Emerging Associations Between Neutrophils, Atherosclerosis, and Psoriasis

INFLA score: a novel inflammatory marker for assessing cardiometabolic disease risk in obese individuals

BACKGROUND

The low-grade inflammation score (INFLA-score) is a composite index that assesses chronic inflammatory status using multiple inflammatory markers. However, its correlation with cardiometabolic diseases (CMDs) in obese populations remains unclear.

METHODS

We conducted a prospective cohort study involving 79,160 participants with obesity (BMI ≥ 30 kg/m2) from the UK Biobank. The INFLA-score was calculated based on high-sensitivity C-reactive protein, leukocyte count, platelet count and granulocyte/lymphocyte ratio. We employed Kaplan-Meier survival curves, multivariable Cox regression, restricted cubic splines and accelerated time-to-failure models to analyse the association between the INFLA-score and CMDs risk, including coronary heart disease (CAD), stroke and type 2 diabetes mellitus (T2DM).

RESULTS

Over a median follow-up of 161.41 months, we recorded 14,903 CMDs events, comprising 7184 CAD cases, 1914 strokes and 7924 T2DM cases. Cox regression analysis revealed that each unit increase in the INFLA-score corresponded to a 1.5%, 1.1%, 1.2% and 2.4% increase CMDs risk (HR: 1.015, 95% CI 1.013-1.018), CAD risk (HR: 1.011, 95% CI 1.007-1.015), stroke risk (HR: 1.012, 95% CI 1.004-1.020) and T2DM risk (HR: 1.024, 95% CI 1.020-1.028), respectively. Restricted cubic spline analysis indicated a non-linear relationship between cumulative INFLA-score and CMDs risk (P = 0.044). Subgroup analysis revealed interactions between sex, age, history of lipid-lowering drug use, and INFLA-score regarding CMDs risk. Sensitivity analysis corroborated the main findings.

CONCLUSION

Our findings strongly support the close association between INFLA-score and CMDs risk, particularly notable in women, those aged < 55, and individuals with a history of lipid-lowering drug use. These findings offer new insights into the role of inflammation in obesity-related CMDs, suggesting potential applications for prevention and identification of high-risk populations.

Cardiovascular Considerations and Implications for Treatment in Psoriasis: An Updated Review

Psoriasis, a prevalent chronic inflammatory skin disorder affecting 2-3% of the global population, has transcended its dermatological confines, revealing a profound association with cardiovascular diseases (CVD). This comprehensive review explores the intricate interplay between psoriasis and cardiovascular system, delving into genetic links, immune pathways, and adipose tissue dysfunction beyond conventional CVD risk factors. The pathophysiological connections unveil unique signatures, distinct from other inflammatory skin conditions, in particular psoriasis-specific genetic polymorphisms in IL-23 and TNF-α have consistently been linked to CVD. The review navigates the complex landscape of psoriasis treatments, addressing challenges and future directions in particular relevance to CVDs in psoriasis. Therapeutic interventions, including TNF inhibitors (TNFi), present promise in reducing cardiovascular risks, and methotrexate could constitute a favourable choice. Conversely, the relationship between IL-12/23 inhibitors and cardiovascular risk remains uncertain, while recent evidence indicates that Janus kinase inhibitors may not carry CVD risks. Emerging evidence supports the safety and efficacy of IL-17 and IL-23 inhibitors in patients with CVDs, hinting at evolving therapeutic paradigms. Lifestyle modifications, statins, and emerging therapies offer preventive strategies. Dedicated screening guidelines for CVD risk assessment in psoriasis are however lacking. Further, the impact of different disease phenotypes and treatment hierarchies in cardiovascular outcomes remains elusive, demanding ongoing research at the intersection of dermatology, rheumatology, and cardiology. In conclusion, unraveling the intricate connections between psoriasis and CVD provides a foundation for a holistic approach to patient care. Collaboration between specialties, advancements in screening methodologies, and a nuanced understanding of treatment impacts are essential for comprehensive cardiovascular risk management in individuals with psoriasis.

