Possible involvement of neuropeptidergic sensory nerves in alopecia areata

Role of neurogenic inflammation in the pathogenesis of alopecia areata

Alopecia areata refers to an autoimmune illness indicated by persistent inflammation. The key requirement for alopecia areata occurrence is the disruption of immune-privileged regions within the hair follicles. Recent research has indicated that neuropeptides play a role in the damage to hair follicles by triggering neurogenic inflammation, stimulating mast cells ambient the follicles, and promoting apoptotic processes in keratinocytes. However, the exact pathogenesis of alopecia areata requires further investigation. Recently, there has been an increasing focus on understanding the mechanisms of immune diseases resulting from the interplay between the nervous and the immune system. Neurogenic inflammation due to neuroimmune disorders of the skin system may disrupt the inflammatory microenvironment of the hair follicle, which plays a crucial part in the progression of alopecia areata.

Adverse event reporting of four anti-Calcitonin gene-related peptide monoclonal antibodies for migraine prevention: a real-world study based on the FDA adverse event reporting system

Background: Anti-Calcitonin gene-related peptide monoclonal antibodies (anti-CGRP mAbs) have shown significant efficacy in preventing migraine. However, there have been limited reports of adverse events (AEs) after marketing, particularly for eptinezumab launched in 2020. The study aimed to mine and analyze the AE signals with four anti-CGRP mAbs from the United States Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database to gain insights into the safety profile of these medications post-marketing. Methods: All AE reports on the four anti-CGRP mAbs (erenumab, galcanezumab, fremanezumab, and eptinezumab) were retrieved from the FAERS database from the first quarter (Q1) of 2018 to Q1 of 2023. Disproportionality analysis was measured by reporting odd ratio (ROR) and Bayesian confidence propagation neural network (BCPNN) to identify potential AE signals. Comparisons were made between the four drugs in terms of AEs. Results: A total of 38,515 reports of erenumab, 19,485 reports of galcanezumab, 5,332 reports of fremanezumab, and 2,460 reports of eptinezumab were obtained, mostly reported in the second to third year after launch in the market. The common AEs to erenumab included constipation (17.93%), injection site pain (14.08%), and alopecia (7.23%). The AEs that occurred more frequently with galcanezumab included injection site pain (24.37%), injection site erythema (5.35%), and injection site haemorrhage (4.97%). Common AEs related to fremanezumab were injection site pain (13.10%), injection site erythema (7.02%), and injection site pruritus (5.47%). Fatigue (13.54%), throat irritation (9.02%), and pruritus (8.20%) were the most common AEs with eptinezumab. In addition, there are new AEs that were not listed in the drug instructions but occurred concurrently with multiple drugs, such as Raynaud's phenomenon, weight increase, menstrual disorders, throat tightness, and paraesthesia oral. Conclusion: Common AE signals of the four anti-CGRP mAbs and new AE signals were found to provide a reference for clinical drug selection in clinical practice.

Alopecia as an emerging adverse event to CGRP monoclonal antibodies: Cases Series, evaluation of FAERS, and literature review

BACKGROUND

Alopecia is associated with erenumab post-marketing, but no cases have been described.

METHODS

We describe two patients that reported temporary hair loss and review the FDA Adverse Event Reporting System (FAERS).

RESULTS

The first patient experienced alopecia within three months of starting erenumab, which did not improve with ongoing use or transition to fremanezumab. The second patient reported alopecia within two weeks of starting erenumab, which continued after transition to galcanezumab; months later, there was also recurrent hair loss within one month of starting fremanzeumab. According to FAERS (last accessed 18 August 2022), alopecia was reported most with erenumab (1158), followed by galcanezumab (554), fremanezumab (175), eptinezumab (23), rimegepant (26), ubrogepant (4), and atogepant (3).

CONCLUSION

Most events were reported in women and non-serious. The potential mechanism of alopecia with drugs targeting calcitonin gene-related peptide or its receptor possibly includes disruptions in the microvascular circulation and other homeostatic mechanisms.

