Inhibition of CtBP-Regulated Proinflammatory Gene Transcription Attenuates Psoriatic Skin Inflammation.

Psoriasis is a chronic immune-mediated disease characterized by excessive proliferation of epidermal keratinocytes and increased immune cell infiltration to the skin. Although it is well-known that psoriasis pathogenesis is driven by aberrant production of proinflammatory cytokines, the mechanisms underlying the imbalance between proinflammatory and anti-inflammatory cytokine expression are incompletely understood. In this study, we report that the transcriptional coregulators CtBP1 and 2 can transactivate a common set of proinflammatory genes both in the skin of imiquimod-induced mouse psoriasis model and in human keratinocytes and macrophages stimulated by imiquimod. We find that mice overexpressing CtBP1 in epidermal keratinocytes display severe skin inflammation phenotypes with increased expression of T helper type 1 and T helper type 17 cytokines. We also find that the expression of CtBPs and CtBP-target genes is elevated both in human psoriatic lesions and in the mouse imiquimod psoriasis model. Moreover, we were able to show that topical treatment with a peptidic inhibitor of CtBP effectively suppresses the CtBP-regulated proinflammatory gene expression and thus attenuates psoriatic inflammation in the imiquimod mouse model. Together, our findings suggest to our knowledge previously unreported strategies for therapeutic modulation of the immune response in inflammatory skin diseases.

Cancer cell membrane-coated nanoparticles for bimodal imaging-guided photothermal therapy and docetaxel-enhanced immunotherapy against cancer.

BACKGROUND: Mono-therapeutic modality has limitations in combating metastatic lesions with complications. Although emerging immunotherapy exhibits preliminary success, solid tumors are usually immunosuppressive, leading to ineffective antitumor immune responses and immunotherapeutic resistance. The rational combination of several therapeutic modalities may potentially become a new therapeutic strategy to effectively combat cancer. RESULTS: Poly lactic-co-glycolic acid (PLGA, 50 mg) nanospheres were constructed with photothermal transduction agents (PTAs)-Prussian blue (PB, 2.98 mg) encapsulated in the core and chemotherapeutic docetaxel (DTX, 4.18 mg)/ immune adjuvant-imiquimod (R837, 1.57 mg) loaded in the shell. Tumor cell membranes were further coated outside PLGA nanospheres (designated "M@P-PDR"), which acted as "Nano-targeted cells" to actively accumulate in tumor sites, and were guided/monitored by photoacoustic (PA)/ magnetic resonance (MR) imaging. Upon laser irradiation, photothermal effects were triggered. Combined with DTX, PTT induced in situ tumor eradication. Assisted by the immune adjuvant R837, the maturation rate of DCs increased by 4.34-fold compared with that of the control. In addition, DTX polarized M2-phenotype tumor-associated macrophages (TAMs) to M1-phenotype, relieving the immunosuppressive TME. The proportion of M2-TAMs decreased from 68.57% to 32.80%, and the proportion of M1-TAMs increased from 37.02% to 70.81%. Integrating the above processes, the infiltration of cytotoxic T lymphocytes (CTLs) increased from 17.33% (control) to 35.5%. Primary tumors and metastasis were significantly inhibited when treated with "Nano-targeted cells"-based cocktail therapy. CONCLUSION: "Nano-targeted cells"-based therapeutic cocktail therapy is a promising approach to promote tumor regression and counter metastasis/recurrence.

Curcumin alleviates imiquimod-induced psoriasis in progranulin-knockout mice.

