, if present, is essential to prevent recurrence of PN. Due to often present comorbidities, treatment is typically multimodal with utilization of topical and systemic therapies. We performed a PubMed/MEDLINE search for PN and present a review of recent developments in the treatment of PN. Treatment typically relies on the use of topical or intralesional steroids, though more severe or recalcitrant cases often necessitate the use of phototherapy or systemic immunosuppressives. Thalidomide and lenalidomide can both be used in severe cases; however, their toxicity profile makes them less favorable. Opioid receptor antagonists and neurokinin-1 receptor antagonists represent two novel families of therapeutic agents which may effectively treat PN with a lower toxicity profile than thalidomide or lenalidomide.

The Antipruritic Effect of Phototherapy

Phototherapy is widely used to treat inflammatory skin diseases such as psoriasis and atopic dermatitis. Repeated suberythemogenic doses of UV-light reduce inflammation in these diseases and ultimately may lead to a complete disappearance of cutaneous symptoms for weeks or months. Chronic pruritus is an important and highly distressing symptom of many of these inflammatory skin diseases. Interestingly, pruritus is also reduced or completely abolished by UV-treatment of psoriasis and atopic dermatitis, and sometimes reduction of pruritus is the first indication for skin improvement by phototherapy. The cutaneous nervous system is an integral part of skin anatomy, and free nerve endings of sensory cutaneous nerve fibers reach up into the epidermis getting in close contact with epidermal cells and mediators from epidermal cells released into the intercellular space. Stimulation of “pruriceptors” within this group of sensory nerve fibers generates a neuronal signal eventually transmitted via the dorsal root and the spinal cord to the brain, where it is recognized as “itch”. UV-light may directly affect cutaneous sensory nerve fibers or, via the release of mediators from cells within the skin, indirectly modulate their function as well as the transmission of itch to the central nervous system inducing the clinically recognized antipruritic effect of phototherapy.

A systematic review of evidence-based treatments for prurigo nodularis

Prurigo nodularis is a chronic dermatologic condition involving the development of multiple cutaneous nodules in the setting of intractable pruritus. Given emerging treatment options for this difficult-to-treat condition, a current review of therapeutics is needed. A systematic review was performed for clinical studies investigating prurigo nodularis treatment published from 1990 to present including ≥5 subjects. A total of 35 articles were assigned a level of evidence according to the Oxford Center for Evidence-based Medicine. All 5 studies investigating topical agents, including corticosteroids, calcineurin inhibitors, calcipotriol, and capsaicin, conveyed some beneficial effect with level of evidence 2b or higher. Six of 8 reports investigating photo- and photochemotherapy achieved levels of evidence 2b or greater and showed good partial response rates. Thalidomide was studied by 6 reports providing evidence of good symptom response, only 2 of which were rated level 2b or greater. Cyclosporine and methotrexate have demonstrated benefit in 4 combined studies, albeit with level 4 evidence. Pregabalin, amitriptyline, paroxetine, fluvoxamine, and neurokinin-1 receptor antagonists have demonstrated promising evidence in 5 level 2b studies. Higher-powered studies and additional randomized controlled trials are needed for the evaluation of safe and efficacious systemic treatment options for prurigo nodularis.

Management of Itch in Atopic Dermatitis

Atopic dermatitis (AD) is the most common itchy dermatosis that affects millions of children and adults worldwide. Chronic itch in this condition has significant impact on measures of quality of life, such as sleep. Treating itch in AD has been challenging for decades, but new drugs have emerged in the last year with significant anti-pruritic effect. The optimal treatment regimen for atopic itch addresses barrier dysfunction, inflammation, neural hypersensitivity, and the itch-scratch cycle. Topical moisturizers remain the foundation of treatment and should be used by all patients with AD-associated pruritus. Step-wise therapy, from topical anti-inflammatory creams to systemic monoclonal antibodies and immunosuppressants, is recommended. There are multiple adjuvant therapies that can be used, especially to target itch in the setting of minimal skin inflammation. Finally, patient education, sleep management, and stress relief are important components to optimize outcomes. This review assesses the latest advances and treatment recommendations for pruritus in AD. Finally, suggested therapeutic ladders and emerging treatments are discussed.

