Industrial Production and Therapeutic Application of Botulinum Neurotoxin: The Role of C. botulinum Type A

Botulinum neurotoxin has remarkably transitioned from a food safety hazard and biological warfare to an effective therapeutic drug. Currently, botulinum neurotoxins have seven serotypes (BoNT/A-G) in the form of protein complexes produced by Clostridium, a gram-positive and sporeforming bacteria. The conversion of toxins into useful drug substances of choice using the biotechnological process is tremendously increasing. Recent studies have shown that Botulinum neurotoxin-A (BoNT/A) has different biological activities and potencies in experimental and clinical conditions. They also indicate that the manufacturing process influences the potency and efficacy of BoNT/A drugs. Thus, this review focuses on the following criteria: detailed Fed-batch operation that includes the upstream and downstream processing of BoNT/A, the underlying mechanism behind the neurotoxic effect, and commercially available FDA-approved BoNT/A products and their therapeutic uses. Still, some research gaps exist in the mechanism for the treatment of psychiatric disorders.

Prolonged Antipruritic Effect of Botulinum Toxin Type A on Cowhage-induced Itch: A Randomized, Single-blind, Placebo-controlled Trial

Botulinum toxin type A (Botox) is thought to have antipruritic effects through inhibition of pruritic factors, including acetylcholine, substance P, and glutamate. The aim of this randomized, single-blind, placebo-controlled trial was to test the effect of botulinum toxin type A on cowhage, a non-histaminergic model for chronic itch. Botulinum toxin type A was injected into the arm of 35 healthy subjects, with a saline control injected into the contralateral arm. Thermal sensory parameters (warmth and heat thresholds and heat pain intensity) and itch intensity after cowhage application were examined on test areas. Botulinum toxin type A reduced itch intensity, overall perceived itch (area under the curve (AUC); percentage change from baseline), and peak itch intensity compared with the control at 1 week, 1 month, and 3 months. Botulinum toxin type A had no effect on thermal thresholds or heat pain intensity. In conclusion, botulinum toxin type A reduced cowhage itch for at least 3 months, which suggests that botulinum toxin type A is a potential long-lasting treatment for localized, non-histaminergic itch.

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.

Off-Label Use of Botulinum Toxin in Dermatology—Current State of the Art

Botulinum toxin (BoNT) is a neurotoxin produced by the Clostridium botulinum bacteria. Among seven different isoforms, only BoNT-A and BoNT-B are commercially used. Currently, botulinum toxin has been indicated by the U.S. Food and Drug Administration in several disorders, among others: chronic migraine, hyperhidrosis, urinary incontinence from detrusor overactivity, or cosmetics. However, there are numerous promising reports based on off-label BTX usage, indicating its potential effectiveness in other diseases, which remains unknown to many. Among them, dermatological conditions, such as rosacea, annal fissure, Raynaud phenomenon, hypertrophic scars and keloids, and also hidradenitis suppurativa, are currently being investigated. This article aims to provide a comprehensive update on the off-label use of botulinum toxin in dermatology, based on an analysis and summary of the published literature.

Toxicology and pharmacology of botulinum and tetanus neurotoxins: an update

Tetanus and botulinum neurotoxins cause the neuroparalytic syndromes of tetanus and botulism, respectively, by delivering inside different types of neurons, metalloproteases specifically cleaving the SNARE proteins that are essential for the release of neurotransmitters. Research on their mechanism of action is intensively carried out in order to devise improved therapies based on antibodies and chemical drugs. Recently, major results have been obtained with human monoclonal antibodies and with single chain antibodies that have allowed one to neutralize the metalloprotease activity of botulinum neurotoxin type A1 inside neurons. In addition, a method has been devised to induce a rapid molecular evolution of the metalloprotease domain of botulinum neurotoxin followed by selection driven to re-target the metalloprotease activity versus novel targets with respect to the SNARE proteins. At the same time, an intense and wide spectrum clinical research on novel therapeutics based on botulinum neurotoxins is carried out, which are also reviewed here.

