Identifying targets for topical RNAi therapeutics in psoriasis: assessment of a new in vitro psoriasis model

Advances in psoriasis research: From pathogenesis to therapeutics

Psoriasis is a chronic inflammatory condition affecting approximately 2 % to 3 % of the global population. The pathogenesis of psoriasis is complex, involving immune dysregulation, hyperproliferation and angiogenesis. It is a multifactorial disease which is influenced by genetic and environmental factors. The development of various therapeutic agents, such as JAK inhibitors, small molecules, and biologics with potential anti-psoriatic properties was possible with the vast understanding of the pathogenesis of psoriasis. Various signalling pathways, including NF-κB, JAK-STAT, S1P, PDE-4, and A3AR that are involved in the pathogenesis of psoriasis as well as the preclinical models utilised in the research of psoriasis have been highlighted in this review. The review also focuses on technological advancements that have contributed to a better understanding of psoriasis. Then, the molecules targeting the respective signalling pathways that are still under clinical trials or recently approved as well as the latest breakthroughs in therapeutic and drug delivery approaches that can contribute to the improvement in the management of psoriasis are highlighted in this review. This review provides an extensive understanding of the current state of research in psoriasis, giving rise to opportunities for researchers to discover future therapeutic breakthroughs and personalised interventions. Efficient treatment options for individuals with psoriasis can be achieved by an extensive understanding of pathogenesis, therapeutic agents, and novel drug delivery strategies.

Emerging roles of non-coding RNAs in psoriasis pathogenesis

Psoriasis is a complex genetic skin disorder typically manifested by red, scaly, and itchy plaques most commonly over the scalp, trunk, elbows, and knees. Histopathological features include thickening of the epidermal layer due to hyper-proliferation and abnormal differentiation of epidermal keratinocytes along with infiltration of immune cells in the psoriatic skin. It is a chronic inflammatory relapsing disease, and there is currently no permanent cure for psoriasis. Proper medications can reduce the severity of the disease and improve the quality of life of the patients. While the genetic components of psoriasis pathogenesis are well explored, the full understanding of its epigenetic component remains elusive. Non-coding RNAs (ncRNAs) are documented to regulate various epigenetic processes that lead to the pathogenesis of different diseases including psoriasis. In this review, we have discussed the molecular interplay of different ncRNAs in psoriasis pathogenesis. The roles of microRNAs (miRNAs) in psoriasis are pretty well studied, whereas the roles of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) are emerging. This review provides ideas covering some of the latest findings of different modes of functions played by those different ncRNAs documented in the literature. As an ever-evolving topic, some works are still ongoing as well as there are several fields that need rigorous scientific ventures. We have proposed the areas which claim more explorations to better understand the roles played by the ncRNAs in psoriasis pathogenesis.

Evaluation of the Efficacy of Xyloglucan, Pea Protein and Opuntia ficus-indica Extract in a Preclinical Model of Psoriasis

Psoriasis is a chronic inflammatory skin disease characterized by epidermal gene abnormalities, epidermal barrier defects and inflammation. Corticosteroids are considered to be standard treatments, but often come with side effects and lose efficacy with long-term use. Alternative treatments targeting the epidermal barrier defect are needed to manage the disease. Film-forming substances such as xyloglucan, pea protein and Opuntia ficus-indica extract (XPO) have generated interest for their ability to restore skin barrier integrity and may pose an alternative approach to disease management. Thus, the aim of this two-part study was to evaluate the barrier-protective properties of a topical cream containing XPO on the membrane permeability of keratinocytes exposed to inflammatory conditions and compare its efficacy to dexamethasone (DXM) in an in vivo model of psoriasis-like dermatitis. XPO treatment significantly reduced S. aureus adhesion, subsequent skin invasion and restored epithelial barrier function in keratinocytes. Furthermore, the treatment restored the integrity of keratinocytes, reducing tissue damage. In mice with psoriasis-like dermatitis, XPO significantly reduced erythema, inflammatory markers and epidermal thickening with a superior efficacy to dexamethasone. Given the promising results, XPO may represent a novel steroid-sparing therapeutic for epidermal-related diseases such as psoriasis, thanks to its ability to preserve skin barrier function and integrity.

miRNA-203b-3p Induces Acute and Chronic Pruritus through 5-HTR2B and TRPV4

Growing evidence indicates that transient receptor potential (TRP) channels contribute to different forms of pruritus. However, the endogenous mediators that cause itch through transient receptor potential channels signaling are poorly understood. In this study, we show that genetic deletion or pharmacological antagonism of TRPV4 attenuated itch in a mouse model of psoriasis induced by topical application of imiquimod. Human psoriatic lesions showed increased expression of several microRNAs, including the miR-203b-3p, which induced a calcium ion response in rodent dorsal root ganglion neurons and scratching behavior in mice through 5-HTR2B activation and the protein kinase C‒dependent phosphorylation of TRPV4. Computer simulation revealed that the miR-203b-3p core sequence (GUUAAGAA) that causes 5-HTR2B/TRPV4-dependent itch targets the extracellular side of 5-HTR2B by interacting with a portion of the receptor pocket consistent with its activation. Overall, we reveal the unconventional pathophysiological role of an extracellular microRNA that can behave as an itch promoter through 5-HTR2B and TRPV4.