Lgr6+ stem cells and their progeny in mouse epidermis under regimens of exogenous skin carcinogenesis, and their absence in ensuing skin tumors

Lgr6+ cells have been identified as a novel class of proliferating (Ki67+) stem cells in mouse epidermis. We investigated their response to UV exposure in Lgr6-EGFP-Ires-CreERT2/R26R-LacZ haired and hairless mice and whether they become initiating cells of UV- or chemically induced skin tumors. UV overexposure erased Lgr6+ cells (EGFP+) from the interfollicular epidermis (IFE), but - as after wounding - they apparently repopulated the IFE from the hair follicles. Under sub-sunburn chronic UV exposure, Lgr6+ cells and their progeny (LacZ+ after pulse of tamoxifen) diminished strongly in the IFE. Although the inter-tumoral IFE clearly showed Lgr6 progeny, none of the UV- or chemically induced tumors (n = 22 and 41, respectively) appeared to be clonal expansions of Lgr6+ stem cells; i.e. no Lgr6+ cells or progeny in the proliferating tumor bulk. In checking for promoter methylation we found it to occur stochastically for the EGFP-Cre cassette. Lgr6 mRNA measured by qPCR was found to be diminished in skin tumors (also in UV tumors from wt type mice). The ratio of Lgr6/Ki67 was significantly reduced, pointing at a loss of Lgr6+ cells from the proliferative pool. Our data show that Lgr6+ cells are not major tumor-initiating cells in skin carcinogenesis.

Adjunctive Management of Itch in Atopic Dermatitis

Itch, or pruritus, is a hallmark feature of atopic dermatitis (AD). The impact of AD-related pruritus can range from mildly distressing or distracting to completely disabling. Traditionally, management of itch in AD patients has focused on restoring the altered skin barrier with topical emollients and/or reducing inflammation. A growing emphasis has been placed on directly targeting the neural transmission pathways that mediate itch signaling. Off-label use of neuromodulatory agents has helped reduce this aggravating symptom in atopic patients. This article reviews the current literature on the use of neuromodulatory agents and nonpharmacologic alternative therapies used to treat AD-related pruritus.

Atopic dermatitis: allergic dermatitis or neuroimmune dermatitis?

Advances in knowledge of neurocellulars relations have provided new directions in the understanding and treatment of numerous conditions, including atopic dermatitis. It is known that emotional, physical, chemical or biological stimuli can generate more accentuated responses in atopic patients than in non-atopic individuals; however, the complex network of control covered by these influences, especially by neuropeptides and neurotrophins, and their genetic relations, still keep secrets to be revealed. Itching and airway hyperresponsiveness, the main aspects of atopy, are associated with disruption of the neurosensory network activity. Increased epidermal innervation and production of neurotrophins, neuropeptides, cytokines and proteases, in addition to their relations with the sensory receptors in an epidermis with poor lipid mantle, are the aspects currently covered for understanding atopic dermatitis.

Progression of itching intensity and expression of growth factor proteins in skin of people suffering from atopic dermatitis under the influence of ultraviolet phototherapy

