Psoriatic Keratinocytes Research Articles

Pioneers in Dermatology and Venereology: an interview with Prof. Louis M.M. Dubertret

Pioneers in Dermatology and Venereology: an interview with Prof. Louis M.M. Dubertret

Intracellular Insulin-like growth factor binding protein 2 (IGFBP2) contributes to the senescence of keratinocytes in psoriasis by stabilizing cytoplasmic p21.

Psoriasis is a chronic Th1/Th17 lymphocytes-mediated inflammatory skin disease, in which epidermal keratinocytes exhibit a peculiar senescent state, resistance to apoptosis and the acquisition of senescence-associated secretory phenotype (SASP). SASP consists of the release of soluble factors, including IGFBPs, that exert extracellular and intracellular functions in IGF-dependent or independent manner.In this report, we investigated the expression and function of IGFBP2 in senescent keratinocytes isolated from the skin of patients with plaque psoriasis. We found that IGFBP2 is aberrantly expressed and released by these cells in vivo, as well as in vitro in keratinocyte cultures undergoing progressive senescence, and it associates with the cyclin-dependent kinase inhibitors p21 and p16 expression. For the first time, we provide evidence for a dual action of IGFBP2 in psoriatic keratinocytes during growth and senescence processes. While extracellular IGFBP2 counter-regulates IGF-induced keratinocyte hyper-proliferation, intracellular IGFBP2 inhibits apoptosis by interacting with p21 and protecting it from ubiquitin-dependent degradation. Indeed, we found that cytoplasmic p21 sustains anti-apoptotic processes, by inhibiting pro-caspase 3 cleavage and JNK phosphorylation in senescent psoriatic keratinocytes. As a consequence, abrogation of p21, as well as that of IGFBP2, found to stabilize cytoplasmic p21 levels, lead to the restoration of apoptosis mechanisms in psoriatic keratinocytes, commonly observed in healthy cells.

The Brain-Skin Connection and the Pathogenesis of Psoriasis: A Review with a Focus on the Serotonergic System.

Psoriasis is a common non-communicable chronic immune-mediated skin disease, affecting approximately 125 million people in the world. Its pathogenesis results from a combination of genetic and environmental factors. The pathogenesis of psoriasis seems to be driven by the interaction between innate immune cells, adaptive immune cells and keratinocytes, in a process mediated by cytokines (including interleukins (IL)-6, IL-17 and IL-22, interferon and tumor necrosis factor) and other signaling molecules. This leads to an inflammatory process with increased proliferation of epidermal cells, neo-angiogenesis and infiltration of dendritic cells in the skin. Dysfunctional de novo glucocorticoid synthesis in psoriatic keratinocytes and the skin microbiome have also been suggested as mediators in the pathogenesis of this disease. To understand psoriasis, it is essential to comprehend the processes underlying the skin immunity and neuroendocrinology. This review paper focuses on the skin as a neuroendocrine organ and summarizes what is known about the skin immune system, the brain–skin connection and the role played by the serotonergic system in skin. Subsequently, the alterations of neuroimmune processes and of the serotonergic system in psoriatic skin are discussed, as well as, briefly, the genetic basis of psoriasis.

Cannabidiol Effects on Phospholipid Metabolism in Keratinocytes from Patients with Psoriasis Vulgaris.

