eISSN: 1644-4124
ISSN: 1426-3912
Central European Journal of Immunology
Current issue Archive Manuscripts accepted About the journal Special Issues Editorial board Abstracting and indexing Subscription Contact Instructions for authors Publication charge Ethical standards and procedures
Editorial System
Submit your Manuscript
SCImago Journal & Country Rank
3/2020
vol. 45
 
Share:
Share:
Review paper

Immunology of alopecia areata

Marta Żeberkiewicz
1
,
Lidia Rudnicka
2
,
Jacek Malejczyk
1

  1. Department of Histology and Embryology, Center for Biostructure Research, Medical University of Warsaw, Warsaw, Poland
  2. Department of Dermatology, Medical University of Warsaw, Warsaw, Poland
Cent Eur J Immunol 2020; 45 (3): 325-333
Online publish date: 2020/11/01
Article file
Get citation
 
PlumX metrics:
 

Introduction

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 of this chronic hair-loss disorder is not fully understood, and the available therapies are symptomatic and not preventing a relapse of the disease [1, 2].

This review focuses on immunology of alopecia areata and defines key characteristics of the pathologic abnormalities of hair follicles. To date, available evidences has been suggesting that alopecia areata is an autoimmune disease, in which the collapse of hair follicles immune privilege may play a crucial role in the pathogenesis [3, 4].

Normal hair growth

Hair follicles undergo lifelong, cyclic transformation [5]. Traditionally, three phases of hair growth were recognized, including anagen, with classification ranging from stages I to VI (a period of very rapid growth, pigmentation, and hair-shaft production), catagen (regression phase), and telogen (resting phase) [5]. This cyclic transformation is controlled by finely tuned changes in the local signaling milieu, based on changes in the expression of cytokines, hormones, neurotransmitters as well as transcription factors and enzymes. The regenerative capacity of hair follicles depends on a group of keratinocyte and melanocyte steam cells that are located in the follicular bulge area [5-7]. It is a convex protrusion of outer root sheath in the most distal permanent portion of hair follicle, just below the sebaceous gland. Regulation of bulge cell activities involves many signaling pathways, such as Wnt/β-catenin, BMP/Smad, and Sonic hedgehog (Shh) signaling [8-10].

Immunobiology of the hair follicle

Decades ago, it was reported that hair follicles establish a special area, which enables transplanted allogeneic cells to escape detection and elimination by the immune system [11]. A creation of relative immune privilege protects from an autoimmune attack on intrafollicularly expressed autoantigens and prevents an immunopathogenic injury [12]. Several mechanisms collaborate in providing immune protection (Table 1). A unique feature of hair follicle immune privilege is that it demonstrates the unusual ability to completely regenerate itself during each anagen phase. Additionally, it is limited only to those parts of the hair follicle epithelium, which are generated from hair follicle steam cells (i.e., hair matrix and inner root sheath) [5, 13].

Table 1

The mechanisms of HF immune privilege

Low number of CD4+ or CD8+ T cells and CD1a+ Langerhans cell in anagen hair bulb. Additionally, Langerhans cells have a reduced MHC class II-dependent antigen presenting capacity bulb [98]
Expression of MHC I in anagen hair bulbs is absent or substantially reduced [99]
Melanocytes of the hair follicle pigmentary unit are MHC I negative [98]
Anagen hair follicles contain very few NK cells and they do not express MICA [46]
Interferon regulatory factor-1 reactivity is significantly down-regulated in the anagen hair matrix (interferon-γ acts as the most important enhancer of MHC I expression via interferon regulatory factor-1) [47]
Anagen hair bulb generates immunosuppressive molecules, such as TGF-β1, TGF-β2, ACTH, and α-MSH [100, 101]
Epithelial hair bulb is unsheathed by a special matrix barrier, which hinder immune cell trafficking [102]

Epidemiology

The lifetime risk of alopecia areata is about 1.7% in the general population. The prevalence of alopecia areata ranges from 0.1% to 0.2% worldwide, depending on the ethnic background [14]. It affects approximately 0.7% to 3.8% of all the patients attending dermatology clinics [15]. The peak incidence of alopecia areata seems to occur among 15 to 29-year-old individuals. Onset of alopecia areata occurs in 44% of patients before their 20s, and less than 30% develop the disease after their 40s [15, 16]. The clinical course is highly unpredictable, and it can occur at any age from birth to the late decades of life.

Clinical features

Most commonly, alopecia areata manifests as a rapid hair loss in small, well-circumscribed patches. The lesions are usually round or oval, with distinctive borders, and normal hair delineating the periphery. The hair loss appears in isolated or several patches, and scalp is the most common site affected by alopecia areata (90%) [17, 18]. The disease may lead to complete baldness (areata totalis) or loss of all body hair (alopecia universalis). Several variants of alopecia areata have been described. Ophiasis clinically manifests as hair loss in the shape of a wave at the circumference of the head. ‘Sudden graying’ is a variant, in which very sudden, overnight graying is caused by preferential loss of pigmented hair. A very rare type is alopecia areata diffusa, characterized by diffuse (non-patchy) hair loss with female predominance [19]. Alopecia areata incognita, with loss of hair primarily in the vertex area, is considered by some authors a subtype of alopecia areata [19]. Spontaneous hair regrowth has been described in individual cases; however, in most cases, long-term immunosuppressive or immunomodulating therapy is required. In alopecia areata, the regrowing hairs are often white, becoming pigmented during growing. In severe forms, hair loss may persist for many years.

