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International Immunology Jul 2019The hair follicle (HF) is a complex mini-organ that constantly undergoes dynamic cycles of growth and regression throughout life. While proper progression of the hair... (Review)
Review
The hair follicle (HF) is a complex mini-organ that constantly undergoes dynamic cycles of growth and regression throughout life. While proper progression of the hair cycle requires homeostatic interplay between the HF and its immune microenvironment, specific parts of the HF, such as the bulge throughout the hair cycle and the bulb in the anagen phase, maintain relative immune privilege (IP). When this IP collapses, inflammatory infiltrates that aggregate around the bulge and bulb launch an immune attack on the HF, resulting in hair loss or alopecia. Alopecia areata (AA) and primary cicatricial alopecia (PCA) are two common forms of immune-mediated alopecias, and recent advancements in understanding their disease mechanisms have accelerated the discovery of novel treatments for immune-mediated alopecias, specifically AA. In this review, we highlight the pathomechanisms involved in both AA and CA in hopes that a deeper understanding of their underlying disease pathogenesis will encourage the development of more effective treatments that can target distinct disease pathways with greater specificity while minimizing adverse effects.
Topics: Alopecia; Animals; Hair Follicle; Humans
PubMed: 31050755
DOI: 10.1093/intimm/dxz039 -
Scientific Reports May 2021Since 2013, a high incidence of bilateral symmetrical alopecia has been observed in free-ranging Formosan macaques (Macaca cyclopis) in Mt. Longevity, Taiwan. We...
Since 2013, a high incidence of bilateral symmetrical alopecia has been observed in free-ranging Formosan macaques (Macaca cyclopis) in Mt. Longevity, Taiwan. We hypothesized that stress induces alopecia in this population. To verify our hypothesis, we evaluated the histopathological characteristics of skin biopsy and used a validated enzyme immunoassay (EIA) for fecal glucocorticoid metabolite (FGM) analysis, which act as an indicator of stress experienced by the individual. Follicular densities were lower (2.1-3.0 mm) in individuals with symmetrical alopecia than in those with normal hair conditions (4.7 mm). Furthermore, anagen to catagen/telogen ratios were lower in individuals with alopecia (0-1.4) than in those with normal hair (4.0). The histopathological characteristics of alopecia were similar to those of telogen effluvium, which indicates that stress is one of the possible etiologies. On the basis of the analytical and biological validation of EIAs for FGM analysis, 11β-hydroxyetiocholanolone was considered suitable for monitoring adrenocortical activity in both sexes of Formosan macaques. The mean concentrations (standard error; sample size) of 11β-hydroxyetiocholanolone were 2.02 (0.17; n = 10) and 1.41 (0.10; n = 31) μg/g for individuals with and without alopecia, respectively. Furthermore, the results of logistic regression analysis show that 11β-hydroxyetiocholanolone (p = 0.012) concentration was positively associated with alopecia. Thus, stress was the most likely to trigger symmetrical alopecia in Formosan macaques in Mt. Longevity. Although stress can decrease the fitness of an individual, considering the population status of Formosan macaques in Taiwan is stable and alopecia was only observed in our study area, which is isolated from other populations, the impact on the total population of Formosan macaque in Taiwan is limited. Nonetheless, stress-induced immunosuppression and alopecia might affect the local abundance and increase zoonosis risk due to frequent human-macaque contact in Mt. Longevity. Future studies are suggested to focus on the causative factor of stress and the effects of stress and alopecia on the health and welfare in the Formosan macaques.
Topics: Alopecia; Animals; Feces; Female; Glucocorticoids; Macaca; Male; Skin; Stress, Psychological
PubMed: 34045621
DOI: 10.1038/s41598-021-90725-2 -
Cells & Development Jun 2022Alopecia is a non-specific term for hair loss clinically diagnosed by the hair loss pattern and histological analysis of patient scalp biopsies. The immune-mediated... (Review)
Review
Alopecia is a non-specific term for hair loss clinically diagnosed by the hair loss pattern and histological analysis of patient scalp biopsies. The immune-mediated alopecia subtypes, including alopecia areata, lichen planopilaris, frontal fibrosing alopecia, and central centrifugal cicatricial alopecia, are common, significant forms of alopecia subtypes. For example, alopecia areata is the most common autoimmune disease with a lifetime incidence of approximately 2% of the world's population. In this perspective, we discuss major results from studies of immune-mediated alopecia subtypes. These studies suggest the key event in disease onset as the collapse in immune privilege, which alters the hair follicle microenvironment, e.g., upregulation of major histocompatibility complex molecules and increase of cytokine production, and results in immune cell infiltration, inflammatory responses, and damage of hair follicles. We note that previous studies have established that the hair follicle has a complex mechanical microenvironment, which may regulate the function of not only tissue cells but also immune cell infiltrates. This suggests a potential for mechanobiology to contribute to alopecia research by adding new methods, new approaches, and new ways of thinking, which is missing in the existing literature. To fill this a gap in the alopecia research space, we develop a mechanobiological hypothesis that alterations in the hair follicle microenvironment, specifically in the mechanically responsive tissues and cells, partially due to loss of immune privilege, may be contributors to disease pathology. We further focus our discussion on the potential for applying mechanoimmunology to the study of T cell infiltrates in the hair follicle, as they are considered primary contributors to alopecia pathology. To establish the connection between the mechanoimmunological hypothesis and immune-mediated alopecia subtypes, we discuss what is known about the role of T cells in immune-mediated alopecia subtypes, using the most extensively studied AA as our model.
