Adjacent Non-lesional Skin Research Articles

TFCP2L1 as a potential diagnostic gene biomarker of Keloid given its association with immune cells-a study based on machine learning and RNA sequence

Keloids represent a specific type of dermal tumor, where delayed treatment greatly heighten risks of recurrence. This study thus seeks to identify key genes for early keloid diagnosis and compare how immune cell infiltration between keloid lesion skin (KLS) and keloid adjacent non-lesional skin (KNL) differ. Utilizing two GEO datasets, which encompassed KLS (n=8) and KNL (n=6) samples, 564 differentially expressed genes (DEGs) were identified, with a primary emphasis on inflammation- and fibrosis-related pathways. The gene TFCP2L1 was pinpointed from the intersection of LASSO and SVM-RFE algorithms, exhibiting downregulation in KLS when juxtaposed with KNL. To aid prognosis and identification of potential immunotherapy targets, the CIBERSORT algorithm was employed to assess prelative proportions of immune cells. In the KNL samples, there was an observed increase in follicular helper T cells, activated NK cells, and activated dendritic cells. Conversely, M1 macrophages were elevated in KLS samples. TFCP2L1 exhibited a positive correlation with activated NK cells and activated dendritic cells, while it showed a negative correlation with M1macrophages. These findings highlight the intertwined roles of TFCP2L1 and immune cell infiltration, lending to TFCP2L1’s potential as a diagnostic biomarker for keloids and highlights how TFCP2L1 might influence keloid development through immune cell populations.

Profibrotic Subsets of SPP1+ Macrophages and POSTN+ Fibroblasts Contribute to Fibrotic Scarring in Acne Keloidalis

Acne keloidalis is a primary scarring alopecia characterized by longstanding inflammation in the scalp causing keloid-like scar formation and hair loss. Histologically, acne keloidalis is characterized by mixed leukocytic infiltrates in the acute stage followed by a granulomatous reaction and extensive fibrosis in the later stages. To further explore its pathogenesis, bulk RNA sequencing, single-cell RNA sequencing, and spatial transcriptomics were applied to occipital scalp biopsy specimens of lesional and adjacent no-lesional skin in patients with clinically active disease. Unbiased clustering revealed 19 distinct cell populations, including 2 notable populations: POSTN+ fibroblasts with enriched extracellular matrix signatures and SPP1+ myeloid cells with an M2 macrophage phenotype. Cell communication analyses indicated that fibroblasts and myeloid cells communicated by SPP1 signaling networks in lesional skin. A reverse transcriptomics in silico approach identified corticosteroids as possessing the capability to reverse the gene expression signatures of SPP1+ myeloid cells and POSTN+ fibroblasts. Intralesional corticosteroid injection greatly reduced SPP1 and POSTN gene expression as well as acne keloidalis disease activity. Spatial transcriptomics and immunofluorescence staining verified microanatomic specificity of SPP1+ myeloid cells and POSTN+ fibroblasts with disease activity. In summary, the communication between POSTN+ fibroblasts and SPP1+ myeloid cells by SPP1 axis may contribute to the pathogenesis of acne keloidalis.

Upregulated SKP2 Empowers Epidermal Proliferation Through Downregulation of P27 Kip1.

