Immunological Properties of Atopic Dermatitis-Associated Alopecia Areata

Exploring the Complexities of Atopic Dermatitis: Pathophysiological Mechanisms and Therapeutic Approaches

Atopic dermatitis (AD) is a prevalent inflammatory skin condition impacting both children and adults globally, with a prevalence of 15-30%. It ranks as the most prevalent skin disorder based on disability-adjusted life-years by the World Health Organization. It presents with symptoms like skin irritation, redness, dryness, itchiness, and vesicular blisters and commonly coexists with other atopic symptoms like allergic rhinitis, asthma, and food allergies. The pathophysiology involves a complex interplay of genetic predispositions, immunological dysfunctions, and environmental factors leading to tissue inflammation and disrupted skin barrier integrity. Alopecia areata is characterized by nonscarring hair loss and shares correlations with AD including a higher prevalence of atopic diseases, shared intracellular mechanisms involving the JAK-STAT pathway, and potential treatment overlap such as dupilumab. These correlations could direct new areas of research and increased insight for both diseases. Treatment of AD requires a personalized approach due to its complex, multifactorial nature integrating nonpharmacological interventions like skin hydration and trigger avoidance as well as topical and systemic approaches, if necessary, with topical corticosteroids being the first line for flares; long term corticosteroid use poses risk for adverse effects like skin atrophy. Severe cases may require systemic treatments or phototherapy. Future treatment prospects include targeting the dysbiotic microbiome and identifying biomarkers for tailored therapeutic strategies, emphasizing the importance of personalized medicine in optimizing AD management.

Type-2 immunity associated with type-1 related skin inflammatory diseases: friend or foe?

Chronic inflammatory skin diseases are multifactorial diseases that combine genetic predisposition, environmental triggers, and metabolic disturbances associated with abnormal immune responses. From an immunological perspective, the better understanding of their physiopathology has demonstrated a large complex network of immune cell subsets and related cytokines that interact with both epidermal and dermal cells. For example, in type-1-associated diseases such as alopecia areata, vitiligo, and localized scleroderma, recent evidence suggests the presence of a type-2 inflammation that is well known in atopic dermatitis. Whether this type-2 immune response has a protective or detrimental impact on the development and chronicity of these diseases remains to be fully elucidated, highlighting the need to better understand its involvement for the management of patients. This mini-review explores recent insights regarding the potential role of type-2-related immunity in alopecia areata, vitiligo, and localized scleroderma.

Abrocitinib Improved Dupilumab-Resistant Severe Atopic Dermatitis with Comorbid Mild Alopecia Areata in a 12-Year-Old Boy: A Case Report with 1-Year Follow-Up

Atopic dermatitis (AD) may sometimes be comorbid with alopecia areata (AA). However, traditional treatments for AA show limited efficacy. New treatment options, such as dupilumab and Janus kinase inhibitors, have proven efficacy in addressing both AD and AA. This article highlights the challenging case of a 12-year-old boy experiencing severe refractory AD and comorbid AA treated with oral abrocitinib after dupilumab failure with 1-year follow-up. After 3 months of treatment, his skin manifestations improved and the hair completely regenerated. No adverse reactions were observed during the 1-year follow-up period. This case provides evidence of the efficacy and safety of using abrocitinib to treat pediatric patients with both AD and AA.

Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases

Hair-loss diseases comprise heterogenous conditions with respective pathophysiology and clinicopathological characteristics. Major breakthroughs in hair follicle biology and immunology have led to the elucidation of etiopathogenesis of non-scarring alopecia (e.g., alopecia areata, AA) and cicatricial alopecia (e.g., lichen planopilaris, LPP). High-throughput genetic analyses revealed molecular mechanism underlying the disease susceptibility of hair loss conditions, such as androgenetic alopecia (AGA) and female pattern hair loss (FPHL). Hair loss attracted public interest during the COVID-19 pandemic. The knowledge of hair loss diseases is robustly expanding and thus requires timely updates. In this review, the diagnostic and measurement methodologies applied to hair loss diseases are updated. Of note, novel criteria and classification/scoring systems published in the last decade are reviewed, highlighting their advantages over conventional ones. Emerging diagnostic techniques are itemized with clinical pearls enabling efficient utilization. Recent advances in understanding the etiopathogenesis and management for representative hair diseases, namely AGA, FPHL, AA, and major primary cicatricial alopecia, including LPP, are comprehensively summarized, focusing on causative factors, genetic predisposition, new disease entity, and novel therapeutic options. Lastly, the association between COVID-19 and hair loss is discussed to delineate telogen effluvium as the predominating pathomechanism accounting for this sequela.