New Insight on the Safety of Erenumab: An Analysis of Spontaneous Reports of Adverse Events Recorded in the US Food and Drug Administration Adverse Event Reporting System Database

AIM

The aim of this article was to provide an overview of adverse events reported for erenumab in post-marketing through the Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) and perform a disproportionality analysis with other drugs used for acute or preventative treatment of migraine as controls.

METHODS

FAERS was screened from the first quarter of 2018 to the second quarter of 2020 (latest data update 30 June 2020). Clinical and demographic characteristics of cases were described along with the seriousness and outcome of adverse events. Disproportionality analyses were performed using the reporting odds ratio (ROR).

RESULTS

In total, 23,312 cases were reported during the study period, 67.0% by consumers. Cases in the age range 18-64 years (10,922 cases; 45.8%), in female sex (15,099 cases; 64.8%), and with adverse events that were classified as non-serious (19,626 cases; 84.2%) were the most prevalent in the database. After the exclusion of duplicates, 146 fatal cases were identified. A total of 1303 unlabeled adverse events were reported, of which 49 had statistically significant disproportionality of reporting in comparison with other drugs used for acute or preventative treatment of migraine. Identified disproportionality signals included alopecia, depression, anxiety, myocardial infarction, increased heart rate, pulmonary embolism, weight alteration, insomnia, tinnitus, and influenza-like symptoms. Injection-site reactions (labeled events) were co-reported with errors in administration procedures.

CONCLUSION

Adverse events reported during the first 2 years of post-marketing surveillance were mostly non-serious and with a favorable prognosis. However, new safety aspects emerged for which further studies are needed to confirm the associations, prioritizing unlabeled events with consistent disproportionality signals (e.g., emerging in at least 4 out of 6 analyses).

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.

Are Preferred Scalp Locations for Alopecia Areata Patches a Clue to Neuronal Etiology?

Background

Alopecia areata (AA) is an autoimmune disease causing hair loss in 2% of the population. Anecdotally, hair specialists report that patches localize to the scalp periphery. Changes in sensory innervation and/or scalp vasculature may play a role in the development and localization of alopecic patches.

Objective

To evaluate the most common locations of initial alopecic scalp patches.

Materials and Methods

A retrospective chart review, with comprehensive evaluation of clinical photographs, was conducted from July 2016 to June 2018 to include AA patients (n = 112). Clinical data was collected on gender, age, race, time until presentation at the clinic, and areas of hair loss on initial presentation.

Results

The most common areas of initial AA patches in both females and males were the occiput (49 vs. 48.5%), parietal (46.9 vs. 21.2%), vertex (26.5 vs. 18.2%), and frontal (24.5 vs. 18.2%) regions; 26.8% of patients present with either alopecia totalis or universalis.

Limitations

This is a single-center study with underrepresentation of minority races.

Conclusion

AA patches most commonly present on the occiput of the scalp in both female and male patients. Cervical spine nerves C3 and C2 supply sensory innervation and the occipital artery supplies blood to this area.

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.

The role of capsaicin in dermatology

Neurogenic pain and pruritus are the common chief complaints at dermatology office visits. Unfortunately, they are also notoriously difficult conditions to treat. Topical capsaicin used as a single therapy or as an adjuvant offers a low-risk option for patients who do not achieve control on other therapies. This chapter presents the evidence behind topical capsaicin use in dermatologic conditions characterized by neurogenic pain or pruritus, including postherpetic neuralgia, notalgia paresthetica, brachioradial pruritus, lichen simplex chronicus, prurigo nodularis, pruritus ani, pruritus of hemodialysis, aquagenic pruritus, apocrine chromhidrosis, lipodermatosclerosis, alopecia areata, and psoriasis. It presents the most common capsaicin formulations, dosages, and durations of treatment for each condition. Additionally, the chapter addresses various adverse effects and limitations in the use of topical capsaicin in dermatology.

