Comparative Analysis of Immunopathological Features of Lichen Planopilaris and Female Patients with Frontal Fibrosing Alopecia

Frontiers in Lichen Planopilaris and Frontal Fibrosing Alopecia Research: Pathobiology Progress and Translational Horizons

Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) are primary, lymphocytic cicatricial hair loss disorders. These model epithelial stem cell (SC) diseases are thought to result from a CD8⁺ T-cell‒dominated immune attack on the hair follicle (HF) SC niche (bulge) after the latter has lost its immune privilege (IP) for as yet unknown reasons. This induces both apoptosis and pathological epithelial‒mesenchymal transition in epithelial SCs, thus depletes the bulge, causes fibrosis, and ultimately abrogates the HFs' capacity to regenerate. In this paper, we synthesize recent progress in LPP and FFA pathobiology research, integrate our limited current understanding of the roles that genetic, hormonal, environmental, and other factors may play, and define major open questions. We propose that LPP and FFA share a common initial pathobiology, which then bifurcates into two distinct clinical phenotypes, with macrophages possibly playing a key role in phenotype determination. As particularly promising translational research avenues toward direly needed progress in the management of these disfiguring, deeply distressful cicatricial alopecia variants, we advocate to focus on the development of bulge IP and epithelial SC protectants such as, for example, topically effective, HF‒penetrating and immunoinhibitory preparations that contain tacrolimus, peroxisome proliferator-activated receptor-γ, and/or CB1 agonists.

Lichen planopilaris and frontal fibrosing alopecia: review and update of diagnostic and therapeutic features

Lichen planopilaris and frontal fibrosing alopecia are primary scarring alopecias where diagnosis can be suggested by clinical and trichoscopy features, especially in the early stages, but scalp biopsy is the standard exam for definitive diagnosis. Frontal fibrosing alopecia is considered a variant of lichen planopilaris, as the histopathological findings are similar, with a perifollicular lymphohistiocytic infiltrate, sometimes with a lichenoid pattern. A thorough clinical examination, trichoscopy and photographic documentation are essential to assess the evolution and therapeutic response. To date, there are no validated treatments or guidelines for these diseases, but there are recommendations that vary with the individual characteristics of each patient. This article presents a comprehensive review of the literature, including an update on topics related to the diagnosis, follow-up, histopathological aspects and available treatments for lichen planopilaris and frontal fibrosing alopecia, highlighting their similarities, differences and peculiarities.

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.

Histopathological and immunohistochemical features of facial papules in frontal fibrosing alopecia

BACKGROUND

Facial papules (FPs) are considered to be created by the inflammatory process, which involves facial vellus hairs, in frontal fibrosing alopecia.

AIM

To demonstrate the histopathological features of FPs and the composition of the inflammatory infiltrate.

METHODS

In total, 18 patients with FPs were enrolled in the study after histopathological confirmation of lichen planopilaris. Histopathological evaluation of the specimens was performed by two dermatopathologists. The samples were immunostained with CD4, CD8 and CD123 monoclonal antibodies, and the percentage and proportion of cells stained with these markers were investigated.

RESULTS

A follicular lichenoid reaction and perifollicular fibrosis were present in all cases. Vellus hairs were detected in 83.3% of biopsy specimens (15 cases), all of which were involved by the inflammation. The majority of the follicles (72%) revealed follicular plugs. Reduction and destruction of elastic fibres were visible in the perifollicular (adventitial) and the papillary dermis (100% and 78% of specimens, respectively). Prominent sebaceous glands and dilated ducts were detected in 78% and 72% of samples, respectively. CD4-positive T cells formed 67.72% and CD8-positive T cells 32.28% of the infiltrate, and the mean CD4/CD8 ratio was 2.48. In 13 (72.2%) biopsy specimens < 10% of the infiltrate was positive for CD123 marker.

CONCLUSIONS

Perifollicular inflammation, fibrosis and elastic-fibre destruction were constant histopathological features of FPs; furthermore, prominent sebaceous glands were present in the majority of samples. We also observed a CD4-positive predominance in the infiltrate.

