Botulinum Neurotoxin Type A in the Treatment of Facial Seborrhea and Acne: Evidence and a Proposed Mechanism

Intradermal injection of botulinum neurotoxin is a frequently performed procedure in aesthetic dermatology to improve facial skin tone, texture, fine wrinkles, and enlarged pores. In practice, botulinum neurotoxin type A is also used to reduce skin oiliness of the face. There is increasing evidence that acetylcholine plays specific roles in sebum production, suggesting that botulinum neurotoxin type A may reduce sebum production by interfering with cholinergic transmission between sebaceous glands and autonomic nerve terminals. Botulinum neurotoxins can also inhibit several pathogenetic components of acne development, suggesting that botulinum neurotoxins can be used as a safe and effective treatment modality for acne and other skin disorders related to overactivity of sebaceous glands. This review aims to explore the current evidence behind the treatment of facial seborrhea and acne with botulinum neurotoxin type A.     

Anatomical Proposal for Botulinum Neurotoxin Injection Targeting the Platysma Muscle for Treating Platysmal Band and Jawline Lifting: A Review

The platysma muscle is a thin superficial muscle that covers the entire neck and lower part of the face. The platysma muscle is the primary target muscle for botulinum neurotoxin injection therapy aimed at treating platysmal band and lower facial lifting. In the procedure of botulinum neurotoxin injection therapy, a lack of knowledge of the anatomy of the platysma muscle and the properties of botulinum neurotoxin can lead to side effects such as dysphagia, dysphonia, and weakness of the neck muscles. Anatomically safe injection sites have been proposed for the platysma muscle, and the appropriate injection technique has been reviewed. We proposed optimal injection sites based on the external anatomical features of the mandible. The aim of these proposal was to standardize the procedure for the effective use of botulinum neurotoxin injections by minimizing the dose unit and injection points and thereby preventing adverse events.     

Botulinum versus tetanus neurotoxins: Why is botulinum neurotoxin but not tetanus neurotoxin a food poison?

Botulinum and tetanus neurotoxins, produced by Clostridium botulinum and Clostridium tetani, respectively, are the most poisonous poisons known to mankind. Although botulinum and tetanus neurotoxins share several characteristics, such as similar mol. wts, similar macrostructure, virtually identical mode of action, and a strong amino acid sequence homology, the two neurotoxins differ in one very significant way; only botulinum neurotoxin is a food poison. Factors responsible for the food poisoning potential of botulinum neurotoxins seem to be a group of complexing proteins that are also produced by C. botulinum, and are known to associate with the neurotoxin. Translation products of nucleotide sequences upstream to the neurotoxin genes of serotypes A, B, C, D, E and F botulinum neurotoxin reveal the location of genes for one of the complexing proteins that could be transcribed as polycistronic mRNA to include neurotoxin sequences. No such protein seems to be present in C. tetani, suggesting that the lack of complexing proteins might be responsible for tetanus not being a food poison.     

Pharmaceutical,Biological, and Clinical Properties of Botulinum Neurotoxin Type A Products

Botulinum neurotoxin injections are a valuable treatment modality for many therapeutic indications and have revolutionized the field of aesthetic medicine so that they are the leading cosmetic procedure performed worldwide. Studies show that onabotulinumtoxinA, abobotulinumtoxinA, and incobotulinumtoxinA are comparable in terms of clinical efficacy. Differences between the products relate to the botulinum neurotoxin complexes, specific biological potency, and their immunogenicity. Protein complex size and molecular weight have no effect on biological activity, stability, distribution, or side effect profile. Complexing proteins and inactive toxin (toxoid) content increase the risk of neutralizing antibody formation, which can cause secondary treatment failure, particularly in chronic disorders that require frequent injections and long-term treatment. These attributes could lead to differences in therapeutic outcomes, and, given the widespread aesthetic use of these three neurotoxin products, physicians should be aware of how they differ to ensure their safe and effective use.     