Neutrophil hitchhiking: Riding the drug delivery wave to treat diseases

Neutrophils are a crucial component of the innate immune system and play a pivotal role in various physiological processes. From a physical perspective, hitchhiking is considered a phenomenon of efficient transportation. The combination of neutrophils and hitchhikers has given rise to effective delivery systems both in vivo and in vitro, thus neutrophils hitchhiking become a novel approach to disease treatment. This article provides an overview of the innovative and feasible application of neutrophils as drug carriers. It explores the mechanisms underlying neutrophil function, elucidates the mechanism of drug delivery mediated by neutrophil-hitchhiking, and discusses the potential applications of this strategy in the treatment of cancer, immune diseases, inflammatory diseases, and other medical conditions.

Low-density granulocytes in systemic autoimmunity and autoinflammation

A body of evidence has re-energized the interest on the role neutrophils in inflammatory and autoimmune conditions. For decades, neutrophils have been considered a homogenous population. Nevertheless, accumulating evidence suggests that neutrophils are more versatile and heterogeneous than initially considered. The notion of neutrophil heterogeneity has been supported by the identification of low-density granulocytes (LDGs) in systemic lupus erythematosus (SLE) and other systemic autoimmune and autoinflammatory conditions. Transcriptomic, epigenetic, proteomic, and functional analyses support that LDGs are a distinct subset of proinflammatory neutrophils implicated in the pathogenesis of SLE and other autoimmune diseases. Importantly, it remains incompletely characterized whether LDGs detected in other inflammatory/autoimmune conditions display the same phenotype that those present in SLE. A shared feature of LDGs across diseases is their association with vascular damage, an important contributor to morbidity and mortality in chronic inflammatory conditions. Additionally, the lack of specific markers to identify LDGs in circulation or in tissue, makes it a challenge to elucidate their role in the pathogenesis of inflammatory and autoimmune conditions. In this review, we aim to examine the evidence on the biology and the putative pathogenic role of LDGs in systemic autoimmune diseases.

Immunity: Psoriasis comorbid with atherosclerosis

Psoriasis is an immune-mediated, persistent inflammatory disease with a genetic predisposition, and the involvement of multiple organs in psoriasis remains indicative of systemic disease. Atherosclerosis (AS) is a common complication of patients with severe or prolonged psoriasis. The specific pathogenesis of psoriasis is still unclear. Current studies suggest that psoriasis is a polygenic genetic disease with the interaction of multiple factors such as heredity and environment. Keratinocytes are proliferated through immune-mediated inflammatory pathway, which leads to cell activation, infiltration of dermis cells and release of inflammatory factors. Activation of inflammatory cells and pro-inflammatory factors play an important role in the progression of psoriasis and atherosclerosis. Studies have found that there is a close relationship between psoriasis and atherosclerosis, and systemic inflammation may be the common feature of psoriasis and AS. This paper attempts to explore the possibility of the relationship between psoriasis and atherosclerotic comorbidities from the aspects of potential epidemiology and immune mechanism, in order to provide some reference for the subsequent scientific research.

There is urgent need to treat atherosclerotic cardiovascular disease risk earlier, more intensively, and with greater precision: A review of current practice and recommendations for improved effectiveness

Atherosclerotic cardiovascular disease (ASCVD) is epidemic throughout the world and is etiologic for such acute cardiovascular events as myocardial infarction, ischemic stroke, unstable angina, and death. ASCVD also impacts risk for dementia, chronic kidney disease peripheral arterial disease and mobility, impaired sexual response, and a host of other visceral impairments that adversely impact the quality and rate of progression of aging. The relationship between low-density lipoprotein cholesterol (LDL-C) and risk for ASCVD is one of the most highly established and investigated issues in the entirety of modern medicine. Elevated LDL-C is a necessary condition for atherogenesis induction. Basic scientific investigation, prospective longitudinal cohorts, and randomized clinical trials have all validated this association. Yet despite the enormous number of clinical trials which support the need for reducing the burden of atherogenic lipoprotein in blood, the percentage of high and very high-risk patients who achieve risk stratified LDL-C target reductions is low and has remained low for the last thirty years. Atherosclerosis is a preventable disease. As clinicians, the time has come for us to take primordial and primary prevention more serously. Despite a plethora of therapeutic approaches, the large majority of patients at risk for ASCVD are poorly or inadequately treated, leaving them vulnerable to disease progression, acute cardiovascular events, and poor aging due to loss of function in multiple visceral organs. Herein we discuss the need to greatly intensify efforts to reduce risk, decrease disease burden, and provide more comprehensive and earlier risk assessment to optimally prevent ASCVD and its complications. Evidence is presented to support that treatment should aim for far lower goals in cholesterol management, should take into account many more factors than commonly employed today and should begin significantly earlier in life.