Dysbiosis and Enhanced Beta-Defensin Production in Hair Follicles of Patients with Lichen Planopilaris and Frontal Fibrosing Alopecia

Despite their distinct clinical manifestation, frontal fibrosing alopecia (FFA) and lichen planopilaris (LPP) display similar histopathologic features. Aberrant innate immune responses to endogenous or exogenous triggers have been discussed as factors that could drive inflammatory cascades and the collapse of the stem cell niche. In this exploratory study, we investigate the bacterial composition of scalp skin and plucked hair follicles (HF) of patients with FFA, LPP and alopecia areata circumscripta (AAc), as well as healthy individuals, in relation to cellular infiltrates and the expression of defense mediators. The most abundant genus in lesional and non-lesional HFs of LPP and FFA patients was Staphylococcus, while Lawsonella dominated in healthy individuals and in AAc patients. We observed statistically significant differences in the ratio of Firmicutes to Actinobacteria between healthy scalp, lesional, and non-lesional sites of FFA and LPP patients. This marked dysbiosis in FFA and LPP in compartments close to the bulge was associated with increased HβD1 and HβD2 expression along the HFs from lesional sites, while IL-17A was increased in lesional HF from AAc patients. The data encourage further studies on how exogenous factors and molecular interactions across the HF epithelium could contribute to disease onset and propagation.

Frontal fibrosing alopecia

Frontal fibrosing alopecia (FFA) is a patterned primary cicatricial alopecia that was first described in 1994. Once rare, the incidence of FFA has increased dramatically, representing the current most common cause of cicatricial alopecia worldwide. FFA typically begins in postmenopausal women with symmetrical, progressive recession of the frontotemporal hairline together with bilateral loss of the eyebrows. FFA has a distinctive clinical phenotype, which remains a challenge. The histology is identical to lichen planopilaris (LPP), but only a small number of patients have coincidental LPP, usually of the scalp. The vast majority of patients have no evidence of lichen planus elsewhere, and the symmetry and patterned nature of the hair loss are unusual for LPP. Familial cases of FFA are reported, and gene associations have been identified in population studies; however, the pathophysiology remains controversial. Without treatment, FFA is slowly progressive, and although many treatments have been prescribed, the response is often disappointing. We review the pathogenesis, epidemiology, clinical features, histology, and treatment of FFA.

Frontal fibrosing alopecia shows robust T helper 1 and Janus kinase 3 skewing

BACKGROUND

Frontal fibrosing alopecia (FFA) is a scarring alopecia with unclear pathogenesis and a progressive course. The disease has a major impact on patients' quality of life and there is a lack of effective treatment to halt disease progression.

METHODS

We profiled lesional and nonlesional scalp biopsies collected in 2017 from patients with FFA (n = 12) compared with scalp biopsies from patients with alopecia areata (AA) (n = 8) and controls (n = 8) to evaluate gene and protein expression, including the primary outcome (CXCL9). We determined significant differences between biomarkers using a two-sided Student's t-test adjusting P-values by false discovery rate.

RESULTS

Significant increases were seen in CD8+ cytotoxic T cells, CD11c+ dendritic cells, CD103+ and CD69+ tissue-resident memory T cells in FFA and AA vs. control scalp (P < 0·05), with corresponding significantly upregulated granzyme B mRNA, particularly in FFA (P < 0·01). In AA, cellular infiltrates were primarily concentrated at the bulb, while in FFA these were mainly localized at the bulge. FFA demonstrated significant upregulation of T helper 1/intereferon (IFN) (IFN-γ, CXCL9/CXCL10), the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway (STAT1, JAK3) and fibrosis-related products (vimentin, fibronectin; P < 0·05), with no concomitant downregulation of hair keratins and the T-regulatory marker, forkhead box P3, which were decreased in AA. The stem cell markers CD200 and K15 demonstrated significantly reduced expression only in FFA (P < 0·05).

CONCLUSIONS

These data suggest that follicular damage and loss of stem cells in FFA may be mediated through immune attack in the bulge region, with secondary fibrosis and reduced but still detectable stem cells. JAK/STAT-targeting treatments may be able to prevent permanent follicular destruction and fibrosis in early disease stages.

Profiling the human hair follicle immune system in lichen planopilaris and frontal fibrosing alopecia: can macrophage polarization differentiate these two conditions microscopically?

BACKGROUND

Frontal fibrosing alopecia (FFA) is traditionally regarded as a variant of lichen planopilaris (LPP) based on histological features. Distinct clinical presentation, demographics and epidemiology suggest that differing pathogenic factors determine the final phenotype.

OBJECTIVES

To map the hair follicle immune system in LPP and FFA by systematically comparing key inflammatory markers in defined hair follicle compartments.