Excessive growth of keratinocytes is the critical event in the etiology of psoriasis. However, the underlying molecular mechanism of psoriatic keratinocyte hyperproliferation is still unclear. This study aimed to figure out the potential contributory role of S-phase kinase-associated protein 2 (SKP2) in promoting the hyperproliferation of keratinocytes in psoriasis. We analyzed microarray data (GSE41662) to investigate the gene expression of SKP2 in psoriatic lesion skins compared with their adjacent non-lesional skin. Then, we further confirmed the mRNA and protein expression of SKP2 in human psoriatic skin tissues, imiquimod (IMQ)-induced psoriatic mice back skins and tumor necrosis factor α (TNF-α), interleukin (IL)-17A and IL-6-stimulated keratinocytes by using real-time quantitative polymerase chain reaction and western blot (WB). Furthermore, we explored the potential pathogenic role and its underlying cellular mechanism of SKP2 in promoting keratinocytes hyperproliferation through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, cell cycle detection, 5-ethynyl-2'-deoxyuridine staining and WB. Finally, we determined whether inhibition of SKP2 can effectively alleviate the keratinocytes hyperproliferation in vivo. We identified that SKP2 is aberrantly upregulated in the psoriatic lesion skin and cytokines-stimulated keratinocytes. Moreover, upregulated SKP2 augments cytokines-induced keratinocytes hyperproliferation. Mechanistically, enhanced SKP2 increased the S phase ratio through inhibiting Cyclin-Dependent Kinase Inhibitor p27 (P27 Kip1) expression. Correspondingly, suppression of SKP2 with SMIP004 can significantly ease the epidermis hyperplasia in vivo. Our results suggest that elevated SKP2 can empower keratinocytes proliferation and psoriasis-like epidermis hyperplasia via downregulation of P27 Kip1. Therefore, targeting SKP2-P27 Kip1 axis might be a promising therapeutic strategy for the treatment of psoriasis in future.

Skin microbiome in atopic dermatitis: New insights from clinical trials.

Atopic dermatitis (AD) is a chronic skin inflammatory disorder, with extensive burden among both children and adults.1 Recent advances in mechanistic understanding of underlying inflammatory pathways associated with AD phenotypes have resulted in improved options for topical and systemic treatment,2 with efficacy of monotherapies (e.g. abrocitinib, baricitinib, dupilumab, lebrikizumab, nemolizumab, tralokinumab, upadacitinib) ranging from 56.7% to 83.6%.3 Progression of AD is influenced by a combination of genetic, environmental and microbial covariates, and several studies have demonstrated the potential role of skin resident microbial flora (especially the bacterium Staphylococcus aureus) in AD,4 which may also impact response to therapy. Pertinent to this topic, Rauer et al.5 present their results from microbiome analysis of skin samples collected from patients with AD in the current issue of The Journal of the European Academy of Dermatology and Venereology. The authors analyzed baseline demographic and microbiome data from 60 moderate-to-severe AD patients from a previously reported cohort in New York, USA, to investigate correlation between disease severity and composition of the skin microbiome. Skin microbiome was sampled by swabbing lesional and adjacent non-lesional skin, and characterized by sequencing hypervariable regions V1–V3 of the 16S rRNA gene. Severity of AD was determined using SCORAD (SCORing Atopic Dermatitis), the validated clinical tool used to assess the extent and severity of eczema. Rauer et al. used objective SCORAD (oSCORAD, which considers only extent and intensity of AD) to determine correlation of AD severity with microbiome. These authors reported the skin microbiome of AD patients was dominated by S. aureus, which was detected in 79% of samples and was the most abundant species in 49% of lesional and 28% of non-lesional samples. Interestingly, diversity of skin microbiome correlated with oSCORAD, with lower diversity in lesional skin compared to non-lesional skin. High AD severity was associated with low evenness (a key determinant of microbiome composition), independent of skin sampling location. These results indicate dysbiosis in the microbiome population in lesional skin. Moreover, these authors identified S. aureus as a major contributor to association of microbiome diversity with AD severity and AD-affected skin sites. Among clinical variables, ethnicity was found to be an important covariate in the association between AD severity and skin microbiome. However, given the small sample size for sub-group analysis in the study, the contribution of ethnicity to skin microbiome and AD severity warrants further investigation. While elevated levels of S. aureus in the skin microbiome of AD patients have previously been reported,4 the study by Rauer et al.5 underscores the clinical relevance of this association as the samples were collected from patients at baseline of a well-designed clinical trial. Further analysis of skin microbiome during the progression of disease is likely to shed important insight into the interplay between changes in microbial composition and response to therapy. Given these interesting findings, a reasonable next step could be inclusion of skin microbiome sampling into clinical trials as exploratory endpoints in future clinical trials of AD. This would allow assessment if the identified microbial changes are linked with patient outcomes or medication response in a controlled setting. Ultimately this may then allow patient stratification based on microbial composition. Expanding those findings beyond the microbiome, such as targeting skin fungal mycobiome or virome may also reveal new insights into the contribution of microbial populations in AD. An important clinical implication of these results is that abundance of S. aureus may be used as a surrogate for skin microbial dysbiosis, especially since this organism may be more easily measured in a clinical setting using quantitative PCR rather than complete or complex microbiome analysis. Sequencing results can subsequently be obtained to analyze the microbiome, and used as a validation tool. The current study by Rauer et al.5 highlights key relationships between the skin microbiome and severity of AD, and will greatly inform ongoing efforts to develop new personalized therapeutic options for this disease. The authors have no conflicts of interest to declare. Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Actinic lentigines from Japanese and European volunteers share similar impaired biological functions