Role of Lipid-Lowering Therapy in Peripheral Artery Disease

Atherosclerosis is a multifactorial, lipoprotein-driven condition that leads to plaque formation within the arterial tree, leading to subsequent arterial stenosis and thrombosis that accounts for a large burden of cardiovascular morbidity and mortality globally. Atherosclerosis of the lower extremities is called peripheral artery disease and is a major cause of loss in mobility, amputation, and critical limb ischemia. Peripheral artery disease is a common condition with a gamut of clinical manifestations that affects an estimated 10 million people in the United States of America and 200 million people worldwide. The role of apolipoprotein B-containing lipoproteins, such as LDL and remnant lipoproteins in the development and progression of atherosclerosis, is well-established. The focus of this paper is to review existing data on lipid-lowering therapies in lower extremity atherosclerotic peripheral artery disease.

Antigen-Presenting Cell-Like Neutrophils Foster T Cell Response in Hyperlipidemic Patients and Atherosclerotic Mice

Neutrophils constitute abundant cellular components in atherosclerotic plaques. Most of the current studies are focused on the roles of granular proteins released by neutrophils in atherosclerosis. Here, we revealed a unique subset of neutrophils which exhibit the characteristics of antigen-presenting cell (APC) (which were called APC-like neutrophils afterwards) in atherosclerosis. The roles of APC-like neutrophils and relevant mechanisms were investigated in hyperlipidemic patients and atherosclerotic mice. Higher percentages of neutrophils and APC-like neutrophils were found in peripheral blood of hyperlipidemic patients than that of healthy donors. Meanwhile, we also identified higher infiltration of neutrophils and APC-like neutrophils in atherosclerotic mice. Ox-LDL induced Phorbol-12-myristate-13-acetate (PMA)-activated neutrophils to acquire the APC-like phenotype. Importantly, upon over-expression of APC-like markers, neutrophils acquired APC functions to promote the proliferation and interferon-γ production of CD3⁺ T cells via HLA-DR/CD80/CD86. In accordance with what found in vitro, positive correlation between neutrophils and CD3⁺ T cells was observed in hyperlipidemic patients. In conclusion, our work identifies a proinflammatory neutrophil subset in both hyperlipidemic patients and atherosclerotic mice. This unique phenotype of neutrophils could activate the adaptive immune response to promote atherosclerosis progression. Thus, this neutrophil subset may be a new target for immunotherapy of atherosclerosis.

Effect of Secukinumab on Traditional Cardiovascular Risk Factors and Inflammatory Biomarkers: Post Hoc Analyses of Pooled Data Across Three Indications

Background

Psoriasis, psoriatic arthritis (PsA), and axial spondyloarthritis (axSpA) are chronic immune-mediated inflammatory diseases (IMIDs) associated with cardiovascular (CV) disease. High-sensitivity C-reactive protein (hsCRP) and, more recently, the neutrophil–lymphocyte ratio (NLR) are important inflammatory biomarkers predictive of CV disease and CV disease-associated mortality. Here, we report the effect of interleukin (IL)-17A inhibition with secukinumab on CV risk parameters in patients with psoriasis, PsA, and axSpA over 1 year of treatment.

