Recent progress in studies of miRNA and skin diseases

miRNA is a family of small non‐coding RNA that consists of 22 nucleotides on average. miRNA are implicated in various cellular activities such as cell proliferation or migration via the modulation of gene expression, and also are linked to the pathogenesis of human diseases. This paper reviews recent research progress about the contribution of miRNA to the pathogenesis of various skin diseases, and possible application of miRNA as the disease markers in each disease. For example, downregulated miR‐424‐5p in psoriatic skin causes the overexpression of MEK1 and cyclin E1 in psoriatic keratinocytes, resulting in the keratinocyte overgrowth and hyperproliferation seen in the disease. Although there was no significant difference in the serum miR‐424‐5p levels between psoriasis patients and healthy controls, serum miR‐1266‐5p levels were significantly upregulated in psoriasis patients, and showed weak and inverse correlation with disease activity. Furthermore, combination of serum levels of miR‐146a‐5p and ‐203a‐3p was more reliable to distinguish psoriasis patients and normal subjects, than each miRNA alone. Hair shaft miR‐424‐5p levels were significantly higher in psoriasis patients than normal subjects, while hair root miR‐19a‐3p levels in psoriasis patients were inversely correlated with the duration between symptom onset and the first visit to the hospital. Future researches of miRNA will enable the advances of their clinical applications including the clarification of pathogenesis, disease markers and novel treatments.     

microRNA-mediated keratinocyte hyperproliferation in psoriasis vulgaris

Background Psoriasis is a chronic inflammatory skin disease characterized by intense proliferation and abnormal differentiation of keratinocytes, although the pathogenesis is still not completely clarified. Objectives We investigated the mechanism of keratinocyte proliferation seen in psoriasis, focusing on microRNA (miRNA). Materials and methods miRNAs were extracted from tissues and sera of psoriasis, atopic dermatitis and healthy control. To determine pathogenic miRNAs, we performed miRNA polymerase chain reaction (PCR) array analysis. The results were confirmed with quantitative real‐time PCR, in situ hybridization, immunohistochemistry, transient transfection of siRNA and inhibitor in cultured keratinocytes and Western blotting. Results PCR array analysis using tissue miRNA demonstrated miR‐424 level was markedly decreased in psoriasis skin in vivo. Protein expression of mitogen‐activated protein kinase kinase 1 (MEK1) or cyclin E1, predicted target genes of miR‐424, was increased in psoriatic skin, although their mRNA levels were not. The transfection of specific inhibitor of miR‐424 in normal human keratinocytes led to upregulation of MEK1 or cyclin E1 protein, and resulted in increased cell proliferation. On the other hand, cell number was significantly decreased when cells were transfected with siRNA for MEK1 or cyclin E1. Furthermore, we first investigated serum miRNA levels in psoriasis. Although not significant, serum miR‐424 concentration tended to be decreased in patients with psoriasis compared with healthy controls. Conclusions Decreased miR‐424 expression and subsequently increased MEK1 or cyclin E1 may play a key role in the pathogenesis of psoriasis. Investigation of the regulatory mechanisms of keratinocyte proliferation by miRNA may lead to new treatments and a disease activity marker.     

Hair miR‐29a levels are decreased in patients with scleroderma

In the present study, we evaluated the possibility that we can utilize hair shaft miR‐29a levels as disease marker of scleroderma. Hair samples were obtained from 20 scleroderma patients, five dermatomyositis patients and 13 controls. microRNAs were purified from hairs as well as skins or sera, and miR‐29a levels were measured with quantitative real‐time polymerase chain reaction. Mean hair miR‐29a levels in scleroderma patients were significantly lower than those in control subjects or dermatomyositis, while expression levels of hair shaft marker keratin 34 were similar among them. There was no strong correlation among the miR‐29a levels in the hair, skin and serum of each patient, suggesting that hair microRNAs can be independent biomarkers. We found scleroderma patients with decreased miR‐29a levels had contracture of the phalanges at a significantly higher prevalence than those without. To confirm the clinical usefulness of hair microRNAs, large‐scale researches are needed in the future.     