Effect of Melatonin on Psoriatic Phenotype in Human Reconstructed Skin Model

Psoriasis is an inflammatory and auto-immune skin-disease characterized by uncontrolled keratinocyte proliferation. Its pathogenesis is not still fully understood; however, an aberrant and excessive inflammatory and immune response can contribute to its progression. Recently, more attention has been given to the anti-inflammatory and immunomodulators effects of melatonin in inflammatory diseases. The aim of this paper was to investigate the effect of melatonin on psoriatic phenotype and also in S. aureus infection-associated psoriasis, with an in vitro model using Skinethic Reconstructed Human Epidermis (RHE). An in vitro model was constructed using the RHE, a three-dimensional-model obtained from human primary-keratinocytes. RHE-cells were exposed to a mix of pro-inflammatory cytokines, to induce a psoriatic phenotype; cells were also infected with S. aureus to aggravate psoriasis disease, and then were treated with melatonin at the concentrations of 1 nM, 10 nM, and 50 nM. Our results demonstrated that melatonin at higher concentrations significantly reduced histological damage, compared to the cytokine and S. aureus groups. Additionally, the treatment with melatonin restored tight-junction expression and reduced pro-inflammatory cytokine levels, such as interleukin-1β and interleukin-12. Our results suggest that melatonin could be considered a promising strategy for psoriasis-like skin inflammation, as well as complications of psoriasis, such as S. aureus infection.

Development of a 3D psoriatic skin model optimized for infiltration of IL-17A producing T cells: Focus on the crosstalk between T cells and psoriatic keratinocytes

Psoriasis is a chronic inflammatory skin disease involving several cell types, including T cells, via the IL-23/IL-17 axis. IL-17A acts on the surrounding epithelial cells thus resulting in an inflammatory feedback loop. The development of immunocompetent models that correctly recapitulate the complex phenotype of psoriasis remains challenging, which also includes both the T cell isolation and activation methods. The purpose of this work was to develop an advanced in vitro 3D psoriatic skin model that enables the study of the impact of T cells on psoriatic epithelial cells. To reach that aim, healthy and psoriatic fibroblasts and keratinocytes were used to reproduce this tissue-engineered skin model in which activated T cells, isolated beforehand from human whole blood, have been incorporated. Our study showed that isolation of T cells with the EasySep procedure, followed by activation with PMA/ionomycin, mimicked the psoriatic characteristics in an optimal manner with the production of inflammatory cytokines important in the pathogenesis of psoriasis, as well as increased expression of Ki67, S100A7, elafin and involucrin. This psoriatic model enriched in activated T cells displayed enhanced production of IL-17A, IFN-ƴ, CCL2, CXCL10, IL-1ra, IL-6 and CXCL8 compared with the healthy model and whose increased secretion was maintained over time. In addition, anti-IL17A treatment restored some psoriatic features, including epidermal thickness and basal keratinocytes proliferation, as well as a downregulation of S100A7, elafin and involucrin expression. Altogether, our study demonstrated that this model reflects a proper psoriatic inflammatory environment and is effective for the investigation of epidermal and T cell interaction over time. STATEMENT OF SIGNIFICANCE: The aim of this study was to provide an innovative 3D immunocompetent human psoriatic skin model. To our knowledge, this is the first immunocompetent model that uses skin cells from psoriatic patients to study the impact of IL-17A on pathological cells. Through the use of this model, we demonstrated that the T-cell enriched psoriatic model differs from T-cell enriched healthy model, highlighting efficient crosstalk between pathologic epithelial cells and T cells. This advanced preclinical model further mimics the original psoriatic skin and will prove relevant in predicting clinical outcomes, thereby decreasing inaccurate predictions of compound effects.

TNFα siRNA delivery by nanoparticles and photochemical internalization for psoriasis topical therapy

Psoriasis is a chronic inflammatory skin disease that presents increased expression of tumor necrosis factor α (TNFα), a proinflammatory cytokine. The discovery of RNA interference (RNAi), mediated by short interfering RNA (siRNA), made it possible for the expression of some genes to be eliminated. However, for its application, it is necessary to use carriers that can protect siRNA and release it in the target cells. Herein, we developed a delivery system for siRNA based on hybrid polymer-lipid nanoparticles (PLNs) and combined this system with photochemical internalization (PCI), photoactivating the photosensitizer TPPS2a, to optimize the endosomal escape of TNFα siRNA in the cytoplasm, aiming to use the system as a topical formulation to treat psoriasis. The PLNs composed of 2.0% of Compritol® 888 ATO (lipid), 1.5% of poloxamer 188 and 0.1% of the cationic polymer poly(allylamine hydrochloride) showed an average nanoparticle size of 142 nm, a zeta potential of +25 mV, and the ability to efficiently coencapsulate TPPS2a and complexed siRNA. In addition, these materials did not present cellular toxicity and showed high cellular uptake. In vitro delivery studies using porcine skin model revealed that the PLNs delivered siRNA and TPPS2a into the skin. The efficacy was verified using an in vivo psoriasis animal (hairless mouse) model induced by imiquimod (IMQ) cream. The results revealed that PLN-TPPS2a-TNFα siRNA combined with PCI resulted in a decrease in the levels of TNFα, showing the efficiency of the treatment to silence this cytokine in psoriatic lesions, which was accompanied by a reduction in the redness and scaling of the mouse skin. The results showed the potential of the developed PLNs in combined silencing gene therapy and PCI for topical treatment of psoriasis.

