STAT3-dependent effects of IL-22 in human keratinocytes are counterregulated by sirtuin 1 through a direct inhibition of STAT3 acetylation

Prevalence and trends of contact sensitization in patients with psoriasis in Lithuania

Background

Psoriasis and allergic contact dermatitis are 2 very common dermatoses. The relationship between them has not yet been fully understood. Contact dermatitis can be an additional cause of epidermal disruption in psoriasis patients, resulting in poor management of the disease.

Objective

To analyze the tendencies of contact sensitization in a cohort of psoriasis patients with suspected allergic contact dermatitis.

Methods

Psoriasis patients (n = 85) with suspected contact dermatitis underwent patch testing with European Baseline allergen series S-1000 in Vilnius University Hospital Santaros Klinikos Centre of Dermatovenereology from August 2020 to August 2021. Their results are presented in this study.

Results

The patch test was positive in 43.5% (n = 37) of patients. Contact sensitization was more prevalent in patients with mild psoriasis, as characterized by Psoriasis Area Surface Index scores ≤10, compared to those with moderate-to-severe psoriasis (P < .05). Generalized psoriasis and nail involvement were more common among nonsensitized patients (P < .05). Most common contact allergens among sensitized patients were nickel (II) sulfate, formaldehyde, and potassium dichromate.

Conclusion

An inverse trend was observed between psoriasis severity and contact sensitization. Extended psoriatic involvement was uncommon in sensitized patients.

Histone modification in psoriasis: Molecular mechanisms and potential therapeutic targets

Psoriasis is an immune-mediated, inflammatory disease. Genetic and environmental elements are involved in the nosogenesis of this illness. Epigenetic inheritance serves as the connection between genetic and environmental factors. Histone modification, an epigenetic regulatory mechanism, is implicated in the development of numerous diseases. The basic function of histone modification is to regulate cellular functions by modifying gene expression. Modulation of histone modification, such as regulation of enzymes pertinent to histone modification, can be an alternative approach for treating some diseases, including psoriasis. Herein, we reviewed the regulatory mechanisms and biological effects of histone modifications and their roles in the pathogenesis of psoriasis.

The role of deacetylase SIRT1 in allergic diseases

The silent information regulator sirtuin 1 (SIRT1) protein is an NAD+-dependent class-III lysine deacetylase that serves as an important post-transcriptional modifier targeting lysine acetylation sites to mediate deacetylation modifications of histones and non-histone proteins. SIRT1 has been reported to be involved in several physiological or pathological processes such as aging, inflammation, immune responses, oxidative stress and allergic diseases. In this review, we summarized the regulatory roles of SIRT1 during allergic disorder progression. Furthermore, we highlight the therapeutic effects of targeting SIRT1 in allergic diseases.

Punicalagin from pomegranate ameliorates TNF-α/IFN-γ-induced inflammatory responses in HaCaT cells via regulation of SIRT1/STAT3 axis and Nrf2/HO-1 signaling pathway

Punicalagin (PUN) was isolated from the peel of pomegranate (Punica granatum L.), is a polyphenol with anti-inflammatory, hepatoprotective, and antioxidant activities. However, it remains unclear whether PUN alleviates the inflammation and anti-inflammatory mechanisms in pro-inflammatory cytokines-induced human keratinocyte HaCaT cells. Here, we investigated that tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) mixture-stimulated HaCaT cells were treated with various concentrations of PUN, followed by analyzed the expression of inflammation-related mediators and evaluate anti-inflammatory-related pathways. Our results demonstrated that PUN ≤ 100 μM did not reduce HaCaT cell viability, and PUN ≥ 3 μM was sufficient to decrease interleukin-6 (IL-6), IL-8, monocyte chemoattractant protein-1 (MCP-1), chemokine ligand 5 (CCL5), CCL17 and CCL20 concentrations. We found that PUN ≥ 10 μM and ≥ 3 μM significantly increased sirtuin 1 (SIRT1) expression and inhibited signal transducer and activator of transcription 3 (STAT3) phosphorylation, respectively. PUN downregulated inflammation-related proteins cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), enhanced nuclear factor erythroid-2-related factor-2 (Nrf2) and heme oxygenase-1 (HO-1) expression. Moreover, PUN decreased intercellular adhesion molecule-1 (ICAM-1) expression and inhibited monocyte adhesion to inflamed HaCaT cells. PUN also suppressed inflammatory-related pathways, including mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways in TNF-α/IFN-γ- stimulated HaCat cells. Collectively, there is significant evidence that PUN has effective protective defenses against TNF-α/IFN-γ-induced skin inflammation by enhancing SIRT1 to mediate STAT3 and Nrf2/HO-1 signaling pathway.

Dysregulation of histone deacetylases in ocular diseases

Ocular diseases are a growing global concern and have a significant impact on the quality of life. Cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy are the most prevalent ocular diseases. Their prevalence and the global market size are also increasing. However, the available pharmacotherapy is currently limited. These diseases share common pathophysiological features, including neovascularization, inflammation, and/or neurodegeneration. Histone deacetylases (HDACs) are a class of enzymes that catalyze the removal of acetyl groups from lysine residues of histone and nonhistone proteins. HDACs are crucial for regulating various cellular processes, such as gene expression, protein stability, localization, and function. They have also been studied in various research fields, including cancer, inflammatory diseases, neurological disorders, and vascular diseases. Our study aimed to investigate the relationship between HDACs and ocular diseases, to identify a new strategy for pharmacotherapy. This review article explores the role of HDACs in ocular diseases, specifically focusing on diabetic retinopathy, age-related macular degeneration, and retinopathy of prematurity, as well as optic nerve disorders, such as glaucoma and optic neuropathy. Additionally, we explore the interplay between HDACs and key regulators of fibrosis and angiogenesis, such as TGF-β and VEGF, highlighting the potential of targeting HDAC as novel therapeutic strategies for ocular diseases.

Obesity and prostate cancer - microenvironmental roles of adipose tissue

Obesity is known to have important roles in driving prostate cancer aggressiveness and increased mortality. Multiple mechanisms have been postulated for these clinical observations, including effects of diet and lifestyle, systemic changes in energy balance and hormonal regulation and activation of signalling by growth factors and cytokines and other components of the immune system. Over the past decade, research on obesity has shifted towards investigating the role of peri-prostatic white adipose tissue as an important source of locally produced factors that stimulate prostate cancer progression. Cells that comprise white adipose tissue, the adipocytes and their progenitor adipose stromal cells (ASCs), which proliferate to accommodate white adipose tissue expansion in obesity, have been identified as important drivers of obesity-associated cancer progression. Accumulating evidence suggests that adipocytes are a source of lipids that are used by adjacent prostate cancer cells. However, results of preclinical studies indicate that ASCs promote tumour growth by remodelling extracellular matrix and supporting neovascularization, contributing to the recruitment of immunosuppressive cells, and inducing epithelial-mesenchymal transition through paracrine signalling. Because epithelial-mesenchymal transition is associated with cancer chemotherapy resistance and metastasis, ASCs are considered to be potential targets of therapies that could be developed to suppress cancer aggressiveness in patients with obesity.

Vinpocetine alleviates intestinal ischemia/reperfusion injury and enhances M2 macrophage polarization in rats: Role of SIRT1/SOCS3/STAT3 signaling pathway

Vinpocetine (Vinpo) is a neuroprotective vasodilator drug. It is an effective therapeutic agent for a variety of cerebrovascular and cognitive disorders. However, its potential protective efficacy on intestinal ischemia/reperfusion (I/R) injury remains elusive. The present study aimed to investigate the effect of Vinpo on intestinal I/R injury and to explore its modulatory effect on sirtuin (SIRT1)/ Suppressor of cytokine signaling (SOCS3)/ Signal Transducer and Activator of Transcription (STAT3) signaling. Twenty-four male Wistar albino rats were randomly allocated into four groups. G1 (sham): rats were subjected to surgical stress without I/R, GII (I/R): rats were subjected to 60 min/2-h I/R, GIII (Vinpo + I/R): rats were pre-treated with Vinpo (20 mg/kg/day, P.O. daily) for 2 weeks before intestinal I/R; GIV (EX527 + Vinpo + I/R): rats received both Vinpo (20 mg/kg/day, P.O.) and EX527 (5 mg/kg, once every 2 days, i.p) for 2 weeks before intestinal I/R. The current results showed that Vinpo improved the intestinal histopathological picture, enhanced M1 to M2 macrophage polarization and alleviated the I/R-induced increase in interleukins (IL-6, IL-1β), tumor necrosis factor (TNF-α), inducible nitric oxide synthase (i-NOS), and nitric oxide (NO). Additionally, Vinpo pretreatment upregulated SIRT1 mRNA expression/protein level and SOCS3 mRNA expression while downregulating P-STAT3 immunoreactivity. The effects of Vinpo were attenuated by the SIRT1 inhibitor EX527. We concluded that Vinpo ameliorated the intestinal I/R injury and enhanced M2 anti-inflammatory macrophage polarization through modulation of SIRT1/SOCS3/STAT3/i-NOS cascade.