Methods

This was a post hoc analysis of pooled data from phase 3/4 secukinumab studies in psoriasis, PsA, and axSpA. CV-related exclusion criteria included uncontrolled hypertension and congestive heart failure. Traditional risk factors assessed were body mass index (BMI) > 25, high fasting glucose and blood pressure (systolic and diastolic), and high cholesterol (low-density lipoproteins [LDL], total cholesterol/HDL ratio, and triglycerides). Inflammatory CV risk parameters assessed were hsCRP and NLR. Statistical analysis was descriptive. Subgroup analyses were performed in high-risk patients defined as having baseline hsCRP > 4 mg/L (patients with psoriasis) and > 10 mg/L (patients with PsA/axSpA).

Results

In total, 9197 patients from 19 clinical trials (8 in psoriasis, n = 4742; 5 in PsA, n = 2475; 6 in axSpA, n = 1980) were included. All traditional CV risk parameters remained stable in secukinumab-treated patients through 1 year. Secukinumab rapidly reduced both hsCRP and the NLR compared with placebo at week 12 (psoriasis) or week 16 (PsA/axSpA) in the overall population and in high-risk patients (all P < 0.01). This reduction was maintained for at least 1 year of secukinumab therapy in all indications.

Conclusions

Secukinumab led to a rapid and sustained reduction in hsCRP and the NLR in patients with IMIDs with a high systemic inflammatory burden. Traditional CV risk factors remained stable for at least 1 year in patients with psoriasis, PsA, and axSpA. Taken together, secukinumab had a favorable effect on systemic inflammation without impact on traditional CV risk factors.

Trials Registration

ClinicalTrials.gov, NCT01365455, NCT01358578, NCT01406938, NCT01555125, NCT01636687, NCT02752776, NCT02074982, NCT02826603, NCT01752634, NCT01989468, NCT02294227, NCT02404350, NCT02745080, NCT01863732, NCT01649375, NCT02008916, NCT02159053, NCT02896127, NCT02696031.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-022-00434-z.

Inflammatory Cells in Atherosclerosis

Atherosclerosis is a chronic progressive disease that involves damage to the intima, inflammatory cell recruitment and the accumulation of lipids followed by calcification and plaque rupture. Inflammation is considered a key mediator of many events during the development and progression of the disease. Various types of inflammatory cells are reported to be involved in atherosclerosis. In the present paper, we discuss the involved inflammatory cells, their characteristic and functional significance in the development and progression of atherosclerosis. The detailed understanding of the role of all these cells in disease progression at different stages sheds more light on the subject and provides valuable insights as to where and when therapy should be targeted.

Neutrophil Pathways of Inflammation Characterize the Blood Transcriptomic Signature of Patients with Psoriasis and Cardiovascular Disease

BACKGROUND

Patients with psoriasis have an increased risk of atherosclerotic cardiovascular disease (CVD). The molecular mechanisms behind this connection are not fully understood, but the involvement of neutrophils have drawn attention as a shared inflammatory factor.

METHODS

RNA sequencing using the Illumina platform was performed on blood from 38 patients with moderate to severe psoriasis; approximately half had prior CVD. The neutrophil to lymphocyte ratio (NLR) was obtained from blood samples. Subclinical atherosclerosis was assessed by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography and ultrasound imaging. Transcriptomic analysis for differential expression and functional enrichment were performed, followed by correlation analyses of differentially expressed genes (DEGs), NLR and subclinical measurers of CVD.

RESULTS

291 genes were differentially expressed between patients with psoriasis with and without CVD. These included 208 upregulated and 83 downregulated DEGs. Neutrophil degranulation was identified as the most significant process related to the upregulated DEGs. Genes for the neutrophil-associated markers MPO, MMP9, LCN2, CEACAM1, CEACAM6 and CEACAM8 were identified as being of special interest and their mRNA levels correlated with NLR, high-sensitive C-reactive protein and markers of subclinical CVD.

CONCLUSIONS

Patients with psoriasis and CVD had an increased expression of genes related to neutrophil degranulation in their blood transcriptome compared with patients with psoriasis without CVD. NLR may be a potential biomarker of subclinical CVD in psoriasis.