BackgroundHyperpigmented spots develop earlier and with a higher incidence in Asian individuals compared with Europeans. Although actinic lentigines (AL) are very common, the biological events underlying their formation remain ill-defined. ObjectiveAL from Japanese volunteers were characterized through morphological and gene expression analyses. Data were then compared with published data on European volunteers. MethodsAL on hands were selected through dermoscopic imaging and pattern scoring in Japanese women. Skin biopsies of AL and adjacent non-lesional (NL) skin were processed for histology and gene expression profiling. Japanese and European studies were compared after harmonizing the data using the same mathematical and statistical methods. ResultsHistologically, AL from Japanese individuals revealed deep epidermal invaginations with melanin accumulation in the depth of epidermal rete ridges. Transcriptomic data identified 245 genes differentially expressed in AL versus NL skin samples, associated with the different skin compartments and multiple functional families and biological processes, such as epidermal homeostasis, extracellular matrix organization and ion binding/transmembrane transport. Strikingly, melanogenesis-related genes were not significantly modulated in AL compared with NL skin.Comparison of the molecular profiles of Japanese and European AL showed that a huge majority of genes were modulated in the same way, recapitulating the overall biological alterations. ConclusionAL from Japanese volunteers exhibited morphological and molecular alterations of the whole skin structure with impairment of multiple biological functions similar to that found in European women. These findings will contribute to the development of efficient treatments of AL lesions.

Circular RNA expression profile analysis of severe acne by RNA‐Seq and bioinformatics

Acne is a common chronic skin disease with a multifactorial aetiology and pathogenesis. Recently, circular RNAs (circRNAs) have been identified as a key factor in regulating gene expression through circRNA-miRNA-mRNA networks in many biological processes and human diseases. However, the circRNAs expression in patients with acne is still unknown. To investigate circRNA expression profile in severe acne. The expression profile of circRNAs in three paired lesional skin and adjacent non-lesional skin in severe acne was detected by high-throughput RNA sequencing technology and bioinformatics analysis. The candidate circRNAs were validated by PCR, Sanger sequencing and qRT-PCR in the separate group (n = 4). The circRNA-miRNA-mRNA interaction networks were predicted. A total of 538 circRNAs including 271 up- and 267 downregulated circRNAs were differentially expressed in lesional skin compared with adjacent non-lesional skin in severe acne. Gene Ontology and KEGG pathway enrichment analyses revealed that the aberrantly expressed circRNAs were primarily involved in inflammatory, metabolism and immune responses. Five candidate circRNAs (circRNA_0084927, circRNA_0001073, circRNA_0005941, circRNA_0086376 and circRNA_0018168) were validated to have significant decrease in severe acne by PCR, Sanger sequencing and qRT-PCR, in agreement with the results from RNA-Seq data analysis. The five identified circRNAs were predicted to interact with 213 miRNAs and regulated target gene expression. This study firstly showed that circRNAs were differentially expressed in severe acne and suggested that circRNAs could be used as a potential biomarker for the drug targets of acne.

