Notch-1 mediates endothelial cell activation and invasion in psoriasis

Targeted siRNA Therapy for Psoriasis: Translating Preclinical Potential into Clinical Treatments

Psoriasis is a chronic inflammatory skin disease characterized by the excessive proliferation of keratinocytes and heightened immune activation. Targeting pathogenic genes through small interfering RNA (siRNA) therapy represents a promising strategy for the treatment of psoriasis. This mini-review provides a comprehensive summary of siRNA research targeting the pathogenesis of psoriasis, covering aspects such as keratinocyte function, inflammatory cell roles, preclinical animal studies, and siRNA delivery mechanisms. It details recent advancements in RNA interference that modulate key factors including keratinocyte proliferation (Fibroblast Growth Factor Receptor 2, FGFR2), apoptosis (Interferon Alpha Inducible Protein 6, G1P3), differentiation (Grainyhead Like Transcription Factor 2, GRHL2), and angiogenesis (Vascular Endothelial Growth Factor, VEGF); immune cell infiltration and inflammation (Tumor Necrosis Factor-Alpha, TNF-α; Interleukin-17, IL-17); and signaling pathways (JAK-STAT, Nuclear Factor Kappa B, NF-κB) that govern immunopathology. Despite significant advances in siRNA-targeted treatments for psoriasis, several challenges persist. Continued scientific developments promise the creation of more effective and safer siRNA medications, potentially enhancing the quality of life for psoriasis patients and revolutionizing treatments for other diseases. This article focuses on the most recent research advancements in targeting the pathogenesis of psoriasis with siRNA and explores its future therapeutic prospects.

Cycloastragenol restrains keratinocyte hyperproliferation by promoting autophagy via the miR-145/STC1/Notch1 axis in psoriasis

BACKGROUND

Psoriasis is characterized by inflammation and hyperproliferation of epidermal keratinocytes. Cycloastragenol (CAG) is an active molecule of Astragalus membranaceus that potentially plays a repressive role in psoriasis. Activated cell autophagy is an effective pathway for alleviating psoriasis progression. Thus, we investigated the role of CAG in the proliferation and autophagy of interleukin (IL)-22-stimulated keratinocytes.

METHODS

A psoriasis model was established by stimulating HaCaT cells with IL-22. Gene or protein expression levels were measured by qRT-PCR or western blot. Autophagy flux was observed with mRFP-GFP-LC3 adenovirus transfection assay under confocal microscopy. Stanniocalcin-1 (STC1) secretion levels were determined using ELISA kits. The apoptosis rate was assessed using flow cytometry. Interactions between miR-145 and STC1 or STC1 and Notch1 were validated by luciferase reporter gene assays, RIP, and Co-IP assays.

RESULTS

CAG repressed cell proliferation and promoted apoptosis and autophagy in IL-22-stimulated HaCaT cells. Additionally, CAG promoted autophagy by enhancing miR-145. STC1 silencing ameliorated autophagy repression in IL-22-treated HaCaT cells. Moreover, miR-145 negatively regulated STC1, and STC1 was found to activate Notch1. Lastly, STC1 overexpression reversed CAG-promoted autophagy.

CONCLUSION

CAG alleviated keratinocyte hyperproliferation through autophagy enhancement via regulating the miR-145/STC1/Notch1 axis in psoriasis.

The Genomic Architecture of Hidradenitis Suppurativa-A Systematic Review

Hidradenitis suppurativa is a chronic, suppurative condition of the pilosebaceous unit manifesting as painful nodules, abscesses, and sinus tracts mostly in, but not limited to, intertriginous skin. Great strides have been made at elucidating the pathophysiology of hidradenitis suppurativa, which appears to be the product of hyperkeratinization and inflammation brought about by environmental factors and a genetic predisposition. The identification of familial hidradenitis suppurativa has sparked research aimed at identifying underlying pathogenic variants in patients who harbor them. The objective of this review is to provide a broad overview of the role of genetics in various aspects of hidradenitis suppurativa, specifically the pathophysiology, diagnosis, and clinical application.