The lipid paradox in neuroprogressive disorders: Causes and consequences

Chronic systemic inflammation is associated with an increased risk of cardiovascular disease in an environment of low low-density lipoprotein (LDL) and low total cholesterol and with the pathophysiology of neuroprogressive disorders. The causes and consequences of this lipid paradox are explored. Circulating activated neutrophils can release inflammatory molecules such as myeloperoxidase and the pro-inflammatory cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha. Since activated neutrophils are associated with atherosclerosis and cardiovascular disease and with major depressive disorder, bipolar disorder and schizophrenia, it seems reasonable to hypothesise that the inflammatory molecules released by them may act as mediators of the link between systemic inflammation and the development of atherosclerosis in neuroprogressive disorders. This hypothesis is tested by considering the association at a molecular level of systemic inflammation with increased LDL oxidation; increased small dense LDL levels; increased lipoprotein (a) concentration; secretory phospholipase A₂ activation; cytosolic phospholipase A₂ activation; increased platelet activation; decreased apolipoprotein A1 levels and function; decreased paroxonase-1 activity; hyperhomocysteinaemia; and metabolic endotoxaemia. These molecular mechanisms suggest potential therapeutic targets.

[Obesity - A Risk Factor for Psoriasis and COVID-19]

Obesity is a major health problem whose well-known association with psoriasis has been amply described. The importance of obesity as a risk factor for poor prognosis in the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 infection has recently been demonstrated. This review examines a possible relationship between obesity, psoriasis, and COVID-19, analyzing the pathophysiological links and their practical implications. On the one hand, a higher body mass index increases the risk of psoriasis and is also a factor in metabolic syndrome, which is common in patients with psoriasis and has been implicated in reducing the effectiveness of psoriasis treatments. On the other hand, obesity is a risk factor for severe COVID-19 and mortality. Obesity also promotes a proinflammatory state in the lung, where it compromises respiratory mechanics.

Obesity - A Risk Factor for Psoriasis and COVID-19

Obesity is a major health problem whose well-known association with psoriasis has been amply described. The importance of obesity as a risk factor for poor prognosis in the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 infection has recently been demonstrated. This review examines a possible relationship between obesity, psoriasis, and COVID-19, analyzing the pathophysiological links and their practical implications. On the one hand, a higher body mass index increases the risk of psoriasis and is also a factor in metabolic syndrome, which is common in patients with psoriasis and has been implicated in reducing the effectiveness of psoriasis treatments. On the other hand, obesity is a risk factor for severe COVID-19 and mortality. Obesity also promotes a proinflammatory state in the lung, where it compromises respiratory mechanics.

Improved mouse models and advanced genetic and genomic technologies for the study of neutrophils

Mice have been excellent surrogates for studying neutrophil biology and, furthermore, murine models of human disease have provided fundamental insights into the roles of human neutrophils in innate immunity. The emergence of novel humanized mice and high-diversity mouse populations offers the research community innovative and powerful platforms for better understanding, respectively, the mechanisms by which human neutrophils drive pathogenicity, and how genetic differences underpin the variation in neutrophil biology observed among humans. Here, we review key examples of these new resources. Additionally, we provide an overview of advanced genetic engineering tools available to further improve such murine model systems, of sophisticated neutrophil-profiling technologies, and of multifunctional nanoparticle (NP)-based neutrophil-targeting strategies.

Effect of combined colchicine-corticosteroid treatment on neutrophil/lymphocyte ratio: a predictive marker in Behçet disease activity

BACKGROUND AND AIMS

Behçet's disease (BD) is an auto-immune vasculitis, characterized by episodic inflammation of multiple organs. The neutrophil to lymphocyte ratio (NLR) is used as a marker of inflammation in several diseases nowadays. While nitric oxide (NO) seem to be involved in BD pathogenicity. Our study aims to investigate the NLR as an inflammatory marker of BD activity as well as to evaluate the relationship between the NO production and NLR in Algerian BD patients with different clinical manifestations before and under colchicine + corticosteroid treatment.

METHODS

For this purpose, we evaluated the NLR as the ratio of neutrophil count to lymphocyte count in naïve and treated active BD patients with different clinical manifestations and in inactive ones. Furthermore, we assessed NO production by the Griess' method in the same patients. Additionally, we evaluated in vivo interferon-γ (IFN-γ) and interleukin-4 (IL-4) levels using ELISA.