The Role of Sirtuins in the Pathogenesis of Psoriasis

Psoriasis is the most common chronic inflammatory skin disease with a genetic basis. It is characterised by keratinocyte hyperproliferation, parakeratosis and inflammatory cell infiltration. Psoriasis negatively affects a patient's physical and emotional quality of life. Sirtuins (SIRTs; silent information regulators) are an evolutionarily conserved group of enzymes involved in the post-translational modification of proteins, including deacetylation, polyADP-ribosylation, demalonylation and lipoamidation. SIRTs are involved in a number of cellular pathways related to ageing, inflammation, oxidative stress, epigenetics, tumorigenesis, the cell cycle, DNA repair and cell proliferation, positioning them as an essential component in the pathogenesis of many diseases, including psoriasis. Activation of SIRT1 counteracts oxidative-stress-induced damage by inhibiting the mitogen-activated protein kinases (MAPK), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription 3 (STAT3) pathways and may mitigate pathological events in psoriasis. There is a significant reduction in the expression of SIRT1, SIRT2, SIRT3, SIRT4 and SIRT5 and an increase in the expression of SIRT6 and SIRT7 in psoriasis. The aim of the review is to draw the attention of physicians and scientists to the importance of SIRTs in dermatology and to provide a basis and impetus for future discussions, research and pharmacological discoveries to modulate SIRT activity. In light of the analysis of the mode of action of SIRTs in psoriasis, SIRT1-SIRT5 agonists and SIRT6 and SIRT7 inhibitors may represent new therapeutic options for the treatment of psoriasis.

Interleukin-22 promotes the proliferation and migration of hepatocellular carcinoma cells via the phosphoinositide 3-kinase (PI3K/AKT) signaling pathway

BACKGROUND

Interleukin-22 (IL-22) is a pro-inflammatory cytokine released during the immune response in chronic liver injury. Although IL-22 mediates tissue regeneration, its uncontrolled production may generate a carcinogenic environment resulting in hepatocellular carcinoma (HCC). This study aims to identify the effect of IL-22 on anti-apoptotic and metastatic genes and the molecular pathways responsible for IL-22-mediated hepatic carcinogenesis.

METHODS AND RESULTS

Three cancerous liver lines, HepG2, SNU-387, Huh7, and one normal liver line, THLE2, were treated with IL-22. RT-qPCR analysis was conducted to study the role of IL-22 in altering the expression levels of anti-apoptotic genes, MCL-1 and BCL-2, and metastatic genes, MMP-7 and MMP-9. A significant increase in expression levels of these genes was observed after IL-22 treatment. Furthermore, to explore the major pathways involved in IL-22-mediated upregulation of anti-apoptotic and metastatic genes, cells were treated with inhibitors of JAK/STAT and PI3K/AKT pathways along with IL-22. Resultantly, a significant decrease in expression levels of target genes was observed, indicating the involvement of JAK/STAT and PI3K/AKT signaling cascades in IL-22-mediated oncogenesis. Finally, Cell Scratch assay was performed to check the effect of IL-22 and inhibitors of JAK/STAT and PI3K/AKT on the metastatic potential of liver cells. While migration was observed in Huh7 and THLE2 cells treated with IL-22, no migration was observed in cells treated with IL-22 along with JAK/STAT and PI3K/AKT inhibitors. Results indicate that IL-22 encourages metastasis in HCC cells via the JAK/STAT and PI3K/AKT pathways.

CONCLUSION

Results showed that IL-22 upregulates anti-apoptotic and metastatic genes in HCC through JAK/STAT and PI3K/AKT signaling pathways.

Proteomic and Metabolomic Changes in Psoriasis Preclinical and Clinical Aspects

Skin diseases such as psoriasis (Ps) and psoriatic arthritis (PsA) are immune-mediated inflammatory diseases. Overlap of autoinflammatory and autoimmune conditions hinders diagnoses and identifying personalized patient treatments due to different psoriasis subtypes and the lack of verified biomarkers. Recently, proteomics and metabolomics have been intensively investigated in a broad range of skin diseases with the main purpose of identifying proteins and small molecules involved in the pathogenesis and development of the disease. This review discusses proteomics and metabolomics strategies and their utility in research and clinical practice in psoriasis and psoriasis arthritis. We summarize the studies, from in vivo models conducted on animals through academic research to clinical trials, and highlight their contribution to the discovery of biomarkers and targets for biological drugs.

The Role of Adipokines in the Pathogenesis of Psoriasis

Psoriasis is a chronic and immune-mediated skin condition characterized by pro-inflammatory cytokines and keratinocyte hyperproliferation. Dendritic cells, T lymphocytes, and keratinocytes represent the main cell subtypes involved in the pathogenesis of psoriasis, while the interleukin-23 (IL-23)/IL-17 pathway enhances the disease progression. Human adipose tissue is an endocrine organ, which secretes multiple proteins, known as adipokines, such as adiponectin, leptin, visfatin, or resistin. Current evidence highlights the immunomodulatory roles of adipokines, which may contribute to the progression or suppression of psoriasis. A better understanding of the complexity of psoriasis pathophysiology linked with adipokines could result in developing novel diagnostic or therapeutic strategies. This review aims to present the pathogenesis of psoriasis and the roles of adipokines in this process.

Pathogenesis, multi-omics research, and clinical treatment of psoriasis

Psoriasis is a common inflammatory skin disease involving interactions between keratinocytes and immune cells that significantly affects the quality of life. It is characterized by hyperproliferation and abnormal differentiation of keratinocytes and excessive infiltration of immune cells in the dermis and epidermis. The immune mechanism underlying this disease has been elucidated in the past few years. Research shows that psoriasis is regulated by the complex interactions among immune cells, such as keratinocytes, dendritic cells, T lymphocytes, neutrophils, macrophages, natural killer cells, mast cells, and other immune cells. An increasing number of signaling pathways have been found to be involved in the pathogenesis of psoriasis, which has prompted the search for new treatment targets. In the past decades, studies on the pathogenesis of psoriasis have focused on the development of targeted and highly effective therapies. In this review, we have discussed the relationship between various types of immune cells and psoriasis and summarized the major signaling pathways involved in the pathogenesis of psoriasis, including the PI3K/AKT/mTOR, JAK-STAT, JNK, and WNT pathways. In addition, we have discussed the results of the latest omics research on psoriasis and the epigenetics of the disease, which provide insights regarding its pathogenesis and therapeutic prospects; we have also summarized its treatment strategies and observations of clinical trials. In this paper, the various aspects of psoriasis are described in detail, and the limitations of the current treatment methods are emphasized. It is necessary to improve and innovate treatment methods from the molecular level of pathogenesis, and further provide new ideas for the treatment and research of psoriasis.

Influence of narrow-band ultraviolet B therapy on sirtuin 1 expression in lesional skin of patients with chronic plaque psoriasis: Relation to clinical improvement and interferon-γ expression

BACKGROUND

Reduced sirtuin 1 (Sirt1) expression in psoriasis was previously reported, and its activation was associated with disease improvement. Narrow-band ultraviolet B (NB-UVB) downregulates several pro-inflammatory cytokines such as interferon-γ (IFN-γ) and influences keratinocyte differentiation in psoriasis.

OBJECTIVES

The aim of this study was to study the in vivo influence NB-UVB treatment on Sirt1 expression in psoriatic skin in relation to disease improvement and IFN-γ expression.

METHODS

Twenty-six patients with chronic plaque psoriasis were evaluated, and psoriasis area severity index (PASI) was calculated. Skin biopsies were taken from lesional skin of the patients before and after 3 months of treatment with NB-UVB and from 26 controls, where the distribution and immunohistochemistry (IHC) scores of Sirt1 and IFN-γ were determined.

RESULTS

After 3 months of treatment, Sirt1 distribution and epidermal IHC score were significantly higher, whereas Sirt1 dermal IHC score and IFN-γ distribution, epidermal and dermal IHC scores were significantly lower than the pre-treatment values. Before and after 3 months of NB-UVB therapy, PASI showed a significant negative correlation with Sirt1 distribution and epidermal IHC score; and a significant positive correlation with interferon-γ distribution and epidermal IHC score. Moreover, Sirt1 distributions were negatively correlated with the corresponding interferon-γ distributions. Conclusions The detected upregulation of epidermal Sirt1 following NB-UVB therapy possibly represents another mechanism by which NB-UVB can act in psoriasis and also highlights the role of Sirt1 upregulation in psoriasis treatment.