Psoriasis is a chronic inflammatory skin disease characterized by dysregulated keratinocyte differentiation, but oxidative stress also plays an important role in the pathogenesis of this disease. Here, we examined the effect of cannabidiol (CBD), a phytocannabinoid with antioxidant and anti-inflammatory properties, on the redox balance and phospholipid metabolism in UVA/UVB-irradiated keratinocytes isolated from the skin of psoriatic patients or healthy volunteers. CBD accumulates mainly in membrane keratinocytes, especially from patients with psoriasis. This phytocannabinoid reduces the redox imbalance observed in the UV-irradiated keratinocytes of healthy subjects. It does so by decreasing reactive oxygen species (ROS) generation, increasing the Trx-dependent system efficiency, and increasing vitamin A and E levels. Consequently, a reduction in lipid peroxidation products, such as 8-isoprostanes and 4-hydroxynonenal, was also observed. Moreover, CBD modifies redox balance and lipid peroxidation in psoriatic patient keratinocytes following UV-irradiation. Interestingly, these changes are largely in the opposite direction to the case of keratinocytes from healthy subjects. CBD also regulates metabolic changes by modulating the endocannabinoid system that is disturbed by psoriasis development and UV irradiation. We observed a decrease in anandamide level in the UV-irradiated keratinocytes of healthy controls following CBD treatment, while in keratinocytes from patients treated with CBD, anandamide level was increased. However, the level of palmitoylethanolamide (PEA) was decreased in both groups treated with CBD. We further demonstrate that CBD increases CB1 receptor expression, primarily in the keratinocytes of patients, and increases CB2 receptor expression in both the psoriatic and control groups. However, CBD decreases CB2 receptor expression in UV-irradiated keratinocytes taken from patients. The UV- and psoriasis-induced activity of transmembrane transporters (Multidrug-Resistance (MDR) and breast cancer resistance protein (BCRP)) is normalized after CBD treatment. We conclude that CBD partially reduces oxidative stress in the keratinocytes of healthy individuals, while showing a tendency to increase the oxidative and inflammatory state in the keratinocytes of patients with psoriasis, especially following UV-irradiation.

Methotrexate use and NAD+/NADH metabolism in psoriatic keratinocytes.

Methotrexate inhibits tetrahydrofolic acid production and influences mitochondrial oxygen uptake and activity of several enzymes in the respiratory chain reactions, which utilize nicotinamide adenine dinucleotide-linked (NAD-linked) substrates. Hyperproliferation of keratinocytes in psoriasis requires oxidative phosphorylation, in which the reduced form of nicotinamide adenine dinucleotide (NADH) is an electron donor. One hypothesis links increased cellular metabolism to the increased NADH/NAD+ ratio; as expected, the topical application of NAD+ (oxidized form of nicotinamide-adenine dinucleotide) resulted in a clinical improvement of psoriatic lesions in one study. Nevertheless, another report revealed reduced fluorescence of NADH in psoriatic plaques. The biological activity of NADH is not limited only to serving as the electron donor. It was also found to regulate gene transcription.

Endoplasmic reticulum stress links psoriasis vulgaris with keratinocyte inflammation.

IntroductionEndoplasmic reticulum stress (ERS) has been implicated in the pathogenesis of various inflammatory diseases. However, the role of ERS in psoriasis is still unclear.AimTo examine ERS in psoriasis keratinocytes and to assess the association of ERS with skin inflammation response.Material and methodsWe investigated ERS in keratinocytes of normal skin, lesional and perilesional psoriasis vulgaris (PV) skin tissues using transmission electron microscope (TEM) examination, Western blot and immunostaining analysis.ResultsBy TEM examination, we found that endoplasmic reticulum (ER) in psoriatic keratinocytes was ultrastructurally abnormal, with changes in ER morphology and the ER expansion. Using Western blot and immunostaining analysis, we showed that the expression of ERS-associated proteins, such as BiP, CHOP and XBP1, was enhanced in PV epidermis compared to the healthy skin. Moreover, abundant TNF-α protein was correlated to the increased BiP, CHOP and XBP1 expression in PV epidermis.ConclusionsOur findings demonstrate that PV keratinocytes have an increased ERS, which may contribute to the pathogenesis of PV.

Effect of methotrexate treatment on the expression of epidermal-fatty acid-binding protein (E-FABP) and apolipoproteins in patients with psoriasis.

IntroductionEpidermal-fatty acid-binding protein (E-FABP) is a marker of transiently amplifying cells which are formed from stem cells in epidermis. Their role is an uptake of fatty acids and metabolism. Psoriatic keratinocytes overexpress E-FABPs, which leads to acanthosis and may explain the lipid’s disturbances in psoriasis.AimAssessment of FABP and apolipoprotein expression in patients treated with methotrexate (MTX).Material and methodsFABP expression in the lesional and perilesional psoriatic skin from 11 male patients compared to 5 healthy skin samples were evaluated by immunohistochemistry. FABP, apolipoprotein A1 (ApoA1) and B (ApoB) serum levels were assessed by ELISA. These parameters were evaluated before and after treatment with subcutaneous MTX (15 mg/wk for 12 weeks).ResultsExpression of E-FABP was lower in the control group than in the lesional and perilesional psoriatic skin, before and after treatment. After treatment the expression decreased in the lesional and perilesional skin. Serum E-FABP was higher in the control group (482.855 ±240.550 pg/ml) compared to patients, but not statistically significantly. After MTX treatment, a statistically significant reduction was observed in psoriatic patients. ApoA1 levels did not differ in the control and patients groups, both before and after treatment. In contrast, ApoB levels did not differ statistically between the control group (1447.126 ±311.11 ng/ml) and patients before treatment, while they were the lowest after treatment (1081.67 ±117.83 ng/ml vs. 808.306 ±103.72 ng/ml; p < 0.01).ConclusionsOur study confirms the beneficial effect of MTX, not only as an anti-proliferative effect, but also reducing the cardiovascular risk by decreasing atherogenic ApoB.

