RIG-I antiviral signaling drives interleukin-23 production and psoriasis-like skin disease

LL37 complexed to double-stranded RNA induces RIG-I-like receptor signalling and Gasdermin E activation facilitating IL-36γ release from keratinocytes

The Interleukin-36 (IL-36) cytokine family have emerged as important players in mounting an inflammatory response at epithelial barriers and tailoring appropriate adaptive immune responses. As members of the Interleukin-1 superfamily, IL-36 cytokines lack a signal peptide for conventional secretion and require extracellular proteolysis to generate bioactive cytokines. Although the IL-36 family plays an important role in the pathogenesis of plaque and pustular psoriasis, little is known about the release mechanisms of these cytokines from keratinocytes and the physiological stimuli involved. Nucleic acid released from damaged or dying keratinocytes initiates early inflammatory signals that result in the breaking of tolerance associated with psoriasis pathogenesis onset. Cathelicidin peptide, LL37 binds to DNA or double-stranded RNA (dsRNA) and activates a type I Interferon responses in plasmacytoid dendritic cells and keratinocytes. Here, we demonstrate that LL37 binds to dsRNA and induces IL-36γ release from human primary keratinocytes. LL37/dsRNA complexes activate RIG-I-like Receptor signalling, resulting in Caspase-3 and Gasdermin E (GSDME) cleavage. Subsequent GSDME pore formation facilitates IL-36γ release. This response is magnified by priming with psoriasis-associated cytokines, IL-17A and IFNγ. IL-36γ release in this manner is largely independent of cell death in primary keratinocytes and lacked extracellular proteolysis of IL-36γ. Conversely, transfection of keratinocytes directly with dsRNA synthetic analogue, Poly(I:C) induces NLRP1 inflammasome activation, which facilitates IL-36γ expression and release in a GSDMD-dependent manner. Inflammasome-associated cell death also enables extracellular processing of IL-36γ by the release of keratinocyte-derived proteases. These data highlight the distinct responses triggered by dsRNA sensors in keratinocytes. Depending on the inflammatory context and magnitude of the exogenous threat, keratinocytes will release IL-36γ coupled with cell death and extracellular cleavage or release the inactive pro-form, which requires subsequent processing by neutrophil proteases to unleash full biological activity, as occurring in psoriatic skin. Cytoplasmic sensing of dsRNA in keratinocytes mediates IL-36γ release via caspase activity and GSDM pore formation Keratinocytes release IL-36γ upon stimulation with intracellular dsRNA alone or complexed to the psoriasis-associated cathelicidin anti-microbial peptide LL37. Left: Transfected dsRNA triggers NLRP1 inflammasome assembly and IL-1β release, which can enhance IL-36γ expression, resulting in IL-36γ release and extracellular cleavage by released proteases. Right: LL37/dsRNA complexes activate a MDA5-MAVS pathway facilitating the release of IL-36γ through Caspase-3 activation and GSDME pore formation.

The Impacts of Seasonal Factors on Psoriasis

Psoriasis is a chronic inflammatory skin condition driven by immune system dysfunction, genetic predisposition and environmental factors. Patients with psoriasis experience a well-known clinical phenomenon of 'winter severity and summer relief', in which seasonal environmental factors play critical roles in the onset and progression of psoriasis. These factors include temperature, humidity, infection, light exposure and psychological stress. Seasonal changes in temperature and humidity can compromise skin barrier function and exacerbate inflammatory responses, thereby worsening psoriasis symptoms. Notably, during the winter, decreased light exposure leads to reduced vitamin D (VD) levels, reaching their lowest levels from late winter to early spring. This decline in VD levels is associated with increased disease activity, greater disease severity and more frequent flare-ups in patients with psoriasis. During the winter, influenza and Streptococcus pneumoniae infections are more prevalent, which can further exacerbate psoriasis symptoms. Moreover, the environmental conditions in winter can trigger or intensify feelings of depression, which may adversely affect psoriasis through the brain-skin axis. In this comprehensive review, we thoroughly examined the influence of seasonal environmental factors on the incidence, recurrence and severity of psoriasis. By clarifying these complex relationships, we aimed to support the future development of more personalised and effective treatment and management strategies for patients with psoriasis.

Innate Immune Sensors and Cell Death-Frontiers Coordinating Homeostasis, Immunity, and Inflammation in Skin

The skin provides a life-sustaining interface between the body and the external environment. A dynamic communication among immune and non-immune cells in the skin is essential to ensure body homeostasis. Dysregulated cellular communication can lead to the manifestation of inflammatory skin conditions. In this review, we will focus on the following two key frontiers in the skin: innate immune sensors and cell death, as well as their cellular crosstalk in the context of skin homeostasis and inflammation. This review will highlight the recent advancements and mechanisms of how these pathways integrate signals and orchestrate skin immunity, focusing on inflammatory skin diseases and skin infections in mice and humans.

Psoriasis Flare Following Paramyxovirus Infection

Psoriasis is a chronic, immunologically mediated disease of multifactorial origin, with genes playing a key role and environmental factors, such as infections, often triggering its onset or exacerbation. While acute streptococcal infections are commonly linked to guttate psoriasis, viral and fungal infections have also been associated with psoriasis flares. We report a case of severe psoriasis exacerbation during viral parotitis caused by paramyxovirus in a 49-year-old male patient with a long-standing psoriasis diagnosis. Following successful treatment with secukinumab, the patient experienced a flare-up coinciding with symptoms of mumps infection. Serological tests confirmed the presence of mumps virus RNA. Secukinumab was discontinued, and treatment with risankizumab resulted in rapid remission of psoriasis. While paramyxovirus infections are not typically associated with psoriasis flares, emerging evidence suggests that dysregulated antiviral immune responses may induce IL-23 production, possibly contributing to inflammation in psoriasis. This case highlights the need for further research on the role of antiviral immune responses in psoriasis exacerbations and the potential therapeutic implications of targeting the IL-23 pathway.

A case of guttate psoriasis after primary herpetic gingivostomatitis

Herpetic gingivostomatitis and anogenital herpes are widely known manifestations of sexually transmitted herpesvirus infections. What is less recognized is the potential causative role of such infections in triggering immune-mediated skin disorders such as guttate psoriasis. We describe the case of a 23-year-old man with an acute episode of guttate psoriasis related to primary herpetic gingivostomatitis. The diagnosis of guttate psoriasis was pathologically confirmed and the condition fully regressed after proper antiviral therapy. This case adds herpes simplex virus to the growing list of pathogens capable of acting as triggers for guttate psoriasis and highlights the need for better insight of the relationship between psoriasis and viral infections.

Single-Cell RNA Sequencing Identifies WARS1+ Mesenchymal Stem Cells with Enhanced Immunomodulatory Capacity and Improved Therapeutic Efficacy

Psoriasis is a common inflammatory skin disorder with no cure. Mesenchymal stem cells (MSCs) have immunomodulatory properties for psoriasis, but the therapeutic efficacies varied, and the molecular mechanisms were unknown. In this study, we improved the efficacy by enhancing the immunomodulatory effects of umbilical cord-derived MSCs (UC-MSCs). UC-MSCs stimulated by TNF-α and IFN-γ exhibited a better therapeutic effect in a mouse model of psoriasis. Single-cell RNA sequencing revealed that the stimulated UC-MSCs overrepresented a subpopulation expressing high tryptophanyl-tRNA synthetase 1 (WARS1). WARS1-overexpressed UC-MSCs treat psoriasis-like skin inflammation more efficiently than control UC-MSCs by restraining the proinflammatory macrophages. Mechanistically, WARS1 maintained a RhoA-Akt axis and governed the immunomodulatory properties of UC-MSCs. Together, we identify WARS1 as a master regulator of UC-MSCs with enhanced immunomodulatory capacities, which paves the way for the directed modification of UC-MSCs for escalated therapeutic efficacy.