Role of Post-translational Modification of Silent Mating Type Information Regulator 2 Homolog 1 in Cancer and Other Disorders

Silent mating type information regulator 2 homolog 1 (SIRT1), an NAD⁺-dependent histone/protein deacetylase, has multifarious physiological roles in development, metabolic regulation, and stress response. Thus, its abnormal expression or malfunction is implicated in pathogenesis of various diseases. SIRT1 undergoes post-translational modifications, including phosphorylation, oxidation/reduction, carbonylation, nitrosylation, glycosylation, ubiquitination/deubiquitination, SUMOylation etc. which can modulate its catalytic activity, stability, subcellular localization, and also binding affinity for substrate proteins. This short review highlights the regulation of SIRT1 post-translational modifications and their pathophysiologic implications.

The Role of T Helper 22 Cells in Dermatological Disorders

T helper 22 (Th22) cells are a newly identified subset of CD4+ T cells that secrete the effector cytokine interleukin 22 (IL-22) upon specific antigen stimulation, barely with IFN-γ or IL-17. Increasing studies have demonstrated that Th22 cells and IL-22 play essential roles in skin barrier defense and skin disease pathogenesis since the IL-22 receptor is widely expressed in the skin, especially in keratinocytes. Herein, we reviewed the characterization, differentiation, and biological activities of Th22 cells and elucidated their roles in skin health and disease. We mainly focused on the intricate crosstalk between Th22 cells and keratinocytes and provided potential therapeutic strategies targeting the Th22/IL-22 signaling pathway.

Inverse correlation between the expression of AMPK/SIRT1 and NAMPT in psoriatic skin: A pilot study

PURPOSE

Epidermal hyperplasia and the involvement of immune cells characterize the clinical picture of psoriasis. Among the several factors involved, attention has been focused on sirtuin 1 (SIRT1) - a deacetylase endowed with a variety of functions including the control of metabolic and inflammatory processes-, and on nicotinamide phosphoribosyltransferase (NAMPT), important for SIRT1 activation and involved in inflammatory events. The aim of the study was to analyze changes of SIRT1 and NAMPT expression in psoriatic skin.

PATIENTS AND METHODS

Samples from healthy controls and psoriatic patients were subjected to immunohistochemical analysis.

RESULTS

A strong downregulation of SIRT1 expression was observed in skin samples from psoriatic patients compared to healthy controls. This was accompanied by a parallel reduction of adenosine monophosphate-activated kinase (AMPK) expression and, more strikingly, by the disappearance of cells immunolabeled for its active, phosphorylated form (pAMPK). In both cases, analysis of the distribution of immunopositive cells revealed a shift towards reduced intensity of staining. In contrast, NAMPT expression was upregulated in psoriatic samples in line with its pro-inflammatory role. This was again more visible with an intensity-based distribution analysis that evidenced a shift towards more intensely immunostained cell populations.

CONCLUSIONS

The present data correlate in the same samples the expression of SIRT1, pAMPK/AMPK and NAMPT in psoriasis and open the way for novel pharmacological targets in the treatment of the disease.

Long-Acting β2 Adrenergic Receptor Agonist Ameliorates Imiquimod-Induced Psoriasis-Like Skin Lesion by Regulating Keratinocyte Proliferation and Apoptosis

Psoriasis is a chronic inflammatory disease that affects approximately 1%–5% of the population worldwide. Considering frequent relapse, adverse drug reactions, and large costs of treatment, it is urgent to identify new medications for psoriasis. Keratinocytes play an essential role during psoriasis development, and they express high levels of β₂-Adrenergic receptor (β₂-AR), which increases intracellular cAMP levels when activated. Increased level of cAMP is associated with the inhibition of epidermal cell proliferation. In the present study, we observed the effect of salmeterol, a long-acting β₂-AR agonist, on the proliferation and apoptosis of keratinocytes as well as imiquimod-induced psoriasis-like skin lesions in mice. As phosphodiesterase 4 (PDE4) inhibitors increases intracellular cAMP concentration by inhibiting its inactivation, we further explored the synergetic effect of a PDE4 inhibitor and salmeterol on psoriasis-like skin lesions in mice. Our results indicated that salmeterol effectively inhibited the proliferation of HaCaT cells induced by TNF-α and serum, and this effect was accompanied by significantly increased apoptosis and CREB phosphorylation, which were reversed by the PKA inhibitor, H89. Salmeterol ameliorated imiquimod-induced psoriasis-like skin lesions in mice, but salmeterol combined with a PDE4 inhibitor had no synergetic effect in improving skin lesions in mice. Of note, the synergistic effects of anti-proliferation and induction of apoptosis in HaCaT cells appeared by inhibiting ERK signaling. In summary, salmeterol, a long-acting β₂-AR agonist, alleviates the severity of psoriasis via inhibiting the proliferation and promoting apoptosis of keratinocytes, partially by activating the cAMP/PKA signaling pathway.

Emerging Roles of Post-Translational Modifications in Skin Diseases: Current Knowledge, Challenges and Future Perspectives

Post-translational modifications (PTMs) of proteins represent as a key step in regulating their biological functions and dynamic interaction with other players. This process is fine-tuned by a myriad of enzymes named “writers, readers and erasers” whose actions are precisely controlled. Either the mutation, aberration in the expression of the aforementioned enzymes or their substrates have shown to participate in the pathogenesis of various skin diseases such as melanoma, vitiligo, psoriasis, eczema, atopic dermatitis and inherited dermatological diseases. It is becoming increasingly clear that key transcriptional factors, inflammation-related molecules are prone to PTMs. Despite their importance in regulating key processes including inflammation, keratinocyte apoptosis, proliferation and differentiation, PTMs have received less attention due to the challenges involved. Here in this review we summarize the role of the most common types and the newly discovered PTMs, including acetylation, glycosylation, citrullination, PARylation and sumoylation in dermatoses and surveys the recent progress in PTM-based therapeutic approaches in skin diseases.

Acitretin-Conjugated Dextran Nanoparticles Ameliorate Psoriasis-like Skin Disease at Low Dosages

Psoriasis is a common chronic inflammatory skin disease mainly characterized by keratinocyte hyperproliferation and massive infiltration of inflammatory immune cells. Acitretin (ACT), an FDA-approved first-line systemic drug for psoriasis treatment, could suppress the proliferation of keratinocytes and downregulate the expression of inflammatory cytokines by modulating signal transducer and activator of transcription (STAT) signaling pathways. However, dose-dependent side effects of ACT limit its long-term administration in the clinic. Therefore, improving the therapeutic efficacy of ACT to reduce clinical dosage will benefit the patients. Here, we develop ACT-conjugated dextran nanoparticles (ACT-Dex NPs) and evaluated the potential for psoriasis treatment. Our results indicate that ACT-Dex NPs ameliorate psoriasis-like skin disease significantly at a low dosage which does not cause side effects, while neat ACT drugs at an equivalent dosage provide much less benefit. Moreover, we demonstrate that ACT-Dex NPs suppress keratinocyte proliferation more efficiently than neat ACT by enhancing the inhibitory effect on STAT3 phosphorylation. Thus, the proposed ACT-Dex NPs provide an effective and safe option for psoriasis treatment.

Sirtuin Oxidative Post-translational Modifications

Increased sirtuin deacylase activity is correlated with increased lifespan and healthspan in eukaryotes. Conversely, decreased sirtuin deacylase activity is correlated with increased susceptibility to aging-related diseases. However, the mechanisms leading to decreased sirtuin activity during aging are poorly understood. Recent work has shown that oxidative post-translational modification by reactive oxygen (ROS) or nitrogen (RNS) species results in inhibition of sirtuin deacylase activity through cysteine nitrosation, glutathionylation, sulfenylation, and sulfhydration as well as tyrosine nitration. The prevalence of ROS/RNS (e.g., nitric oxide, S-nitrosoglutathione, hydrogen peroxide, oxidized glutathione, and peroxynitrite) is increased during inflammation and as a result of electron transport chain dysfunction. With age, cellular production of ROS/RNS increases; thus, cellular oxidants may serve as a causal link between loss of sirtuin activity and aging-related disease development. Therefore, the prevention of inhibitory oxidative modification may represent a novel means to increase sirtuin activity during aging. In this review, we explore the role of cellular oxidants in inhibiting individual sirtuin human isoform deacylase activity and clarify the relevance of ROS/RNS as regulatory molecules of sirtuin deacylase activity in the context of health and disease.