RESULTS AND DISCUSSION

Our results indicate that the NLR and nitrite levels were higher in naïve active BD patients. Interestingly, this high ratio and NO production differed according to the clinical manifestations and was associated with an increased risk of mucocutaneous and vascular involvement. Importantly, in treated BD patients NLR was higher in active patients especially in those with mucocutaneous involvement while increased nitrites levels were regardless of the clinical manifestations studied. Both NLR and NO production decreased in these treated active patients. In addition, IL-4 production differed according to the clinical manifestations studied contrary to the IFN-γ production.

CONCLUSION

Collectively our results suggest that the NLR is a potential marker of BD activity in Algerian patients, predicting the disease severity. Moreover, the positive relationship between the NLR and NO production is related to an increased risk of mucocutaneous lesions and vascular involvement. Thus, the application of these two accessible tools could be benefit for the clinical prognosis and treatment of BD.

Pathogenesis of Chronic Plaque Psoriasis and Its Intersection With Cardio-Metabolic Comorbidities

Psoriasis is a chronic, systemic immune-mediated disease characterized by development of erythematous, indurated, scaly, pruritic plaques on the skin. Psoriasis is frequently associated to comorbidities, including psoriatic arthritis, cardiovascular diseases, diabetes mellitus, obesity, non-alcoholic fatty liver disease, and inflammatory bowel diseases. In this review, we discuss the pathophysiological relationship between psoriasis and cardio-metabolic comorbidities and the importance of therapeutic strategies to reduce systemic inflammation in patients with moderate-to-severe psoriasis. Pathogenesis of psoriasis and its comorbidities share both genetic predisposition and inflammatory pathways, which include the TNFα and the IL-23/IL-17 pathways. These pathways are selectively addressed by biological treatments, which have substantially changed the outcomes of psoriasis therapy and affect positively comorbidities including reducing cardiovascular risk, allowing a more comprehensive approach to the patient.

IL-17A in Psoriasis and Beyond: Cardiovascular and Metabolic Implications

Interleukin 17A (IL-17A) is one of the currently known six members of the IL-17 cytokine family and is implicated in immune responses to infectious pathogens and in the pathogenesis of inflammatory autoimmune diseases like psoriasis. Psoriatic skin is characterized by high expression of IL-17A and IL-17F, which act on immune and non-immune cell types and strongly contribute to tissue inflammation. In psoriatic lesions, IL-17A, IL-17E, and IL-17F are involved in neutrophil accumulation, followed by the formation of epidermal micro abscesses. IL-17A together with other Th17 cytokines also upregulates the production of several chemokines that are implicated in psoriasis pathogenesis. IL17A-targeting antibodies show an impressive clinical efficacy in patients with psoriasis. Studies have reported an improvement of at least 75% as measured by the psoriasis area and severity index (PASI) in >80% of patients treated with anti-IL-17A therapy. Psoriasis skin manifestations, cardiovascular as well as metabolic disease in psoriasis appear to share pathogenic mechanisms evolving around IL-17A and its proinflammatory role. Thus, anti-IL-17A therapy not only improves skin manifestations of psoriasis, but also cardiovascular inflammation as well as metabolic factors and different domains of psoriatic arthritis (PsA) including peripheral arthritis, enthesitis, dactylitis, and axial involvement. This review summarizes the biological role of IL-17A, before reviewing currently available data on its role in the physiology and pathophysiology of the skin, as well as the cardiovascular and the metabolic system. In conclusion, clinical recommendations for patients with moderate to severe psoriasis based on the current available data are given.

Neutrophils in Psoriasis

Neutrophils are the most abundant innate immune cells. The pathogenic roles of neutrophils are related to chronic inflammation and autoimmune diseases. Psoriasis is a chronic systemic inflammatory disease affecting ~2–3% of the world population. The abundant presence of neutrophils in the psoriatic skin lesions serves as a typical histopathologic hallmark of psoriasis. Recent reports indicated that oxidative stress, granular components, and neutrophil extracellular traps from psoriatic neutrophils are related to the initial and maintenance phases of psoriasis. This review provides an overview on the recent (up to 2019) advances in understanding the role of neutrophils in the pathophysiology of psoriasis, including the effects of respiratory burst, degranulation, and neutrophil extracellular trap formation on psoriatic immunity and the clinical relationships.