Therapeutic Applications of Botulinum Neurotoxin for Autonomic Symptoms in Parkinson’s Disease: An Updated Review

Parkinson’s disease is the most common age-related motoric neurodegenerative disease. In addition to the cardinal motor symptoms of tremor, rigidity, bradykinesia, and postural instability, there are numerous non-motor symptoms as well. Among the non-motor symptoms, autonomic nervous system dysfunction is common. Autonomic symptoms associated with Parkinson’s disease include sialorrhea, hyperhidrosis, gastrointestinal dysfunction, and urinary dysfunction. Botulinum neurotoxin has been shown to potentially improve these autonomic symptoms. In this review, the varied uses of botulinum neurotoxin for autonomic dysfunction in Parkinson’s disease are discussed. This review also includes discussion of some additional indications for the use of botulinum neurotoxin in Parkinson’s disease, including pain.     

A sensitive and useful radioimmunoassay for neurotoxin and its haemagglutinin complex from Clostridium botulinum

A sensitive radioimmunoassay for the detection of botulinum toxin, produced by Clostridium botulinum, was developed. This employs homogeneous botulinum neurotoxin type A and its 125I-labelled derivative of high specific radioactivity, rather than its complex with haemagglutinin as used hitherto. The sensitivity of the assay is 1 ng of neurotoxin per ml, which is equivalent to 80 LD50 units (half-lethal doses) in mice. Neurotoxin and its complex with haemagglutinin were measurable with equal sensitivity when using antibodies against botulinum neurotoxin type A. Specificity of the assay was demonstrated by the lack of response to type B and E botulinum toxins and to heat-inactivated botulinum toxin or extracts of Clostridium sporogenes strain BL46, which contains many surface antigenic determinants common to Clostridium botulinum. Using appropriate conditions, neurotoxin added to fish extract could be quantified accurately, proportionality being observed between the amounts of standard toxin added. In addition, the amounts of toxin species produced by culturing Clostridium botulinum in canned fish was measurable; the values obtained were comparable to those observed by the mouse bioassay. Moreover, the fish samples gave a dose-response curve in the competition radioimmunoassay which was paralleled by the response of botulinum neurotoxin standards. This assay offers the most sensitive, reliable immunological method available for the quantitation of molecular forms of botulinum toxin. As the technique can be used with unpurified fish extracts, it should be widely applicable to different types of samples contaminated with botulinum toxin; furthermore, the clinical diagnosis of human botulism could be substantiated with this method.     

Gastrointestinal smooth muscles and sphincters spasms: treatment with botulinum neurotoxin

More than fifty years following the discovery that botulinum neurotoxins inhibit neuromuscular transmission, these powerful poisons have become drugs with many indications. First used to treat strabismus, local injections of botulinum neurotoxin are now considered a safe and efficacious treatment for neurological and non-neurological conditions. One of the most recent achievements in the field is the observation that botulinum neurotoxin is a treatment for diseases of the gastrointestinal tract. Botulinum neurotoxin is not only potent in blocking skeletal neuromuscular transmission, but also block cholinergic nerve endings in the autonomic nervous system. The capability to inhibit contraction of smooth muscles of the gastrointestinal tract was first suggested based on in vitro observations and later demonstrated in vivo; it has also been shown that botulinum neurotoxin does not block non adrenergic non cholinergic responses mediated by nitric oxide. This has further promoted the interest to use botulinum neurotoxin as a treatment for overactive smooth muscles and sphincters, such as the lower esophageal sphincter to treat esophageal achalasia, or the internal anal sphincter to treat anal fissure. Information on the anatomical and functional organization of innervation of the gastrointestinal tract is a prerequisite to understand many features of botulinum neurotoxin action on the gut and the effects of injections placed into specific sphincters. This review presents current data on the use of botulinum neurotoxin to treat diseases of the gastrointestinal tract and summarizes recent knowledge on the pathogenesis of disorders of the gut due to a dysfunction of the enteric nervous system.     

Dysport: Pharmacological properties and factors that influence toxin action

The pharmacological properties of Dysport^® that influence toxin action are reviewed and compared with other botulinum toxin products. In particular, the subject of diffusion is examined and discussed based upon the evidence that currently exists, both from laboratory studies and from clinical data. Diffusion of botulinum toxin products is not related to the size of the toxin complex in the product since the complex dissociates under physiological conditions, releasing the naked neurotoxin to act. The active neurotoxin in Type A products is the same and therefore diffusion is equal when equal doses are administered.     