Circulating Metabolomic Signature in Generalized Pustular Psoriasis Blunts Monocyte Hyperinflammation by Triggering Amino Acid Response

Generalized pustular psoriasis (GPP), the most grievous variant of psoriasis, is featured by dysregulated systemic inflammatory response. The cellular and molecular basis of GPP is poorly understood. Blood monocytes are key players of host defense and producers of inflammatory cytokines including IL-1β. How the immune response of monocytes is affected by metabolic internal environment in GPP remains unclear. Here, we performed a metabolomic and functional investigation of GPP serum and monocytes. We demonstrated a significant increase in IL-1β production from GPP monocytes. In GPP circulation, serum amyloid A (SAA), an acute-phase reactant, was dramatically increased, which induced the release of IL-1β from monocytes in a NLRP3-dependent manner. Using metabolomic analysis, we showed that GPP serum exhibited an amino acid starvation signature, with glycine, histidine, asparagine, methionine, threonine, lysine, valine, isoleucine, tryptophan, tyrosine, alanine, proline, taurine and cystathionine being markedly downregulated. In functional assay, under amino acid starvation condition, SAA-stimulated mature IL-1β secretion was suppressed. Mechanistically, at post-transcriptional level, amino acid starvation inhibited the SAA-mediated reactive oxygen species (ROS) formation and NLRP3 inflammasome activation. Moreover, the immune-modulatory effect of amino acid starvation was blocked by silencing general control nonderepressible 2 kinase (GCN2), suggesting the involvement of amino acid response (AAR) pathway. Collectively, our results suggested that decreased serum amino acids in GPP blunted the innate immune response in blood monocytes through AAR pathway, serving as a feedback mechanism preventing excessive inflammation in GPP.

The Genetic Variants of NOTCH3 (6746T>C) and PSMA6 (-8C>G) as Possible Risk Factors of Psoriasis Development

Advances in genotypic technologies enable identification of possible associations between genetic variants of certain genes and increased risk of developing plaque psoriasis or psoriatic arthritis. The aim of the study was to analyze the NOTCH3 (6746T>C) (rs1044009) and PSMA6 (-8C>G) (rs1048990) polymorphisms and their role in genetic susceptibility to psoriasis. The study included 158 psoriatic patients and 100 healthy controls. The frequencies of the NOTCH3 genotypes differed between the psoriatic patients and healthy controls (p = 0.050). No differences were found in the distribution of PSMA6 genotypes and alleles between the psoriatic patients and healthy controls. The studied psoriatic patients presented a higher frequency of the CC genotype of PSMA6 compared to the healthy controls (8.8% vs. 2%, respectively). Psoriatic arthritis was more frequent among patients with the CC genotype of PSMA6 (p = 0.059). CC homozygosity of NOTCH3 was more commonly observed in the studied psoriatic patients than in the healthy controls (OR = 4.76, p= 0.032). The obtained data suggest that genetic variants of NOTCH3 (6746T>C) and PSMA6 (-8C>G) genes may play significant roles in psoriatic patients. Further studies are necessary to unequivocally determine their role as genetic risk factors of psoriasis development.

LncRNA Xist Contributes to Endogenous Neurological Repair After Chronic Compressive Spinal Cord Injury by Promoting Angiogenesis Through the miR-32-5p/Notch-1 Axis

Endogenous repair after chronic compressive spinal cord injury (CCSCI) is of great clinical interest. Ischemia-hypoxia-induced angiogenesis has been proposed to play an important role during this repair process. Emerging evidence indicates that long non-coding RNAs (lncRNAs) are involved in the pathophysiological processes of various diseases. Here, we identified a lncRNA (Xist; X-inactive specific transcript) with upregulated expression in cervical spine lesions during endogenous neurological repair in CCSCI rats. Therapeutically, the introduction of Xist to rats increased neurological function in vivo as assayed using the Basso, Beattie, and Bresnahan (BBB) score and inclined plane test (IPT). We found that the introduction of Xist enhanced endogenous neurological repair by promoting angiogenesis and microvessel density after CCSCI, while depletion of Xist inhibited angiogenesis and cell sprouting and migration. Mechanistically, Xist promoted angiogenesis by sponging miR-32-5p and modulating Notch-1 expression both in vitro and in vivo. These findings suggest a role of the Xist/miR-32-5p/Notch-1 axis in endogenous repair and provide a potential molecular target for the treatment of ischemia-related central nervous system (CNS) diseases.

