How Our Microbiome Influences the Pathogenesis of Alopecia Areata

This systematic review and meta-analysis found limited, low-quality evidence suggesting that platelet-rich plasma injections may increase hair density in patients with androgenetic alopecia compared to saline, but results were inconclusive for alopecia areata.

This review covers the structure, development, cycle, and molecular regulation of hair follicles but does not report new results, aiming to offer insights for addressing hair follicle-related diseases.

This study found that the scalp microbiome was more diverse in alopecia areata patients than in healthy controls, and distinctive microbial profiles may be linked to disease severity and prognosis.

In two phase 3 trials, this study found that oral baricitinib significantly improved hair regrowth compared to placebo in adults with severe alopecia areata after 36 weeks, though longer trials are needed to ascertain its long-term efficacy and safety.

In this observational study, researchers found that mini-pulse oral corticosteroids effectively reduced hair loss in alopecia areata patients who did not respond to topical therapies, though early-onset patients and those with hypothyroidism were less likely to benefit.

This review discusses the role of the skin microbiome in the pathogenesis of various skin disorders, such as atopic dermatitis and psoriasis, and reports no new clinical findings; it emphasizes potential therapeutic implications.

This review analyzed data on alopecia types associated with COVID-19, suggesting androgenetic alopecia may be a risk factor for severe COVID-19, while telogen effluvium often follows infection and alopecia areata tends to relapse in those with preexisting disease.

This review summarizes the influences of lifestyle factors such as smoking, alcohol, and diet on the pathogenesis of alopecia areata but reports no new clinical results.

In this study, Japanese patients with alopecia areata were found to have higher BMI and retinol intake, with retinol intake predicting severity of hair loss.

JAK inhibitors show promise for treating alopecia areata, but more research is needed.

This review compiles current evidence on the molecular mechanisms, etiologies, and targeted immunotherapies for alopecia areata and reports no new experimental results, emphasizing the need for further research to manage the disease.

This review discusses the role of hair follicle bacterial colonization in immune responses and the pathogenesis of alopecia but reports no new clinical results.

This study found that pentoxifylline plus topical corticosteroids had the highest treatment success rate for alopecia areata compared to no treatment, but the best overall treatment remains uncertain due to varying data.

This review discusses immune privilege in anagen hair follicles and its collapse in alopecia areata, emphasizing the importance of restoring this function for effective management and disease relapse prevention.

This study found significant differences in scalp microbiome composition and volatile organic metabolites between individuals with alopecia areata and healthy controls, suggesting potential microbiome-related therapeutic interventions for hair growth disorders.

In this randomized double-blind study, 160 adults with alopecia areata showed significant improvements in hair loss severity after using a bioactive peptide cosmetic product that mimics platelet-rich plasma, while the placebo group showed no significant change, underlining the treatment's potential effectiveness.

This Italian guideline discusses the diagnosis and treatment of alopecia areata but reports no new clinical trial results; the authors highlight the need for well-designed studies.

In this case report, an 86-year-old man experienced new hair growth and color change in alopecia areata after receiving fecal microbiota transplantation for noninfectious diarrhea.

This study found that T-regulatory cells, specifically the FOXP3 CD39 subset, were significantly reduced in both circulation and hair follicles of alopecia areata patients compared to healthy subjects, suggesting potential therapeutic targets.

This study identified 14 genes affected by copy number variants that may contribute to alopecia areata, including four genes notably involved in autophagy and chromatin remodeling.

This study observed that hair follicles in hair loss patients had increased levels of Propionibacterium acnes, potentially linked to elevated immune response gene expression in miniaturized hair follicles.

This meta-analysis found that the rs2476601 SNP of the PTPN22 gene is significantly associated with reduced susceptibility to alopecia areata, with carriers of the C-allele and CC-genotype having a lower risk.

This review discusses the mechanisms behind alopecia areata and primary cicatricial alopecia and reports no new clinical results, aiming to guide the development of targeted treatments.

This review explores the hair follicle microbiome's interaction with the immune system, discussing its potential clinical implications for scalp health and disease but reports no new clinical results.

This study observed a microbial shift on the scalp of Alopecia areata patients, characterized by an increase in Propionibacterium acnes and a decrease in Staphylococcus epidermidis, compared to healthy controls.

This review discusses genetic and environmental factors contributing to autoimmunity in alopecia areata and reports no new clinical findings, emphasizing the need for further study on its aetiology and pathophysiology.

This study found that oral pulse steroids significantly reduced serum and tissue levels of TNF-α in patients with alopecia areata, correlating with clinical improvement.

This study found that alopecia areata is linked with a higher prevalence of systemic and psychiatric diseases, suggesting that physicians should monitor for these potential comorbidities.

This review discusses how modern lifestyle factors affecting gut health may contribute to Alopecia Areata in genetically predisposed individuals, reporting no new results but suggesting the need for long-term interventions.