Keratinocyte exosomes activate neutrophils and enhance skin inflammation in psoriasis.

Psoriasis is a chronic inflammatory skin disease that severely affects patients physiologically and psychologically. The pathogenesis involving communication between psoriatic keratinocytes and infiltrated immune cells such as neutrophils remains unclear. Exosomes are emerging mediators of intercellular communication. Herein we aim to investigate the release and function of psoriatic keratinocyte exosomes, which have not been illustrated to any extent. We first isolated exosomes from both healthy and psoriasis-like keratinocytes treated with psoriatic cytokine cocktail. These exosomes were observed to be endocytosed by neutrophils. Unlike non-cytokine-treated keratinocyte exosomes, cytokine-treated keratinocyte exosomes significantly induced NETosis (the process by which neutrophils produce and release neutrophil extracellular traps) and the expressions of IL-6, IL-8, and TNF-α in neutrophils. Proteomic analysis showed that cytokine-treated keratinocyte exosomes exhibited a specific protein profile with proteins enriched in immune-related pathways. We then confirmed that NF-κB and p38 MAPK signaling pathways were activated in neutrophils stimulated by cytokine-treated keratinocyte exosomes and were responsible for the expressions of proinflammatory factors mentioned above. Finally, we verified in vivo that cytokine-treated keratinocyte exosomes participated in the skin lesion development of imiquimod-induced psoriasis-like mouse model. Collectively, we reveal that the release of exosomes works as a way of keratinocyte-neutrophil communication, indicating that keratinocyte exosomes, with their specific cargoes, are therapeutic candidates for psoriasis.-Jiang, M., Fang, H., Shao, S., Dang, E., Zhang, J., Qiao, P., Yang, A., Wang, G. Keratinocyte exosomes activate neutrophils and enhance skin inflammation in psoriasis.

325 E3 ligase Trim21 ubiquitylates NF-κB p65 subunit and promotes inflammation in psoriatic keratinocytes

Skin inflammation, a hallmark of psoriasis, has been the focus of study for many years. Tripartite motif-containing protein 21 (Trim21), which is an E3 ligase, is involved in mediating the inflammatory process and participates in the pathogenesis of various autoimmune diseases. We previously noticed that the expression of Trim21, which showed a significant 2. 6 ±0. 5 fold increase in mRNA level as well as an almost 3-fold increase in protein level (p<0. 05) in psoriasis epidermis as compared with normal skin, was markedly upregulated in psoriatic epidermis. Moreover, we proved that Trim21 was the main E3 ligase responsible for the ubiquitination of a marker of hyperproliferation-Keratin 17, which regulated its stability and its interaction with STAT3 in psoriatic keratinocytes. However, its role in mediating the inflammation, especially in keratinocytes, has not been elucidated. Herein, we illustrated a previously unrecognized role for Trim21 in promoting inflammation in keratinocytes, represented by stimulating the release of psoriasis-related cytokines and chemokines CXCL9-11, CCL20, IL-23 and IFN-γ. By screening a myriad of inflammation-related signaling pathways, we clarified that knockdown of Trim21 inhibited the activation of NF-κB and STAT3 pathways. Importantly, by immunoprecipitation combined with in vitro ubiquitination assays, we found that Trim21 interacted with and ubiquitylated p65 subunit of NF-κB, which further enhanced p65 phosphorylation and activation by IKK, initiating expression of the aforementioned downstream cytokines and chemokines. Lastly, in vivo studies showed that knockdown of Trim21 had a satisfactory effect in alleviating the imiquimod (IMQ)-induced psoriasiform lesions. Our present study uncovers a pivotal role of Trim21 in promoting inflammation in psoriatic keratinocytes, which might contribute to the pathogenesis of psoriasis. Thus, Trim21 might be a potential target for the treatment of psoriasis.