Recent advances have revealed that progranulin (PGRN) is related to the aetiology of psoriasis. Moreover, curcumin, a compound derived from turmeric, has been proposed as a potential therapeutic approach in psoriasis-like dermatitis, but it is still unclear whether curcumin affects the development of psoriasis-like skin lesions under PGRN-deficient conditions. Therefore, in this study, we developed a mouse model of psoriatic skin lesions using topical application of imiquimod (IMQ) in both wild type and PGRN-knockout mice to test this possibility. We observed that PGRN deficiency not only increased proinflammatory cytokine IL-17A levels and aggravated psoriasis-like damaged appearance and epidermal thickening but also directly mediated changes in keratinocyte proliferation (Krt 14, cyclinD1 and c-Myc) and differentiation (Krt 10 and Filaggrin) associated gene expression following IMQ challenge, compared to those in the control group. Furthermore, curcumin treatment (50 mg/kg and 200 mg/kg, intragastrically) for 21 consecutive days suppressed the IMQ exposure-induced increase in PGRN expression. Importantly, curcumin treatment significantly alleviated the PGRN deficiency-induced exacerbation of psoriatic appearance, histological features and keratinocyte proliferation after IMQ exposure. In summary, these results demonstrate the direct regulation of PGRN in keratinocyte proliferation and differentiation in psoriatic lesions and demonstrate the protective effect of curcumin on PGRN deficiency-induced psoriatic skin lesion exacerbation.

Protectin D1 reduces imiquimod-induced psoriasiform skin inflammation.

Specialized proresolving mediators are enzymatically oxygenated natural molecules derived from polyunsaturated fatty acids and are considered novel. These novel mediators include lipoxins from arachidonic acid, resolvins and protectins from omega-3 essential fatty acids, and new maresins. These mediators harbor potent dual proresolving and anti-inflammatory properties. Resolvins and protectins are known to be potent when administered to various inflammation-associated animal models of human diseases. Although psoriasis' etiology remains unknown, there is accumulating evidence indicating that cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-23, and IL-17, play pivotal roles in its development. Experimentally, resolvins, maresins, and lipoxins downregulate the cytokine expression of the IL-23/IL-17 axis and inhibition of mitogen-activated protein kinases and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) cell signaling transduction pathways. Here, we assessed the effects of protectin D1 (PD1) on imiquimod (IMQ)-induced psoriasiform skin inflammation and keratinocytes. PD1 showed clinical improvement in skin thickness, redness, and scaling in psoriasis mouse models. Moreover, PD1 decreased IL-1ß, IL-6, IL-17, and CXCL1 mRNA expressions and reduced STAT1 and NF-κB signaling pathway activation in lesions. Serum myeloperoxidase, IgG2a, IL-1ß, IL-6, IL-17, and TNF-α and spleen CD4+IFN-γ+IL-17+ T lymphocytes were reduced after PD1 treatment in IMQ-induced psoriasiform mouse models. In addition, IL-1ß, IL-6, IL-8, and IL-18BP gene expressions were decreased in PD1-treated keratinocytes. Moreover, a decrease in the expression levels of CCL17 and IL-6 and an inhibition of the STAT1 and NF-κB signaling transduction pathways was observed in keratinocytes. These PD1 anti-inflammatory effects suggest that it is a good therapeutic candidate for psoriasis.

Immunogenicity in humans of a transdermal multipeptide melanoma vaccine administered with or without a TLR7 agonist.

BACKGROUND: Experimental cancer vaccines are traditionally administered by injection in subcutaneous tissue or muscle, commonly with adjuvants that create chronic inflammatory depots. Injection of melanoma-derived peptides induces T cell responses; however, the depots that form following injection may inhibit optimization of the immune response. In skin, epidermal Langerhans cells (LC) are a dominant source of professional antigen presenting cells. We hypothesized that: (1) applying melanoma-derived peptides topically, in proximity to LC, could be immunogenic and safe, with low vaccine-site toxicity and (2) topical toll-like receptor 7 (TLR7) agonist would increase immunogenicity of the peptide vaccine. METHODS: Twelve melanoma peptides plus a tetanus helper peptide were combined with granulocyte macrophage colony stimulating factor (GM-CSF) and were administered topically on days 1, 8, and 15, to 28 patients randomized to one of four adjuvant preparations: (1) incomplete Freund's adjuvant (IFA); (2) IFA plus a TLR7 agonist (imiquimod) administered on days 0, 7, 14; (3) dimethyl sulfoxide (DMSO) or (4) DMSO+ imiquimod administered on day 0, 7, 14. Every 3 weeks thereafter (x 6), the peptides were combined with GM-CSF and were injected into the dermis and subcutis in an emulsion with IFA. Toxicities were recorded and immune responses assayed by ELIspot. RESULTS: CD8+ T cell responses to transdermal vaccination in DMSO occurred in 83% of participants in group 3 and 86% in group 4, and responses to vaccination in IFA were observed in 29% of participants in group 1 and 14% in group 2. Overall, 61% of participants had CD4+ T cell immune responses to the tetanus peptide, with large, durable responses in groups 3 and 4. Five of seven participants in group 4 had a severe rash, one that was dose limiting. Ten-year overall survival was 67% and disease-free survival was 44%. CONCLUSIONS: These data provide proof of principle for immunogenicity in humans of transdermal immunization using peptides in DMSO. Further study is warranted into the pharmacokinetics and immunobiology of TLR agonists as vaccine adjuvants during transcutaneous application. Overall survival is high, supporting further investigation of this immunization approach.