Pleiotropic Role of Notch Signaling in Human Skin Diseases

Notch signaling orchestrates the regulation of cell proliferation, differentiation, migration and apoptosis of epidermal cells by strictly interacting with other cellular pathways. Any disruption of Notch signaling, either due to direct mutations or to an aberrant regulation of genes involved in the signaling route, might lead to both hyper- or hypo-activation of Notch signaling molecules and of target genes, ultimately inducing the onset of skin diseases. The mechanisms through which Notch contributes to the pathogenesis of skin diseases are multiple and still not fully understood. So far, Notch signaling alterations have been reported for five human skin diseases, suggesting the involvement of Notch in their pathogenesis: Hidradenitis Suppurativa, Dowling Degos Disease, Adams-Oliver Syndrome, Psoriasis and Atopic Dermatitis. In this review, we aim at describing the role of Notch signaling in the skin, particularly focusing on the principal consequences associated with its alterations in these five human skin diseases, in order to reorganize the current knowledge and to identify potential cellular mechanisms in common between these pathologies.

Notch-Hes1 Signaling Regulates IL-17A+ γδ +T Cell Expression and IL-17A Secretion of Mouse Psoriasis-Like Skin Inflammation

Purpose

To evaluate the regulating effect of Notch-Hes1 signaling on IL-17A⁺γδ⁺T cell expression and IL-17A secretion in mouse psoriasis-like skin inflammation.

Materials and Methods

Experimental mice were randomly divided into control group, model group (5% imiquimod- (IMQ-) treated mice), and intervention group (IMQ and γ-secretase inhibitor DAPT cotreated mice). The severity of psoriasis-like skin inflammation was evaluated by target lesion score based on the clinical psoriasis area and severity index (PASI). Flow cytometry detected IL-17A⁺γδ⁺T cell percentage. Quantitative real-time RT-PCR detected Hes1 mRNA expression. Enzyme-linked immunosorbent assay and western blot measured IL-17A serum concentration and protein expression. Additionally, splenic single cells from model mice were treated by DAPT to further evaluate the inhibitory effect of blocking Notch-Hes1 signaling on IL-17A⁺γδ⁺T cell differentiation and IL-17A secretion.

Results

The spleen index, IL-17A⁺γδ⁺T cell percentage, Hes1 mRNA expression, IL-17A serum concentration, and protein expression were all significantly higher in model mice than control mice, while dramatically reduced in intervention mice by DAPT treatment, which also obviously alleviated the target lesion score, epidermal hyperplasia, and dermal inflammatory cell infiltration of intervention mice. In vitro study demonstrated that DAPT treatment could result in dose-dependent decrease of IL-17A⁺γδ⁺T cell percentage and IL-17A secretion in splenic single cells of model mice.

miR‑125b‑mediated regulation of cell proliferation through the Jagged‑1/Notch signaling pathway by inhibiting BRD4 expression in psoriasis

Psoriasis is a chronic inflammatory disease characterized by the abnormal differentiation and hyperproliferation of epidermal keratinocytes. The aim of the present study was to investigate the mechanism by which microRNA‑125b (miR‑125b) inhibits the activation of the bromodomain‑containing protein 4 (BRD4)/Notch signaling pathway in psoriasis. The contents of associated miRNAs in serum samples from 32 patients with psoriasis were detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The most significantly downregulated miRNA, miR‑125b, was screened out. In experiments using HaCaT cells, the association between miR‑125b and cell proliferation was observed using a Cell Counting Kit‑8 assay, that between miR‑125b and the Notch signaling pathway was observed by western blotting and RT‑qPCR, and that between miR‑125b and the upstream molecule BRD4 of the Notch signaling pathway was observed by luciferase reporter assay and western blotting. The proliferation of HaCaT cells became apparent following miR‑125b inhibition. The Jagged‑1 ligand in the Notch signaling pathway was upregulated, the active intracellular domain of the Notch1 receptor was increasingly truncated, and the Notch signaling pathway was activated. Furthermore, the inhibited miR‑125b contributed directly toward the upstream protein BRD4 3'‑UTR of Jagged‑1, ultimately activating the Notch signaling pathway with the upregulation of Jagged‑1. In conclusion, the proliferation of HaCaT cells mediated by the Jagged‑1/Notch signaling pathway was decreased with the miR‑125b‑mediated inhibition of BRD4 expression. Therefore, miR‑125b may be a biomarker and potential therapeutic target for psoriasis treatment.