Characteristic trichoscopy features that indicate areas of activity are ’exclamation-mark’ hairs (when the distal segment of hair shaft is broader than its proximal end) and ‘black dots’ (hairs that have broken at the scalp surface) [20, 21]. Because alopecia areata is a systemic disorder, it can also affect nails and eyes. Nail changes (beau lines, nail pitting, onychomadesis, onycholysis, trachyonychia, and hemorrhagic spotting of lunula) may be seen in 3-30% of patients [22]. Their involvement is usually associated with severe alopecia areata.

Pathobiology and immunology

The pathobiology of alopecia areata remains unclear. Currently, little is known about risk factors, but various studies have suggested that alopecia areata is a complex multigenetic trait with an inherited predisposition component [23]. Moreover, discordance in identical twins indicated that the disease could be triggered by environmental factors [24]. The majority of cases are sporadic, and the reported frequency of a positive family history varies from 3% to 42% [25, 26].

Alopecia areata is mostly considered to be a cell-mediated autoimmune disease, in which autoreactive cytotoxic T cells recognize melanocyte-associated proteins, such as tyrosinase. On the other hand, some evidences suggest that it is not a truly autoimmune disease but is only ‘consistent with’ autoimmune mechanism [27]. Below we analyze these two hypotheses.

Alopecia areata as an autoimmune disease

Direct and indirect evidences support hypothesis that alopecia areata is a tissue-specific autoimmune disease with a genetic predisposition and an environmental trigger. Recent study shows a higher incidence rate in the female population [28]. The disease is associated with increased risk of other autoimmune disorders (Table 2). Approximately, 12-16% of individuals with alopecia areata develop an autoimmune disease [29, 30].

Table 2

Autoimmune diseases associated with alopecia areata

Autoimmune diseaseReferences
Hashimoto thyroiditis[103]
Vitiligo[104-106]
Systemic lupus erythematosus[26]
Autoimmune thrombocytopenic purpura[107]
Type I (insulin-dependent) diabetes[79]
Myasthenia gravis[105]
Celiac disease[108]
Scleroderma[106]
Ulcerative colitis[105, 106]

Histologic feature of alopecia areata is a lymphocytic infiltrate adjoining the hair follicle site, which may appear in a characteristic “swarm of bees” pattern [31]. This is a result of the collapse of hair follicle immune privilege, with exposure of autoantigens that lead to an accumulation of autoreactive T cells [32]. An infiltration is observed, particularly in the acute stage of the disease. In the accumulation surrounding the hair follicle, CD4+ Th1 cells predominate, while within the follicular epithelium, CD8+ Tc1 cells represent the majority [33]. In the chronic stage, marked hair follicle miniaturization and cell accumulation decrease are observed, but CD8+ Tc1 cells are still present [34].

Round alopecia lesions may reflect a chain autoimmune reaction in adjacent hair follicles induced by T cell and cytokine diffusion [27]. CD8+ T cells can be differentiated into two phenotypes (Fig. 1). Type I - CD8+ cytotoxic T (Tc1) cells secrets IFN-γ and play an essential role in the development of autoimmune diseases, such as autoimmune thyroiditis [35]. A significant number of those cells in skin lesions of alopecia areata contribute to cell-mediated autoimmune reactions. In addition, the proportions of CD4+ Th1 cells and CD8+ Tc1 cells are considerably higher in the peripheral blood mononuclear cells (PBMCs) [36]. These cells display strong chemotactic activity towards CXCL10 [34]. Also, the Th1 chemokines (CXCL9, CXCL10, and CXCL11) are highly expressed in alopecia areata lesions [37]. It has been suggested that improved production of CXCL10 from hair follicles induces preferential infiltration of Th1 and Tc1 cells in the acute phase of alopecia areata, and Tc1 infiltration remains prolonged within the chronic phase [34]. In addition, an overall impairment in the Th1-mediated immune response suggests increased IL-2 and IFN-γ serum levels [38]. IL-2 shows a positive correlation with duration and severity of the disease [38]. Observed efficacy of JAK inhibitors including ruxolitinib, tofacitinib, and baricitinib in the treatment of alopecia areata appears to be secondary to the disruption of Th1 immune response and elimination of IFN-γ effect [39, 40]. Preclinical studies have also shown that abatacept, a recombinant fusion protein (CTLA4-Ig) is effective in preventing the disease in mouse model [41]. Abatacept blocks the potential co-stimulatory interaction with antigen-presenting cells/APC, a process required for full T cell activation.