Fingolimod ameliorates imiquimod-induced psoriasiform dermatitis by sequestrating interleukin-17-producing ?d T cells in secondary lymph nodes.

BACKGROUND: Psoriasis is a chronic inflammatory skin disease. Interleukin (IL)-17A plays a key role in the pathogenesis of psoriasis. Fingolimod, which is available for the treatment of multiple sclerosis, exerts anti-inflammatory effects by sequestrating inflammatory lymphocytes in secondary lymphoid tissues and the thymus. The effect of fingolimod on psoriasis has not been reported yet. OBJECTIVE: Our objectives were to investigate the effect of fingolimod on psoriasis utilizing mice with imiquimod (IMQ)-induced psoriasiform dermatitis, and explore the possibility of fingolimod as a therapeutic agent for psoriasis. METHODS: Psoriasiform dermatitis was induced by imiquimod application on murine shaved back skin for six days. Fingolimod prepared in phosphate-buffered saline (PBS), or PBS alone as a control, was administered intraperitoneally daily from days 0 to 5. RESULTS: Fingolimod ameliorated IMQ-induced psoriasis dermatitis clinically and histologically. On day 6, the mRNA expression level of IL-17A was lower in the skin of fingolimod-treated mice than in that of PBS-treated mice, whereas it was higher in the inguinal lymph nodes of fingolimod-treated mice than in those of PBS-treated mice. Flow cytometric analyses revealed that fingolimod reduced IL-17A-producing ?d T cells infiltrating into the skin, whereas it increased these cells in the inguinal lymph nodes. Fingolimod inhibited egress of Langerhans cells from the skin to lymph nodes. CONCLUSION: Our results demonstrated that fingolimod showed effectiveness for IMQ-induced psoriasiform dermatitis by hindering the emigration of IL-17A-producing ?d T cells from the lymph nodes to the skin, and suggest that fingolimod is a promising candidate for the treatment of psoriasis.

The nerve injuries attenuate the persistence of psoriatic lesions.

BACKGROUND: The involvement of the nerve in psoriasis development was suggested by sporadic case reports. OBJECTIVES: To provide multiple evidence for the nerve in psoriasis development with a retrospective case review, a literature review and a mouse-based experimental experiment. METHODS: Psoriatic patients who had concomitant nerve injuries and such cases from literatures were reviewed. And, on wild-type mouse level, unilateral denervation surgery was performed on the dorsal skin before and after the induction of psoriasiform dermatitis, respectively. Lesion visual scores were calculated, and biopsies were taken for hematoxylin-eosin (HE) staining, immunofluorescence analysis, and RNA sequencing & bioinformatics analysis before denervation surgery and the 2nd, 4th, 6th, 8th day after the surgery. RESULTS: All clinical cases (20/20) showed that local lesions under the control of injured nerves relieved spontaneously or even cleared/spared, and only about 1/3 experienced partial recurrence. Next, mouse psoriasiform experiments demonstrated that unilateral denervation prior to imiquimod application attenuated the enhancement of inflammatory reactions (e.g. adaptive immune response and Th17 cell differentiation pathway) and the induction of ipsilateral psoriasiform dermatitis. On the other hand, unilateral denervation after psoriasiform dermatitis induction promoted the regression of inflammatory reactions (e.g. T cell activation, TNF signaling, and Th17 cell differentiation pathway) and ipsilateral dermatitis recovery. CONCLUSION: Our study based on both retrospective clinical case review and wild-type mouse experiments provides multiple evidence for the involvement of the nerve in psoriasis development. Regulation of immune events, including TNF signaling and Th17 cell differentiation, may be the mechanisms of the nerve in psoriasis.