Binding activity and immunogenic characterization of recombinant C-terminal quarter and half of the heavy chain of botulinum neurotoxin serotype A

In the present study, we explored and compared the binding activity and immunogenic characterization of the most effective part corresponding to C-terminal quarter of heavy chain of botulinum neurotoxin serotype A (AHc-C) with C-terminal half of heavy chain of botulinum neurotoxin serotype A (AHc). Firstly, the fully soluble AHc-C protein successfully expressed in Escherichia coli by co-expression with thioredoxin (Trx) was shown to bind with ganglioside as the AHc, indicating that the recombinant AHc-C protein retains a functionally active conformation. Furthermore, a solid-phase assay showed that the anti-AHc-C sera effectively inhibited the binding of AHc or AHc-C to the ganglioside GT1b, the first step in BoNT/A intoxication of neurons, as good as the anti-AHc sera. Finally, although the recombinant AHc-C protein still induced a high serum antibody titers and afforded protection level as the mice challenged with active botulinum neurotoxin serotype A, the immunization with AHc protein induced stronger protective potency than the AHc-C protein. The data presented in the report shows that there are the same ganglioside binding activity and different immunogenic characterization between the C-terminal quarter and half of heavy chain of botulinum neurotoxin serotype A. Therefore, the recombinant AHc-C protein can not only be developed into a minimal subunit candidate vaccine for prophylaxis against botulinum neurotoxin serotype A but also be used as a promising tool in the search for binding inhibitors and chimeric vaccines.     

Novel Anatomical Guidelines on Botulinum Neurotoxin Injection for Wrinkles in the Nose Region

Botulinum neurotoxin injection surrounding the nose area is frequently used in aesthetic settings. However, there is a shortage of thorough anatomical understanding that makes it difficult to treat wrinkles in the nose area. In this study, the anatomical aspects concerning the injection of botulinum neurotoxin into the nasalis, procerus, and levator labii superioris alaeque muscles are assessed. In addition, the present knowledge on localizing the botulinum neurotoxin injection point from a newer anatomy study is assessed. It was observed that, for the line-associated muscles in the nose region, the injection point may be more precisely defined. The optimal injection sites are the nasalis, procerus, and levator labii superioris alaeque muscles, and the injection technique is advised. We advise the best possible injection sites in association with anatomical standards for commonly injected muscles to increase efficiency in the nose region by removing the wrinkles. Similarly, these suggestions support a more precise procedure.     

Prevention and treatment of bacterial diseases caused by bacterial bioterrorism threat agents

There is general consensus that the bacterial agents or products most likely to be used as weapons of mass destruction are Bacillus anthracis, Yersinia pestis, Francisella tularensis and the neurotoxin of Clostridium botulinum. Modern supportive and antimicrobial therapy for inhalational anthrax is associated with a 45% mortality rate, reinforcing the need for better adjunctive therapy and prevention strategies. Pneumonic plague is highly contagious, difficult to recognize and is frequently fatal. Therefore, the development of vaccines against this agent is crucial. Although tularemia is associated with low mortality, the highly infectious nature of aerosolized F. tularensis poses a substantive threat that is best met by vaccine development. Safer antitoxins and a vaccine are required to meet the threat of the use of botulinum toxin as a weapon of mass destruction. In this article, the current status of research in these areas is reviewed.     

Novel Anatomical Proposal for Botulinum Neurotoxin Injection Targeting Lateral Canthal Rhytids

Botulinum neurotoxin injections near the lateral canthal rhytids are commonly used in cosmetic settings; however, there is a lack of thorough anatomical knowledge, and an effective way to treat them with accumulating knowledge is needed. The anatomical characteristics concerning the injection of botulinum neurotoxin into the orbicularis oculi muscle were evaluated in this review. Current knowledge on the identification of botulinum neurotoxin injection points from recent anatomical research was assessed. The lateral canthal lines are involved with the orbicularis oculi muscle and nearby anatomical structures, and the injection points can be more precisely defined. The best possible injection sites were provided, and the injection procedure was described. This review proposes evidence for injection sites associated with the surface anatomy of the orbicularis oculi muscles to enhance the effectiveness of easing lateral canthal rhytids.     

