Mechanisms of tolerance and potential therapeutic interventions in Alopecia Areata

Causal role of immune cells in alopecia areata: A two-sample Mendelian randomization study

BACKGROUND

Previous research has highlighted an association between alopecia areata (AA) and the collapse of hair follicle immune privilege, however, the causal linkage to specific immune cell traits remains to be elucidated. This study aimed to investigate the causal influence of immune cell traits on AA utilizing a two-sample Mendelian randomization (MR) approach.

METHODS

Leveraging GWAS summary statistics of 731 immunological traits (n = 3757) and AA data (n = 211,428), MR analyses were conducted employing inverse-variance weighted (IVW), weighted median, and MR-Egger regression methodologies. Sensitivity analyses were undertaken using Cochran's Q test, MR-Egger intercept test, and MR-PRESSO analysis. A reverse MR analysis was performed for immune cell traits identified in the initial MR analysis.

RESULTS

Our study unveiled multiple immune traits associated with AA. Protective associations were observed for CD62L- CD86+ myeloid dendritic cells (DCs), TD CD4+%CD4+ T cells, and others, with ORs ranging from 0.63 to 0.78. Conversely, traits like CD62L on CD62L+ plasmacytoid DCs, HLA-DR on CD14- CD16+ monocytes, HLA-DR on monocytes, and others, were determined to augment the risk of AA, with ORs ranging from 1.13 to 1.46. Reverse MR analysis signified a reduction in BAFF-R on IgD-CD24-B cells post-AA onset (OR: 0.97, 95% CI: 0.95-1.00), with no identified heterogeneity or horizontal pleiotropy among the instrumental variables (IVs).

CONCLUSIONS

Our findings suggests that CD62L on certain subpopulations of DCs and HLA-DR on monocytes may epitomize risk factors for AA, offering potential therapeutic targets for alleviating AA.

Gut microbiome, metabolome and alopecia areata

Alopecia areata (AA) is a type of dermatological disease characterized by rapid and non-scarring hair loss of the scalp or body skin that may be related to genetic, immunological and physiological factors. It is now believed that AA is associated with oxidative stress, autoimmune disease, neuropsychological factors, pathogens, immune checkpoint inhibitors and microecological imbalance under the premise of host genetic susceptibility. In recent years, studies have revealed the significant role of the gut microbiome or metabolome in many aspects of human health. Diverse studies have revealed that the gut microbiome and metabolome have an important influence on skin conditions. This review highlights the relationship between AA and the gut microbiome or metabolome to provide novel directions for the prevention, clinical diagnosis and treatment of AA.

Alopecia Areata: Burden of Disease, Approach to Treatment, and Current Unmet Needs

Alopecia areata is an autoimmune hair loss disorder with variations in distribution, duration, and severity. The disease is chronic and often follows an unpredictable course, frequently leading to stress and anxiety for those who suffer from it. Throughout the years more knowledge has been gained regarding pathogenesis, diagnostic tools, impact on quality of life, as well as treatment strategies for alopecia areata. However, challenges in treating and alleviating the burden of disease remain. In this article, we discuss updates regarding the pathogenesis and treatment of alopecia areata and highlight unmet needs of the condition, including a review of limitations of current treatments, accessibility to management strategies, and the need for disease awareness and advocacy.

Surgical Removal of a Thymoma without Myasthenia Gravis Can Have a Therapeutic Effect on Concurrent Alopecia Areata: A Case Report

Alopecia areata is a chronic organ-specific autoimmune disease and it could be associated with other autoimmune diseases. We, herein, report a case of alopecia areata in a patient with a thymoma without myasthenia gravis. Multiple hairless patches rapidly developed 6 weeks before the first visit on the patient who had been newly diagnosed with thymoma 2 weeks before the hairless patches occurred, and thymectomy was done 2 weeks before visiting dermatologic department. She had no symptoms associated with myasthenia gravis, and there were no abnormal findings on neurologic exams and acetylcholine receptor autoantibody was not detected in serum. Scalp biopsy showed numerous lymphocytic inflammations around hair follicles and in immunohistochemical staining, the aggregation of CD4+ and CD8+ T cells was observed around hair follicles and FoxP3+ T lymphocytes were rarely observed around hair follicles. The patient refused any treatment and her hairless patches were completely recovered 3 months after thymectomy, without being recurred 3 years after thymectomy. On the basis of both clinical manifestations and histologic findings, we concluded that alopecia areata in the patient had developed in association with thymoma and was recovered rapidly after thymectomy.