CCR4 Involvement in the Expansion of T Helper Type 17 Cells in a Mouse Model of Psoriasis.

Psoriasis is a chronic skin disease associated with T helper (Th)17-mediated inflammation. Because CCR4 is a major chemokine receptor expressed on Th17 cells, we investigated the role of CCR4 in a modified imiquimod-induced psoriasis model that showed enhanced skin infiltration of Th17 cells. CCR4-deficient mice had less severe skin disease than wild-type mice. Th17 cells were decreased in the skin lesions and regional lymph nodes of CCR4-deficient mice. In the regional lymph nodes of wild-type mice, CD44+ memory Th17 cells expressing CCR4 were found to be clustered with dendritic cells expressing CCL22, a ligand for CCR4. Such dendritic cell‒Th17 cell clusters were significantly decreased in CCR4-deficient mice. Similar results were obtained using the IL-23‒induced psoriasis model. In vitro, compound 22, a CCR4 antagonist, significantly reduced the expansion of Th17 cells in the coculture of CD11c+ dendritic cells and CD4+ T cells separately prepared from the regional lymph nodes of wild-type mice with psoriasis. In vivo, compound 22 ameliorated the psoriasis-like skin disease in wild-type mice with significant decreases of Th17 cells in the regional lymph nodes and skin lesions. Collectively, CCR4 is likely to play a role in the pathogenesis of psoriasis through the expansion of Th17 cells.

Skin-Homing Regulatory B Cells Required for Suppression of Cutaneous Inflammation.

Pro and anti-inflammatory B-cell subsets that localize to unperturbed and inflamed skin are newly emerging components of the skin immune system. To test the relevance of regulatory B cells (Bregs) in the suppression of cutaneous inflammation, we asked whether impaired migration of these cells into the skin exacerbates skin inflammation. Using a mouse model with a B-cell‒specific tamoxifen-inducible deletion of α4ß1 integrin, we demonstrate that selective disruption of α4ß1-integrin expression in B cells significantly decreases IL-10+ Bregs in inflamed skin, whereas it does not affect their counterparts in lymphoid tissues. Impaired skin homing and reduced cutaneous accumulation of IL-10+ Bregs lead to a significant increase in clinical and histopathological parameters of inflammation in both psoriasiform skin inflammation and cutaneous delayed contact hypersensitivity. Thus, our data show a crucial function of skin-homing IL-10+ Bregs in the suppression of skin inflammation, supporting the notion that Bregs are critical players in the cutaneous environment during inflammatory skin diseases.

Short-Term Western Diet Intake Promotes IL-23‒Mediated Skin and Joint Inflammation Accompanied by Changes to the Gut Microbiota in Mice.

We previously showed that exposure to a high-sugar and moderate-fat diet (i.e., Western diet [WD]) in mice induces appreciable skin inflammation and enhances the susceptibility to imiquimod-induced psoriasiform dermatitis, suggesting that dietary components may render the skin susceptible to psoriatic inflammation. In this study, utilizing an IL-23 minicircle-based model with features of both psoriasiform dermatitis and psoriatic arthritis, we showed that intake of WD for 10 weeks predisposed mice not only to skin but also to joint inflammation. Both WD-induced skin and joint injuries were associated with an expansion of IL-17A‒producing γδ T cells and increased expression of T helper type 17 cytokines. After IL-23 minicircle delivery, WD-fed mice had reduced microbial diversity and pronounced dysbiosis. Treatment with broad-spectrum antibiotics suppressed IL-23‒mediated skin and joint inflammation in the WD-fed mice. Strikingly, reduced skin and joint inflammation with a partial reversion of the gut microbiota were noted when mice switched from a WD to a standard diet after IL-23 minicircle delivery. These findings reveal that a short-term WD intake‒induced dysbiosis is accompanied by enhanced psoriasis-like skin and joint inflammation. Modifications toward a healthier dietary pattern should be considered in patients with psoriatic skin and/or joint disease.