Immunohistochemical comparison of whisker pad cutaneous innervation in Swiss Webster and hairless mice

To establish the mouse mutant, hairless (Hr), as a useful model for future analyses of target-ending interactions, we assessed the cutaneous innervation in the whisker pad after loss of primary hair targets. Postnatal (P) development of fur in Hr begins similarly to that of "normal" Swiss Webster (SW) mice. Around P10, hairs are shed and the follicles rendered permanently incompetent. Hair loss progresses rostrocaudally until the entire skin is denuded. Substantial alterations in the distribution and density of sensory and autonomic endings in the mystacial pad vibrissal and intervibrissal fur innervation were discovered. Pilo-neural complexes innervating fur hairs were dismantled in Hr. Epidermal innervation in SW was rich; only a few endings expressed growth-associated protein-43 kdal (GAP), suggesting limited changes in axonal elongation. Innervation in Hr formed a dense layer passing upward through the thickened epidermis, with substantial increases among all types of endings. Vibrissal follicle-sinus complexes were also hyperinnervated. Endings in Hr vibrissae and fur were strongly GAP-positive, suggesting reorganization of innervation. Dermal and vascular autonomic innervation in both strains co-localized tyrosine hydroxylase and neuropeptide Y, but only in Hr did neuropeptide Y co-localize calcitonin gene-related peptide (CGRP) and express GAP immunolabeling. Stereological quantitation of trigeminal ganglia revealed no differences in neuron number between Hr and SW, although there were small increases in cell volume in Hr trigeminal ganglion cells. These results suggested that a form of collateral sprouting was active in Hr mystacial pads, not in response to local injury, but as a result of loss of primary target tissues.

Topical capsaicin. The fire of a 'hot' medicine is reignited

IMPORTANCE OF THE FIELD

Capsaicin and its receptor, TRPV1, occupy a central place in current neurophysiological studies regarding pain transmission and have opened new avenues for understanding the role of transient receptor potential (TRP) receptors in itch processing. Substantial efforts in drug discovery are at present directed at vanilloid receptors for finding new remedies for pain and itch.

AREAS COVERED IN THIS REVIEW

We provide an overview of the major clinical indications of capsaicin, primarily targeting pain and itch of various origins, with an emphasis on the usefulness of capsaicin in treating pruritus and dermatological conditions. In particular, we cover the most relevant findings in recent years, from 2000 onward (although seminal discoveries and studies are discussed irrespective of their date of publication if deemed essential for understanding capsaicin's actions).

WHAT THE READER WILL GAIN

Readers are offered a broad perspective on the areas of clinical application of capsaicin, emphasizing its usefulness in the treatment of neurophatic pain and pruritus of various origins.

TAKE HOME MESSAGE

Capsaicin has been proven a truly exciting molecule and remains a valuable drug for alleviating pain and itch, widely surpassing its role as a simple spicy ingredient.

Development of alopecia areata is associated with higher central and peripheral hypothalamic-pituitary-adrenal tone in the skin graft induced C3H/HeJ mouse model

The relationship of the stress response to the pathogenesis of alopecia areata (AA) was investigated by subjecting normal and skin graft-induced, AA-affected C3H/HeJ mice to light ether anesthesia or restraint stress. Plasma corticosterone (CORT), adrenocorticotropic hormone (ACTH), and estradiol (E2) levels were determined by RIA, whereas gene expression in brains, lymphoid organs, and skin was measured by quantitative RT-PCR for corticotropin-releasing hormone (Crh), arginine vasopressin (Avp), proopiomelanocortin (Pomc), glucocorticoid receptor (Nr3c1), mineralocorticoid receptor (Nr3c2), corticotropin-releasing hormone receptor types 1 and 2 (Crhr1, Crhr2), interleukin-12 (Il12), tumor necrosis factor-alpha (Tnf alpha), and estrogen receptors type-1 (Esr1) and type-2 (Esr2). AA mice had a marked increase in hypothalamic-pituitary-adrenal (HPA) tone and activity centrally, and peripherally in the skin and lymph nodes. There was also altered interaction between the adrenal and gonadal axes compared with that in normal mice. Stress further exacerbated changes in AA mouse HPA activity both centrally and peripherally. AA mice had significantly blunted CORT and ACTH responses to acute ether stress (physiological stressor) and a deficit in habituation to repeated restraint stress (psychological stressor). The positive correlation of HPA hormone levels with skin Th1 cytokines suggests that altered HPA activity may occur as a consequence of the immune response associated with AA.

