Sterol Intermediates of Cholesterol Biosynthesis Inhibit Hair Growth and Trigger an Innate Immune Response in Cicatricial Alopecia

Primary cicatricial alopecia (PCA) is a group of inflammatory hair disorders that cause scarring and permanent hair loss. Previous studies have implicated PPARγ, a transcription factor that integrates lipogenic and inflammatory signals, in the pathogenesis of PCA. However, it is unknown what triggers the inflammatory response in these disorders, whether the inflammation is a primary or secondary event in disease pathogenesis, and whether the inflammatory reaction reflects an autoimmune process. In this paper, we show that the cholesterol biosynthetic pathway is impaired in the skin and hair follicles of PCA patients. Treatment of hair follicle cells with BM15766, a cholesterol biosynthesis inhibitor, or 7-dehydrocholesterol (7-DHC), a sterol precursor, stimulates the expression of pro-inflammatory chemokine genes. Painting of mouse skin with 7-DHC or BM15766 inhibits hair growth, causes follicular plugging and induces the infiltration of inflammatory cells into the interfollicular dermis. Our results demonstrate that cholesterologenic changes within hair follicle cells trigger an innate immune response that is associated with the induction of toll-like receptor (TLR) and interferon (IFN) gene expression, and the recruitment of macrophages that surround the hair follicles and initiate their destruction. These findings reveal a previously unsuspected role for cholesterol precursors in PCA pathogenesis and identify a novel link between sterols and inflammation that may prove transformative in the diagnosis and treatment of these disorders

Clinical and Pathologic Correlations in Genetically Distinct Forms of Atrichia

14 páginas, 2 figuras.BACKGROUND: The genetic basis of 2 distinct forms of atrichia with papules has recently been defined at the molecular level. In atrichia with papular lesions (APL; Online Mendelian Inheritance in Man [OMIM] 209500), mutations in the hairless gene on chromosome 8p21 have recently been identified. Atrichia with papules also occurs in the clinical setting of vitamin D-dependent rickets type IIA (VDDR IIA; OMIM 277440), resulting from mutations in the vitamin D receptor gene on chromosome 12q12-q14. Despite the distinct genetic basis for both forms of atrichia, the clinical findings are strikingly similar and exhibit classic pathognomonic features unique to this phenotype. We sought to document the clinical and molecular features of APL and VDDR IIA. OBSERVATIONS: Molecular analysis of the hairless and vitamin D receptor genes was performed on genomic DNA from probands and family members from 3 families with APL and 2 with VDDR IIA. We present a clinical and histologic comparison of atrichia in patients with APL and VDDR IIA and highlight the genetically heterogeneous basis of atrichia by identification of pathogenetic mutations. CONCLUSIONS: Increased awareness of these diseases will allow early diagnosis and potential therapeutic intervention for the rickets in VDDR IIA and avoidance of treatment of the atrichia in both APL and VDDR IIA. Their phenotype similarities suggest the possibility of a functional relationship between HR and VDR.This work was supported by National Institutes of Health grants R01-AR 47338 (Dr Christiano) R03-AR 047403-03, and K01-AR 002204-03 (Dr Panteleyev), and by a grant from the Joint Research Fund of the Hebrew University and Hadassah Medical Center (Dr Zlotogorski).Peer reviewe

Protein profiling of forehead epidermal corneocytes distinguishes frontal fibrosing from androgenetic alopecia.

Protein profiling offers an effective approach to characterizing how far epidermis departs from normal in disease states. The present pilot investigation tested the hypothesis that protein expression in epidermal corneocytes is perturbed in the forehead of subjects exhibiting frontal fibrosing alopecia. To this end, samples were collected by tape stripping from subjects diagnosed with this condition and compared to those from asymptomatic control subjects and from those exhibiting androgenetic alopecia. Unlike the latter, which exhibited only 3 proteins significantly different from controls in expression level, forehead samples from frontal fibrosing alopecia subjects displayed 72 proteins significantly different from controls, nearly two-thirds having lower expression. The results demonstrate frontal fibrosing alopecia exhibits altered corneocyte protein expression in epidermis beyond the scalp, indicative of a systemic condition. They also provide a basis for quantitative measures of departure from normal by assaying forehead epidermis, useful in monitoring response to treatment while avoiding invasive biopsy

Protein profiling of forehead epidermal corneocytes distinguishes frontal fibrosing from androgenetic alopecia.

Protein profiling offers an effective approach to characterizing how far epidermis departs from normal in disease states. The present pilot investigation tested the hypothesis that protein expression in epidermal corneocytes is perturbed in the forehead of subjects exhibiting frontal fibrosing alopecia. To this end, samples were collected by tape stripping from subjects diagnosed with this condition and compared to those from asymptomatic control subjects and from those exhibiting androgenetic alopecia. Unlike the latter, which exhibited only 3 proteins significantly different from controls in expression level, forehead samples from frontal fibrosing alopecia subjects displayed 72 proteins significantly different from controls, nearly two-thirds having lower expression. The results demonstrate frontal fibrosing alopecia exhibits altered corneocyte protein expression in epidermis beyond the scalp, indicative of a systemic condition. They also provide a basis for quantitative measures of departure from normal by assaying forehead epidermis, useful in monitoring response to treatment while avoiding invasive biopsy