Dermal mesenchymal stem cells: a resource of migration-associated function in psoriasis?

BACKGROUND

Psoriasis is a chronic and systemic, immune-mediated, inflammatory disease. Mesenchymal stem cells have effects on the inflammatory microenvironment, including regulating the proliferation, differentiation, recruitment, and migration of immunocytes.

METHODS

To investigate whether dermal mesenchymal stem cells (DMSCs) may act on migration of immunocytes in psoriasis patients, 22 patients with psoriasis and 22 matching healthy controls (age and sex in this study) were recruited. Seven migration-associated genes including chemokine like receptor-1 (CMKLR-1), collagen type VIII alpha1 (COL8A-1), neuropilin and tolloid-like 2 (NETO-2), nik-related kinase (NRK), secreted frizzled-related protein (SFRP), sulfate 6-O-endosulfatase 2 (SULF-2), and synaptotagmin-like protein 2 (SYTL-2) were analyzed by quantitative real-time reverse transcription PCR and western blot. Peripheral blood-derived mononuclear cells (PBMCs) migration to MSCs was measured using a Thanswell chamber system.

RESULTS

We observed the upregulation of CMKLR-1, COL8A-1, NETO-2, NRK, SYTL-2, and SULF-2 in dermal mesenchymal stem cells derived from patients with psoriasis at both mRNA and protein level, however, a significant downregulation of SFRP-2 between two groups. By contrast, there were no significant between-group differences at the mRNA and protein expression level of NETO-2 and SULF-2. The migration assay showed that in vitro the normal PBMC migration to psoriatic DMSC group was a 6.3 ± 0.7-fold increase compared with the control group.

CONCLUSIONS

The results may suggest a potential pathogenetic involvement of DMSCs on migration of monocytes in psoriasis. Immune responses are regulated at the level of DMSCs, which probably represent the cells primarily involved in the "psoriatic march."

Notch Signaling in Endothelial Cells: Is It the Therapeutic Target for Vascular Neointimal Hyperplasia?

Blood vessels respond to injury through a healing process that includes neointimal hyperplasia. The vascular endothelium is a monolayer of cells that separates the outer vascular wall from the inner circulating blood. The disruption and exposure of endothelial cells (ECs) to subintimal components initiate the neointimal formation. ECs not only act as a highly selective barrier to prevent early pathological changes of neointimal hyperplasia, but also synthesize and release molecules to maintain vascular homeostasis. After vascular injury, ECs exhibit varied responses, including proliferation, regeneration, apoptosis, phenotypic switching, interacting with other cells by direct contact or secreted molecules and the change of barrier function. This brief review presents the functional role of the evolutionarily-conserved Notch pathway in neointimal hyperplasia, notably by regulating endothelial cell functions (proliferation, regeneration, apoptosis, differentiation, cell-cell interaction). Understanding endothelial cell biology should help us define methods to prompt cell proliferation, prevent cell apoptosis and dysfunction, block neointimal hyperplasia and vessel narrowing.

Serum amyloid A, an acute phase protein, stimulates proliferative and proinflammatory responses of keratinocytes

OBJECTIVES

Serum amyloid A (SAA), an acute phase protein, is highly expressed in psoriatic lesions but its function is not fully understood. The aim of this study was to explore its role in activation of keratinocytes.

MATERIALS AND METHODS

Real-time PCR and immunofluorescence were performed to examine SAA expression in imiquimod (IMQ)-induced psoriasis-like mice. In vivo function of SAA was examined by treating psoriasis-like mice with SAA neutralising antibody. Cell viability was monitored using the CCK-8 assay. Real-time PCR was performed to determine expression of genes associated with differentiation and inflammation. Ki67⁺ percentage and immunological markers were analysed by flow cytometry. Involvement of formyl peptide receptor-like 1 (FPRL1) in SAA signal transduction was determined by RNA interference. Binding of SAA and FPRL1 was examined by co-immunoprecipitaion. Western blotting was conducted to assess phosphorylation of downstream signalling molecules.