Allergen desensitization reduces the severity of relapsed alopecia areata in dust-mite allergic patients

Atopy may be a facilitating factor in some alopecia areata (AA) patients with early disease onset and more severe/extensive AA. The underlying immune mechanisms are unknown, but allergen responses may support a pro-inflammatory environment that indirectly promotes AA. To investigate the long-term effect of allergen immunotherapy (AIT) against house dust mite (HDM) allergy on disease severity and prognosis for AA patients. An observational comparative effectiveness study was conducted on 69 AA patients with HDM allergy. 34 patients received conventional/traditional AA treatment (TrAA) plus AIT (AIT-TrAA), and 35 patients received TrAA alone. Serum total immunoglobulin E (tIgE), HDM specific IgE (sIgE), HDM specific IgG4 (sIgG4) and cytokines (IL-4, IL-5, IL-10, IL-12, IL-13, IL-33, IFNγ) were quantified in these patients, together with 58 non-allergic AA patients and 40 healthy controls. At the end of the 3-year desensitization course, the AIT-TrAA group presented with lower SALT scores than the TrAA group, especially in non-alopecia totalis/universalis (AT/U) patients and pre-adolescent AT/U patients (age ≤ 14). In patients with elevated tIgE levels before AIT, a decrease in tIgE was correlated to reduced extent of AA on completion of the AIT course. After desensitization, elevation of IL-5 and decrease of IL-33 were observed in HDM allergic-AA patients. Desensitization to HDM in allergic AA patients reduces the severity of relapse-related hair loss over the 3-year AIT treatment course, possibly via opposing Th2 dominance. This adjunctive treatment may help reduce disease severity and curtail the disease process in allergic patients with AA.

Dupilumab-associated cutaneous adverse events among adult patients with atopic dermatitis: A retrospective study

Dupilumab, a monoclonal antibody inhibiting interleukin (IL) 4 and IL-13, is approved for the treatment of moderate to severe atopic dermatitis (AD) in children aged ≥6 years, adolescents, and adults. Both clinical trials and real-life data demonstrate its efficacy and safety. However, some cutaneous adverse events (cAEs) have been observed during real-world experiences. The authors' aim was to analyze the spectrum of cAEs in patients receiving dupilumab for the treatment of AD in a real-world setting. A retrospective review of electronic medical records was conducted for 916 patients (475 males and 541 females; mean age, 50.23 ± 19.66 years [range, 18-91 years]) who had received dupilumab for a minimum of 1 month for the treatment of AD from December 2018 to November 2022 at the Department of Dermatology of University Federico II of Naples (Italy). The mean duration of dupilumab treatment was 27.31 ± 21.26 months. A total of 148 of 916 (16.15%) (90 males; mean age, 50.91 ± 15.34 years) patients reported other cAEs apart of AD flare; namely, facial redness (82 of 916; 8.95%), psoriasis (39 of 916; 4.25%), alopecia areata (11 of 916; 1.2%), skin peeling (11 of 916; 1.2%), parapsoriasis (three of 916; 0.32%), and vitiligo (two of 916; 0.21%). Thirty-one of 916 (3.38%) patients discontinued dupilumab because of cAEs (18 of 916; 1.96%) for facial redness, 10 of 916 (1.09%) for psoriasis, and three of 916 (0.32%) for parapsoriasis. In our population, most of the cAEs were mild and did not require discontinuation of dupilumab. These findings would enable dermatologists understand the cutaneous side effects of dupilumab better, resulting in improved treatment plan decisions in clinical practice.

Recent insights into comorbidities in atopic dermatitis

INTRODUCTION

The relationship between atopic dermatitis and atopic diseases such as food allergies, asthma, and allergic rhinitis in terms of co-occurrence, underlying mechanisms, and therapy is well documented. There is increasing evidence that atopic dermatitis is associated with non-atopic comorbidities such as cardiac, autoimmune, and neuropsychological comorbidities, as well as cutaneous and extracutaneous infections, establishing atopic dermatitis as a systemic disease.

AREAS COVERED

The authors reviewed evidence on atopic and non-atopic comorbidities of atopic dermatitis. A literature search was conducted in PubMed for peer-reviewed articles published until October 2022.