Fig. 1

Effector CD8+T cells can be segregated into two populations on the basis of the cytokines they secrete similar to CD4+ T cells. Tc1 cells characteristically produce type-1 cytokines (IL-2, TNF-α, and IFN-γ), whereas Tc2 cells secrete type-2 cytokines (IL-4, IL-5, IL-6, IL-10, and IL-13). Tc1 cells as well as Th1 cells are involved in the protection against intracellular parasites and delayed-type hypersensitivity, but also, they play an important role in autoimmunity. Autoimmune diseases are characterized by increased Tc1/Tc2 ratio, in the same way as Th1/Th2 ratio

/f/fulltexts/CEJOI/42550/CEJI-45-42550-g001_min.jpg

Hair follicle is a site of immune privilege [11]. Immunoprotection is limited to the anagen, sequesters melanogenesis, and other anagen-associated antigens of immune recognition [42]. In catagen, the hair follicle regresses, and involves apoptosis and remodeling of the transient portion [43]. Immune cells infiltrate around catagen-stage hair follicles [44]. This process cyclically exposes the immune system to low levels of hair follicle’s antigens. If catagen regression became disordered, inappropriate expression of stimulatory antigen to the immune system might breach the threshold for the onset of overt alopecia areata [45]. Many hypotheses for autoimmunity onset in alopecia areata have been reported [27]. The most widely accepted is the immune privilege collapse theory [42]. It postulates that the disease occurs only when key events coincide (Fig. 2) [12].

Fig. 2

Proposed pathogenesis of alopecia areata. The immunosuppressive milieu of the anagen hair bulb is modulated by immunosuppressive factors, such as α-MSH, TGF-β, and IGF-1, and suppressing NK-cells. Alopecia areata is hair follicle response pattern to various inflammatory events associated with e.g., IFN-γ-induced up-regulation of expression of MHC class Ia inside the hair follicle. Anagen-associated autoantigens are recognized, once they become exposed by ectopic MHC class I. That leads to autoimmune reactions against hair follicle

/f/fulltexts/CEJOI/42550/CEJI-45-42550-g002_min.jpg

MHC class I-negative hair follicles are protected from NK cell attack by MICA-negative outer root sheath, low expression of NKG2D on NK cells, and inhibitory KIRs. In alopecia areata, NKG2D+ NK cells attack MICApositive hair follicles, which results in apoptosis and hair loss [46]. Also, the number of NK cells that express NK cell-inhibitory KIR2DL2 and KIR2DL3 is significantly decreased in patients [46].

Locally generated immunosuppressants (e.g., α-MSH, TGF-β1, and IGF-1) [47] and NK cellsuppressing activities (e.g. MIF expression) [48] provide hair follicle immune privilege. Insufficient activity of these agents predisposes towards development of alopecia areata [12]. Inflammatory cytokines, including substance P and IFN-γ, lead to the collapse of immune privilege by upregulation of expression of MHC class Ia inside the hair follicle. IFN-γ is associated with a Th1 cellular infiltrate and Tc1 cells are the main source. In addition, alopecia areata can sometimes be triggered or exacerbated by viral infections that cause excess secretion of interferons (IFN) [49, 50]. The background of autoimmunity is molecular mimicry and epitope spreading [51]. Also, systemic treatment with interferon-alfa has been linked to the exacerbation or onset of patchy alopecia areata [52, 53], and type 1 interferon--related proteins are overexpressed in the inflammatory lesions [54]. Moreover, TNF-α level is significantly elevated both in lesional and non-lesional skin biopsies of patients [55].

Another concept is the role of IL-17-producing cells. T helper 17 cells have been characterized as a novel subset of CD4+ T cells that produce IL-17A, IL-17F, and IL-22. They are involved in the pathogenesis of autoimmune diseases [56]. Elevated IL-17 levels were found in rheumatoid arthritis, systemic lupus erythematosus, and psoriasis [57]. Recent reports suggest the contribution of IL-17 to the development of alopecia areata. IL17RA gene polymorphism is associated with increased susceptibility to alopecia areata [58]. Additionally, Th17 cells are present in affected lesions, particularly around hair follicles [59]. A study suggests that the contribution of IL-17-producing cells is even stronger than that of IFN-γ-producing cells in the pathogenesis [60]. These cells might enhance the local inflammation in combination with decreasing T reg cells in the affected skin of alopecia areata. Interestingly, the ratio of IL-17-producing cells in acute, diffuse, and total alopecia is significantly lower than in multiple patchy types of alopecia areata [60]. Therefore, the ratio of IL-17-producing cells in the lesional skin might be connected with clinical types of the disease. Denser Th17 cells infiltration is associated with more severe symptoms in comparison with a longer duration of the disease [61], which may be explained by long survival of Th17 cells in chronic inflammation. Cytokine that plays a role in the in the maintenance of Th17 response is IL-23. At the moment, three agents that block IL-17 are investigated, including secukinumab, brodalumab, and ixekizumab [62]. However, most of mentioned evidences to support the role of IL-17-producing cells in alopecia areata are not strong (see below).

Antibodies can be found in abundance in alopecia areata, sometimes in extremely high titers. These alopecia areata antibodies are useful in search for target antigens. They react with multiple components of anagen hair follicles [63, 64]. It is known that alopecia areata almost solely attacks growing (anagen) hair follicles that engage in active melanogenesis [65]. Pigmented hair follicles are selectively lost in active disease, whereas regrowing hair are frequently white. Alopecia areata is also often associated with vitiligo [63, 66]. These observations suggest involvement of melanogenesis-associated autoantigens. In addition, follicular melanocytes show histological abnormalities and in some affected hair bulb are completely deleted [11]. Finally, in a late stage of alopecia areata, epitope spreading occurs, developing from autoantibodies to innumerable epitopes [67]. Another suggested mechanism is an immune response against a variety of hair keratins [68].

