Recombinant human hepatitis B vaccine initiating alopecia areata: testing the hypothesis using the C3H/HeJ mouse model

Pathophysiology of Alopecia Areata in the Pediatric Patient

Alopecia areata (AA) is an autoimmune non-scarring hair loss that arises in genetically susceptible individuals, potentially in combination with environmental triggers or inciting events, of which the exact mechanism is not yet fully understood. Genome wide association studies have demonstrated an association between AA and variants in HLA haplotypes on chromosome 6 which correlate with other autoimmune conditions as well as other gene variants. Familial and twin studies also confer additional evidence to a genetic component. AA pathogenesis relies on immune privilege collapse at the hair follicle (HF) bulb in the anagen hair cycle phase. Immune privilege collapse is associated with upregulation of IFN-γ, ultimately activating JAK-STAT pathway resulting in upregulation of MHC class I and II in the HF and subjecting it to attack by NKG2D+ CD8 T cells. The complex interplay between pro-inflammatory cytokines such as IFN-γ, IL-2, IL-15 and their use of JAK-STAT signaling are important in perpetuation of AA.

Alopecia Areata: An Autoimmune Disease of Multiple Players

Alopecia areata (AA) is an autoimmune disease of the hair follicles. It is characterized by a well-defined non-scarring alopecic patch or patches that may extend to the entire scalp or lead to total body hair loss. Due to its unpredictable clinical course, AA causes substantial psychological harm. Despite the high prevalence of this disease and extensive research, its exact pathomechanism is unclear, and current treatments have a high relapse rate that has deemed AA incurable. Over the past few decades, researchers have investigated multiple potential factors that may help alleviate its pathogenesis and provide effective treatment. Given its complex immunopathogenesis, AA is considered an autoimmune disease with multiple factors. This review gathers current evidence that emphasizes molecular mechanisms, possible causative etiologies, and targeted immunotherapies for AA. Understanding its underlying mechanisms may shed light on new strategies to effectively manage AA in the future.

IFN-α and TNF-α serum levels and their association with disease severity in Egyptian children and adults with alopecia areata

BACKGROUND

Alopecia areata (AA) is an autoimmune skin disease characterized by abnormal levels of several cytokines, such as interferon alpha (IFN-α) and tumor necrosis factor-alpha (TNF-α), which are T-helper type 1 cytokines that have important roles in the pathogenesis of AA. The aim of our study was to correlate circulating IFN-α and TNF-α levels with disease severity, activity, and clinical type in patients with AA and to evaluate the relationship between the two cytokines.

METHODS

We investigated serum IFN-α and TNF-α levels in 72 patients with AA (35 children and 35 adults) and 75 healthy control individuals (34 children and 41 adults) using the enzyme-linked immunosorbent assay (ELISA) technique. We evaluated AA severity using the Severity of Alopecia Tool (SALT) and determined the activity based on dermoscopic criteria of disease activity.

RESULTS

Serum IFN-α and TNF-α concentrations were significantly higher in the patients than in the controls. There was a significant positive correlation between serum IFN-α and TNF-α levels in all patients with alopecia areata, as well as between serum TNF-α levels and disease severity in all patients and in children.

CONCLUSIONS

Our results support the association between IFN-α and TNF-α levels and AA and suggest that TNF-α might be related to disease severity.

Immunology of alopecia areata

Alopecia areata is a condition that affects hair follicles and leads to hair loss ranging from small well-defined patches to complete loss of all body hair. Despite its high incidence, the pathobiology is not fully understood, and no single concept could be universally accepted.

Alopecia areata is mostly considered to be an autoimmune disease, in which the collapse of hair follicle immune privilege plays a key role. Higher incidence rate in the female population and increased overall risk of other autoimmune disorders militate in favor of autoimmune hypothesis. Antibodies against multiple components of hair follicles almost exclusively attack in anagen phase, where melanogenesis takes place. It suggests involvement of melanogenesis-associated autoantigens as a target epitope.

Some investigators believed that alopecia areata is not a truly autoimmune disease but is only ‘consistent with’ autoimmune mechanisms. High frequency of a positive family history up to 42% may reflects the contribution of heredity factors. In addition, no specific target autoantigen has been identified so far, and autoantibodies to hair follicle-associated antigens are detectable in normal individuals.

