Unique microRNAs appear at different times during the course of a delayed-type hypersensitivity reaction in human skin.

Diphencyprone (DPCP) is a hapten that induces delayed-type hypersensitivity (DTH) reactions. MicroRNAs (miRNAs) are short non-coding RNAs that negatively regulate gene expression and have been implicated in various inflammatory skin diseases, but their role in DTH reactions is not well understood. We generated global miRNA expression profiles (using next-generation sequencing) of DPCP reactions in skin of seven healthy volunteers at 3, 14 and 120 days after challenge. Compared to placebo-treated sites, DPCP-challenged skin at 3 days (peak inflammation) had 127 miRNAs significantly deregulated. At 14 days (during resolution of inflammation), 43 miRNAs were deregulated and, at 120 days (when inflammation had completely resolved), six miRNAs were upregulated. While some miRNAs have been observed in psoriasis or atopic dermatitis, most of the deregulated miRNAs have not yet been studied in the context of skin biology or immunology. Across the three time points studied, many but not all miRNAs were uniquely expressed. As various miRNAs may influence T cell activation, this may indicate that the miRNAs exclusively expressed at different time points function to promote or resolve skin inflammation, and therefore, may inform on the paradoxical ability of DPCP to treat both autoimmune conditions (alopecia areata) and conditions of ineffective immunity (melanoma).

Laser capture microdissection followed by next-generation sequencing identifies disease-related microRNAs in psoriatic skin that reflect systemic microRNA changes in psoriasis.

Psoriasis is a systemic disease with cutaneous manifestations. MicroRNAs (miRNAs) are small non-coding RNA molecules that are differentially expressed in psoriatic skin; however, only few cell- and region-specific miRNAs have been identified in psoriatic lesions. We used laser capture microdissection (LCM) and next-generation sequencing (NGS) to study the specific miRNA expression profiles in the epidermis (Epi) and dermal inflammatory infiltrates (RD) of psoriatic skin (N = 6). We identified 24 deregulated miRNAs in the Epi and 37 deregulated miRNAs in the RD of psoriatic plaque compared with normal psoriatic skin (FCH > 2, FDR < 0.05). Interestingly, 9 of the 37 miRNAs in RD, including miR-193b and miR-223, were recently described as deregulated in circulating peripheral blood mononuclear cells (PBMCs) from patients with psoriasis. Using flow cytometry and qRT-PCR, we found that miR-193b and miR-223 were expressed in Th17 cells. In conclusion, we demonstrate that LCM combined with NGS provides a robust approach to explore the global miRNA expression in the epidermal and dermal compartments of psoriatic skin. Furthermore, our results indicate that the altered local miRNA changes seen in the RD are reflected in the circulating immune cells, suggesting that miRNAs may contribute to the pathogenesis of psoriasis.

In-Depth Proteomic Map of Innate Lymphoid Cells from Healthy Human Skin and Blood.

Innate lymphoid cells (ILCs) are essential players in the skin-associated immune system, nevertheless little is known about their proteomes and proteomic diversity. In this study, we describe about 6,600 proteins constitutively expressed by ILC2s and ILC3s from healthy human skin and blood using state-of-the-art proteomics. Although the vast majority of proteins was expressed by both ILC subsets and in both compartments, the skin ILC2s and ILC3s were more distinct than their counterparts in blood. Only skin ILC3s expressed uniquely detected proteins. Our in-depth proteomic dataset allowed us to define the cluster of differentiation marker profiles of the ILC subsets, explore distribution and abundance of proteins known to have immunological functions, as well as identify subset-specific proteins that have not previously been implicated in ILC biology. Taken together, our analyses substantially expand understanding of the protein expression signatures of ILC subsets. Going forward, these proteomic datasets will serve as valuable resources for future studies of ILC biology.

Diagnostic microRNA profiling in cutaneous T-cell lymphoma (CTCL).