Neuronal plasticity of the “brain–skin connection”: stress-triggered up-regulation of neuropeptides in dorsal root ganglia and skin via nerve growth factor-dependent pathways

Emerging research indicates that central-nervous stress perception is translated to peripheral tissues such as the skin not only via classical stress hormones but also via neurotrophins and neuropeptides. This can result in neurogenic inflammation, which is likely to contribute to the triggering and/aggravation of immunodermatoses. Although the existence of such a "brain-skin connection" is supported by steadily increasing experimental evidence, it remains unclear to which extent perceived stress affects the sensory "hardwiring" between skin and its afferent neurons in the corresponding dorsal root ganglia (DRG). In this paper, we provide experimental evidence in a murine model of stress (exposure of C57BL/6 mice to sound stress) that stress exposure, or intracutaneous injection of recombinant nerve growth factor (NGF) to mimic the skin's response to stress, up-regulate the percentage of substance P (SP)+ or calcitonin gene-related peptide (CGRP)+ sensory neurons in skin-innervating DRG. Further, we show that the number of SP+ or CGRP+ sensory nerve fibers in the dermis of stressed C57BL/6 mice is significantly increased. Finally, we document that neutralization of NGF activity abrogates stress-induced effects on the percentage of SP+ and CGRP+ sensory neurons in skin-innervating DRG as well as on dermal sensory nerve fibers. These data suggest that high stress perception results in an intense cross talk between the skin and skin-innervating DRG, which increases the likelihood of NGF-dependent neurogenic skin inflammation by enhancing sensory skin innervation.

Adrenomedullin is induced by hypoxia and enhances pancreatic cancer cell invasion

Adrenomedullin (ADM) is synthesized by different types of cells and acts by binding calcitonin receptor-like receptor (CRLR) and members of the receptor activity-modifying protein (RAMP) family. In this study, the expression and functional role of ADM and its signaling components were investigated in pancreatic adenocarcinoma (PDAC). By QRT-PCR, median mRNA levels of ADM and CRLR were 1.5- and 2.4-fold higher, respectively, in PDAC tissues compared to normal pancreatic tissues. By immunohistochemistry, ADM, CRLR, RAMP1 and RAMP2, but not RAMP3, were expressed in pancreatic cancer cells. ADM serum levels were significantly increased in PDAC patients compared to healthy controls and chronic pancreatitis (CP) patients, with an area under the ROC curve of 0.83 and 0.98, respectively. At a cut-off level of 30.6 ng/ml, the specificity of ADM to differentiate PDAC from controls and CP patients was 85.5 and 83.6%, with a sensitivity of 80 and 100%. All 5 evaluated pancreatic cancer cells lines expressed ADM, CRLR, RAMP1 and RAMP2, whereas RAMP3 was expressed in only 1/5 pancreatic cancer cell lines. ADM was strongly induced by hypoxia and significantly increased invasiveness in 3/5 human pancreatic cancer cells. Blocking of CRLR decreased invasiveness in 4/5 human pancreatic cancer cells. In addition, rADM slightly up-regulated vascular endothelial growth factor secretion in 3/5 cell lines. In conclusion, ADM is induced by hypoxia and over-expressed in PDAC and might therefore serve as a potential tumor marker. Furthermore, ADM increases invasiveness of some pancreatic cancer cells and might influence angiogenesis, suggesting that blocking this pathway might have a therapeutic potential.