RESULTS

SAA was highly expressed in skin lesions of IMQ-treated psoriasis-like mice and neutralising SAA attenuated epidermal hyperplasia and inflammation. SAA in vitro promoted keratinocyte proliferation and expression of immunological mediators, while inhibiting differentiation. Effects of SAA on keratinocyte proliferation and inflammation were mediated by FPRL1, as well as activation of the PI3K/Akt pathway.

CONCLUSIONS

These observations indicate that SAA/FPRL1 contributed to pathogenesis of psoriasis by promoting keratinocyte proliferation and inflammation, thus providing a potential therapeutic target for disease therapy.

Effect of 12-O-tetradecanoylphorbol-13-acetate-induced psoriasis-like skin lesions on systemic inflammation and atherosclerosis in hypercholesterolaemic apolipoprotein E deficient mice

Background

Risk of cardiovascular disease is increased in patients with psoriasis, but molecular mechanisms linking the two conditions have not been clearly established. Lack of appropriate animal models has hampered generation of new knowledge in this area of research and we therefore sought to develop an animal model with combined atherosclerosis and psoriasis-like skin inflammation.

Methods

Topical 12-O-tetradecanoylphorbol-13-acetate (TPA) was applied to the ears twice per week for 8 weeks in atherosclerosis-prone apolipoprotein E deficient (ApoE^−/−) mice.

Results

TPA led to localized skin inflammation with increased epidermal thickness, infiltration of inflammatory-like cells and augmented tissue interleukin-17F levels. Systemic effects of the topical application of TPA were demonstrated by increased plasma concentration of serum amyloid A and splenic immune modulation, respectively. However, atherosclerotic plaque area and composition, and mRNA levels of several inflammatory genes in the aortic wall were not significantly affected by TPA-induced skin inflammation.

Conclusions

TPA-induced psoriasis-like skin inflammation in atherosclerosis-prone ApoE^−/− mice evoked systemic immune-inflammatory effects, but did not affect atherogenesis. The results may question the role of psoriasis-induced inflammation in the pathogenesis of atherosclerosis in psoriasis patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12895-016-0046-1) contains supplementary material, which is available to authorized users.

Wheat germ agglutinin as a counterstain for immunofluorescence studies of equine hoof lamellae

Equine laminitis is a common, painful, debilitating condition of the hoof that is a leading cause of disability in horses, often necessitating euthanasia. The equine hoof represents an extreme evolutionary adaptation of an epidermal structure homologous to the human or murine nail units. Immunohistochemistry is frequently utilized in the study of the pathophysiology of laminitis. The complex, multilayered, extensively interdigitated epidermal-dermal lamellar interface renders precise interpretation of immunofluorescence localization difficult, especially when effective technique and reagents render non-reactive tissues completely dark. Fluorescent-conjugated wheat germ agglutinin (WGA) selectively labels dermal extracellular matrix fibres and epidermal cell membranes in tissue sections of horse hoof lamellae, is compatible with indirect immunofluorescence and augments interpretation of indirect immunofluorescence antigen localization. The current report details the use of WGA as a rapid, simple, economical counterstain for immunofluorescence studies of the equine hoof and may have application to other complex epidermal tissue structures.

Interaction of Wnt5a with Notch1 is Critical for the Pathogenesis of Psoriasis

Background

Psoriasis is characterized by uncontrolled hyperproliferation, aberrant differentiation, and dermal infiltration of immune cells. Recent studies have reported that Wnt5a and Notch1 signaling are altered in psoriatic skin lesions.

Objective

We aimed to investigate the interaction of Wnt5a with Notch 1 with respect to inflammation-mediated epidermal hyperproliferation in psoriasis.

Methods

Expression of Wnt5a and Notch1 signaling-related proteins were examined in psoriatic skin biopsies. Wnt5a was upregulated in human keratinocytes by treating the cells with its recombinant form (rWnt5a).