Anti-Inflammatory and Pro-Differentiating Properties of the Aryl Hydrocarbon Receptor Ligands NPD-0614-13 and NPD-0614-24: Potential Therapeutic Benefits in Psoriasis

The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor expressed in all skin cell types, plays a key role in physiological and pathological processes. Several studies have shown that this receptor is involved in the prevention of inflammatory skin diseases, e.g., psoriasis, atopic dermatitis, representing a potential therapeutic target. We tested the safety profile and the biological activity of NPD-0614-13 and NPD-0614-24, two new synthetic AhR ligands structurally related to the natural agonist FICZ, known to be effective in psoriasis. NPD-0614-13 and NPD-0614-24 did not alter per se the physiological functions of the different skin cell populations involved in the pathogenesis of inflammatory skin diseases. In human primary keratinocytes stimulated with tumor necrosis factor-α or lipopolysaccharide the compounds were able to counteract the altered proliferation and to dampen inflammatory signaling by reducing the activation of p38MAPK, c-Jun, NF-kBp65, and the release of cytokines. Furthermore, the molecules were tested for their beneficial effects in human epidermal and full-thickness reconstituted skin models of psoriasis. NPD-0614-13 and NPD-0614-24 recovered the psoriasis skin phenotype exerting pro-differentiating activity and reducing the expression of pro-inflammatory cytokines and antimicrobial peptides. These data provide a rationale for considering NPD-0614-13 and NPD-0614-24 in the management of psoriasis.

Small interfering RNA targeting of keratin 17 reduces inflammation in imiquimod-induced psoriasis-like dermatitis

Background

Psoriasis is a common chronic inflammatory skin disease with 2% to 3% prevalence worldwide and a heavy social-psychological burden for patients and their families. As the exact pathogenesis of psoriasis is still unknown, the current treatment is far from satisfactory. Thus, there is an urgent need to find a more effective therapy for this disease. Keratin 17 (K17), a type I intermediate filament, is overexpressed in the psoriatic epidermis and plays a critical pathogenic role by stimulating T cells in psoriasis. Therefore, we hypothesized that inhibiting K17 may be a potential therapeutic approach for psoriasis. This study aimed to investigate the therapeutic effect of K17-specific small interfering RNA (siRNA) on mice with imiquimod (IMQ)-induced psoriasis-like dermatitis.

Methods

Eight-week-old female BALB/c mice were administered a 5% IMQ cream on both ears to produce psoriatic dermatitis. On day 3, K17 siRNA was mixed with an emulsion matrix and applied topically to the left ears of the mice after IMQ application every day for 7 days. The right ears of the mice were treated in parallel with negative control (NC) siRNA. Inflammation was evaluated by gross ear thickness, histopathology, the infiltration of inflammatory cells (CD3⁺ T cells and neutrophils) using immunofluorescence, and the expression of cytokine production using real-time quantitative polymerase chain reaction. The obtained data were statistically evaluated by unpaired t-tests and a one-way analysis of variance.

Results

The severity of IMQ-induced dermatitis on K17 siRNA-treated mice ears was significantly lower than that on NC siRNA-treated mice ears, as evidenced by the alleviated ear inflammation phenotype, including decreased ear thickness, infiltration of inflammatory cells (CD3⁺ T cells and neutrophils), and inflammatory cytokine/chemokine expression levels (interleukin 17 [IL-17], IL-22, IL-23, C-X-C motif chemokine ligand 1, and C-C motif chemokine ligand 20) (P < 0.05 vs. the Blank or NC siRNA groups). Compared to the NC siRNA treatment, the K17 siRNA treatment resulted in increased K1 and K10 expression, which are characteristic of keratinocyte differentiation (vs. NC siRNA, K17 siRNA1 group: K1, t = 4.782, P = 0.0050; K10, t = 3.365, P = 0.0120; K17 siRNA2 group: K1, t = 4.104, P = 0.0093; K10, t = 4.168, P = 0.0042; siRNA Mix group: K1, t = 3.065, P = 0.0221; K10, t = 10.83, P < 0.0001), and decreased K16 expression, which is characteristic of keratinocyte proliferation (vs. NC siRNA, K17 siRNA1 group: t = 4.156, P = 0.0043; K17 siRNA2 group: t = 2.834, P = 0.0253; siRNA Mix group: t = 2.734, P = 0.0250).

Conclusions

Inhibition of K17 expression by its specific siRNA significantly alleviated inflammation in mice with IMQ-induced psoriasis-like dermatitis. Thus, gene therapy targeting K17 may be a potential treatment approach for psoriasis.