Transient receptor potential ankyrin 1 (TRPA1) positively regulates imiquimod-induced, psoriasiform dermal inflammation in mice

Transient receptor potential ankyrin 1 (TRPA1), a membrane protein ion channel, is known to mediate itch and pain in skin. The function of TRPA1, however, in psoriasiform dermatitis (PsD) is uncertain. Herein, we found that expression of TRPA1 is highly up-regulated in human psoriatic lesional skin. To study the role of TRPA1 in PsD, we assessed Psoriasis Severity Index (PSI) scores, transepidermal water loss (TEWL), skin thickness and pathology, and examined dermal inflammatory infiltrates, Th17-related genes and itch-related genes in c57BL/6 as wild-type (WT) and TRPA1 gene knockout (KO) mice following daily application of topical IMQ cream for 5 days. Compared with WT mice, clinical scores, skin thickness change and TEWL scores were similar on day 3, but were significantly decreased on day 5 in IMQ-treated TRPA1 KO mice (vs WT mice), suggesting reduced inflammation and skin barrier defects. Additionally, the relative area of epidermal Munro's microabscesses and mRNA levels of neutrophil inducible chemokines (S100A8, S100A9 and CXCL1) were decreased in the treated skin of TRPA1 KO mice, suggesting that neutrophil recruitment was impaired in the KO mice. Furthermore, mast cells, CD31⁺ blood vascular cells, CD45⁺ leukocytes and CD3⁺ T cells were all reduced in the treated skin of TRPA1 KO mice. Lastly, mRNA expression levels of IL-1β, IL-6, IL-23, IL-17A, IL-17F and IL-22 were decreased in TRPA1 KO mice. In summary, these results suggest a key role for TRPA1 in psoriasiform inflammation and raising its potential as a target for therapeutic intervention.

2D Visualization of the Psoriasis Transcriptome Fails to Support the Existence of Dual-Secreting IL-17A/IL-22 Th17 T Cells

The present paradigm of psoriasis pathogenesis revolves around the IL-23/IL-17A axis. Dual-secreting Th17 T cells presumably are the predominant sources of the psoriasis phenotype-driving cytokines, IL-17A and IL-22. We thus conducted a meta-analysis of independently acquired RNA-seq psoriasis datasets to explore the relationship between the expression of IL17A and IL22. This analysis failed to support the existence of dual secreting IL-17A/IL-22 Th17 cells as a major source of these cytokines. However, variable relationships amongst the expression of psoriasis susceptibility genes and of IL17A, IL22, and IL23A were identified. Additionally, to shed light on gene expression relationships in psoriasis, we applied a machine learning nonlinear dimensionality reduction strategy (t-SNE) to display the entire psoriasis transcriptome as a 2-dimensonal image. This analysis revealed a variety of gene clusters, relevant to psoriasis pathophysiology but failed to support a relationship between IL17A and IL22. These results support existing theories on alternative sources of IL-17A and IL-22 in psoriasis such as a Th22 cells and non-T cell populations.

Update on Neutrophil Function in Severe Inflammation

Neutrophils are main players in the effector phase of the host defense against micro-organisms and have a major role in the innate immune response. Neutrophils show phenotypic heterogeneity and functional flexibility, which highlight their importance in regulation of immune function. However, neutrophils can play a dual role and besides their antimicrobial function, deregulation of neutrophils and their hyperactivity can lead to tissue damage in severe inflammation or trauma. Neutrophils also have an important role in the modulation of the immune system in response to severe injury and trauma. In this review we will provide an overview of the current understanding of neutrophil subpopulations and their function during and post-infection and discuss the possible mechanisms of immune modulation by neutrophils in severe inflammation.

