Chronic Psoriatic Skin Inflammation Leads to Increased Monocyte Adhesion and Aggregation

Single-cell RNA sequencing highlights the influence of innate and adaptive immune response mechanisms in psoriatic arthritis

Introduction

Psoriatic arthritis (PsA) is a chronic immune-mediated inflammatory disease displaying heterogeneous symptoms. However, the association between the clinical heterogeneity of PsA and disease immunopathogenesis remains poorly understood complicating diagnostic precision. A knowledge gap remains on whether it is possible to distinguish the clinical PsA phenotypes on the immune cellular level. The primary aim of the study was to explore the differences in gene expression profiles comparing PsA patients without cutaneous psoriasis (PsA-only) and PsA patients with cutaneous psoriasis (PsA/PsC). The secondary aim was to describe the transcriptional patterns in PsA patients compared with healthy controls.

Methods

The study applied single-cell RNA sequencing (scRNAseq) using the BD Rhapsody™ Single-Cell Analysis System to evaluate peripheral blood mononuclear cells (PBMCs) from 70 PsA patients and 10 healthy controls. Differential expression (DE) analysis and gene set enrichment analysis (GSEA) were applied to evaluate differentially expressed genes (DEGs) and enriched signaling pathways, respectively.

Results

The DE analysis and GSEA comparing PsA-only and PsA/PsC patients with healthy controls, respectively, revealed divergent results involving both innate and adaptive immune mechanisms, which might be associated with differences in the clinical phenotype. No DEGs were discovered in the direct comparison of PsA-only and PsA/PsC patients.

Discussion

The single-cell transcriptome profiling provided insight into the heterogeneity of PsA patients as the discovered DEGs and the GSEA did demonstrate differences in signaling associated with inflammation comparing PsA patients with and without cutaneous psoriasis.

The sentinels of coronary artery disease: heterogeneous monocytes

Monocytes are heterogeneous immune cells that play a crucial role in the inflammatory response during atherosclerosis, influencing the progression and outcome of the disease. In the pathogenesis of atherosclerotic diseases, such as coronary artery disease (CAD), monocytes not only serve as the initial sensors of endogenous and exogenous pathogenic factors, but also function as intermediators that bridge the circulatory system and localized lesions. In the bloodstream, heterogeneous monocytes, acting as sentinels, are rapidly recruited to atherosclerotic lesions, where they exhibit a heightened capacity to respond to various pathological stimuli upon detecting signals from damaged vascular endothelial cells. Clinical studies have demonstrated that the heterogeneity of monocytes in CAD patients presents both diversity and complexity, varying across different disease subtypes and pathological stages. This review explores the heterogeneity of monocytes in CAD, focusing on alterations in monocyte subset numbers, proportions, and the expression of functional receptors, as well as their correlations with clinical features. Additionally, we propose strategies to enhance the clinical utility value of monocyte heterogeneity and outline future research directions in the field of CAD. With the widespread application of high-parameter flow cytometry and single-cell sequencing technologies, it is anticipated that a comprehensive understanding of monocyte heterogeneity in CAD will be achieved, enabling the identification of disease-specific monocyte subtypes. This could offer new opportunities for improving the diagnosis and treatment of CAD.

Laboratory and clinical haemostatic aberrations in primary dermatologic disease: A review

Inflammatory dermatologic diseases have long been viewed as a "skin limited" disease process. Current literature on inflammatory dermatologic diseases investigates their relationship and influence on thromboembolic states and thromboembolic complications and the understanding of their pathophysiology and molecular mechanisms.Studies specifically discuss known inflammatory skin diseases including alopecia areata, vitiligo, psoriasis, hidradenitis suppurativa, atopic dermatitis, chronic spontaneous urticaria, and autoimmune bullous diseases, and their effects on systemic inflammation, associated cardiovascular comorbidities, and thromboembolic or hypercoagulable states. The limited current literature shows potential for links between inflammatory skin diseases and hypercoagulable states. Biomarkers such as F1 + 2, D-dimer, eosinophilic cationic protein, and PAI-1 are currently being studied to outline the mechanisms connecting inflammatory skin disease to the coagulation system. Further study and larger amounts of data are needed to draw definitive conclusions, especially when interpreting biomarkers alone such as PAI-1.The mechanisms, rates of systemic inflammation, and clinical outcomes of traditionally "skin limited" inflammatory diseases remain chronically understudied in dermatology. Many organ systems have well established connections between inflammatory disease and hypercoagulable states, but there are significant gaps in the literature regarding skin diseases. There is a significant need for comprehensive investigation of molecular mechanisms behind inflammatory dermatologic disease and hypercoagulability, how hypercoagulability effects clinical outcomes, and proper intervention to optimize patient outcomes.

Immune cell activity during anti-TNF treatment in patients with psoriasis and psoriatic arthritis

Psoriasis is a chronic, inflammatory skin disease characterized by a dysregulated immune response and systemic inflammation. Up to one-third of patients with psoriasis have psoriatic arthritis (PsA). Targeted treatment with antibodies neutralizing tumor necrosis factor can ameliorate both diseases. We here explored the impact of long-term infliximab treatment on the composition and activity status of circulating immune cells involved in chronic skin and joint inflammation. Immune cells were analyzed by multicolor flow cytometry. We measured markers of immune activation in peripheral blood mononuclear cell populations in 24 infliximab-treated patients with psoriasis/PsA compared to 32 healthy controls. We observed a significant decrease in the frequency of both peripheral natural killer (NK) cells and their subset CD56dimCD16+ NK cells in PsA compared to healthy controls and patients with psoriasis. The latter had a strong-positive correlation with psoriasis area severity index (PASI) in these patients, while CD56brightCD16- NK cells were negatively correlated with PASI. In addition, we observed an upregulation of CD69+ intermediate CD14+CD16+ and CD69+ classical CD14+CD16- monocytes in PsA and increased activity of CD38+ intermediate CD14+CD16+ monocytes in patients with psoriasis. Compared to healthy controls, psoriasis patients demonstrated shifts of the three B-cell subsets with a decrease in transitional CD27-CD38high B cells. Our exploratory study indicates a preserved pathophysiological process including continuous systemic inflammation despite clinical stability of the patients treated with infliximab.

Assessing systemic inflammatory markers in psoriasis: A retrospective study

BACKGROUND

Psoriasis is a chronic inflammatory disease often associated with serious cardiovascular comorbidities. The aim of this study was to investigate the systemic inflammatory burden in psoriasis by examining various inflammatory markers and to assess the relationship between these markers and the severity of the disease.

METHODS

This retrospective study was conducted on medical records of patients who visited the dermatology outpatient clinic between 1 January 2016 and 31 December 2022. The study included patients with psoriasis vulgaris and healthy volunteers. Demographic data, Psoriasis Area and Severity Index score, C-reactive protein, monocyte-high-density lipoprotein cholesterol ratio, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, systemic immune-inflammation index, and Systemic Inflammation Response Index were analysed and compared.