Autoimmunity in alopecia areata is strongly supported by effectiveness of immunosuppressive agents. Good response is achieved with allergic contact sensitizers (e.g., diphenylcyclopropenone), which are applied to achieve low-grade chronic dermatitis [69]. Their mechanism of action probably include diversion of the T cell response from the hair follicle to epidermis, and induction of localized immunosuppression by production of immunosuppressive cytokines (e.g., TGF-β, IL-10, and myeloid-derived suppressor cell) [70, 71]. Benefit for the treatment may provide also other immunosuppressive agents, especially systemic corticosteroids and cyclosporine [72]. The newest idea for the alopecia areata therapy is application of JAK inhibitors, such as ruxolitinib and tofacitinib [73, 74]. Systemic and topical administration was highly effective in reversing disease and associated with a markedly reduced proportion of CD8+ NKG2D+ cells.

Alopecia areata as not a truly autoimmune disease

The characteristics of alopecia areata vary from those seen in classical autoimmune diseases. In contrast to other autoimmune diseases, when women are affected three times more than men, a study report equal frequency in both sexes [75]. The peak prevalence occurs at the age of 20, but it can affect patients at any age [76]. The fact that the concordance rate in monozygotic twins is not 100% indicate a complex nature of the disease, involving both genetic and environmental triggers [77]. In addition, literature indicates that coincidence of other autoimmune diseases does not differ significantly [78]. For example, frequency of type 1 diabetes mellitus is reduced in patients, but significantly increased in their relatives [79].

The mononuclear cell infiltrate around the terminal hair bulb is believed to be the classic finding in the early (acute) stage of alopecia areata [80]. However, this infiltrate is found in only one-third of patients, which are initially present with alopecic patches. Furthermore, immune cells are commonly absent in biopsies taken at a later stage [80] and in areas of severe follicular damage [63]. Accepting the disease targets is a hair follicle-associated antigen, and patients should have an abundance of lesions, such as in alopecia totalis or universalis, not single, circumscribed patches. Additionally, there are long periods of complete clinical remission that are not pathognomonic for autoimmune diseases [27].

Administration of IFN-γ has previously been suggested to promote a collapse of hair follicle immune privilege that may initiate inflammatory lesions in alopecia areata [81]. Unfortunately, some laboratories report that the occurrence of alopecia areata after IFN-γ injections did not changed the frequency [82]. It shows that although hair follicle immune privilege collapse may be required to initiate disorder, additional factors are also needed. Several immune privilege genes are downregulated in perilesional and lesional hair follicles [83]. They suggest that aberration in hair follicle immune privilege is not sufficient to initiate the disease.

A concept that melanogenesis-related proteins are the source of initiating epitopes is the most widely accepted. Unfortunately, observations supporting this thesis are based on data obtained from patients with clinically established disorder, not at the time of initiation. The antigen targeted at the time of alopecia areata onset may not be the same as the epitope to perpetuate hair loss in chronic disease. Moreover, alopecia areata may occur in albino strains of mice [84]. Although they are unable to produce ultimate melanin pigments, the biochemical pathway to produce melanin, including melanosomes, is normal. This data suggest that melanin-related proteins are not the inciting epitope, but they may occur later. Additional unresolved question is the role of hair follicle autoantibodies. Failure to inhibit hair growth in human scalp skin, grafted onto nude mice by passive transfer of autoantibodies from affected individual suggest that they are not always the key pathogenic factor [85]. Autoantibodies against a variety of hair keratins can be also found, to various degrees, in clinically normal patients [68, 86]. There is no consistent correlation between the development of these autoantibodies and the onset of alopecia areata.

Environmental insults, such as infection, contribute to autoimmunity and they have been discussed as possible trigger factors. However, the association of cytomegalovirus (CMV) has been refused [24]. The detection of CMV DNA sequences in skin biopsies seems to be an incidental finding. Similarly, other viruses, including hepatitis B (HBV), hepatitis C virus (HCV), or even vaccinations have been suggested to trigger alopecia areata [87, 88]. A study with C3H/HeJ mouse model for adult onset alopecia areata indicated no effect of the vaccine [89].

The beneficial response to immunosuppression therapies implies an autoimmune mechanism. However, many inflammatory diseases also benefit from immunosuppression, so this fact should not be considered alone as evidence of an autoimmune etiology. Although, new biological drugs are effective therapies for numerous autoimmune diseases in alopecia areata, no significant efficacy was shown and some studies report on aggravation during therapy [90, 91]. This paradoxical side effect could occur because of the fact that down-regulation of TNF-α may up-regulate IFN-γ [92].

Conclusions

Alopecia areata is a recurrent form of non-scarring hair loss. Over the last two centuries, many hypotheses have been proposed to explain pathogenesis, none of which have been proven so far. Most authors tend to classify alopecia areata as an autoimmune disease [93]. However, this concept in only supported by circumstantial evidence, and no theory is accepted in general. This is especially true when considering Witebsky’s postulates [94]. Autoantibodies to hair follicle-associated antigens occur in normal individuals, and no specific follicular epitope has been identified as responsible for triggering alopecia areata. Until the antigen is found, the autoimmune concept still remains a hypothesis. Several other theories are occasionally revisited in the medical literature. For example, recent studies emphasized the importance of genetic factors [23, 27, 95]. Psoriasis, which is also suggested to be an autoimmune-mediated disease, has a strong genetic basis. The genome-wide association studies have clearly implicated the role of both innate and adaptive immune systems in the pathogenesis of the disease. There are also multiple reports of alopecia areata development in recipients of allogeneic bone marrow transplantation from affected HLA-matched donors [96, 97]. All these data suggest that alopecia areata has a strong immune component, although other factors may play a role in a disease etiology. Furthermore, in different subsets of alopecia areata, autoimmune, genetic, and infectious factors come together with a different weight in triggering the pathology. Further studies should be performed in patient groups with documented subtypes of alopecia areata to elucidate the underlying mechanisms of pathways involved in pathogenesis of alopecia areata.