EXPERT OPINION

Atopic and non-atopic diseases coexist with atopic dermatitis more often than would be expected by chance. The effect of biologics and small molecules on atopic and non-atopic comorbidities may contribute to a better understanding of the relationship between atopic dermatitis and its comorbidities. Their relationship needs to be explored further to dismantle the underlying mechanism and move toward an atopic dermatitis endotype-based therapeutic approach.

IL-13, periostin and dipeptidyl-peptidase-4 reveal endotype-phenotype associations in atopic dermatitis

BACKGROUND

The heterogeneous (endo)phenotypes of atopic dermatitis (AD) require precision medicine. Currently, systemic therapy is recommended to patients with an Eczema Area and Severity Index (EASI)≥16. Previous studies have demonstrated an improved treatment response to the anti-interleukin (IL)-13 antibody tralokinumab in AD subgroups with elevated levels of the IL-13-related biomarkers dipeptidyl-peptidase (DPP)-4 and periostin.

METHODS

Herein, 373 AD patients aged≥12 years were stratified by IL-13high , periostinhigh and DPP-4high endotypes using cross-sectional data from the ProRaD cohort Bonn. "High" was defined as >80th quantile of 47 non-atopic controls. We analyzed endotype-phenotype associations using machine-learning gradient boosting compared to logistic regression.

RESULTS

AD severity and eosinophils correlated with IL-13 and periostin levels. Correlations of IL-13 with EASI were stronger in patients with increased (rs=0.482) than with normal (rs=0.342) periostin levels. We identified eosinophilia>6% and an EASI range of 5.5-17 dependent on the biomarker combination to be associated with increasing probabilities of biomarkerhigh endotypes. Also patients with mild-to-low-moderate severity (EASI<16) featured increased biomarkers (IL-13high : 41%, periostinhigh : 48.4%, DPP-4high : 22.3%). Herthoge sign (adjusted Odds Ratio (aOR)=1.89, 95% Confidence Interval (CI) [1.14-3.14]) and maternal allergic rhinitis (aOR=2.79-4.47) increased the probability of an IL-13high -endotype, "dirty neck" (aOR=2.83 [1.32-6.07]), orbital darkening (aOR=2.43 [1.08-5.50]), keratosis pilaris (aOR=2.21 [1.1-4.42]) and perleche (aOR=3.44 [1.72-6.86]) of a DPP-4high -endotype.

CONCLUSIONS

A substantial proportion of patients with EASI<16 featured high biomarker levels suggesting systemic impact of skin inflammation already below the current cut-off for systemic therapy. Our findings facilitate the identification of patients with distinct endotypes potentially linked to response to IL-13-targeted therapy.

Alopecia Universalis in an Adolescent Successfully Treated with Upadacitinib-A Case Report and Review of the Literature on the Use of JAK Inhibitors in Pediatric Alopecia Areata

Alopecia areata (AA) is a cell-mediated autoimmune disease in which a cytotoxic T-cell response against hair follicles occurs. AA has been demonstrated to frequently co-exist with atopic dermatitis (AD), and the coincidence of atopy predisposes to a more severe course of the disease. To date, therapeutic options in AA, especially in the pediatric population, are mainly limited to corticosteroids, irritants, sensitizers, and immunosuppressive agents. Recently, innovative therapies have emerged, among which Janus kinase (JAK) inhibitors, effective in both AD and AA, appear to be the most promising. Here, a 14-year-old girl with alopecia universalis (AU) and mild AD is demonstrated, who was successfully treated with a selective JAK1 inhibitor, upadacitinib, which has been approved for the treatment of AD in adults and children aged 12 years and older. Resolution of eczema and complete hair regrowth was achieved after 3 months of therapy. Apart from transient mild leukopenia at weeks 4 and 8, no adverse events were noted. Data in the literature on the efficacy and safety of JAK inhibitors in the treatment of AA in the pediatric population is based on single case reports and case series. So far, topical tofacitinib and ruxolitinib, as well as systemic tofacitinib, ruxolitinib, and baricitinib have been used off-label in this indication in children. Upadacitinib is another effective treatment option with a good benefit-risk ratio for patients with AA, including cases coexisting with AD.

Is Atopic Dermatitis Only a Skin Disease?

Atopic dermatitis (AD) is a chronic, pruritic, inflammatory dermatosis that imposes significant patient and population burdens. In addition to the cutaneous signs and symptoms, growing evidence suggests that AD is systemic in nature. Certain diseases can possibly co-occur with AD as a result of coincidental exposure to similar environmental factors. However, it is also suspected that they are linked to the pathogenesis of AD through more complex genetic and immunological mechanisms, but these correlations remain less understood. It is of great need to seek explanations for the higher frequency of the number of cardiovascular, autoimmune, neurological, psychiatric, and metabolic disorders that have been observed in epidemiologic investigations among AD patients. Moreover, analysing the immunology of chronic inflammation and its correction, activation, or suppression may prevent the development of a variety of comorbidities. As comorbid diseases in patients diagnosed with AD may potentially go undetected, physicians should be aware of them.

