Cholesterol homeostasis: Links to hair follicle biology and hair disorders.

Lipids and lipid metabolism are critical factors in hair follicle (HF) biology, and cholesterol has long been suspected of influencing hair growth. Altered cholesterol homeostasis is involved in the pathogenesis of primary cicatricial alopecia, mutations in a cholesterol transporter are associated with congenital hypertrichosis, and dyslipidaemia has been linked to androgenic alopecia. The underlying molecular mechanisms by which cholesterol influences pathways involved in proliferation and differentiation within HF cell populations remain largely unknown. As such, expanding our knowledge of the role for cholesterol in regulating these processes is likely to provide new leads in the development of treatments for disorders of hair growth and cycling. This review describes the current state of knowledge with respect to cholesterol homeostasis in the HF along with known and putative links to hair pathologies.

A case of H syndrome showing immunophenotye similarities to Rosai-Dorfman disease.

H syndrome (OMIM 612391) is a recently described autosomal recessive genodermatosis characterized by indurated, hyperpigmented, and hypertrichotic skin and systemic manifestations including hepatosplenomegaly, cardiac anomalies, hearing loss, hypogonadism, low height, hypertriglyceridemia, hallux valgus, and flexion contractures. H syndrome results from mutations in the SLC29A3 gene, which encodes the human equilibrative nucleoside transporter hENT3. The cutaneous histopathology is characterized by a striking mononuclear cell infiltrate in the dermis consisting of CD68+ monocyte-derived cells and CD34+ and factor XIIIa+ dendrocytes. We describe a case of H syndrome in which the infiltrating mononuclear cells were CD68+, CD163+, S-100+, and CD1a-, thus simulating the immunophenotype observed in Rosai-Dorfman disease (RDD). The immunostaining for CD21, fascin, and CD34 were negative, and there were also many factor XIIIa+ dendrocytes interspersed within the dense mononuclear cell infiltrate. Recent findings of biallelic mutations in SLC29A3 in 2 families reported to have familial RDD and in a kindred with Faisalabad histiocytosis (OMIM 602782), which is an autosomal inherited form of histiocytosis with similarities to RDD, may explain the RDD-like immunophenotype in our H syndrome case.

Desmoglein 4 in hair follicle differentiation and epidermal adhesion: evidence from inherited hypotrichosis and acquired pemphigus vulgaris.

Cell adhesion and communication are interdependent aspects of cell behavior that are critical for morphogenesis and tissue architecture. In the skin, epidermal adhesion is mediated in part by specialized cell-cell junctions known as desmosomes, which are characterized by the presence of desmosomal cadherins, known as desmogleins and desmocollins. We identified a cadherin family member, desmoglein 4, which is expressed in the suprabasal epidermis and hair follicle. The essential role of desmoglein 4 in skin was established by identifying mutations in families with inherited hypotrichosis, as well as in the lanceolate hair mouse. We also show that DSG4 is an autoantigen in pemphigus vulgaris. Characterization of the phenotype of naturally occurring mutant mice revealed disruption of desmosomal adhesion and perturbations in keratinocyte behavior. We provide evidence that desmoglein 4 is a key mediator of keratinocyte cell adhesion in the hair follicle, where it coordinates the transition from proliferation to differentiation.

[Marked endocrine abnormalities in polyneuritis with skin hyperpigmentation, hypertrichosis, edema and increased lambda type immunoglobulin A: a case report].

A syndrome which is known as plasma cell dyscrasia with polyneuropathy and various endocrine manifestations or plasma cell dyscrasia with polyneuropathy, organomegaly, endocrinopathy, abnormal M protein and skin changes is very interesting because this syndrome has miscellaneous manifestations such as skin hyperpigmentation, hypertrichosis, polyneuropathy, M protein abnormality, plasma cell dyscrasia and endocrine disturbances. Miscellaneous endocrine abnormalities which have not been described so far are reported here. A 47 year old female was admitted with the chief complaints of edema and gait disturbance. Past and family histories were noncontributory. In April 1981, edema appeared in her face and legs. In June she noticed paresthesia in her legs. Edema increased gradually and she had difficulty walking. Her skin became pigmented and hairy. In October she was admitted because of polyneuropathy with increased cerebrospinal fluid protein without pleocytosis. Prednisolone was started. Walking improved slightly, but edema and paresthesia remained unchanged. Prednisolone was stopped at the end of the following March. In May 1982, she was admitted for further evaluation of edema and polyneuropathy. The patient was alert and cooperative. On standing the skin of her legs became cyanotic. There was hypertrichosis on the arms and legs. Her fingers were clubbed. A moderate swelling of the cervical lymph nodes was noted. There was mild hepatomegaly without splenomegaly. All tendon reflexes were lost. Plantar response was flexor. Muscular strength diminished mildly. She complained of paresthesia on the soles. Superficial sensation was normal. Vibratory sense decreased mildly. Cerebellar function and cranial nerves were normal. There was no sphincter disturbance. The examination of urine, stool and peripheral blood was normal.(ABSTRACT TRUNCATED AT 250 WORDS)