Longitudinal Study of the Psoriasis-Associated Skin Microbiome during Therapy with Ustekinumab in a Randomized Phase 3b Clinical Trial

Plaque psoriasis, a chronic inflammatory disease primarily affecting the skin, is thought to have a multifactorial etiology, including innate immune system dysregulation, environmental triggers, and genetic susceptibility. We sought to further understand the role of skin microbiota in psoriasis pathogenesis, as well as their response to therapy. We systematically analyzed dynamic microbiota colonizing psoriasis lesions and adjacent nonlesional skin in 114 patients prior to and during ustekinumab treatment in a phase 3b clinical trial. By sequencing the bacterial 16S ribosomal RNA gene from skin swab samples obtained at six anatomical sites, we identified minor, site-specific differences in microbial diversity and composition between pretreatment lesional and nonlesional skin. During therapy, microbial communities within lesional and nonlesional skin diverged, and body-site dispersion increased, reflecting microbial skin site-specificity. Microbiota demonstrated greater pretreatment heterogeneity in psoriatic lesions than in nonlesional skin, and variance increased as treatment progressed. Microbiota colonizing recurrent lesions did not overlap with pretreatment lesional microbiota, suggesting colonization patterns varied between initial and recurrent psoriatic lesions. While plaque psoriasis does not appear to be associated with specific microbes and/or microbial diversity, this large dataset provides insight into microbial variation associated with (i) disease in different body locations, (ii) initial versus recurrent lesions, and (iii) anti-IL12/23 therapy.

Depletion of Epidermal Langerhans Cells in the Skin Lesions of Pellagra Patients.

Pellagra is a nutrient deficiency disease caused by insufficient niacin levels. Recent studies have shown that numbers of epidermal Langerhans cells decreased in other diseases caused by nutritional deficiencies, including necrolytic migratory erythema and acrodermatitis enteropathica. Epidermal Langerhans cells are capable of modulating or even halting the inflammatory reaction. The aim of this study was to examine changes in the number of Langerhans cells and other dendritic cells, and maturation of epidermal Langerhans cells in the lesional and adjacent non-lesional skin in pellagra patients. Seven pellagra patients and 10 healthy individuals who served as controls were included. The number and distribution of dendritic cells and other cutaneous cells were examined by immunohistochemistry. Epidermal Langerhans cells decreased considerably in the skin lesions of pellagra patients, whereas other dendritic cells did not change. The decrease in the number of Langerhans cells was positively correlated with the histological severity of skin lesions. As the number of Langerhans cells was not reduced in the undisturbed neighboring skin, the depletion of epidermal Langerhans cells did not precede skin damage but was a cause of prolonged severe inflammation.

Aberrant connective tissue differentiation towards cartilage and bone underlies human keloids in African Americans.

Keloids are benign fibroproliferative tumors more frequently found among African Americans. Until now, keloid etiopathogenesis is not fully understood. To characterize keloids in African Americans, we performed transcriptional profiling of biopsies from large chronic keloids, adjacent non-lesional (NL) skin (n=3) and a newly formed keloid lesion using Affymetrix HGU133 2.0 plus arrays. Quantitative RT-PCR (qRT-PCR) and immunohistochemistry (IHC) staining were performed to confirm increased expression of relevant genes. We identified 1202 upregulated and 961 downregulated differentially expressed genes (DEGs) between keloid and NL skin; 1819 up- and 1867 downregulated DEGs between newly formed keloid and NL skin; and 492 up- and 775 downregulated DEGs between chronic and newly formed keloid (fold change >2, false discovery rate <0.05). Many of the top upregulated DEGs between chronic keloid and NL skin and between newly formed keloid and NL skin are involved in bone/cartilage formation including Fibrillin 2 (FBN2), Collagen type X alpha 1, Asporin (ASPN), Cadherin 11 (CDH11), Bone morphogenic protein 1 (BMP1), Secreted phosphoprotein 1 and Runt-related transcription factor 2 (RUNX2). qRT-PCR confirmed significant (P<.05) upregulation of BMP1, RUNX2, CDH11 and FBN2 in chronic keloid compared to NL skin. IHC staining showed increased protein expression of ASPN, CDH11, BMP1 and RUNX2 on chronic and newly formed keloid compared to NL skin. Our study shows that large keloids in African Americans represent a dysplasia of cutaneous connective tissue towards immature cartilage or bone differentiation. The phenotype is potentially regulated by overexpression of RUNX2. This knowledge may give insights to guide the development of better treatment for the disease in the future.