Notes

[1] Conflicts of interest The authors declare no conflict of interest.

References

1 

Harries MJ, Sun J, Paus R, et al. (2010): Management of alopecia areata. BMJ 341: c3671.

2 

Alkhalifah A, Alsantali A, Wang E, et al. (2010): Alopecia areata update: part II. Treatment. J Am Acad Dermatol 62: 191-202.

3 

Gilhar A, Ullmann Y, Berkutzki T, et al. (1998): Autoimmune hair loss (alopecia areata) transferred by T lymphocytes to human scalp explants on SCID mice. J Clin Invest 101: 62-67.

4 

Gilhar A, Paus R, Kalish RS (2007): Lymphocytes, neuropeptides, and genes involved in alopecia areata. J Clin Invest 117: 2019-2027.

5 

Paus R, Cotsarelis G (1999): The biology of hair follicles. N Engl J Med 341: 491-497.

6 

Al-Refu K (2012): Stem cells and alopecia: a review of pathogenesis. Br J Dermatol 167: 479-484.

7 

Tobin DJ (2011): The cell biology of human hair follicle pigmentation. Pigment Cell Melanoma Res 24: 75-88.

8 

Kobielak K, Stokes N, de la Cruz J, et al. (2007): Loss of a quiescent niche but not follicle stem cells in the absence of bone morphogenetic protein signaling. Proc Natl Acad Sci U S A 104: 10063-10068.

9 

Plikus MV, Baker RE, Chen CC, et al. (2011): Self-organizing and stochastic behaviors during the regeneration of hair stem cells. Science 332: 586-589.

10 

Paladini RD, Saleh J, Qian C, et al. (2005): Modulation of hair growth with small molecule agonists of the hedgehog signaling pathway. J Invest Dermatol 125: 638-646.

11 

Billingham RE, Silvers WK (1971): A biologist’s reflections on dermatology. J Invest Dermatol 57: 227-240.

12 

Paus R, Nickoloff BJ, Ito T (2005): A ‘hairy’ privilege. Trends Immunol 26: 32-40.

13 

Cotsarelis G, Millar SE (2001): Towards a molecular understanding of hair loss and its treatment. Trends Mol Med 7: 293-301.

14 

Safavi K (1992): Prevalence of alopecia areata in the First National Health and Nutrition Examination Survey. Arch Dermatol 128: 702.

15 

Jabbari A, Petukhova L, Cabral RM, et al. (2013): Genetic basis of alopecia areata: a roadmap for translational research. Dermatol Clin 31: 109-117.

16 

Gilhar A, Etzioni A, Paus R (2012): Alopecia areata. N Engl J Med 366: 1515-1525.

17 

Dawber RP, de Berker DA. Disorders of Hair. Blackwell Science, Boston 1998.

18 

Tan E, Tay YK, Goh Ch L, et al. (2002): The pattern of alopecia areata in Singapore–a study of 219 Asians. Int J Dermatol 41: 748-753.

19 

Inui S, Nakajima T, Itami S (2008): Significance of dermoscopy in acute diffuse and total alopecia of the female scalp: Review of twenty cases. Dermatology 217: 333-336.

20 

Mubki T, Rudnicka L, Olszewska M, et al. (2014): Evaluation and diagnosis of the hair loss patient Part I. Part I. History and clinical examination. J Am Acad Dermatol 71: 415.e1-415.e15.

21 

Mubki T, Rudnicka L, Olszewska M, et al. (2014): Evaluation and diagnosis of the hair loss patient Part II. Trichoscopic and laboratory evaluations. J Am Acad Dermatol 71: 431.e1-431.e11.

22 

Mane M, Nath AK, Thappa DM (2011): Utility of dermoscopy in alopecia areata. Indian J Dermatol 56: 407-411.

23 

Martinez-Mir A, Zlotogorski A, Gordon D, et al. (2007): Genomewide scan for linkage reveals evidence of several susceptibility loci for alopecia areata. Am J Hum Genet 80: 316-328.

24 

Jackow C, Puffer N, Hordinsky M, et al. (1998): Alopecia areata and cytomegalovirus infection in twins: genes versus environment. J Am Acad Dermatol 38: 418-425.

25 

McDonagh AJ, Tazi-Ahnini R (2002): Epidemiology and genetics of alopecia areata. Clin Exp Dermatol 27: 405-409.

26 

Goh C, Finkel M, Christos PJ, et al. (2006): Profile of 513 patients with alopecia areata: associations of disease subtypes with atopy, autoimmune disease and positive family history. J Eur Acad Dermatol Venereol 20: 1055-1060.