RESULTS

A total of 278 psoriasis patients and 90 healthy volunteers were analysed. Compared to the control group, psoriasis patients showed significantly higher systemic immune-inflammation index, Systemic Inflammation Response Index, neutrophil-to-lymphocyte ratio, monocyte-high-density lipoprotein cholesterol ratio, serum C-reactive protein levels, neutrophil count, monocyte count, body mass index, and waist circumference (p < 0.001, p = 0.001, p < 0.001, p = 0.014, p < 0.001, p < 0.001, p = 0.046, p < 0.001, and p = 0.011, respectively). Among patients with severe psoriasis (Psoriasis Area and Severity Index >10), systemic immune-inflammation index, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and serum C-reactive protein levels were significantly higher compared to patients with mild/moderate psoriasis (Psoriasis Area and Severity Index ≤10). In the ROC curve analysis, the optimal cut-off (AUC, sensitivity, specificity) values for neutrophil-to-lymphocyte ratio, systemic immune-inflammation index, and platelet-to-lymphocyte ratio were found to be 2.11 (0.592, 62%, 57%), 552.9 (0.579, 61%, 58%), and 111.9 (0.578, 64%, 46%), respectively. The inflammatory parameters that showed correlation with Psoriasis Area and Severity Index were systemic immune-inflammation index, Systemic Inflammation Response Index, neutrophil-to-lymphocyte ratio, monocyte-high-density lipoprotein cholesterol ratio, monocyte-to-lymphocyte ratio, and C-reactive protein.

CONCLUSION

The findings of this study suggest that systemic immune-inflammation index, Systemic Inflammation Response Index, neutrophil-to-lymphocyte ratio, monocyte-high-density lipoprotein cholesterol ratio, and C-reactive protein values have the potential to serve as simple and cost-effective markers for assessing the inflammatory burden in individuals with psoriasis.

IL-10 induces activated phenotypes of monocytes observed in virally-suppressed HIV-1-infected individuals

Despite viral suppression by effective combined antiretroviral therapy, HIV-1-infected individuals have an increased risk of non-AIDS-related overall morbidity, which is due to the persistent chronic inflammation exemplified by the activation of monocytes, such as increased CD16high subset, and elevated plasma level of soluble CD163 (sCD163) and soluble CD14 (sCD14). Here, we show that IL-10, which has been recognized as anti-inflammatory, induces these activated phenotypes of monocytes in vitro. IL-10 increased CD16high monocytes, which was due to the upregulation of CD16 mRNA expression and completely canceled by an inhibitor of Stat3. Moreover, IL-10 increased the production of sCD163 and sCD14 by monocytes, which was consistent with the upregulation of cell surface expression of CD163 and CD14, and mRNA expression of CD163. However, unlike the IL-10-indeuced upregulation of CD16, that of CD14 was minimally affected by the Stat3 inhibitor. Furthermore, the IL-10-induced upregulation of CD163 protein and mRNA was partially inhibited by the Stat3 inhibitor, but completely canceled by an inhibitor of AMPK, an upstream kinase of Stat3 and PI3K/Akt/mTORC1 pathways. In this study, we also found that HIV-1 pathogenic protein Nef, which is known to persist in plasma of virally-suppressed individuals, induced IL-10 production in monocyte-derived macrophages. Our results may suggest that IL-10, which is inducible by Nef-activated macrophages, is one of drivers for activated phenotypes of monocytes in virally-suppressed individuals, and that IL-10 induces the increased CD16high monocytes and elevated level of sCD163 and sCD14 through the activation of different signaling pathways.

Unveiling multifaceted roles of myeloid innate immune cells in the pathogenesis of psoriasis

Psoriasis is a chronic inflammatory skin disease occurring worldwide. Initially viewed as a keratinocyte disorder, psoriasis is now recognized to involve a complex interplay between genetic predisposition, environmental triggers, and a dysregulated immune system, with a significant role of CD4+ T cells producing IL-17. Recent genetic studies have identified susceptibility loci that underscore the importance of innate immune responses, particularly the roles of myeloid cells, such as dendritic cells, macrophages, and neutrophils. These cells initiate and sustain inflammation through cytokine production triggered by external stimuli. They influence keratinocyte behavior and interact with adaptive immune cells. Recent techniques have further revealed the heterogeneity of myeloid cells in psoriatic lesions, highlighting the contributions of less-studied subsets, such as eosinophils and mast cells. This review examines the multifaceted roles of myeloid innate immune cells in psoriasis, emphasizing their functional diversity in promoting psoriatic inflammation. It also describes current treatment targeting myeloid innate immune cells and explores potential new therapeutic strategies based on the functional characteristics of these subsets. Future research should focus on the detailed characterization of myeloid subsets and their interactions to develop targeted treatments that address the complex immune landscape of psoriasis.

Cellular indexing of transcriptomes and epitopes (CITE-Seq) in hidradenitis suppurativa identifies dysregulated cell types in peripheral blood and facilitates diagnosis via machine learning

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition characterized by painful nodules, abscesses, and scarring, predominantly affecting intertriginous regions and it is often underdiagnosed. This study aimed to utilize single cell RNA and cell-surface protein sequencing (CITE-Seq) to delineate the immune composition of circulating cells in Hidradenitis suppurativa (HS) peripheral blood compared to healthy controls. CITE-Seq was used to analyze the gene and protein expression profiles of peripheral blood mononuclear cells (PBMCs) from 9 HS and 29 healthy controls. The study identified significant differences cell composition between HS patients and healthy controls, including increased proportions of CD14+ and CD16+ monocytes, cDC2, plasmablasts, and proliferating CD4+ T cells in HS patients. Differential expression analysis revealed upregulation of inflammatory markers such as TNF, IL1B, and NF-κB in monocytes, as well as chemokines and cell adhesion molecules involved in immune cell recruitment and tissue infiltration. Pathway enrichment analysis highlighted the involvement of IL-17, IL-26 and TNF signaling pathways in HS pathogenesis. Machine learning identified key markers for diagnostics and therapeutic development. The findings also support the potential for machine learning models to aid in the diagnosis of HS based on immune cell markers. These insights may inform future therapeutic strategies targeting specific immune pathways in HS.

Circulating Monocytes Are Predictive and Responsive in Moderate-to-Severe Plaque Psoriasis Subjects Treated with Apremilast

Monocytes play a critical role in the inflammation associated with psoriasis, and their abnormalities have been reported as biomarkers of cardiovascular event risk, a psoriasis comorbidity. Monocytic cells in chronic inflammatory disorders express elevated levels of cAMP phosphodiesterase. Restoring cAMP levels using the oral cAMP phosphodiesterase-4 inhibitor, apremilast, improves clinical outcomes for a subset of patients with psoriasis. We asked whether aberrant monocyte subsets or transcriptomic pathways can function as biomarkers of psoriasis endotypes that can predict enhanced clinical responses to cAMP phosphodiesterase inhibition. A 16-week open-label study of 22 patients with monocyte flow cytometric and transcriptomic analysis was performed. Subjects with elevated hyperadhesive monocyte doublets at baseline were more likely to be responders to apremilast (P < .0001); 82% of subjects with elevated hyperadhesive monocyte doublets achieved 50% reduction in PASI compared with 46% in those without elevated doublets. We observed a significant reduction in hyperadhesive monocyte-containing doublets and monocyte-platelet aggregates, suggesting an effect of apremilast on the adhesiveness of blood monocytes during chronic inflammation. Monocyte differentially expressed gene transcripts predictive of clinical response uncovered pharmacoendotypes with distinct patterns of nucleotide metabolism, energetics, and differentiation. Further study to understand the basis of drug responsiveness and to develop an apremilast psoriasis treatment algorithm using monocyte-refined gene expression is required to validate and become practical in clinical use, offering patients a test that personalizes their likelihood of clinical response.