Xeomin is free from complexing proteins

In contrast to the other botulinum toxin products Xeomin only contains the 150 kD neurotoxin without complexing proteins which have no therapeutic function and don't influence the diffusion of the neurotoxin. In large clinical Phase III studies (blepharospasm and cervical dystonia) Xeomin showed the same efficacy and profile of adverse events as Botox. Whereas competing product must be stored refrigerated, Xeomin is stable for 3 years at room temperature.     

The mechanism underlying the protective effect of the thearubigin fraction of black tea (Camellia sinensis) extract against the neuromuscular blocking action of botulinum neurotoxins

The aim of the present study was to elucidate the mechanism of the protective effect of black tea extract, the thearubigin fraction, against the neuromuscular blocking action of botulinum neurotoxin types A, B, and E. The effects of thearubigin fraction extracted from a black tea infusion were examined on the neuromuscular blocking action of botulinum neurotoxin types A, B, and E in mouse phrenic nerve-diaphragm preparations and on the binding of these toxins to rat cerebrocortical synaptosomes. Botulinum neurotoxin type A (1.5 nM), B (6 nM), or E (5 nM) abolished indirect twitches in mouse phrenic nerve-diaphragm preparations within 50, 90, 90 min., respectively. Thearubigin fraction mixed with each toxin blocked the inhibitory effect of the toxins. The specific binding of [125I]botulinum neurotoxin type A, B, or E to rat cerebrocortical synaptosomes was inhibited by mixing iodinated toxin with thearubigin fraction. The elution profile of [125I]botulinum neurotoxin type A, B, or E on Sephadex G-50 column chromatography was different from that of toxin mixed with thearubigin fraction. These findings indicate that thearubigin fraction protects against the neuromuscular blocking action of botulinum neurotoxin types A, B, and E by binding with the toxins.     

Botulinum Neurotoxin Serotypes Detected by Electrochemical Impedance Spectroscopy

Botulinum neurotoxin is one of the deadliest biological toxins known to mankind and is able to cause the debilitating disease botulism. The rapid detection of the different serotypes of botulinum neurotoxin is essential for both diagnosis of botulism and identifying the presence of toxin in potential cases of terrorism and food contamination. The modes of action of botulinum neurotoxins are well-established in literature and differ for each serotype. The toxins are known to specifically cleave portions of the SNARE proteins SNAP-25 or VAMP; an interaction that can be monitored by electrochemical impedance spectroscopy. This study presents a SNAP-25 and a VAMP biosensors for detecting the activity of five botulinum neurotoxin serotypes (A–E) using electrochemical impedance spectroscopy. The biosensors are able to detect concentrations of toxins as low as 25 fg/mL, in a short time-frame compared with the current standard methods of detection. Both biosensors show greater specificity for their compatible serotypes compared with incompatible serotypes and denatured toxins.     

Structural analysis of the catalytic domain of tetanus neurotoxin.

Clostridium neurotoxins, comprising the tetanus neurotoxin and the seven antigenically distinct botulinum neurotoxins (BoNT/A-G), are among the known most potent bacterial protein toxins to humans. Although they have similar function, sequences and three-dimensional structures, the substrate specificity and the selectivity of peptide bond cleavage are different and unique. Tetanus and botulinum type B neurotoxins enzymatically cleave the same substrate, vesicle-associated membrane protein, at the same peptide bond though the optimum length of substrate peptide required for cleavage by them is different. Here, we present the first experimentally determined three-dimensional structure of the catalytic domain of tetanus neurotoxin and analyze its active site. The structure provides insight into the active site of tetanus toxin's proteolytic activity and the importance of the nucleophilic water and the role of the zinc ion. The probable reason for different modes of binding of vesicle-associated membrane protein to botulinum neurotoxin type B and the tetanus toxin is discussed. The structure provides a basis for designing a novel recombinant vaccine or structure-based drugs for tetanus.     

