Updates in the Pathogenesis of Alopecia Areata

April 2021 in “ Sohag Medical Journal ”

Zeinab Abu Baha Gouda, Essam Nada, Hanan Assaf, Soha Aboeldahab

alopecia areata immune privilege hair follicles autoreactive effector T cells NKG2D+ CD8+ cytotoxic T cells NK cells JAK/STAT pathway MICA IFN‐γ IL-15 T cells cytotoxic T cells natural killer cells interferon gamma interleukin-15

From the encyclopedia

Alopecia Areata →

autoimmune disorder causing patchy hair loss

Mica →

Studysummary This review outlines the proposed theories behind the development of alopecia areata, emphasizing the autoimmune process involving lost immune privilege in hair follicles, and stresses the need to pinpoint specific pathogenic mechanisms for potential treatments.

Our plain-language summary. Not medical advice or a treatment recommendation. Consult a qualified healthcare professional before changing treatment. Full disclaimer

The document from April 2021 discusses alopecia areata, an autoimmune disorder that leads to non-scarring hair loss and can significantly affect patients' mental health. The pathogenesis of alopecia areata is believed to involve the collapse of the immune privilege of hair follicles, which may be triggered by a disturbance within the follicle environment or by a dysregulated central immune system. Genetic factors are implicated, with several gene loci identified in association with the condition. Key immune players in the disease process include autoreactive effector T cells, NKG2D+ CD8+ cytotoxic T cells, NK cells, the JAK/STAT pathway, MICA, IFN‐γ, and IL-15. Currently, there is no accepted cure for alopecia areata, and treatment responses are unpredictable. Understanding the precise pathogenic mechanisms is crucial for developing targeted therapies.

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research Possible Role of ILC1 in the Pathogenesis of Alopecia Areata

3 citations , April 2019 in “The journal of investigative dermatology/Journal of investigative dermatology”

This research suggests that innate lymphoid cells type 1 (ILC1) may contribute to the development of alopecia areata, alongside CD8+ T cells, by disrupting hair follicle immune privilege and promoting features of the disease.

research Vitamin D and Alopecia Areata: Possible Roles in Pathogenesis and Potential Implications for Therapy

14 citations , January 2019 in “PubMed”

This review examines the potential roles of vitamin D in the pathogenesis of alopecia areata and suggests that vitamin D analogs like calcipotriol may have therapeutic potential.

research Alopecia Areata: Overview and Insights from January 2018

290 citations , December 2017 in “Journal of The American Academy of Dermatology”

This article reviews the epidemiology, clinical evaluation, and pathogenesis of alopecia areata and highlights recent advancements, but it does not report new clinical findings.

research Identification of Differentially Expressed miRNAs in Alopecia Areata That Target Immune-Regulatory Pathways

14 citations , March 2017 in “Genes and immunity”

Certain microRNAs may help treat alopecia areata by targeting immune pathways.

research Changes of Serum Trace Elements Level in Patients with Alopecia Areata: A Meta-Analysis

23 citations , February 2017 in “Journal of dermatology”

This meta-analysis suggests that patients with alopecia areata have lower serum levels of zinc and selenium compared to healthy controls, which may be important risk factors for the condition.

The Contributory Roles of Th17 Lymphocyte and Cytotoxic T Lymphocyte at the Hair Bulge Region and Hair Bulb Area in Chronic Alopecia Areata Patients

research The Contributory Roles of Th17 Lymphocyte and Cytotoxic T Lymphocyte at the Hair Bulge Region and Hair Bulb Area in Chronic Alopecia Areata Patients

18 citations , January 2017 in “Annals of dermatology/Annals of Dermatology”

This study found that Th17 lymphocytes may play a more crucial role than cytotoxic T cells in the development of alopecia areata due to their infiltration around the hair bulb/bulge, which exacerbates hair loss as histopathological grade worsens.

research Oxidative Damage Control in a Human Mini-Organ: Nrf2 Activation Protects Against Oxidative Stress-Induced Hair Growth Inhibition

58 citations , October 2016 in “Journal of Investigative Dermatology”

This study found that activating Nrf2 in human hair follicles significantly reduced oxidative stress, lipid peroxidation, and protected against hair growth inhibition, suggesting a protective role for Nrf2 against redox insult in this context.

research CXCR3 Blockade Inhibits T Cell Migration Into the Skin and Prevents Development of Alopecia Areata

64 citations , July 2016 in “Journal of Immunology”

In this study, blocking the CXCR3 receptor in mice prevented the development of alopecia areata by inhibiting the accumulation of specific T cells in the skin, suggesting a potential therapeutic approach for humans.

research Laser Capture Microdissection Reveals Transcriptional Abnormalities In Alopecia Areata Before, During, And After Active Hair Loss

16 citations , December 2015 in “Journal of Investigative Dermatology”