Next-Generation Sequencing Identifies the Keratinocyte-Specific miRNA Signature of Psoriasis

Next-Generation Sequencing Identifies the Keratinocyte-Specific miRNA Signature of Psoriasis

375 The chromatin architectural protein CTCF regulates expression of pro-inflammatory cytokines in the skin cells

Increased evidence suggests that alterations in chromatin structure result in aberrant pro-inflammatory cytokines expression that leads to prolonged inflammatory responses. CCCTC-binding factor (CTCF) is a transcriptional repressor that insulates the expression of neighbouring genes and is involved in chromatin interactions between distal and proximal gene regulatory elements. However, the role of CTCF in the control of pro-inflammatory cytokines expression in the skin cells remains unknown. Here, we show that CTCF is expressed in the nuclei of normal human epidermal keratinocytes (NHEK) and dermal fibroblasts (DF), while its siRNA-mediated deficiency induces cell-type specific changes in pro-inflammatory gene expression. Knockdown of CTCF using siRNAs leads to significant reductions in the transcription of a number of pro-inflammatory genes (TNF, IL1B, IL12B, IL17A, IL19, IL23A, IL36A, CXCL8) in NHEK. In contrast, transcript levels of these genes were markedly up-regulated in CTCF-depleted DF. Furthermore, TNF-alpha treatment causes a more profound inhibitory effect on the CTCF expression in DF compared to NHEK. Finally, we show that CTCF is down-regulated in primary psoriatic fibroblasts compared to DF, while CTCF expression was not affected in psoriatic keratinocytes. Taken together, these data suggest that the chromatin architectural protein CTCF is involved in cell-type specific regulation of pro-inflammatory genes in the skin cells, which suggests its involvement in pathogenesis of inflammatory skin diseases such as psoriasis.

292 IL-17 and IL-22 promote keratinocyte stemness in the germinative compartment in psoriasis

Psoriasis is widely regarded as an inflammatory T-cell-mediated disorder, where the hyperproliferation and disturbed maturation of the keratinocytes (KCs) are believed to be driven by Th1- and Th17-associated cytokines and chemokines. Although recent genetic advances suggest that both immune and epidermal components contribute to disease susceptibility, the role of KCs in the formation of the psoriatic lesion has received less attention. We applied flow cytometry on KCs from lesional and non-lesional epidermis and observed an overall increase in the expression of established stemness markers. We found a reduced percentage of cells positive for the early differentiation marker, cytokeratin 10 (K10), while the upregulation of stemness markers was more pronounced in the K10+ cells. We hypothesized that stimuli present in the psoriatic microenvironment would be a contributing cause for the cellular immaturity. Indeed, treatment with IL-17 and IL-22 induced a similar expression pattern of stem cell markers in normal KCs with increase in CD44, p63 and CD29 and a decrease in K10. Furthermore, IL-17 and IL-22 increased the colony-forming efficiency and long-term proliferative capacity, reflecting increased stem cell-like characteristics in the KC population. Like the reduced size observed in the lesion-derived psoriatic KCs, the size of the KCs decreased after treatment with IL-17 and IL-22. Moreover, when compared with normal KCs seeded at colony density for 10 days, psoriatic KCs formed a strikingly larger number of colonies of larger size. These data suggest that IL-17 and IL-22 link the inflammatory response to the immature differentiation and epithelial regeneration by acting directly on KCs to promote cell stemness.