Inhibiting Protein Kinase Activity of Pyruvate Kinase M2 by SIRT2 Deacetylase Attenuates Psoriasis.

Signal transducer and activator of transcription 3 (STAT3) is crucial for the pathogenesis of psoriasis. Studies describe pleiotropic roles for a glycolytic enzyme pyruvate kinase M2 (PKM2) as a nuclear kinase of STAT3. However, little is known about the function of PKM2 in T helper type 17 cells in association with STAT3. In this study, we investigated whether and how SIRT2 deacetylase regulated the protein kinase function of PKM2 in T helper type 17 cell‒mediated inflammatory responses in psoriasis. Sirt2 knockout mice and wild-type littermates had psoriatic dermatitis induced by topical treatment of imiquimod or intradermal injection of recombinant IL-23. An initial downregulation of SIRT2 and an increase in PKM2 acetylation and STAT3 phosphorylation were observed in psoriasiform lesions of mice. SIRT2 directly interacted with and deacetylated PKM2 to suppress STAT3 phosphorylation. Consequently, psoriasiform skin inflammation was aggravated in Sirt2 knockout mice. Conversely, genetic re-expression of Sirt2 or pharmacological blockade of PKM2 decreased the disease severity. Flow cytometric analysis of skin tissues of Sirt2 knockout mice showed enhanced infiltration of T helper type 17 cells. Ex vivo experiments showed that SIRT2 deficiency accelerated T helper type 17 cell differentiation with the concomitant production of IL-17A and IL-22. The results suggest SIRT2-mediated PKM2 deacetylation as an effective option for psoriasis therapy.

An Autocrine Circuit of IL-33 in Keratinocytes Is Involved in the Progression of Psoriasis.

IL-33 is constitutively expressed in the skin. Psoriasis is a common skin inflammatory disease. The roles of IL-33 in psoriasis have not been well-elucidated. We identified that keratinocytes (KCs) are the predominant cells expressing IL-33 and its receptor, suppression of tumorigenicity 2, in the skin. KCs actively released IL-33 on psoriasis inflammatory stimuli and induced psoriasis-related cytokine, chemokine, and inflammatory molecules genes transcription in KCs in an autocrine manner. IL-33‒specific deficiency in KCs ameliorated imiquimod-induced psoriatic dermatitis. In addition, intradermal injection of recombinant IL-33 alone induced psoriasis-like dermatitis, which is attributed to the transcriptional upregulation of genes enriched in IL-17, TNF, and chemokine signaling pathway in KCs on recombinant IL-33 stimulation. Our data demonstrate that the autocrine circuit of IL-33 in KCs promotes the progression of psoriatic skin inflammation, and IL-33 is a potential therapeutic target for psoriasis.

OVOL1 Regulates Psoriasis-Like Skin Inflammation and Epidermal Hyperplasia.

Psoriasis is a common inflammatory skin disease characterized by aberrant inflammation and epidermal hyperplasia. Molecular mechanisms that regulate psoriasis-like skin inflammation remain to be fully understood. Here, we show that the expression of Ovol1 (encoding ovo-like 1 transcription factor) is upregulated in psoriatic skin, and its deletion results in aggravated psoriasis-like skin symptoms following stimulation with imiquimod. Using bulk and single-cell RNA sequencing, we identify molecular changes in the epidermal, fibroblast, and immune cells of Ovol1-deficient skin that reflect an altered course of epidermal differentiation and enhanced inflammatory responses. Furthermore, we provide evidence for excessive full-length IL-1α signaling in the microenvironment of imiquimod-treated Ovol1-deficient skin that functionally contributes to immune cell infiltration and epidermal hyperplasia. Collectively, our study uncovers a protective role for OVOL1 in curtailing psoriasis-like inflammation and the associated skin pathology.