The impact of external factors on psoriasis

Psoriasis is one of the most common chronic inflammatory skin diseases, constituting a significant health and socioeconomic problem. Despite numerous therapeutic options, the results of treatment very often remain insufficient. It is extremely important to remember that many external factors impact the effectiveness of therapy. This article discusses the importance of emollients in therapy and the influence of infectious agents and injuries on the course of psoriasis. Understanding the above-mentioned factors in the treatment of psoriasis is critical to achieve satisfactory therapeutic effects.

Utilities of Botulinum Toxins in Dermatology and Cosmetology

Botulinum toxin (BoNT) is a neurotoxin produced by the Clostridium botulinum bacterium with a well-known efficacy and safety profile in the focal idiopathic hyperhidrosis treatment. BoNT comprises seven different neurotoxins; however, only toxins A and B are clinically employed. BoNT is lately practiced in off-label therapies for a variety of skin diseases. Scar prevention, hyperhidrosis, rhytides, eccrine nevus, alopecia, psoriasis, Darier disease, bullous skin disease, pompholyx and Raynaud's phenomenon are some of the novel indications for BoNT in cosmetic and notably non-cosmetic aspects of dermatology. To employ BoNT correctly in clinical practice, we must have a thorough understanding of the functional anatomy of the mimetic muscles. An intensive literature search was conducted to update all dermatology-oriented experiments and clinical trials on the described element of BoNT for this general overview of BoNT use in dermatology. This review aims to analyse the role of BoNT in dermatology and cosmetology.

Botulinum toxin type-A versus 5-fluorouracil in the treatment of plaque psoriasis: Comparative study

BACKGROUND

Long-term remission and total clearance in Psoriasis can only be achieved in a few patients.

AIM

To compare the efficacy and safety of intradermal Botulinum toxin (BTX) in the treatment of plaque psoriasis.

SUBJECTS AND METHODS

A comparative study conducted in thirty-five patients with chronic plaque psoriasis was treated by split-body therapy. The patients were either treated with intradermal BTX or with intralesional 5-fluorouracil (5-FU) to each of 2 bilaterally symmetrical psoriatic plaque lesions. The outcomes were assessed using the following criteria: the sum of erythema, scaling, and induration scores and the clearing percentage of the target plaque lesion assessed by 2 blinded observers.

RESULTS

At the end of the study, the response rate was 85% on the BTX treatment side and 90% on the 5-FU side. There was no significant difference between both sides regarding a clinical response or side effects. The recurrence rate was 15% on both sides.

CONCLUSIONS

Botulinum toxin was a novel, safe, single injection, and effective therapy for plaque-type psoriasis. More studies are required to further prove the efficacy of BTX in the treatment of plaque psoriasis.

Genital and Inverse/Intertriginous Psoriasis: An Updated Review of Therapies and Recommendations for Practical Management

Genital and inverse psoriasis can develop in more than one-third of patients who have psoriasis. Psoriatic plaques in the genital and intertriginous skin are challenging to treat because the skin is thin and often occluded, making it more sensitive to certain therapies. Traditional guidelines indicate topical therapies, such as corticosteroids, topical calcineurin inhibitors (TCI), and vitamin D analogs as first-line recommendation in treating genital and inverse psoriasis. There have been developments in the treatment of genital and inverse psoriasis using systemic therapies, including IL-17 inhibitors and PDE-4 inhibitors.

Therapeutic Use of Botulinum Neurotoxins in Dermatology: Systematic Review

Botulinum toxin is a superfamily of neurotoxins produced by the bacterium Clostridium Botulinum with well-established efficacy and safety profile in focal idiopathic hyperhidrosis. Recently, botulinum toxins have also been used in many other skin diseases, in off label regimen. The objective of this manuscript is to review and analyze the main therapeutic applications of botulinum toxins in skin diseases. A systematic review of the published data was conducted, following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Botulinum toxins present several label and off-label indications of interest for dermatologists. The best-reported evidence concerns focal idiopathic hyperhidrosis, Raynaud phenomenon, suppurative hidradenitis, Hailey–Hailey disease, epidermolysis bullosa simplex Weber–Cockayne type, Darier’s disease, pachyonychia congenita, aquagenic keratoderma, alopecia, psoriasis, notalgia paresthetica, facial erythema and flushing, and oily skin. Further clinical trials are still needed to better understand the real efficacy and safety of these applications and to standardize injection and doses protocols for off label applications.