This study reviewed recent theories on alopecia areata's pathogenesis, highlighting its autoimmune nature due to immune privilege disruption in hair follicles, and noted current treatments have limited efficacy with high relapse rates, underscoring the need for further research into its mechanisms for better therapies.

This article reviews the role of perifollicular regulatory T cells in maintaining hair follicle integrity in the context of hidradenitis suppurativa and calls attention to inflammatory mechanisms without reporting new clinical results.

This review explores nail changes associated with alopecia areata, noting their prevalence and impact on appearance and function, but reports no new clinical findings; the authors call for larger controlled trials.

This review examines the literature on autoimmune hair loss disorders, highlighting the collapse of immune privilege and the potential role of neurogenic stress in this process, but reports no new clinical results.

This review discusses the role of immune privilege collapse in the pathogenesis of alopecia areata, emphasizing the potential for therapeutic manipulation of hair bulb immune privilege to offer new treatment options, and reports no new results.

This study suggests that targeting specific immune pathways, such as IL-12/23 and Th2 cytokines, may offer new treatment options for alopecia areata, a T-cell-mediated disease without current mechanism-specific therapies.

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

The gut microbiome affects the development of alopecia areata.

The researchers reported that hair follicle development and commensal microbe colonization promote the accumulation of regulatory T cells in neonatal skin, with the Ccl20-Ccr6 pathway playing a key role in this process.

This review discusses the complex relationship between stress and various skin conditions, highlighting the role of the skin in the stress response and the brain-skin communication pathways, but reports no new research findings.

This study provides suggestive evidence that duplications in the MCHR2 gene may be involved in the pathogenesis of alopecia areata.

This review examines the immunological aspects of alopecia areata, focusing on genetic, neuroimmunological, and immune privilege factors, but does not report new clinical findings.

This review explores animal models of alopecia areata, particularly focusing on the insights they've provided into the disease's immune mechanisms and potential treatment approaches, without reporting new experimental data.

This review reports that alopecia areata affects about 2% of people globally and is linked with psychiatric and medical comorbidities, highlighting its significant disease burden.

This review discusses the histologic features of nonscarring alopecia and highlights the importance of clinical-pathological correlation for accurate diagnosis, but reports no new clinical results.

This study found that specific SNPs in the CXCL1 and CXCL2 genes may be associated with increased susceptibility to alopecia areata in the Korean population.

This study found that JAK inhibitors promote hair regrowth in both mice and human alopecia areata cases by blocking key immune pathways involved in disease development.

This review summarizes the anatomical and physiological aspects of human hair and its clinical significance, but does not report new research findings.

This study suggests that the 5’UTR SNP rs6457452 of HSPA1B may be associated with the onset of Alopecia Areata and reduced susceptibility in the Korean population.

This study highlights rapid advances in alopecia areata treatment following the identification of genetic variants associated with increased disease risk, suggesting potential for precision medicine approaches.

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.

This case series suggests that Propionibacterium acnes colonization may contribute to the development of hair casts and diffuse non-scarring alopecia, as patients' symptoms improved with antibiotics targeting the bacteria.

Other common signs, not just the well-known immune cells around hair bulbs, are important for diagnosing hair loss from alopecia areata.

This review discusses low-level light therapy for androgenetic alopecia and female pattern hair loss, noting minimal clinical evidence on its efficacy and the need for more controlled studies.

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.

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.

This study found a decreased number of follicular melanocytes in patients with alopecia areata, though it remains unclear if this decrease is due to autoimmune attack or rapid hair cycling.

This research highlights that psychological stress can adversely affect hair growth in mice, implicating potential pathways that may be relevant in understanding stress-induced hair growth inhibition in humans.

This review of randomized controlled trials for alopecia areata treatments found that none were significantly better than placebo in promoting long-term hair growth, with most trials being small and poorly reported.

This study observed that acute diffuse and total alopecia, a subtype of alopecia areata, typically resolves rapidly and spontaneously within about six months, even without treatment, suggesting a favorable prognosis.

This review of interventions for alopecia areata found no significant treatment benefits for hair growth compared to placebo, indicating a need for larger, well-conducted studies.

This study suggests that human hair follicles may actively suppress natural killer cells, which contrasts with the observed defects in NK cell regulation in alopecia areata.

This study found that human scalp hair follicles can respond to corticotropin releasing hormone stimulation similarly to the classical HPA axis, including up-regulating cortisol production and activating neuroendocrine feedback loops.

This study found that betamethasone valerate foam was more effective and well-tolerated than betamethasone dipropionate lotion in treating mild-to-moderate alopecia areata, with higher hair regrowth rates observed.

This study found that psychoemotional stress disrupts hair growth in mice by terminating anagen and suggests a potential pathway for pharmacological management of stress-related hair loss in humans.

This study found that increasing dietary soy oil content reduced alopecia areata development in C3H/HeJ mice, though genistein injection showed no significant effect.