High-fat diet induces a predisposition to follicular hyperkeratosis and neutrophilic folliculitis in mice.

BACKGROUND: Neutrophilic folliculitis is an inflammatory condition of hair follicles. In some neutrophilic folliculitis, such as in patients with acne and hidradenitis suppurativa, follicular hyperkeratosis is also observed. Neutrophilic folliculitis is often induced and/or exacerbated by a high-fat diet (HFD). However, the molecular mechanisms by which an HFD affects neutrophilic folliculitis are not fully understood. OBJECTIVE: Our aim was to elucidate how an HFD promotes the development of neutrophilic folliculitis. METHODS: Mice were fed an HFD, and their skin was subjected to histologic, RNA sequencing, and imaging mass spectrometry analyses. To examine the effect of an HFD on neutrophil accumulation around the hair follicles, phorbol 12-myristate 13-acetate (PMA) was used as an irritant to the skin. RESULTS: Histologic analysis revealed follicular hyperkeratosis in the skin of HFD-fed mice. RNA sequencing analysis showed that genes related to keratinization, especially in upper hair follicular keratinocytes, were significantly upregulated in HFD-fed mice. Application of PMA to the skin induced neutrophilic folliculitis in HFD-fed mice but not in mice fed a normal diet. Accumulation of neutrophils in the skin and around hair follicles was dependent on CXCR2 signaling, and CXCL1 (a CXCR2 ligand) was produced mainly by hair follicular keratinocytes. Imaging mass spectrometry analysis revealed an increase in fatty acids in the skin of HFD-fed mice. Application of these fatty acids to the skin induced follicular hyperkeratosis and caused PMA-induced neutrophilic folliculitis even in mice fed a normal diet. CONCLUSION: An HFD can facilitate the development of neutrophilic folliculitis with the induction of hyperkeratosis of hair follicles and increased neutrophil infiltration around the hair follicles via CXCR2 signaling.

Effects of topical application of Astragalus membranaceus on allergic dermatitis.

Astragalus membranaceus (AM) is one of the most popular health-promoting herbs in East Asia, and has been used in traditional medicine for more than 2000 years. This study was performed to examine whether AM suppresses atopic dermatitis (AD)-like skin lesions in BALB/c mice. Seven-week-old female BALB/c mice were sensitized with 1-chloro-2,4-dinitrobenzene (DNCB) to induce allergic dermatitis. Skin sections were stained with hematoxylin and eosin (H&E) to assess epidermal and dermal hyperplasia, which were determined by measuring the thicknesses of the epidermis and dermis, respectively. The serum immunoglobulin G (IgE) concentration was quantified by enzyme-linked immunosorbent assay (ELISA). In addition, the levels of interleukins (IL)-4, -5, -6, and -13 and tissue necrosis factor (TNF)-α were measured in mouse serum. Significance was determined by one-way analysis of variance (ANOVA). Topical AM markedly improved the AD skin lesions in DNCB-induced mice. The AD skin lesions were significantly thinner in the AM treatment group compared with untreated controls, and the hyperkeratosis disappeared. Topical treatment of AM also restored nuclear factor-κB (NF-κB) expression. In addition, the serum IgE level was reduced. AM suppressed the expression of Th2 cytokines (IL-4, -5, -6, and -13) and significantly decreased the TNF-α level. AM is effective for treating AD by regulating cytokines. AM may be an alternative or complementary therapeutic option for treating patients with AD. More in-depth studies are necessary to clarify the mechanisms of AM.

Disseminated epidermolytic acanthoma with disseminated superficial porokeratosis and verruca vulgaris in an immunosuppressed patient.

A 40-year-old man who had received long term immunosuppressive treatment for 14 years following kidney transplantation developed multiple skin lesions on both antecubital fossae, scalp, and both lower extremities. Histopathologic findings from three skin regions revealed characteristic features of epidermolytic hyperkeratosis, verruca vulgaris, and disseminated superficial porokeratosis, respectively. Although immunocompromised individuals may demonstrate verruca vulgaris or porokeratosis, disseminated epidermolytic acanthoma (DEA) has not been reported to be associated with immunosuppressed status. We suggest that immunosuppression may play a role in the pathogenesis of DEA, as shown in our case.

[Elastosis perforans serpiginosa. Considerations on the pathogenesis based on a typical case]. / Elastosis perforans serpiginosa. Uberlegungen zur Pathogenese anhand eines typischen Falles.

Elastosis perforans serpiginosa (EPS) is a rare entity belonging to the group of primary perforating dermatoses. A 13-year-old male patient with Down's syndrome developed reddish hyperkeratotic papules in a serpiginous and ellipsoid configuration on the face. Histological examination revealed transepidermal elimination of thick coarse elastic fibres from the papillary dermis. The dermal infiltrate showed an immunohistological pattern consistent with an acute cell-mediated immune response. It consisted mainly of activated T-lymphocytes, with a predominance of CD4-positive cells. Considerable numbers of CD1-positive cells were also present. Inflammatory macrophages of the 27E10 phenotype were found in considerable numbers, whereas 25F9-positive resident macrophages were almost completely absent. The role of a cell-mediated immune response in the mechanism of transepithelial elimination is discussed.