METHODS

Lesional scalp biopsies from LPP and FFA and healthy controls were stained with the following immunohistochemical markers: CD1a and CD209, CD4, CD8, CD56, CD68, CD123, CXCR3, forkhead box (FOX)P3, mast cell tryptase and cKit. Macrophage polarization was explored using CD206, CD163, CD86, receptor for advanced glycation end products (RAGE), interleukin (IL)-4 and IL-13 on paired lesional and nonlesional LPP and FFA samples.

RESULTS

Increased numbers of CD8⁺ , CXCR3⁺ and FOXP3⁺ T cells and CD68⁺ macrophages were identified in the distal hair follicle epithelium and perifollicular mesenchyme in both LPP and FFA compared with controls. In both LPP and FFA, total and degranulated mast cells and CD123⁺ plasmacytoid dendritic cells were increased in the perifollicular mesenchyme adjacent to the bulge and infundibulum, whereas numbers of CD1a⁺ and CD209⁺ dendritic cells were significantly reduced in the infundibulum connective tissue sheath. However, only with CD68 staining was a significant difference between LPP and FFA identified, with greater numbers of CD68⁺ cells in LPP samples. Furthermore, the identified macrophage polarization markers downregulated CD86 and upregulated CD163 and IL-4 expression in lesional LPP compared with FFA samples.

CONCLUSIONS

This comparative immunopathological analysis is the first to profile systematically the hair follicle immune system in LPP and FFA. Our analysis highlights a potential role of macrophages in disease pathobiology and suggests that macrophage polarization may differ between LPP and FFA, allowing microscopic differentiation. Linked Comment: Kinoshita-Ise. Br J Dermatol 2020; 183:419-420.

Single-center analysis of patients with frontal fibrosing alopecia: evidence for hypothyroidism and a good quality of life

Objective

Frontal fibrosing alopecia (FFA) is an underestimated scarring alopecia. This study aimed to examine epidemiological information, as well as predilection sites, associated diseases, and responses to therapy of patients with FFA. We also aimed to determine whether the extent or duration of disease correlated with the quality of life (QoL).

Methods

Twelve outpatients with FFA for > 2 years were analyzed. The Erlanger atopic score and the Functional Assessment of Non-life-threatening Conditions (FANLTC) for QoL-assessment were used as scoring systems.

Results

All patients were women with a mean age of 70.3 years. Most patients did not have any symptoms during their disease progression and no therapy that was used showed any significant effects. FFA was associated with hypothyroidism. There were no correlations between hairline regression, duration of disease, atopic disposition, and QoL. The overall QoL was good.

Conclusions

The present study shows that there is no correlation between the extent of FFA and QoL or atopic predisposition. There is a strong correlation between the incidence of thyroid disease and FFA.

Lichen planopilaris and frontal fibrosing alopecia cannot be differentiated by histopathology

BACKGROUND

Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) represent 2 entities that cause primary cicatricial alopecia. These entities are clinically different; nevertheless, the literature suggests that FFA represents a form of LPP. The main argument in support of this hypothesis is that previous studies comparing the histologic findings have not found obvious differences between these diseases.

METHODS

Our objective was to more critically compare and contrast 20 histologic findings of these diseases in a large number of patients in order to determine any significant histologic differences between LPP and FFA.

RESULTS

We found 3 parameters that were statistically different, namely the presence of terminal catagen-telogen hairs (50% FFA vs 23.5% LPP; P = .020); a severe perifollicular inflammatory infiltrate (29.4% LPP vs 4.6% FFA; P = .010) and a zone of concentric lamellar fibroplasia (85.3% LPP vs 63.6% FFA; P = .041).

CONCLUSIONS

Although a few histologic features differ between FFA and LPP, we believe that these differences are too subtle or non-specific to distinguish between them with confidence. Therefore, clinical correlation is essential to establish the diagnosis.

Ulcerating Lichen Planopilaris - Successful Treatment by Surgery

Lichen planus is a T-cell mediated autoimmune disorder affecting the skin and mucous membranes. Ulcerating lichen planus is uncommon mostly on oral and genital mucosa but not skin. Lichen planopilaris, however, is a subtype of lichen planus affection hair follicles and leading to permanent scarring alopecia. We report a case of lichen planopilaris of the scalp with multiple alopecic patches ulceration – a hitherto unreported clinical feature. The patient was treated surgically, and the defect could be closed by combined tissue advancement and extension.