Relationship between circulating white blood cell count and inflammatory skin disease: a bidirectional mendelian randomization study

Observational studies have shown a strong association between circulating white blood cell counts (WBC) and inflammatory skin diseases such as acne and psoriasis. However, the causal nature of this relationship is unclear. We performed a two-way two-sample Mendelian randomization (MR) analysis to investigate potential causal relationships between leukocytes and inflammatory skin diseases. The circulating white blood cell count, basophil cell count, leukocyte cell count, lymphocyte cell count, eosinophil cell count, and neutrophil cell count data were obtained from the Blood Cell Consortium (BCX). The data for inflammatory skin disorders, including acne, atopic dermatitis (AD), hidradenitis suppurativa (HS), psoriasis, and seborrheic dermatitis (SD), were obtained from the FinnGen Consortium R10. The primary analysis utilized inverse variance weighting (IVW) along with additional methods such as MR-Egger, weighted mode, and weighted median estimator. To assess heterogeneity among instrument variables, Cochran's Q test was employed, while MR-Egger intercept and MR-PRESSO were used to test for horizontal pleiotropy. IVW demonstrated that an elevated monocyte count was significantly associated with a decreased risk of psoriasis (OR = 0.897, 95% CI: 0.841-0.957, P = 0.001, FDR = 0.016). Additionally, an increased eosinophil count was causally associated with a higher risk of AD (OR = 1.188, 95% CI: 1.093-1.293, P = 0.000, FDR = 0.002). No inverse causal relationship between inflammatory skin disease and circulating white blood cell count was found. In conclusion, this study provides evidence that increased monocyte count is associated with a reduced risk of psoriasis and that there is a causal relationship between increased eosinophil counts and an increased risk of AD. These findings help us understand the potential causal role of specific white blood cell counts in the development of inflammatory skin diseases.

LL37/self-DNA complexes mediate monocyte reprogramming

LL37 alone and in complex with self-DNA triggers inflammatory responses in myeloid cells and plays a crucial role in the development of systemic autoimmune diseases, like psoriasis and systemic lupus erythematosus. We demonstrated that LL37/self-DNA complexes induce long-term metabolic and epigenetic changes in monocytes, enhancing their responsiveness to subsequent stimuli. Monocytes trained with LL37/self-DNA complexes and those derived from psoriatic patients exhibited heightened glycolytic and oxidative phosphorylation rates, elevated release of proinflammatory cytokines, and affected naïve CD4+ T cells. Additionally, KDM6A/B, a demethylase of lysine 27 on histone 3, was upregulated in psoriatic monocytes and monocytes treated with LL37/self-DNA complexes. Inhibition of KDM6A/B reversed the trained immune phenotype by reducing proinflammatory cytokine production, metabolic activity, and the induction of IL-17-producing T cells by LL37/self-DNA-treated monocytes. Our findings highlight the role of LL37/self-DNA-induced innate immune memory in psoriasis pathogenesis, uncovering its impact on monocyte and T cell dynamics.

Metagenomics reveals unique gut mycobiome biomarkers in psoriasis

PURPOSE

In present, the diagnosis of psoriasis is mainly based on the patient's typical clinical manifestations, dermoscopy and skin biopsy, and unlike other immune diseases, psoriasis lacks specific indicators in the blood. Therefore, we are required to search novel biomarkers for the diagnosis of psoriasis.

METHODS

In this study, we analyzed the composition and the differences of intestinal fungal communities composition between psoriasis patients and healthy individuals in order to find the intestinal fungal communities associated with the diagnosis of psoriasis. We built a machine learning model and identified potential microbial markers for the diagnosis of psoriasis.

RESULTS

The results of AUROC (area under ROC) showed that Aspergillus puulaauensis (AUROC = 0.779), Kazachstania africana (AUROC = 0.750) and Torulaspora delbrueckii (AUROC = 0.745) had high predictive ability (AUROC > 0.7) for predicting psoriasis, While Fusarium keratoplasticum (AUROC = 0.670) was relatively lower (AUROC < 0.7).

CONCLUSION

The strategy based on the prediction of intestinal fungal communities provides a new idea for the diagnosis of psoriasis and is expected to become an auxiliary diagnostic method for psoriasis.

Associations of novel complete blood count-derived inflammatory markers with psoriasis: a systematic review and meta-analysis

Psoriasis is an immune-mediated disorder which primarily affects skin and has systemic inflammatory involvement. Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and monocyte-to-lymphocyte ratio (MLR) are novel complete blood count (CBC)-derived markers which can reflect systemic inflammation. This study aimed to systematically investigate the associations of NLR, PLR, SII, and MLR with psoriasis. This study was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. A comprehensive search of Pubmed, Embase, Scopus, and Google Scholar was conducted for relevant studies. Observational studies evaluating the correlations of NLR, PLR, SII, or MLR with psoriasis were included. The primary outcomes were the associations of these inflammatory markers with the presence and severity of psoriasis. The random-effect model was applied for meta-analysis. 36 studies comprising 4794 psoriasis patients and 55,121 individuals in total were included in the meta-analysis. All inflammatory markers were significantly increased in psoriasis groups compared to healthy controls (NLR: MD = 0.59, 95% CI: 0.47-0.7; PLR: MD = 15.53, 95% CI: 8.48-22.58; SII: MD = 111.58, 95% CI: 61.49-161.68; MLR: MD = 0.034, 95% CI: 0.021-0.048; all p < 0.001). Between-group mean differences in NLR and PLR were positively correlated with the mean scores of Psoriasis Area Severity Index (NLR: p = 0.041; PLR: p = 0.021). NLR, PLR, SII, and MLR are associated with the presence of psoriasis. NLR and PLR serve as significant indicators of psoriasis severity. These novel CBC-derived markers constitute potential targets in the screening and monitoring of psoriasis.

Insights into Autophagic Machinery and Lysosomal Function in Cells Involved in the Psoriatic Immune-Mediated Inflammatory Cascade

Impaired autophagy, due to the dysfunction of lysosomal organelles, contributes to maladaptive responses by pathways central to the immune system. Deciphering the immune-inflammatory ecosystem is essential, but remains a major challenge in terms of understanding the mechanisms responsible for autoimmune diseases. Accumulating evidence implicates a role that is played by a dysfunctional autophagy-lysosomal pathway (ALP) and an immune niche in psoriasis (Ps), one of the most common chronic skin diseases, characterized by the co-existence of autoimmune and autoinflammatory responses. The dysregulated autophagy associated with the defective lysosomal system is only one aspect of Ps pathogenesis. It probably cannot fully explain the pathomechanism involved in Ps, but it is likely important and should be seriously considered in Ps research. This review provides a recent update on discoveries in the field. Also, it sheds light on how the dysregulation of intracellular pathways, coming from modulated autophagy and endolysosomal trafficking, characteristic of key players of the disease, i.e., skin-resident cells, as well as circulating immune cells, may be responsible for immune impairment and the development of Ps.