PI3Kδ Sustains Keratinocyte Hyperproliferation and Epithelial Inflammation: Implications for a Topically Druggable Target in Psoriasis

The phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathway is aberrantly activated in psoriatic lesions and contributes to disease pathogenesis. Among PI3Ks enzymes, PI3Kα, β, and δ isoforms are known to bind the p85 regulatory subunit and mediate activation of AKT and other downstream effectors. In this study, we deepened our understanding of the expression and function of PI3Kδ in skin lesions of patients affected by psoriasis. For the first time, we found that PI3Kδ is overexpressed in psoriatic plaques, and its expression is not only confined to infiltrating immune cells but also accumulates in proliferating keratinocytes of the epidermal basal layer. We investigated the function of PI3Kδ in psoriatic skin by evaluating the impact of seletalisib, a newly developed selective PI3Kδ inhibitor, in both in vitro and in vivo experimental models of psoriasis. Of note, we found that PI3Kδ sustains keratinocyte hyperproliferation and impaired terminal differentiation induced by IL-22, as well as induces epithelial inflammation and resistance to apoptosis mediated by TNF-α in human keratinocytes. Mechanistically, PI3Kδ promotes PDK1 phosphorylation and signals through AKT-dependent or -independent pathways. It is worth mentioning that PI3Kδ inhibition by seletalisib attenuates the severity of psoriasiform phenotype induced in the Imiquimod-induced mouse model of psoriasis by restoring the physiological proliferation and differentiation programs in epidermal keratinocytes and contrasting the cutaneous inflammatory responses. Therefore, we suggest PI3Kδ as a potential topically druggable target in psoriasis and skin diseases characterized by epidermal hyperproliferation and skin inflammation.

Interleukin-22: a potential therapeutic target in atherosclerosis

BACKGROUND

Atherosclerosis is recognized as a chronic immuno-inflammatory disease that is characterized by the accumulation of immune cells and lipids in the vascular wall. In this review, we focus on the latest advance regarding the regulation and signaling pathways of IL-22 and highlight its impacts on atherosclerosis.

MAIN BODY

IL-22, an important member of the IL-10 family of cytokines, is released by cells of the adaptive and innate immune system and plays a key role in the development of inflammatory diseases. The binding of IL-22 to its receptor complex can trigger a diverse array of downstream signaling pathways, in particular the JAK/STAT, to induce the expression of chemokines and proinflammatory cytokines. Recently, numerous studies suggest that IL-22 is involved in the pathogenesis of atherosclerosis by regulation of VSMC proliferation and migration, angiogenesis, inflammatory response, hypertension, and cholesterol metabolism.

CONCLUSION

IL-22 promotes the development of atherosclerosis by multiple mechanisms, which may be a promising therapeutic target in the pathogenesis of atherosclerosis.

Delivery and Anti-Psoriatic Effect of Silibinin-Loaded Polymeric Micelles: An Experimental Study in the Psoriatic Skin Model

OBJECTIVE

Psoriasis is an inflamed skin disorder associated with the activation of phosphorylation signals in keratinocytes, which leads to proliferation. Phosphorylation signal inhibitors, such as silibinin can inhibit cell proliferation. Unlike current psoriasis treatment approaches that are associated with dangerous side effects; natural components can introduce new trends in psoriasis treatment. The major problem in the topical treatment of psoriasis is drug localization through the psoriasis lesions.

METHODS

In this study, silibinin-loaded polymeric micelles prepared and characterized for drug loading and release and ex vivo permeation through psoriatic and normal mice skin. The optimized batch was used for the treatment of psoriasis lesions in the mice model.

RESULTS

The optimized batch demonstrated mean particle size 18.3 ± 2.1 nm, entrapment efficiency 75.8 ± 5.8%, and prolonged silibinin release. % Silibinin permeated through psoriatic skin after 48 treated by polymeric micelle and aqueous control was 80.35, and 92.6, respectively. Polymeric micelles increased silibinin localization in the psoriatic skin in comparison with control. In psoriatic skin after 7- 10 days treatment by silibinin- loaded polymeric micelle, there was no evidence of psoriasis and the histological evaluation showed no sign of psoriasis. Silibinin-loaded polymeric micelles reduced Psoriasis area index by more than 78% after 14 days.

CONCLUSION

It seems that polymeric micelles increased the effectiveness of silibinin by drug localization into the psoriatic plaque. Topical STAT- 3inhibitors can be introduced as a new strategy in psoriasis treatment.

The role of understudied post-translational modifications for the behavior and function of Signal Transducer and Activator of Transcription 3

The Signal Transducer and Activator of Transcription (STAT) family of transcription factors is involved in inflammation, immunity, development, cancer, and response to injury, among other biological phenomena. Canonical STAT signaling is often represented as a 3-step pathway involving the sequential activation of a membrane receptor, an intermediate kinase, and a STAT transcription factor. The rate-limiting phosphorylation at a highly conserved C-terminal tyrosine residue determines the nuclear translocation and transcriptional activity of STATs. This apparent simplicity is actually misleading and can hardly explain the pleiotropic nature of STATs, the existence of various noncanonical STAT pathways, or the key role of the N-terminal domain in STAT functions. More than 80 post-translational modifications (PTMs) have been identified for STAT3, but their functions remain barely understood. Here, we provide a brief but comprehensive overview of these underexplored PTMs and their role on STAT3 canonical and noncanonical functions. A less tyrosine-centric point of view may be required to advance our understanding of STAT signaling.

Enhanced NAMPT-Mediated NAD Salvage Pathway Contributes to Psoriasis Pathogenesis by Amplifying Epithelial Auto-Inflammatory Circuits

Dysregulated cross-talk between immune cells and epithelial compartments is responsible for the onset and amplification of pathogenic auto-inflammatory circuits occurring in psoriasis. NAMPT-mediated NAD salvage pathway has been recently described as an immunometabolic route having inflammatory function in several disorders, including arthritis and inflammatory bowel diseases. To date, the role of NAD salvage pathway has not been explored in the skin of patients affected by psoriasis. Here, we show that NAD content is enhanced in lesional skin of psoriatic patients and is associated to high NAMPT transcriptional levels. The latter are drastically reduced in psoriatic skin following treatment with the anti-IL-17A biologics secukinumab. We provide evidence that NAMPT-mediated NAD⁺ metabolism fuels the immune responses executed by resident skin cells in psoriatic skin. In particular, intracellular NAMPT, strongly induced by Th1/Th17-cytokines, acts on keratinocytes by inducing hyper-proliferation and impairing their terminal differentiation. Furthermore, NAMPT-mediated NAD⁺ boosting synergizes with psoriasis-related cytokines in the upregulation of inflammatory chemokines important for neutrophil and Th1/Th17 cell recruitment. In addition, extracellular NAMPT, abundantly released by keratinocytes and dermal fibroblasts, acts in a paracrine manner on endothelial cells by inducing their proliferation and migration, as well as the expression of ICAM-1 membrane molecule and chemokines important for leukocyte recruitment into inflamed skin. In conclusion, our results showed that NAMPT-mediated NAD salvage pathway contributes to psoriasis pathogenic processes by amplifying epithelial auto-inflammatory responses in psoriasis.

Resveratrol Alleviates 27-Hydroxycholesterol-Induced Senescence in Nerve Cells and Affects Zebrafish Locomotor Behavior via Activation of SIRT1-Mediated STAT3 Signaling

The oxysterol 27-hydroxycholesterol (27HC) is the first identified endogenous selective estrogen receptor modulator (SERM), which like endogenous estrogen 17β-estradiol (E₂) induces the proliferation of estrogen receptor- (ER-) positive breast cancer cells in vitro. However, 27HC differs from E₂ in that it shows adverse effects in the nervous system. Our previous study confirmed that 27HC could induce neural senescence by activating phosphorylated signal transducer and activator of transcription, which E₂ could not. The purpose of the present study is to investigate whether STAT3 acetylation was involved in 27HC-induced neural senescence. Microglia (BV2 cells) and rat pheochromocytoma cells (PC12 cells) were used in vitro to explore the effect of resveratrol (REV) on 27HC-induced neural senescence. Senescence-associated β-galactosidase (SA-β-Gal) staining was performed using an SA-β-Gal Staining Kit in cells and zebrafish larvae. Zebrafish were used in vivo to assess the effect of 27HC on locomotor behavior and aging. We found that 27HC could induce senescence in neural cells, and REV, which has been employed as a Sirtuin-1 (SIRT1) agonist, could attenuate 27HC-induced senescence by inhibiting STAT3 signaling via SIRT1. Moreover, in the zebrafish model, REV attenuated 27HC-induced locomotor behavior disorder and aging in the spinal cord of zebrafish larvae, which was also associated with the activation of SIRT1-mediated STAT3 signaling. Our findings unveiled a novel mechanism by which REV alleviates 27HC-induced senescence in neural cells and affects zebrafish locomotor behavior by activating SIRT1-mediated STAT3 signaling.

