Exosomes Secreted from Adipose-Derived Stem Cells Are a Potential Treatment Agent for Immune-Mediated Alopecia.

BACKGROUND: Alopecia has become an exceedingly prevalent dermatological disorder. Etiologically, infection (bacterial and fungal infection), inflammation, and immune dysregulation are the main causes of immune-mediated hair loss. Treating hair loss has remained challenging as the available therapies are limited. Exosomes from adipose-derived stem cells (ADSC-Exos) have been used for treating neurodegenerative diseases and autoimmune diseases and in wound-healing treatments. However, the function and mechanism of ADSC-Exos in alopecia treatment remain unclear. This study is aimed at investigating the effects of ADSC-Exos on hair growth in vitro and in vivo for potentially treating immune-mediated alopecia and further exploring the underlying mechanism. METHODS: Cell proliferation, migration, and apoptosis of dermal papilla cells (DPCs) that were treated with ADSC-Exos were detected using the cell counting kit-8 (CCK-8) assay, scratch wound-healing assay, and flow cytometry assay, respectively. A C57BL/6 hair-depilated mouse model was established in vivo; then, ADSC-Exos were subcutaneously injected alone or in combined with minoxidil. The effects of ADSC-Exos on hair growth, pathological changes, and the related mechanism were investigated by HE staining, quantitative real-time PCR (qRT-PCR), western blotting, and RNA sequencing (RNA-seq). RESULTS: ADSC-Exos significantly promoted DPC proliferation and migration while also reducing apoptosis. In addition, compared with the control group, ADSC-Exos-treated mice had better hair growth, more hair follicles (HFs) and thicker dermis. RNA-seq revealed that the miR-22 and TNF-α signaling pathways were markedly downregulated in DPCs after ADSC-Exos treatment. In addition, according to qRT-PCR and western blotting results, the Wnt/ß-catenin signaling pathway was activated in the skin of ADSC-Exos-treated mice. CONCLUSION: ADSC-Exos therapy positively affected the promotion of hair regrowth by regulating miR-22, the Wnt/ß-catenin signaling pathway, and the TNF-α signaling pathway, implying that ADSC-Exos could be a promising cell-free therapeutic strategy for immune-mediated alopecia.

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.

CCL13 is upregulated in alopecia areata lesions and is correlated with disease severity.

Alopecia areata (AA) is a multi-factors disease characterized by non-scarring hair loss. AA could be classified into three main clinical phenotypes including patchy type AA (AAP), alopecia totalis (AT) and alopecia universalis (AU) based on the severity and areas of hair loss. Recent studies suggested immunological factor was critical in AA, but the precise aetiology and pathogenesis of AA still need exploration. In the work, we screened two gene expression profiles (GSE45512 and GSE68801) from Gene Expression Omnibus (GEO). Based on the two data sets, 10 upregulated genes and 107 downregulated genes in AA skin biopsies were identified. CCL13, as one of the remarkably upregulated genes, was found to have potential biological functions in aberrant immune response of AA according to the GO and KEGG analyses. The PPI network showed CCL13 was associated with multiple immune-related genes. The expression of CCL13 was increased depending on the severity of disease in AA patients. Cytotoxic lymphocytes, T cells and myeloid dendritic cells accumulated remarkably in scalp tissue depending on the severity of AA, and CCL13 was significantly correlated to cytotoxic lymphocytes, T cells and myeloid dendritic cells in AA patients. Our RT-PCR and ELISA results found CCL13 was upregulated in skin biopsy and serum of AA patients, and the immunohistochemistry (IHC) detection showed CCL13 was expressed by both the hair follicle epithelium and infiltrating immune cells. In conclusion, the upregulated of CCL13 and subsequent immune cell infiltration was related to AA, which could be a promising target for diagnosis and therapy in AA patients.

Immune cell regulation of the hair cycle.

The ability to manipulate the mammalian hair cycle will lead to novel therapies and strategies to combat all forms of alopecia. Thus, in addition to the epithelial-mesenchymal interactions in the hair follicle, niche and microenvironmental signals that accompany the phases of growth, regression and rest need to be scrutinized. Immune cells are well described in skin homeostasis and wound healing and have recently been shown to play an important role in the mammalian hair cycle. In this review, we will summarize our current knowledge of the role of immune cells in hair cycle control and discuss their relevance to human hair cycling disorders. Increased attention to this aspect of the hair cycle will provide new avenues to manipulate hair regeneration in humans and provide better insight into developing better ex vivo models of hair growth.

Clinicopathologic and immunophenotypic characterization of lichen planopilaris and central centrifugal cicatricial alopecia: A comparative study of 51 cases.

