Botulinum toxin abolishes sweating via impaired sweat gland responsiveness to exogenous acetylcholine

Longitudinal Assessment of Facial Hyperhidrosis Management: Evaluating the Utility and Quality of Life Improvements following Botulinum Toxin Injection

Facial hyperhidrosis is a debilitating condition that can severely impact the quality of life. This study aimed to assess the long-term utility of Botulinum toxin type A therapy (BTA) for facial hyperhidrosis and its impact on quality of life over a one-year period. Conducted at the Pius Brinzeu Clinical Emergency Hospital in Timisoara, Romania, this longitudinal observational study involved 77 adult patients with primary facial hyperhidrosis. Participants received two sessions of Botulinum toxin injections (50 U IncoBTX-A each) and were evaluated at baseline, 6 months, and 12 months using the Hyperhidrosis Disease Severity Scale (HDSS), WHOQOL-BREF, Dermatology Life Quality Index (DLQI), and a bespoke survey. The study demonstrated significant reductions in HDSS scores from 3.6 ± 0.5 to 1.2 ± 0.8 post-treatment, sustained at 1.3 ± 0.6 at 12 months (p-value < 0.001). DLQI scores markedly decreased from 24.8 ± 4.2 to 6.2 ± 2.1 post-treatment, stabilizing at 6.5 ± 2.5 at 12 months (p-value < 0.001). Sweat production significantly dropped from 0.75 g ± 0.15 to 0.18 g ± 0.07 per 15 min (p-value < 0.001). WHOQOL-BREF scores improved notably in the mental domain from 66.7 ± 6.1 to 70.8 ± 5.2 at 12 months (p-value < 0.001), with physical and social domains also showing significant improvements. Correlation analysis revealed strong negative correlations between DLQI total score and HDSS (rho = -0.72, p-value < 0.001) and sweat production (rho = -0.68, p-value < 0.001). Regression analysis indicated significant predictors for DLQI total score, including HDSS (B Coefficient = -3.8, p-value < 0.001) and sweat production (B Coefficient = -2.2, p-value < 0.001). BTA therapy significantly improved the quality of life in facial hyperhidrosis patients, with lasting effects on symptom severity, sweat production, and quality of life domains. The correlation and regression analyses further substantiated the treatment's impact on both physical and psychological aspects. These findings advocate Botulinum toxin as a viable long-term treatment for facial hyperhidrosis.

Interkingdom Hormonal Regulations between Plants and Animals Provide New Insight into Food Safety

Food safety has become an attractive topic among consumers. Raw material production for food is also a focus of social attention. As hormones are widely used in agriculture and human disease control, consumers' concerns about the safety of hormone agents have never disappeared. The present review focuses on the interkingdom regulations of exogenous animal hormones in plants and phytohormones in animals, including physiology and stress resistance. We summarize these interactions to give the public, researchers, and policymakers some guidance and suggestions. Accumulated evidence demonstrates comprehensive hormonal regulation across plants and animals. Animal hormones, interacting with phytohormones, help regulate plant development and enhance environmental resistance. Correspondingly, phytohormones may also cause damage to the reproductive and urinary systems of animals. Notably, the disease-resistant role of phytohormones is revealed against neurodegenerative diseases, cardiovascular disease, cancer, and diabetes. These resistances derive from the control for abnormal cell cycle, energy balance, and activity of enzymes. Further exploration of these cross-kingdom mechanisms would surely be of greater benefit to human health and agriculture development.

A Phase 3, Randomized, Multi-center Clinical Trial to Evaluate the Efficacy and Safety of Neu-BoNT/A in Treatment of Primary Axillary Hyperhidrosis

BACKGROUND

Botulinum toxin type A is widely used to treat primary axillary hyperhidrosis and has proven to be an effective and safe approach. Onabotulinumtoxin A was approved by the FDA as a treatment for primary axillary hyperhidrosis. This study aimed to evaluate the efficacy and safety of Neu-BoNT/A in subjects diagnosed with primary axillary hyperhidrosis.

METHODS

The Hyperhidrosis Disease Severity Scale, gravimetric measurement of sweat, and Global Assessment Scale were analyzed at weeks 4, 8, 12, and 16 to determine the effect of treatment. Adverse events, physical examination, and vital signs were monitored.