Substance P as an Immunomodulatory Neuropeptide in a Mouse Model for Autoimmune Hair Loss (Alopecia Areata)

Alopecia areata (AA) is an autoimmune disorder of the hair follicle characterized by inflammatory cell infiltrates around actively growing (anagen) hair follicles. Substance P (SP) plays a critical role in the cutaneous neuroimmune network and influences immune cell functions through the neurokinin-1 receptor (NK-1R). To better understand the role of SP as an immunomodulatory neuropeptide in AA, we studied its expression and effects on immune cells in a C3H/HeJ mouse model for AA. During early stages of AA development, the number of SP-immunoreactive nerve fibers in skin is increased, compared to non-affected mice. However, during advanced stages of AA, the number of SP-immunoreactive nerves and SP protein levels in skin are decreased, whereas the expression of the SP-degrading enzyme neutral endopeptidase (NEP) is increased, compared to control skin. In AA, NK-1R is expressed on CD8+ lymphocytes and macrophages accumulating around affected hair follicles. Additional SP supply to the skin of AA-affected mice leads to a significant increase of mast cell degranulation and to accelerated hair follicle regression (catagen), accompanied by an increase of CD8+ cells-expressing granzyme B. These data suggest that SP, NEP, and NK-1R serve as important regulators in the molecular signaling network modulating inflammatory response in autoimmune hair loss.

Clues from Alopecia Areata on the Role of Neuropeptides in the Initiation of Autoimmunity

A fascinating question regarding the pathogenesis of alopecia areata is the potential linkage with the brain. Siebenharr et al. demonstrate that substance P fibers are increased in early lesions, and that substance P treatment induces catagen follicles along with activated CD8+ T cells. Potentially, neuropeptides serve as the initial insult resulting in loss of tolerance and autoimmune disease.

Expression of neuropeptide-degrading enzymes in alopecia areata: an immunohistochemical study

BACKGROUND

Much clinical evidence suggests that the nervous system, including psychological factors, can influence the course of alopecia areata (AA). However, there has been little substantial evidence of specific participation of cutaneous neurogenic factors in the disease process.

OBJECTIVES

As previous studies have demonstrated that stress elicits the release of the neuropeptide substance P (SP) from peripheral nerves and that some patients with AA show prominent SP expression in nerves surrounding their hair follicles, we aimed to evaluate the role of SP in AA.

METHODS

We used immunohistochemistry to examine the expression of SP and SP-degrading enzymes in scalp biopsies from patients with AA and from healthy controls.

RESULTS

Affected hair follicles in the centre of the areas of hair loss of patients with AA were richly innervated by SP-staining nerve fibres. Strong expression of the SP-degrading enzyme, neutral endopeptidase (NEP), was observed in hair follicles not only in the acute progressive phase of AA but also in the chronic stable phase. Expression of NEP in hair follicles from the margins of areas of hair loss was stronger than in normal controls, but was weaker than in the centre of the areas of hair loss. In addition, endothelial immunoreactivity for angiotensin-converting enzyme (also capable of degrading SP) was not observed in the centre of the areas of hair loss, which was in significant contrast to normal controls as well as to the margins of areas of hair loss where it was expressed. Further, intense expression of endothelial leucocyte adhesion molecule-1 on vessels and many degranulating mast cells was observed adjacent to affected hair follicles in AA, in admixture with dense lymphocytic inflammation.

CONCLUSIONS

These findings suggest that SP is endogenously released by dermal nerve fibres around hair follicles and that it may play an important part in epithelial-mesenchymal-neuroectodermal interactions in AA. This study reveals that SP and its degrading enzymes are involved in the pathogenesis of AA, which in turn might explain the pathological significance of neurogenic and psychogenic aspects in the disease process.