Alternative Clinical Indications of Botulinum Toxin

Botulinum toxin type A (BoNTA) is a powerful neurotoxin that inhibits acetylcholine release from presynaptic vesicles. The potency and safety profile of BoNTA grant the toxin vast therapeutic potential. It has been used off-label for a variety of dermatologic conditions. This review aims to analyze published literature regarding the benefits and risks of the off-label use of BoNTA beyond facial lines, including eccrine hidrocystomas, enlarged pores, keloids and hypertrophic scars, hidradenitis suppurativa, hyperhidrosis, masseter muscle hypertrophy, and salivary gland hypertrophy, among others. A MEDLINE search from January 2000 to December 2019 was conducted on the off-label uses of botulinum toxin in dermatology.

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.

Interventions in the B-type natriuretic peptide signalling pathway as a means of controlling chronic itch

Chronic itch poses major health care and economic burdens worldwide. In 2013, B-type natriuretic peptide (BNP) was identified as an itch-selective neuropeptide and shown to be both necessary and sufficient to produce itch behaviour in mice. Since then, mechanistic studies of itch have increased, not only at central levels of the spinal relay of itch signalling but also in the periphery and skin. In this review, we have critically analysed recent findings from complementary pharmacological and physiological approaches, combined with genetic strategies to examine the role of BNP in itch transduction and modulation of other pruritic proteins. Additionally, potential targets and possible strategies against BNP signalling are discussed for developing novel therapeutics in itch. Overall, we aim to provide insights into drug development by altering BNP signalling to modulate disease symptoms in chronic itch, including conditions for which no approved treatment exists.

Inverse Psoriasis: From Diagnosis to Current Treatment Options

Inverse psoriasis represents a clinical variant of psoriasis that is sometimes difficult to diagnose due to its clinical similarity with other skin disorders involving the folds, mainly including mechanical intertrigo, fungal and bacterial infections, contact dermatitis, seborrheic dermatitis, and lichen planus. Dermoscopy represents a useful tool for an enhanced non-invasive diagnosis. The treatment of inverse psoriasis may be challenging and include topical corticosteroids, topical calcineurin inhibitors, vitamin D analogs, traditional oral systemic therapies such as cyclosporine and methotrexate, and biologic therapies.

Lesional upregulation of SLURP1 immunostaining parallels disease severity in psoriasis vulgaris patients

BACKGROUND AND OBJECTIVES

The exact pathogenesis of psoriasis is still unclear. SLURP1 is vital for the normal differentiation of keratinocytes, and could therefore be involved in psoriasis. In this study we investigated the immunohistochemical staining reaction of SLURP1 in psoriasis vulgaris patients and its possible relation to disease pathogenesis.

PATIENTS AND METHODS

20 patients with psoriasis vulgaris, 20 patients with psoriasiform dermatitis and 20 normal skin samples were studied. Psoriasis severity was measured with a combination of PASI and DLQI scores. Lesional and non-lesional sites were biopsied for each psoriasis patient. A single biopsy sample was taken for cases with psoriasiform dermatitis and for controls. All sections were immunostained for SLURP1 according to the manufacturer's protocol.

RESULTS

Significant differences were noted in SLURP1 immunostaining between lesional and non-lesional biopsies of psoriasis patients and between lesional biopsies of psoriasis patients and lesional sites of psoriasiform dermatitis. However, the differences between non-lesional biopsies of psoriasis patients and normal controls were not significant. Furthermore, the grading of SLURP1 immunostaining paralleled the degree of psoriasis severity.

CONCLUSIONS

SLURP1 immunostaining is significantly increased in lesional skin of psoriasis vulgaris and not in psoriasiform dermatitis, which demonstrates the role of SLURP1 in the pathogenesis of psoriasis. SLURP1 could be used as a biological marker for psoriasis severity, and this hypothesis warrants further investigation.