Prevalence of interdigital psoriasis of the feet (“psoriasis alba”) in mild,moderate, and severe psoriasis

Interdigital psoriasis of the feet (“psoriasis alba”) is a rare form of inverse psoriasis. We conducted a cross‐sectional study of the prevalence of interdigital psoriasis in mild, moderate, and severe psoriasis, compared to atopic dermatitis and normal controls. Data were collected during 2010–2013 from 232 psoriatic patients, 190 patients with atopic dermatitis, and 202 normal controls. The psoriatic and atopic dermatitis patients were from the dermatology department and outpatient clinic of the Hadassah‐Hebrew University Medical Center in Jerusalem, Israel. The normal controls were healthy workers and volunteers from Hadassah Hospital who were not aware of any dermatological disease and had never consulted a general practitioner or dermatologist for skin problems of the feet. Our study revealed a prevalence of 2.6% of interdigital psoriasis of the feet in psoriatic patients, especially in men, and none in atopic dermatitis and normal controls. Three of the six affected patients with interdigital psoriasis of the feet complained of itching, both feet were involved in four patients, while two presented with additional palmoplantar psoriasis. The hematoxylin and eosin histopathological findings were in line with those found in inverse psoriasis. Dermatologists should be aware of this entity and treat it correctly. The diagnosis should be considered in psoriatic patients presenting with whitish plaque or patches in the toe‐webs, in whom the fungal test is negative and are not responding to antimycotic treatment.     

High expression levels of keratinocyte antimicrobial proteins in psoriasis compared with atopic dermatitis

Recently, it was shown that lesional skin of atopic dermatitis patients expresses low levels of some antimicrobial peptides, compared with psoriasis patients. Here we performed microarray analysis on mRNA from purified lesional epidermal cells of patients with chronic plaque psoriasis and chronic atopic dermatitis, to investigate whether this is a general phenomenon for host defense proteins, and how specific it is for this class of molecules. Microarray data were confirmed on a selected set of genes by quantitative PCR and at the protein level by immunohistochemistry. We found overexpression of many antimicrobial proteins in keratinocytes from psoriatic skin compared with atopic dermatitis skin. Interestingly, we observed that markers of normal differentiation and the activated/hyperproliferative epidermal phenotype were expressed at equal levels. Chronic lesions of psoriasis and atopic dermatitis patients are remarkably similar with respect to cellular proliferation. We conclude that psoriatic epidermis expresses high levels of host defense proteins compared with atopic dermatitis epidermis, and this phenomenon appears to be specific for these proteins. It remains to be investigated whether this is caused by genetic polymorphisms in pathways leading to an epidermal antimicrobial response, or by differences in the cellular infiltrate in psoriasis compared with atopic dermatitis.     

Scanning electron microscopy study of hair shaft disorders in psoriasis

Studies on scalp hair from psoriatic lesions have revealed marked irregularities in the cuticular pattern. The aim of this study was to investigate the incidence of hair shaft disorders in psoriatic patients and to evaluate the possibility of a correlation with scalp involvement. We examined hair from 39 psoriatic patients using scanning electron microscopy and compared it with hair from a control group of 12 healthy people. We confined our observations of the hair fibres to the areas nearest the root. Our data confirm previous observations indicating that dystrophic changes in hair cuticle cells occur more often in hairs from both unaffected and affected skin of psoriatic patients compared with normal subjects. No differences were observed between hair shafts taken from affected and unaffected psoriatic areas; cuticular breakage and an abraded cuticular surface were present only in the hair of psoriatic patients.     

Abnormal hair shafts in psoriasis on scanning electron microscopy

Summary.— We have examined hairs from psoriatic patients by scanning electron microscopy and compared them with hairs from normal subjects. Micropits were seen in normal hair cuticle cells and in those from psoriatic subjects. Their significance is unknown. Dystrophic changes of these cells are associated with the psoriatic diathesis, occurring significantly more often in hairs from unaffected as well as from affected skin of patients with psoriasis compared with controls. We confirm previous observations that the hairs growing from psoriatic plaques are significantly thinner than those growing elsewhere on psoriatic subjects and than those of normal controls. These studies confirm and expand previous evidence of hair shaft abnormalities in psoriasis.     