Glycyrrhizin improves the pathogenesis of psoriasis partially through IL-17A and the SIRT1-STAT3 axis

Background

The anti-inflammatory effect of glycyrrhizin has been widely recognized, while the specific mechanism of glycyrrhizin in psoriasis remains poorly understood.

Results

In the imiquimod-induced mouse model of psoriasis (IMD), we found that glycyrrhizin can substantially improve the adverse symptoms in mice. The hematoxylin-eosin staining results showed that glycyrrhizin can also improve the pathological state of skin cells in IMD mice. Using enzyme-linked immunosorbent assay (ELISA), we found that glycyrrhizin substantially inhibited the expression of IL-17A and IFN-γ in the serum of IMD mice. In order to simulate the effect of IL-17A on keratinocytes in psoriasis, we treated HaCaT cells with 100 ng/mL IL-17A (IL-17A-HaCaT cells) for 48 h. Then, using cell-counting kit-8 (CCK-8) and ELISA assays, we found that glycyrrhizin inhibited the proliferation of IL-17A-HaCaT cells and reversed the promotion of IL-6, CCL20, and TNF-α induced by IL-17A. Further, western blotting (WB) results indicated that glycyrrhizin promoted the expression of SIRT1 and inhibited the expression of STAT3 and phosphorylated STAT3 (p-STAT3). By treating IL-17A-HaCaT cells with EX-527 (a potent and selective inhibitor of SIRT1), combined with CCK-8 and WB experiments, we initially found that EX-527 inhibited the proliferation of IL-17A-HaCaT cells and promoted the expression of STAT3, p-STAT3, and acetylated STAT3 (a-STAT3). However, when glycyrrhizin was added at the same time, the proliferation of IL-17A-HaCaT cells increased, and the expression of STAT3, p-STAT3, and a-STAT3 reduced. We then knocked down the expression of SIRT1 via small interfering RNA in IL-17A-HaCaT cells, and the results were consistent with those of EX-527.

Conclusions

Together, these results indicated that glycyrrhizin improved psoriasis by inhibiting the expression of IL-17A and IFN-γ in vivo and suppressed the proliferation of IL-17A-HaCaT cells and the expression of STAT3, p-STAT3, and a-STAT3 by upregulating SIRT1 in vitro.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00421-z.

Janus Kinase Inhibitors in Dermatology: Part 2: Applications in Psoriasis, Atopic Dermatitis, and Other Dermatoses

Dermatologists' interest in the Janus-associated kinase (JAK)/signal transducers and activators of transcription (STAT) pathway has been growing as evidence builds to support its key role in the pathogenesis of inflammatory skin diseases. Because certain proinflammatory cytokines use the JAK/STAT pathway for signal transduction, it has become a promising therapeutic target in diseases where selective modulation of the immune system can be useful. We aim to review current knowledge of the JAK/STAT signaling pathway and its role in immune-mediated skin diseases. In the second part of the review we cover the efficacy and safety of oral and topical JAK inhibitors in the treatment of psoriasis, atopic dermatitis, and other skin diseases.

Advances in the Application of Natural Products and the Novel Drug Delivery Systems for Psoriasis

Psoriasis, an incurable autoimmune skin disease, is one of the most common immune-mediated disorders. Presently, numerous clinical research studies are underway, and treatment options are available. However, these treatments focus on improving symptoms of the disease and fail to achieve a radical cure; they also have certain toxic side effects. In recent years, natural products have increasingly gained attention because of their high efficiency and low toxicity. Despite their obvious therapeutic effects, natural products’ biological activity was limited by their instability, poor solubility, and low bioavailability. Novel drug delivery systems, including liposomes, lipospheres, nanostructured lipid carriers, niosomes, nanoemulsions, nanospheres, microneedles, ethosomes, nanocrystals, and foams could potentially overcome the limitations of poor water solubility and permeability in traditional drug delivery systems. Thus, to achieve a therapeutic effect, the drug can reach the epidermis and dermis in psoriatic lesions to interact with the immune cells and cytokines.

Janus Kinase Inhibitors in Dermatology: Part 2: Applications in Psoriasis, Atopic Dermatitis, and Other Dermatoses

Dermatologists' interest in the Janus-associated kinase (JAK)/signal transducers and activators of transcription (STAT) pathway has been growing as evidence builds to support its key role in the pathogenesis of inflammatory skin diseases. Because certain proinflammatory cytokines use the JAK/STAT pathway for signal transduction, it has become a promising therapeutic target in diseases where selective modulation of the immune system can be useful. We aim to review current knowledge of the JAK/STAT signaling pathway and its role in immune-mediated skin diseases. In the second part of the review we cover the efficacy and safety of oral and topical JAK inhibitors in the treatment of psoriasis, atopic dermatitis, and other skin diseases.

Weighted gene coexpression network and experimental analyses identify lncRNA SPRR2C as a regulator of the IL-22-stimulated HaCaT cell phenotype through the miR-330/STAT1/S100A7 axis

Psoriasis is a chronic inflammatory disease of the skin with highly complex pathogenesis. In this study, we identified lncRNA SPRR2C (small proline-rich protein 2C) as a hub gene with a critical effect on the pathogenesis of psoriasis and response to treatment using both weighted gene coexpression network analysis (WGCNA) and differential expression analysis. SPRR2C expression was significantly upregulated in both psoriatic lesion samples and HaCaT cell lines in response to IL-22 treatment. After SPRR2C knockdown, IL-22-induced suppression of HaCaT proliferation, changes in the KRT5/14/1/10 protein levels, and suppression of the IL-1β, IL-6, and TNF-α mRNA levels were dramatically reversed. In the coexpression network with SPRR2C based on GSE114286, miR-330 was significantly negatively correlated with SPRR2C, while STAT1 and S100A7 were positively correlated with SPRR2C. By binding to miR-330, SPRR2C competed with STAT1 and S100A7 to counteract miR-330-mediated suppression of STAT1 and S100A7. MiR-330 overexpression also reversed the IL-22-induced changes in HaCaT cell lines; in response to IL-22 treatment, miR-330 inhibition significantly attenuated the effects of SPRR2C knockdown. STAT1 and S100A7 expression was significantly upregulated in psoriatic lesion samples. The expression of miR-330 had a negative correlation with the expression of SPRR2C, while the expression of SPRR2C had a positive correlation with the expression of STAT1 and S100A7. Thus, SPRR2C modulates the IL-22-stimulated HaCaT cell phenotype through the miR-330/STAT1/S100A7 axis. WGCNA might uncover additional biological pathways that are crucial in the pathogenesis and response to the treatment of psoriasis.

EZH2-dependent epigenetic modulation of histone H3 lysine-27 contributes to psoriasis by promoting keratinocyte proliferation

Psoriasis is characterized by keratinocyte hyperproliferation. While significant progress has been made in understanding the molecular mechanism regulating the proliferation of keratinocytes, little is known about the epigenetic factors that control this process. EZH2 and EZH2 mediated trimethylation of histone H3 lysine 27 (H3K27me3) was previously shown ectopically expressed in carcinoma and mediated proliferation, thereby we sought to clarify the role of EZH2–H3K27me3 in the proliferation of psoriatic keratinocyte. Interestingly, we found that EZH2 and H3K27me3 were both overexpressed in the epidermis of psoriatic lesional skin compared to normal skin. In vitro, the expression of EZH2 and H3K27me3 was stimulated in human keratinocytes treated with mixture of psoriasis-related cytokines pool (TNF-α, IFN-γ, IL-17A, and IL-22). Knockdown of EZH2 significantly reduced keratinocyte proliferative activity. Results from mRNA microarray analysis suggested that Kallikrein-8 (KLK8) might be the target gene of EZH2 in psoriatic keratinocytes. Overexpression or knockdown KLK8 could partially reverse the abnormal proliferation of keratinocytes caused by knockdown or overexpression of EZH2. In vivo, the inhibitor of EZH2, GSK126 could ameliorate the imiquimod-induced psoriasiform lesion. These results suggest that EZH2 might be a therapeutic target for the treatment of psoriasis.

Histone Deacetylase 1 and Sirtuin 1 Expression in Psoriatic Skin: A Comparison between Guttate and Plaque Psoriasis

Abnormal histone modification by histone deacetylases (HDACs), including HDAC1 and sirtuin 1 (SIRT1), has been reported to play an important role in the pathogenesis of psoriasis by altering cell proliferation, differentiation, and inflammation. However, findings on the expression level of HDACs in psoriatic skin lack consistency. We assessed the expression of HDAC1, SIRT1, p63, and proliferating cell nuclear antigen (PCNA) in skin tissues from 23 patients with psoriasis (15 with plaque psoriasis and eight with guttate psoriasis) and five healthy individuals using immunohistochemistry, and analyzed their associations with clinical phenotypes of the disease. The expression of HDAC1 and keratinocyte proliferative markers, such as p63 and PCNA significantly increased, whereas that of SIRT1 decreased in the basal layer (p < 0.05) of the patients with psoriasis compared to those in healthy controls. Among the patients with psoriasis, expression of HDAC1, p63, and PCNA was significantly higher in plaque psoriasis than in guttate psoriasis. There was no significant differences in the level of SIRT1 between the two clinical phenotypes. The findings of this study suggest that histone modifications are involved in the pathogenesis of psoriasis and may contribute to the formation of clinical phenotypes.