BACKGROUND: The purpose of the study was to compare the histopathologic and immunophenotypic features of central centrifugal cicatricial alopecia (CCCA) and lichen planopilaris (LPP) to better characterize and differentiate these two clinical entities. CCCA remains an ill-defined and still-unsettled histologic entity and many hair loss experts regard CCCA to be histologically indistinguishable from LPP. Given the overlapping histologic features of these two lymphocyte-predominant cicatricial alopecias, and the lack of consensus regarding the significance of proposed distinctions, dermatopathologists face difficulty in providing clinicians and patients certainty with a definitive diagnosis of CCCA vs LPP. METHODS: We performed a retrospective review of 51 scalp biopsies of patients with either the clinical diagnosis of CCCA (27 cases) or LPP (24 cases). Clinical information, histologic features of hematoxylin-eosin-stained sections, and a panel of immunohistochemical markers were evaluated on scalp biopsies. Tested parameters were quantified, and statistical analysis was performed. RESULTS: Our study found no differences on either histologic assessment or immunophenotypic characterization between cases of classic LPP and CCCA. CONCLUSION: The conclusion of this study is that the inflammatory infiltrates in CCCA and LPP are not only histologically similar but also immunophenotypically indistinguishable.

Overexpression of MYB in the Skin Induces Alopecia and Epidermal Hyperplasia.

Skin homeostasis is controlled by a complex interplay between tightly regulated transcription factors and signaling pathways. MYB is a transcription factor expressed in hair follicle progenitor cells and found overexpressed in adnexal skin tumors. However, the biological consequences of deregulated MYB expression in the skin remain poorly understood. To address this, we generated transgenic mice that overexpress MYB in epidermal and follicular keratinocytes. These mice exhibited a normal hair coat after birth but gradually developed alopecia, accompanied by altered follicular differentiation, disrupted hair cycle, and a marked depletion of hair follicle stem cells. Additionally, transgenic mice developed massive epidermal hyperplasia and hyperkeratosis. Global expression profiling not only confirmed that the skin of these mice exhibited transcriptomic features of alopecia and epidermal differentiation, but also revealed features of psoriasis and the inflammatory response. The latter was further confirmed by the increased T-cell infiltration found in the skin of transgenic mice. Overall, these results suggest that tight regulation of MYB expression in the skin is critical to maintain skin homeostasis.

Downregulation of integrin-αvß6 on keratinocytes in the scar of lichen planopilaris and folliculitis decalvans: Relevance for the disappearance of epidermal Langerhans cells.

Primary cicatricial alopecia (PCA) is a group of poorly understood mechanisms in which the destruction of hair follicles leads to permanent hair loss. Lichen planopilaris (LPP) is a type of lymphocytic PCA and it has been known for epidermal Langerhans cells (LC) to disappear in the scar of LPP. We also found that epidermal LC also disappeared in the scar of folliculitis decalvans (FD), a type of neutrophilic PCA. Of note was that epidermal LC did not disappear in the scar of discoid lupus erythematosus, another type of lymphocytic PCA, suggesting that LC disappearance in the scar was not always a common feature of PCA. We found that the expression of integrin (ITG)-αvß6 in scar epidermis was significantly diminished in LPP and FD, but not in other PCA and disorders accompanied with scar formation. We also found that exogenous interleukin-1ß and α-interferon downregulated ITG-αvß6 expression in normal human epidermal keratinocytes. These data suggest that downregulation of ITG-αvß6 may be one of the causes of LC disappearance in the scar of LPP and FD.

An update of the pathogenesis of frontal fibrosing alopecia: What does the current evidence tell us?

Frontal fibrosing alopecia (FFA) is a primary patterned cicatricial alopecia with a complicated pathogenesis yet to be fully understood. FFA appears to be increasing in incidence worldwide, especially in the last decade. In order to consider current treatment options, we reviewed current evidence for its pathogenesis comprising immune-mediated, genetic, hormonal and environmental factors. Th1-mediated inflammation with collapse of hair follicle immune privilege and bulge epithelial stem cell destruction, peroxisome proliferator-activated receptor gamma (PPAR-γ) depletion and epithelial-mesenchymal transition are key events leading to permanent hair follicle destruction in FFA. Although the vast majority of cases are sporadic, familial reports of FFA implicate genetic or epigenetic mechanisms in its pathogenesis. The frequent onset of FFA in post-menopausal women, similar patterning and co-existence with female pattern hair loss, together with a reportedly good response to 5α-reductase inhibitors suggest a role for sex steroid hormones. The reported increasing incidence invites speculation for, yet unproven, environmental triggers such as sun exposure and topical allergens. More robust research into this unique entity is required to help understand the complexity of the pathogenesis of FFA in order to find satisfactory therapeutic targets for this often distressing condition.

Lichen Planopilaris and Frontal Fibrosing Alopecia as Model Epithelial Stem Cell Diseases.

Inflammation-associated, irreversible damage to epithelial stem cells (eSCs) of the hair follicle in their immunologically privileged niche lies at the heart of scarring alopecia, which causes permanent difficult-to-treat hair loss. We propose that the two most common and closely related forms, lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA), provide excellent model diseases for studying the biology and pathology of adult human eSCs in an easily accessible human mini-organ. Emphasising the critical roles for interferon (IFN)-γ and peroxisome proliferator-activated receptor (PPAR)-γ-mediated signalling in immune privilege (IP) collapse and epithelial-mesenchymal transition (EMT) of these eSCs respectively, we argue that these pathways deserve therapeutic targeting in the future management of LPP/FFA and other eSC diseases associated with IP collapse and EMT.