079 The role and mechanism of LPA in dysfunction of psoriatic keratinocytes

079 The role and mechanism of LPA in dysfunction of psoriatic keratinocytes

The Keratinocyte Transcriptome in Psoriasis: Pathways Related to Immune Responses, Cell Cycle and Keratinization

Psoriasis is a common immune-mediated disease resulting from altered cross-talk between keratinocytes and immune cells. Previous transcriptomic studies have identified thousands of deregulated genes in psoriasis skin; however, the transcriptomic changes confined to the epidermal compartment remained poorly characterized. The aim of this study was to characterize the transcriptomic landscape of psoriatic keratinocytes, using sorted CD45neg epidermal cells. Genes with functions in innate immunity, type I interferon response, cell cycle and keratinization were enriched among deregulated genes in psoriatic keratinocytes. Gene set enrichment analysis indicated the dominance of interleukin (IL)-22/IL-17A signatures in the epidermal psoriasis-signature. A set of deregulated genes overlapped with psoriasis-associated genetic regions, suggesting that genetic variations affecting gene expression in keratinocytes contribute to susceptibility to psoriasis. Several psoriasis-susceptibility genes, which were previously believed to be expressed preferentially or exclusively in immune cells, were identified as having altered expression in psoriatic keratinocytes. These results highlight the role of keratinocytes in the pathogenesis of psoriasis, and indicate that both genetic factors and an inflammatory microenvironment contribute to epidermal alterations in psoriasis.

Therapeutic Effects of Synthetic Antimicrobial Peptides, TRAIL and NRP1 Blocking Peptides in Psoriatic Keratinocytes.

Psoriasis is a chronic, recurrent, heterogeneous, cutaneous inflammatory skin disease for which there is no cure. It affects approximately 7.5 million people in the United States. Currently, several biologic agents that target different molecules implicated in the pathogenic processes of psoriasis are being assessed in diverse clinical studies. However, relapse usually occurs within weeks or months, meaning there is currently no cure for psoriasis. Therefore, recent studies have discovered diverse new potential treatments for psoriasis: inhibitors of bacteria such as Staphylococcus aureus, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and neuropilin 1 (NRP1). A promising approach that has recently been described involves modifying antimicrobial peptides to develop new cutaneous anti-bacterial agents that target inflammatory skin disease induced by Staphylococcus. Increased expression of TRAIL and its death receptors DR4 and DR5 has been implicated in the pathogenesis of plaque psoriasis. In addition, TRAIL has the ability to inhibit angiogenesis by inducing endothelial cell death and by negative regulation of VEGF-induced angiogenesis via caspase-8-mediated enzymatic and non-enzymatic functions. Since NRP1 regulates angiogenesis induced by multiple signals, including VEGF, ECM and semaphorins, and also initiates proliferation of keratinocytes through NF-κB signaling pathway in involved psoriatic skin, targeting NRP1 pathways may offer numerous windows for intervention in psoriasis. In this review, we will focus on the current knowledge about the emerging role of synthetic antimicrobial peptides, TRAIL and NRP1 blocking peptides in the pathogenesis and treatment of psoriasis.

Contribution of Immunohistochemistry in Revealing S100A7/JAB1 Colocalization in Psoriatic Epidermal Keratinocyte.

The application of immunohistological methods provides an invaluable contribution in revealing the protein colocalization, which may reflect the occurrence of molecular interaction processes.This chapter describes comprehensive protocols for detection of S100A7/JAB1 colocalization by immunohistochemistry in archival formalin-fixed and paraffin-embedded skin biopsies from healthy and psoriatic subjects. In addition, we provide a protocol for immunocytochemical detection of S100A7/JAB1 colocalization in S100A7 CRISPR-activated human keratinocyte cell line.

Membrane-enriched solute carrier family 2 member 1 (SLC2A1/GLUT1) in psoriatic keratinocytes confers sensitivity to 2-deoxy-D-glucose (2-DG) treatment.

Psoriasis is a common chronic disease with accelerated epidermal cell growth. Solute carrier family 2 member 1 (SLC2A1), also named GLUT1, transports glucose and its analogues into cells. With elevated membrane-bound GLUT1, psoriatic keratinocytes uptake more glucose with increased glucose metabolism. Competition between glucose and its analogues can serve as a strategy to inhibit glycolysis as well as proliferation. In this study, we investigated the expression patterns of GLUT1 in keratinocytes in the human psoriasis vulgaris and imiquimod-induced psoriasis model, and determined that the glucose metabolism inhibitor 2-deoxy-D-glucose (2-DG) can relieve the psoriatic lesions. We found membrane-enriched GLUT1 in psoriasis keratinocytes, which suggested some potential for glucose metabolic target therapy based on the glycolytic microenvironment. Furthermore, 2-DG was able to relieve the psoriatic lesions in an in vivo animal model which provides a new possible therapeutic strategy.