DeepIFC: Virtual fluorescent labeling of blood cells in imaging flow cytometry data with deep learning

Imaging flow cytometry (IFC) combines flow cytometry with microscopy, allowing rapid characterization of cellular and molecular properties via high-throughput single-cell fluorescent imaging. However, fluorescent labeling is costly and time-consuming. We present a computational method called DeepIFC based on the Inception U-Net neural network architecture, able to generate fluorescent marker images and learn morphological features from IFC brightfield and darkfield images. Furthermore, the DeepIFC workflow identifies cell types from the generated fluorescent images and visualizes the single-cell features generated in a 2D space. We demonstrate that rarer cell types are predicted well when a balanced data set is used to train the model, and the model is able to recognize red blood cells not seen during model training as a distinct entity. In summary, DeepIFC allows accurate cell reconstruction, typing and recognition of unseen cell types from brightfield and darkfield images via virtual fluorescent labeling.

Herring roe oil in treatment of psoriasis - influence on immune cells and cytokine network

Background

Psoriasis is a chronic immune-mediated skin disease with systemic inflammation and comorbidities. Although the disease severity may vary over time, many patients suffer from mild to moderate disease. Often local treatment will be sufficient to control the symptoms, but they may have several side effects. ω-3 polyunsaturated fatty acids have shown promising results in clinical trials with mild-to-moderate psoriasis.

Methods

We explored the impact of phospholipid bound docosahexaenoic acid and eicosapentaenoic acid in a 3:1 ratio on immune cells and cytokine networks in peripheral blood of patients with psoriasis. We investigated the inter-relation of plasma cytokine levels and disease severity in 58 patients, and explored the status of circulating immune cell activity in 18 patients with non-severe psoriasis before and during herring roe oil supplementation. Plasma concentration of 22 cytokines was measured by Luminex technology and circulating immune cells were analyzed by multicolor flow cytometry.

Results

CCL2 levels decreased over time, and IFN-γR1 increased, possibly related to the action of ω-3 polyunsaturated fatty acids. We observed a shift from naïve to effector CD4+ T cells and decreases of CD38 expression on CD4+ and CD8+ T cells, CD56bright NK cells and CD14+CD16- classical monocytes.

Conclusions

These findings support the beneficial effect of herring roe oil supplementation.

Sericin coated thin polymeric films reduce keratinocyte proliferation via the mTOR pathway and epidermal inflammation through IL17 signaling in psoriasis rat model

Therapeutic treatment forms can play significant roles in resolving psoriatic plaques or promoting wound repair in psoriatic skin. Considering the biocompatibility, mechanical strength, flexibility, and adhesive properties of silk fibroin sheets/films, it is useful to combine them with anti-psoriatic agents and healing stimulants, notably silk sericin. Here, we evaluate the curative properties of sericin-coated thin polymeric films (ScF) fabricated from silk fibroin, using an imiquimod-induced psoriasis rat model. The film biocompatibility and psoriatic wound improvement capacity was assessed. A proteomics study was performed to understand the disease resolving mechanisms. Skin-implantation study exhibited the non-irritation property of ScF films, which alleviate eczema histopathology. Immunohistochemical and gene expression revealed the depletion of β-defensin, caspase-3 and -9, TNF-α, CCL-20, IL-1β, IL-17, TGF-β, and Wnt expressions and S100a14 mRNA level. The proteomics study suggested that ScF diminish keratinocyte proliferation via the mTOR pathway by downregulating mTOR protein, corresponding to the modulation of TNF-α, Wnt, and IL-1β levels, leading to the enhancement of anti-inflammatory environment by IL-17 downregulation. Hematology data demonstrated the safety of using these biomaterials, which provide a potential therapeutic-option for psoriasis treatment due to desirable effects, especially anti-proliferation and anti-inflammation, functioning via the mTOR pathway and control of IL-17 signaling.

The integration of large-scale public data and network analysis uncovers molecular characteristics of psoriasis

In recent years, a growing interest in the characterization of the molecular basis of psoriasis has been observed. However, despite the availability of a large amount of molecular data, many pathogenic mechanisms of psoriasis are still poorly understood. In this study, we performed an integrated analysis of 23 public transcriptomic datasets encompassing both lesional and uninvolved skin samples from psoriasis patients. We defined comprehensive gene co-expression network models of psoriatic lesions and uninvolved skin. Moreover, we curated and exploited a wide range of functional information from multiple public sources in order to systematically annotate the inferred networks. The integrated analysis of transcriptomics data and co-expression networks highlighted genes that are frequently dysregulated and show aberrant patterns of connectivity in the psoriatic lesion compared with the unaffected skin. Our approach allowed us to also identify plausible, previously unknown, actors in the expression of the psoriasis phenotype. Finally, we characterized communities of co-expressed genes associated with relevant molecular functions and expression signatures of specific immune cell types associated with the psoriasis lesion. Overall, integrating experimental driven results with curated functional information from public repositories represents an efficient approach to empower knowledge generation about psoriasis and may be applicable to other complex diseases.

Dendritic Cells and Macrophages in the Pathogenesis of Psoriasis

Psoriasis is a chronic inflammatory skin disease characterized by scaly indurated erythema. This disease impairs patients’ quality of life enormously. Pathological findings demonstrate proliferation and abnormal differentiation of keratinocytes and massive infiltration of inflammatory immune cells. The pathogenesis of psoriasis is complicated. Among immune cells, dendritic cells play a pivotal role in the development of psoriasis in both the initiation and the maintenance phases. In addition, it has been indicated that macrophages contribute to the pathogenesis of psoriasis especially in the initiation phase, although studies on macrophages are limited. In this article, we review the roles of dendritic cells and macrophages in the pathogenesis of psoriasis.

Targeting folate receptor beta on monocytes/macrophages renders rapid inflammation resolution independent of root causes

Provoked by sterile/nonsterile insults, prolonged monocyte mobilization and uncontrolled monocyte/macrophage activation can pose imminent or impending harm to the affected organs. Curiously, folate receptor beta (FRβ), with subnanomolar affinity for the vitamin folic acid (FA), is upregulated during immune activation in hematopoietic cells of the myeloid lineage. This phenomenon has inspired a strong interest in exploring FRβ-directed diagnostics/therapeutics. Previously, we have reported that FA-targeted aminopterin (AMT) therapy can modulate macrophage function and effectively treat animal models of inflammation. Our current investigation of a lead compound (EC2319) leads to discovery of a highly FR-specific mechanism of action independent of the root causes against inflammatory monocytes. We further show that EC2319 suppresses interleukin-6/interleukin-1β release by FRβ⁺ monocytes in a triple co-culture leukemic model of cytokine release syndrome with anti-CD19 chimeric antigen receptor T cells. Because of its chemical stability and metabolically activated linker, EC2319 demonstrates favorable pharmacokinetic characteristics and cross-species translatability to support future pre-clinical and clinical development.