Validation of the Alopecia Areata Patient Priority Outcomes (AAPPO) Questionnaire in Adults and Adolescents with Alopecia Areata

Introduction

Individuals with alopecia areata (AA) may experience significant impacts on their health-related quality of life. The novel Alopecia Areata Patient Priority Outcomes (AAPPO) questionnaire has been developed to assess hair loss signs, emotional symptoms, and activity limitations associated with AA. The objective of this study was to evaluate psychometric properties and establish scoring of the AAPPO in adults and adolescents with AA.

Methods

Scoring and measurement properties of the AAPPO were examined using baseline and 2-week follow-up data from a prospective, noninterventional, web-based study of 121 patients with AA (85 adults aged ≥ 18 years, 36 adolescents aged 12–17 years) with Severity of Alopecia Tool (SALT) ≥ 25% scalp hair loss.

Results

Exploratory and confirmatory factor analysis supported four single Hair Loss (HL) items, an Emotional Symptoms domain (ES; 4 items), and an Activity Limitations domain (AL; 3 items). Among all patients, the multi-item ES and AL domains had strong internal consistency (α ≥ 0.87); all HL items and domain scores had strong test-retest reliability (weighted kappa or intraclass correlation coefficients ≥ 0.78). All HL item scores demonstrated strong construct validity (r ≥ 0.52) compared with the patient-reported Alopecia Areata Symptom and Impact Scale (AASIS) hair loss subscale score; ES and AL domain scores exhibited strong construct validity (r ≥ 0.66) compared with the SF-36 Mental Component Summary (MCS) score. Using SALT scores, HL mean item scores were better (lower) in the 25–49% SALT subgroup versus those with highest SALT scores (76–100%); however, ES mean domain scores were better in the SALT 76–100% subgroup in the same comparison (p < 0.0001). Using AASIS and MCS score–created subgroups, ES and AL mean domain scores demonstrated hypothesized differences across subgroups (all p values < 0.0001).

Conclusion

The AAPPO questionnaire is a reliable, valid disease-specific measure of hair loss severity and impact in individuals with AA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-021-00648-z.

Reversal of alopecia areata, osteoporosis follow treatment with activation of Tgr5 in mice

BACKGROUND

Alopecia areata is an autoimmune hair loss disease with infiltration of pro-inflammatory cells into hair follicles. The role of Tgr5 in dermatitis has attracted considerable attention. The present study aimed to investigate the effect of Tgr5 in the development of Alopecia areata.

METHODS

The study utilized a comparison control group design with four groups of wild-type group, wild-type+INT777 group, Tgr5-/- group, and Tgr5-/-+INT777 group. The mice were treated with INT777 (30 mg/kg/day) or the carrier solution (DMSO) intraperitoneally for 7 weeks, and the back skin was collected and analyzed by histology and immunohistochemistry staining. The lumbar vertebrae 4 has also been analyzed by DXA and Micro-CT.

RESULTS

Tgr5-/- mice displayed the decreasingly significant in hair area and length, skin thickness, and the ratio of anagen and telogen, collagen, and mast cell number and loss the bone mass than WT group. After treating with INT777, the appearance of alopecia areata and bone microstructure has improved. Immunohistochemistry and qPCR analysis showed that activation of Tgr5 can down-regulate the express of JAK1, STAT3, IL-6, TNF-α, and VEGF.

CONCLUSION

These findings indicate that activation of Tgr5 mediated amelioration of alopecia areata and osteoporosis by down-regulated JAK1-STAT3 signaling pathway.

Development of the Alopecia Areata Patient Priority Outcomes Instrument: A Qualitative Study

INTRODUCTION

Although alopecia areata (AA) profoundly impacts patients' physical appearance, emotional state, and daily activities, no treatment approved for AA currently exists. Patient-reported outcome (PRO) instruments currently used to capture patients' AA experiences do not meet the requirements to support claims of treatment benefit as described in the US Food and Drug Administration's 2009 PRO guidance. Our objective was to explore the consequences and priority treatment outcomes among individuals with AA and develop a PRO measure consistent with regulatory requirements that assesses these priorities and represents clinical benefit from the AA patient perspective.

METHODS

Targeted literature and instrument reviews informed an initial concept set. Concept elicitation interviews with 20 adults with AA confirmed the relevance and importance of the initial concepts, identified additional relevant concepts, and informed an AA consequence model. Thematic analysis yielded a draft item pool, which was evaluated through two iterative rounds of cognitive debriefing interviews with 16 patients with AA (9 adults; 7 adolescents).

