Botulinum toxin: a novel therapeutic option for bronchial asthma?

Perspectives for the use of therapeutic Botulinum toxin as a multifaceted candidate drug to attenuate COVID-19

The recent outbreak of coronavirus disease (COVID-19) resulting from a distinctive severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continues to evolve in many countries and pose life-threatening clinical issues to global public health. While the lungs are the primary target for the SARS-CoV-2-mediated pathological consequence, the virus appears to invade the brain and cause unpredicted neurological deficits. In the later stage, COVID-19 can progress to pneumonia, acute respiratory failure, neurodegeneration and multi-organ dysfunctions leading to death. Though a significant portion of individuals with COVID-19 has been recovering from clinical symptoms, the pathological impact of the SARS-CoV-2 infection on the structural and functional properties of the lungs, heart, brain and other organs at the post-recovery state remains unknown. Presently, there is an urgent need for a remedial measure to combat this devastating COVID-19. Botulinum toxins (BoNTs) are potent neurotoxins that can induce paralysis of muscle and acute respiratory arrest in humans. However, a mild dose of the purified form of BoNT has been known to attenuate chronic cough, dyspnoea, pneumonia, acute respiratory failure, abnormal circulation, cardiac defects and various neurological deficits that have been recognised as the prominent clinical symptoms of COVID-19. Considering the fact, this review article provides 1) an overview of the SARS-CoV-2 mediated pathological impact on the lungs, heart and brain, 2) signifies the therapeutic uses of BoNTs against pulmonary failure, cardiac arrest and neurological deficits, and 3) emphasize the rationality for the possible use of BoNT to prevent SARS-CoV-2 infection and manage COVID-19.

Towards new uses of botulinum toxin as a novel therapeutic tool

The uses of botulinum toxin in the fields of neurology, ophthalmology, urology, rehabilitation medicine and aesthetic applications have been revolutionary for the treatment of patients. This non-invasive therapeutic has continually been developed since first discovered in the 1970s as a new approach to what were previously surgical treatments. As these applications develop, so also the molecules are developing into tools with new therapeutic properties in specific clinical areas. This review examines how the botulinum toxin molecule is being adapted to new therapeutic uses and also how new areas of use for the existing molecules are being identified. Prospects for future developments are also considered.

Botulinum toxin, Quo Vadis?

Botulinum toxin (BTX), derived from the exotoxin of Clostridium botulinum, cleaves Soluble N-ethylmaleimide-sensitive factor-Attachment protein REceptor (SNARE) proteins, causing chemodenervation of cholinergic neurons. BTX also inhibits exocytosis of vesicles containing norepinephrine, glutamate, substance P and calcitonin gene-related peptide (CGRP) and inhibits expression of the vanilloid receptor. Clinical applications of BTX, which include the treatment of overactive skeletal and smooth muscles, hypersecretory and painful disorders, have increased exponentially since it was first used clinically to treat strabismus more than two decades ago. In this editorial, we discuss reports of new therapeutic indications of BTX, and propose new areas for research.

Topical botulinum toxin to treat hyperhidrosis? No sweat!

Palmar, plantar and axillary hyperhidrosis, though benign, may be burdensome and occupationally restrictive, even hazardous. Treatment modalities range from topical antiperspirants, iontophoresis, systemic medications such as anticholinergics and benzodiazepines and injections of botulinum toxin, to thoracic sympathectomy. Intradermal injections of botulinum toxin (BTX), though effective, are painful especially when multiple injections are required. Iontophoretic administration of BTX has been described, the BTX entering the eccrine sweat glands via the sweat pores and through the sweat ducts. We postulate that BTX can be administered topically, either unassisted or assisted by application of an electrical gradient, low-frequency ultrasound or excipients such as dimethylsulfoxide. We examine the rationale and feasibility for such a treatment modality and route of administration.

Where has all the botox gone? (How) will we ever learn… Using monoclonal antibodies to track botulinum toxin

Botulinum toxin (BTX) is an important therapeutic tool in the treatment of overactive skeletal and smooth muscles, as well as hypersecretory and painful disorders. Despite advances in our understanding of how BTX works, much remains to be elucidated, such as how BTX ameliorates pain, how it produces weakness remote from the site of injection and the fate of the heavy and light chain components of the BTX molecule following endocytosis into the presynaptic membrane. BTX, conjugated to radionuclides, allows investigators to track the molecule both in vitro and in vivo. However, altering the BTX molecule may cause structural changes or pharmacokinetic and pharmacodynamic alterations, and disrupt its normal action. We propose instead to bind the biomarkers (appropriate dyes, radionuclides or MRI contrast agents) to monoclonal antibodies directed against either heavy or light chain components of BTX, thus allowing administration of native (i.e. unaltered) BTX.