Neutrophils Enhance Cutaneous Vascular Dilation and Permeability to Aggravate Psoriasis by Releasing Matrix Metallopeptidase 9.

Neutrophil infiltration and papillary vessel dilation are hallmarks of the initiation phase of psoriatic lesions. However, how neutrophils aggravate psoriasis development during transendothelial migration and the interaction between neutrophils and cutaneous vascular endothelial cells are less well-understood. In this study, we reported that neutrophils and cutaneous vascular endothelial cells activated each other when neutrophils migrated through the cutaneous endothelial barrier. In addition, neutrophil infiltration into skin lesions caused vascular remodeling including cutaneous vasodilation and enhanced vascular permeability in vivo and in vitro. Microarray gene profile data showed that matrix metallopeptidase (MMP)-9 was overexpressed in psoriatic neutrophils, and zymography assay further validated the bioactivity of MMP-9 secreted by psoriatic neutrophils. Moreover, MMP-9 activated vascular endothelial cells through the extracellular signal‒regulated kinase 1/2 and p38-MAPK signaling pathways, enhancing CD4+ T-cell transmigration in vitro. Correspondingly, an MMP-9 inhibitor significantly reduced cutaneous vasodilation, vascular permeability, and psoriatic symptoms in an imiquimod- or IL-23‒induced psoriasiform mouse model. Overall, our study demonstrates that neutrophil-derived MMP-9 induces cutaneous vasodilation and hyperpermeability by activating cutaneous vascular endothelial cells, thus facilitating psoriatic lesion development, which increases our knowledge on the role of neutrophils in the pathogenesis of psoriasis.

Suppression of neuropeptide by botulinum toxin improves imiquimod-induced psoriasis-like dermatitis via the regulation of neuroimmune system.

BACKGROUND: Psoriasis is a multifactorial disease arises from a complex interaction of genetics, immune system, and environmental aspects. IL-23/Th17 immune axis has been considered as a primary modulator in psoriasis. In addition, several findings imply that nervous system may take a part in the pathogenesis of psoriasis, suggesting that nervous system, through its neuropeptide, may interact with immune system and lead to the formation of psoriasis. OBJECTIVE: We aimed to ascertain the role of neuropeptides secreted from neurons in the pathogenesis of psoriasis in vivo. METHODS: The release of neuropeptide was inhibited by injecting Botulinum toxin B (BTX-B) on Imiquimod (IMQ)-induced psoriasis-like dermatitis mice model. Quantification of skin dermatitis, infiltrating inflammatory cells, and the production of cytokines at the lesional skin area were performed by PSI score, immunostaining, and real-time PCR. We also tested the effect of selective CGRP antagonist (CGRP8-37) on psoriasis-like dermatitis in IMQ-treated mice. RESULTS: BTX-B injection significantly suppressed PSI score and reduced the number of CD4+ T cells, CD11c+ dendritic cells, and the production of IL-17A/F in the lesional skin. The expressions of PGP9.5+ nerve fibers and neuropeptides (SP, CGRP) were also significantly reduced following BTX-B injection. Additionally, CGRP antagonist also suppressed the development of IMQ-induced psoriasis-like dermatitis in mice. CONCLUSION: The suppression of neuropeptide secretion in the skin by BTX injection might inhibit nerve elongation, the infiltration of immune cells, as well as IL-17 production, resulting in the improvement of psoriasis. Neuropeptide inhibitor could also be applied to the treatment of psoriasis.

Imiquimod-induced dermatitis impairs thymic tolerance of autoreactive CD4+ T cells to desmoglein 3.