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Functional folate receptor beta is transiently expressed on inflammatory monocytes

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EC2319 is an enhancement of traditional dihydrofolate reductase inhibitors

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EC2319 anti-monocyte activity correlates with local/systemic therapeutic benefit

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EC2319 inhibition of cytokine release suggests emergency use for hyperinflammation

Immune Response in Severe and Non-Severe Coronavirus Disease 2019 (COVID-19) Infection: A Mechanistic Landscape

The mechanisms underlying the immune remodeling and severity response in coronavirus disease 2019 (COVID-19) are yet to be fully elucidated. Our comprehensive integrative analyses of single-cell RNA sequencing (scRNAseq) data from four published studies, in patients with mild/moderate and severe infections, indicate a robust expansion and mobilization of the innate immune response and highlight mechanisms by which low-density neutrophils and megakaryocytes play a crucial role in the cross talk between lymphoid and myeloid lineages. We also document a marked reduction of several lymphoid cell types, particularly natural killer cells, mucosal-associated invariant T (MAIT) cells, and gamma-delta T (γδT) cells, and a robust expansion and extensive heterogeneity within plasmablasts, especially in severe COVID-19 patients. We confirm the changes in cellular abundances for certain immune cell types within a new patient cohort. While the cellular heterogeneity in COVID-19 extends across cells in both lineages, we consistently observe certain subsets respond more potently to interferon type I (IFN-I) and display increased cellular abundances across the spectrum of severity, as compared with healthy subjects. However, we identify these expanded subsets to have a more muted response to IFN-I within severe disease compared to non-severe disease. Our analyses further highlight an increased aggregation potential of the myeloid subsets, particularly monocytes, in COVID-19. Finally, we provide detailed mechanistic insights into the interaction between lymphoid and myeloid lineages, which contributes to the multisystemic phenotype of COVID-19, distinguishing severe from non-severe responses.

New Frontiers in Psoriatic Disease Research, Part I: Genetics, Environmental Triggers, Immunology, Pathophysiology, and Precision Medicine

Psoriasis is a chronic inflammatory condition characterized by systemic immune dysregulation. Over the past several years, advances in genetics, microbiology, immunology, and mouse models have revealed the complex interplay between the heritable and microenvironmental factors that drive the development of psoriatic inflammation. In the first of this two-part review series, the authors will discuss the newest insights into the pathogenesis of psoriatic disease and highlight how the evolution of these scientific fields has paved the way for a more personalized approach to psoriatic disease treatment.

A Two-Stage Flow Cytometry Strategy to Distinguish Single Cells from Doublets in Heterogeneous Cell Mixtures and Improve Cell Cluster Identification: Application to Human Monocyte Subpopulations

Flow cytometry is a powerful method, widely used to identify cell types present in tissues, to describe their phenotypes, and to purify cells for functional analyses. As a single cell technique, flow cytometry relies on identifying and excluding cell doublets and aggregates present in samples in the initial gating steps. This identification is based on detection of events generating electrical pulses falling outside of linear variations of pulse height, width, and area in a singlet population with increasing cell sizes. In heterogeneous cell mixtures, however, with cell types varying extensively in size and granularity, exclusion of doublets has the risk of removing single cells that co-localize with doublets of another cell type. This is particularly the case when doublets of a smaller cell type overlap with large cells of a distinct, larger cell type. Here, we describe a gating method to reduce this risk. In this protocol, initial gating steps aim to segregate cells according to physical characteristics (such as size and granularity) and gene expression properties in order to obtain more homogeneous cell clusters. Doublet exclusion is then performed separately in each cluster, minimizing the risk of confusion between single cells and doublets. To illustrate this protocol, human blood monocytes are separated and analyzed. By implementing this protocol, we were able to reveal the existence of a population of large monocytes previously unrecognized using conventional gating strategies. In subsequent functional assays, we have shown that this novel population exhibits unique inflammatory responses, highlighting the need and pertinence of this approach to identify and characterize infrequent-yet functionally relevant-cell populations present in complex cell mixtures. © 2021 Wiley Periodicals LLC. Basic Protocol: Distinguishing single cells from doublets in heterogeneous cell mixtures by flow cytometry.

Therapeutic Development Based on the Immunopathogenic Mechanisms of Psoriasis

Psoriasis, a complex inflammatory autoimmune skin disorder that affects 2–3% of the global population, is thought to be genetically predetermined and induced by environmental and immunological factors. In the past decades, basic and clinical studies have significantly expanded knowledge on the molecular, cellular, and immunological mechanisms underlying the pathogenesis of psoriasis. Based on these pathogenic mechanisms, the current disease model emphasizes the role of aberrant Th1 and Th17 responses. Th1 and Th17 immune responses are regulated by a complex network of different cytokines, including TNF-α, IL-17, and IL-23; signal transduction pathways downstream to the cytokine receptors; and various activated transcription factors, including NF-κB, interferon regulatory factors (IRFs), and signal transducer and activator of transcriptions (STATs). The biologics developed to specifically target the cytokines have achieved a better efficacy and safety for the systemic management of psoriasis compared with traditional treatments. Nevertheless, the current therapeutics can only alleviate the symptoms; there is still no cure for psoriasis. Therefore, the development of more effective, safe, and affordable therapeutics for psoriasis is important. In this review, we discussed the current trend of therapeutic development for psoriasis based on the recent discoveries in the immune modulation of the inflammatory response in psoriasis.

Platelets: Underestimated Regulators of Autoinflammation in Psoriasis

Platelets have long been known as mediators of hemostasis and, more recently, as mediators of thromboinflammation, although their physiopathological role has mostly been investigated in the context of disease of internal organs, such as liver and kidney, or systemic disorders. Of late, exciting recent data suggest that platelets may also play a role in inflammation at distal sites such as the skin: recent studies show that platelets, by engaging polymorphonuclear neutrophils (PMNs), contribute to local inflammation in the frequent skin disorder, psoriasis. In an experimental model, systemic depletion of platelets drastically attenuated skin inflammation by preventing PMN infiltration of the skin. A broader role of platelets in different types of skin inflammation is therefore likely, and in this paper, we specifically review recent advances in psoriasis. Special emphasis is given to the crosstalk with systemic platelet effects, which may be of interest in psoriasis-related cardiovascular comorbidities. Furthermore, we discuss the potential for platelet-centered interventions in the therapy for psoriasis.

Macrophages in dermatology: pathogenic roles and targeted therapeutics

The field of macrophage biology is rapidly growing. Recent studies have shifted focus from classic wound healing roles to newly identified roles in dermatologic pathology. These studies have identified pathogenic roles of macrophages in relatively common conditions, such as psoriasis, skin cancer, and cutaneous T-cell lymphoma. Selective depletion of these cells or their associated cytokines leads to improved clinical outcome. Herein, we review recent animal and human studies that have elucidated novel pathogenic roles of macrophages in conditions frequently encountered by dermatologists and discuss clinically relevant macrophage-targeted therapies.