Phenotypic Differences between Human Blood Monocyte Subpopulations in Psoriasis and Atopic Dermatitis

Peripheral blood monocytes seem to be of importance in the initiation and maintenance of cutaneous inflammatory disorders such as psoriasis and atopic dermatitis. Functional abnormalities of monocytes have been observed in both diseases. We sought to determine whether these abnormalities are reflected by an altered phenotypic expression of functionally active surface molecules. Peripheral blood monocyte subsets varying in cellular density and cell size from patients with psoriasis and atopic dermatitis were investigated using FACS analysis employing a panel of monoclonal antibodies (CD14, CD16, HLA-DR, HLA-DQ, Fc?RII, IL-2R, ICAM-1, CR3). Furthermore, the modulation of expression by interferon-γ in monocyte subsets from patients was compared to normal controls. The results show that HLA-DR and -DQ expression on monocyte subsets in psoriatic patients was significantly decreased; “large” monocytes expressed significantly less HLA-DR than “small” monocyte subpopulations. Decreased HLA-DR and -DQ expression could be upregulated by incubation of psoriatic monocytes with IFNγ. In atopic dermatitis, a different phenotype pattern of monocyte subsets was demonstrated: HLA-DR expression and HLA-DQ expression were both decreased in both “large” and “small” monocytes as compared to normal controls. However, there were no significant differences in HLA-DR and HLA-DQ expression between “large” and “small” monocyte subpopulations in atopic dermatitis. Moreover, the ICAM-1 and IL-2R expression of “large” and “small” monocyte subpopulations was significantly decreased in atopic patients from levels in normal controls and psoriatic patients. The altered expression of HLA-DR, -DQ, ICAM-1 and IL-2R could be upregulated by incubation of atopic monocytes with IFNγ. In addition, there was a significant increase in the percentage of monocytes in the differential count of patients with psoriasis or atopic dermatitis. We conclude that the differential phenotype pattern of surface molecules on monocytes in psoriasis and atopic dermatitis may reflect an abnormal monocyte maturation/differentiation state. This may explain the functional abnormalities of monocytes observed in patients with psoriasis and atopic dermatitis.     

Are patients with psoriasis susceptible to the classic risk factors for actinic keratoses?

BACKGROUND: An increased prevalence of benign solar damage (eg, facial wrinkles) but not neoplastic lesions was observed among patients with psoriasis who were exposed to Dead Sea climatotherapy compared with controls. OBJECTIVES: To compare the prevalence of actinic keratosis in psoriatic patients and controls and to assess whether known risk factors behave similarly in both groups. DESIGN: Multicenter cross-sectional study. SETTING: Dermatology clinics in 4 participating Israeli hospitals and at a Dead Sea clinic. PARTICIPANTS: Adult subjects (n = 460) with plaque-type psoriasis were recruited from the Israel Psoriasis Association (volunteer sample) and from dermatology clinics (convenience sample). The control group (n = 738) consisted of nonimmunosuppressed patients attending these clinics for benign conditions unrelated to sun exposure, such as atopic or contact dermatitis. MAIN OUTCOME MEASURES: Prevalence and distribution of actinic keratoses and odds ratios associated with skin, hair, and eye color and propensity or history of sunburn adjusted for age, ethnicity, and sun exposure. RESULTS: Actinic keratoses were observed in 200 controls (27%) and 51 subjects (11%) (P<.001). This increased prevalence occurred in both sexes, participants aged 35 years or older, all ethnic groups, smokers, and nonsmokers. The anatomical distribution of lesions did not substantially differ between subjects and controls. In multivariate analysis, psoriasis conferred a protective effect (odds ratio, <1), as did dark skin, dark eyes, and a history of severe sunburn in childhood. However, significant interactions were observed between psoriasis and hair color as well as psoriasis and propensity to sunburn, whereby a linear association was observed for controls but not for patients with psoriasis. CONCLUSIONS: Psoriasis confers protection against actinic keratosis. Hair color and propensity to sunburn exert differential effects among psoriatic patients and controls.     