Spherical Gold Nanoparticles: Small Interfering RNA Delivery in Regulation of the Tumor Necrosis Factor-Alpha Gene Expression

Proinflammatory cytokines are signaling molecules that are expelled from immune cells like macrophages and other types of cells. Tumor necrosis factor-alpha (TNF-α) is overexpressed during inflammation caused by inflammatory diseases. Therefore, the regulation of TNF-α has a key role in inflammation. The use and target delivery of small interfering RNAs (siRNAs) provide many effectual treatment benefits in the regulation of gene expression in cells. In this study, we used siRNA nanoparticle conjugates in the regulation of gene expression and inflammation. We first prepared safe fusion ribonucleic acid interference carrier, spherical nucleic acid nanoparticle conjugates (SNA-NCs), to enhance the perforation of siRNA into the macrophages and their ability to target TNF-α gene regulation. Furthermore, the suppression of the TNF-α gene was monitored after curing macrophages by SNA-NCs. Gene expression was carried out by real-time polymerase chain reaction in cells and the levels of TNF-α were investigated by the enzyme-linked immunosorbent assay (ELISA) method. This study indicated that the SNA-NCs were safe and very stable. TNF-α siRNA could significantly regulate gene expression in cells to form SNA-NCs. The results indicated that TNF-α gene expression downregulated to 93.40% ± 1.45%, 66.06% ± 0.95%, and 35.76% ± 1.09% in the presence of 0.1, 1, and 10 nM siRNA, respectively. The proliferation of macrophages and subsequently expression of TNF-α were significant for the formation of inflammation. These findings showed that the use of SNA-NC siRNA might ameliorate the inflammatory disease by suppression of gene expression and functional activity of macrophage generation.

Pathogenesis of psoriasis in the "omic" era. Part II. Genetic, genomic and epigenetic changes in psoriasis

Psoriasis is a multifactorial disease in which genetic, environmental and epigenetic factors regulating gene expression play a key role. In the “genomic era”, genome-wide association studies together with target genotyping platforms performed in different ethnic populations have found more than 50 genetic susceptible markers associated with the risk of psoriasis which have been identified so far. Up till now, the strongest association with the risk of the disease has been proved for HLA-C*06 gene. The majority of other psoriasis risk SNPs are situated near the genes encoding molecules involved in adaptive and innate immunity, and skin barrier function. Many contemporary studies indicate that the epigenetic changes: histone modification, promoter methylations, long non-coding and micro-RNA hyperexpression are considered as factors contributing to psoriasis pathogenesis as they regulate abnormal keratinocyte differentiation and proliferation, aberrant keratinocytes – inflammatory cells communication, neoangiogenesis and chronic inflammation. The circulating miRNAs detected in the blood may become specific markers in the diagnosis, prognosis and response to the treatment of the disease. The inhibition of expression in selected miRNAs may be a new promising therapy option for patients with psoriasis.

Effect of RNA Interference Targeting STAT3 Gene Combined with Ultrasonic Irradiation and SonoVue Microbubbles on Proliferation and Apoptosis in Keratinocytes of Psoriatic Lesions

Background

Signal transducer and activator of transcription 3 (STAT3) was strongly expressed and activated in psoriatic keratinocytes (KCs) and correlated with the severity of psoriasis. The study aimed to investigate the effects of STAT3 small interfering RNA (siRNA) combined with ultrasonic irradiation and SonoVue microbubbles on the proliferation and apoptosis in KCs of psoriatic lesions and the relative mechanisms.

Methods

Psoriatic KCs were transfected under four experimental conditions: (1) STAT3 siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group); (2) STAT3 siRNA only carried by Lipofectamine 3000 (L group); (3) the negative control of siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (siRNA-NC); (4) not treated as Blank. Cell Counting Kit-8 assay was used to evaluate the cell proliferation. Cell cycle analysis was detected with cycle test Plus DNA reagent kit associated with flow cytometer. FITC Annexin V apoptosis detection kit associated with flow cytometer was applied for apoptosis analysis. Fluo calcium indicator associated with flow cytometer was used to analyze intracellular free calcium concentration ([Ca²⁺]_i). The expressions of cyclin D1 and Bcl-xL were detected both at the mRNA level by real-time reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. The obtained data were statistically evaluated by two-way analysis of variance.

Results

STAT3 siRNA inhibited the growth of KCs in a time-dependent manner showing the highest proliferation inhibition in LUS group with proliferation ratio of 45.38% ± 5.85% at 72h (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced an altered cell cycle distribution of KCs showing the highest increases in G2/M-phase population up to 18.06% ± 0.36% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced late apoptosis of KCs with the highest late apoptosis percentage of 22.87% ± 1.28% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the elevation of [Ca²⁺]_iof KCs with the highest calcium fluorescence intensity mean of 1213.67 ± 60.51 in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the downregulation of cyclin D1 and Bcl-xL expressions of KCs at mRNA and protein levels with the lowest expressions in LUS group with cyclin D1 expression of 51.81% ± 9.58% and 70.17% ± 4.22% at mRNA level and at protein level, respectively, and with Bcl-xL expression of 37.58% ± 4.92% and 64.06% ± 7.78% at mRNA level and at protein level, respectively (P < 0.05 vs. L group, siRNA-NC, or Blank).