Study of progression of itching intensity and expression of growth factor proteins in skin of people suffering from atopic dermatitis under the influence of narrowband (311Nm) phototherapy. Material and methods. 30 patients with atopic dermatitis were treated by using narrowband (311Nm) phototherapy. SCORAD index was used to assess the severity of the clinical responses. Itching intensity was assessed using visual analogue scale. Expression of growth factor of nerves, semaphorine-3A, amphiregulin, and PGP9.5, a protein marker for nerve fibers, was investigated by means of indirect immunofluorescence. Results. Increased expression level of nerves growth factor, decreased expression level of semaphorine-3A, and increase in the number, average length and luminous intensity of PGP9.5+ -nerve fibers were found in the patients’ epidermis. Course of narrowband (311 Nm) phototherapy resulted in a decrease of the severity of the disease and itching intensity, and semaphorine-3A expression increase, reduction of number and average length of nerve fibers in the epidermis. A direct correlation relationship between the itching intensity and expression level of nerve growth factor, number and average length of PGP9.5+ -nerve fibers in the epidermis as well as an inverse correlation relationship between itching intensity and expression level of semaphorine-3A in the epidermis were found. Conclusion. Treating patients suffering from atopic dermatitis with narrowband (311 Nm) phototherapy leads to a decrease of the itching intensity associated with a decreased intensity of innervation of the epidermis. This decrease in course of phototherapy is facilitated by decrease of nerve growth factor expression level and increase of semaphorine-3A expression.

Dynamics of expression rates of growth factor proteins in psoriatic patients receiving a phototherapy

Goal. To study the dynamics of expression rates of growth factor proteins in psoriatic patients receiving the PUVA therapy. Materials and methods. The authors conducted a study of 30 patients with psoriasis vulgaris treated with the PUVA therapy. The psoriasis severity and extent of itching were assessed prior to and after the treatment by the PASI index and visual analogue scale, respectively. The expression of semaphorin 3A, amphiregulin, nerve growth factor and PGP 9.5 protein (a nerve fiber marker) in the skin was assessed by the indirect immunofluorescence method. The expression of PGP 9.5 protein was used to assess the quantity and mean length as well as average and total fluorescence intensity of nerve fibers. Results. An increased expression of amphiregulin and nerve growth factor as well as increase in the quantity, mean length and average and total fluorescence intensity of nerve fibers were revealed in the epidermis of psoriatic patients. Following a course of the PUVA therapy, a decrease in the PASI index and extent of itching, reduced expression of amphiregulin and nerve growth factor as well as reduced quantity, mean length and average and total fluorescence intensity of nerve fibers in the epidermis were observed. Direct correlation dependence between the extent of itching, amphiregulin and nerve growth factor expression level and quantity and length of nerve fibers in the epidermis was discovered. Direct correlation dependence between the amphiregulin and nerve growth factor expression level, and average length of nerve fibers in the epidermis was discovered. Conclusion. The itching intensity in psoriatic patients receiving the PUVA therapy is reduced due to the decreased skin expression of the nerve growth factor and amphiregulin.

PGP 9.5 distribution patterns in biopsies from early lesions of atopic dermatitis

Peripheral nerve fibres are often increased in lesional skin of atopic dermatitis (AD) patients. We attempted to study nerve fibre profiles, using PGP 9.5 as neuronal marker, in early AD lesions in 10 patients, as compared to non-lesional skin in the same patients and skin from healthy controls. The number of PGP 9.5-positive nerve fibre profiles was not different in the biopsies taken from normal-looking AD skin and healthy controls. The total number of PGP 9.5-positive nerve fibre profiles in the whole skin sections was higher in both the epidermis and the dermis in the group of skin biopsies taken from early lesions of AD patients. Further, the number of epidermal PGP 9.5-positive dendritic cells was increased in AD skin. It seems reasonable that PGP 9.5-positive nerve fibres and PGP 9.5-positive dendritic cells have pathological roles in AD. The findings might serve as a basis for further studies in evaluating novel diagnostic and therapeutic approaches.

Changes in hind paw epidermal thickness, peripheral nerve distribution and mechanical sensitivity after immobilization in rats

This study was designed to investigate histological changes in skin tissue accompanying immobilization-induced hypersensitivity. Changes in mechanical sensitivity, epidermal thickness, and peripheral nerve profiles in the upper dermis were examined in glabrous skin of rat hind paw after 1, 2, and 4 weeks of ankle joint immobilization by plaster casts. Induction of mechanical hypersensitivity was confirmed after 2 and 4 weeks of joint immobilization. Epidermal thinning and increase in peripheral nerve profiles were observed in skin tissues in immobilized rats. The time course of epidermal thinning and increase in peripheral nerve profiles were similar closely to that of hypersensitivity, with significant differences between the immobilized and control rats after 2 weeks of immobilization, which became even more remarkable at 4 weeks of immobilization. These findings suggest that joint immobilization by cast induces epidermal thinning and increases peripheral nerve profiles in the upper dermis and that these changes might be partly responsible for immobilization-induced hypersensitivity.