Quality of life of patients living with psoriasis: a qualitative study

BACKGROUND

Psoriasis is a multifactorial inflammatory disease prevalent in dermatology. We aimed to understand the perceptions of patients living with psoriasis in relation to their quality of life and to identify aspects to improve it.

METHODS

This is qualitative research carried out in a dermatology outpatient clinic of the São Paulo State University (UNESP) medical school, Botucatu, Brazil, with 81 psoriasis patients. The interviews were transcribed and analysed using the Discourse of the Collective Subject method (DCS).

RESULTS

Quality of life was linked to well-being, happiness, leisure, good food and financial stability. However, disease symptoms, social and clothing restrictions, impairment of professional activities and the absence of a cure, negatively influenced their perceptions. Suggestions for improvements included an increase of public awareness, stress reduction, disease acceptance and multidisciplinary care.

CONCLUSION

The meanings of quality of life revealed by the participants are subjective, multidimensional, linked to moments experienced by them and to the health-disease process. Public health policies promoting reduction in social stigma and stress as well as multidisciplinary approaches towards care can contribute to improvements of QoL in psoriasis.

Psoriasis and Psoriatic Arthritis Cardiovascular Disease Endotypes Identified by Red Blood Cell Distribution Width and Mean Platelet Volume

In a subset of psoriasis (PsO) and psoriatic arthritis (PsA) patients, the skin and/or joint lesions appear to generate biologically significant systemic inflammation. Red cell distribution width (RDW) and mean platelet volume (MPV) are readily available clinical tests that reflect responses of the bone marrow and/or plasma thrombogenicity (e.g., inflammation), and can be markers for major adverse cardiac events (MACE). We aimed to evaluate if RDW and MPV may be employed as inexpensive, routinely obtained biomarkers in predicting myocardial infarction (MI), atrial fibrillation (AF), and chronic heart failure (CHF) in psoriatic and psoriatic arthritis patients. The study was divided into two parts: (a) case control study employing big data (Explorys) to assess MPV and RDW in psoriasis, psoriatic arthritis and control cohorts; (b) a clinical observational study to validate the predictive value of RDW and to evaluate RDW response to anti-psoriatic therapies. We used Explorys, an aggregate electronic database, to identify psoriatic patients with available MPV and RDW data and compared them to gender and age matched controls. The incidence of myocardial infarction (MI), atrial fibrillation (AF), and chronic heart failure (CHF) was highest among patients with both elevated RDW and MPV, followed by patients with high RDW and normal MPV. RDW elevation among PsA patients was associated with an increased risk of MI, AF, and CHF. In a local clinical cohort, high RDWs were concentrated in a subset of patients who also had elevated circulating resistin levels. Among a small subset of participants who were treated with various systemic and biologic therapies, and observed over a year, and in whom RDW was elevated at baseline, a sustained response to therapy was associated with a decrease in RDW. RDW and MPV, tests commonly contained within routine complete blood count (CBC), may be a cost-effective manner to identify PsO and PsA patients at increased risk of MACE.

Platelets Aggregate With Neutrophils and Promote Skin Pathology in Psoriasis

Psoriasis is a frequent systemic inflammatory autoimmune disease characterized primarily by skin lesions with massive infiltration of leukocytes, but frequently also presents with cardiovascular comorbidities. Especially polymorphonuclear neutrophils (PMNs) abundantly infiltrate psoriatic skin but the cues that prompt PMNs to home to the skin are not well-defined. To identify PMN surface receptors that may explain PMN skin homing in psoriasis patients, we screened 332 surface antigens on primary human blood PMNs from healthy donors and psoriasis patients. We identified platelet surface antigens as a defining feature of psoriasis PMNs, due to a significantly increased aggregation of neutrophils and platelets in the blood of psoriasis patients. Similarly, in the imiquimod-induced experimental in vivo mouse model of psoriasis, disease induction promoted PMN-platelet aggregate formation. In psoriasis patients, disease incidence directly correlated with blood platelet counts and platelets were detected in direct contact with PMNs in psoriatic but not healthy skin. Importantly, depletion of circulating platelets in mice in vivo ameliorated disease severity significantly, indicating that both PMNs and platelets may be relevant for psoriasis pathology and disease severity.

IL-36γ Is a Strong Inducer of IL-23 in Psoriatic Cells and Activates Angiogenesis

The IL-1 family member cytokine IL-36γ is recognised as key mediator in the immunopathology of psoriasis, hallmarks of which involve the activation of both resident and infiltrating inflammatory myeloid cells and aberrant angiogenesis. This research demonstrates a role for IL-36γ in both myeloid activation and angiogenesis. We show that IL-36γ induces the production of psoriasis-associated cytokines from macrophages (IL-23 and TNFα) and that this response is enhanced in macrophages from psoriasis patients. This effect is specific for IL-36γ and could not be mimicked by other IL-1 family cytokines such as IL-1α. IL-36γ was also demonstrated to induce endothelial tube formation and branching, in a VEGF-A-dependent manner. Furthermore, IL-36γ-stimulated macrophages potently activated endothelial cells and led to increased adherence of monocytes, effects that were markedly more pronounced for psoriatic macrophages. Interestingly, regardless of stimulus, psoriasis monocytes showed increased adherence to both the stimulated and unstimulated endothelium when compared with monocytes from healthy individuals. Collectively, these findings show that IL-36γ has the potential to enhance endothelium directed leucocyte infiltration into the skin and strengthen the IL-23/IL-17 pathway adding to the growing evidence of pathogenetic roles for IL-36γ in psoriatic responses. Our findings also point to a cellular response, which could potentially explain cardiovascular comorbidities in psoriasis in the form of endothelial activation and increased monocyte adherence.

Up-regulated expression of CD86 on circulating intermediate monocytes correlated with disease severity in psoriasis

BACKGROUND

The number of intermediate monocytes (CD14⁺⁺CD16⁺) increases in many inflammatory conditions. However, it is not yet known which functional markers expressed by these populations are linked to the pathogenesis of psoriasis.

OBJECTIVES

We evaluated the expression of functional markers on circulating intermediate monocytes. Our goal was to correlate specific populations and their markers with the clinical severity of psoriasis.

METHODS

A cohort of 43 psoriatic patients was subjected to analysis. The proportion of intermediate monocytes with CD86 expression was evaluated by flow cytometry. Serum beta defensin-2 levels were measured by ELISA. Immunofluorescent staining was performed in order to identify the presence of CD14⁺CD16⁺ cells that co-expressed CD86 in affected skin tissues.

RESULTS

Upregulated expression of CD86 on the intermediate subset (but not the number of intermediate monocytes) correlated with clinical severity as measured by PASI scores and serum beta defensin-2 levels. Immunostaining also showed the presence of CD86⁺CD14⁺CD16⁺ cells in the epidermis and dermis of psoriatic plaques, which was associated with increased epidermal proliferation.