Conclusions

STAT3 siRNA inhibited the growth and induced the apoptosis in psoriatic KCs likely partly through altering cell cycle distribution, elevating [Ca²⁺]_i, and downregulating cyclin D1 and Bcl-xL expressions. Silencing the target gene STAT3 in psoriatic KCs with siRNA combined with ultrasonic irradiation and microbubbles would contribute to a significant innovation as a new clinical therapy for psoriasis.

Rapamycin ameliorates psoriasis by regulating the expression and methylation levels of tropomyosin via ERK1/2 and mTOR pathways in vitro and in vivo

Psoriasis is a chronic inflammatory disease, affecting more than millions of people in the world. Recently, the mTOR inhibitor rapamycin (RAPA) was reported to be involved in the pathogenesis of psoriasis. However, the underlying mechanism remains unclear. Haematoxylin and eosin staining was used to examine the effects of RAPA on inflammatory level of lesional tissues from patients with psoriasis and animal models. Quantitative real-time PCR, immunohistochemistry and western blot assay were performed to assess the effects of RAPA on tropomyosins (TPMs) expression in patients with psoriasis, cell models and animal models. Phalloidin staining was used to assess the RAPA effects on cell skeleton. The effects of RAPA on cell proliferation and cell cycle were detected by CCK-8 assay, EdU staining and flow cytometry. Methylation status of TPMs was analysed by methylation-specific PCR. The expression of TPM1 and TPM2 was significantly downregulated, while their methylation level was obviously higher in the lesional tissues, cell models and animal models of psoriasis. After treated with RAPA, the expression and methylation levels of TPMs were all restored in the cell models and animal models of psoriasis. RAPA inhibited cell proliferation and decreased the ratio of S phase cell in Hacat or human epidermal keratinocytes cell models of psoriasis. Finally, the activated ERK1/2 and mTOR pathways in the cell model and animal model of psoriasis were suppressed by the treatment of RAPA. RAPA could be used as an effective agent for the treatment of psoriasis by decreasing the methylation level of TPM1 and TPM2 via inhibiting the ERK1/2 and mTOR signalling pathways.

Molecular action of isoflavone genistein in the human epithelial cell line HaCaT

Due to its strong proliferation-reducing effects on keratinocytes, and also anti-inflammatory properties, the isoflavone genistein has already been proposed as a possible antipsoriatic compound. As there is still no detailed information on this topic, we examined the effects of genistein by using an in vitro model of both, normal and "psoriasis-like" keratinocytes at this stage of our work exhaustively testing the selected flavonoid in a mono-treated experimental design. Gene expression studies revealed transcriptional changes that confirms known disease-associated pathways and highlights many psoriasis-related genes. Our results suggested that aberrant expression of genes contributing to the progress of psoriasis could be improved by the action of genistein. Genistein prevented "cytokine mix" as well as TNF-α-induced NF-κB nuclear translocation, with no effect on the PI3K signaling cascade, indicating the luck of turning this pathway into NF-κB activation. It could have attenuated TNF-α and LPS-induced inflammatory responses by suppressing ROS activation. Regardless of the type of keratinocyte stimulation used, reduction of cytokine IL-8, IL-20 and CCL2 production (both at RNA and protein level) following genistein treatment was visible. Because investigations of other groups supported our commentary on potential administration of genistein as a potential weapon in the armamentarium against psoriasis, it is believed that this paper should serve to encourage researchers to conduct further studies on this subject.

Role of an imbalanced miRNAs axis in pathogenesis of psoriasis: novel perspectives based on review of the literature

BACKGROUND

Specific profile of microRNAs (miRNAs, miR) expressed in psoriasis has been identified in the past few years, while the studies on roles and molecular mechanisms of these miRNAs are still on the way. In our previous study, four specific miRNAs (miR-31, miR-203, hsa-miR-99a and miR-125b) were found to be specifically altered in psoriatic lesions.We therefore conducted a systematic literature review in this study to reveal the role of these miRNAs in the pathogenesis of psoriasis in order to inform future research.

METHODS

The related articles indexed in PubMed (MEDLINE) database were searched and analyzed. We identified eligible studies related to the mechanism research of miR-31, miR-203, hsa-miR-99a and miR-125b in psoriasis or psoriatic lesional skin from inception up to July 2016. The experts in the field of miRNAs and Psoriasis were involved in analysis process.

RESULT

Both miR-31 and miR-203 are dramatically upregulated in psoriatic lesions. The former plays the pro-proliferative, pro-differentiative and pro-inflammatory roles and the latter holds the potentials for anti-proliferation, pro-inflammation and pro-differentiation in psoriatic keratinocytes. Conversely, both hsa-miR-99a and miR-125b are significantly downregulated in psoriatic skin. These two miRNAs are able to inhibit proliferation while promote differentiation of psoriatic keratinocytes, and miR-125b can also suppress inflammation in psoriatic lesions. By analyzing the contexts related to these miRNAs, we found that each of them does not act alone but rather work in concert with other miRNAs. The imbalance between miR-31/miR-203and hsa-miR-99a/miR-125b may contribute to the intense proliferation and abnormal differentiation of psoriatic keratinocytes, which is a characteristic of pathogenesis of psoriasis.