The translocation of botulinum A neurotoxin by chromaffin cells is promoted in low ionic strength solution and is insensitive to trypsin

Botulinum A neurotoxin (BoNtx) produced a partial inhibition of carbachol induced 3H-noradrenaline (3H-NA) release from bovine adrenal chromaffin cells in monolayer culture. Each of the polysialogangliosides GD1a, GT1b and GD1b enhanced the block of exocytosis when they were applied prior to the toxin exposure. The monosialoganglioside GM1 was not effective. Chromaffin cells treated with neuraminidase lost their sensitivity to BoNtx. Application of gangliosides to these cells, however, restored their susceptibility to the toxin. Treatment of the cells with trypsin did not affect the BoNtx-blockade of 3H-NA-release. The potency of botulinum A toxin was increased in a solution of low ionic strength in which sodium chloride was replaced by sucrose. In agreement with the potency of botulinum A neurotoxin in blocking exocytosis under the various conditions, binding of 125I-botulinum A neurotoxin to chromaffin cells was enhanced in low ionic strength solution and by pretreatment of the cells with gangliosides. The binding was decreased by digestion of gangliosides with neuraminidase. It is concluded that botulinum A neurotoxin binds exclusively to polysialogangliosides which subsequently serve as carriers for the toxin. The low ionic strength may increase some physico-chemical interaction of the toxin with the polysialogangliosides.     

Anatomical Proposal for Botulinum Neurotoxin Injection for Glabellar Frown Lines

Botulinum neurotoxin injection for treating glabellar frown lines is a commonly used method; however, side effects, such as ptosis and samurai eyebrow, have been reported due to a lack of comprehensive anatomical knowledge. The anatomical factors important for the injection of the botulinum neurotoxin into the corrugator supercilii muscle has been reviewed in this study. Current understanding on the localization of the botulinum neurotoxin injection point from newer anatomy examination was evaluated. We observed that for the glabellar-frown-line-related muscles, the injection point could be more accurately demarcated. We propose the injection method and the best possible injection sites for the corrugator supercilii muscle. We propose the optimal injection sites using external anatomical landmarks for the frequently injected muscles of the face to accelerate effective glabellar frown line removal. Moreover, these instructions would support a more accurate procedure without adverse events.     

Protein Domain Analysis of C. botulinum Type A Neurotoxin and Its Relationship with Other Botulinum Serotypes

Botulinum neurotoxins (BoNTs) are highly potent poisons produced by seven serotypes of Clostridium botulinum. The mechanism of neurotoxin action is a multistep process which leads to the cleavage of one of three different SNARE proteins essential for synaptic vesicle fusion and transmission of the nerve signals to muscles: synaptobrevin, syntaxin, or SNAP-25. In order to understand the precise mechanism of neurotoxin in a host, the domain structure of the neurotoxin was analyzed among different serotypes of C. botulinum. The results indicate that neurotoxins type A, C, D, E and F contain a coiled-coil domain while types B and type G neurotoxin do not. Interestingly, phylogenetic analysis based on neurotoxin sequences has further confirmed that serotypes B and G are closely related. These results suggest that neurotoxin has multi-domain structure, and coiled-coil domain plays an important role in oligomerisation of the neurotoxin. Domain analysis may help to identify effective antibodies to treat Botulinum toxin intoxication.     

The zinc-dependent protease activity of the botulinum neurotoxins

The botulinum neurotoxins (BoNT, serotypes A-G) are some of the most toxic proteins known and are the causative agents of botulism. Following exposure, the neurotoxin binds and enters peripheral cholinergic nerve endings and specifically and selectively cleaves one or more SNARE proteins to produce flaccid paralysis. This review centers on the kinetics of the Zn-dependent proteolytic activities of these neurotoxins, and briefly describes inhibitors, activators and factors underlying persistence of toxin action. Some of the structural, enzymatic and inhibitor data that are discussed here are available at the botulinum neurotoxin resource, BotDB (http://botdb.abcc.ncifcrf.gov).