Cutaneous T-cell lymphomas (CTCLs) are the most frequent primary skin lymphomas. Nevertheless, diagnosis of early disease has proven difficult because of a clinical and histologic resemblance to benign inflammatory skin diseases. To address whether microRNA (miRNA) profiling can discriminate CTCL from benign inflammation, we studied miRNA expression levels in 198 patients with CTCL, peripheral T-cell lymphoma (PTL), and benign skin diseases (psoriasis and dermatitis). Using microarrays, we show that the most induced (miR-326, miR-663b, and miR-711) and repressed (miR-203 and miR-205) miRNAs distinguish CTCL from benign skin diseases with > 90% accuracy in a training set of 90 samples and a test set of 58 blinded samples. These miRNAs also distinguish malignant and benign lesions in an independent set of 50 patients with PTL and skin inflammation and in experimental human xenograft mouse models of psoriasis and CTCL. Quantitative (q)RT-PCR analysis of 103 patients with CTCL and benign skin disorders validates differential expression of 4 of the 5 miRNAs and confirms previous reports on miR-155 in CTCL. A qRT-PCR-based classifier consisting of miR-155, miR-203, and miR-205 distinguishes CTCL from benign disorders with high specificity and sensitivity, and with a classification accuracy of 95%, indicating that miRNAs have a high diagnostic potential in CTCL.

CD4(+) T cells producing interleukin (IL)-17, IL-22 and interferon-γ are major effector T cells in nickel allergy.

BACKGROUND: It has been suggested that interleukin (IL)-17 and IL-22 play important roles in the elicitation of human allergic contact dermatitis; however, the frequencies of T cell subtypes producing IL-17 and IL-22 in human allergic contact dermatitis are unknown. OBJECTIVES: To determine the frequencies of CD4(+) , CD8(+) and γδ T cells producing IL-17, IL-22 and interferon (IFN)-γ in the blood and skin from nickel-allergic patients. PATIENTS/MATERIALS/METHODS: Blood samples were collected from 14 patients and 17 controls, and analysed by flow cytometry. Biopsies were taken from 5 patients and 6 controls, and analysed by immunohistochemistry and flow cytometry of skin lymphocytes. RESULTS: We found an increased frequency of γδ T cells in the blood, but no differences in the distribution of cytokine-producing CLA(+) T cell subtypes in nickel-allergic patients as compared with controls. In nickel-allergic patients, there was massive cellular infiltration dominated by CD4(+) T cells producing IL-17, IL-22 and IFN-γ in nickel-challenged skin but not in vehicle-challenged skin. CONCLUSION: CD4(+) T cells producing IL-17, IL-22 and IFN-γ are important effector cells in the eczematous reactions of nickel-induced allergic contact dermatitis in humans.

The Proteome of Hand Eczema Assessed by Tape Stripping.

Hand eczema (HE) is a prevalent skin disease. However, the classification of HE into different subtypes remains challenging. A limited number of previous studies have employed invasive biopsy-based strategies; yet, studies of the HE proteome using noninvasive tape-stripping methodology have not been reported. In this study, we wanted to assess whether global proteomic analysis of skin tape strip samples can be used for subclassification of patients with HE. Tape strips were collected from patients with HE and healthy skin. Liquid chromatography-mass spectrometry proteomics was performed, and the global protein expression was analyzed. We identified 2,919 proteins in stratum corneum-derived skin cells from tape strip samples. Compared with healthy skin, the lesional samples from patients with HE exhibited increased expression of immune-related markers and a decreased expression of structural barrier proteins. The difference between HE subtypes was restricted to the lesional skin areas and included an increased expression of skin barrier-related proteins independently of the concurrent AD. In conclusion, we found that the noninvasive tape strip method used in combination with liquid chromatography-mass spectrometry proteomics can be used for analysis of skin protein expression in patients with HE. Thus, the method shows potential for assessing the proteomic differences between subtypes of HE and biomarker discovery.

Comparison of microRNA expression using different preservation methods of matched psoriatic skin samples.