CONCLUSION

An imbalanced miRNAs axis was for the first time outlined. Apparently, upregulation of miR-31/miR-203 and downregulation of hsa-miR-99a/miR-125b work together in concert to facilitate the development of psoriasis pathogenesis. Further work in this field holds the potentials to open a new way to study psoriasis.

Models in the Research Process of Psoriasis

Psoriasis is an ancient, universal chronic skin disease with a significant geographical variability, with the lowest incidence rate at the equator, increasing towards the poles. Insights into the mechanisms responsible for psoriasis have generated an increasing number of druggable targets and molecular drugs. The development of relevant in vitro and in vivo models of psoriasis is now a priority and an important step towards its cure. In this review, we summarize the current cellular and animal systems suited to the study of psoriasis. We discuss the strengths and limitations of the various models and the lessons learned. We conclude that, so far, there is no one model that can meet all of the research needs. Therefore, the choice model system will depend on the questions being addressed.

Towards topical microRNA-directed therapy for epidermal disorders

There remains an unmet dermatological need for innovative topical agents that achieve better longterm outcomes with fewer side effects. Modulation of the expression and activity of microRNA (miRNAs) represents an emerging translational framework for the development of such innovative therapies because changes in the expression of one miRNA can have wide-ranging effects on diverse cellular processes associated with disease. In this short review, the roles of miRNA in epidermal development, psoriasis, cutaneous squamous cell carcinoma and re-epithelisation are highlighted. Consideration is given to the delivery of oligonucleotides that mimic or inhibit miRNA function using vehicles such as cell penetrating peptides, spherical nucleic acids, deformable liposomes and liquid crystalline nanodispersions. Formulation of miRNA-directed oligonucleotides with such skin-penetrating epidermal agents will drive the development of RNA-based cutaneous therapeutics for deployment as primary or adjuvant therapies for epidermal disorders.

Advances in the Application and Impact of MicroRNAs as Therapies for Skin Disease

The advent of RNA interference (RNAi) technology has profoundly impacted molecular biology research and medicine but has also advanced the field of skin care. Both effector molecules of RNAi, short-interfering RNA molecules and microRNAs (miRNAs), have been explored for their relative impact and utility for treating a variety of skin conditions. These post-transcriptional RNA regulatory molecules down-modulate protein expression through targeting of the 3' untranslated regions of messenger RNAs, leading to their degradation or repression through sequestration. As researchers hunt for genetic linkages to skin diseases, miRNA regulators have emerged as key players in the biology of keratinocytes, fibroblasts, melanocytes, and other cells of the skin. Herein, we attempt to coalesce the current efforts to combat various skin disorders and diseases through the development of miRNA-based technologies.

In vitro psoriasis models with focus on reconstructed skin models as promising tools in psoriasis research

Psoriasis is a complex chronic immune-mediated inflammatory cutaneous disease associated with the development of inflammatory plaques on the skin. Studies proved that the disease results from a deregulated interplay between skin keratinocytes, immune cells and the environment leading to a persisting inflammatory process modulated by pro-inflammatory cytokines and activation of T cells. However, a major hindrance to study the pathogenesis of psoriasis more in depth and subsequent development of novel therapies is the lack of suitable pre-clinical models mimicking the complex phenotype of this skin disorder. Recent advances in and optimization of three-dimensional skin equivalent models have made them attractive and promising alternatives to the simplistic monolayer cultures, immunological different in vivo models and scarce ex vivo skin explants. Moreover, human skin equivalents are increasing in complexity level to match human biology as closely as possible. Here, we critically review the different types of three-dimensional skin models of psoriasis with relevance to their application potential and advantages over other models. This will guide researchers in choosing the most suitable psoriasis skin model for therapeutic drug testing (including gene therapy via siRNA molecules), or to examine biological features contributing to the pathology of psoriasis. However, the addition of T cells (as recently applied to a de-epidermized dermis-based psoriatic skin model) or other immune cells would make them even more attractive models and broaden their application potential. Eventually, the ultimate goal would be to substitute animal models by three-dimensional psoriatic skin models in the pre-clinical phases of anti-psoriasis candidate drugs. Impact statement The continuous development of novel in vitro models mimicking the psoriasis phenotype is important in the field of psoriasis research, as currently no model exists that completely matches the in vivo psoriasis skin or the disease pathology. This work provides a complete overview of the different available in vitro psoriasis models and suggests improvements for future models. Moreover, a focus was given to psoriatic skin equivalent models, as they offer several advantages over the other models, including commercial availability and validity. The potential and reported applicability of these models in psoriasis pre-clinical research is extensively discussed. As such, this work offers a guide to researchers in their choice of pre-clinical psoriasis model depending on their type of research question.