The mesenchymal stem cell profile in psoriasis

Background The expression of inducible nitric oxide synthase (iNOS) and vascular endothelial growth factor (VEGF) and the level of total oxyradical scavenging capacity have been evaluated extensively in the cutaneous cells of patients with psoriasis. As yet, no indications are available about the undifferentiated cells, the mesenchymal stem cells (MSCs), isolated from skin. Objectives To isolate MSCs in patients with psoriasis and to compare them with those obtained from atopic and healthy subjects, in order to analyse whether MSCs show some typical psoriatic profiles and to understand whether pathophysiological events leading to psoriasis start early at the stem cell level. Methods MSCs isolated from seven patients with psoriasis, seven patients with acute atopic dermatitis and seven healthy subjects were characterized by fluorescence‐activated cell sorting analysis. VEGF and nitric oxide (NO) content was measured in conditioned medium, the expression of VEGF and iNOS was analysed by immunohistochemistry, and the total oxyradical scavenging capacity towards peroxynitrite was tested. Results VEGF content was highest in the medium conditioned by psoriatic perilesional MSCs, whereas NO concentration was maximally increased in medium conditioned by MSCs isolated from lesional psoriatic skin. The ability to neutralize the oxidizing effects of peroxynitrite was lower for MSCs isolated from lesional psoriatic skin compared with other MSCs, except for MSCs of lesional atopic skin. Conclusions The microenvironment in psoriasis differs from those of atopic dermatitis and healthy skin; it could induce resident MSCs to produce angiogenic and proinflammatory mediators which lead to a reduction in the antioxidant capacity of these cells, contributing to the development of skin lesions in psoriasis.     

Very late antigen-1 in psoriasis: an immunohistochemical study

Background Currently, psoriasis is thought to be an inflammatory response to an antigenic stimulation, in which angiogenesis plays a fundamental role. Very late antigen‐1 (VLA‐1) is a β₁ integrin collagen receptor that is up‐regulated in many angiogenic processes. Data on its role in psoriasis are sparse. Objective In a prospective study, we evaluated the staining of VLA‐1 in lesional skin from patients with psoriasis and atopic dermatitis. Material and methods Frozen sections from skin biopsies of patients with chronic plaque‐type psoriasis (n = 18) and chronic atopic dermatitis (n = 7) were stained with a monoclonal antibody to VLA‐1. The number of blood vessels stained with VLA‐1 and the staining intensity were evaluated. These were correlated with the histologic features. Results The absolute number of blood vessels was found to be similar in the atopic and psoriatic samples. However, the number of vessels stained with anti‐VLA‐1, as well as the staining intensity, was shown to be significantly higher in the psoriasis group (P < 0.05). Differences between psoriatic lesions showing typical histological features of psoriasis and those showing features that overlap with dermatitis were found as well. Conclusions Expression of VLA‐1 was found significantly higher in lesional dermal blood vessels of psoriatic patients compared with atopic patients. These findings suggest a possible role for VLA‐1 in the pathological angiogenesis of psoriasis. It may be an additional tool for establishing the diagnosis of psoriasis and provide a basis for new strategies in the treatment of psoriasis.     