Sensory ASIC3 channel exacerbates psoriatic inflammation via a neurogenic pathway in female mice

Psoriasis is an immune-mediated skin disease associated with neurogenic inflammation, but the underlying molecular mechanism remains unclear. We demonstrate here that acid-sensing ion channel 3 (ASIC3) exacerbates psoriatic inflammation through a sensory neurogenic pathway. Global or nociceptor-specific Asic3 knockout (KO) in female mice alleviates imiquimod-induced psoriatic acanthosis and type 17 inflammation to the same extent as nociceptor ablation. However, ASIC3 is dispensable for IL-23-induced psoriatic inflammation that bypasses the need for nociceptors. Mechanistically, ASIC3 activation induces the activity-dependent release of calcitonin gene-related peptide (CGRP) from sensory neurons to promote neurogenic inflammation. Botulinum neurotoxin A and CGRP antagonists prevent sensory neuron-mediated exacerbation of psoriatic inflammation to similar extents as Asic3 KO. In contrast, replenishing CGRP in the skin of Asic3 KO mice restores the inflammatory response. These findings establish sensory ASIC3 as a critical constituent in psoriatic inflammation, and a promising target for neurogenic inflammation management.

Insight into the role of IRF7 in skin and connective tissue diseases

Interferons (IFNs) are signalling proteins primarily involved in initiating innate immune responses against pathogens and promoting the maturation of immune cells. Interferon Regulatory Factor 7 (IRF7) plays a pivotal role in the IFNs signalling pathway. The activation process of IRF7 is incited by exogenous or abnormal nucleic acids, which is followed by the identification via pattern recognition receptors (PRRs) and the ensuing signalling cascades. Upon activation, IRF7 modulates the expression of both IFNs and inflammatory gene regulation. As a multifunctional transcription factor, IRF7 is mainly expressed in immune cells, yet its presence is also detected in keratinocytes, fibroblasts, and various dermal cell types. In these cells, IRF7 is critical for skin immunity, inflammation, and fibrosis. IRF7 dysregulation may lead to autoimmune and inflammatory skin conditions, including systemic scleroderma (SSc), systemic lupus erythematosus (SLE), Atopic dermatitis (AD) and Psoriasis. This comprehensive review aims to extensively elucidate the role of IRF7 and its signalling pathways in immune cells and keratinocytes, highlighting its significance in skin-related and connective tissue diseases.

Retinoic acid-inducible gene-1 knockdown induces immature properties in dendritic cells and prolongs the survival time of allograft mice

BACKGROUND

The mature state of dendritic cells (DCs) determines their ability to regulate immune responses. Retinoic acid-inducible gene-1 (RIG-1) plays a critical role in DC activation and maturation. RIG-1 activation triggers mitogen-activated protein kinase and nuclear factor-kappa B signal transduction. In this study, we aimed to investigate the effects of inhibiting RIG-1 expression in DCs and its potential in inducing immune tolerance.

METHODS

DCs were transduced with the recombinant lentiviral vector (Lv) to inhibit RIG-1 expression. A murine islet and skin transplantation model were constructed to find out whether DC-DDX58-RNAi could prolong allograft survival. The phenotypes of DCs and T-cells were analyzed using flow cytometry. Cytokines in serum were detected by the enzyme-linked immunosorbent assay. Protein levels were determined by Western blot.

RESULTS

RIG-1-deficient DCs had low expression of costimulatory molecules and major histocompatibility complex and a strong phagocytic ability. DC-DDX58-RNAi induced regulatory T cell differentiation in the transplant recipient spleens. The DC-DDX58-RNAi-treated recipients showed satisfactory islet allograft function and longer survival time.

CONCLUSION

Inhibition of RIG-1 with DDX58-RNAi prevented the activation and maturation of the DCs, affected T cell differentiation, protected the biological function of the allograft, and prolonged graft survival. These findings may have important therapeutic implications for new immunomodulatory regimens.

Psoriasis may increase the risk of idiopathic pulmonary fibrosis: a two-sample Mendelian randomization study

BACKGROUND

Although some studies have indicated that Psoriasis could contribute to the risk of idiopathic pulmonary fibrosis (IPF), no study has reported a clear causal association between them. Our aim was to explore the potential relationship between Psoriasis and IPF using Mendelian randomization (MR) design.

METHODS

To explore a causal association between Psoriasis and IPF, we used genetic instruments from the largest available genome-wide association study (GWAS) of European ancestry, including psoriasis (5314 cases, 457,619 controls) and IPF (1028 cases, 196,986 controls). Our main analyses were conducted by inverse-variance weighted (IVW) method with random-effects model, with the other complementary four analyses: weighted median method, weighted mode, multivariable MR and MR-Egger approach.

RESULTS

The results of IVW methods demonstrated that genetically predicted psoriasis was significantly associated with higher odds of IPF, with an odds ratio (OR) of 1.09 (95%CI, 1.01-1.18; P = 0.02). Weighted median method, weighted mode and multivariable MR also demonstrated directionally similar results (P < 0.05), while the MR-Egger regression did not reveal the impact of psoriasis on IPF (OR = 1.09, 95%CI, 0.98-1.21; P = 0.11). In addition, both funnel plots and MR-Egger intercepts indicated no directional pleiotropic effects between psoriasis and IPF.

CONCLUSIONS

Our study provided potential evidence between genetically predicted psoriasis and IPF, which suggests that understanding the mutual risk factors between psoriasis and IPF can facilitate the clinical management of both diseases.

Transcription Factor IRF7 is Involved in Psoriasis Development and Response to Guselkumab Treatment

Purpose

Guselkumab is a highly effective biologic agent for treating psoriasis. This study aimed to explore potential transcription factors involved in psoriasis pathogenesis and response to guselkumab treatment, aiming to provide new therapeutic strategies for psoriasis.

Patients and Methods

We analyzed gene expression and single-cell RNA-seq data from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) that upregulated in psoriasis and downregulated after guselkumab treatment were subjected to enrichment analyses. Single-cell regulatory network inference and clustering (SENIC) and regulon module analyses identified different regulon activities between the lesion and non-lesion skin of psoriasis. Cell-cell communication analysis revealed interactions among specific cell clusters. Transcription factor (TF) regulons were identified from the guselkumab-specific regulon network. Gene set enrichment analysis (GSEA) confirmed the IRF7 regulon in the validation cohort. Finally, the expression level of IRF7 was identified in plaque psoriasis before and after 12 weeks of guselkumab therapy by immunohistochemical experiment.

Results

799 DEGs were downregulated after guselkumab treatment. Enrichment analyses highlighted the interleukin-17 (IL-17) pathway in this gene set. The M2 module exhibited the primary difference in regulon activity. Strong cell-cell interactions were observed between keratinocytes and immune cells. IRF7 regulon had significant roles in psoriasis and treatment response, as validated by GSEA analysis using the IL-17 signaling pathway as a reference. The immunohistochemical analysis unveiled substantial differences in the expression levels of IRF7 in psoriatic skin samples before and after 12 weeks of guselkumab treatment.

Conclusion

IRF7 may be the key player in psoriasis pathogenesis and the therapeutic process involving guselkumab. Targeting IRF7 might offer new therapeutic strategies for psoriasis.

Triggers for the onset and recurrence of psoriasis: a review and update

Psoriasis is an immune-mediated inflammatory skin disease, involving a complex interplay between genetic and environmental factors. Previous studies have demonstrated that genetic factors play a major role in the pathogenesis of psoriasis. However, non-genetic factors are also necessary to trigger the onset and recurrence of psoriasis in genetically predisposed individuals, which include infections, microbiota dysbiosis of the skin and gut, dysregulated lipid metabolism, dysregulated sex hormones, and mental illness. Psoriasis can also be induced by other environmental triggers, such as skin trauma, unhealthy lifestyles, and medications. Understanding how these triggers play a role in the onset and recurrence of psoriasis provides insights into psoriasis pathogenesis, as well as better clinical administration. In this review, we summarize the triggers for the onset and recurrence of psoriasis and update the current evidence on the underlying mechanism of how these factors elicit the disease. Video Abstract.