The epithelial immune microenvironment (EIME) in atopic dermatitis and psoriasis

The skin provides both a physical barrier and an immunologic barrier to external threats. The protective machinery of the skin has evolved to provide situation-specific responses to eliminate pathogens and to provide protection against physical dangers. Dysregulation of this machinery can give rise to the initiation and propagation of inflammatory loops in the epithelial microenvironment that result in inflammatory skin diseases in susceptible people. A defective barrier and microbial dysbiosis drive an interleukin 4 (IL-4) loop that underlies atopic dermatitis, while in psoriasis, disordered keratinocyte signaling and predisposition to type 17 responses drive a pathogenic IL-17 loop. Here we discuss the pathogenesis of atopic dermatitis and psoriasis in terms of the epithelial immune microenvironment-the microbiota, keratinocytes and sensory nerves-and the resulting inflammatory loops.

Hochregulation der SLURP1-Immunfärbung in Läsionen von Psoriasis-vulgaris-Patienten entspricht dem Schweregrad der Erkrankung

HINTERGRUND UND ZIELE

Die genaue Pathogenese der Psoriasis ist immer noch ungeklärt. Da SLURP1 wichtig ist für die normale Differenzierung von Keratinozyten, könnte es bei Psoriasis eine Rolle spielen. In dieser Studie untersuchten wir die immunhistochemische Färbung von SLURP1 bei Patienten mit Psoriasis vulgaris und deren möglichen Zusammenhang mit der Pathogenese der Erkrankung.

PATIENTEN UND METHODEN

Es wurden Hautproben von 20 Patienten mit Psoriasis vulgaris, von 20 Patienten mit psoriasiformer Dermatitis sowie 20 normale Hautproben untersucht. Der Schweregrad der Psoriasis wurde anhand einer Kombination von PASI- und DLQI-Scores gemessen. Bei allen Psoriasis-Patienten wurden Biopsate aus läsionalen und aus nichtläsionalen Hautpartien entnommen. Bei psoriasiformer Dermatitis und Kontrollen wurde jeweils nur ein Hautbiopsat entnommen. Alle Schnitte wurden, entsprechend des Hersteller-Protokolls, einer SLURP1-Immunfärbung unterzogen.

ERGEBNISSE

Hinsichtlich der SLURP1-Immunfärbung wurden zwischen läsionalen und nichtläsionalen Biopsaten von Psoriasis-Patienten sowie zwischen läsionalen Biopsaten von Psoriasis-Patienten und Patienten mit psoriasiformer Dermatitis signifikante Unterschiede festgestellt. Die Unterschiede zwischen nichtläsionalen Biopsaten von Psoriasis-Patienten und normalen Hautproben waren jedoch nicht signifikant. Darüber hinaus war der Grad der SLURP1-Immunanfärbung proportional zum Schweregrad der Psoriasis.

SCHLUSSFOLGERUNGEN

Bei Psoriasis vulgaris ist die SLURP1-Immunfärbung in läsionaler Haut signifikant erhöht, nicht jedoch bei psoriasiformer Dermatitis. Dies spricht für eine Rolle von SLURP1 bei der Pathogenese der Psoriasis. SLURP1 lässt sich möglicherweise als biologischer Marker für den Schweregrad der Psoriasis einsetzen, wobei diese Hypothese noch weiterer Untersuchungen bedarf.

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.

Antipruritic Effects of Botulinum Neurotoxins

This review explores current evidence to demonstrate that botulinum neurotoxins (BoNTs) exert antipruritic effects. Both experimental and clinical conditions in which botulinum neurotoxins have been applied for pruritus relief will be presented and significant findings will be highlighted. Potential mechanisms underlying antipruritic effects will also be discussed and ongoing challenges and unmet needs will be addressed.

Pharmacotherapeutic approaches for treating psoriasis in difficult-to-treat areas

INTRODUCTION

Despite great therapeutic advancements in psoriasis, four notable difficult-to-treat areas including the scalp, nails, intertriginous (including genitals), and palmoplantar regions, pose a challenge to both physicians and patients. Localized disease of these specific body regions inflicts a significant burden on patients' quality of life and requires an adequate selection of treatments.