Expression of CCL1 and CCL18 in atopic dermatitis and psoriasis

Background.  Recent studies have shown that chemoattractive proteins play an important role in the organization of the innate and adaptive immune responses. There are some reports that chemokine (C‐C motif) ligand (CCL)1 and CCL18, members of a family of chemoattractive proteins, have increased expression in atopic dermatitis (AD). Aim.  To evaluate the quantity and pattern of CCL1 and CCL18 expression in lesions and blood of patients with AD, and compare them with those of patients with psoriasis. Methods.  Biopsy specimens were taken from atopic skin and normal‐appearing skin of patients with AD and from the psoriatic skin only of patients with psoriasis. Quantitative real‐time PCR analysis and immunohistochemistry of CCL1 and CCL18 expression were performed, and the quantities of expressed CCL1 and CCL18 in acute AD were compared with those of normal‐appearing atopic skin and psoriatic skin. The serum level of CCL1 and CCL18 was assessed by ELISA. Results.  Expression of CCL1 mRNA and protein was significantly higher in the acute lesional skin of patients with AD than in their nonlesional skin or in the lesional skin of patients with psoriasis. Both CCL18 mRNA and protein were abundant in acute AD lesions and in psoriatic lesions, but were lower in the nonlesional skin of patients with AD. The serum levels of CCL1 and CCL18 were not different in patients with AD and patients with psoriasis. Conclusions.  CCL1 is a chemokine that is associated with AD. Both CCL1 and CCL18 may play important roles in the initiation and progression of atopic skin inflammation.     

Hair shaft abnormalities--clues to diagnosis and treatment

Hair dysplasias are congenital or acquired alterations which often involve the hair shaft. Hair shaft abnormalities are characterized by changes in color, density, length and structure. Hair shaft alterations often result from structural changes within the hair fibers and cuticles which may lead to brittle and uncombable hair. The hair of patients with hair shaft diseases feels dry and looks lusterless. Hair shaft diseases may occur as localized or generalized disorders. Genetic predisposition or exogenous factors produce and maintain hair shaft abnormalities. Hair shaft diseases are separated into those with and those without increased hair fragility. In general, optic microscopy and polarized light microscopy of hair shafts provide important clues to the diagnosis of isolated hair shaft abnormalities or complex syndromes. To establish an exact diagnosis of dysplastic hair shafts, a structured history and physical examination of the whole patient are needed which emphasizes other skin appendages such as the nails, sweat and sebaceous glands. Profound knowledge on hair biology and embryology is necessary to understand the different symptom complexes. Therapy of hair shaft disorders should focus on the cause. In addition, minimizing traumatic influences to hair shafts, such as drying hair with an electric dryer or permanent waves and dyes, is important. A short hairstyle is more suitable for patients with hair shaft disorders.     

Increased concentration of beta-endorphin in sera of patients with psoriasis and other inflammatory dermatoses

Serum beta-endorphin was quantified by radioimmunoassay in 71 patients with psoriasis vulgaris, other chronic inflammatory skin diseases with T-cell infiltrates [atopic dermatitis (n=25), and systemic sclerosis (n=34)], and 100 healthy subjects. The neuropeptide was found to be markedly (P<0.001) increased in patients with psoriasis (14.4 pg/ml), atopic dermatitis (9.2 pg/ml) and systemic sclerosis (9.8 pg/ml) compared with normal controls (6.1 pg/ml). The highest values of β-endorphin were found in patients with actively spreading plaque psoriasis (17.3 pg/ml), whereas lesion-free patients showed a reduction in neuropeptide concentration (10.2 pg/ml), The levels were much higher in patients with widespread psoriatic lesions (>60% body surface; 16.2 pg/ml), which lasted longer than 3 months (15.8 pg/ml), whereas neither the presence of stress nor itching correlated with the serum peptide concentration. Our data suggest that β-endorphin is produced in psoriatic lesions by inflammatory cells, rather than the increased levels being the result of activation of the pituitary-adrenal axis by chronic stress. The generation of neuropeptide in psoriatic lesions and its antinociceptive effect on the peripheral sensory nerves might explain why pruritus is a relatively rare phenomenon in psoriasis.     

Exacerbation of atopic dermatitis symptoms by ustekinumab in psoriatic patients with elevated serum immunoglobulin E levels: Report of two cases

Psoriasis is a chronic inflammatory skin disease mainly mediated by a T‐helper cell subset, Th17 cells. Recently, increased levels of total serum immunoglobulin (Ig)E have been reported in a subset of psoriatic patients. Ustekinumab (UST) is one of the most commonly used biologic agents for the treatment of moderate to severe plaque psoriasis, and a previous report also documented effectiveness of UST for psoriatic patients with high serum IgE levels. We experienced two psoriatic patients with high serum IgE levels, in whom UST completely improved psoriasis but paradoxically provoked or exacerbated atopic dermatitis (AD)‐like symptoms. This reciprocal phenomenon suggests the shift of Th balance toward Th2, along with altered profiles of inflammatory cytokines. It appears prudent to consider the possibility of such adverse effects when treating psoriatic patients with UST with concomitant AD symptoms, a history of AD or high serum IgE levels.     