27 

McElwee KJ, Gilhar A, Tobin DJ, et al. (2013): What causes alopecia areata? Exp Dermatol 22: 609-626.

28 

Wu MC, Yang CC, Tsai RY, et al. (2013): Late-onset alopecia areata: A retrospective study of 73 patients from Taiwan. J Eur Acad Dermatol Venereol 27: 468-472.

29 

Barahmani N, Schabath MB, Duvic M (2009): History of atopy or autoimmunity increases risk of alopecia areata. J Am Acad Dermatol 61: 581-591.

30 

Chu SY, Chen YJ, Tseng WC, et al. (2011): Comorbidity profiles among patients with alopecia areata: the importance of onset age, a nationwide population-based study. J Am Acad Dermatol 65: 949-656.

31 

Sperling, LC, Lupton GP (1995): Histopathology of nonscarring alopecia. J Cutan Pathol 22: 97-114.

32 

Weedon D (2002): Diseases of cutaneous appendages. In: Weedon’s Skin Pathology. Weedon D (ed.). Churchill Livingstone, London, UK.

33 

Todes-Taylor N, Turner R, Wood GS, et al. (1984): T cell subpopulations in alopecia areata. J Am Acad Dermatol 11: 216-223.

34 

Kuwano Y, Fujimoto M, Watanabe R, et al. (2007): Serum chemokine profiles in patients with alopecia areata. Br J Dermatol 157: 466-473.

35 

Brazillet MP, Batteux F, Abehsira-Amar O, et al. (1999): Induction of experimental autoimmune thyroiditis by heat-denatured porcine thyroglobulin: a Tc1-mediated disease. Eur J Immunol 29: 1342-1352.

36 

Colon EA, Popkin MK, Callies AL, et al. (1991): Lifetime prevalence of psychiatric disorders in patients with alopecia areata. Compr Psychiatry 32: 245-251.

37 

Dai Z, Xing L, Cerise J, et al. (2016): CXCR3 Blockade Inhibits T-cell Migration into the Skin and Prevents Development of Alopecia Areata. J Immunol 197: 1089-1099.

38 

Tembhre MK, Sharma VK (2013): T-helper and regulatory T-cell cytokines in the peripheral blood of patients with active alopecia areata. Br J Dermatol 169: 543-548.

39 

Craiglow BG, King BA (2014): Killing Two Birds with One Stone: Oral Tofacitinib Reverses Alopecia Universalis in a Patient with Plaque Psoriasis. J Invest Dermatol 134: 2988-2990.

40 

Jabbari A, Dai Z, Xing L, et al. (2015): Reversal of alopecia areata following treatment with the JAK1/2 inhibitor baricitinib. EBioMedicine 2: 351-355.

41 

Petukhova L, Cabral RM, Mackay-Wiggan J, et al. (2011): The genetics of alopecia areata: what’s new and how will it help our patients? Dermatol Ther 24: 326-336.

42 

Paus R, Slominski A, Czarnetzki BM (1994): Is alopecia areata an autoimmune-response against melanogenesis-related proteins, exposed by abnormal MHC class I expression in the anagen hair bulb? Yale J Biol Med 66: 541-554.

43 

Botchkareva NV, Ahluwalia G, Shander D (2006): Apoptosis in the hair follicle. J Invest Dermatol 126: 258-264.

44 

Lindner G, Botchkarev VA, Botchkareva NV, et al. (1997): Analysis of apoptosis during hair follicle regression (catagen). Am J Pathol 151: 1601-1617.

45 

Lu W, Shapiro J, Yu M, et al. (2006): Alopecia areata: pathogenesis and potential for therapy. Expert Rev Mol Med 8: 1-19.

46 

Ito T, Ito N, Saatoff M, et al. (2008): Maintenance of hair follicle immune privilege is linked to prevention of NK cell attack. J Invest Dermatol 128: 1196-1206.

47 

Ito T, Ito N, Bettermann A, et al. (2004): Collapse and restoration of MHC class–I–dependent immune privilege: exploiting the human hair follicle as a model. Am J Pathol 164: 623-634.

48 

Ito T, Saathoff M, Nickoloff BJ, et al. (2005): Novel aspects of hair follicle immune privilege and their relevance to alopecia areata. J Invest Dermatol 124: A103.

49 

Ito T, Tokura Y (2012): Alopecia areata triggered or exacerbated by swine flu virus infection. J Dermatol 39: 863-864.

50 

Pender MP (2012): CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis. Autoimmune Dis 2012: 189096.

51 

Ercolini AM, Miller SD (2009): The role of infections in autoimmune disease. Clin Exp Immunol 155: 1-15.

52 

Goh C (2013): Hepatitis C treatment and alopecia totalis. J Investig Dermatol Symp Proc 16: S59-60.

53 

Radny P, Bauer J, Caroli UM, et al. (2004): Alopecia areata induced by adjuvant treatment with alpha-interferon in malignant melanoma? Dermatology 209: 249-250.

54 

Ghoreishi M, Martinka M, Dutz JP (2010): Type 1 interferon signature in the scalp lesions of alopecia areata. Br J Dermatol 163: 57-62.

55 

Gohary YM, Abdel Fattah DS (2017): Detection of Tumor Necrosis Factor-alpha in Nonlesional Tissues of Alopecia Areata Patients: A Prove for a Systemic Disease. Int J Trichology 9: 154-159.

