Retraction: Ampelopsis japonica Makino Extract Inhibits the Inflammatory Reaction Induced by Pathogen-Associated Molecular Patterns in Epidermal Keratinocytes

This article has been retracted following a review by the Editorial Board.

Ampelopsis japonica Makino Extract Inhibits the Inflammatory Reaction Induced by Pathogen-Associated Molecular Patterns in Epidermal Keratinocytes

BACKGROUND: Keratinocytes are the major cells in epidermis, providing barrier components such as cornified cells through the sophisticated differentiation process. In addition, keratinocytes exerts their role as the defense cells via activation of innate immunity. It has been known that pathogen-associated molecular patterns (PAMPs) including double-strand RNA and nucleotides can provoke inflammatory reaction in keratinocytes. OBJECTIVE: The aim of this study is to evaluate the effect of Ampelopsis japonica Makino extract (AE) on PAMPs-induced inflammatory reaction of keratinocytes. METHODS: The effects of AE were determined using poly (I:C)-induced inflammation and imiquimod-induced psoriasiform dermatitis models. RESULTS: In cultured keratinocytes, AE significantly inhibited poly(I:C)-induced expression of inflammatory cytokines, such as interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor-α. AE significantly inhibited poly(I:C)-induced release of caspase-1 active form (p20), and down-regulated nuclear factor-κB signaling pathway. In imiquimod-induced psoriasiform dermatitis model, topical application of AE resulted in significant reduction of epidermal hyperplasia. CONCLUSION: These results suggest that AE may be a potential candidate for the treatment of skin inflammation.

Induction of Interleukin-22 (IL-22) production in CD4+ T Cells by IL-17A Secreted from CpG-Stimulated Keratinocytes

BACKGROUND: Interleukin-17A (IL-17A) is mainly secreted from Th17 cells that are activated by various stimuli including CpG oligodeoxynucleotide, a Toll-like receptor 9 (TLR9) ligand. Recently, it has been demonstrated that keratinocytes play an important role in the pathogenesis of psoriasis. OBJECTIVE: To investigate the potential role of keratinocytes, we examined whether TLR9 ligand CpG induces IL-17A expression in keratinocytes. METHODS: We used HaCaT keratinocytes as a model system, and determined CpG-induced IL-17A using enzyme-linked immunosorbent assay and Western blot. RESULTS: When HaCaT keratinocytes were treated with CpG, the expression of several cytokines including IL-17A, tumor necrosis factor-α and CCL20 was markedly increased. Treatment with nuclear factor (NF)-κB inhibitor significantly blocked the CpG-induced IL-17A production, indicating that CpG induced IL-17A expression through the NF-κB signaling pathway. In addition, IL-17A secreted from keratinocytes stimulated the CD4⁺ T cells, resulting in strong induction of IL-22 production. CONCLUSION: Since IL-22 is an important mediator for psoriatic inflammation, our data suggest that keratinocytes can participate in the pathogenesis of psoriasis via the TLR9-dependent IL-17A production.

Stimulation of keratinocyte differentiation by extract of combined medicinal plant / 동물의과학연구지

Skin is the outermost organ and acts as a barrier between the organism and environment. Skin protects the organism from environmental insults, such as chemicals, pathogens, and UV light. Much of the protective function of skin is dependent on the epidermis, a multi-layered epithelium that is composed of various cell types such as keratinocytes and melanocytes. Keratinocytes produce protective components through a sophisticated differentiation process. Disturbance of keratinocyte differentiation is related to several skin diseases such as psoriasis and atopic dermatitis. In this study, we prepared extract of combined medicinal plants (ECMP) consisting of Taraxacum platycarpum H. Dahlstedt, Heartleaf Houttuynia, Glycyrrhiza uralensis Fischer, and root bark of Ulmus davidiana. We demonstrated that ECMP enhanced keratinocyte differentiation and barrier functionality using an in vitro cell culture system and in vivo animal test. Treatment of cultured keratinocytes with ECMP resulted in induction of keratinocyte differentiation, as evidenced by increased differentiation markers such as involucrin, loricrin, and filaggrin. In line with these results, ECMP decreased proliferation of keratinocytes cultured in vitro. ECMP applied topically to tape-stripped mouse skins accelerated reduction of transepidermal water loss (TEWL), indicating fast recovery of barrier function. Immunohistochemistry showed that ECMP increased the filaggrin level in tape-stripped mouse skins. These results suggest that ECMP may be applicable for keratinocyte differentiation-related skin diseases.