Topics: Alopecia Areata; Biophysics; Hair Follicle; Humans; Lichen Planus
PubMed: 35649504
DOI: 10.1016/j.cdev.2022.203793 -
Dermatology Online Journal Aug 2012Cutaneous sarcoidosis of the scalp may induce scarring alopecia, which clinically resembles other forms of primary cicatricial alopecia. Differentiation via histologic... (Review)
Review
Cutaneous sarcoidosis of the scalp may induce scarring alopecia, which clinically resembles other forms of primary cicatricial alopecia. Differentiation via histologic evaluation is necessary because sarcoidosis demonstrates classical non-caseating granulomas. Review of the literature reveals that sarcoidosis-induced alopecia occurs more commonly in black females age 23 to 78, with the majority of patients having coexisting facial sarcoidosis with pulmonary and lymph node involvement. Given the strong association between sarcoidal alopecia and systemic sarcoidosis, evaluation of the patient is indicated if alopecia is the initial presenting manifestation.
Topics: Black or African American; Alopecia; Cicatrix; Female; Humans; Male; Middle Aged; Sarcoidosis; Scalp; Sex Factors
PubMed: 22948054
DOI: No ID Found -
Journal of the American Academy of... Feb 2022The current classification for alopecia areata (AA) does not provide a consistent assessment of disease severity.
BACKGROUND
The current classification for alopecia areata (AA) does not provide a consistent assessment of disease severity.
OBJECTIVE
To develop an AA severity scale based on expert experience.
METHODS
A modified Delphi process was utilized. An advisory group of 22 AA clinical experts from the United States was formed to develop this AA scale. Representatives from the pharmaceutical industry provided feedback during its development.
RESULTS
Survey responses were used to draft severity criteria, aspiring to develop a simple scale that may be easily applied in clinical practice. A consensus vote was held to determine the final AA severity statement, with all AA experts agreeing to adopt the proposed scale.
LIMITATIONS
The scale is a static assessment intended to be used in clinical practice and not clinical trials.
CONCLUSION
The final AA disease severity scale, anchored in the extent of hair loss, captures key features commonly used by AA experts in clinical practice. This scale will better aid clinicians in appropriately assessing severity in patients with this common disease.
Topics: Alopecia; Alopecia Areata; Consensus; Humans; Severity of Illness Index
PubMed: 34474079
DOI: 10.1016/j.jaad.2021.08.043 -
American Family Physician Mar 2003Alopecia can be divided into disorders in which the hair follicle is normal but the cycling of hair growth is abnormal and disorders in which the hair follicle is... (Review)
Review
Alopecia can be divided into disorders in which the hair follicle is normal but the cycling of hair growth is abnormal and disorders in which the hair follicle is damaged. Androgenetic alopecia is the most common cause of hair loss in women. Other disorders include alopecia areata, telogen effluvium, cicatricial alopecia, and traumatic alopecias. The diagnosis is usually based on a thorough history and a focused physical examination. In some patients, selected laboratory tests or punch biopsy may be necessary. Topically administered minoxidil is labeled for the treatment of androgenetic alopecia in women. Corticosteroids and other agents are typically used in women with alopecia areata. Telogen effluvium is often a self-limited disorder. Because alopecia can be devastating to women, management should include an assessment for psychologic effects.
Topics: Administration, Topical; Alopecia Areata; Female; Glucocorticoids; Humans; Injections, Intralesional; Minoxidil; Triamcinolone Acetonide
PubMed: 12643360
DOI: No ID Found -
Anais Brasileiros de Dermatologia 2016The transforming growth factor-beta 1 (TGFβ1) promotes fibrosis, differentiating epithelial cells and quiescent fibroblasts into myofibroblasts and increasing... (Review)
Review
The transforming growth factor-beta 1 (TGFβ1) promotes fibrosis, differentiating epithelial cells and quiescent fibroblasts into myofibroblasts and increasing expression of extracellular matrix. Recent investigations have shown that PPAR (peroxisome proliferator-activated receptor*) is a negative regulator of fibrotic events induced by TGFβ1. Dehydroepiandrosterone (DHEA) is an immunomodulatory hormone essential for PPAR functions, and is reduced in some processes characterized by fibrosis. Although scarring alopecia characteristically develops in the female biological period in which occurs decreased production of DHEA, there are no data in the literature relating its reduction to fibrogenic process of this condition. This article aims to review the fibrogenic activity of TGFβ1, its control by PPAR and its relation with DHEA in the frontal fibrosing alopecia.