Identification of Somatic KRAS Mutation in a Korean Baby with Nevus Sebaceus Syndrome

Identification of Somatic <i>KRAS</i> Mutation in a Korean Baby with Nevus Sebaceus Syndrome

Naevus sebaceus: a mosaic RASopathy

Epidermal naevi are common cutaneous mosaic disorders that occur in 0.1-0.3% of live births. They are subdivided into keratinocytic and organoid naevi, the latter including naevus sebaceus (NS). Typically, NS develops as a yellowish-orange plaque on the scalp, and represents a hamartoma containing epidermal, sebaceous and apocrine elements. The histological features of NS sampled in childhood include hyperkeratosis, acanthosis, increased sebaceous lobules, and primitive hair follicles. During puberty, most lesions develop more prominent sebaceous and apocrine components. Subsequently, secondary tumours may occur in around 25% of NS; most lesions are benign (e.g. trichoblastomas, syringocystadenoma papilliferum or other basaloid proliferations), although malignant tumours arising within NS can occur (< 1%). Recently, somatic mosaicism has been shown, with activating Ras mutations in HRAS or KRAS in NS lesional keratinocytes (but not in adjacent nonlesional skin or dermal fibroblasts). These mutations lead to constitutive activation of the RAF-MEK-ERK and phosphoinositide 3-kinase signalling pathways, and result in increased cellular proliferation. Similar but more extensive mosaicism underlies Schimmelpenning-Feuerstein-Mims syndrome. The most common mutation is c.37G>C (p.Gly13Arg) in HRAS, which is present in > 90% of NS. This mutation also seems to be present in NS cases that develop secondary tumours, although no additional mutations (second hit) or other genetic events have yet been identified. Treatment of NS often involves prophylactic surgical excision, but the recent identification of key epidermal signalling abnormalities underlying the cell proliferation means that future development of new medical treatments for NS that target the aberrant signalling pathways may also be feasible.

Altered expression of antimicrobial peptide genes in the skin of dogs with atopic dermatitis and other inflammatory skin conditions

Reports indicate that human and canine patients with atopic dermatitis (AD) have reduced production of several skin antimicrobial peptides, but more recent data have called those results into question. To compare the mRNA expression of seven antimicrobial peptide genes in lesional and adjacent nonlesional skin biopsy specimens from dogs with AD with those from normal dogs and from dogs experiencing other inflammatory skin conditions. Normal dogs and patients with AD or other inflammatory skin conditions were enrolled with owner permission and approval of the Institutional Animal Care and Use Committee. Transcripts were measured by quantitative RT-PCR using a standard curve assessment. Normal transcript levels for all seven antimicrobial peptides varied depending on the body site assessed. Transcripts for secretory leukocyte proteinase inhibitor (SLPI) and skin-derived antileucoproteinase (SKALP; also known as elafin) were typically ~10-fold greater in number than transcripts for the canine β-defensins (CBD)-1, -102, -103, -122 and -124. Transcripts for SKALP, SLPI, CBD-1, CBD-103 and CBD-122 were lower in both lesional and adjacent nonlesional skin from dogs with AD in comparison to normal skin. Transcripts were reduced to a similar extent versus normal dogs in skin of dogs with inflammatory skin conditions from both lesional and nonlesional biopsies, except for CBD-122, which was reduced only in lesional skin. Compared with normal dog skin, transcripts for CBD-102 and CBD-124 were unaffected in dogs with AD. Both SKALP and SLPI may be important contributors to skin innate immunity, but their decreased expression in AD patients does not account for increased skin infections compared with other skin conditions.