RESULTS

Subjects treated with Neu-BoNT/A showed statistically significant improvement by all 3 methods at weeks 4, 8, 12, and 16 (P value = 0.00). There were no severe adverse events or significant changes in vital signs, physical examination, or laboratory tests.

CONCLUSION

Neu-BoNT/A can be effectively and safely used for primary axillary hyperhidrosis.

LEVEL OF EVIDENCE II

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 .

Impact of Cutaneous Blood Flow on NIR-DCS Measures of Skeletal Muscle Blood Flow Index

Near-infrared diffuse correlation spectroscopy (NIR-DCS) is an optical technique for estimating relative changes in skeletal muscle perfusion during exercise, but may be affected by changes in cutaneous blood flow, as photons emitted by the laser must first pass through the skin. Accordingly, the purpose of this investigation was to examine how increased cutaneous blood flow affects NIR-DCS blood flow index (BFI) at rest and during exercise using a passive whole-body heating protocol that increases cutaneous, but not skeletal muscle, perfusion in the uncovered limb. BFI and cutaneous perfusion (laser Doppler flowmetry) were assessed in 15 healthy young subjects before (e.g., rest) and during 5-minutes of moderate-intensity hand-grip exercise in normothermic conditions and after cutaneous blood flow was elevated via whole-body heating. Hyperthermia significantly increased both cutaneous perfusion (~7.3-fold; p≤0.001) and NIR-DCS BFI (~4.5-fold; p≤0.001). Although relative BFI (i.e., fold-change above baseline) exhibited a typical exponential increase in muscle perfusion during normothermic exercise (2.81±0.95), there was almost no change in BFI during hyperthermic exercise (1.43±0.44). A subset of 8 subjects were subsequently treated with intradermal injection of botulinum toxin-A (Botox) to block heating-induced elevations in cutaneous blood flow, which 1) nearly abolished the hyperthermia-induced increase in BFI, and 2) restored BFI kinetics during hyperthermic exercise to values that were not different from normothermic exercise (p=0.091). Collectively, our results demonstrate that cutaneous blood flow can have a substantial, detrimental impact on NIR-DCS estimates of skeletal muscle perfusion and highlight the need for technical and/or pharmacological advancements to overcome this issue moving forward.

Emerging Opportunities in Human Pluripotent Stem-Cells Based Assays to Explore the Diversity of Botulinum Neurotoxins as Future Therapeutics

Botulinum neurotoxins (BoNTs) are produced by Clostridium botulinum and are responsible for botulism, a fatal disorder of the nervous system mostly induced by food poisoning. Despite being one of the most potent families of poisonous substances, BoNTs are used for both aesthetic and therapeutic indications from cosmetic reduction of wrinkles to treatment of movement disorders. The increasing understanding of the biology of BoNTs and the availability of distinct toxin serotypes and subtypes offer the prospect of expanding the range of indications for these toxins. Engineering of BoNTs is considered to provide a new avenue for improving safety and clinical benefit from these neurotoxins. Robust, high-throughput, and cost-effective assays for BoNTs activity, yet highly relevant to the human physiology, have become indispensable for a successful translation of engineered BoNTs to the clinic. This review presents an emerging family of cell-based assays that take advantage of newly developed human pluripotent stem cells and neuronal function analyses technologies.

Hyperhidrosis and Aesthetics

When one considers the avalanche of new indications and uses for botulinum toxins, it is truly surprising that this has all happened in such a short time. And the safety and dependability of these products are profound, when used appropriately. There is still much to be discovered about the potential of this agent when you contemplate the profound non-cosmetic benefits reported by clinicians and scientists from around the world. The mechanism of action has been studied in depth, and yet the benefits appreciated by people with chronic migraine or major depressive disorder, for instance, are unlikely to be explained by our current mechanistic understanding. Given that these toxins control acetylcholine at the motor end plates, and given that acetylcholine is central to practically every cell in the body, it will not be surprising to find that botulinum toxin researchers will be enjoying many decades of fruitful studies. The advent of the non-surgical aesthetic physician has helped push the clinical utilization of botulinum toxins well beyond its original adoption by oculoplastic surgeons in their patients with blepharospasm. We can expect that the next edition of this book to have a dozen or more new indications which will surprise us all.