This study found significant gene expression abnormalities in hair follicles affected by alopecia areata, suggesting persistent changes that may predispose to future relapses even after hair regrowth.

research Pharmacologic Inhibition of JAK-STAT Signaling Promotes Hair Growth

159 citations , October 2015 in “Science Advances”

This study observed that applying JAK-STAT pathway inhibitors to mouse and human skin led to rapid hair growth by inducing the anagen phase of hair follicles.

research Imbalance of T-Helper 17 and Regulatory T Cells in Patients with Alopecia Areata

62 citations , June 2015 in “The Journal of Dermatology”

This study found that patients with alopecia areata had higher levels of Th17 cells and lower levels of regulatory T cells compared to healthy controls, suggesting an immune imbalance in these patients.

research Translational Positioning of Janus Kinase (JAK) Inhibitors in Alopecia Areata

11 citations , April 2015 in “EBioMedicine”

This research highlights that JAK inhibitors, such as baricitinib, may effectively reverse symptoms of alopecia areata by targeting specific immune pathways, though safety and efficacy require further investigation.

research Association Between TLR1 Polymorphisms and Alopecia Areata

20 citations , April 2014 in “Autoimmunity”

In this study, TLR1 gene polymorphism rs4833095 was significantly associated with increased susceptibility to alopecia areata in the Korean population.

research Hair Follicle Mesenchyme-Associated PD-L1 Regulates T-Cell Activation Induced Apoptosis: A Potential Mechanism of Immune Privilege

53 citations , September 2013 in “Journal of Investigative Dermatology”

This study suggests that cultured hair follicle dermal sheath cup cells exhibit immune privilege properties, partly through the expression of PD-L1, which impacts co-cultured immune cells' behavior.

research Oxidative Stress in Alopecia Areata: A Case-Control Study

62 citations , July 2013 in “American Journal of Clinical Dermatology”

This study found that alopecia areata patients had higher oxidative stress and lipid peroxidation levels than healthy controls, suggesting potential involvement in the disease's pathogenesis.

research Somatostatin Expression in Human Hair Follicles and Its Potential Role in Immune Privilege

27 citations , January 2013 in “The journal of investigative dermatology/Journal of investigative dermatology”

This study identified somatostatin as a potential secretory factor contributing to the immune privilege of human hair follicles.

research Autoimmune Disease Induction in a Healthy Human Organ: A Humanized Mouse Model of Alopecia Areata

75 citations , October 2012 in “Journal of Investigative Dermatology”

This study developed an animal model that recreates alopecia areata by injecting healthy human skin grafts in immunocompromised mice with peripheral blood mononuclear cells enriched for NKG2D+ and CD56+ cells.

research Abnormal Epigenetic Modifications in Peripheral Blood Mononuclear Cells from Patients with Alopecia Areata

48 citations , September 2011 in “British Journal of Dermatology”

This study found that DNA methylation and histone modification status were altered in peripheral blood mononuclear cells of patients with alopecia areata, suggesting these changes may contribute to the disease's pathological immune responses.

Transcriptional Profiling in Alopecia Areata Defines Immune and Cell Cycle Control Related Genes Within Disease-Specific Signatures

research Transcriptional Profiling in Alopecia Areata Defines Immune and Cell Cycle Control Related Genes Within Disease-Specific Signatures

61 citations , September 2010 in “Genomics”

This study found distinct gene expression profiles in alopecia areata-affected skin, suggesting T-cell mediated immune responses and unique gene profiles between different stages of the disease.

research Trichohyalin Is a Potential Major Autoantigen in Human Alopecia Areata

66 citations , July 2010 in “Journal of Proteome Research”

This study suggests that an immune response to trichohyalin and keratin 16 may contribute to the pathogenesis of alopecia areata.

research Genome-Wide Association Study in Alopecia Areata Implicates Both Innate and Adaptive Immunity

717 citations , June 2010 in “Nature”

This study identified key genetic regions associated with alopecia areata, highlighting both acquired and innate immune involvement, with a novel link to the upregulation of ULBP ligands in autoimmune disease.

research Type 1 Interferon Signature in the Scalp Lesions of Alopecia Areata

52 citations , March 2010 in “British Journal of Dermatology”

This study demonstrated the expression of type 1 interferon-related proteins in inflammatory lesions of alopecia areata, showing a distinct distribution pattern compared to cicatricial alopecia.

research Alopecia Areata Update

391 citations , January 2010 in “Journal of The American Academy of Dermatology”

This article reviews the clinical presentation and histopathologic features of alopecia areata and proposes a hypothesis for its development, but it reports no new clinical results.

research Probing the Effects of Stress Mediators on the Human Hair Follicle

159 citations , November 2007 in “American Journal of Pathology”

In this study, researchers found that substance P triggered premature catagen development and immune changes in human scalp hair follicles, providing a possible biological link between stress and hair loss conditions like telogen effluvium and alopecia areata.