The opposite effect of tapinarof between IMQ and IL-23 induced psoriasis mouse models

Tapinarof is an aryl hydrocarbon receptor (AHR) ligand which is used to treat plaque psoriasis in adults. However, the underlying mechanism is not yet fully understood. In this study, we applied two of the most studied psoriasis mouse models: topical application of imiquimod (IMQ) and subcutaneous injection of IL-23. Although both models successfully induced psoriasis-like lesions in mice, tapinarof had a completely opposite effect on the two models. Tapinarof decreased the expression of multiple essential cytokines involved in the pathological IL-23/IL-17/IL-22 axis and ameliorated IMQ-induced psoriatic dermatitis, inhibiting keratinocyte proliferation and abnormal differentiation. However, in the IL-23-injection-model, tapinarof instead aggravated the disease. Here, tapinarof increased epidermal thickness and differentiated epidermal dysplasia in mice. Our data suggest that tapinarof may have different effects on varied types of psoriasis.

The Renin-Angiotensin System: The Challenge behind Autoimmune Dermatological Diseases

Autoimmune dermatological diseases (AIDD) encompass a diverse group of disorders characterized by aberrant immune responses targeting the skin and its associated structures. In recent years, emerging evidence suggests a potential involvement of the renin-angiotensin system (RAS) in the pathogenesis and progression of these conditions. RAS is a multicomponent cascade, primarily known for its role in regulating blood pressure and fluid balance. All of the RAS components play an important role in controlling inflammation and other immune responses. Angiotensin II, the main effector, acts on two essential receptors: Angiotensin Receptor 1 and 2 (AT1R and AT2R). A disturbance in the axis can lead to many pathological processes, including autoimmune (AI) diseases. AT1R activation triggers diverse signaling cascades involved in inflammation, fibrosis and tissue remodeling. Experimental studies have demonstrated the presence of AT1R in various cutaneous cells and immune cells, further emphasizing its potential contribution to the AI processes in the skin. Furthermore, recent investigations have highlighted the role of other RAS components, beyond angiotensin-converting enzyme (ACE) and Ang II, that may contribute to the pathophysiology of AIDD. Alternative pathways involving ACE2, Ang receptors and Ang-(1-7) have been implicated in regulating immune responses and tissue homeostasis within the skin microenvironment. Understanding the intricate involvement of the RAS in AIDD may provide novel therapeutic opportunities. Targeting specific components of the RAS, such as angiotensin receptor blockers (ARBs), ACE inhibitors (ACEIs) or alternative RAS pathway modulators, could potentially ameliorate inflammatory responses, reduce tissue damage and lessen disease manifestations. Further research is warranted to outline the exact mechanisms underlying RAS-mediated immune dysregulation in AIDD. This abstract aims to provide a concise overview of the intricate interplay between the RAS and AIDD. Therefore, we elaborate a systematic review of the potential challenge of RAS in the AIDD, including psoriasis, systemic sclerosis, vitiligo, lupus erythematosus and many more.

The IFIH1/MDA5 rs1990760 Gene Variant (946Thr) Differentiates Early- vs. Late-Onset Skin Disease and Increases the Risk of Arthritis in a Spanish Cohort of Psoriasis

The melanoma differentiation-associated protein 5 (MDA5; encoded by the IFIH1 gene) mediates the activation of the interferon pathway in response to a viral infection. This protein is also upregulated in autoimmune diseases and psoriasis skin lesions. IFIH1 gene variants that increase MDA5 activity have been associated with an increased risk for immune-mediated diseases, including psoriasis. Our aim is to determine the association between three IFIH1 variants (rs35337543 G/C, intron8 + 1; rs35744605 C/A, Glu627Stop; and rs1990760 C/T, Ala946Thr) and the main clinical findings in a cohort of Spanish patients with psoriasis (N = 572; 77% early-onset). Early-onset psoriasis patients (EOPs) had a significantly higher frequency of severe disease and the Cw6*0602 allele. Carriers of rs1990760 T (946Thr) were more common in the EOPs (p < 0.001), and the effect was more pronounced among Cw6*0602-negatives. This variant was also associated with an increased risk of psoriatic arthritis (PsA) independent from other factors (OR = 1.62, 95%CI = 1.11-2.37). The rs3533754 and rs35744605 polymorphisms did not show significant differences between the two onset age or PsA groups. Compared to the controls, the 946Thr variant was more common in the EOPs (nonsignificant difference) and significantly less common in patients aged >40 years (p = 0.005). In conclusion, the common IFIH1 rs1990760 T allele was significantly more frequent in early-onset compared to late-onset patients. This variant was also an independent risk factor for PsA in our cohort. Our study reinforces the widely reported role of the IFIH1 gene variants on psoriatic disease.

Bioinformatics analysis to reveal the potential comorbidity mechanism in psoriasis and nonalcoholic steatohepatitis

PURPOSE

An increasing amount of evidence suggests that psoriasis and nonalcoholic steatohepatitis (NASH) may occur simultaneously, whereas the underlying mechanisms remain unclear. Our research aims to explore the potential comorbidity mechanism in psoriasis and nonalcoholic steatohepatitis.

MATERIALS AND METHODS

The expression profiles of psoriasis (GSE30999, GSE13355) and NASH (GSE24807, GSE17470) were downloaded from GEO datasets. Next, common differently expressed genes (DEGs) of psoriasis and NASH were investigated. Then, GO and KEGG enrichment, protein interaction network (PPI) construction, and hub gene identification for DEGs were performed. Finally, immune cells expression, target genes predicted by common miRNAs, and transcription factors interaction analysis for hub genes were carried out.

RESULTS

Twenty DEGs were identified in totally. GO analysis revealed response to the virus was the most enriched term, and hepatitis C and coronavirus disease-COVID-19 infection-associated pathways were mainly enriched in KEGG. A total of eight hub genes were collected, including IFIT1, IFIT3, OAS1, HPGDS, IFI27, IFI44, CXCL10, IRF9, and 11 TFs were predicted. Then, neutrophils and monocytes were identified as immune cells that express the most hub genes. Moreover, five common miRNAs for psoriasis and NASH and one common miRNAs (hsa-miR-1305)-mRNAs (CHL1, MBNL2) network were presented.

CONCLUSION

CHL1 and MBNL2 may participate in the process of psoriasis and NASH via regulating hsa-miR-1305, and together with eight hub genes may be potential therapeutic targets for future treatment for the co-occurrence of these two diseases. This comprehensive bioinformatic analysis provides new insights on molecular pathogenesis and identification of potential therapeutic targets for the co-occurrence of them.

Insights into Nutritional Strategies in Psoriasis

Psoriasis, an autoimmune chronic inflammatory skin condition, has a high incidence in the general population, reaching 2-4%. Its pathogenesis involves an interplay of genetic factors, immune disturbances, and environmental factors. Within the environmental factors that aid the appearance of this autoimmune skin disease, the Western lifestyle and overall diet play important roles in the steady growth in psoriasis prevalence. Furthermore, psoriasis is associated with comorbidities such as psoriatic arthritis, cardiovascular disease, metabolic syndrome, and obesity. Accumulating evidence suggests that obesity is an important risk factor for psoriasis. Moreover, obesity aggravates established psoriasis, and a reduction in the body mass index can improve the clinical outcomes of psoriasis and increase the efficacy of standard psoriasis therapies. The possible connection between this autoimmune disease and obesity relies on the fact that white adipose tissue is an essential endocrine organ that secretes an array of immune mediators and inflammatory and metabolic factors with pro-inflammatory action. Thus, immune-mediated mechanisms in both psoriasis and obesity conditions are common factors. This paper describes the factors that link obesity with skin autoimmune disease and highlights the importance of the stimulatory or regulatory effects of nutrients and food in psoriasis and the possible improvement of psoriasis through nutritional strategies.

