A proposed mechanism for central centrifugal cicatricial alopecia

Updates on disorders in curly hair

Hair disorders, including central centrifugal cicatricial alopecia (CCCA), traction alopecia (TA), and acquired trichorrhexis nodosa (ATN), commonly occur in individuals with curly textured hair. Curly textured hair in individuals of African descent has unique properties and can present diagnostic and therapeutic challenges. CCCA has been linked to uterine leiomyoma and type 2 diabetes mellitus, as well as fibroproliferation. TA often presents with a fringe sign and can arise from high-tension hairstyles presumed to be protective. Trichoscopy is useful in establishing a diagnosis; perifollicular halos are more commonly seen than perifollicular erythema or scale in CCCA. In TA, miniaturized follicles, hair casts, and "flambeau sign" can be seen. Hairstyling practices likely contribute to TA and ATN; however, the data are mixed on the role of chemical relaxers and heat styling in CCCA. Unique considerations in the presentation of frontal fibrosing alopecia in curly textured hair have also been published recently. This review provides a comprehensive, up-to-date summary of these disorders with an emphasis on their unique properties, as well as considerations in hair care for curly textured hair.

Quantification of mast cells in central centrifugal cicatricial alopecia

Background

Mast cells (MCs) have recently been implicated in lymphocytic scarring alopecias, which may share a common pathogenesis. MCs in central centrifugal cicatricial alopecia (CCCA) have not been studied.

Objective

We looked for the presence of MCs in CCCA using 2 different stains to see if their numbers correlated with the number of hair follicles, the degree of inflammation and perifollicular fibrosis, disease duration and severity, and patient symptoms.

Methods

We performed a retrospective review of biopsies of patients diagnosed with CCCA, tabulated MC counts and correlated them with histopathologic and clinical findings.

Results

MC counts were significantly greater using immunoperoxidase staining with CD117 than Giemsa stain, and more were present when the isthmus level was included with the infundibulum. MC counts with CD117 immunostain significantly correlated with the degree of inflammation. MC counts with both stains were significantly associated with the degree of fibrosis independently and after controlling for other factors.

Limitations

The study was limited by insufficient tissue remaining in a small number of the transversely cut blocks.

Conclusion

Our findings may have therapeutic implications for CCCA and other types of lymphocytic scarring alopecia.

Central centrifugal cicatricial alopecia: a deeper insight into the disease

Central centrifugal cicatricial alopecia (CCCA) is a scarring alopecia of multifactorial etiology that presents on the vertex as patchy areas of hair loss, spreading centrifugally over the scalp. It most commonly affects women of African descent, but cases among other ethnicities have also been reported. CCCA typically starts with thinning and breaking of the hair as the first sign of presentation, which eventually progresses to hair loss over the central part of the scalp, spreading symmetrically outwards to involve a larger area. Currently, there is no definitive cure for the disease; however, multiple management options are available, which should aim to be tailored to the individual patient. Owing to its cosmetic outcomes, the quality of life (QoL) of patients with central centrifugal cicatricial alopecia is also disturbed, as patients may face psychological and social stress due to their permanent hair loss. This article focuses on various aspects of the pathogenesis, clinical trials, quality of life, barriers faced by patients, and treatment of central centrifugal cicatricial alopecia.

Deimination in epidermal barrier and hair formation

Peptidylarginine deiminases (PADs) transform a protein arginine residue into the non-standard amino acid citrulline. This calcium-dependent post-translational modification of proteins is called citrullination or deimination. As described in this special issue, PADs play a role in various physiological processes, and PAD deregulations are involved in many human diseases. Three PADs are expressed in the epidermis, where their roles begin to be deciphered. PAD1 and PAD3 are involved in keratinocyte differentiation, particularly in the epidermal barrier function, keratins, filaggrin and filaggrin-related proteins being the most abundant deiminated epidermal proteins. Reduced amounts of deiminated proteins and PAD1 expression may be involved in the pathogenesis of psoriasis and atopic dermatitis, two very frequent and chronic skin inflammatory diseases. The trichohyalin/PAD3/transglutaminase three pathway is important for hair shaft formation. Mutations of the PADI3 gene, leading to a decreased activity or abnormal localization of the corresponding isotype, are the cause of a rare hair disorder called uncombable hair syndrome, and are associated with the central centrifugal cicatricial alopecia, a frequent alopecia mainly affecting women of African ancestry. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