A "hair-raising" history of alopecia areata

A 3500-year-old papyrus from ancient Egypt provides a list of treatments for many diseases including "bite hair loss," most likely alopecia areata (AA). The treatment of AA remained largely unchanged for over 1500 years. In 30 CE, Celsus described AA presenting as scalp alopecia in spots or the "windings of a snake" and suggested treatment with caustic compounds and scarification. The first "modern" description of AA came in 1813, though treatment still largely employed caustic agents. From the mid-19th century onwards, various hypotheses of AA development were put forward including infectious microbes (1843), nerve defects (1858), physical trauma and psychological stress (1881), focal inflammation (1891), diseased teeth (1902), toxins (1912) and endocrine disorders (1913). The 1950s brought new treatment developments with the first use of corticosteroid compounds (1952), and the first suggestion that AA was an autoimmune disease (1958). Research progressively shifted towards identifying hair follicle-specific autoantibodies (1995). The potential role of lymphocytes in AA was made implicit with immunohistological studies (1980s). However, studies confirming their functional role were not published until the development of rodent models (1990s). Genetic studies, particularly genome-wide association studies, have now come to the forefront and open up a new era of AA investigation (2000s). Today, AA research is actively focused on genetics, the microbiome, dietary modulators, the role of atopy, immune cell types in AA pathogenesis, primary antigenic targets, mechanisms by which immune cells influence hair growth, and of course the development of new treatments based on these discoveries.

Impact of Psychosocial Profile on Alopecia Areata in Pediatric Patients: A Case Control Study from A Tertiary Care Hospital in Eastern Uttar Pradesh

Background:

Alopecia areata (AA) is a common form of nonscarring alopecia characterized by patchy loss of hair from the scalp and body. It is a complex outcome of factors such as autoimmunity, genetic factors, infectious diseases, as well as psychological factors, such as stress, personality type, familial conditions. Around 20% of patients are in the pediatric age group, and 60% of the patients develop AA before the age of 20 years.

Aim:

The present study looked into the impact of psychosocial factors in AA.

Materials and Methods:

This was a case-control study conducted over a period of 1 year. One hundred and two patients and age and gender-matched control group between the ages of 2 and 14 years were included. A questionnaire was administered to identify the stress arising due to personal or familial conditions, school-related issues, psychotrauma or illness, and accidents prior to developing AA. Age and gender-matched patients with other dermatoses with low psychosomatic component to it and unlikely to be influenced by stress were selected as control.

Result:

Fifty-three patients (52 %) were male and 49 were female (48 %). Fifty-five (53.9%) patients were in the age group of 10 to 14 years. Forty (39.2%) children had multiple patches. Onset was <5 months in 30 patients (29.4%). Forty-nine (48%) children reported stress due to school-related issues compared to 13 (12.7%) in the control group. Eighteen (17.6%) children had familial issues compared to 6 (0.05%) in the control group. Nineteen children (18.6%) had multiple stressors. Sixty-nine (67.6%) patients related their disease to a stress component compared to 33 (32.3%) who could not relate to any stress. A significant association was noted between examination pressure and academic performance with onset of AA compared to control (P < 0.05%), which was stronger among female compared to male.

Conclusion:

The psychological profile and comorbidities have a significant impact on the onset or recidivism of AA. Impact of a stressful personal or family life, parental pressure to perform better in school, and psychological vulnerability can significantly contribute to the onset or exacerbation of AA.

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

Alopecia areata is an autoimmune disorder characterized by transient, non-scarring hair loss and preservation of the hair follicle. Hair loss can take many forms ranging from loss in well-defined patches to diffuse or total hair loss, which can affect all hair-bearing sites. Patchy alopecia areata affecting the scalp is the most common type. Alopecia areata affects nearly 2% of the general population at some point during their lifetime. Skin biopsies of affected skin show a lymphocytic infiltrate in and around the bulb or the lower part of the hair follicle in the anagen (hair growth) phase. A breakdown of immune privilege of the hair follicle is thought to be an important driver of alopecia areata. Genetic studies in patients and mouse models have shown that alopecia areata is a complex, polygenic disease. Several genetic susceptibility loci were identified to be associated with signalling pathways that are important to hair follicle cycling and development. Alopecia areata is usually diagnosed based on clinical manifestations, but dermoscopy and histopathology can be helpful. Alopecia areata is difficult to manage medically, but recent advances in understanding the molecular mechanisms have revealed new treatments and the possibility of remission in the near future.