Study of the genetic factors predisposing to the development of psoriasis

Many findings confirm the influence of neuropsychic factors on the manifestation and exacerbation of the atopic dermatitis and psoriasis. Nowadays it is assumed that by means of neurotransmitters’ secretion the nervous system can influence different processes, including the immune mediated inflammation, which has the key role in the pathogenesis of such dermatosis. The article hereunder contains comprehensive data on prospective trends of following studies of the nervous regulation participation in the pathogenesis of such dermatosis.

Narrowband ultraviolet B phototherapy for patients with refractory uraemic pruritus: a randomized controlled trial

BACKGROUND

Pruritus is very common in uraemic patients, but the treatment remains challenging. Studies regarding narrowband ultraviolet B (NB-UVB) phototherapy for uraemic pruritus are rare.

OBJECTIVES

To investigate whether or not NB-UVB phototherapy is an effective treatment for uraemic pruritus.

METHODS

We conducted a single-blind, randomized, controlled trial for patients with refractory uraemic pruritus. The treatment group received NB-UVB phototherapy three times per week for 6 weeks. The dose of NB-UVB started from 210 mJ cm(-2) and was increased by 10% each time. The control group received time-matched exposures to long-wave UVA radiation. A visual analogue scale (VAS) score was evaluated weekly for pruritus intensity for 12 weeks. The characteristics of pruritus were also assessed by a questionnaire at baseline and after 6 weeks of phototherapy.

RESULTS

Both the NB-UVB and control groups had significant and comparable improvement in the pruritus intensity VAS scores during the period of phototherapy and follow-up. Compared with the control group, the NB-UVB group showed a significant improvement in the involved body surface area affected by pruritus (P = 0·006), but not in sleep quality. More detailed regression and estimating analysis revealed that the patients in the NB-UVB group had lower pruritus intensity scores at week 6, week 10 and week 12. This may indicate a beneficial difference at certain time points, but the effect seems marginal.

CONCLUSIONS

NB-UVB phototherapy does not show a significant effect in reducing pruritus intensity compared with a control group for refractory uraemic pruritus. Further studies are warranted.

Management of itch in atopic dermatitis

Atopic dermatitis is a common, pruritic, inflammatory skin disorder. Chronic, localized, or even generalized pruritus is the diagnostic hallmark of atopic dermatitis, and its management remains a challenge for physicians. The threshold for itch and alloknesis is markedly reduced in these patients, and infections can promote exacerbation and thereby increase the itch. Modern management consists of anti-inflammatory, occasionally antiseptic, as well as antipruritic therapies to address the epidermal barrier as well as immunomodulation or infection. Mild forms of atopic dermatitis may be controlled with topical therapies, but moderate-to-severe forms often require a combination of systemic treatments consisting of antipruritic and immunosuppressive drugs, phototherapy, and topical compounds. In addition, patient education and a therapeutic regimen to help the patient cope with the itch and eczema are important adjuvant strategies for optimized long-term management. This review highlights various topical, systemic, and complementary and alternative therapies, as well as provide a therapeutic ladder for optimized long-term control of itch in atopic dermatitis.

Neuroprotective effects of a new skin care formulation following ultraviolet exposure

BACKGROUND

Chronic ultraviolet (UV) exposure is a major environmental factor involved in extrinsic skin ageing (photo-ageing). Skin nerve fibres are significantly reduced in number following UV irradiation and new skincare compounds with neuroprotective effects are thus highly warranted.

OBJECTIVES

We developed a new skincare formulation from a plant extract and evaluated its neuroprotective effects of ex vivo UV irradiation.