BACKGROUND: The thymus plays an essential role in removing autoreactive T cells. Autoantigen-expressing thymic epithelial cells (TECs) contribute to the tolerogenic process. The thymus transiently shrinks as an acute thymic involution (ATI) under various inflammatory conditions. However, whether ATI occurs during local skin inflammation remains unclear, as does its influence on thymic immune tolerance. OBJECTIVE: We investigated whether imiquimod-induced dermatitis causes ATI and impairs thymic immune tolerance against desmoglein 3 (Dsg3), an epidermal autoantigen of pemphigus vulgaris. METHODS: 5% imiquimod cream was applied daily, at 62.5 mg/day (high dose group) or 31.25 mg/day (low dose group), for 1 week on the back of wild-type mice, and to wild-type mice that had undergone bone-marrow transplantation from Dsg3-specific T-cell receptor (TCR) transgenic-Rag2-/- mice. Next, thymocytes, TECs and other immune cells were analyzed by flow cytometry. TEC-associated Dsg3 expression was also analyzed by immunofluorescence staining. RESULTS: Thymus weight and thymocyte number in all developmental stages decreased in a dose-dependent manner under imiquimod-induced dermatitis. The number of total TECs, specifically medullary, but not cortical, TECs, decreased in high and low dose groups. Accordingly, the number of Dsg3-experssing UEA-1+keratin 5+mTEC decreased in the thymus during imiquimod-induced dermatitis. Although Dsg3-sepcific transgenic thymocytes was usually deleted in the thymus under physiological condition by central tolerance, Dsg3-sepcific transgenic CD4+CD8- thymocytes significantly increased in number under imiquimod-induced dermatitis. CONCLUSION: These findings indicate a crosstalk between skin and thymus in adult mice and suggest that skin inflammation may impair thymic tolerance to autoantigens, such as Dsg3.

Dihydroartemisinin ameliorates psoriatic skin inflammation and its relapse by diminishing CD8+ T-cell memory in wild-type and humanized mice.

Conventional immunosuppressants cause side effects and do not prevent the recurrence of autoimmune diseases. Moreover, they may not inhibit autoimmunity mediated by pathogenic memory T-cells. Dihydroartemisinin (DHA) has been shown to regulate autoimmunity. However, it remains unknown whether DHA impacts psoriasis and its recurrence. The objective of this study was to determine therapeutic effects of DHA on psoriasis and its relapse as well as its underlying mechanisms. Methods: We established animal models of imiquimod (IMQ)-induced psoriasis-like wild-type mice and humanized NSG mice receiving lesional human skin from patients with psoriasis. Many immunoassays, including immunohistochemistry, flow cytometry, quantitative RT-PCR and Western blotting, were performed. Results: We found that DHA not only ameliorated acute skin lesion of psoriatic mice, but also alleviated its recurrence by diminishing CD8+ central memory T (TCM) and CD8+ resident memory T (TRM) cells. It attenuated epidermal pathology and T-cell infiltration in the skin of IMQ-induced psoriatic mice while suppressing expression of IL-15, IL-17 and other proinflammatory cytokines in the skin. Surprisingly, DHA reduced the frequency and number of CD8+, but not CD4+, subset of CD44highCD62Lhigh TCM in psoriatic mice, whereas methotrexate (MTX) lowered CD4+, but not CD8+, TCM frequency and number. Indeed, DHA, but not MTX, downregulated eomesodermin (EOMES) and BCL-6 expression in CD8+ T-cells. Furthermore, DHA, but not MTX, reduced the presence of CD8+CLA+, CD8+CD69+ or CD8+CD103+ TRM cells in mouse skin. Interestingly, treatment with DHA, but not MTX, during the first onset of psoriasis largely prevented psoriasis relapse induced by low doses of IMQ two weeks later. Administration of recombinant IL-15 or CD8+, but not CD4+, TCM cells resulted in complete recurrence of psoriasis in mice previously treated with DHA. Finally, we demonstrated that DHA alleviated psoriatic human skin lesions in humanized NSG mice grafted with lesional skin from psoriatic patients while reducing human CD8+ TCM and CD103+ TRM cells in humanized mice. Conclusion: We have provided the first evidence that DHA is advantageous over MTX in preventing psoriasis relapse by reducing memory CD8+ T-cells.