Alopecia Areata After Vaccination: Recurrence with Rechallenge

Alopecia areata (AA) is the most common form of hair loss in children. We report the case of a child who had two episodes of AA after two different vaccines with complete hair regrowth between the episodes. This case supports the concept that vaccination might be a trigger for the development of AA in genetically predisposed children.

Vaccines, adjuvants and autoimmunity

Vaccines and autoimmunity are linked fields. Vaccine efficacy is based on whether host immune response against an antigen can elicit a memory T-cell response over time. Although the described side effects thus far have been mostly transient and acute, vaccines are able to elicit the immune system towards an autoimmune reaction. The diagnosis of a definite autoimmune disease and the occurrence of fatal outcome post-vaccination have been less frequently reported. Since vaccines are given to previously healthy hosts, who may have never developed the disease had they not been immunized, adverse events should be carefully accessed and evaluated even if they represent a limited number of occurrences. In this review of the literature, there is evidence of vaccine-induced autoimmunity and adjuvant-induced autoimmunity in both experimental models as well as human patients. Adjuvants and infectious agents may exert their immune-enhancing effects through various functional activities, encompassed by the adjuvant effect. These mechanisms are shared by different conditions triggered by adjuvants leading to the autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome). In conclusion, there are several case reports of autoimmune diseases following vaccines, however, due to the limited number of cases, the different classifications of symptoms and the long latency period of the diseases, every attempt for an epidemiological study has so far failed to deliver a connection. Despite this, efforts to unveil the connection between the triggering of the immune system by adjuvants and the development of autoimmune conditions should be undertaken. Vaccinomics is a field that may bring to light novel customized, personalized treatment approaches in the future.

What causes alopecia areata?

The pathobiology of alopecia areata (AA), one of the most frequent autoimmune diseases and a major unsolved clinical problem, has intrigued dermatologists, hair biologists and immunologists for decades. Simultaneously, both affected patients and the physicians who take care of them are increasingly frustrated that there is still no fully satisfactory treatment. Much of this frustration results from the fact that the pathobiology of AA remains unclear, and no single AA pathogenesis concept can claim to be universally accepted. In fact, some investigators still harbour doubts whether this even is an autoimmune disease, and the relative importance of CD8(+) T cells, CD4(+) T cells and NKGD2(+) NK or NKT cells and the exact role of genetic factors in AA pathogenesis remain bones of contention. Also, is AA one disease, a spectrum of distinct disease entities or only a response pattern of normal hair follicles to immunologically mediated damage? During the past decade, substantial progress has been made in basic AA-related research, in the development of new models for translationally relevant AA research and in the identification of new therapeutic agents and targets for future AA management. This calls for a re-evaluation and public debate of currently prevalent AA pathobiology concepts. The present Controversies feature takes on this challenge, hoping to attract more skin biologists, immunologists and professional autoimmunity experts to this biologically fascinating and clinically important model disease.

The basic science of hair biology: what are the causal mechanisms for the disordered hair follicle?

A hair disorder can be difficult to define, but patients are typically motivated to seek treatment when their hair growth patterns are significantly different from their cultural group or when growth patterns change significantly. The causes of hair disorders are many and varied, but fundamentally the disorder is a consequence of aberrant alterations of normal hair biology. The potential trigger factors for hair disorders can be attributed to inflammation, genetics, the environment, or hormones, of which the relative contributions vary for different diagnoses, between individuals, and over time. This article discusses the causal mechanisms for the disordered hair follicle.

Etiopathogenesis of alopecia areata: Why do our patients get it?

Alopecia areata (AA) is a nonscarring, inflammatory skin disease that results in patchy hair loss. AA is unpredictable in its onset, severity, and duration making it potentially very stressful for affected individuals. Currently, the treatment options for AA are limited and the efficacy of these treatments varies from patient to patient. The exact etiology of AA is unknown. This article provides some insights into the etiopathogenesis of AA and why some people develop it. The current knowledge on the pathogenesis of AA is summarized and some of the recent hypotheses and studies on AA are presented to allow for a fuller understanding of the possible biological mechanisms of AA.