The lipoxygenase‐hepoxilin pathway is activated in cutaneous plaque lesions of psoriasis

AbstractPsoriasis is a common skin disorder that is characterized by hyperkeratosis, epidermal hyperplasia, T‐cell and neutrophil recruitment, and changes in the vascular endothelial system. The several upregulated variable lipid mediators, including the eicosanoids, in psoriatic keratinocytes were described previously, although some results were contradictory. Since hepoxilin is less stable than other eicosanoids such as hydroxyeicosatetraenoic acid (HETE), the measurement of hepoxilin is difficult. In this study, to clarify the relationship between hepoxilin/hepoxilin‐related fatty acid derivatives and psoriasis vulgaris, we evaluated the amount of production of lipid mediators including hepoxilins in skin tissues of patients with psoriasis vulgaris in comparison with normal controls by high‐performance liquid chromatography/mass spectrometry. Most of the hepoxilins and related lipids evaluated in this study tended to be more abundant in the lesional skin from the psoriasis patient group (PPG) than in the skin from controls. Interestingly, 12R‐HETE was markedly higher in the skin samples from the PPG. In addition, the lipids produced in the lipoxygenase pathway, including hepoxilin, were elevated in the skin lesions of the PPG compared with those of normal controls, whereas the lipids produced in the cyclooxygenase pathway were decreased in the skin lesions from the PPG. Our results suggest that an imbalance between the lipoxygenase and cyclooxygenase pathways may contribute to psoriatic pathomechanisms.

Epidermal mTORC1 Signaling Contributes to the Pathogenesis of Psoriasis and Could Serve as a Therapeutic Target.

Although modern biologics targeting different inflammatory mediators show promising therapeutic success, comprehensive knowledge about the molecular events in psoriatic keratinocytes that contribute to the pathogenesis and could serve as therapeutic targets is still scarce. However, recent efforts to understand the deregulated signal transduction pathways have led to the development of small molecule inhibitors e.g., tofacitinib targeting the Jak/Stat cascade that opens additional therapeutic options. Recently, the PI3-K/Akt/mTOR signaling pathway has emerged as an important player in the control of epidermal homeostasis. This review summarizes the current knowledge on the role of this pathway in the pathogenesis of psoriasis, especially the epidermal manifestation of the disease and discusses current approaches to target the pathway therapeutically.

Selective Immunomodulation of Inflammatory Pathways in Keratinocytes by the Janus Kinase (JAK) Inhibitor Tofacitinib: Implications for the Employment of JAK-Targeting Drugs in Psoriasis.

IFN-γ and IL-22 are deeply involved in the pathogenesis of psoriasis, as they boost the expression of inflammatory genes and alter proliferative and differentiative programs in keratinocytes. The JAK1/JAK2/STAT1 and JAK1/TYK2/STAT3 pathways triggered by IFN-γ and IL-22, respectively, are aberrantly activated in psoriasis, as highlighted by the peculiar STAT1 and STAT3 signatures in psoriatic skin lesions. To limit the detrimental consequences of IFN-γ and IL-22 excessive stimulation, psoriatic keratinocytes activate suppressor of cytokine signaling (SOCS)1 and SOCS3, which in turn dampen molecular signaling by inhibiting JAK1 and JAK2. Thus, JAK targeting appears to be a reasonable strategy to treat psoriasis. Tofacitinib is an inhibitor of JAK proteins, which, similarly to SOCS, impedes JAK phosphorylation. In this study, we evaluated the immunomodulatory effects of tofacitinib on epidermal keratinocytes in in vitro and in vivo models of psoriasis. We demonstrated the selectivity of tofacitinib inhibitory action on IFN-γ and IL-22, but not on TNF-γ or IL-17 proinflammatory signaling, with suppressed expression of IFN-γ-dependent inflammatory genes, and restoration of normal proliferative and differentiative programs altered by IL-22 in psoriatic keratinocyte cultures. Tofacitinib also potently reduced the psoriasiform phenotype in the imiquimod-induced murine model of psoriasis. Finally, we found that tofacitinib mimics SOCS1 or SOCS3 activities, as it impaired the same molecular pathways in IFN-γ or IL-22-activated keratinocytes.