Immunohistochemical Study of O-GlcNAcylation in Human Skin Tumors / 체질인류학회지

O-linked beta-N-acetylglucosamine modification is an important post-translational modification, emerging as a novel regulatory mechanism in various cellular events. Recently, several studies have shown that O-GlcNAcylation plays an essential role in human breast, lung, and colon cancers. With regard to skin cancers, the role of O-GlcNAcylation has yet to be elucidated. To investigate whether O-GlcNAcylation is linked to human skin tumor development, immunohistochemical analysis was performed to investigate the presence of O-GlcNAcylation in various skin tumors. We evaluated the levels of O-GlcNAcylation, O-GlcNAc transferase, and O-GlcNAcase in 29 benign tumors, 12 premalignant tumors, and 26 malignant tumors in skin. Compared to the benign tumors, premalignant and malignant tumors had increased patterns of O-GlcNAcylation. In addition, the O-GlcNAc transferase and O-GlcNAcase levels were higher in premalignant and malignant tumors than in benign tumors. Interestingly, O-GlcNAcase levels were significantly increased in premalignant tumors compared to benign and malignant tumors. These results suggest that O-GlcNAcylation of proteins may play an important role in the development of human skin tumors.

Comparison of Gene Expression Profiles between Keratinocytes, Melanocytes and Fibroblasts

BACKGROUND: The skin has many important functions such as protection, preservation, temperature regulation, and vitamin D synthesis. It is composed of a variety of cell types including keratinocytes, melanocytes and fibroblasts. OBJECTIVE: We attempted to compare the gene expression profiles between keratinocytes, melanocytes and fibroblast, using cDNA microarray. METHODS: Keratinocytes, melanocytes and fibroblasts were primary cultured from five foreskin specimens. Total RNAs were extracted and pooled to reduce the individual variations, and then used for cDNA microarray. RESULTS: Total 12,028 genes were selected as the reliable genes whose expression was detected in at least one of the three cell types. By comparing the relative expression levels with cutoff limitation as a fourfold change, we obtained 126 fibroblast-specific, 179 keratinocyte-specific and 173 melanocyte-specific genes, many of which are known to be characteristically expressed in each cell type. In addition, we identified many genes whose skin-specific functions have not yet been determined. CONCLUSION: Our data provide important information on which to base further investigation into the specification of skin cell types.

Changes in Transepidermal Water Loss and Skin Hydration according to Expression of Aquaporin-3 in Psoriasis

BACKGROUND: Aquaporins (AQPs) are a family of water transporting proteins present in many mammalian epithelial and endothelial cell types. Among the AQPs, AQP3 is known to be a water/glycerol transporter expressed in human skin. OBJECTIVE: The relationship between the expression level of AQP3 and transpidermal water loss (TEWL) in the lesional and peri-lesional skin of psoriasis-affected patients, and skin hydration in the lesional and peri-lesional skin of psoriasis patients, was investigated. METHODS: The expression of AQP3 in psoriasis-affected and healthy control skin was determined using immunohistochemical and immunofluroscence staining. TEWL and skin hydration were measured using a Tewameter(R) TM210 (Courage & Khazaka, Cologne, Germany) and a Corneometer(R) CM 820 (Courage & Khazaka), respectively. RESULTS: AQP3 was mainly expressed in the plasma membrane of stratum corneum and the stratum spinosum in normal epidermis. Unlike the normal epidermis, AQP3 showed decreased expression in the lesional and peri-lesional epidermis of psoriasis. TEWL was increased, and skin hydration was decreased, in the lesional and peri-lesional skin of psoriasis patients, compared with the healthy control sample. CONCLUSION: Although various factors contribute to reduced skin hydration in the lesional and peri-lesional skin of psoriasis, AQP3 appears to be a key factor in the skin dehydration of psoriasis-affected skin.

Epigenetic Modulation of Gene Expression during Keratinocyte Differentiation

BACKGROUND: Epigenetic modulation of gene expression occurs by various methods, including DNA methylation and histone modification. DNA methylation of specific genes may affect the chromatin structure, preventing access by the transcriptional machinery. Although gene expression is dramatically changed during keratinocyte differentiation, there is no evidence of epigenetic modulation during the process of epidermal stratification. OBJECTIVE: We investigated whether epigenetic modulation is involved in keratinocyte differentiation-specific gene regulation. METHODS: We used trypsin to produce epidermal fragmentation (named T1-T4) and performed a morphological analysis using hematoxylin-eosin stain and cytokeratin expression based on reverse transcription polymerase chain reaction. We then constructed a DNA methylation microarray. RESULTS: Each epidermal fragment showed morphological features of the epithelial layer. T1 represented the basal layer, T2 was the spinous layer, T3 was the granular layer, and T4 was the cornified layer. The level of the K14 proliferation marker was increased in the T1 fraction, and the level of K10 differentiation marker was increased in the T2-T4 fractions. Using a methylation microarray with the T1 and T4 fractions, we obtained many hypermethylated and hypomethylated genes from differentiated keratinocytes. CONCLUSION: The importance of epigenetic modulation in target gene expression during keratinocyte differentiation is identified.