Effects of RNA interference combined with ultrasonic irradiation and SonoVue microbubbles on expression of STAT3 gene in keratinocytes of psoriatic lesions

The most effective sequence of small interfering RNA (siRNA) silencing STAT3 of psoriatic keratinocytes (KCs) was screened out, and the effects of the most effective siRNA combined with ultrasonic irradiation and SonoVue microbubbles on the expression of STAT3 of KCs and the dose- and time-response were investigated. Three chemically-synthetic siRNAs targeting STAT3 carried by Lipofectamine 3000 were transfected into KCs, and the effects on STAT3 expression were detected, then the most effective siRNA was selected for the subsequent experiments. The negative controls of siRNA (siRNA-NC) labeled with Cy3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles were transfected into KCs, then the optimal parameters of ultrasonic irradiation were determined. The most effective siRNA carried by Li-pofectamine 3000 combined with ultrasonic irradiation at the optimal parameters and SonoVue microbubbles was transfected into KCs, and the dose- and time-response of RNA interference was determined. The effect of RNA interference by the most effective siRNA at the optimal time and dose carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group) was compared with that only carried by Li-pofectamine 3000 (L group). The results showed that siRNA-3 achieved the highest silencing efficacy. 0.5 W/cm2 and 30 s were selected as the parameters of ultrasonic irradiation. The siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression at mRNA and protein levels in dose- and time-dependent manners determined at 100 nmol/L with maximum downregulation on mRNA at 48 h, and on protein at 72 h after transfection. The LUS group achieved the highest silencing efficacy. It was concluded that siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression in psoriatic KCs, and the optimized transfection condition and the sequence of siRNA-3 could serve for further research on gene therapy of psoriasis.

JAK3 as an Emerging Target for Topical Treatment of Inflammatory Skin Diseases

The recent interest and elucidation of the JAK/STAT signaling pathway created new targets for the treatment of inflammatory skin diseases (ISDs). JAK inhibitors in oral and topical formulations have shown beneficial results in psoriasis and alopecia areata. Patients suffering from other ISDs might also benefit from JAK inhibition. Given the development of specific JAK inhibitors, the expression patterns of JAKs in different ISDs needs to be clarified. We aimed to analyze the expression of JAK/STAT family members in a set of prevalent ISDs: psoriasis, lichen planus (LP), cutaneous lupus erythematosus (CLE), atopic dermatitis (AD), pyoderma gangrenosum (PG) and alopecia areata (AA) versus healthy controls for (p)JAK1, (p)JAK2, (p)JAK3, (p)TYK2, pSTAT1, pSTAT2 and pSTAT3. The epidermis carried in all ISDs, except for CLE, a strong JAK3 signature. The dermal infiltrate showed a more diverse expression pattern. JAK1, JAK2 and JAK3 were significantly overexpressed in PG and AD suggesting the need for pan-JAK inhibitors. In contrast, psoriasis and LP showed only JAK1 and JAK3 upregulation, while AA and CLE were characterized by a single dermal JAK signal (pJAK3 and pJAK1, respectively). This indicates that the latter diseases may benefit from more targeted JAK inhibitors. Our in vitro keratinocyte psoriasis model displayed reversal of the psoriatic JAK profile following tofacitinib treatment. This direct interaction with keratinocytes may decrease the need for deep skin penetration of topical JAK inhibitors in order to exert its effects on dermal immune cells. In conclusion, these results point to the important contribution of the JAK/STAT pathway in several ISDs. Considering the epidermal JAK3 expression levels, great interest should go to the investigation of topical JAK3 inhibitors as therapeutic option of ISDs.

MicroRNA-181b negatively regulates the proliferation of human epidermal keratinocytes in psoriasis through targeting TLR4

Our study aims to explore the role of microRNA‐181b (miR‐181b) and TLR in the regulation of cell proliferation of human epidermal keratinocytes (HEKs) in psoriasis. Twenty‐eight patients diagnosed with psoriasis vulgaris were selected as a case group with their lesional and non‐lesional skin tissues collected. A control group consisted of 20 patients who underwent plastic surgery with their healthy skin tissues collected. Real‐time quantitative fluorescence polymerase chain reaction (RT‐qPCR), in situ hybridization and immunohistochemistry were used to detect the expressions of miR‐181b and TLR4 in HEKs of healthy skin, psoriatic lesional skin and non‐lesional skin respectively. The 3′ untranslated region (3′UTR) of TLR4 combined with miR‐181b was verified by a dual‐luciferase reporter assay. Western blotting and bromodeoxyuridine were applied for corresponding detection of TLR4 expression and cell mitosis. The expression of miR‐181b in HEKs of psoriatic lesional skin was less than healthy skin and psoriatic non‐lesional skin. In psoriatic lesional and non‐lesional skin, TLR4‐positive cell rates and the number of positive cells per square millimetre were higher than healthy skin. The dual‐luciferase reporter assay verified that miR‐181b targets TLR4. HEKs transfected with miR‐181b mimics had decreased expression of TLR4, along with the decrease of mitotic indexes and Brdu labelling indexes. However, HEKs transfected with miR‐181b inhibitors showed increased TLR4 expression, mitotic indexes and Brdu labelling indexes. HEKs transfected with both miR‐181b inhibitors and siTLR4 had decreased mitotic indexes and Brdu labelling indexes. These results indicate that miR‐181b can negatively regulate the proliferation of HEKs in psoriasis by targeting TLR4.