Risk factors and comorbidities associated with central centrifugal cicatricial alopecia

Central centrifugal cicatricial alopecia (CCCA) is the most common form of scarring alopecia that most often affects Black women. The disease typically begins with hair loss in the center scalp, which progresses in a centripetal fashion. Both environmental insult and genetics have been implicated in CCCA etiology, although the exact pathophysiology remains unknown. Nevertheless, it is important that providers feel comfortable educating their patients on risk factors (RFs) for the development or worsening of CCCA, and potential comorbidities associated with the condition. Thus, the goal of this review was to summarize these factors. A comprehensive literature search was performed, and studies were included if they reported research on RFs for or comorbidities associated with, CCCA. A total of 15 studies were included: n = 5 researching RFs for CCCA and n = 10 researching comorbidities associated with CCCA. There was an association suggesting an increased risk of CCCA with traction hairstyles in n = 2/3 studies, previous pregnancies in n = 1/1 studies, and use of chemical hair relaxers in n = 1/3 studies. Additionally, age and total years of hair loss were associated with increased CCCA severity in n = 2/2 studies. Type 2 diabetes was positively associated with CCCA in n = 3/5 studies, uterine leiomyomas in n = 1/2 studies, hyperlipidemia in n = 1/2 studies, and vitamin D deficiency in n = 1/1 studies. Conflicting results regarding RFs and comorbidities associated with CCCA exist within the literature. Thus, further investigation in larger cohorts must be done, and future research into genes implicated in CCCA and their potential role in the development of other diseases is recommended.

Central Centrifugal Cicatricial Alopecia Associated With PDL1 Loss and Increased Expression of Caspase 3: A Case Series

ABSTRACT

Central centrifugal cicatricial alopecia (CCCA) is a scarring alopecia that disproportionately affects patients with skin of color. Genetic studies have revealed that approximately 30% of CCCAs are associated with peptidyl arginine deiminase 3 misfolding mutations. Patients with CCCA usually have a poor prognosis with progressive and permanent hair loss. To further characterize CCCA, we evaluated the inflammatory milieu, PDL1, and caspase 3 expression. The data support the idea of CCCA being a CD4-predominant T-cell process. The loss of PDL1 and increase in caspase 3 expression raises the possibility of involvement of the PD1/PDL1 pathway in CCCA.

Immune-mediated alopecias and their mechanobiological aspects

Alopecia is a non-specific term for hair loss clinically diagnosed by the hair loss pattern and histological analysis of patient scalp biopsies. The immune-mediated alopecia subtypes, including alopecia areata, lichen planopilaris, frontal fibrosing alopecia, and central centrifugal cicatricial alopecia, are common, significant forms of alopecia subtypes. For example, alopecia areata is the most common autoimmune disease with a lifetime incidence of approximately 2% of the world's population. In this perspective, we discuss major results from studies of immune-mediated alopecia subtypes. These studies suggest the key event in disease onset as the collapse in immune privilege, which alters the hair follicle microenvironment, e.g., upregulation of major histocompatibility complex molecules and increase of cytokine production, and results in immune cell infiltration, inflammatory responses, and damage of hair follicles. We note that previous studies have established that the hair follicle has a complex mechanical microenvironment, which may regulate the function of not only tissue cells but also immune cell infiltrates. This suggests a potential for mechanobiology to contribute to alopecia research by adding new methods, new approaches, and new ways of thinking, which is missing in the existing literature. To fill this a gap in the alopecia research space, we develop a mechanobiological hypothesis that alterations in the hair follicle microenvironment, specifically in the mechanically responsive tissues and cells, partially due to loss of immune privilege, may be contributors to disease pathology. We further focus our discussion on the potential for applying mechanoimmunology to the study of T cell infiltrates in the hair follicle, as they are considered primary contributors to alopecia pathology. To establish the connection between the mechanoimmunological hypothesis and immune-mediated alopecia subtypes, we discuss what is known about the role of T cells in immune-mediated alopecia subtypes, using the most extensively studied AA as our model.