MRI of atherosclerosis and fatty liver disease in cholesterol fed rabbits

Background

The globally rising obesity epidemic is associated with a broad spectrum of diseases including atherosclerosis and non-alcoholic fatty liver (NAFL) disease. In the past, research focused on the vasculature or liver, but chronic systemic effects and inter-organ communication may promote the development of NAFL. Here, we investigated the impact of confined vascular endothelial injury, which produces highly inflamed aortic plaques that are susceptible to rupture, on the progression of NAFL in cholesterol fed rabbits.

Methods

Aortic atherosclerotic inflammation (plaque Gd-enhancement), plaque size (vessel wall area), and composition, were measured with in vivo magnetic resonance imaging (MRI) in rabbits fed normal chow or a 1% cholesterol-enriched atherogenic diet. Liver fat was quantified with magnetic resonance spectroscopy (MRS) over 3 months. Blood biomarkers were monitored in the animals, with follow-up by histology.

Results

Cholesterol-fed rabbits with and without injury developed hypercholesterolemia, NAFL, and atherosclerotic plaques in the aorta. Compared with rabbits fed cholesterol diet alone, rabbits with injury and cholesterol diets exhibited larger, and more highly inflamed plaques by MRI (P < 0.05) and aggravated liver steatosis by MRS (P < 0.05). Moreover, after sacrifice, damaged (ballooning) hepatocytes and extensive liver fibrosis were observed by histology. Elevated plasma gamma-glutamyl transferase (GGT; P = 0.014) and the ratio of liver enzymes aspartate and alanine aminotransferases (AST/ALT; P = 0.033) indicated the progression of steatosis to non-alcoholic steatohepatitis (NASH).

Conclusions

Localized regions of highly inflamed aortic atherosclerotic plaques in cholesterol-fed rabbits may contribute to progression of fatty liver disease to NASH with fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1587-3) contains supplementary material, which is available to authorized users.

T Cell Hierarchy in the Pathogenesis of Psoriasis and Associated Cardiovascular Comorbidities

The key role of T cells in the pathogenesis of cutaneous psoriasis has been well described in the last decade and the knowledge of the relative role of the different subsets of T cells in psoriasis pathogenesis has considerably evolved. Now, it is clear that IL-17A-producing T cells, including Th17/Tc17, have a central role in the pathogenesis of cutaneous psoriasis and therapies blocking the IL-17A pathway show high clinical efficacy. By contrast, the contribution of IFNγ-producing T cells has progressively become less clear because of the lack of efficacy of anti-IFNγ antibodies in clinical studies. In parallel, the role of CD8⁺ T cells specific for self-antigens has been revived and increasing evidence now indicates that in psoriatic skin the majority CD8⁺ T cells are present in the form of epidermal tissue-resident memory T cells. In the last years it also emerged the possibility of a contribution of T cell recirculation in the pathogenesis of psoriasis and its systemic manifestations. The aim of this review is to define a hierarchy for the different subsets of T cells in the T cell-mediated inflammatory cascade in psoriatic skin. This analysis will possibly help to distinguish the subsets that initiate the disease, those involved in the establishment of the self-sustaining amplification loop that leads to the cutaneous clinical manifestations and finally the subsets that act as downstream players in established lesions. Specific T cell subpopulations finally will be considered for their possible role in propagating inflammation at distant sites and for representing a link with systemic inflammation and cardiovascular comorbidities.

Potential Immunological Links Between Psoriasis and Cardiovascular Disease

Preclinical and clinical research provide strong evidence that chronic, systemic inflammation plays a key role in development and progression of atherosclerosis. Indeed, chronic inflammatory diseases, such as psoriasis, are associated with accelerated atherosclerosis and increased risk of cardiovascular events. Contemporary research has demonstrated plausible mechanistic links between immune cell dysfunction and cardiometabolic disease in psoriasis. In this review, we describe the role of potential common immunological mechanisms underlying both psoriasis and atherogenesis. We primarily discuss innate and adaptive immune cell subsets and their contributions to psoriatic disease and cardiovascular morbidity. Emerging efforts should focus on understanding the interplay among immune cells, adipose tissue, and various biomarkers of immune dysfunction to provide direction for future targeted therapy.