Efficacy and safety of different JAK inhibitors in the treatment of alopecia areata: a network meta-analysis

Background

Alopecia areata (AA) is an immune disease characterized by non-scarring hair loss. With the widespread application of JAK inhibitors in immune-related diseases, attention is being given to their role in the treatment of AA. However, it is unclear which JAK inhibitors have a satisfactory or positive effect on AA. This network meta-analysis aimed to compare the efficacy and safety of different JAK inhibitors in the treatment of AA.

Methods

The network meta-analysis was performed according to the PRISMA guidelines. We included randomized controlled trials as well as a small number of cohort studies. The differences in efficacy and safety between the treatment and control groups were compared.

Results

Five randomized controlled trials, two retrospective studies, and two prospective studies involving 1689 patients were included in this network meta-analysis. In terms of efficacy, oral baricitinib and ruxolitinib significantly improved the response rate of patients compared to placebo [MD = 8.44, 95% CI (3.63, 19.63)] and [MD = 6.94, 95% CI, (1.72, 28.05)],respectively. Oral baricitinib treatment significantly improved the response rate compared to non-oral JAK inhibitor treatment [MD=7.56, 95% CI (1.32,43.36)]. Oral baricitinib, tofacitinib, and ruxolitinib treatments significantly improved the complete response rate compared to placebo [MD = 12.21, 95% CI (3.41, 43.79)], [MD = 10.16, 95% CI (1.02, 101.54)], and [MD = 9.79, 95% CI, (1.29, 74.27)], respectively. In terms of safety, oral baricitinib, tofacitinib, and ruxolitinib treatments significantly reduced treatment-emergent adverse event rates compared with conventional steroid treatment [MD = 0.08, 95% CI (0.02, 0.42)], [MD = 0.14, 95% CI (0.04, 0.55)], and [MD = 0.35, 95% CI, (0.14, 0.88)], respectively.

Conclusion

Oral baricitinib and ruxolitinib are excellent options for the treatment of AA owing to their good efficacy and safety profiles. In contrast, non-oral JAK inhibitors do not appear to have satisfactory efficacy in treating AA. However, further studies are required to verify the optimal dose of JAK inhibitors for AA therapy.

Stratification of alopecia areata reveals involvement of CD4 T cell populations and altered faecal microbiota

Alopecia areata (AA) is an immune-mediated disease that causes non-scarring hair loss. Autoreactive CD8 T cells are key pathogenic effectors in the skin, and AA has been associated both with atopy and with perturbations in intestinal homeostasis. This study aimed to investigate mechanisms driving AA by characterizing the circulating immunophenotype and faecal microbiome, and by stratifying AA to understand how identified signatures associated with heterogeneous clinical features of the condition. Flow cytometric analyses identified alterations in circulating B cells and CD4 T cells, while 16S sequencing identified changes in alpha and beta diversity in the faecal microbiome in AA. The proportions of transitional and naïve B cells were found to be elevated in AA, particularly in AA samples from individuals with >50% hair loss and those with comorbid atopy, which is commonly associated with extensive hair loss. Although significant changes in circulating CD8 T cells were not observed, we found significant changes in CD4+ populations. In individuals with <50% hair loss higher frequencies of CCR6+CD4 ("Th17") and CCR6+CXCR3+CD4 ("Th1/17") T cells were found. While microbial species richness was not altered, AA was associated with reduced evenness and Shannon diversity of the intestinal microbiota, again particularly in those with <50% hair loss. We have identified novel immunological and microbial signatures in individuals with alopecia areata. Surprisingly, these are associated with lower levels of hair loss, and may therefore provide a rationale for improved targeting of molecular therapeutics.