Meta-Analysis Derived (MAD) Transcriptome of Psoriasis Defines the “Core” Pathogenesis of Disease

The cause of psoriasis, a common chronic inflammatory skin disease, is not fully understood. Microarray experiments have been widely used in recent years to identify genes associated with psoriasis pathology, by comparing expression levels of lesional (LS) with adjacent non-lesional (NL) skin. It is commonly observed that the differentially expressed genes (DEGs) differ greatly across experiments, due to variations introduced in the microarray experiment pipeline. Therefore, a statistically based meta-analytic approach, which combines the results of individual studies, is warranted. In this study, a meta-analysis was conducted on 5 microarray data sets, including 193 LS and NL pairs. We termed this the Meta-Analysis Derived (MAD) transcriptome. In “MAD-5” transcriptome, 677 genes were up-regulated and 443 were down-regulated in LS skin compared to NL skin. This represents a much larger set than the intersection of DEGs of these 5 studies, which consisted of 100 DEGs. We also analyzed 3 of the studies conducted on the Affymetrix hgu133plus2 chips and found a greater number of DEGs (1084 up- and 748 down-regulated). Top canonical pathways over-represented in the MAD transcriptome include Atherosclerosis Signaling and Fatty Acid Metabolism, while several “new” genes identified are involved in Cardiovascular Development and Lipid Metabolism. These findings highlight the relationship between psoriasis and systemic manifestations such as the metabolic syndrome and cardiovascular disease. Then, the Meta Threshold Gradient Descent Regularization (MTGDR) algorithm was used to select potential markers distinguishing LS and NL skin. The resulting set (20 genes) contained many genes that were part of the residual disease genomic profile (RDGP) or “molecular scar” after successful treatment, and also genes subject to differential methylation in LS tissues. To conclude, this MAD transcriptome yielded a reference list of reliable psoriasis DEGs, and represents a robust pool of candidates for further discovery of pathogenesis and treatment evaluation.

Expression of microRNAs in basal cell carcinoma

Perturbations in the expression profiles of microRNAs (miRNAs) have been reported for a variety of different cancers. Differentially expressed miRNAs have not been systematically evaluated in basal cell carcinoma (BCC) of the skin. To initiate a microarray-based miRNA profiling study to identify specific miRNA candidates that are differentially expressed in BCC. Patients with BCC (n = 7) were included in this study. Punch biopsies were harvested from the tumour centre (lesional, n = 7) and from adjacent nonlesional skin (intraindividual control, n = 7). Microarray-based miRNA expression profiles were obtained on an Agilent platform using miRBase 16 screening for 1205 Homo sapiens (hsa)-miRNA candidates. To validate the microarray data, the expression of seven dysregulated miRNAs was measured by TaqMan quantitative real-time reverse transcription polymerase chain reaction. We identified 16 significantly upregulated (hsa-miR-17, hsa-miR-18a, hsa-miR-18b, hsa-miR-19b, hsa-miR-19b-1*, hsa-miR-93, hsa-miR-106b, hsa-miR-125a-5p, hsa-miR-130a, hsa-miR-181c, hsa-miR-181c*, hsa-miR-181d, hsa-miR-182, hsa-miR-455-3p, hsa-miR-455-5p and hsa-miR-542-5p) and 10 significantly downregulated (hsa-miR-29c, hsa-miR-29c*, hsa-miR-139-5p, hsa-miR-140-3p, hsa-miR-145, hsa-miR-378, hsa-miR-572, hsa-miR-638, hsa-miR-2861 and hsa-miR-3196) miRNAs in BCC compared with nonlesional skin. Data mining revealed connections to many tumour-promoting pathways, such as the Hedgehog and the mitogen-activated protein kinase/extracellular signal-regulated kinase signalling cascades. This study identified several miRNA candidates that may play a role in the molecular pathogenesis of BCC.

The histopathological characteristics of male melasma: Comparison with female melasma and lentigo