Enhancement of Keratinocyte Differentiation by Rose Absolute Oil

BACKGROUND: Through differentiation processes, keratinocytes provide a physical barrier to our bodies and control skin features such as moisturization, wrinkles and pigmentation. Keratinocyte differentiation is disturbed in several skin diseases such as psoriasis and atopic dermatitis. OBJECTIVE: The aim of this study is to evaluate the keratinocyte differentiation-enhancing effect of rose absolute oil (RAO). METHODS: Primary cultured human normal keratinocytes were treated with RAO, and differentiation then checked by the expression of marker genes. RESULTS: RAO did not induce cytotoxicity on cultured keratinocytes at a dose of 10microM. The level of involucrin, an early marker for keratinocyte differentiation, was significantly increased by RAO. Concomitantly, RAO increased involucrin promoter activity, indicating that RAO increased involucrin gene expression at the mRNA level. Furthermore, RAO increased the level of filaggrin in cultured keratinocytes, and in the granular layer of mouse skin. In line with these results, RAO decreased the proliferation of keratinocytes cultured in vitro. When RAO was applied topically on the tape-stripped mouse skins, it accelerated the recovery of disturbed barrier function. CONCLUSION: These results suggest that RAO may be applicable for the control of skin texture and keratinocyte differentiation-related skin diseases.

Effects of Calcium on the Epidermis in a Skin Organ Culture / 대한피부과학회지

BACKGROUND: Calcium plays a role in the proliferation and differentiation of keratinocytes. In a normal situation, the calcium concentration forms a gradient across the epidermal layers. Calcium is sparse in the basal layer and spinous layer. Skin organ culture is a useful model for conducting research on various aspects of skin biology. Skin organ culture systems are used for defining factors that affect homeostasis when elucidating the modulatory effects of biologic response modifiers, drugs and physical agents on the skin and also when studying complex aspects of cutaneous biology in normal and diseased skin. OBJECTIVE: In this study, we investigated the effects of extracellular calcium on the epidermis in a skin organ culture. METHODS: We compared the skin organ culture patterns under various culture conditions (calcium 0.1, 0.7, 1.4 and 2.0 mM). RESULTS: H&E staining showed different phenotypes according to the calcium concentration and IHC also showed different phenotyes compared to that of keratin 10, involucrin, filaggrin, loricrin and PCNA. CONCLUSION: As a result, we concluded that the calcium gradient is also an important factor in skin organ culture to maintain the vivo-like environment and the appropriate calcium concentration is 1.4 mM.

The Role of Nkx2.5 in Keratinocyte Differentiation

BACKGROUND: Nkx2.5 is a homeodomain-containing nuclear transcription protein that has been associated with acute T-lymphoblastic leukemia. In addition, Nkx2.5 has an essential role in cardiomyogenesis. However, the expression of Nkx2.5 in the skin has not been investigated. OBJECTIVE: In an attempt to screen the differentially regulated genes involved in keratinocyte differentiation, using a cDNA microarray, we identified Nkx2.5 as one of the transcription factors controlling the expression of proteins associated with keratinocyte differentiation. METHODS: To investigate the expression of Nkx2.5 during keratinocyte differentiation, we used a calcium-induced keratinocyte differentiation model. RESULTS: RT-PCR and Western blot analysis revealed that the expression of Nkx2.5, in cultured human epidermal keratinocytes, increased with calcium treatment in a time-dependent manner. In normal skin tissue, the expression of Nkx2.5 was detected in the nuclei of the keratinocytes in all layers of the epidermis except the basal layer by immunohistochemistry. In addition, the expression of Nkx2.5 was significantly increased in psoriasis and squamous cell carcinoma, but was barely detected in atopic dermatitis and basal cell carcinoma. CONCLUSION: These results suggest that Nkx2.5 may play a role in the change from proliferation to differentiation of keratinocytes and in the pathogenesis of skin disease with aberrant keratinocyte differentiation.

A Case of Thermal Keratosis along with Erythema Ab Igne / 대한피부과학회지

We report a case of thermal keratosis with erythema ab igne which occurred on the dorsal side of a patient's left hand due to chronic exposure to infrared rays. A 62-year-old male presented with reticular hyperpigmentation on the dorsal side of his left hand and left knee along with multiple hyperkeratotic nodules on the dorsal side of his left hand without any symptoms. He had a hobby of playing internet games with a heater on his left side. A skin biopsy of the hyperkeratotic lesion showed hyperkeratosis and acanthosis in the epidermis. The dermis revealed many elastic fibers and superficial perivascular monocytic infiltration. The patient was diagnosed with thermal keratosis and erythema ab igne due to his history of chronic infrared exposure, distinctive clinical characteristics and the biopsy results. The application of topical steroid with the recommendation to cease exposure to heaters resulted in the almost disappearance of the papules and a little restoration of the skin color.