RIG-I contributes to keratinocyte proliferation and wound repair by inducing TIMP-1 expression through NF-κB signaling pathway

Epithelial keratinocyte proliferation is an essential element of wound repair, and chronic wound conditions, such as diabetic foot, are characterized by aberrant re-epithelialization. In this study, we examined the functional role of retinoic acid inducible-gene I (RIG-I), a key regulator of epidermal keratinocyte proliferation, in promoting TIMP-1 expression. We found that RIG-I is overexpressed in keratinocytes of skin injury and underexpressed in skin wound sites of diabetic foot and streptozotocin-induced diabetic mice. Moreover, mice lacking RIG-I developed an aggravated phenotype when subjected to skin injury. Mechanistically, RIG-I promoted keratinocyte proliferation and wound repair by inducing TIMP-1 via the NF-κB signaling pathway. Indeed, recombinant TIMP-1 directly accelerated HaCaT cell proliferation in vitro and promoted wound healing in Ddx58-/- and diabetic mice in vivo. In summary, we demonstrated that RIG-I is a crucial factor that mediates epidermal keratinocyte proliferation and may be a potential biomarker for skin injury severity, thus making it an attractive locally therapeutic target for the treatment of chronic wounds such as diabetic foot.

LncRNA UCA1 promotes keratinocyte-driven inflammation via suppressing METTL14 and activating the HIF-1α/NF-κB axis in psoriasis

Keratinocytes are closely associated with innate immunity and inflammatory responses, and are dysregulated during the development of psoriasis, but the underlying mechanisms are not yet fully understood. This work aims to reveal the effects of long non-coding RNA (lncRNA) UCA1 in psoriatic keratinocytes. UCA1 was identified as a psoriasis-related lncRNA that highly expressed in psoriatic lesions. The transcriptome and proteome data of keratinocyte cell line HaCaT showed that UCA1 could positively regulate inflammatory functions, such as response to cytokine. Furthermore, UCA1 silencing decreased inflammatory cytokine secretion and innate immunity gene expression in HaCaT, its culture supernatant also decreased the migration and tube formation ability of vascular endothelial cells (HUVECs). Mechanistically, UCA1 activated the NF-κB signaling pathway, which is regulated by HIF-1α and STAT3. We also observed a direct interaction between UCA1 and N6-methyladenosine (m⁶A) methyltransferase METTL14. Knocking down METTL14 counteracted the effects of UCA1 silencing, indicating that it can suppress inflammation. In addition, the levels of m⁶A-modified HIF-1α were decreased in psoriatic lesions, indicating that HIF-1α is a potential target of METTL14. Taken together, this work indicates that UCA1 positively regulates keratinocyte-driven inflammation and psoriasis development by binding to METTL14, and activating HIF-1α and NF-κB signaling pathway. Our findings provide new insights into the molecular mechanisms of keratinocyte-driven inflammation in psoriasis.

Inducible nitric oxide synthase-expressing myeloid-derived suppressor cells regulated by interleukin 35 contribute to the pathogenesis of psoriasis

Although psoriasis is classified as a T cell-mediated inflammatory disease, the contribution of myeloid cells to the pathogenesis of psoriasis is not fully understood. In the present study, we demonstrated that the expression of the anti-inflammatory cytokine interleukin-35 (IL-35) was significantly increased in patients with psoriasis with a marked increase in the number of myeloid-derived suppressor cells (MDSCs). Similar results were obtained in an imiquimod-induced psoriasis mouse model. IL-35 reduced the total number of MDSCs and their subtypes in the spleens and psoriatic skin lesions, ameliorating psoriasis. IL-35 also reduced the expression of inducible nitric oxide synthase in MDSCs, although it had no significant effect on interleukin-10 expression. Adoptive transfer of MDSCs from imiquimod-challenged mice aggravated the disease and weakened the effect of IL-35 in the recipient mice. In addition, mice transferred with MDSCs isolated from inducible nitric oxide synthase knockout mice had milder disease than those with wild-type MDSCs. Furthermore, wild-type MDSCs reversed the effects of IL-35, while MDSCs isolated from inducible nitric oxide synthase knockout mice did not affect IL-35 treatment. In summary, IL-35 may play a critical role in the regulation of iNOS-expressing MDSCs in the pathogenesis of psoriasis, highlighting IL-35 as a novel therapeutic strategy for patients with chronic psoriasis or other cutaneous inflammatory diseases.

Characterization of immune landscape and development of a novel N7-methylguanine-related gene signature to aid therapy in recurrent aphthous stomatitis

OBJECTIVES

Recurrent aphthous stomatitis (RAS) is the most common inflammatory disease of the oral mucosa resulting in an impaired life quality and even leading to tumors in susceptible populations. N7-Methylguanine (m7G) plays a vital role in various cellular activities but has not yet been investigated in RAS. We aimed at picturing the immune landscape and constructing an m7G-related gene signature, and investigating candidate drugs and gene-disease association to aid therapy for RAS.

METHODS

For our study, m7G-related differentially expressed genes (DEGs) were screened. We outlined the immune microenvironment and studied the correlations between the m7G-related DEGs and immune cells/pathways. We performed functional enrichment analyses and constructed the protein-protein interaction (PPI) and multifactor regulatory network in RAS. The m7G-related hub genes were extracted to formulate the corresponding m7G predictive signature.

RESULTS

We obtained 11 m7G-related DEGs and studied a comprehensive immune infiltration landscape, which indicated several immune markers as possible immunotherapeutic targets. The PPI and multifactor regulatory network was constructed and 4 hub genes (DDX58, IFI27, IFIT5, and PML) were identified, followed by validation of the corresponding m7G predictive signature for RAS. GO and KEGG analyses revealed the participation of JAK-STAT and several immune-related pathways. Finally, we suggested candidate drugs and gene-disease associations for potential RAS medical interventions.

CONCLUSIONS

The present study pictured a comprehensive immune infiltration landscape and suggested that m7G played a vital role in RAS through immune-related pathways. This study provided new insight for the future investigation of the mechanisms and therapeutic strategies for RAS.

Intravenous As2O3 as a promising treatment for psoriasis - an experimental study in psoriasis-like mouse model

OBJECTIVE

To evaluate the efficacy and mechanistic bases of the intravenous injection of arsenic trioxide at clinical-relevant doses for treating an imiquimod-induced psoriasis-like mouse model.

METHODS

After inducing psoriasis-like skin lesions on the back of mice with imiquimod, mice in each group were injected with a clinical dose of arsenic trioxide through the tail vein. The changes in the gene expression, protein expression and distribution of relevant inflammatory factors were evaluated in the inflicted skin area, for mechanisms underlying the efficacy of intravenous As₂O₃ intervention. HaCaT cells were used to establish an in vitro psoriasis model and pcDNA3.1-NF-κB overexpression plasmid was transfected into cells to overexpress P65, which further confirmed the role of the NF-κB signaling pathway in the effectiveness of As₂O₃.

RESULTS

Clinical dose of As₂O₃ can significantly improve abnormal symptoms and pathological changes in psoriasis-like skin lesions induced by IMQ in mice. While IMQ induced abnormal expression and distribution of inflammatory factors in the RIG-I pathway and the microRNA-31 (miR-31) pathway in psoriatic skin tissues, intravenous As₂O₃ can effectively regulate and restore the normality. The leading role of NF-κB signaling was evidenced in vivo and validated in vitro using the NF-κB-overexpressed HaCaT cell model.

CONCLUSION

Clinical dosage of As₂O₃ may achieve effective treatment of IMQ-induced psoriatic skin lesions by modulating the NF-κB signaling pathway which regulates both the RIG-I and the miR-31 lines of action. Our data provided strong evidence supporting the claim that systemic As₂O₃ administration of clinical doses can be a promising treatment for psoriasis patients.

Single-Cell RNA Sequencing Reveals the Immune Cell Profiling in IMQ Induced Psoriasis-Like Model

PURPOSE

Psoriasis is a chronic systemic inflammatory skin disease with a high recurrence rate. The immune response plays an important role in psoriasis. However, the subsets of immune cells involved in inflammation in psoriatic mice have not been fully studied. This study showed the immune environment characteristics of psoriasis in mice.

METHODS

We used single-cell RNA sequencing (10× Genomics) as an unbiased analytical strategy to investigate the heterogeneity of skin immune cells in imiquimod-induced psoriasis mice systematically.