Topics: Alopecia; Dehydroepiandrosterone; Female; Fibroblasts; Fibrosis; Humans; Lichen Planus; PPAR gamma; Transforming Growth Factor beta1
PubMed: 28099600
DOI: 10.1590/abd1806-4841.20165029 -
Acta Dermato-venereologica Aug 2022
Topics: Alopecia; Humans; Hypohidrosis; Nail Diseases; Nails, Malformed; Propylthiouracil
PubMed: 35971830
DOI: 10.2340/actadv.v102.2690 -
Indian Journal of Dermatology,... 2023The Janus kinase (JAK) and Signal Transducer and Activator of Transcription (STAT) pathway has been identified as a key player in the pathophysiology of alopecia areata... (Review)
Review
The Janus kinase (JAK) and Signal Transducer and Activator of Transcription (STAT) pathway has been identified as a key player in the pathophysiology of alopecia areata and a potential target for therapy. Here, we give a narrative review of what is known about Janus kinase inhibitors in alopecia areata. Several clinical trials as well as smaller studies have demonstrated hair regrowth and remission with oral Janus kinase inhibitors therapy, even in patients who failed conventional treatment. Baricitinib is the only US FDA-approved treatment for alopecia areata but data for other oral Janus kinase inhibitors such as tofacitinib, ruxolitinib and ritlecitinib are also promising. Fewer clinical trials have investigated topical Janus kinase inhibitors for alopecia areata, with many of them terminated early due to unfavourable results. Overall, Janus kinase inhibitors are an efficacious addition to the therapeutic arsenal for treatment-refractory alopecia areata. Further work is needed to examine the effects of long-term usage of Janus kinase inhibitors, the efficacy of topical Janus kinase inhibitors, as well as to identify biomarkers that could predict differential therapeutic responses to the various Janus kinase inhibitors.
Topics: Humans; Alopecia Areata; Janus Kinase Inhibitors; Alopecia; Hair; Janus Kinases
PubMed: 37436019
DOI: 10.25259/IJDVL_1093_2022 -
The Oncologist Jan 2018Chemotherapy-induced alopecia (CIA) is the most visibly distressing side effect of commonly administered chemotherapeutic agents. Because psychological health has huge... (Review)
Review
UNLABELLED
Chemotherapy-induced alopecia (CIA) is the most visibly distressing side effect of commonly administered chemotherapeutic agents. Because psychological health has huge relevance to lifestyle, diet, and self-esteem, it is important for clinicians to fully appreciate the psychological burden that CIA can place on patients. Here, for the first time to our knowledge, we provide a comprehensive review encompassing the molecular characteristics of the human hair follicle (HF), how different anticancer agents damage the HF to cause CIA, and subsequent HF pathophysiology, and we assess known and emerging prevention modalities that have aimed to reduce or prevent CIA. We argue that, at present, scalp cooling is the only safe and U.S. Food and Drug Administration-cleared modality available, and we highlight the extensive available clinical and experimental (biological) evidence for its efficacy. The likelihood of a patient that uses scalp cooling during chemotherapy maintaining enough hair to not require a wig is approximately 50%. This is despite different types of chemotherapy regimens, patient-specific differences, and possible lack of staff experience in effectively delivering scalp cooling. The increased use of scalp cooling and an understanding of how to deliver it most effectively to patients has enormous potential to ease the psychological burden of CIA, until other, more efficacious, equally safe treatments become available.
IMPLICATIONS FOR PRACTICE
Chemotherapy-induced alopecia (CIA) represents perhaps the most distressing side effect of chemotherapeutic agents and is of huge concern to the majority of patients. Scalp cooling is currently the only safe option to combat CIA. Clinical and biological evidence suggests improvements can be made, including efficacy in delivering adequately low temperature to the scalp and patient-specific cap design. The increased use of scalp cooling, an understanding of how to deliver it most effectively, and biological evidence-based approaches to improve its efficacy have enormous potential to ease the psychological burden of CIA, as this could lead to improvements in treatment and patient quality-of-life.
Topics: Alopecia; Antineoplastic Agents; Humans; Hypothermia, Induced; Neoplasms; Prognosis
PubMed: 28951499
DOI: 10.1634/theoncologist.2017-0263