AREAS COVERED

This manuscript discusses appropriate therapies and important treatment considerations for these difficult-to-treat areas based on the available clinical data from the literature.

EXPERT OPINION

Clinical trials assessing therapies for the difficult-to-treat areas have been inadequate. With the first biological clinical trial for genital psoriasis pending publication, it is with hope that other biological agents will be evaluated for region-specific psoriasis. A greater understanding of the genetic and immunologic aspects of regional psoriasis, as well as identification of unique biomarkers, will further guide management decisions. For example, the recent discovery of the IL-36 receptor gene for generalized pustular psoriasis may prove valuable for other forms of psoriasis. Ultimately, identification of the most beneficial treatments for each psoriasis subtype and difficult-to-treat area will provide patients with maximal quality of life.

Botulinum Toxin in the Field of Dermatology: Novel Indications

Since its approval by the US Food and Drug Administration in 2002 for glabellar wrinkles, botulinum toxin (BTX) has been widely used to correct facial wrinkles. As a result, many consider BTX synonymous with cosmetic dermatology. Recent studies indicate that BTX elicits biological effects on various skin cell types via the modulation of neurotransmitter release, and it seems that BTX has a wider zone of dermatologic influence than originally understood. Clinicians and researchers are now beginning to explore the potential of BTX beyond the amelioration of facial lines and encouraging results are seen with BTX in a variety of skin conditions. In this paper, we review novel dermatological indications of BTX which includes (but not limited to) scar prevention, facial flushing, post-herpetic neuralgia and itch. These areas show great promise, but there is definite need for larger, double-blinded, randomized control trials against established treatments before BTX becomes a clinical reality.

New Uses of AbobotulinumtoxinA in Aesthetics

BotulinumtoxinA (BoNT-A) is now widely established for the main approved indication of reducing glabellar lines, and is also widely used off-label to improve the appearance of wrinkles and lines in other parts of the face. The number of aesthetic procedures continues to increase as the patient population becomes more diverse, in particular with increasing numbers of people of color and men. Further developments in treatment may continue to expand the audience for BoNT-A by making procedures more comfortable and by delivering a more natural, less static appearance. These may be achieved through use of combinations of BoNT-A with other aesthetic procedures, tailoring the dose of toxin to the patient's muscle mass or by using novel injection and application techniques. Beyond amelioration of facial lines, encouraging results have been seen with the use of BoNT-A to improve the appearance of hypertrophic and keloid scars and even to prevent them. Studies have been conducted with scars in various parts of the body and further research is ongoing. Dermatological and other medical uses for BoNT-A are also active areas of research. Injections of BoNT-A have been shown to reduce signs and symptoms of acne, rosacea, and psoriasis, to reduce neuromuscular pain, and to bring about significant improvements in a number of rare diseases that are caused or exacerbated by hyperhidrosis. This paper reviews these new uses for BoNT-A, looking at the rationale for their use and discussing the results of published case studies and clinical trials. These areas have shown great promise to date, but more and larger clinical studies will be required before these treatments become a clinical reality. To this end details are also provided of clinical trials currently listed in the main clinical trials database to highlight research areas of particular interest.

AbobotulinumtoxinA: A 25-Year History

During the late 1960s and early 1970s, Alan Scott showed that intramuscular injections of botulinum toxin (BoNT) corrected nonaccommodative strabismus without resorting to surgery. The UK doctors who trained with Scott soon realized the significant potential offered by BoNT type A as a therapeutic option for several difficult-to-treat diseases. This led to a collaboration between these pioneering clinicians and the Centre for Applied Microbiology and Research at Porton Down, United Kingdom, and, in turn, to the development and commercialization of abobotulinumtoxinA as Dysport (Dystonia/Porton Down; Ipsen Biopharm Ltd., Wrexham, UK). Dysport was approved in Europe for the treatment of specific dystonias in December 1990 and now has marketing authorizations in 75 countries. Since then, the use of BoNT in therapeutic and aesthetic indications has grown year-on-year, and continues to expand well beyond Scott's initial aim. For example, ongoing trials are assessing potential new indications for BoNT-A, including acne and psoriasis. Furthermore, a growing number of other BoNT products, often termed "biosimilars," together with innovative formulations of well-established BoNT types, are likely to reach the market over the next few years. This review focuses on the history of Dysport to mark the 25th anniversary of its first launch in the United Kingdom.