Cellular reactivity of polymorphonuclear leukocytes in psoriasis and atopic dermatitis--measurement of lucigenin-dependent chemiluminescence

Polymorphonuclear leukocytes (PMN) of patients suffering from psoriasis and atopic dermatitis are supposed to differ in their function from the PMN of normals. However, conflicting results have been reported. Using a lucigenin-dependent chemiluminescence we investigated the response of isolated PMN from patients with atopic dermatitis (AD) and psoriasis to different stimuli. PMN of 17 patients with psoriasis and 13 patients with AD with mild to moderate disease activity were stimulated with a chemotactic peptide (f-met-phe), zymosan activated serum (ZAS), zymosan particles and phorbol myristate acetate. In the AD group we found a significantly decreased response after stimulation with ZAS in comparison to the controls. With the other stimuli tested no significant difference was detected. In comparison to normal controls psoriatic PMN showed no significant difference with any of the stimuli. Comparing patients with plaque-type and guttate-type psoriasis no significant difference was detected. We suggest that the reported hyperactivation of psoriatic PMN could be triggered by serum factors which were excluded in the present investigation. The decreased response of PMN to stimulation with ZAS from patients with AD associated with a normal reactivity to the other stimuli could be due to specific desensitization of the PMN by C5a in vivo.     

Hair shaft miRNA‐221 levels as a new tumor marker of malignant melanoma

miRNA‐221 (miR‐221) is known to be abnormally expressed in many human cancers. The serum levels of miR‐221 have been reported as a tumor marker for malignant melanoma (MM). We hypothesized that the hair shaft miR‐221 levels may be increased in patients with MM. We therefore assessed the possibility that hair shaft miR‐221 levels could be a marker for MM. The hair shaft miR‐221 levels were significantly higher in patients with MM than controls. The rates of increased hair shaft miR‐221 levels above the cut‐off value were comparable to those of serum 5‐S‐CD, which is a tumor marker commonly used for MM. Measurements of the hair shaft miR‐221 levels could have potential clinical value in the detection of MM. This is the first report investigating the hair shaft levels of an miRNA in patients with MM. Our investigations offer new insight into the relationship between miR‐221 and MM, and may provide a new, non‐invasive way to screen for melanoma.     

Surfactant protein D in atopic dermatitis and psoriasis

The collectin surfactant protein-D (SP-D) shows antimicrobial and immuno-regulatory properties and has recently been detected in the basal layers of normal human skin. This molecule potentially plays an important role in inflammatory skin diseases and therefore SP-D content and location was examined using immunohistochemistry on skin biopsies from patients with the two major dermatologic diseases, psoriasis and atopic dermatitis. SP-D was located in the stratum basale of all biopsies with similar intense staining in both diseased and normal skin. Differences were detected in stratum spinosum where involved psoriatic skin showed intense staining through the entire region significantly different from uninvolved and normal skin. Lesional atopic skin showed moderate staining extending through the basal three-fourths of stratum spinosum. Using real time polymerase chain reaction analysis, no substantial up-regulation of SP-D mRNA was detected in lesional psoriatic skin, and a comparison of serum levels of SP-D between patients with atopic dermatitis or psoriasis and a group of age matched healthy controls did not show significant differences. In conclusion SP-D was significantly more abundant in the stratum spinosum of lesional psoriatic and atopic skin due to more cells producing the molecule rather than up-regulation of production in single cells of diseased skin. Further studies are needed to show if SP-D plays a role in the protection against skin infections or modulation of the inflammatory process in these common skin diseases.