56 

Bettelli E, Oukka M, Kuchroo VK (2007): T(H)-17 cells in the circle of immunity and autoimmunity. Nat Immunol 8: 345-350.

57 

Yu JJ, Gaffen SL (2008): Interleukin-17: a novel inflammatory cytokine that bridges innate and adaptive immunity. Front Biosci 13: 170-177.

58 

Lew BL, Cho HR, Haw S, et al. (2012): Association between IL17A/IL17RA Gene Polymorphisms and Susceptibility to Alopecia Areata in the Korean Population. Ann Dermatol 24: 61-65.

59 

Tanemura A, Oiso N, Nakano M, et al. (2013): Alopecia areata: infiltration of Th17 cells in the dermis, particularly around hair follicles. Dermatology 226: 333-336.

60 

Tojo G, Fujimura T, Kawano M, et al. (2013): Comparison of interleukin-17-producing cells in different clinical types of alopecia areata. Dermatology 227: 78-82.

61 

Hong JW, Lee CY, Ha SM, et al. (2017): The Contributory Roles of Th17 Lymphocyte and Cytotoxic T Lymphocyte at the Hair Bulge Region as Well as the Hair Bulb Area in the Chronic Alopecia Areata Patients. Ann Dermatol 29: 156-166.

62 

Wasilewska A, Winiarska M, Olszewska M, et al. (2016): Interleukin-17 inhibitors. A new era in treatment of psoriasis and other skin diseases. Adv Dermatol Allergol 33: 247-252.

63 

Tobin DJ (1997): Morphological analysis of hair follicles in alopecia areata. Microsc Res Tech 38: 443-451.

64 

Tobin DJ (2003): Characterization of hair follicle antigens targeted by the anti-hair follicle immune response. J Investig Dermatol Symp Proc 8: 176-181.

65 

McDonagh AJ, Messenger AG (1996): The pathogenesis of alopecia areata. Dermatol Clin 14: 661-670.

66 

Nagai H, Oniki S, Oka M, et al. (2006): Induction of cellular immunity against hair follicle melanocyte causes alopecia. Arch Dermatol Res 298: 131-134.

67 

Gilhar A, Landau M, Assy B, et al. (2001): Melanocyte-Associated T Cell Epitopes Can Function as Autoantigens for Transfer of Alopecia areata to Human Scalp Explants on Prkdcscid Mice. J Invest Dermatol 117: 1357-1362.

68 

Tobin DJ, Orentreich N, Fenton DA (1994): Antibodies to hair follicles in alopecia areata. J Invest Dermatol 102: 721-724.

69 

Happle R (2002): Diphencyprone for the treatment of alopecia areata: more data and new aspects. Arch Dermatol 138: 112-123.

70 

Gupta P, Freyschmidt-Paul P, Vitacolonna M, et al. (2006): A chronic contact eczema impedes migration of antigen-presenting cells in alopecia areata. J Invest Dermatol 126: 1559-1573.

71 

Marhaba R, Vitacolonna M, Hildebrand D, et al. (2007): The importance of myeloid-derived suppressor cells in the regulation of autoimmune effector cells by a chronic contact eczema. J Immunol 15; 179: 5071-5081.

72 

Miteva M, Tosti A (2012): Treatment options for alopecia: an update, looking to the future. Expert Opin Pharmacother 13: 1271-1281.

73 

Xing L, Dai Z, Jabbari A, et al. (2014): Alopecia areata is driven by cytotoxic T lymphocytes and is reversed by JAK inhibition. Nat Med 20: 1043-1049.

74 

Park HS, Kim MW, Lee JS, et al. (2017): Oral tofacitinib monotherapy in Korean patients with refractory moderate-to-severe alopecia areata: A case series. J Am Acad Dermatol 77: 978-980.

75 

Alzolibani AA (2011): Epidemiologic and genetic characteristics of alopecia areata (part 1). Acta Dermatovenerol Alp Pannonica Adriat 20: 191-198.

76 

Wasserman D, Guzman-Sanchez DA, Scott K, et al. (2007): Alopecia areata. Int J Dermatol 46: 121-131.

77 

Rodriguez TA, Fernandes KE, Dresser KL, et al. (2010): Concordance rate of alopecia areata in identical twins supports both genetic and environmental factors. J Am Acad Dermatol 62: 525-527.

78 

Korkij W, Soltani K, Simjee S, et al. (1984): Tissue specific autoantibodies and autoimmune disorders in vitiligo and alopecia areata: A retrospective study. J Cutan Pathol 11: 522-530.

79 

Wang SJ, Shohat T, Vadheim C, et al. (1994): Increased risk for type I insulin-dependent diabetes in relatives of patients with alopecia areata (AA). Am J Med Genet 51: 234-239.

80 

Whiting DA (2003): Histopathologic features of alopecia areata: a new look. Arch Dermatol 139: 1555-1559.

81 

Gilhar A, Kam Y, Assy B, et al. (2005): Alopecia areata induced in C3H/HeJ mice by interferon-gamma: evidence for loss of immune privilege. J Invest Dermatol 124: 288-289.

82 

Sundberg JP, Silva KA, Edwards K (2007): Failure to induce alopecia areata in C3H/HeJ mice with exogenous interferon gamma. J Exp Anim Sci 43: 265-270.