MicroRNAs are non-coding RNA molecules modulating gene expression post-transcriptionally. Formalin-fixed, paraffin-embedding (FFPE) is a standard preservation method often used in clinical practices, but induces RNA degradation. Extracting high-quality RNA from human skin can be challenging as skin contains high levels of RNases. As microRNAs are 19-23 nucleotides long and lack a poly-A tail, they may be less prone to RNA degradation than mRNAs. We investigated whether microRNAs in psoriatic (FFPE) samples reliably reflect microRNA expression in samples less prone to RNA degradation such as fresh-frozen (FS) and Tissue-Tek-embedding (OCT). We found a strong correlation of the microRNA expression levels between all preservation methods of matched psoriatic skin samples (r(s) ranging from 0.91 to 0.95 (P < 0.001)). These observations were further confirmed with qRT-PCR. Our results demonstrate that microRNA detection in human skin is robust irrespective of preservation method; thus, microRNAs offer an appropriate and flexible approach in clinical practices and for diagnostic purposes in skin disorders.

Allergic contact dermatitis induces upregulation of identical microRNAs in humans and mice.

BACKGROUND: MicroRNAs are short, endogenous RNA molecules that can bind to parts of target mRNAs, thus inhibiting their translation and causing accelerated turnover or degradation of transcripts, thereby regulating gene expression. Several microRNAs have been found to be upregulated in atopic dermatitis and psoriasis, indicating a role in inflammatory skin diseases. However, there have been no studies on the expression of microRNAs in allergic contact dermatitis. OBJECTIVES: To investigate expression of microRNAs in allergic contact dermatitis. Methods. Lesional and non-lesional skin biopsies were collected from subjects with allergic responses to diphenylcyclopropenone (DPCP). Additional samples for profiling were collected from an experimental mouse model by use of the strong allergen dinitrofluorobenzene. RNA was purified from all samples, and locked nucleic acid microarray analysis was performed, followed by validation with quantitative polymerase chain reaction (PCR). RESULTS: In humans sensitized with DPCP, we found significant upregulation of miR-21, miR-142-3p, miR-142-5p and miR-223 in challenged skin. The same microRNAs were significantly upregulated in the skin of mice in a mouse model of contact allergy. The upregulation of microRNA was confirmed by quantitative PCR. CONCLUSION: These are the first results indicating that microRNAs may be involved in the pathogenesis of allergic contact dermatitis, and they show that mouse models are valuable tools for further study of the involvement of microRNAs in allergic contact dermatitis.

Inhibition of microRNA-138 enhances bone formation in multiple myeloma bone marrow niche.

Myeloma bone disease is a devastating complication of multiple myeloma (MM) and is caused by dysregulation of bone remodeling processes in the bone marrow microenvironment. Previous studies showed that microRNA-138 (miR-138) is a negative regulator of osteogenic differentiation of mesenchymal stromal cells (MSCs) and that inhibiting its function enhances bone formation in vitro. In this study, we explored the role of miR-138 in myeloma bone disease and evaluated the potential of systemically delivered locked nucleic acid (LNA)-modified anti-miR-138 oligonucleotides in suppressing myeloma bone disease. We showed that expression of miR-138 was significantly increased in MSCs from MM patients (MM-MSCs) and myeloma cells compared to those from healthy subjects. Furthermore, inhibition of miR-138 resulted in enhanced osteogenic differentiation of MM-MSCs in vitro and increased the number of endosteal osteoblastic lineage cells (OBCs) and bone formation rate in mouse models of myeloma bone disease. RNA sequencing of the OBCs identified TRPS1 and SULF2 as potential miR-138 targets that were de-repressed in anti-miR-138-treated mice. In summary, these data indicate that inhibition of miR-138 enhances bone formation in MM and that pharmacological inhibition of miR-138 could represent a new therapeutic strategy for treatment of myeloma bone disease.

miRNAs in inflammatory skin diseases and their clinical implications.

miRNAs are a class of non-coding RNA molecules that modulate gene expression post-transcriptionally. They have a major impact on several physiological and pathological cellular processes including modulation of the innate and the adaptive immune system. The role of miRNAs in skin biology is still incomplete; however, it is known that miRNAs are implicated in various cellular processes of both normal and diseased skin. Some miRNAs appear to be consistently deregulated in several different inflammatory skin diseases, including psoriasis and atopic dermatitis, indicating a common role in fundamental biological processes. The clinical implications of miRNAs are intriguing, both from a diagnostic and a therapeutic perspective. Accordingly, there is emerging evidence for the clinical potential of miRNAs as both biomarkers and possible therapeutic targets in skin diseases. Future studies will hopefully establish the biological significance of miRNAs in skin biology, paving the way for new miRNA-based diagnostic and therapeutic applications in dermatology.