Role of SIRT1 in HIV-associated kidney disease

Human immunodeficiency virus (HIV) infection of kidney cells can lead to HIV-associated nephropathy (HIVAN) and aggravate the progression of other chronic kidney diseases. Thus, a better understanding of the mechanisms of HIV-induced kidney cell injury is needed for effective therapy against HIV-induced kidney disease progression. We have previously shown that the acetylation and activation of key inflammatory regulators, NF-κB p65 and STAT3, were increased in HIVAN kidneys. Here, we demonstrate the key role of sirtuin 1 (SIRT1) deacetylase in the regulation of NF-κB and STAT3 activity in HIVAN. We found that SIRT1 expression was reduced in the glomeruli of human and mouse HIVAN kidneys and that HIV-1 gene expression was associated with reduced SIRT1 expression and increased acetylation of NF-κB p65 and STAT3 in cultured podocytes. Interestingly, SIRT1 overexpression, in turn, reduced the expression of negative regulatory factor in podocytes stably expressing HIV-1 proviral genes, which was associated with inactivation of NF-κB p65 and a reduction in HIV-1 long terminal repeat promoter activity. In vivo, the administration of the small-molecule SIRT1 agonist BF175 or inducible overexpression of SIRT1 specifically in podocytes markedly attenuated albuminuria, kidney lesions, and expression of inflammatory markers in Tg26 mice. Finally, we showed that the reduction in SIRT1 expression by HIV-1 is in part mediated through miR-34a expression. Together, our data provide a new mechanism of SIRT1 regulation and its downstream effects in HIV-1-infected kidney cells and indicate that SIRT1/miR-34a are potential drug targets to treat HIV-related kidney disease.

310 nm UV-LEDs attenuate imiquimod-induced psoriasis-like skin lesions in C57BL/6 mice and inhibit IL-22-induced STAT3 expression in HaCaT cells

Ultraviolet light-emitting diodes (UV-LEDs) are a novel light source for phototherapy. This study aimed to evaluate the therapeutic effects of UV-LEDs on psoriasis. Importantly, 310 nm UV-LEDs have not been studied in psoriasis in vitro and in vivo. Effects due to 310 nm UV-LED and 311 nm narrowband ultraviolet B (NBUVB) irradiation were compared for suppressing IL-22-induced activation of STAT3 expression using cell viability assay, western blotting, and immunocytochemistry. C57BL/6 mice were topically treated with imiquimod (IMQ) for 6 consecutive days and degenerative changes were observed. Test groups were irradiated with a 310 nm UV-LED and 311 nm NBUVB. Phenotypic observations, histopathological examinations, and ELISA were conducted with skin and blood samples. STAT3-dependent IL-22 signalling and effects in keratinocytes are negatively regulated by the 310 nm UV-LED, which significantly ameliorated IMQ-induced psoriasis-like dermatitis development and reduced Th17 cytokine levels (IL-17A, IL-22) in serum and dorsal skin. Histopathological findings showed decreases in epidermal thickness and inflammatory T-cell infiltration in the UV-LED-irradiated groups. Quantitative PCR confirmed a UV radiation energy-dependent decrease in IL-17A and IL-22 mRNA levels. The results demonstrated that UV-LEDs had anti-inflammatory and immunoregulatory effects. So, UV-LED phototherapy inhibits psoriasis development by suppressing STAT3 protein and inflammatory cytokines and could be useful in treating psoriasis.

Interleukin (IL)-17/IL-36 axis participates to the crosstalk between endothelial cells and keratinocytes during inflammatory skin responses

In inflammatory skin conditions, such as psoriasis, vascular enlargement is associated with endothelial cell proliferation, release of cytokines and adhesion molecule expression. Interleukin (IL)-17A is a pro-inflammatory cytokine mainly secreted by T helper-17 cells that is critically involved in psoriasis pathogenesis. IL-36α, IL-36β and IL-36γ are also inflammatory cytokines up-regulated in psoriasis and induced by various stimuli, including IL-17A. In this study, we found that human keratinocytes are the main source of IL-36, in particular of IL-36γ. This cytokine was strongly induced by IL-17A and, together with IL-17A, efficiently activated human dermal microvascular endothelial cells (HDMECs), which expressed both IL-17 and IL-36 receptors. Both IL-36γ and IL-17A induced cell proliferation through specific molecular cascades involving ERK1/2 only or ERK1/2, STAT3 and NF-κB, respectively. We highlighted the intense IL-17A- and IL-36γ -dependent interplay between keratinocytes and HDMECs, likely active in the psoriatic lesions and leading to the establishment of a cytokine network responsible for the development and maintenance of the inflamed state. IL-17A or IL-36γ showed in HDMECs a synergic activity with TNF-α by potently inducing inflammatory cytokine/chemokine release and ICAM-1 expression. We also investigated the involvement of IL-36γ and VEGF-A, substantially reduced in lesional skin of psoriatic patients pharmacologically treated with the anti-IL-17A antibody Secukinumab. Importantly, keratinocyte-derived IL-36γ represented an additional pro-angiogenic mediator of IL-17A. We observed that keratinocyte-derived VEGF-A influenced proliferation but did not act on expression of adhesion molecules in HDMECs. On the other hand, inhibition of IL-36γ released by IL-17A-treated keratinocytes impaired either proliferation or ICAM-1 expression both in HDMECs and in an in vivo murine model of psoriasis. Taken together, our data demonstrated that IL-17A and IL-36γ are highly involved in endothelial cells/keratinocytes crosstalk in inflammatory skin conditions.

Baicalin Inhibits Cell Proliferation and Inflammatory Cytokines Induced by Tumor Necrosis Factor α (TNF-α) in Human Immortalized Keratinocytes (HaCaT) Human Keratinocytes by Inhibiting the STAT3/Nuclear Factor kappa B (NF-κB) Signaling Pathway

Background

Baicalin is a flavone isolated from the root of Scutellaria baicalensis and is used in traditional Chinese medicine. Psoriasis is a persistent and recurrent chronic inflammatory skin disease that is characterized by inflammation and increased proliferation of keratinocytes. This study aimed to investigate the effects of baicalin on HaCaT immortalized human keratinocytes in vitro and the molecular mechanisms involved.

Material/Methods

HaCaT keratinocytes were cultured in increasing concentrations of baicalin at 6.25 μM, 12.5 μM, and 25 μM. The in vitro model of psoriasis was established using HaCaT cells treated with tumor necrosis factor-α (TNF-α). The MTT assay was used to asses cell viability and apoptosis. Western blot was used to measure the expression of Bcl-2, Bax, pro-caspase-3, and cleaved caspase-3, and enzyme-linked immunosorbent assay (ELISA) was performed to detect inflammatory cytokines. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the levels of STAT3 and p65 mRNA.

Results

Baicalin reduced cell viability and induced apoptosis of HaCaT human keratinocytes in a dose-dependent manner. Increased cell viability and the expression of inflammatory cytokines by HaCaT cells induced by TNF-α were significantly inhibited by baicalin. Baicalin significantly inhibited the activation of the STAT3/NF-κB pathway in HaCaT cells stimulated by TNF-α.

Conclusions

Baicalin inhibited the proliferation and expression of inflammatory cytokines in HaCaT immortalized human keratinocytes in vitro through the inhibition of the STAT3/NF-κB signaling pathway.

ERK Dephosphorylation through MKP1 Deacetylation by SIRT1 Attenuates RAS-Driven Tumorigenesis

The role of Situin 1 (SIRT1) in tumorigenesis is still controversial due to its wide range of substrates, including both oncoproteins and tumor suppressors. A recent study has demonstrated that SIRT1 interferes in the Kirsten rat sarcoma viral oncogene homolog (KRAS)-driven activation of the Raf-mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK pathway, thereby inhibiting tumorigenesis. However, the molecular mechanism of SIRT1 as a tumor suppressor in RAS-driven tumorigenesis has been less clearly determined. This study presents evidence that the ectopic expression of SIRT1 attenuates RAS- or MEK-driven ERK activation and reduces cellular proliferation and transformation in vitro. The attenuation of ERK activation by SIRT1 results from prompt dephosphorylation of ERK, while MEK activity remains unchanged. We identified that MKP1, a dual specific phosphatase for MAPK, was deacetylated by SIRT1. Deacetylation of MKP1 by direct interaction with SIRT1 increased the binding affinity to ERK which in turn facilitated inactivation of ERK. Taken together, these results suggest that SIRT1 would act as a tumor suppressor by modulating RAS-driven ERK activity through MKP1 deacetylation.