83 

Kang H, Wu WY, Lo BK, et al. (2010): Hair follicles from alopecia areata patients exhibit alterations in immune privilege-associated gene expression in advance of hair loss. J Invest Dermatol 130: 2677-2680.

84 

McElwee KJ, Boggess D, Miller J, et al. (1999): Spontaneous alopecia areata-like hair loss in one congenic and seven inbred laboratory mouse strains. J Investig Dermatol Symp Proc 4: 202-206.

85 

Gilhar A, Pillar T, Assy B, et al. (1992): Failure of passive transfer of serum from patients with alopecia areata and alopecia universalis to inhibit hair growth in transplants of human scalp skin grafted on to nude mice. Br J Dermatol 126: 166-171.

86 

Tobin DJ, Bystryn JC (1995): Immunity to hair follicles in alopecia areata. J Invest Dermatol 104: 13S-14S.

87 

Podányi B, Lengyel G, Hársing J, et al. (1998): Skin diseases associated with chronic hepatitis C. Orv Hetil 139: 2633-2637.

88 

Italian Group of Epidemiological Studies in Dermatology (1990): Study of lichen planus conducted by the IGESD: results, implications for clinical practice, prospects. G Ital Dermatol Venereol 125: 563-567.

89 

Sundberg JP, Silva KA, Zhang W, et al. (2009): Recombinant human hepatitis B vaccine initiating alopecia areata: testing the hypothesis using the C3H/HeJ mouse model. Vet Dermatol 20: 99-104.

90 

Price VH, Hordinsky MK, Olsen EA, et al. (2008): Subcutaneous efalizumab is not effective in the treatment of alopecia areata. J Am Acad Dermatol 58: 395-402.

91 

Abramovits W, Losornio M (2006): Failure of two TNF-αlpha blockers to influence the course of alopecia areata. Skinmed 5: 177-181.

92 

Palucka AK, Blanck JP, Bennett L, et al. (2005): Cross-regulation of TNF and IFN-alpha in autoimmune diseases. Proc Natl Acad Sci U S A 102: 3372-3377.

93 

Kalish RS, Gilhar A (2003): Alopecia areata: autoimmunity--the evidence is compelling. J Investig Dermatol Symp Proc 8: 164-167.

94 

Rose NR, Bona C (1993): Defining criteria for autoimmune diseases (Witebsky’s postulates revisited). Immunol Today 14: 426-430.

95 

Petukhova L, Duvic M, Hordinsky M, et al. (2010): Genome-wide association study in alopecia areata implicates both innate and adaptive immunity. Nature 466: 113-117.

96 

Barahmani N, Whaley K, Duvic M (2003): Alopecia areata after allogeneic bone marrow transplantation from an affected, human leukocyte antigen-matched sibling. J Am Acad Dermatol 49: 1192.

97 

Nadeem S, Hymes S, Kebriaei P, et al. (2014): Alopecia areata after HLA-identical BMT from an affected, sibling donor. Bone Marrow Transplant 49: 592-594.

98 

Moseley RP, Brown JI, Auld J, et al. (1997): An imunocytochemical study of MHC class I expression on human Langerhans cells and melanocytes. J Pathol 181: 419-425.

99 

Ito T (2013): Recent Advances in the Pathogenesis of Autoimmune Hair Loss Disease Alopecia Areata. Clin Dev Immunol 2013: 348546.

100 

Welker P, Foitzik K, Bulfone-Paus S, et al. (1997): Hair cycle-dependent changes in the gene expression and protein content of transforming factor beta 1 and beta 3 in murine skin. Arch Dermatol Res 289: 554-557.

101 

Kono M, Nagata H, Umemura S, et al. (2001): In situ expression of corticotropin-releasing hormone (CRH) and proopiomelanocortin (POMC) genes in human skin. EMBO J 15: 2297-2299.

102 

Stenn KS, Paus R (2001): Control of hair follicle cycling. Physiol Rev 81: 449-494.

103 

Kurtev A, Iliev E (2005): Thyroid autoimmunity in children and adolescents with alopecia areata. Int J Dermatol 44: 457-461.

104 

Kuchabal SD, Kuchabal DS (2010): Alopecia areata associated with localized vitiligo. Case Rep Dermatol 2: 27-31.

105 

Tan RS (1974): Ulcerative colitis, myasthenia gravis, atypical lichen planus, alopecia areata, vitiligo. Proc R Soc Med 67: 195-196.

106 

Thompson DM, Robinson TW, Lennard-Jones J (1974): Alopecia areata, vitiligo, scleroderma and ulcerative colitis. Proc R Soc Med 67: 1010-1012.

107 

Ahmed AM, Barahmani N, Duvic M (2008): National Alopecia Areata Registry. Familial alopecia areata and chronic thrombocytopenia. J Am Acad Dermatol 58: S75-77.

108 

Ertekin V, Tosun MS, Erdem T (2014): Screening of Celiac Disease in Children with Alopecia areata. Indian J Dermatol 59: 317.

Copyright: © 2020 Polish Society of Experimental and Clinical Immunology This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License (http://creativecommons.org/licenses/by-nc-sa/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.
 
Quick links
© 2024 Termedia Sp. z o.o.
Developed by Bentus.