MicroRNA-223 and miR-143 are important systemic biomarkers for disease activity in psoriasis.

BACKGROUND: Psoriasis is a systemic inflammatory skin disease. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules that recently have been found in the blood to be relevant as disease biomarkers. OBJECTIVE: We aimed to explore miRNAs potential as blood biomarkers for psoriasis. METHODS: Using microarray and quantitative real-time PCR we measured the global miRNA expression in whole blood, plasma and peripheral blood mononuclear cells (PBMCs) from patients with psoriasis and healthy controls. RESULTS: We identified several deregulated miRNAs in the blood from patients with psoriasis including miR-223 and miR-143 which were found to be significantly upregulated in the PBMCs from patients with psoriasis compared with healthy controls (FCH=1.63, P<0.01; FCH=2.18, P<0.01, respectively). In addition, miR-223 and miR-143 significantly correlated with the PASIscore (r=0.46, P<0.05; r=0.55, P<0.02, respectively). Receiver-operating characteristic analysis (ROC) showed that miR-223 and -143 have the potential to distinguish between psoriasis and healthy controls (miR-223: area under the curve (AUC)=0.80, miR-143: AUC=0.75). Interestingly, after 3-5 weeks of treatment with methotrexate following a significant decrease in psoriasis severity, miR-223 and miR-143 were significantly downregulated in the PBMCs from patients with psoriasis. CONCLUSION: We suggest that changes in the miR-223 and miR-143 expressions in PBMCs from patients with psoriasis may serve as novel biomarkers for disease activity in psoriasis; however, further investigations are warranted to clarify their specific roles.

MicroRNAs and potential target interactions in psoriasis.

BACKGROUND: Psoriasis is a chronic inflammatory skin disease often seen in patients with a genetic susceptibility. MicroRNAs (miRNA) are endogenous, short RNA molecules that can bind to parts of mRNA target genes, thus inhibiting their translation and causing accelerated turnover or transcript degradation. MicroRNAs are important in the pathogenesis of human diseases such as immunological disorders, as they regulate a broad range of biological processes. OBJECTIVE: We investigated miRNA-mRNA interactions in involved (PP) and non-involved (PN) psoriatic skin compared with healthy skin (NN). METHODS: Biopsies were obtained from PP, PN and NN, the miRNA and mRNA expression was analyzed by microarray techniques and a subset of miRNAs and mRNAs were validated by q-RT-PCR. Novel target interactions in psoriasis were found using PubMed, miRBase and RNAhybrid. In addition, TIMP3 protein expression was studied in PP, PN and NN. Finally, the miR-221/2-TIMP3 target interaction was studied in primary human keratinocytes by endogenous overexpression of the miRNAs. RESULTS: We identified 42 upregulated miRNAs and 5 downregulated miRNAs in PP compared with NN, and only few deregulated miRNAs in PN compared with NN. Based on the miRNA and mRNA profiles miR-21, -205, -221 and -222 were found to have the following potential mRNA targets in psoriatic skin: PDCD4, TPM1, P57, C-KIT, RTN4, SHIP2, TIMP3, RECK and NFIB. The identified target mRNAs were likely to be involved in cellular growth, proliferation, apoptosis and degradation of the extracellular matrix. Finally we found that TIMP3 is downregulated in psoriatic skin. In vitro overexpression of miR-221 and miR-222 lead to degradation of TIMP3 resulting in decreased TIMP3 protein level. CONCLUSION: Our data indicate several novel important associations for miRNAs in psoriasis and in particular the miR-221/2-TIMP3 target interaction could among others play a role in the psoriasis pathogenesis.