Knowledge of the histopathology of melasma is a prerequisite for understanding its pathogenesis. However, the histopathological characteristics of male melasma are not well characterized. We sought to investigate the histopathological characteristics of melasma in men compared with those of women with melasma and solar lentigo. Biopsy specimens were obtained from both the lesional skin and the adjacent nonlesional skin in 8 men with melasma, 10 women with melasma, and 5 men and women each with solar lentigo. The samples were stained using Fontana-Masson and Verhoeff-van Gieson. Immunohistochemistry for melanocytes, the estrogen receptor, progesterone receptor, factor VIIIa-related antigen, stem cell factor, and c-kit was performed. Increased vascularity was found in the lesion of male melasma. The lesion to nonlesion ratio of the vessel area was increased in male melasma compared with lentigo groups. In the lesion of male melasma, there was a significant increase of stem cell factor and c-kit expression. In addition, the lesion to nonlesion ratio of stem cell factor was increased in male melasma compared with female melasma and lentigo groups. The lesion to nonlesion ratio of c-kit was also increased in male melasma compared with lentigo groups. This study did not include clinical data regarding social habits and was not confirmed by other molecular techniques. The results suggest that chronic ultraviolet radiation associated with signaling of paracrine cytokines plays an important role in the mechanism associated with hyperpigmentation in male melasma.

Elevated Cutaneous Smad Activation Associates with Enhanced Skin Tumor Susceptibility in Organ Transplant Recipients

Nonmelanoma skin cancer incidence is enhanced >50-fold in patients taking antirejection drugs (ARD) following organ transplantation. Preclinical studies suggest that ARD treatment increases transforming growth factor-beta1 (TGF-beta1) levels, which contribute to enhanced tumor susceptibility independent of the immunosuppressive effects of ARDs. This study investigates whether TGF-beta signaling is elevated in transplant patients. Immunohistochemical tissue microarray analysis was used to determine the levels of TGF-beta1, TGF-beta2, TGF-beta3, TbetaRII, and activated P-Smad2/3 and P-Smad1/5/8, which are phosphorylated directly by distinct TGF-beta/BMP receptor complexes. We analyzed >200 cutaneous lesions and adjacent nonlesional skin samples from 87 organ transplant recipients, and 184 cutaneous lesions and adjacent skin samples from 184 individuals who had never received ARDs. We found significantly higher levels of P-Smad2 in both nonlesional and lesional tissue from transplant recipients compared with those not exposed to ARDs (P < or = 0.001). In contrast, P-Smad1/5/8, a marker of activation of the bone morphogenetic protein signaling pathway, was generally not expressed at higher levels in patients taking ARDs, including analysis of nonlesional skin, actinic keratoses, carcinoma in situ, or squamous cell carcinoma but was differentially expressed between keratoacanthoma from transplant recipients compared with those from non-transplant recipients (P < or = 0.005). Observation of elevated P-Smad2 levels in transplant recipients is consistent with the notion that elevated TGF-beta signaling may contribute to malignancy in organ transplant recipients. Disparate P-Smad1/5/8 expression levels between keratoacanthoma from the two patient groups might reflect the distinct BMP-responsive cell of origin for this hair follicle-derived lesion.

In vivo optical coherence tomography of basal cell carcinoma

Optical coherence tomography (OCT) is a promising non-invasive imaging technique that has not systematically been studied in skin cancer such as basal cell carcinoma (BCC). We aimed, first, to describe the in vivo histologic features of BCC by using OCT, and second, to find out whether it is possible to differentiate BCC subtypes by means of OCT. Prior to the excision, the BCCs (n=43) as well as adjacent non-lesional skin sites were assessed by OCT in vivo. The lesional area of interest was marked prior to OCT and tattooed after excision, respectively, in order to enable topographical concordance between the cross-sectional OCT images and the histologic sections. Compared to non-lesional skin, a loss of normal skin architecture and disarrangement of the epidermis and upper dermis was observed in the OCT images of BCCs. Features that were frequently identified by OCT and correlated with histology included large plug-like signal-intense structures, honeycomb-like signal-free structures, and prominent signal free cavities in the upper dermis. With regard to the aforementioned OCT features, no statistically significant (P<0.05) difference was found between nodular, multifocal superficial, and infiltrative BCCs, respectively. OCT is capable to visualize altered skin architecture and histopathological correlates of BCC. However, there is not at this time sufficient data supporting the clinical use of OCT for the differentiation of BCC subtypes.