Global warming, heat-related illnesses, and the dermatologist

Global warming, provoked by the greenhouse effect of high levels of atmospheric gases (most notably carbon dioxide and methane), directly threatens human health and survival. Individuals vary in their capacity to tolerate episodes of extreme heat. Because skin is the organ tasked with heat dissipation, it is important for dermatologists to be versed in the physiology of cutaneous heat dissipation and cognizant of clinical settings in which the skin’s thermoregulatory responses may be impaired. When the external temperature is lower than that of the skin, the skin releases internal heat through direct thermal exchange with the environment, a process that is aided by an expansion of cutaneous blood flow and eccrine sweating. Cooling through the evaporation of sweat is effective even when the external temperature exceeds that of skin. Many factors, including environmental and physiological (e.g., age and sex), and pathological (e.g., preexisting illnesses, disorders of eccrine function, and medications) considerations, affect the skin’s capacity to thermoregulate. Identification of individuals at increased risk for heat-related morbidity and mortality will become increasingly important in the care of patients.

Botulinum toxin: Pharmacology and injectable administration for the treatment of primary hyperhidrosis

Hyperhidrosis is a dermatological condition defined by excessive sweating beyond thermoregulatory needs with significant effects on patients' quality of life. Hyperhidrosis is categorized as primary or secondary: primary hyperhidrosis is mostly focal and idiopathic, whereas secondary hyperhidrosis is commonly generalized and caused by an underlying medical condition or use of medications. Various surgical and nonsurgical therapies exist for primary hyperhidrosis. Although botulinum toxin is one of the deadliest toxins known, when used in small doses, it is one of the most effective therapies for primary hyperhidrosis. Botulinum toxin injections are widely used as a second-line primary hyperhidrosis treatment option once topical treatment strategies have failed. This article provides an overview of the commercially available botulinum toxin formulations and their applications in the treatment of primary hyperhidrosis.

Sweating as a heat loss thermoeffector

In humans, sweating is the most powerful autonomic thermoeffector. The evaporation of sweat provides by far the greatest potential for heat loss and it represents the only means of heat loss when air temperature exceeds skin temperature. Sweat production results from the integration of afferent neural information from peripheral and central thermoreceptors which leads to an increase in skin sympathetic nerve activity. At the neuroglandular junction, acetylcholine is released and binds to muscarinic receptors which stimulate the secretion of a primary fluid by the secretory coil of eccrine glands. The primary fluid subsequently travels through a duct where ions are reabsorbed. The end result is the expulsion of hypotonic sweat on to the skin surface. Sweating increases in proportion with the intensity of the thermal challenge in an attempt of the body to attain heat balance and maintain a stable internal body temperature. The control of sweating can be modified by biophysical factors, heat acclimation, dehydration, and nonthermal factors. The purpose of this article is to review the role of sweating as a heat loss thermoeffector in humans.

The scientific legacy of Stephen Rothman

The year 2014 marks the centennial of events that led to the First World War ("the war to end all wars") following the assassination of Archduke Ferdinand of the crumbling Austro-Hungarian Empire. It also marks the 120th anniversary of the birth of Stephen Rothman and the 60th anniversary of the publication of his epic textbook The Physiology and Biochemistry of the Skin. In this review, we document our belief that Rothman had a seismic impact on moving investigative dermatology from a medical backwater to a scientific discipline that can hold its own with any other specialty.