RESULTS

We identified 10 major clusters and their marker genes among 14,439 cells. The proportions of macrophages, NK/T cells, conventional dendritic cells (cDCs) and plasmacytoid dendritic cells (pDCs) were increased in psoriatic mice. Macrophages were the largest group and were further divided into 7 subgroups, and all macrophage clusters were increased in psoriatic mice. Differentially expressed genes in control versus psoriatic mice skin lesions showed that Fcgr4, Saa3 and Acp5 in macrophages, Acp5, Fcgr4 and Ms4a6d in NK/T cells, Saa3 in cDCs, and Ifitm1 in pDCs were upregulated in psoriasis mice. Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis emphasized the role of oxidative phosphorylation signals and antigen processing and presentation signals in murine psoriasis-like models.

CONCLUSION

Our study reveals the immune environment characteristics of the commonly used IMQ induced psoriasis-like models and provides a systematic insight into the immune response of mice with psoriasis, which is conducive to comparing the similarities and differences between the mouse model and human psoriasis.

Roles of Infection in Psoriasis

Psoriasis is a chronic, immune-mediated disorder with cutaneous and systemic manifestations. Genetic predisposition, environmental factors, and immune dysfunction all contribute to the pathogenesis of psoriasis with host-microbe interaction governing the progression of this disease. Emerging evidence has indicated that infection is an environmental trigger for psoriasis and plays multiple roles in its maintenance as evidenced by the frequent association between guttate psoriasis onset and acute streptococcal infection. Different infectious factors act on immune cells to produce inflammatory cytokines that can induce or aggravate psoriasis. In addition to bacterial infections, viral and fungal infections have also been shown to be strongly associated with the onset or exacerbation of psoriasis. Intervention of skin microbiota to treat psoriasis has become a hot research topic. In this review, we summarize the effects of different infectious factors (bacteria, viruses, and fungi) on psoriasis, thereby providing insights into the manipulation of pathogens to allow for the identification of improved therapeutic options for the treatment of this condition.

Mouse Models of Psoriasis: A Comprehensive Review

The use of preclinical animal models of psoriasis has significantly increased over the last three decades, with each model having unique strengths and limitations. Some models translate better to human disease, and many have provided unique insight into psoriasis disease pathogenesis. In this comprehensive review, we present a comparative description and discussion of genetic mouse models, xenograft approaches, and elicited methods using cytokine injections into and topical imiquimod onto mice. We provide an inclusive list of genetically modified animals that have had imiquimod applied to or cytokines injected into their skin and describe the outcomes of these manipulations. This review will provide a valuable resource for those interested in working with psoriasis animal models.

Allosteric inhibition of SHP2 uncovers aberrant TLR7 trafficking in aggravating psoriasis

Psoriasis is a complex chronic inflammatory skin disease with unclear molecular mechanisms. We found that the Src homology‐2 domain‐containing protein tyrosine phosphatase‐2 (SHP2) was highly expressed in both psoriatic patients and imiquimod (IMQ)‐induced psoriasis‐like mice. Also, the SHP2 allosteric inhibitor SHP099 reduced pro‐inflammatory cytokine expression in PBMCs taken from psoriatic patients. Consistently, SHP099 significantly ameliorated IMQ‐triggered skin inflammation in mice. Single‐cell RNA sequencing of murine skin demonstrated that SHP2 inhibition impaired skin inflammation in myeloid cells, especially macrophages. Furthermore, IMQ‐induced psoriasis‐like skin inflammation was significantly alleviated in myeloid cells (monocytes, mature macrophages, and granulocytes)—but not dendritic cells conditional SHP2 knockout mice. Mechanistically, SHP2 promoted the trafficking of toll‐like receptor 7 (TLR7) from the Golgi to the endosome in macrophages by dephosphorylating TLR7 at Tyr1024, boosting the ubiquitination of TLR7 and NF‐κB‐mediated skin inflammation. Importantly, Tlr7 point‐mutant knock‐in mice showed an attenuated psoriasis‐like phenotype compared to wild‐type littermates following IMQ treatment. Collectively, our findings identify SHP2 as a novel regulator of psoriasis and suggest that SHP2 inhibition may be a promising therapeutic approach for psoriatic patients.

NF-κB1 Contributes to Imiquimod-Induced Psoriasis-Like Skin Inflammation by Inducing Vγ4+Vδ4+γδT17 Cells

Recent studies have identified NF-κB1 as a new disease susceptibility gene for psoriasis. Although accumulating evidence has shown the importance of NF-κB signaling in various cell types in the pathogenesis of psoriasis, it remains unclear how NF-κB1 contributes to the pathogenesis of psoriasis. In this study, we examined psoriasis-like skin diseases induced by topical administration of imiquimod in Nf-κb1‒deficient (Nf-κb1^-/-) mice and littermate wild-type (WT) mice. Compared with WT mice, Nf-κb1^-/- mice exhibited attenuated skin inflammation. The numbers of Vγ4⁺Vδ4⁺γδT17 cells, which cause skin inflammation in this model, were significantly reduced in the skin and draining lymph nodes in imiquimod-treated Nf-κb1^-/- mice. Nf-κb1 is preferentially phosphorylated in Vγ4⁺Vδ4⁺γδT17 cells in WT mice. In vitro proliferation of Vγ4⁺Vδ4⁺γδT17 cells but not conventional CD4⁺ T cells was significantly impaired in Nf-κb1^-/- mice compared with that in WT mice. RNA-sequencing analyses revealed that the expression of E2 factor target genes was decreased in Vγ4⁺Vδ4⁺γδT cells by the absence of NF-κB1. Consistently, the cell cycle progression of Vγ4⁺Vδ4⁺γδT cells was reduced in Nf-κb1^-/- mice compared with that in WT mice. These results suggest that Nf-κb1 plays a crucial role in the pathogenesis of imiquimod-induced psoriasis-like skin inflammation by promoting the proliferation of Vγ4⁺Vδ4⁺γδT17 cells.

Novel archetype in psoriasis management bridging molecular dynamics in exploring novel therapies

Psoriasis is an autoimmune chronic inflammatory condition of skin affecting 125 million populaces around the globe. It is implicated as a result of multifaceted phenomena involving various cell and subcell activities with the aid of numerous cellular and molecular components including signaling aisle and regulatory proteins owing to the development of such hyperproliferative dermatological conditions. This involves a deeply complex and conflicting pathology owing to genetic and immunological deviations resulting from the unusual presentation of different signaling pathways and regulatory proteins. Explorations of these biomarkers and intervention of molecular and cellular processes in psoriasis are yet to be investigated and could be an exceptional aspect for understanding pathology with successful targeting of disease. In the presented study, we have integrated molecular insights, including signaling molecules, pathways, and proteins implicated in pathogenesis, and we have attempted to link this knowledge to the targeting of these phenomena in order to manage the conditions precisely. Further, therapeutic delivery approaches for targeting distinct layers of skin have also been investigated based on the application of different nanocarriers for successful psoriasis treatment.

Psoriatic skin inflammation is promoted by c-Jun/AP-1-dependent CCL2 and IL-23 expression in dendritic cells

Toll-like receptor (TLR) stimulation induces innate immune responses involved in many inflammatory disorders including psoriasis. Although activation of the AP-1 transcription factor complex is common in TLR signaling, the specific involvement and induced targets remain poorly understood. Here, we investigated the role of c-Jun/AP-1 protein in skin inflammation following TLR7 activation using human psoriatic skin, dendritic cells (DC), and genetically engineered mouse models. We show that c-Jun regulates CCL2 production in DCs leading to impaired recruitment of plasmacytoid DCs to inflamed skin after treatment with the TLR7/8 agonist Imiquimod. Furthermore, deletion of c-Jun in DCs or chemical blockade of JNK/c-Jun signaling ameliorates psoriasis-like skin inflammation by reducing IL-23 production in DCs. Importantly, the control of IL-23 and CCL2 by c-Jun is most pronounced in murine type-2 DCs. CCL2 and IL-23 expression co-localize with c-Jun in type-2/inflammatory DCs in human psoriatic skin and JNK-AP-1 inhibition reduces the expression of these targets in TLR7/8-stimulated human DCs. Therefore, c-Jun/AP-1 is a central driver of TLR7-induced immune responses by DCs and JNK/c-Jun a potential therapeutic target in psoriasis.