CONCLUSION

These results suggest that the expression of CD86 on circulating intermediate monocytes could be used as an index in clinical practice and provide novel insights into how these cells join a complex immune network under the pathological conditions of psoriasis.

The atopic dermatitis blood signature is characterized by increases in inflammatory and cardiovascular risk proteins

Beyond classic “allergic”/atopic comorbidities, atopic dermatitis (AD) emerges as systemic disease with increased cardiovascular risk. To better define serum inflammatory and cardiovascular risk proteins, we used an OLINK high-throughput proteomic assay to analyze moderate-to-severe AD (n = 59) compared to psoriasis (n = 22) and healthy controls (n = 18). Compared to controls, 10 proteins were increased in serum of both diseases, including Th1 (IFN-γ, CXCL9, TNF-β) and Th17 (CCL20) markers. 48 proteins each were uniquely upregulated in AD and psoriasis. Consistent with skin expression, AD serum showed up-regulation of Th2 (IL-13, CCL17, eotaxin-1/CCL11, CCL13, CCL4, IL-10), Th1 (CXCL10, CXCL11) and Th1/Th17/Th22 (IL-12/IL-23p40) responses. Surprisingly, some markers of atherosclerosis (fractalkine/CX3CL1, CCL8, M-CSF, HGF), T-cell development/activation (CD40L, IL-7, CCL25, IL-2RB, IL-15RA, CD6) and angiogenesis (VEGF-A) were significantly increased only in AD. Multiple inflammatory pathways showed stronger enrichment in AD than psoriasis. Several atherosclerosis mediators in serum (e.g. E-selectin, PI3/elafin, CCL7, IL-16) correlated with SCORAD, but not BMI. Also, AD inflammatory mediators (e.g. MMP12, IL-12/IL-23p40, CXCL9, CCL22, PI3/Elafin) correlated between blood and lesional as well as non-lesional skin. Overall, the AD blood signature was largely different compared to psoriasis, with dysregulation of inflammatory and cardiovascular risk markers, strongly supporting its systemic nature beyond atopic/allergic association.

Interleukin 6 regulates psoriasiform inflammation-associated thrombosis

Psoriasis patients are at increased risk of heart attack and stroke and have elevated MRP8/14 levels that predict heart attack. The KC-Tie2 psoriasiform mouse model exhibits elevated MRP8/14 and is prothrombotic. Mrp14^-/- mice, in contrast, are protected from thrombosis, but, surprisingly, KC-Tie2xMrp14^-/- mice remain prothrombotic. Treating KC-Tie2xMrp14^-/- mice with anti-IL-23p19 antibodies reversed the skin inflammation, improved thrombosis, and decreased IL-6. In comparison, IL-6 deletion from KC-Tie2 animals improved thrombosis despite sustained skin inflammation, suggesting that thrombosis improvements following IL-23 inhibition occur secondary to IL-6 decreases. Psoriasis patient skin has elevated IL-6 and IL-6 receptor is present in human coronary atheroma, supporting a link between skin and distant vessel disease in patient tissue. Together, these results identify a critical role for skin-derived IL-6 linking skin inflammation with thrombosis, and shows that in the absence of IL-6 the connection between skin inflammation and thrombosis comorbidities is severed.

Feasibility of carotid artery PET/MRI in psoriasis patients

We report our initial experience of performing integrated PET/MR imaging of the carotid arteries in psoriatic patients. Eleven patients with psoriasis and ten controls underwent carotid PET/MRI. Following injection of the FDG tracer, 3d T1w gradient echo sequence (atMR) was obtained for attenuation correction of PET data. High resolution images of carotid artery were then obtained, including pre-and post-contrast T1-w, T2-w and proton-density images as well as TOF images followed by PET imaging of the torso. From the fused axial PET/MRI, the arterial wall SUVmax and TBRmax was quantified in each slice. MRI images were also evaluated for vessel wall volume, plaque and internal composition. SUVmax and TBRmax were respectively, 1.72 ± 0.38 & 1.17 ± 0.27 in L- CCA, 1.75 ± 0.39 & 1.24 ± 0.19 in R-CCA, 1.59 ± 0.24 & 1.08 ± 0.14 in L-ICA and 1.62 ± 0.27 & 1.15 ± 0.17 in R-ICA in psoriatic patients and 1.74 ± 0.22 & 1.28 ± 0.44 in L- CCA, 1.74 ± 0.33 & 1.07 ± 0.28 in R-CCA, 1.78 ± 0.32 & 1.29 ± 0.39 in L-ICA and 1.60 ± 0.29 & 0.98 ± 0.25 in R-ICA in the controls. No discrete plaques were identified in any of the vessel segments in MRI. PET/MRI is feasible in evaluation of carotid arteries in psoriatic patients.

Visualization of atherosclerosis as detected by coronary artery calcium and carotid intima-media thickness reveals significant atherosclerosis in a cross-sectional study of psoriasis patients in a tertiary care center

Background

Psoriasis is a chronic inflammatory disease of the skin and joints that may also have systemic inflammatory effects, including the development of cardiovascular disease (CVD). Multiple epidemiologic studies have demonstrated increased rates of CVD in psoriasis patients, although a causal link has not been established. A growing body of evidence suggests that sub-clinical systemic inflammation may develop in psoriasis patients, even from a young age. We aimed to evaluate the prevalence of atherosclerosis and identify specific clinical risk factors associated with early vascular inflammation.

Methods

We conducted a cross-sectional study of a tertiary care cohort of psoriasis patients using coronary artery calcium (CAC) score and carotid intima-media thickness (CIMT) to detect atherosclerosis, along with high sensitivity C-reactive protein (hsCRP) to measure inflammation. Psoriasis patients and controls were recruited from our tertiary care dermatology clinic. Presence of atherosclerosis was defined using validated numeric values within CAC and CIMT imaging. Descriptive data comparing groups was analyzed using Welch’s t test and Pearson Chi square tests. Logistic regression was used to analyze clinical factors associated with atherosclerosis, and linear regression to evaluate the relationship between psoriasis and hsCRP.

Results

296 patients were enrolled, with 283 (207 psoriatic and 76 controls) having all data for the hsCRP and atherosclerosis analysis. Atherosclerosis was found in 67.6 % of psoriasis subjects versus 52.6 % of controls; Psoriasis patients were found to have a 2.67-fold higher odds of having atherosclerosis compared to controls [95 % CI (1.2, 5.92); p = 0.016], after adjusting for age, gender, race, BMI, smoking, HDL and hsCRP. In addition, a non-significant trend was found between HsCRP and psoriasis severity, as measured by PASI, PGA, or BSA, again after adjusting for confounders.

Conclusions

A tertiary care cohort of psoriasis patients have a high prevalence of early atherosclerosis, increased hsCRP, and psoriasis remains a risk factor for the presence of atherosclerosis even after adjustment of key confounding clinical factors. Psoriasis may contribute to an accelerated systemic inflammatory cascade resulting in increased risk of CVD and CV events.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0947-0) contains supplementary material, which is available to authorized users.