Single-cell RNA-Seq reveals the transcriptional landscape and heterogeneity of skin macrophages in Vsir-/- murine psoriasis.

Rationale: V-domain immunoglobulin suppressor of T cell activation (VISTA) is a novel inhibitory immune checkpoint molecule. Vsir-/- mice have exacerbated psoriasis-like skin inflammation. The immune cell subsets involved in inflammation in Vsir-/- psoriatic mice are largely unknown. We have used scRNA-seq as an unbiased profiling strategy to study the heterogeneity of immune cells at a single cell level in the skin of Vsir-/- psoriatic mice. Methods: In the present study, the right ear and shaved back skin of wild type and Vsir-/- mice were treated with IMQ for 5 consecutive days to induce psoriasis-like dermatitis. Then, the single-cell RNA sequencing analysis of mouse back skin lesions was performed using 10 × Genomics technique. Results: We identified 12 major cell subtypes among 23,258 cells. The major populations of the skin cells included macrophages, dendritic cells and fibroblasts. Macrophages constituted the main immune cell population in the WT (61.29%) and Vsir-/- groups (77.7%). It should be noted that DCs and fibroblasts were expanded in the Vsir-/- psoriatic mice. Furthermore, the gene expression signatures were assessed. We observed that Hspb1 and Cebpb were significantly upregulated in the Vsir-/- psoriatic mice. Differential gene expression and gene ontology enrichment analyses revealed specific gene expression patterns distinguishing these subsets and uncovered putative functions of each cell type. Date analysis resulted in the discovery of a number of novel psoriasis-associated genes in Vsir-/- mice. Conclusion: We present a comprehensive single-cell landscape of the skin immune cells in Vsir-/- psoriatic mice. These unprecedented data uncovered the transcriptional landscape and phenotypic heterogeneity of skin macrophages in psoriasis and identified their gene expression signature suggesting specialized functions in Vsir-/- mice. Our findings will open novel opportunities to investigate the role of VISTA in driving psoriasis.

A monocyte-keratinocyte-derived co-culture assay accurately identifies efficacies of BET inhibitors as therapeutic candidates for psoriasiform dermatitis.

BACKGROUND: Bromodomain and extra-terminal (BET) proteins perform key roles in epigenetic control of gene expression that is involved in inflammatory conditions, including psoriasiform dermatitis (PsD). Predicting which (of many potential available BET inhibitors) will be effective in vivo is challenging. OBJECTIVE: We determine if a novel in vitro assay that includes two critical cell types involved in human psoriasis can predict the therapeutic potential of specific BET inhibitors in vivo. METHODS: An in vitro model consisting of U-937 and HaCaT cell co-culture was created to screen small molecule BET antagonists for inhibition of cutaneous inflammatory genes. Efficacious BET inhibitors were tested in a mouse imiquimod (IMQ)-induced PsD model. RESULTS: In the co-culture system, HaCaT cells exhibited a marked increase in the secretion of a characteristic set of proinflammatory and Th17-associated cytokines. Of the ten commercially-available small molecules targeting BET proteins assayed, most compounds exhibited inhibitory functions at 1 µM against inflammatory activation, but responded variably at lower concentrations. OTX015, a typical representative for most of the compounds, barely inhibited the inflammatory reactions at 0.1 µM. By contrast, ABBV075 was effective in concentrations as low as 0.01 µM. While oral administration OTX015 in IMQ-treated mice reduced disease severity, ABBV075 equally decreased the symptoms and molecular and cellular severity markers at one-tenth of the minimal dosing required for OTX015. CONCLUSION: In vitro screening system combined with an in vivo animal model, can serve as a convenient pre-clinical screening tool for the selection of BET inhibitors (and possibly other drugs) that may have clinical potential in psoriasis therapy.