Botulinum Toxin Off-Label Use in Dermatology: A Review

BACKGROUND

Botulinum toxin is a neurotoxin produced by the bacterium Clostridium botulinum which causes a flaccid muscle paralysis. It is currently used for aesthetic treatments and in the focal hyperhidrosis. Recently, botulinum toxin has also been used experimentally in many other dermatological conditions with good results.

OBJECTIVE

To review and analyze the possible botulinum toxin off-label applications published.

METHODS

A retrospective review of the published data was conducted.

CONCLUSIONS

this potent drug can lead to several off-label indications of interest for dermatologists. Further clinical trials are still needed to better understand the real efficacy and safety of these applications and to standardize injection and dose protocols.

Cutaneous Surgical Denervation: A Method for Testing the Requirement for Nerves in Mouse Models of Skin Disease

Cutaneous somatosensory nerves function to detect diverse stimuli that act upon the skin. In addition to their established sensory roles, recent studies have suggested that nerves may also modulate skin disorders including atopic dermatitis, psoriasis and cancer. Here, we describe protocols for testing the requirement for nerves in maintaining a cutaneous mechanosensory organ, the touch dome (TD). Specifically, we discuss methods for genetically labeling, harvesting and visualizing TDs by whole-mount staining, and for performing unilateral surgical denervation on mouse dorsal back skin. Together, these approaches can be used to directly compare TD morphology and gene expression in denervated as well as sham-operated skin from the same animal. These methods can also be readily adapted to examine the requirement for nerves in mouse models of skin pathology. Finally, the ability to repeatedly sample the skin provides an opportunity to monitor disease progression at different stages and times after initiation.

Aesthetic uses of the botulinum toxin

The cosmetic use of botulinum toxin (BoNT) is the most common cosmetic procedure performed in the world today. Common adverse events seen in the aesthetic use of the BoNT include swelling, localized bruising, headaches, injection site discomfort, excessive muscle weakness, and unintended paresis of adjacent muscles. BoNT has a wide array of cosmetic uses, including treatment of glabellar lines, chemical browlift, forehead wrinkles, periorbital, and perioral lines. The future formulations and applications of BoNT type A will be plentiful, and are exciting to consider.

Intralesional therapy for psoriasis

Localized resistant plaques of psoriasis often remain despite highly effective anti-psoriasis treatment. Intralesional therapy is often used to treat various malignant, infectious or inflammatory cutaneous diseases, including psoriasis. Despite the presence of many review articles on the treatment of psoriasis, no articles exist which review the use of intralesional therapy for psoriasis. In this article, we review the published literatures of intralesional therapy for psoriasis. Corticosteroids, methotrexate, cyclosporin, biologics, botulinum toxin type-A, 15-hydroxyeicosatetraenoic acid, and chemotherapy agents such as 5-fluorouracil are discussed. Also, agents which may be used intralesionally and have the potential to treat psoriasis will also be reviewed such as bleomycin, vincristine or vinblastine, mitomycin-C, aminophylline, 5-aminolevulinic acid, rituximab, bevacizumab and pentoxifylline are included.

A succinct review of botulinum toxin in dermatology; update of cosmetic and noncosmetic use

Botulinum toxin A has a wide variety of clinical applications in medical and dermatologic sciences. Nowadays, researchers introduce some other indications for botulinum toxin in cosmetic and especially noncosmetic aspects of dermatology such as medical rhinoplasty, hypertrophic scar, chemical brow lift, supraciliary wrinkles, pompholix, eccrine angiomatosis, Hailey-Hailey, dermatochalasis, lichen simplex, nosthalgia parestetica, and granulosis rubra nasi. In this general overview of the use of botulinum toxin in dermatology, an extensive literature search was carried out to updates of all dermatology-oriented experiments and clinical trials on the mentioned aspect of botulinum toxin.