MATERIALS AND METHODS

The new skincare emulsion was formulated from Echinacea purpurea extract and was enriched with antioxidants (patent no. PROV020110087075). Skin samples were obtained from 20 healthy patients enrolled for plastic surgery and were immediately treated with placebo (SPF 15) or test emulsions. Skin samples were exposed to UVA and UVB for 60 min. Nerve fibres were identified by immunofluorescence using a monoclonal antibody, anti-human CD56. Cell damage was quantified by image analysis.

RESULTS

UVA and UVB significantly reduced (40-60%) densities of nerve endings in control samples treated with placebo (P < 0.001). Samples treated with test emulsion completely blocked UV-related effects on skin nerve endings. These neuroprotective effects were similarly observed regardless of age or tissue analysed (breast versus abdomen).

CONCLUSIONS

Our new skincare formulation obtained from E. purpurea provides important neuroprotective effects of UV irradiation and could be used together with SPFs to prevent chronic deleterious effects of solar exposure.

Inhibitory effects of UV-based therapy on dry skin-inducible nerve growth in acetone-treated mice

BACKGROUND

UV-based therapy has anti-pruritic effects in inflammatory skin diseases, such as atopic dermatitis and psoriasis. These anti-pruritic effects may be partly due to inhibition of intraepidermal nerve growth, but they have not been fully characterized.

OBJECTIVE

This study was performed to characterize the anti-nerve growth effects of UV-based therapies in acetone-treated mice as an acute dry skin model.

METHODS

Nerve fibers penetrate into the epidermis 24h after acetone treatment in mice, and nerve growth peaks 48h after acetone treatment. To investigate the effects of UV-based therapies on the epidermal nerve fibers, including combination treatment with corticosteroid ointment, the mice were treated with psoralen ultraviolet A (PUVA), PUVA and betamethasone valerate ointment (PUVA+BV), narrowband ultraviolet B (NB-UVB), or an excimer lamp. Each therapy was provided 24h after acetone treatment, and skin samples were taken 48h later. Nerve fiber densities and expression levels of nerve growth factor (NGF) and semaphorin 3A (Sema3A) in the epidermis were examined by immunohistochemistry.

RESULTS

Penetration of nerve fibers into the epidermis was observed in the acetone-treated mice, concomitant with increased NGF and decreased Sema3A levels in the epidermis. The acetone-induced intraepidermal nerve growth was significantly decreased by PUVA, PUVA+BV, NB-UVB, and excimer lamp treatments compared with controls. In addition, PUVA+BV and NB-UVB normalized the abnormal expression of NGF and Sema3A in the epidermis, but no such normalization was observed with excimer lamp treatment.

CONCLUSION

UV-based therapies, especially NB-UVB and excimer lamp treatments, may be effective therapeutic methods for pruritus involving epidermal hyperinnervation.

Neurotropin inhibits both capsaicin-induced substance P release and nerve growth factor-induced neurite outgrowth in cultured rat dorsal root ganglion neurones

BACKGROUND

Neurotropin (NTP), a biological extract from rabbit skin inoculated with vaccinia virus, is an effective analgesic and anti-allergic agent, and has antipruritic effects in various dermatoses including eczema, dermatitis and urticaria. In patients receiving haemodialysis who have pruritus, NTP appears to exert its antipruritic effect by lowering the plasma levels of substance P (SP), but its underlying mechanisms are not fully understood.

AIM

To investigate the antipruritic mechanisms of NTP.

METHODS

The effects of NTP on capsaicin-induced SP release from neonatal rat dorsal root ganglion (DRG) neurones were assessed by measuring SP concentrations in culture media by a competitive ELISA. The effects of NTP on nerve growth factor (NGF)-induced neurite outgrowth were assessed by measuring the length of the longest process of cultured DRG neurones. The neuronal cytotoxicity of NTP was determined using a methylthiazole tetrazolium cytotoxicity assay.