Updates on cardiovascular comorbidities associated with psoriatic diseases: epidemiology and mechanisms

Psoriasis and psoriatic arthritis are associated with a significantly increased risk of cardiovascular risk factors and major adverse cardiovascular events (MACE). Active research is ongoing to elucidate this relationship between psoriatic diseases and cardiovascular comorbidities, as well as their shared pathogenic mechanisms. This review focuses on (1) the epidemiologic association between psoriasis and cardiovascular risk factors, (2) the epidemiologic association between psoriasis and MACE, (3) the epidemiologic association between psoriatic arthritis, cardiovascular risk factors, and MACE, and (4) proposed mechanisms for the contribution of psoriatic diseases to cardiovascular diseases. The proposed mechanisms for shared pathogenesis between psoriatic diseases and cardiovascular diseases are inflammation, insulin resistance, dyslipidemia, angiogenesis, oxidative stress, and endothelial dysfunction. There is complex interplay and overlap among these mechanisms and their contributions to shared pathogenesis. Future translational research is necessary to elucidate the link between psoriatic diseases and cardiovascular diseases. Such findings may be applied clinically to improve the lives of psoriasis patients.

Current knowledge on psoriasis and autoimmune diseases

Psoriasis is a prevalent, chronic inflammatory disease of the skin, mediated by crosstalk between epidermal keratinocytes, dermal vascular cells, and immunocytes such as antigen presenting cells (APCs) and T cells. Exclusive cellular “responsibility” for the induction and maintenance of psoriatic plaques has not been clearly defined. Increased proliferation of keratinocytes and endothelial cells in conjunction with APC/T cell/monocyte/macrophage inflammation leads to the distinct epidermal and vascular hyperplasia that is characteristic of lesional psoriatic skin. Despite the identification of numerous susceptibility loci, no single genetic determinant has been identified as responsible for the induction of psoriasis. Thus, numerous other triggers of disease, such as environmental, microbial and complex cellular interactions must also be considered as participants in the development of this multifactorial disease. Recent advances in therapeutics, especially systemic so-called “biologics” have provided new hope for identifying the critical cellular targets that drive psoriasis pathogenesis. Recent recognition of the numerous co-morbidities and other autoimmune disorders associated with psoriasis, including inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus suggest common signaling elements and cellular mediators may direct disease pathogenesis. In this review, we discuss common cellular pathways and participants that mediate psoriasis and other autoimmune disorders that share these cellular signaling pathways.

Increased, but Functionally Impaired, CD14(+) HLA-DR(-/low) Myeloid-Derived Suppressor Cells in Psoriasis: A Mechanism of Dysregulated T Cells

The clinical extent of psoriasis pathology is regulated in part by defects in immune networks, including a defect in the suppressive actions of regulatory T cells. Recently, CD14(+) HLA-DR(-/low) monocytic myeloid-derived suppressor cells (Mo-MDSCs) have been shown to suppress T-cell activation as one of their suppressive mechanisms. However, little is known about the role of Mo-MDSCs and their functional relationship to T-cell suppression in relation to human chronic immune-mediated inflammatory diseases, including psoriasis. Despite psoriasis being a hyperinflammatory condition, Mo-MDSCs were elevated in psoriatic patient peripheral blood mononuclear cells compared to nonpsoriatic healthy controls (2.6% vs. 0.9%, P < 0.002). Freshly isolated psoriatic Mo-MDSCs directly suppressed CD8 T-cell proliferation less efficiently than healthy control Mo-MDSCs. In addition, psoriatic Mo-MDSCs expressed reduced surface expression of programmed cell death protein 1 compared to healthy controls. Additional in vitro assays also demonstrated that psoriatic and control Mo-MDSCs both induce regulatory T-cell conversion from naïve T effector cells, but, importantly, the regulatory T cells induced by psoriatic Mo-MDSCs displayed decreased suppressive functionality. These results suggest that aberrations in psoriatic Mo-MDSCs prevent proper suppression of effector T-cell expansion and hamper the immune system's ability to correctly self-regulate.

Chronic, not acute, skin-specific inflammation promotes thrombosis in psoriasis murine models

Background

Psoriasis patients exhibit an increased risk of atherothrombotic events, including myocardial infarction and stroke. Clinical evidence suggests that psoriasis patients with early onset and more severe disease have the highest risk for these co-morbidities, perhaps due to the extent of body surface involvement, subsequent levels of systemic inflammation, or chronicity of disease. We sought to determine whether acute or chronic skin-specific inflammation was sufficient to promote thrombosis.

Methods

We used two experimental mouse models of skin-specific inflammation generated in either an acute (topical Aldara application onto wild-type C57Bl/6 mice for 5 days) or chronic (a genetically engineered K5-IL-17C mouse model of psoriasiform skin inflammation) manner. Arterial thrombosis was induced using carotid artery photochemical injury (Rose Bengal-green light laser) and carotid artery diameters were measured post-clot formation. We also examined measures of clot formation including prothrombin (PT) and activated partial thromboplastin time (aPTT). Skin inflammation was examined histologically and we profiled plasma-derived lipids. The number of skin-draining lymph-node (SDLN) and splenic derived CD11b⁺Ly6C^high pro-inflammatory monocytes and CD11b⁺Ly6G⁺ neutrophils was quantified using multi-color flow cytometry.

Results

Mice treated with topical Aldara for 5 days had similar carotid artery thrombotic occlusion times to mice treated with vehicle cream (32.2 ± 3.0 vs. 31.4 ± 2.5 min, p = 0.97); in contrast, K5-IL-17C mice had accelerated occlusion times compared to littermate controls (15.7 ± 2.1 vs. 26.5 ± 3.5 min, p < 0.01) while carotid artery diameters were similar between all mice. Acanthosis, a surrogate measure of inflammation, was increased in both Aldara-treated and K5-IL-17C mice compared to their respective controls. Monocytosis, defined as elevated SDLN and/or splenic CD11b⁺Ly6C^high cells, was significantly increased in both Aldara-treated (SDLN: 3.8-fold, p = 0.02; spleen: 2.0-fold, p < 0.01) and K5-IL-17C (SDLN: 3.4-fold, p = 0.02; spleen: 3.5-fold, p < 0.01) animals compared to controls while neutrophilia, defined as elevated SDLN and/or splenic CD11b⁺Ly6G⁺ cells, was significantly increased in only the chronic K5-IL-17C model (SDLN: 11.6-fold, p = 0.02; spleen: 11.3-fold, p < 0.01). Plasma-derived lipid levels, PT and aPTT times showed no difference between the Aldara-treated mice or the K5-IL-17C mice and their respective controls.

Conclusions

Chronic, but not acute, skin-specific inflammation was associated with faster arterial thrombotic occlusion. Increased numbers of splenic and SDLN monocytes were observed in both acute and chronic skin-specific inflammation, however, increased splenic and SDLN neutrophils were observed only in the chronic skin-specific inflammation model. Understanding the cellular response to skin-specific inflammation may provide insights into the cellular participants mediating the pathophysiology of major adverse cardiovascular events associated with psoriasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0738-z) contains supplementary material, which is available to authorized users.