Extracellular calcium chelation and attenuation of calcium entry decrease in vivo cholinergic-induced eccrine sweating sensitivity in humans

NEW FINDINGS

What is the central question of this study? Calcium is an important second messenger in eccrine sweating; however, whether modulation of extracellular Ca(2+) and Ca(2+) entry has the capacity to modulate sweat rate in non-glabrous human skin has not been explored. What is the main finding and its importance? Acetylcholine to sweat rate dose-response relationships identify that local in vivo Ca(2+) chelation and L-type Ca(2+) channel antagonism have the capacity to attenuate the cholinergic sensitivity of eccrine sweat glands. Importantly, these data translate previous glabrous in vitro animal studies into non-glabrous in vivo human skin. Calcium is an important second messenger in eccrine sweating, with both internal and external sources being identified in vitro. It is unclear whether in vivo modulation of extracellular Ca(2+) levels or influx has the capacity to modulate sweat rate in non-glabrous human skin. To test the hypothesis that lowering interstitial Ca(2+) levels would decrease the sensitivity of the ACh to sweat rate (via capacitance hygrometry) dose-response relationship, nine healthy subjects received six ACh doses (1 × 10(-5) to 1 × 10(0) m in 10-fold increments) with and without a Ca(2+) chelator (12.5 mg ml(-1) EDTA) via forearm intradermal microdialysis (protocol 1). To test the hypothesis that attenuating Ca(2+) influx via L-type Ca(2+) channels would also decrease the sensitivity of the ACh to sweat rate dose-response relationship, 10 healthy subjects received similar ACh doses with and without a phenylalkylamine Ca(2+) channel blocker (1 mm verapamil; protocol 2). Non-linear regression curve fitting identified a right-shifted ED50 in EDTA-treated sites compared with ACh alone (-1.0 ± 0.1 and -1.5 ± 0.1 logm, respectively; P < 0.05), but unchanged maximal sweat rate (0.60 ± 0.07 and 0.58 ± 0.11 mg cm(-2) min(-1), respectively; P > 0.05) in protocol 1. Protocol 2 also resulted in a right-shifted ED(50) (verapamil, -0.9 ± 0.1 logm; ACh alone, -1.6 ± 0.2 logm; P < 0.05), with unchanged maximal sweat rate (verapamil, 0.45 ± 0.08 mg cm(-2) min(-1); ACh alone, 0.35 ± 0.06 mg cm(-2) min(-1); P > 0.05). Thus, local in vivo Ca(2+) chelation and L-type Ca(2+) channel antagonism have the capacity to attenuate in vivo cholinergic sensitivity of eccrine sweat glands. These data suggest that interstitial Ca(2+) and its influx via Ca(2+) channels play a functional role in eccrine sweating in intact non-glabrous human skin.

Therapeutic effectiveness of botulinum toxin type A based on severity of palmar hyperhidrosis

A dose of 60 units (U) of botulinum toxin type A (BT-A) has been confirmed to have efficacy for patients with palmoplantar hyperhidrosis. However, the effectiveness of this dose is limited in severe cases defined as sweat production of 2 mg/cm(2) per min or more (measured by the ventilated capsule method) and a Hyperhidrosis Disease Severity Scale (HDSS) grade of 3 or 4. An increased dose of 90 U of BT-A was found to reduce sweating for approximately 7 months. In a comparison of patients with sweat production of more than 2.5 mg/cm(2) per min and an HDSS grade of 4 and patients with sweat production of 2.5 mg/cm(2) per min or less and an HDSS grade of 3, there was no difference in the reduction of sweat production at 5 months, but the duration of the reduced sweating was shorter for the former group. This suggests that there are limits to the efficacy of BT-A for severe forms of the disease with sweat production of more than 2.5 mg/cm(2) per mL.

Mechanisms and controllers of eccrine sweating in humans

Human body temperature is regulated within a very narrow range. When exposed to hyperthermic conditions, via environmental factors and/or increased metabolism, heat dissipation becomes vital for survival. In humans, the primary mechanism of heat dissipation, particularly when ambient temperature is higher than skin temperature, is evaporative heat loss secondary to sweat secretion from eccrine glands. While the primary controller of sweating is the integration between internal and skin temperatures, a number of non-thermal factors modulate the sweating response. In addition to summarizing the current understanding of the neural pathways from the brain to the sweat gland, as well as responses at the sweat gland, this review will highlight findings pertaining to studies of proposed non-thermal modifiers of sweating, namely, exercise, baroreceptor loading state, and body fluid status. Information from these studies not only provides important insight pertaining to the basic mechanisms of sweating, but also perhaps could be useful towards a greater understanding of potential mechanisms and consequences of disease states as well as aging in altering sweating responses and thus temperature regulation.