Anti-SmD1 antibodies are associated with renal disorder, seizures, and pulmonary arterial hypertension in Chinese patients with active SLE.

Detection of autoantibodies in systemic lupus erythematosus (SLE) plays an important role in timely diagnosis and earlier treatment of SLE. In this study, we used a SmD1 polypeptide-based ELISA to determine anti-SmD1 antibody in 269 SLE, including100 naïve (had not been treated with steroids or immunosuppressants at study inception) SLE patients and 169 non-naive SLE patients; 233 controls with other rheumatic diseases (RDC) (70 RA, 40 AS, 73SSc, and 50 SS), and 110 healthy controls (HC) group. The positive rate of anti-SmD1 among all SLE patients was 60.97%, higher than that in the RDC group (13.30%, P = 0.000) or the HC group (9.09%, P = 0.000). The positive rate of anti-SmD1 in non-naive SLE patients was higher than that for anti-dsDNA antibodies (44.97%, P = 0.03). Positivity for anti-SmD1 only was found in 14.00% of naive SLE patients and 16.00% of non-naive SLE patients. In naive SLE patients, the serum concentration of anti-SmD1 was lower after treatment than before treatment (P = 0.039). Active SLE patients positive for anti-SmD1 were more likely to have malar rash, rash, nonscarring alopecia, PAH and hypocomplementemia. High positivity for anti-SmD1 only in patients with SLE indicated the importance and necessity of detection of anti-SmD1 in patients with SLE.

5-Bromo-2'-deoxyuridine induced effluvium via p53-mediated CD326-positive keratinocyte apoptosis in C57BL/6 mice.

Anagen effluvium develops because of disturbances in the hair follicle cycle, leading to acute and severe hair loss in humans. The objective of this study was to establish a mouse model of anagen effluvium by 5-bromo-2'-deoxyuridine (BrdU) treatment, and evaluate the pathological changes and underlying mechanisms. We treated 9-10-day-old pups and 3-7-week-old C57BL/6 mice with BrdU. After successfully inducing hair loss in the neonatal pups, microscopic, immunohistochemical and flow cytometry analyses were conducted. BrdU induced early onset alopecia in neonates and caused epidermal thickening and hair shaft breakage. BrdU appeared to incorporate the CD326-positive keratinocyte layer and induced p53-related apoptosis. Keratinocyte apoptosis caused immune cell infiltration in the dermal region; M2 macrophages and neutrophils were dominant. The BrdU-induced hair loss was dose-dependent, and alopecia was visible at a dose range of 25-200 µg/g bodyweight. The BrdU-induced anagen effluvium mouse model is novel and easily established by administrating four simple BrdU injections to pups; these mice showed synchronized onset of alopecia symptoms with little individual variation. Moreover, this model showed an alopecia phenotype similar to that of human anagen effluvium with acute, severe and widespread hair loss.

A Novel Xenogeneic Graft-Versus-Host Disease Model for Investigating the Pathological Role of Human CD4+ or CD8+ T Cells Using Immunodeficient NOG Mice.

Graft-versus-host disease (GVHD) is a major complication of allogenic bone marrow transplantation and involves the infiltration of donor CD4+ and/or CD8+ T cells into various organs of the recipient. The pathological role of human CD4+ and CD8+ T cells in GVHD remains controversial. In this study, we established two novel xenogeneic (xeno)-GVHD models. Human CD4+ or CD8+ T cells were purified from peripheral blood and were transplanted into immunodeficient NOD/Shi-scid IL2rgnull (NOG) mice. Human CD8+ T cells did not induce major GVHD symptoms in conventional NOG mice. However, CD8+ T cells immediately proliferated and induced severe GVHD when transferred into NOG mice together with at least 0.5 × 106 CD4+ T cells or into NOG human interleukin (IL)-2 transgenic mice. Human CD4+ T cell-transplanted NOG mice developed skin inflammations including alopecia, epidermal hyperplasia, and neutrophilia. Pathogenic T helper (Th)17 cells accumulated in the skin of CD4+ T cell-transplanted NOG mice. Further, an anti-human IL-17 antibody (secukinumab) significantly suppressed these skin pathologies. These results indicate that pathogenic human Th17 cells induce cutaneous GVHD via IL-17-dependent pathways. This study provides fundamental insights into the pathogenesis of xeno-GVHD, and these humanized mouse models may be useful as preclinical tools for the prevention of GVHD.

Frontal fibrosing alopecia in association with Sjögren's syndrome: more than a simple coincidence

Abstract Frontal fibrosing alopecia is a distinctive form of scarring alopecia considered to be a clinical variant of lichen planopilaris. It predominantly occurs in postmenopausal women and has a slowly progressive course. It was first described by Kossard in 1994. Since then the number of reported cases has increased significantly. Coexistence of frontal fibrosing alopecia and autoimmune disorders - such as discoid erythematosus lupus and Sjögren's syndrome - may suggest a common pathogenic background among the diseases.