RESULTS

NTP dose-dependently inhibited capsaicin-induced release of SP from cultured DRG neurones, whereas NTP alone had no effect on SP release. Moreover, NTP dose-dependently inhibited NGF-induced neurite outgrowth in cultured DRG neurones. NTP had no observable cytotoxicity.

CONCLUSIONS

These results suggest that NTP exerts its antipruritic effects by inhibiting both SP release and neurite outgrowth of cutaneous sensory nerves.

Severity of disease, rather than xerosis, correlates with pruritus in patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic, relapsing skin disease characterized by xerosis and pruritus. As pruritus is an unpleasant sensation and the associated scratching aggravates the skin eruption considerably, it is important to control this symptom when treating AD. Dry skin is generally considered to be a potential cause of pruritus in xerotic skin diseases, but a clear correlation between pruritus and atopic xerosis has not been demonstrated. Aim To examine the contribution of atopic xerosis to the development of pruritus in AD.

METHODS

Twenty-two patients with AD (12 males and 10 females; mean age, 27.5 years) were examined. Xerosis and the severity of disease were evaluated using the Objective Severity Assessment of Atopic Dermatitis (OSAAD) and the SCORing Atopic Dermatitis (SCORAD) index, respectively. A modified SCORAD index was calculated by removing the symptoms potentially associated with pruritus (intensity of itching and insomnia) from the standard SCORAD index. Pruritus was evaluated using both a visual analog scale and the Verbal Itch Score.

RESULTS

The severity of AD (modified SCORAD index) correlated better than atopic xerosis (OSAAD score) with both pruritus scores, possibly indicating that the use of appropriate anti-inflammatory agents may be helpful in controlling pruritus as well as skin eruption in AD.

CONCLUSION

Our data suggest that the severity of disease (or skin inflammation) provides a greater contribution than xerosis to the development of pruritus in AD.

Effects of ultraviolet radiation on human cutaneous nerve fibres

Due to an increasing number of skin diseases as a result of exposure to ultraviolet (UV) radiation, it is necessary to evaluate the effectiveness of new skin care formulations with broad-spectrum sunscreens.

OBJECTIVES

This study aims to assess the status of nerve fibres in healthy human skin, to quantify effects of UV radiation on nerve endings, and to evaluate neuroprotective effects of new skin care formulations against UV exposure damage.

METHODS

Samples were obtained from 34 female patients enrolled for plastic surgery and were immediately treated (10 min) with three emulsions: Cream 1, Cream 2 (placebo) and a sunscreen with sun protection factor 15 (SPF15). Control samples and those treated with the cream emulsions were exposed to UVA and UVB for 60 min. Nerve fibres were identified by immunofluorescence using a monoclonal antibody (anti-human CD56/NCAM). Cell damage was assessed by image analysis.

RESULTS

Several cellular nervous structures were identified in the skin samples, including free nerve endings. UVA and UVB significantly decreased (40-60%) density of nerve endings in the control samples and those treated with placebo (Cream 2) or SPF15 (all P < 0.001). Cream 1 completely blocked effects of UV radiation on nerve endings (P > 0.05 vs. control).

CONCLUSIONS

Quantification of cell damage induced by UV radiation provides useful information for identification of new skin care compounds with neuroprotective properties.

[Atopic dermatitis and stress? How do emotions come into skin?]

It is widely accepted, that stress can induce or exacerbate atopic dermatitis. The physiological mechanisms that mediate this negative influence of stress on atopic dermatitis are not clearly understood. This topic has been actively investigated in recent years focusing on neuroimmunological, psychoendocrinological studies and examination of integrity and function of skin barrier under stress. Different neuropeptides and neurotrophins seem to play an important role in stress-induced neurogenic inflammation and connection of nervous and immune system. Mast cells play a key role in the development of inflammatory reaction to stress. Skin barrier is altered by stress by means of increased cortisol level. Thereby lamellar body secretion is decreased and epidermal expression of antimicrobial peptides (beta-defensin and cathelicidin) is down-regulated. We review recent investigations in this field.