HLA-Cw6 and other HLA-C alleles, as well as MICB-DT, DDX58, and TYK2 genetic variants associate with optimal response to anti-IL-17A treatment in patients with psoriasis

Objective: Our pharmacogenomic study evaluated the influence of the presence/absence of genetic variants of psoriasis-risk loci on the clinical response to secukinumab. Differences in the single-nucleotide polymorphism (SNP) pattern characterizing HLA-Cw6+ or HLA-Cw6- patient subpopulations, showing high or low responses to secukinumab, were also analyzed. Methods: 417 SNPs were analyzed by Next-Generation Sequencing technology, in a cohort of 62 psoriatic patients and undergone secukinumab treatment. Univariate regression analysis was employed to examine the association between SNP and clinical response to secukinumab. Multivariate analysis was also performed to assess multivariate differences in SNP pattern of HLA-Cw6+ or HLA-Cw6- patients showing high or low responses to secukinumab. Results: Eight SNPs in HLA-C and upstream region (rs13207315, rs6900444, rs12189871, rs12191877, rs4406273, and rs10484554), including HLA-Cw6 classical allele (rs1131118), and three in MICB-DT (rs9267325), DDX58 (rs34085293) and TYK2 (rs2304255) genes, associating with excellent response to secukinumab were identified. Importantly, rs34085293 or rs2304255 SNP status defined a subgroup of super-responder patients. We also found that HLA-Cw6+ and HLA-Cw6- patients carried out specific patterns of SNPs associating with different responses to secukinumab. Conclusion: Assessment of HLA-Cw6, together with other allelic variants of genes, could be helpful to define patients which better benefit from anti-IL-17 therapy. Abbreviations: PASI: Psoriasis Area and Severity Index; SNP: Single-Nucleotide Polymorphism Rs: Reference SNP; PASI75: 75% reduction in Psoriasis Area and Severity Index; PASI90: 90% reduction in Psoriasis Area and Severity Index; PASI100: 100% reduction in Psoriasis Area and Severity Index; NGS: Next-Generation Sequencing; OR: Odds Ratio; CAP: Canonical Analysis of Principal coordinates; BMI: Body Mass Index; LD: Linkage Disequilibrium.

Illuminating the Role of Vitamin A in Skin Innate Immunity and the Skin Microbiome: A Narrative Review

Vitamin A is a fat-soluble vitamin that plays an important role in skin immunity. Deficiencies in Vitamin A have been linked to impaired immune response and increased susceptibility to skin infections and inflammatory skin disease. This narrative review summarizes recent primary evidence that elucidates the role of vitamin A and its derivatives on innate immune regulators through mechanisms that promote skin immunity and sustain the skin microbiome.

The Role of Cutaneous Type I IFNs in Autoimmune and Autoinflammatory Diseases

IFNs are well known as mediators of the antimicrobial response but also serve as important immunomodulatory cytokines in autoimmune and autoinflammatory diseases. An increasingly critical role for IFNs in evolution of skin inflammation in these patients has been recognized. IFNs are produced not only by infiltrating immune but also resident skin cells, with increased baseline IFN production priming for inflammatory cell activation, immune response amplification, and development of skin lesions. The IFN response differs by cell type and host factors and may be modified by other inflammatory pathway activation specific to individual diseases, leading to differing clinical phenotypes. Understanding the contribution of IFNs to skin and systemic disease pathogenesis is key to development of new therapeutics and improved patient outcomes. In this review, we summarize the immunomodulatory role of IFNs in skin, with a focus on type I, and provide insight into IFN dysregulation in autoimmune and autoinflammatory diseases.

Psoriasis-like skin disorder in transgenic mice expressing a RIG-I Singleton-Merten syndrome variant

Mutations in DDX58 (DExD/H-box helicase 58), which encodes the cytoplasmic RNA sensor retinoic acid-inducible gene I (RIG-I), were recently identified in the rare autoimmune disease Singleton-Merten syndrome (SMS). We report the spontaneous development of psoriasis-like skin lesions as an SMS-like symptom in transgenic mice harboring one of the RIG-I SMS variants, E373A. Histological analysis revealed typical characteristics of psoriasis, including the abnormal proliferation and differentiation of keratinocytes leading to epidermal hyperplasia, and infiltrates consisting of neutrophils, dendritic cells and T cells. Levels of the IL-23/IL-17 immune axis cytokines were high in the skin lesions. Rag2-/- transgenic mice showed partial amelioration of the phenotype, with down-regulation of inflammatory cytokines, including IL-17A, suggesting the importance of lymphocytes for the pathogenesis similar to that of human psoriasis. Of note, IL-17A deficiency abolished the skin phenotype, and treatment using the JAK inhibitor tofacitinib not only prevented onset, but also improved the skin manifestations even after onset. Our study provides further evidence for the involvement of RIG-I activation in the onset and progression of psoriasis via type I interferon signaling and the IL-23/IL-17 axis.

The influence of interferon on healthy and diseased skin

Type I interferons (IFNs) are an immunomodulatory class of cytokines that serve to protect against viral and bacterial infection. In addition, mounting evidence suggests IFNs, particularly type I but also IFNγ, are important to the pathogenesis of autoimmune and inflammatory skin diseases, such as cutaneous lupus erythematosus (CLE). Understanding the role of IFNs is relevant to anti-viral responses in the skin, skin biology, and therapeutics for these IFN-related conditions. Type I IFNs (α and β) are produced by recruited inflammatory cells and by the epidermis itself (IFNκ) and have important roles in autoimmune and inflammatory skin disease. Here, we review the current literature utilizing a PubMed database search using terms [interferon/IFN/type I IFN AND lupus/ cutaneous lupus/CLE/dermatomyositis/Sjogrens/psoriasis/lichen planus/morphea/alopecia areata/vitiligo] with a focus on the role of IFNs in basic keratinocyte biology and their implications in the cutaneous autoimmune and inflammatory diseases: cutaneous lupus erythematosus, dermatomyositis, Sjogren's syndrome, psoriasis, lichen planus, alopecia areata and vitiligo. We provide information about genes and proteins induced by IFNs and how downstream mechanisms relate to clinical disease.

Targeting Myeloid-Derived Suppressor Cells Is a Novel Strategy for Anti-Psoriasis Therapy

Psoriasis is a common immune-mediated, chronic inflammatory genetic-related disease that affects patients' quality of life. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of progenitor and immature myeloid cells which are expanded in psoriatic skin lesions and peripheral blood. However, the role of MDSCs in the pathogenesis of psoriasis remains unclear. Here, we confirmed that the accumulation of human MDSCs is remarkably increased in skin lesions of psoriasis patients by flow cytometry. Depleting MDSCs by Gemcitabine significantly suppresses IMQ-induced psoriatic inflammation and epidermal thickening as well as Th17 and Treg cell accumulation. Moreover, through the RNA-Seq technique, we validated some differentially expressed genes on CD4⁺ T-cells of IMQ-induced-MDSC-depleted mice such as IL-21 and Timd2, which are involved in Th17-cell differentiation or T-cell activation. Interestingly, neutralizing IL-21R by antibody reduces IMQ-induced epidermal thickening through downregulating the infiltration of MDSCs and Th17 cells. Our data suggest that targeting myeloid-derived suppressor cells is a novel strategy for antipsoriasis therapy. IL-21 may be a potential therapeutic target in psoriasis.

