Effects of NCSTN Mutation on Hair Follicle Components in Mice

BACKGROUND AND OBJECTIVES

Hidradenitis suppurativa (HS)/acne inversa is an intractable skin disease that is characterized by destructive lesions - primarily on the flexural areas. Although its etiology is unknown, genetics is considered to be a factor of its pathology - mutations in γ-secretase genes have been identified in certain familial HS patients, and follicular occlusion is widely accepted as the primary cause of HS. But, no relationship between these mutations and the components of hair follicles has been reported. Thus, we examined changes in these components in mice with a mutation in NCSTN (a γ-secretase gene).

METHODS

We generated C57BL/6 mice with an NCSTN mutation and examined their expression of hair cortex cytokeratin and trichohyalin by Western blot and immunohistochemistry, in addition to nicastrin, the product of NCSTN, and NICD compared with wild-type mice. The structure of hair follicles was analyzed by hematoxylin-eosin staining and transmission electron microscopy.

RESULTS

In mice with an NCSTN mutation, HS-like skin lesions appeared after age 6 months, the pathological manifestations of which were consistent with the features of human HS. The structure of hair follicles was abnormal in mice with an NCSTN mutation versus wild-type mice, and hair cortex cytokeratin, trichohyalin, nicastrin, and NICD were downregulated in these mice.

CONCLUSIONS

This NCSTN mutant mouse model could be an improved model to study early lesion development aspects of human HS pathogenesis and could perhaps be a better alternative for evaluating early-acting and preventive therapeutics for HS experimentally before clinical trials in HS patients. NCSTN mutations disrupt the development of hair follicles, leading to abnormal hair follicle structures, perhaps resulting in the onset of HS.

Pseudocyst of the scalp

Pseudocyst of the scalp is described in the Japanese literature as a skin-colored cystic tumor localized on the forehead, whereas alopecic and aseptic nodules of the scalp are described in the French literature as asymptomatic nodules on the scalp that lack a pseudocyst-like architecture. The etiology of these diseases is unknown, but the lesions are likely due to follicular occlusion. Here, we report a case of pseudocyst of the scalp in a 72-year-old woman. The patient had a dome-shaped painless tumor on her scalp. Histologic examination showed a pseudocyst-like architecture with no true cystic wall. Here, we report a case of pseudocyst of the scalp and summarize the characteristic features of both pseudocyst of the scalp and alopecic and aseptic nodules of the scalp.