Treatment-Refractory Central Centrifugal Cicatricial Alopecia Responsive to a Novel Botanical Treatment

Purpose

Central centrifugal cicatricial alopecia (CCCA) is the most common cause of scarring alopecia in women of African descent. However, current treatments for CCCA, such as immunosuppressants and immunomodulatory pharmaceutical agents, have suboptimal efficacy and undesirable side effects. This case series reports the therapeutic effect of a new botanical formulation (Dr. UGro Gashee) in four patients with histologically supported diagnoses of CCCA. The formulations contain at least three phytoactive ingredients that affect multiple targets in the cascade of pathophysiologic events contributing to CCCA. Possible mechanisms of action include anti-inflammatory effects, inhibiting proinflammatory cytokines, and the net antifibrotic effect of inhibiting transforming growth factor-beta while upregulating AMP-activated protein kinase and peroxisome proliferator-associated receptor-gamma activity.

Patients and Methods

Four African American women with treatment-refractory CCCA were treated with a new topical botanical formula (cosmeceutical) alone or in combination with its oral formulation (nutraceutical) for 8 weeks to 1 year. The cosmeceutical and nutraceutical treatments contain similar phytoactive ingredient profiles. Treatment outcomes were collected using documented patient reports and images and by direct observation.

Results

In all patients, scalp pruritus cessation occurred within 2 weeks of treatment, and significant hair regrowth was observed within 2 months. All patients reported a high satisfaction level without adverse effects.

Conclusion

Patients with treatment-refractory CCCA responded to the novel botanical treatment reported in this study. Further evaluations in a controlled trial with more patients are warranted.

Scalp and serum profiling of frontal fibrosing alopecia reveals scalp immune and fibrosis dysregulation with no systemic involvement

BACKGROUND

Frontal fibrosing alopecia (FFA) is a progressive, scarring alopecia of the frontotemporal scalp that poses a substantial burden on quality of life. Large-scale global profiling of FFA is lacking, preventing the development of effective therapeutics.

OBJECTIVE

To characterize FFA compared to normal and alopecia areata using broad molecular profiling and to identify biomarkers linked to disease severity.

METHODS

This cross-sectional study assessed 33,118 genes in scalp using RNA sequencing and 350 proteins in serum using OLINK high-throughput proteomics. Disease biomarkers were also correlated with clinical severity and a fibrosis gene set.

RESULTS

Genes differentially expressed in lesional FFA included markers related to Th1 (IFNγ/CXCL9/CXCL10), T-cell activation (CD2/CD3/CCL19/ICOS), fibrosis (CXCR3/FGF14/FGF22/VIM/FN1), T-regulatory (FOXP3/TGFB1/TGFB3), and Janus kinase/JAK (JAK3/STAT1/STAT4) (Fold changes [FCH]>1.5, FDR<.05 for all). Only one protein, ADM, was differentially expressed in FFA serum compared to normal (FCH>1.3, FDR<.05). Significant correlations were found between scalp biomarkers (IL-36RN/IL-25) and FFA severity, as well as between JAK/STAT and fibrosis gene-sets (r>.6; P <.05).

LIMITATIONS

This study was limited by a small sample size and predominantly female FFA patients.

CONCLUSION

Our data characterize FFA as an inflammatory condition limited to scalp, involving Th1/JAK skewing, with associated fibrosis and elevated T-regulatory markers, suggesting the potential for disease reversibility with JAK/STAT inhibition.