Results

In psoriatic lesions, expression of Wnt5a increased while that of Notch1 decreased when compared to that in non-lesional and normal skin. Treatment with rWnt5a increased the proliferation of keratinocytes and increased their secretion of interleukin (IL)-23, IL-12, and tumor necrosis factor (TNF)-α. Further, exposure of keratinocytes to IL-1α, TNF-α, transforming growth factor-α, and interferon-γ downregulated Notch1 as well as HES 1, which is downstream to Notch1, but increased the Wnt5a levels. The upregulated Wnt5a in keratinocytes downregulated both Notch1 and HES1.

Conclusion

Our data suggest that Wnt5a and Notch1 signaling exert counteracting influences on each other and are involved, in part, in the pathomechanism of psoriasis.

Serum amyloid A induces interleukin-1β secretion from keratinocytes via the NACHT, LRR and PYD domains-containing protein 3 inflammasome

Interleukin (IL)-1β is now emerging as a critical cytokine in the pathogenesis of T helper type 17 (Th17)-mediated skin diseases, including psoriasis. Psoriatic keratinocytes are a major source of IL-1β; however, the mechanisms triggering IL-1β processing remain unknown. Recently, an acute-phase protein serum amyloid A (SAA) has been identified as a danger signal that triggers inflammasome activation and IL-1β secretion. In this study, we detected increased SAA mRNA and protein expression in psoriatic epidermis. In cultured keratinocytes, SAA up-regulated the expression of pro-IL-1β and secretion of mature IL-1β. On the transcriptional level, blocking Toll-like receptor-2 (TLR-2), TLR-4 or nuclear factor kappa B (NF-κB) attenuated SAA-induced expression of IL-1β mRNA. SAA up-regulated caspase-1 and NACHT, LRR and PYD domains-containing protein 3 (NLRP3) expression in keratinocytes. Inhibiting caspase-1 activity and silencing NLRP3 decreased IL-1β secretion, confirming NLRP3 as the SAA-responsive inflammasome on the post-transcriptional level. The mechanism of SAA-triggered NLRP3 activation and subsequent IL-1β secretion was found to involve the generation of reactive oxygen species. Finally, the expression of SAA by keratinocytes was up-regulated by IL-17A. Taken together, our results indicate that keratinocyte-derived SAA triggers a key inflammatory mediator, IL-1β, via NLRP3 inflammasome activation, providing new potential targets for the treatment of this chronic skin disease.

Systemic inflammation and imbalance between endothelial injury and repair in patients with psoriasis are associated with preclinical atherosclerosis

BACKGROUND

Systemic inflammation and imbalance between endothelial injury and repair, the latter referred to as vascular incompetence, are associated with atherosclerosis and cardiovascular risk. Psoriasis, an inflammatory disease of the skin, has been associated with atherosclerosis. We investigated whether, in psoriasis, inflammation and vascular incompetence are associated with carotid intima-media thickness (cIMT) irrespective of metabolic syndrome and other established cardiovascular risk factors.

METHODS

High sensitivity C-reactive protein (hsCRP), the ratio between endothelial microparticles (EMPs) and progenitors (EPCs), a marker of vascular incompetence, and cIMT were measured in 84 patients with psoriasis and 90 healthy controls, balanced for age, gender and the prevalence of metabolic syndrome.

RESULTS

Patients with psoriasis had higher hsCRP, EMP/EPC ratio and cIMT than controls. Patients with both psoriasis and metabolic syndrome had the highest hsCRP levels, psoriasis and metabolic syndrome being associated with a 3.1- and 2.6-fold increased risk of having high hsCRP levels, respectively. Logarithm transformed hsCRP and EMP/EPC ratio were predictors of high cIMT (odds ratio 3.8; 95% confidence interval 1.3-11.4; p = 0.02 and odds ratio 8.7; 95% confidence interval 2.7-27.5; p < 0.001, respectively) regardless of confounders. Patients with high hsCRP and EMP/EPC ratio had higher cIMT than those with none or at least one of risk variable.

CONCLUSIONS

Patients with psoriasis have an increased burden of cardiovascular risk, including inflammation, vascular incompetence and early atherosclerosis. Increased hsCRP levels, possibly sustained by the inflammatory nature of psoriasis and metabolic syndrome, and vascular incompetence are associated with early carotid atherosclerosis, regardless of metabolic syndrome and other established cardiovascular risk factors.