Botulinum toxin type A suppresses arterial vasoconstriction by regulating calcium sensitization and the endothelium-dependent endothelial nitric oxide synthase/soluble guanylyl cyclase/cyclic guanosine monophosphate pathway: An in vitro study

Evaluation of the Effect of Botulinum Toxin A on the Lymphatic Endothelial Cells

INTRODUCTION

Botulinum toxin A (BoTA) is a neurotoxin formed by Clostridium botulinum, with a broad medical application spectrum. While the primary effect of BoTA is on the muscles, the effects of BoTA in other systems including the blood vasculature have already been examined, revealing unexpected actions. However, no studies exist to the best of our knowledge regarding the potential effects of BoTA on the lymphatic vascular system, possessing a critical role in health and disease. Isolated human lymphatic endothelial cells (LECs) were cultured in dedicated in vitro culture systems. The analysis including imaging and cell culture approaches as well as molecular biology techniques is performed to examine the LEC alterations occurring upon exposure to different concentrations of BoTA.

MATERIALS AND METHODS

Human LECs were cultured and expanded on collagen-coated petri dishes using endothelial basal medium and the commercial product Botox from Allergan as used for all our experiments. Harvested cells were used in various in vitro functional tests to assess the morphologic and functional properties of the BoTA-treated LECs. Gene expression analysis was performed to assess the most important lymphatic system-related genes and pathways.

RESULTS

Concentrations of 1, 5 or 10 U of BoTA did not demonstrate a significant effect regarding the proliferation and migration capacity of the LECs versus untreated controls. Interestingly, even the smallest BoTA dose was found to significantly decrease the cord-like-structure formation capacity of the seeded LECs. Gene expression analysis was used to underpin possible molecular alterations, suggesting no significant effect of BoTA in the modification of gene expression versus the starvation medium control.

CONCLUSION

LECs appear largely unaffected to BoTA treatment, with an isolated effect on the cord-like-structure formation capacity. Further work needs to assess the effect of BoTA on the smooth-muscle-cell-covered collecting lymphatic vessels and the possible aesthetic implications of such an effect, due to edema formation.

LEVEL OF EVIDENCE V

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A Phase III Clinical Study of the Efficacy and Safety of Botulinum Toxin Type A (MASPORT) with DYSPORT for the Treatment of Glabellar Lines

BACKGROUND

Botulinum toxin type A is a widely used treatment of facial wrinkles. The objective of this study was to compare the efficacy and safety of a new botulinum toxin type A (Masport [abobotulinum toxin A], MasoonDarou Co) with DYSPORT® for the treatment of glabellar lines.

METHODS

262 subjects with moderate-to-severe glabellar lines received either a fixed dose of 50 units of MASPORT® or DYSPORT® (Ipsen Company, England). Subjects were followed up at 14, 30, 60, 90 and 120 days after injection. Efficacy was assessed by investigator at maximum frown and rest and also by Subject Global Assessment of Change (SGA). The responders were defined as persons with +2 grade improvement from baseline for both investigator and patient assessment. The occurrence and duration of adverse effects were recorded up throughout the study.

RESULTS

According to the investigator evaluations, the responder rate at maximum frown were 94.5% for MASPORT and 95.6% for DYSPORT group on day 30 and at rest were 85.45% and 85.68% for MASPORT and DYSPORT group, respectively. According to the subject self-assessment, the proportion of responders in MASPORT group at day 30 was 95.28% versus 97.04% for DYSPORT group. No serious drug related adverse effect was recorded in either study groups, and the rates of adverse effects were similar for both groups.

CONCLUSION

Abobotulinum toxin A [MASPORT] is equally safe and effective as commercial product [DYSPORT] for the treatment of glabellar lines with the dose of 50 units, up to 120 days.

LEVEL OF EVIDENCE I

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Botulinum Toxin Type a for Treating Rest Pain in Chronic Limb-threatening Ischemia: A Case Report

Botulinum toxin type A (BoNT/A) is a potent neurotoxin with widely use range, for the good outcomes in the treatment of pain, it was considered as an unique analgesic drugs with the feature of sustained efficacy after a single application, but up to now, treating chronic limb-threatening ischemia (CLTI) with BoNT/A was rarely reported. We present a 91-year-old man with CLTI, the main clinical manifestations were left foot rest pain, intermittent claudication and toe necrosis, the patient refused invasive treatments, and the pain failure to respond to conventional analgesic drugs, the subcutaneous injections of BoNT/A was performed to the patient. The pain score on the visual analog scale (VAS), decreased from 5-6 (before treatment) to 1 within days after infiltration, and keep in 1-2 of VAS during follow-up. Our case report demonstrated that BoNT/A may be an unique minimally invasive solution for treating rest pain in CLTI.