RESULTS

Hair loss was the primary consequence of importance to patients with AA. Patients emphasized the need to differentiate hair loss by location: scalp, eyebrows, eyelashes, and body. Consequences of AA include difficulty conducting daily activities, particularly outdoor activities and exercise, and emotional impacts such as sadness, frustration, and negative self-image. Following cognitive debriefing interviews, 11 items were included to form the Alopecia Areata Patient Priority Outcome (AAPPO), assessing AA-related symptoms and impacts over the past week.

CONCLUSIONS

The AAPPO is a novel, content-valid PRO that captures the consequences of AA of the highest priority to patients.

Hair regrowth following fecal microbiota transplantation in an elderly patient with alopecia areata: A case report and review of the literature

BACKGROUND

Alopecia areata is a hair loss disease associated with genetics, autoimmunity, and other factors. There is an intriguing link between alopecia areata and gut dysbiosis. Fecal microbiota transplantation (FMT) has been recommended to treat Clostridium difficile (previously known as Clostridioides difficile) infection, and has also shown potentials in the treatment of inflammatory bowel disease, irritable bowel syndrome, and non-alcohol fatty liver disease.

CASE SUMMARY

An 86-year-old man, with a history of sigmoid colon carcinoma, suffered from recurrent abdominal pain and distension, and diarrhea for six months, with inappetence. At admission, he was also diagnosed with depression. Upon physical examination, the patient presented with a 1.5 cm × 2.0 cm alopecia areata on his right occiput. Due to the negative results of laboratory testing, capsule endoscopy, and colonoscopy, the patient was diagnosed with noninfectious diarrhea, depressive disorder, and patchy alopecia areata. Considering that noninfectious diarrhea in the elderly patient was mainly caused by gut dysbiosis, he was given six rounds of FMT. His diarrhea improved remarkably one month after FMT, with improved appetite and disappearance of abdominal pain, distension, and depressive symptoms. Surprisingly, he reported new hair growth on the affected region of his scalp, with some of his white hair gradually turning to black, without taking any other therapies for alopecia areata before and after FMT.

CONCLUSION

FMT might act as a potential therapy for patients who suffer from alopecia areata. Large and well-designed studies are required to confirm the role of FMT in alopecia areata.

Alopecia areata: a review of disease pathogenesis

BACKGROUND

Alopecia areata is a disorder that results in nonscarring hair loss. The psychological impact can be significant, leading to feelings of depression and social isolation. Objectives In this article, we seek to review the pathophysiological mechanisms proposed in recent years in a narrative fashion.

METHODS

We searched MEDLINE and Scopus for articles related to alopecia areata, with a particular emphasis on its pathogenesis.

RESULTS

The main theory of alopecia areata pathogenesis is that it is an autoimmune phenomenon resulting from a disruption in hair follicle immune privilege. What causes this breakdown is an issue of debate. Some believe that a stressed hair follicle environment triggers antigen presentation, while others blame a dysregulation in the central immune system entangling the follicles. Evidence for the latter theory is provided by animal studies, as well investigations around the AIRE gene. Different immune-cell lines including plasmacytoid dendritic cells, natural killer cells and T cells, along with key molecules such as interferon-γ, interleukin-15, MICA and NKG2D, have been identified as contributing to the autoimmune process.

CONCLUSIONS

Alopecia areata remains incurable, although it has been studied for years. Available treatment options at best are beneficial for milder cases, and the rate of relapse is high. Understanding the exact mechanisms of hair loss in alopecia areata is therefore of utmost importance to help identify potential therapeutic targets.

Alopecia areata and the gut-the link opens up for novel therapeutic interventions

INTRODUCTION

This review aims to raise the potential of the modern society's impact on gut integrity often leading to increased intestinal permeability, as a cause or driver of Alopecia Areata (AA) in genetically susceptible people. With the increasing rate of T cell-driven autoimmunity, we hypothesize that there is a common root cause of these diseases that originates from chronic inflammation, and that the gut is the most commonly exposed area with our modern lifestyle. Areas covered: We will discuss the complexity in the induction of AA and its potential link to increased intestinal permeability. Our main focus will be on the gut microbiome and mechanisms involved in the interplay with the immune system that may lead to local and/or peripheral inflammation and finally, tissue destruction. Expert opinion: We have seen a link between AA and a dysfunctional gastrointestinal system which raised the hypothesis that an underlying intestinal inflammation drives the priming and dysregulation of immune cells that lead to hair follicle destruction. While it is still important to resolve local inflammation and restore the IP around the hair follicles, we believe that the root cause needs to be eradicated by long-term interventions to extinguish the fire driving the disease.