Intracellular virus sensor MDA5 exacerbates vitiligo by inducing the secretion of chemokines in keratinocytes under virus invasion

Vitiligo is a disfiguring disease featuring chemokines-mediated cutaneous infiltration of autoreactive CD8+ T cells that kill melanocytes. Copious studies have indicated that virus invasion participates in the pathogenesis of vitiligo. IFIH1, encoding MDA5 which is an intracellular virus sensor, has been identified as a vitiligo susceptibility gene. However, the specific role of MDA5 in melanocyte death under virus invasion is not clear. In this study, we first showed that the expression of anti-CMV IgM and MDA5 was higher in vitiligo patients than healthy controls. Then, by using Poly(I:C) to imitate virus invasion, we clarified that virus invasion significantly activated MDA5 and further potentiated the keratinocyte-derived CXCL10 and CXCL16 which are the two vital chemokines for the cutaneous infiltration of CD8+ T cells in vitiligo. More importantly, IFN-β mediated by the MDA5-MAVS-NF-κB/IRF3 signaling pathway orchestrated the secretion of CXCL10 via the JAK1-STAT1 pathway and MDA5-meidiated IRF3 transcriptionally induced the production of CXCL16 in keratinocytes under virus invasion. In summary, our results demonstrate that MDA5 signaling orchestrates the aberrant skin immunity engaging in melanocyte death via mediating CXCL10 and CXCL16 secretion, which supports MDA5 as a potential therapeutic target for vitiligo under virus invasion.

Prediction of crucial epigenetically‑associated, differentially expressed genes by integrated bioinformatics analysis and the identification of S100A9 as a novel biomarker in psoriasis

Psoriasis is one of the most common immune-mediated inflammatory diseases of the skin. The identification of the pivotal molecular mechanisms responsible for the disease pathogenesis may lead to the development of novel therapeutic options. The present study aimed to identify pivotal differentially expressed genes (DEGs) and methylated DEGs in psoriasis. The raw data from gene microarrays were obtained from the Gene Expression Omnibus database. The data were processed using packages in Bioconductor. In total, 352 upregulated and 137 downregulated DEGs were identified. The upregulated DEGs were primarily enriched in the 'innate immune defense' response and the 'cell cycle'. The down-regulated DEGs were primarily enriched in 'cell adhesion' and 'tight junction pathways'. A total of 95 methylated DEGs were identified, which were significantly enriched in the 'interleukin (IL)-17 signaling pathway' and the 'response to interferon'. Based on a comprehensive evaluation of all algorithms in cytoHubba, the key epigenetic-associated hub genes (S100A9, SELL, FCGR3B, MMP9, S100A7, IL7R, IRF7, CCR7, IFI44, CXCL1 and LCN2) were screened out. In order to further validate these genes, the present study constructed a model of imiquimod (IMQ)-induced psoriasiform dermatitis using mice. The levels of these hub genes were increased in the IMQ group. The knockdown of methylation-regulating enzyme ten-eleven translocation (TET) 2 expression in mice attenuated the expression levels of S100A9, SELL, IL7R, MMP9, CXCL1 and LCN2. Furthermore, the hydroxymethylated level of S100A9 was highly expressed in the IMQ group and was significantly decreased by TET2 deficiency in mice. On the whole, using an integrative system bioinformatics approach, the present study identified a series of characteristic enrichment pathways and key genes that may serve as potential biomarkers in psoriasis.

Retinoids as an Immunity-modulator in Dermatology Disorders

The skin is the largest epithelial surface protecting the body from invading microbes. Vitamin A plays vital roles in the host defence of the skin, including promoting epithelial cell integrity, proliferation, and differentiation and even mediating immune responses. Furthermore, vitamin A derivatives, retinoid drugs, are widely used to treat skin diseases, such as acne and psoriasis. However, the immunoregulatory mechanisms of retinoids in dermatology have not been systematically described. In this paper, we discuss the immunological functions of retinoids during disease treatment, especially in skin disorders caused by exogenous infections.

Immunoregulatory Functions of the IL-12 Family of Cytokines in Antiviral Systems

Members of the interleukin 12 (IL-12) family have been known to be inflammatory factors since their discovery. The IL-12 family consists of IL-12, IL-23, IL-27, IL-35, and a new member, IL-39, which has recently been identified and has not yet been studied extensively. Current literature has described the mechanisms of immunity of these cytokines and potential uses for therapy and medical cures. IL-12 was found first and is effective in combatting a wide range of naturally occurring viral infections through the upregulation of various cytokines to clear the infected cells. IL-23 has an essential function in immune networks, can induce IL-17 production, and can antagonize inhibition from IL-12 in the presence of T helper (Th) 17 cells, resulting in type II IFN (IFN-γ) regulation. IL-27 has a competitive relationship to IL-35 because they both include the same subunit, the Epstein–Barr virus-induced gene3 (EBi3). This review provides a simple introduction to the IL-12 family and focuses on their functions relevant to their actions to counteract viral infections.

Severity, heterogeneity and systemic inflammation in psoriasis

Psoriasis may express as active severe disease or as mild stable disease. In particular, patients with active severe disease present systemic involvement, including comorbidities and increased values of parameters reflecting an active state of innate immunity. In contrast, patients with mild stable disease show a dominancy of acquired immunity. In this review article, we report the clinical aspects of disease manifestations of both active and quiescent psoriasis as well as the immunological aspects, as well as the impact on antimicrobial resistance. The activity of psoriasis is not captured in the present outcome measures for severity assessment. The present review suggests that incorporating disease activity may be important in the assessment of the efficacy of treatments.

The histone demethylase LSD1 promotes renal inflammation by mediating TLR4 signaling in hepatitis B virus-associated glomerulonephritis

Renal inflammation significantly contributes to the progression of hepatitis B virus (HBV)-associated glomerulonephritis (HBV-GN), but the mechanisms that control its precise regulation remain largely unknown. In this study, we showed that the lysine-specific demethylase 1 (LSD1) was significantly upregulated in renal tissue of HBV-GN patients, and its expression was positively correlated with inflammation. Functionally, LSD1 could promote HBV-induced release of proinflammatory mediators in HK-2 cells, a human renal tubular epithelial (RTE) cell line. Mechanistic investigations suggested that LSD1 directly promoted the transcription of the inflammatory-related gene Tlr4 by eliminating the mono- or di-methylation of H3K9 near its promoter. Knockdown of Lsd1 further inhibited TLR4-NF-κB/JNK signaling cascades, and subsequently decreased HBV-induced production of proinflammatory mediators in HK-2 cells. Co-transfection with Tlr4-expressing plasmids counteracted these effects. Meanwhile, downregulation of abovementioned TLR4-related pathways using small-molecule inhibitors attenuated inflammation. Importantly, LSD1 inhibitor tranylcypromine (TCP) could inhibit TLR4-NF-κB/JNK signaling axis and alleviate renal inflammation in HBV transgenic mice. Taken together, our data identify LSD1 as a novel regulator of renal inflammation and as a potential therapeutic target in HBV-GN.

Genistein suppresses psoriasis-related inflammation through a STAT3-NF-κB-dependent mechanism in keratinocytes

Psoriasis is a chronic recurrent skin inflammatory disease, and inhibition of inflammation may be an effective means of treating psoriasis. The flavonoid genistein has a clear anti-inflammatory effect. However, the anti-psoriatic effects of genistein and their underlying mechanisms remain unclear. In this study, we investigated the effects of genistein on imiquimod (IMQ)-induced psoriasis-like skin lesions in vivo and explored the mechanisms underlying those effects in vitro. It was found that genistein can significantly improve IMQ-induced pathological scores of cutaneous skin lesions in mice, reduce epidermal thickness, and inhibit the expression of inflammatory factors，including interleukin (IL)-1β, IL-6, tumour necrosis factor-alpha (TNF-α), chemokine ligand 2 (CCL2), IL-17 and IL-23. In vitro studies, genistein inhibited the proliferation of human keratinocyte HaCaT cells and inhibited the expression of inflammatory factors in a dose-dependent manner which induced by TNFα. Further researches showed that genistein could also significantly inhibit phosphorylated STAT3 (pSAT3) expression in IMQ mice dorsal skin and in TNF-α-induced HaCaT cells. The inhibitory effect of genistein on the expression of IL-6, IL-23 and TNF-α was weakened after Stat3 siRNA in HaCaT cells. Genistein could also significantly inhibit TNF-α induced the nuclear translocation of NF-κB, and inhibit the phosphorylation of I-kBα (pI-kBα). After combining with NF-κB blocker BAY 11-7082, the effect of genistein down-regulate the expression of TNF-α and VEGFA was attenuated in HaCaT cells. The results suggest that genistein may be developed for the treatment of psoriasis lesions.