A Cell Membrane-Level Approach to Cicatricial Alopecia Management: Is Caveolin-1 a Viable Therapeutic Target in Frontal Fibrosing Alopecia?

Irreversible destruction of the hair follicle (HF) in primary cicatricial alopecia and its most common variant, frontal fibrosing alopecia (FFA), results from apoptosis and pathological epithelial-mesenchymal transition (EMT) of epithelial HF stem cells (eHFSCs), in conjunction with the collapse of bulge immune privilege (IP) and interferon-gamma-mediated chronic inflammation. The scaffolding protein caveolin-1 (Cav1) is a key component of specialized cell membrane microdomains (caveolae) that regulates multiple signaling events, and even though Cav1 is most prominently expressed in the bulge area of human scalp HFs, it has not been investigated in any cicatricial alopecia context. Interestingly, in mice, Cav1 is involved in the regulation of (1) key HF IP guardians (TGF-β and α-MSH signaling), (2) IP collapse inducers/markers (IFNγ, substance P and MICA), and (3) EMT. Therefore, we hypothesize that Cav1 may be an unrecognized, important player in the pathobiology of cicatricial alopecias, and particularly, in FFA, which is currently considered as the most common type of primary lymphocytic scarring alopecia in the world. We envision that localized therapeutic inhibition of Cav1 in management of FFA (by cholesterol depleting agents, i.e., cyclodextrins/statins), could inhibit and potentially reverse bulge IP collapse and pathological EMT. Moreover, manipulation of HF Cav1 expression/localization would not only be relevant for management of cicatricial alopecia, but FFA could also serve as a model disease for elucidating the role of Cav1 in other stem cell- and/or IP collapse-related pathologies.

Mitochondrial Sirtuins in Skin and Skin Cancers

Mammalian sirtuins (SIRTs 1-7) are a family of NAD+-dependent deacetylases with distinct subcellular localization and biological functions that regulate various important cellular processes. Among these, SIRTs -3, -4 and -5 are located in the mitochondria and have been implicated in caloric restriction, oxidative stress, aging and various human diseases. Emerging evidence has found dysregulation of mitochondrial sirtuins in multiple dermatological conditions, including responses to ultraviolet radiation (UVR), suggesting their importance in maintaining skin health. In this review, we discuss the roles and implications of mitochondrial sirtuins in cutaneous cellular processes, and their emerging potential as a target for the management of skin diseases, including skin cancer. Among mitochondrial sirtuins, SIRT3 is the most studied and linked to multiple skin conditions and diseases (keratinocyte differentiation, wound healing, chronological aging, UVR and ozone response, systemic sclerosis, melanoma, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)). SIRT4 has been connected to keratinocyte differentiation, chronological aging, UVR response, alopecia, BCC and SCC. Further, SIRT5 has been associated with keratinocyte differentiation, melanoma, BCC and SCC. Overall, while there is compelling evidence for the involvement of mitochondrial sirtuins in skin, additional detailed studies are needed to understand their exact roles in skin and skin cancers.

Deimination and Peptidylarginine Deiminases in Skin Physiology and Diseases

Deimination, also known as citrullination, corresponds to the conversion of the amino acid arginine, within a peptide sequence, into the non-standard amino acid citrulline. This post-translational modification is catalyzed by a family of calcium-dependent enzymes called peptidylarginine deiminases (PADs). Deimination is implicated in a growing number of physiological processes (innate and adaptive immunity, gene regulation, embryonic development, etc.) and concerns several human diseases (rheumatoid arthritis, neurodegenerative diseases, female infertility, cancer, etc.). Here, we update the involvement of PADs in both the homeostasis of skin and skin diseases. We particularly focus on keratinocyte differentiation and the epidermal barrier function, and on hair follicles. Indeed, alteration of PAD activity in the hair shaft is responsible for two hair disorders, the uncombable hair syndrome and a particular form of inflammatory scarring alopecia, mainly affecting women of African ancestry.