Botulinum Toxin: A Potential Cardiovascular Agent?

Botulinum neurotoxin (BoNT) is a toxin with a wide repertoire of well-known applications in cosmetics and medicine, such as treating migraine headaches, spasticity, and achalasia, and it has generally been shown to be safe and well-tolerated. In addition to its current successes in clinical practice, studies have also demonstrated the potential of BoNT to be used as a therapeutic agent for many cardiovascular conditions. Prior investigations, as well as trials currently underway, have showcased the safety and potential efficacy of BoNT in applications such as treating ischemia-reperfusion injury, hypertension, atrial fibrillation, and heart failure. While further study in humans, as well as improved statistical power in efficacy studies, are needed before its prospective use as a treatment for the aforementioned conditions, one might consider BoNT a potential cardiovascular agent.

Gi-protein-coupled β 1-adrenergic receptor: re-understanding the selectivity of β 1-adrenergic receptor to G protein

β ₁-adrenergic receptor (β ₁-AR), a member in the family of G-protein-coupled receptors, is a transmembrane receptor of great significance in the heart. Physiologically, catecholamines activate β ₁-AR to initiate a positive chronotropic, inotropic, and dromotropic change. It is believed that β ₁-AR couples to Gs protein and transmits the signal through second messenger cAMP. However, increasing research shows that β ₁-AR can also bind with Gi protein in addition to Gs. When β ₁-AR-Gi is biasedly activated, cardioprotective effects are introduced by the activated cGMP-protein kinase G (PKG) pathway and the transactivation of epidermal growth factor receptor (EGFR) pathway. The discovery of β ₁-AR-Gi signaling makes us reconsider the selectivity of G protein with regard to β ₁-AR, which also provides new ideas for the treatment of heart diseases. This review summarizes the discovery of β ₁-AR-Gi pathway, including the evidence that supports β ₁-AR's capability to couple Gi, details of the transduction process and functions of the β ₁-AR-Gi signaling pathway.

Preclinical Evidence for the Role of Botulinum Neurotoxin A (BoNT/A) in the Treatment of Peripheral Nerve Injury

Traumatic peripheral nerve injuries tend to be more common in younger, working age populations and can lead to long-lasting disability. Peripheral nerves have an impressive capacity to regenerate; however, successful recovery after injury depends on a number of factors including the mechanism and severity of the trauma, the distance from injury to the reinnervation target, connective tissue sheath integrity, and delay between injury and treatment. Even though modern surgical procedures have greatly improved the success rate, many peripheral nerve injuries still culminate in persistent neuropathic pain and incomplete functional recovery. Recent studies in animals suggest that botulinum neurotoxin A (BoNT/A) can accelerate nerve regeneration and improve functional recovery after injury to peripheral nerves. Possible mechanisms of BoNT/A action include activation or proliferation of support cells (Schwann cells, mast cells, and macrophages), increased angiogenesis, and improvement of blood flow to regenerating nerves.

BoNT/A in the Urinary Bladder-More to the Story than Silencing of Cholinergic Nerves

Botulinum neurotoxin (BoNT/A) is an FDA and NICE approved second-line treatment for overactive bladder (OAB) in patients either not responsive or intolerant to anti-cholinergic drugs. BoNT/A acts to weaken muscle contraction by blocking release of the neurotransmitter acetyl choline (ACh) at neuromuscular junctions. However, this biological activity does not easily explain all the observed effects in clinical and non-clinical studies. There are also conflicting reports of expression of the BoNT/A protein receptor, SV2, and intracellular target protein, SNAP-25, in the urothelium and bladder. This review presents the current evidence of BoNT/A’s effect on bladder sensation, potential mechanisms by which it might exert these effects and discusses recent advances in understanding the action of BoNT in bladder tissue.

Botulinum Toxin in the Treatment of Vasopressor-associated Symmetric Peripheral Gangrene

Symmetric peripheral gangrene (SPG) affects peripheral tissues of critically ill patients and can have severe disfiguring and debilitating effects. It can occur in the setting of multiple conditions, and it is associated with the use of vasopressors. There are no evidence-based treatments available for patients who develop SPG. Botulinum toxin has emerged as a potential therapy in vasospastic disorders, and we hypothesized that it may be used in the treatment of tissue ischemia in critically ill patients on vasopressors. We present a case of a patient who developed vasopressor-associated SPG and who experienced complete resolution after local injection with botulinum toxin. While the action of botulinum toxin on skeletal muscle is best understood, it has also been demonstrated to attenuate the release of multiple vasoconstrictive factors that impact vascular smooth muscle and modulate calcium and nitric oxide. These effects may result in vasodilation and improvement of cutaneous ischemia when injected locally. Clinicians may consider this local therapy in the treatment of vasopressor-associated symmetric peripheral gangrene.