Identification of a natural inhibitor of methionine adenosyltransferase 2A regulating one-carbon metabolism in keratinocytes

Background

Psoriasis is a common chronic inflammatory skin disease which lacks effective strategies for the treatment. Natural compounds with biological activities are good tools to identify new targets with therapeutic potentials. Acetyl-11-keto-β-boswellic acid (AKBA) is the most bioactive ingredient of boswellic acids, a group of compounds with anti-inflammatory and anti-cancer properties. Target identification of AKBA and metabolomics analysis of psoriasis helped to elucidate the molecular mechanism underlying its effect, and provide new target(s) to treat the disease.

Methods

To explore the targets and molecular mechanism of AKBA, we performed affinity purification, metabolomics analysis of HaCaT cells treated with AKBA, and epidermis of imiquimod (IMQ) induced mouse model of psoriasis and psoriasis patients.

Findings

AKBA directly interacts with methionine adenosyltransferase 2A (MAT2A), inhibited its enzyme activity, decreased level of S-adenosylmethionine (SAM) and SAM/SAH ratio, and reprogrammed one‑carbon metabolism in HaCaT cells. Untargeted metabolomics of epidermis showed one‑carbon metabolism was activated in psoriasis patients. Topical use of AKBA improved inflammatory phenotype of IMQ induced psoriasis-like mouse model. Molecular docking and site-directed mutagenesis revealed AKBA bound to an allosteric site at the interface of MAT2A dimer.

Interpretation

Our study extends the molecular mechanism of AKBA by revealing a new interacting protein MAT2A. And this leads us to find out the dysregulated one‑carbon metabolism in psoriasis, which indicates the therapeutic potential of AKBA in psoriasis.

Fund

The National Natural Science Foundation, the National Program on Key Basic Research Project, the Shanghai Municipal Commission, the Leading Academic Discipline Project of the Shanghai Municipal Education Commission.

The epithelial immune microenvironment (EIME) in atopic dermatitis and psoriasis

The skin provides both a physical barrier and an immunologic barrier to external threats. The protective machinery of the skin has evolved to provide situation-specific responses to eliminate pathogens and to provide protection against physical dangers. Dysregulation of this machinery can give rise to the initiation and propagation of inflammatory loops in the epithelial microenvironment that result in inflammatory skin diseases in susceptible people. A defective barrier and microbial dysbiosis drive an interleukin 4 (IL-4) loop that underlies atopic dermatitis, while in psoriasis, disordered keratinocyte signaling and predisposition to type 17 responses drive a pathogenic IL-17 loop. Here we discuss the pathogenesis of atopic dermatitis and psoriasis in terms of the epithelial immune microenvironment-the microbiota, keratinocytes and sensory nerves-and the resulting inflammatory loops.

Differentially expressed non-coding RNAs induced by transmissible gastroenteritis virus potentially regulate inflammation and NF-κB pathway in porcine intestinal epithelial cell line

Background

Transmissible gastroenteritis virus (TGEV) infection can activate NF-κB pathway in porcine intestinal epithelial cells and result in severe inflammation. Non-coding RNAs (ncRNAs) are not translated into proteins and play an important role in many biological and pathological processes such as inflammation, viral infection, and mitochondrial damage. However, whether ncRNAs participate in TGEV-induced inflammation in porcine intestinal epithelial cells is largely unknown.

Results

In this study, the next-generation sequencing (NGS) technology was used to analyze the profiles of mRNAs, miRNAs, and circRNAs in Mock- and TGEV-infected intestinal porcine epithelial cell-jejunum 2 (IPEC-J2) cell line. A total of 523 mRNAs, 65 microRNAs (miRNAs), and 123 circular RNAs (circRNAs) were differentially expressed. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed differentially expressed mRNAs were linked to inflammation-related pathways, including NF-κB, Toll-like receptor, NOD-like receptor, Jak-STAT, TNF, and RIG-I-like receptor pathways. The interactions among mRNA, miRNA, and circRNA were analyzed. The data showed that ssc_circ_009380 and miR-22 might have interaction relationship. Dual-luciferase reporter assay confirmed that miR-22 directly bound to ssc_circ_009380. We also observed that overexpression of miR-22 led to a reduction of p-IκB-α and accumulation of p65 in nucleus in TGEV-infected IPEC-J2 cells. In contrast, inhibition of miR-22 had the opposite effects. Moreover, silencing of ssc_circ_009380 inhibited accumulation of p65 in nucleus and phosphorylation of IκB-α.

Conclusions

The data revealed that differentially expressed mRNAs and ncRNAs were primarily enriched in inflammation-related pathways and ssc_circ_009380 promoted activation of NF-κB pathway by binding miR-22 during TGEV-induced inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5128-5) contains supplementary material, which is available to authorized users.

MicroRNA-210 overexpression promotes psoriasis-like inflammation by inducing Th1 and Th17 cell differentiation

Immune imbalance of T lymphocyte subsets is a hallmark of psoriasis, but the molecular mechanisms underlying this aspect of psoriasis pathology are poorly understood. Here, we report that microRNA-210 (miR-210), a miR that is highly expressed in both psoriasis patients and mouse models, induces helper T (Th) 17 and Th1 cell differentiation but inhibits Th2 differentiation through repressing STAT6 and LYN expression, contributing to several aspects of the immune imbalance in psoriasis. Both miR-210 ablation in mice and inhibition of miR-210 by intradermal injection of antagomir-210 blocked the immune imbalance and the development of psoriasis-like inflammation in an imiquimod-induced or IL-23-induced psoriasis-like mouse model. We further showed that TGF-β and IL-23 enhance miR-210 expression by inducing HIF-1α, which recruits P300 and promotes histone H3 acetylation in the miR-210 promoter region. Our results reveal a crucial role for miR-210 in the immune imbalance of T lymphocyte subsets in psoriasis and suggest a potential therapeutic avenue.

p38α signaling in Langerhans cells promotes the development of IL-17-producing T cells and psoriasiform skin inflammation

Dendritic cells (DCs) contribute to psoriasis pathogenesis. In a mouse model of imiquimod-induced psoriasiform skin inflammation, we found that p38α activity in Langerhans cells (LCs), a skin-resident subset of DCs, promoted the generation of T cells that produce IL-17, a proinflammatory cytokine that is implicated in autoimmune disease. Deletion of p38α in LCs, but not in other skin or circulating DC subsets or T cells, decreased T cell-mediated psoriasiform skin inflammation in mice. The activity of p38α in LCs specifically promoted IL-17 production from γδ and CD4⁺ T cells by increasing the abundance of IL-23 and IL-6, two cytokines that stimulate IL-17 secretion. Inhibition of p38 activity through either pharmacological inhibition or genetic deletion also reduced the severity of established psoriasiform skin inflammation. Together, our findings indicate a critical role for p38α signaling in LCs in promoting inflammatory responses in the skin and suggest that targeting p38α signaling in LCs may offer an effective therapeutic approach to treat psoriasis.

Innate Antiviral Immunity in the Skin

Barrier sites such as the skin play a critical role in immune defense. They must maintain homeostasis with commensals and rapidly detect and limit pathogen invasion. This is accomplished in part through the production of endogenous antimicrobial peptides and proteins, which can be either constitutive or inducible. Here, we focus particularly on the control of innate antiviral proteins and present the basic aspects of their regulation in the skin by interferons (IFNs), IFN-independent immunity, and environmental factors. We also discuss the activity and (dys-)function of antiviral proteins in the context of skin-tropic viruses and highlight the relevance of the innate antiviral pathway as a potential therapeutic avenue for vulnerable patient populations and skin diseases with high risk for virus infections.