Salidroside inhibits MAPK, NF-κB, and STAT3 pathways in psoriasis-associated oxidative stress via SIRT1 activation

Objectives: To unveil the role of SIRT1 in limiting oxidative stress in psoriasis and to further discuss the therapeutic prospects of salidroside in psoriasis.

Methods: Literature from 2002 to 2019 was searched with “psoriasis”, “oxidative stress”, “SIRT1”, “salidroside” as the key words. Then, Oxidative stress in psoriasis and the role of SIRT1 were summarized and the potential role of salidroside in the disease was speculated.

Results: Oxidative stress might contribute to the pathogenesis of psoriasis. High levels of ROS produced during oxidative stress lead to the release of inflammatory mediators, that, in turn, induce angiogenesis and excessive proliferation of keratinocytes. SIRT1 is a member of the sirtuin family, of which the activation lead to the inhibition of such oxidative stress signaling pathways MAPK, NF-κB, and STAT3, down-regulation of inflammatory factors, suppression of inflammation and keratinocyte hyperproliferation, and inhibition of angiogenesis. Salidroside, the main ingredient of Rhodiola, is known to exert antioxidant roles, which has been attributed to SIRT1 activation.

Conclusion: Salidroside might inhibit oxidative stress singling pathways via SIRT1 activation, and could be as an ideal candidate for management of psoriasis.

Recapitulating T cell infiltration in 3D psoriatic skin models for patient-specific drug testing

Drug screening studies for inflammatory skin diseases are currently performed using model systems that only partially recapitulate human diseased skin. Here, we developed a new strategy to incorporate T cells into human 3D skin constructs (HSCs), which enabled us to closely monitor and quantitate T cell responses. We found that the epidermis promotes the activation and infiltration of T cells into the skin, and provides a directional cue for their selective migration towards the epidermis. We established a psoriatic HSC (pHSC) by incorporating polarized Th1/Th17 cells or CCR6+CLA+ T cells derived from psoriasis patients into the constructs. These pHSCs showed a psoriatic epidermal phenotype and characteristic cytokine profiles, and responded to various classes of psoriasis drugs, highlighting the potential utility of our model as a drug screening platform. Taken together, we developed an advanced immunocompetent 3D skin model to investigate epidermal-T cell interactions and to understand the pathophysiology of inflammatory skin diseases in a human-relevant and patient-specific context.

The Oxidative Stress-Induced miR-200c Is Upregulated in Psoriasis and Correlates with Disease Severity and Determinants of Cardiovascular Risk

Psoriasis is a chronic inflammatory skin disease associated with reactive oxygen species (ROS) increase and a higher risk of cardiovascular (CV) events. We previously showed that the miR-200 family (miR-200s) is induced by ROS, miR-200c being the most upregulated member responsible for apoptosis, senescence, ROS increase, and nitric oxide decrease, finally causing endothelial dysfunction. Moreover, circulating miR-200c increases in familial hypercholesterolemic children and in plaques and plasma of atherosclerotic patients, two pathologies associated with increased ROS. Given miR-200s' role in endothelial dysfunction, ROS, and inflammation, we hypothesized that miR-200s were modulated in lesional skin (LS) and plasma of psoriatic patients (Pso) and that their levels correlated with some CV risk determinants at a subclinical level. All Pso had severe psoriasis, i.e., Psoriasis Area and Severity Index (PASI) > 10, and one of the following: at least two systemic psoriasis treatments, age at onset < 40 years, and disease duration > 10 years. RNA was extracted from plasma (Pso, N = 29; Ctrl, N = 29) and from nonlesional skin (NLS) and LS of 6 Pso and 6 healthy subject skin (HS) biopsies. miR-200 levels were assayed by quantitative RT-PCR. We found that all miR-200s were increased in LS vs. NLS and miR-200c was the most expressed and upregulated in LS vs. HS. In addition, circulating miR-200c and miR-200a were upregulated in Pso vs. Ctrl. Further, miR-200c positively correlated with PASI, disease duration, left ventricular (LV) mass, LV relative wall thickness (RWT), and E/e', a marker of diastolic dysfunction. Multiple regression analysis indicates a direct association between miR-200c and both RWT and LV mass. Circulating miR-200a correlated positively only with LV mass and arterial pressure augmentation index, a measure of stiffness, although the correlations were nearly significant (P = 0.06). In conclusion, miR-200c is upregulated in LS and plasma of Pso, suggesting its role in ROS increase and inflammation associated with CV risk in psoriasis.

IL-18/IL-18BP and IL-22/IL-22BP: Two interrelated couples with therapeutic potential

Interleukin (IL)-18 and IL-22 are key components of cytokine networks that play a decisive role in (pathological) inflammation, host defense, and tissue regeneration. Tight regulation of cytokine-driven signaling, inflammation, and immunoactivation is supposed to enable nullification of a given deleterious trigger without mediating overwhelming collateral tissue damage or even activating a cancerous face of regeneration. In fact, feedback regulation by specific cytokine opponents is regarded as a major means by which the immune system is kept in balance. Herein, we shine a light on the interplay between IL-18 and IL-22 and their opponents IL-18 binding protein (IL-18BP) and IL-22BP in order to provide integrated information on their biology, pathophysiological significance, and prospect as targets and/or instruments of therapeutic intervention.

Paradoxical psoriasis induced by TNF-α blockade shows immunological features typical of the early phase of psoriasis development

Immunomodulation with anti‐TNF‐α is highly effective in the treatment of various immune‐mediated inflammatory diseases, including hidradenitis suppurativa (HS). However, this may be responsible for unexpected paradoxical psoriasiform reactions. The pathogenic mechanisms underlying the induction of these events are not clear, even though the involvement of innate immune responses driven by plasmacytoid dendritic cells (pDC) has been described. In addition, the genetic predisposition to psoriasis of patients could be determinant. In this study, we investigated the immunological and genetic profiles of three HS patients without psoriasis who developed paradoxical psoriasiform reactions following anti‐TNF‐α therapy with adalimumab. We found that paradoxical psoriasiform skin reactions show immunological features common to the early phases of psoriasis development, characterized by cellular players of innate immunity, such as pDC, neutrophils, mast cells, macrophages, and monocytes. In addition, IFN‐β and IFN‐α2a, two type I IFNs typical of early psoriasis, were highly expressed in paradoxical skin reactions. Concomitantly, other innate immunity molecules, such as the catheledicin LL37 and lymphotoxin (LT)‐α and LT‐β were overproduced. Interestingly, these innate immunity molecules were abundantly expressed by keratinocytes, in addition to the inflammatory infiltrate. In contrast to classical psoriasis, psoriasiform lesions of HS patients showed a reduced number of IFN‐γ and TNF‐α‐releasing T lymphocytes. On the contrary, IL‐22 immunoreactivity was significantly augmented together with the IL‐36γ staining in leukocytes infiltrating the dermis. Finally, we found that all HS patients with paradoxical reactions carried allelic variants in genes predisposing to psoriasis. Among them, SNPs in ERAP1, NFKBIZ, and TNFAIP genes and in the HLA‐C genomic region were found.

Resveratrol decreases CD45+ CD206- subtype macrophages in LPS-induced murine acute lung injury by SOCS3 signalling pathway

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) are life-threatening condition in critically ill patients. Resveratrol (Res), a natural polyphenol, has therapeutic effect in animal model with ALI; however, whether Res attenuates ALI through modulation of macrophage phenotypes in the animal model remains unknown. We in this study treated LPS-induced murine ALI with 30 mg/kg Res and observed significantly reduced severity of ALI in the Res-treated mice 48 hours after Res treatment. Neutrophil infiltrates were significantly reduced, accompanied with lower infiltration of CD45⁺ Siglec F^- phenotype macrophages, but higher population of CD45⁺ Siglec F⁺ and CD45⁺ CD206⁺ alternatively activated macrophages (M2 cells) in the Res-treated mice with ALI. In addition, the expression of IL-1beta and CXCL15 cytokines was suppressed in the treated mice. However, Res treatment in mice with myeloid cell-restricted SOCS3 deficiency did not significantly attenuate ALI severity and failed to increase population of both CD45⁺ Siglec F⁺ and CD45⁺ CD206⁺ M2 subtype macrophages in the murine ALI. Further studies in wild-type macrophages revealed that Res treatment effectively reduced the expression of IL-6 and CXCL15, and increased the expression of arginase-1, SIRT1 and SOCS3. However, macrophages' lack of SOCS3 expression were resistant to the Res-induced suppression of IL-6 and CXCL15 in vitro. Thus, we conclude that Res suppressed CD45⁺ Siglec F^- and CD45⁺ CD206^- M1 subtype macrophages through SOCS3 signalling in the LPS-induced murine ALI.