Tissue-engineered human psoriatic skin supplemented with cytokines as an in vitro model to study plaque psoriasis

AIM

Psoriasis is a chronic inflammatory skin disease. To study its complex etiology, a psoriatic skin substitute model supplemented with a cytokine cocktail has been used.

MATERIALS & METHODS

Reconstructed psoriatic skin substitutes were supplemented with a cocktail of four cytokines: TNF-α, IL-1α, IL-6 and IL-17A, to monitor their impact on gene expression by DNA microarray.

RESULTS

Gene profiling analyses identified several deregulated genes reported as being also deregulated in psoriasis skin in vivo (S100A12, IL-8, DEFB4A and KYNU). The expression of those genes was dramatically increased compared with basal levels of controls (p < 0.005 to < 0.05).

CONCLUSION

Psoriatic substitutes supplemented with a cocktail of TNF-α, IL-1α, IL-6 and IL-17A showed similar transcriptome alterations to those found in psoriasis.

Characterization data on the topical carrier DDC642

This article contains original data, figures and methods used in the characterization of the liposomal carrier ‘DDC642’ for topical applications, described in “An elastic liposomal formulation for RNAi-based topical treatment of skin disorders: proof-of-concept in the treatment of psoriasis” (Desmet et al., 2016) [1]. Several elastic liposomal formulations have been evaluated for their ability to encapsulate and deliver RNA interference (RNAi) molecules to cultured primary skin cells. The efficiency and effectiveness of these liposomes were compared to that of our previously characterized liposomes, the ‘SECosomes’ (SEC) (Geusens et al., 2010) [2]. After selection of a potential superior carrier, based on encapsulation and transfection efficiency data (Desmet et al., 2016) [1], the selected DDC642 liposomes were characterized more in-depth. Herein, a detailed characterization of the DDC642 liposome and RNAi-loaded lipoplexes is given, including the matching protocols.

An elastic liposomal formulation for RNAi-based topical treatment of skin disorders: Proof-of-concept in the treatment of psoriasis

RNA interference (RNAi) is a rapidly emerging approach for targeted gene silencing to alleviate disease pathology. However, lack of efficient carriers for targeted delivery delays the clinical translation of RNAi. An interesting target for local RNAi therapeutics is the skin as it allows direct access to target cells. Still, applications are limited due to the effective skin barrier which hinders penetration. Herein, a description is given of a liposomal carrier, called 'DDC642', capable of delivering RNAi molecules to the epidermis of impaired and intact human skin, without targeting the dermis or circulatory system. In a psoriasis tissue model, down-regulation of the psoriasis marker human beta-defensin 2 by DDC642-delivered siRNA was confirmed, providing proof-of-concept. These liposomes thus hold great potential as topical delivery system for RNAi therapeutics in the treatment of numerous skin diseases.

An Exploration of the Role of MicroRNAs in Psoriasis: A Systematic Review of the Literature

Psoriasis is recently characterized by a specific microRNAs (miRNAs) expression profile, which guides the researchers' efforts to explore the therapeutic targets and objective biomarkers that reflect the diagnosis and disease activity in clinical use for psoriasis.The paper presents a state-of-the-art review of expression and function of miRNAs in psoriasis along with its clinical implications.We analyzed all literature searched by keywords "microRNA" and "psoriasis" in PubMed (Medline) from inception up to July 2015, and the references in the literature searched were also considered.Relevant literature was chosen according to the objective of this review. Relevant literature was searched by 3 independent investigators, and experts in the field of miRNAs and psoriasis were involved in analyzing process.We included any study in which role of miRNAs in psoriasis was examined in relation to disease pathogenesis, diagnosis, and treatment.The specific miRNAs profile has been identified from human psoriatic skin, blood, and hair samples. It is found that genetic polymorphisms related to some of specific miRNAs, miR-146a for example, are associated with psoriasis susceptibility. Key roles of several unique miRNAs, such as miR-203 and miR-125b, in inflammatory responses and immune dysfunction, as well as hyperproliferative disorders of psoriatic lesions have been revealed. Moreover, circulating miRNAs detected from blood samples have a potential of clinic application to be the biomarkers of diagnosis, prognosis, and treatment responses. Additionally, a new layer of regulatory mechanisms mediated by miRNAs is to some extent revealed in pathogenesis of psoriasis.The dramatically altered mRNA expression profiles are displayed in psoriasis, and some of these may become disease markers and therapeutic targets. Herein, this work underscores the potential importance of miRNAs to diagnosis, prognosis, and treatment of psoriasis. However, further study in this field is worth doing in the future, as the exact roles of miRNAs in psoriasis have not been fully elucidated.Systematic review registration number is not registered.