Inverse psoriasis: case presentation and review

Inverse psoriasis is a rare form of psoriasis that affects between 3% and 7% of psoriasis patients. Its appearance and distribution in the flexural skin folds makes it a difficult disease to diagnose, and because it is thought of as a variant of psoriasis, there are very few studies that deal with it exclusively. We present a short case report of inverse psoriasis and a review of the literature on various facets of this disease: epidemiology, histology, clinical presentation, differential diagnosis, and treatment.

Treatment of pachydermoperiostosis pachydermia with botulinum toxin type A

BACKGROUND

Pachydermoperiostosis (PDP) is a rare hereditary disorder characterized by digital clubbing, periostosis, and pachydermia. Pachydermia results in leonine facies, a major cause of cosmetic and functional morbidity in these patients. Its treatment is usually surgical. So far, no medical treatment has been suggested to alleviate this morbidity.

OBJECTIVE

We sought to assess the role of botulinum toxin type A (BTX-A) in improving the cosmetic appearance of pachydermia in patients with PDP.

METHODS

Three patients with PDP were treated with BTX-A for their leonine facies. A total of 70 to 80 U were used to treat the upper third of the face. Photographs were taken at baseline and at 2 and 6 weeks after the injections. The patients were followed up periodically for at least 6 months. Wrinkle severity was assessed at relaxation using the 4-point facial wrinkle scale at baseline, week 6, and month 6. In addition, a subjective assessment of the improvement of the extent and depth of the facial rhytides/furrows over the upper third of the face was performed by the same investigator at week 6 and month 6.

RESULTS

Using the subjective assessment of the improvement of wrinkles, all 3 patients exhibited a fair to excellent response at week 6 that started manifesting 1 week after the BTX-A treatment. All patients demonstrated a residual effect 6 months after the treatment. One patient exhibited a mild exacerbation of his ptosis.

LIMITATIONS

Major limitations were the small number of patients and the administration of BTX-A injections and assessment of their response by a single unblinded physician.

CONCLUSION

BTX-A is a simple procedure that may be of value in temporarily improving the cosmetic appearance of pachydermia in patients with PDP.

Botulinum toxin type A reduces histamine-induced itch and vasomotor responses in human skin

BACKGROUND

Clinical evidence has revealed the antipruritic effect of botulinum toxin type A (BoNT/A). BoNT/A is believed to be effective against itch as it inhibits the release of acetylcholine as well as some other substances that may be involved in itch.

OBJECTIVES

To investigate the effect of subcutaneous administration of BoNT/A on experimentally histamine-induced itch in human skin.

METHODS

In this double-blind, placebo-controlled study, 14 healthy men (mean +/- SD age 26.3 +/- 2.6 years) received BoNT/A (Botox; Allergan, Irvine, CA, U.S.A.; 5 U) and isotonic saline on the volar surface of either forearm. Histamine prick tests were performed four times at the treatment sites (before treatment, and days 1, 3 and 7 after treatment). The itch intensity (as rated on a 0-10 visual analogue scale), itch area, neurogenic inflammation (visible flare area), blood flow (laser Doppler) and cutaneous temperature (thermographic images) were measured over the course of the trials.

RESULTS

BoNT/A reduced the histamine-induced itch intensity (F(1,39) = 30.2, P < 0.001) and itch area (F(1,39) = 8.8, P = 0.011) compared with saline at all time points after treatment. The duration of itch was also shorter for BoNT/A-treated areas (F(1,39) = 19.4, P < 0.001), with a peak effect at day 7. The flare area was smaller in the BoNT/A-treated arm compared with the saline-treated arm at all time points after treatment (F(1,39) = 15.4, P = 0.002). Findings from blood flow (F(1,26) = 177.3, P < 0.001) and temperature measurements (F(1,26) = 27.6, P < 0.001) clearly showed the suppressive effect of BoNT/A on vasomotor reactions, with the maximal effect on days 3 and 7.

CONCLUSIONS

BoNT/A reduced the itch intensity, blood flow and neurogenic inflammation in response to the histamine prick test in human skin. The findings could be applicable in the treatment of some pruritic conditions that can be difficult to treat with conventional treatments.