Dupilumab-Associated Adverse Events During Treatment of Allergic Diseases

Among the new biological therapies for atopic diseases, dupilumab is a fully human monoclonal antibody directed against IL-4Rα, the common chain of interleukin-4 and interleukin-13 receptors. Dupilumab showed clinical improvements in patients with atopic dermatitis, asthma, and chronic rhinosinusitis and is currently under development for other indications. While dupilumab is considered to be well tolerated, a number of recent publications have reported various adverse events. This review aims to summarize the current knowledge about these adverse events, which may help clinicians to improve the follow-up of patients on dupilumab. Injection-site reactions are the most common reported adverse event. However, dupilumab has also been shown to cause ophthalmic complications (e.g., dry eyes, conjunctivitis, blepharitis, keratitis, and ocular pruritus), head and neck dermatitis, onset of psoriatic lesions, progression of cutaneous T-cell lymphoma exacerbation, alopecia areata, hypereosinophilia, and arthritis. Most are managed during dupilumab treatment continuation, but some (e.g., severe conjunctivitis) may result in a discontinuation of treatment. Their molecular origin is unclear and requires further investigations. Among other hypothesis, it has been suggested that T helper (Th)2-mediated pathway inhibition may worsen Th1/Th17-dependent immune responses. An ophthalmological examination for the presence of potential predictive indicators of ophthalmic adverse events is recommended before initiation of dupilumab therapy.

Phase 2a randomized clinical trial of dupilumab (anti-IL-4Rα) for alopecia areata patients

BACKGROUND

Treatments for alopecia areata (AA) patients with extensive scalp hair loss are limited, and recent evidence supports a role for type 2 T-cell (Th2)-immune response in AA. Dupilumab, a monoclonal antibody inhibiting Th2 signaling, approved for type 2 diseases including atopic dermatitis, was evaluated in AA patients.

METHODS

Alopecia areata patients with and without concomitant atopic dermatitis were randomized 2:1 to receive weekly subcutaneous dupilumab (300 mg) or placebo for 24 weeks, followed by another 24-week dupilumab open-label phase. The primary outcome was change from baseline in the Severity of Alopecia Tool (SALT) score at week 24; secondary outcomes included a range of measures of hair regrowth.

RESULTS

Forty and 20 patients were assigned to the dupilumab and placebo arms, respectively. At week 24, disease worsening was documented in the placebo arm, with a least-squares mean change in the SALT score of -6.5 (95% confidence-interval [CI], -10.4 to -2.6), versus a change of 2.2 (95% CI, -0.6 to 4.94) in the dupilumab arm (p < .05). After 48 weeks of dupilumab treatment, 32.5%, 22.5% and 15% of patients achieved SALT₃₀ /SALT₅₀ /SALT₇₅ improvement, respectively, while in patients with baseline IgE ≥ 200 IU/ml response rates increased to 53.8%, 46.2%, and 38.5%, respectively. Moreover, baseline IgE predicts treatment response with 83% accuracy. No new safety signals were detected.

CONCLUSIONS

This hypothesis-driven trial is the first to indicate the possible pathogenic role of the Th2 axis and Th2 targeting in AA patients. Patient selection based on baseline serum IgE levels may improve treatment results (Clinicaltrials.gov number, NCT03359356).

The Role of Serum Th1, Th2, and Th17 Cytokines in Patients with Alopecia Areata: Clinical Implications

Alopecia areata is a type of non-scarring hair loss. The dysregulation of numerous systemic Th1 (IL-2, IFN-γ, TNF, IL-12, and IL-18), Th2 (IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, IL-17E, IL-31 and IL-33) and Th17 (IL-17, IL-17F, IL-21, IL-22, IL-23 and TGF-β) cytokines was observed in patients with alopecia areata. Positive correlations between the severity of alopecia areata and an increased serum level of various cytokines including IL-2, TNF, IL-12, IL-17, and IL-17E were reported in the literature. An increased serum level of numerous cytokines, such as IL-2, IL-6, TNF, IL-12, IL-17E, and IL-22, was described as positively correlated with the duration of the disease. Moreover, it was shown that increased pre-treatment serum level of IL-12 was a positive, while increased serum levels of IL-4 and IL-13 were negative prognostic markers for the efficacy of diphenylcyclopropenone. In conclusion, alopecia areata is associated with the dysregulation of systemic Th1, Th2 and Th17 cytokines with their role in the pathogenesis, clinical manifestations and prognosis of the disease. Available data indicate the most significant role of serum IL-2, TNF, IL-12, IL-17, and IL-17E as markers of disease activity. The serum levels IL-4, IL-12 and IL-13 may be useful as potential predictors of diphenylcyclopropenone efficacy.

Machine Learning-Based Deep Phenotyping of Atopic Dermatitis: Severity-Associated Factors in Adolescent and Adult Patients

Importance

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease and is driven by a complex pathophysiology underlying highly heterogeneous phenotypes. Current advances in precision medicine emphasize the need for stratification.