Epigenetic inhibition of the tumor suppressor ARHI by light at night-induced circadian melatonin disruption mediates STAT3-driven paclitaxel resistance in breast cancer

Disruption of circadian time structure and suppression of circadian nocturnal melatonin (MLT) production by exposure to dim light at night (dLAN), as occurs with night shift work and/or disturbed sleep-wake cycles, is associated with a significantly increased risk of breast cancer and resistance to tamoxifen and doxorubicin. Melatonin inhibition of human breast cancer chemoresistance involves mechanisms including suppression of tumor metabolism and inhibition of kinases and transcription factors which are often activated in drug-resistant breast cancer. Signal transducer and activator of transcription 3 (STAT3), frequently overexpressed and activated in paclitaxel (PTX)-resistant breast cancer, promotes the expression of DNA methyltransferase one (DNMT1) to epigenetically suppress the transcription of tumor suppressor Aplasia Ras homolog one (ARHI) which can sequester STAT3 in the cytoplasm to block PTX resistance. We demonstrate that breast tumor xenografts in rats exposed to dLAN and circadian MLT disrupted express elevated levels of phosphorylated and acetylated STAT3, increased DNMT1, but reduced sirtuin 1 (SIRT1) and ARHI. Furthermore, MLT and/or SIRT1 administration blocked/reversed interleukin 6 (IL-6)-induced acetylation of STAT3 and its methylation of ARH1 to increase ARH1 mRNA expression in MCF-7 breast cancer cells. Finally, analyses of the I-SPY 1 trial demonstrate that elevated MT₁ receptor expression is significantly correlated with pathologic complete response following neo-adjuvant therapy in breast cancer patients. This is the first study to demonstrate circadian disruption of MLT by dLAN driving intrinsic resistance to PTX via epigenetic mechanisms increasing STAT3 expression and that MLT administration can reestablish sensitivity of breast tumors to PTX and drive tumor regression.

Unexpected implications of STAT3 acetylation revealed by genetic encoding of acetyl-lysine

The signal transducer and activator of transcription 3 (STAT3) protein is activated by phosphorylation of a specific tyrosine residue (Tyr705) in response to various extracellular signals. STAT3 activity was also found to be regulated by acetylation of Lys685. However, the molecular mechanism by which Lys685 acetylation affects the transcriptional activity of STAT3 remains elusive. By genetically encoding the co-translational incorporation of acetyl-lysine into position Lys685 and co-expression of STAT3 with the Elk receptor tyrosine kinase, we were able to characterize site-specifically acetylated, and simultaneously acetylated and phosphorylated STAT3. We measured the effect of acetylation on the crystal structure, and DNA binding affinity and specificity of Tyr705-phosphorylated and non-phosphorylated STAT3. In addition, we monitored the deacetylation of acetylated Lys685 by reconstituting the mammalian enzymatic deacetylation reaction in live bacteria. Surprisingly, we found that acetylation, per se, had no effect on the crystal structure, and DNA binding affinity or specificity of STAT3, implying that the previously observed acetylation-dependent transcriptional activity of STAT3 involves an additional cellular component. In addition, we discovered that Tyr705-phosphorylation protects Lys685 from deacetylation in bacteria, providing a new possible explanation for the observed correlation between STAT3 activity and Lys685 acetylation.

Apoptotic or Antiproliferative Activity of Natural Products against Keratinocytes for the Treatment of Psoriasis

Natural products or herbs can be used as an effective therapy for treating psoriasis, an autoimmune skin disease that involves keratinocyte overproliferation. It has been demonstrated that phytomedicine, which is used for psoriasis patients, provides some advantages, including natural sources, a lower risk of adverse effects, and the avoidance of dissatisfaction with conventional therapy. The herbal products’ structural diversity and multiple mechanisms of action have enabled the synergistic activity to mitigate psoriasis. In recent years, the concept of using natural products as antiproliferative agents in psoriasis treatment has attracted increasing attention in basic and clinical investigations. This review highlights the development of an apoptotic or antiproliferatic strategy for natural-product management in the treatment of psoriasis. We systematically introduce the concepts and molecular mechanisms of keratinocyte-proliferation inhibition by crude extracts or natural compounds that were isolated from natural resources, especially plants. Most of these studies focus on evaluation through an in vitro keratinocyte model and an in vivo psoriasis-like animal model. Topical delivery is the major route for the in vivo or clinical administration of these natural products. The potential use of antiproliferative phytomedicine on hyperproliferative keratinocytes suggests a way forward for generating advances in the field of psoriasis therapy.

Abnormal expression of SIRTs in psoriasis: Decreased expression of SIRT 1-5 and increased expression of SIRT 6 and 7

The prevalence of psoriasis is increasing, and poses a serious risk to human health and quality of life. Psoriasis, a chronic immune‑mediated skin disease with epidermal hyperkeratosis and parakeratosis, is associated with numerous complications, including metabolic syndromes that are regulated by sirtuins (SIRTs) via deacetylation. As they serve a necessary function in inflammation and metabolism, SIRTs are considered to link inflammation and metabolic syndrome. Previous studies have indicated that SIRTs serve a function in the pathophysiology of psoriasis, but to date no detailed research has been conducted investigating the expression levels and patterns of SIRTs in psoriasis. The present study investigated the abnormal expression of SIRTs in psoriasis and provided a theoretical foundation for the treatment and prognosis of psoriasis. Tumor necrosis factor (TNF)‑α‑stimulated HaCaT cells and an imiquimod‑induced psoriasis mouse model were used to produce in vitro and in vivo models, respectively. Psoriasis clinical specimens (psoriasis area and severity index >10; n=22) and normal group specimens (n=22) were obtained from human subjects. The mRNA and protein expression levels in human and mouse skin lesions and TNF‑α‑stimulated HaCaT cells were detected using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting, and compared with the control groups. The expression patterns of SIRT proteins were investigated using immunofluorescence (IF) staining. The expression levels of SIRT1, SIRT2, SIRT3, SIRT4 and SIRT5 were downregulated while those of SIRT6 and SIRT7 were upregulated in skin lesions and TNF‑α‑stimulated HaCaT cells compared with the control group as determined by RT‑qPCR, western blotting and IF. Statistically significant differences were observed in vivo and in vitro. P‑values of SIRT1‑7 mRNA are less than 0.05 in RT‑qPCR, and the P‑values of SIRT1‑7 proteins are less than 0.05 except for SIRT4 in the western blot analysis. SIRTs serve notable functions in severe psoriasis dermatitis, with the overexpression of SIRT6 and SIRT7 potentially induced by the adaptive immune response, and the downregulation of SIRT1, SIRT2, SIRT3, SIRT4 and SIRT5 may be a result of an internal environment imbalance in vivo. Psoriasis is an inflammation and metabolism‑associated disease mediated by the SIRT family. The present results provide a novel potential mechanism and strategy for the treatment of psoriasis by modulating the function and expression of SIRTs.

Berberine downregulates CDC6 and inhibits proliferation via targeting JAK-STAT3 signaling in keratinocytes

Psoriasis is a chronic skin disease characterized by hyperproliferation and impaired differentiation of epidermal keratinocytes accompanied by increased inflammation, suggesting that molecules with antiproliferation and anti-inflammatory abilities may be effective for its treatment. One of the key steps in regulating cell proliferation is DNA replication initiation, which relies on prereplication complex (pre-RC) assembly on chromatin. CDC6 is an essential regulator of pre-RC assembly and DNA replication in eukaryotic cells, but its role in proliferation of keratinocytes and psoriasis is unknown. Here we examined CDC6 expression in psoriatic skin and evaluated its function in the proliferation of human keratinocytes. CDC6 expression is upregulated in epidermal cells in psoriatic lesions and it could be induced by IL-22/STAT3 signaling, a key signaling pathway involved in the pathogenesis of psoriasis, in keratinocytes. Depletion of CDC6 leads to decreased proliferation of keratinocytes. We also revealed that berberine (BBR) could inhibit CDK4/6-RB-CDC6 signaling in keratinocytes, leading to reduced proliferation of keratinocytes. The mechanism of antiproliferation effects of BBR is through the repression of JAK1, JAK2, and TYK2, which in turn inhibits activation of STAT3. Finally, we demonstrated that BBR could inhibit imiquimod-induced psoriasis-like skin lesions and upregulation of CDC6 and p-STAT3 in mice. Collectively, our findings indicate that BBR inhibits CDC6 expression and proliferation in human keratinocytes by interfering the JAK–STAT3 signaling pathway. Thus, BBR may serve as a potential therapeutic option for patients with psoriasis.