HIGH RATES OF APOPTOSIS IN HUMAN MYCOBACTERIUM ULCERANS CULTURE-POSITIVE BURULI ULCER SKIN LESIONS

Buruli ulcer, a disease caused by Mycobacterium ulcerans, causes ulcerative skin disease likely generated by a toxin that mediates apoptosis. We analyzed paraffin-embedded sections of surgically excised Buruli ulcer lesions (two ulcers and one edematous plaque) and adjacent non-lesional skin samples (n = 9) for apoptosis by an indirect immunofluorescent terminal deoxynucleotide transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) assay. All samples were stained for acid-fast bacilli (AFB) and cultured for mycobacteria, and most were analyzed with an M. ulcerans-specific diagnostic polymerase chain reaction (PCR). TUNEL (+) bodies were numerous in both ulcers and the plaque, and sparse or absent in adjacent non-lesional skin. The AFB tissue stains and cultures for M. ulcerans were positive only in the three lesions. The result of the PCR for M. ulcerans was positive in all three lesions and in four of six non-lesional tissue samples; three contained sparse TUNEL (+) bodies. An abundance of TUNEL (+) bodies in the three AFB stain (+), culture (+), and PCR (+) Buruli ulcer lesional samples, but not in nearby AFB stain (-), culture (-), and PCR (+) non-lesional skin samples, strengthen the evidence that apoptosis is an important tissue destruction mechanism in human lesions closely associated with viable M. ulcerans.

Cutaneous expression of cytochrome P450 CYP2S1: individuality in regulation by therapeutic agents for psoriasis and other skin diseases

Treatment of common skin diseases such as psoriasis is complicated by differences between individuals in response to topical drug treatment and photochemotherapy. Individuality in hepatic expression of drug-metabolising enzymes is an important determinant of systemic drug handling; we investigated whether similar variation in cutaneous gene expression contributes to individuality in response to topical therapies. We used quantitative real-time RT-PCR to demonstrate the expression in skin of a recently identified cytochrome P450, CYP2S1, in healthy volunteers (n=27) and patients with psoriasis (n=29). We also investigated regulation of CYP2S1 by ultraviolet radiation, psoralen-ultraviolet A (PUVA), and topical drugs used to treat psoriasis. We found that CYP2S1 is expressed in skin and showed pronounced individuality in constitutive expression of the enzyme and its induction after ultraviolet irradiation or topical drug treatment. Cutaneous expression of CYP2S1 was induced by ultraviolet radiation, PUVA, coal tar, and all-trans retinoic acid; expression was significantly higher in lesional psoriatic skin than in adjacent non-lesional skin (geometric mean 3.38 [95% CI 2.64-4.34] times higher; p<0.0001), which implies that topical drugs are differentially metabolised in psoriatic plaque and non-lesional skin. We showed that all-trans retinoic acid is metabolised by CYP2S1, which has higher cutaneous expression than CYP26, previously described as the specific cutaneous P450 retinoic-acid-metabolising enzyme. These findings increase our understanding of the interaction between therapeutic agents and the skin and suggest a functional role for CYP2S1 in the metabolism of topical drugs and in mediating the response to photochemotherapy in psoriasis.

Dermatofibroma is a clonal proliferative disease.

Benign fibrous histiocytoma of the skin or dermatofibroma (DF) has been regarded as a fibrohistiocytic tumor. Whether DF is a neoplastic growth or a reactive process has not been settled. Since a neoplastic process is clonal in nature, clonal analysis of DF was conducted to see if DF is a clonal disease. Fresh specimens of 13 DFs and 2 hypertrophic scars obtained from female patients were studied. The adjacent nonlesional skin tissues served as controls. The clonal analysis was based on the methylation pattern of the polymorphic X-chromosome linked androgen-receptor gene (HUMARA). Eight DFs and 1 hypertrophic scar were heterozygous at the androgen receptor gene and could be analyzed. All 8 informative DFs showed a significant reduction in one of the allelic bands compared with the corresponding bands of the nonlesional tissue after Hha I digestion. Therefore, DF is a clonal proliferative disease. In contrast, 1 hypertrophic scar showed a polyclonal pattern of X-chromosome inactivation. We conclude that DF is a clonal disease favoring a neoplastic process.