Objective

To perform deep phenotyping and identification of severity-associated factors in adolescent and adult patients with AD.

Design, Setting, and Participants

Cross-sectional data from the baseline visit of a prospective longitudinal study investigating the phenotype among inpatients and outpatients with AD from the Department of Dermatology and Allergy of the University Hospital Bonn enrolled between November 2016 and February 2020.

Main Outcomes and Measures

Patients were stratified by severity groups using the Eczema Area and Severity Index (EASI). The associations of 130 factors with AD severity were analyzed applying a machine learning-gradient boosting approach with cross-validation-based tuning as well as multinomial logistic regression.

Results

A total of 367 patients (157 male [42.8%]; mean [SD] age, 39 [17] years; 94% adults) were analyzed. Among the participants, 177 (48.2%) had mild disease (EASI ≤7), 120 (32.7%) had moderate disease (EASI >7 and ≤ 21), and 70 (19.1%) had severe disease (EASI >21). Atopic stigmata (cheilitis: odds ratio [OR], 8.10; 95% CI, 3.35-10.59; white dermographism: OR, 4.42; 95% CI, 1.68-11.64; Hertoghe sign: OR, 2.75; 95% CI, 1.27-5.93; nipple eczema: OR, 4.97; 95% CI, 1.56-15.78) was associated with increased probability of severe AD, while female sex was associated with reduced probability (OR, 0.30; 95% CI, 0.13-0.66). The probability of severe AD was associated with total serum immunoglobulin E levels greater than 1708 IU/mL and eosinophil values greater than 6.8%. Patients aged 12 to 21 years or older than 52 years had an elevated probability of severe AD; patients aged 22 to 51 years had an elevated probability of mild AD. Age at AD onset older than 12 years was associated with increased probability of severe AD up to a peak at 30 years; age at onset older than 33 years was associated with moderate to severe AD; and childhood onset was associated with mild AD (peak, 7 years). Lifestyle factors associated with severe AD were physical activity less than once per week and (former) smoking. Alopecia areata was associated with moderate (OR, 5.23; 95% CI, 1.53-17.88) and severe (OR, 4.67; 95% CI, 1.01-21.56) AD. Predictive performance of machine learning-gradient boosting vs multinomial logistic regression differed only slightly (mean multiclass area under the curve value: 0.71 [95% CI, 0.69-0.72] vs 0.68 [0.66-0.70], respectively).

Conclusions and Relevance

The associations found in this cross-sectional study among patients with AD might contribute to a deeper disease understanding, closer monitoring of predisposed patients, and personalized prevention and therapy.

Alopecia areata: Current understanding of the pathophysiology and update on therapeutic approaches, featuring the Japanese Dermatological Association guidelines

Alopecia areata (AA) is a relatively common nonscarring hairloss disease characterized by an autoimmune response to anagen hair follicles (HFs). Accumulated evidence suggests that collapse of the HF immune privilege subsequent to triggering events, represented by viral infection, leads to autoimmune response in which autoreactive cytotoxic CD8+NKG2D+ T cells mainly target exposed HF autoantigens. AA had been recognized as type 1 inflammatory disease, but recent investigations have suggested some roles of type 2- and Th17-associated mediators in AA pathogenesis. The significance of psychological stress in AA pathogenesis is less emphasized nowadays, but psychological comorbidities, such as depression and anxiety, attract greater interest in AA management. In this regard, the disease severity may not solely be evaluated by the extent of hair loss. Use of trichoscopy markedly improved the resolution of the diagnosis and evaluation of the phase of AA, which is indispensable for the optimization of treatment. For the standardization of AA management, the establishment of guidelines/expert consensus is pivotal. Indeed, the Japanese Dermatological Association (JDA) and other societies and expert groups have published guidelines/expert consensus reports, which mostly recommend intralesional/topical corticosteroid administration and contact immunotherapy as first-line treatments, depending on the age, disease severity, and activity of AA. The uniqueness of the JDA guidelines can be found in their descriptions of intravenous corticosteroid pulse therapy, antihistamines, and other miscellaneous domestically conducted treatments. Considering the relatively high incidence of spontaneous regression in mild AA and its intractability in severe subsets, the importance of course observation is also noted. Evidenced-based medicine for AA is currently limited, however, novel therapeutic approaches, represented by JAK inhibitors, are on their way for clinical application. In this review, the latest understanding of the etiopathogenesis and pathophysiology, and update on therapeutic approaches with future perspectives are summarized for AA, following the current version of the JDA AA management guidelines.