Psoriatic cutaneous inflammation promotes human monocyte differentiation into active osteoclasts, facilitating bone damage

Exploring the Link Between Psoriasis and Adipose Tissue: One Amplifies the Other

Psoriasis and obesity, while distinct, are inter-related inflammatory conditions. Adipose tissue (AT)-derived mediators could be pathogenically active in triggering and/or amplifying psoriatic skin inflammation and, vice versa, skin inflammation could drive increased adiposity that triggers the development of several chronic conditions. Gaining insight into their intricate relationship could be essential for effective management and treatment. The aim of this study was to determine (i) the pathogenic role of psoriasis-signature cytokines in contributing to AT metabolism and (ii) the role of AT-derived mediators in triggering and/or amplifying skin inflammation. For this reason, firstly, whole AT was treated with IL-17 and TNF-α, alone or in combination, to investigate their effects on the expression and production of adipokines and inflammatory factors. IL-17 and TNF-α were able to induce an additive or synergistic effect on AT-derived mediators. In order to assess the effects on the skin of inflamed AT by psoriasis-signature cytokines, ex vivo skin organ culture was performed and an increase in several inflammatory mediators was observed. These findings confirm that psoriasis and obesity amplify each other's inflammatory processes and understanding this mutual exacerbation could lead to more effective therapeutic strategies that address both skin inflammation and AT metabolism.

Metabolic Syndrome and Psoriasis: Pivotal Roles of Chronic Inflammation and Gut Microbiota

In recent years, the incidence of metabolic syndrome (MS) has increased due to lifestyle-related factors in developed countries. MS represents a group of conditions that increase the risk of diabetes, cardiovascular diseases, and other severe health problems. Low-grade chronic inflammation is now considered one of the key aspects of MS and could be defined as a new cardiovascular risk factor. Indeed, an increase in visceral adipose tissue, typical of obesity, contributes to the development of an inflammatory state, which, in turn, induces the production of several proinflammatory cytokines responsible for insulin resistance. Psoriasis is a chronic relapsing inflammatory skin disease and is characterized by the increased release of pro-inflammatory cytokines, which can contribute to different pathological conditions within the spectrum of MS. A link between metabolic disorders and Psoriasis has emerged from evidence indicating that weight loss obtained through healthy diets and exercise was able to improve the clinical course and therapeutic response of Psoriasis in patients with obesity or overweight patients and even prevent its occurrence. A key factor in this balance is the gut microbiota; it is an extremely dynamic system, and this makes its manipulation through diet possible via probiotic, prebiotic, and symbiotic compounds. Given this, the gut microbiota represents an additional therapeutic target that can improve metabolism in different clinical conditions.

The Fracture Risk of Elderly Patients With Atopic Dermatitis

Background: A higher fracture risk has been reported previously in patients with atopic Dermatitis (AD). The bone mineral density (BMD) was not accounted for in these studies. Objective: To investigate the fracture risk in AD patients after adjustment for factors including BMD. Methods: We retrospectively analyzed AD patients (≥45 years) who underwent BMD examination at our hospital from July 2010 to February 2023. Individuals who received BMD examinations during a health checkup were identified as the controls. We documented their clinical characteristics, BMD, 10-year risk for a major fracture based on FRAX (Fracture Risk Assessment Tool), and development of osteoporotic fractures. Patients were followed until development of new onset fracture or the end of the study period. A cross-sectional comparison of BMD between AD patients and controls at baseline was performed using the Mann-Whitney U test after propensity score matching (PSM). Their fracture risks were compared using the multivariate Cox regression model. BMD and fracture risk were also compared between AD patients who received systemic therapy and those who did not. Results: A total of 50 AD patients and 386 controls were enrolled. The median age was older in AD patients when compared with controls (70 years vs 60 years). Their BMD at all sites was similar after PSM. After a median follow-up of 1.7-2.0 years, 13 osteoporotic fractures were identified. In the multivariate Cox regression analysis, AD was not associated with new onset fractures of all sites (adjusted hazard ratio [aHR] 2.55, 95% confidence interval [CI] 0.72-9.01) but was significantly associated with new onset vertebral fractures (aHR 6.80, 95% CI 1.77-26.17). The BMD and incidence of fractures were similar between AD who received systemic therapy and those who did not. Conclusions: Elderly AD patients had similar BMD but a higher short-term risk for vertebral fractures when compared with the controls.

The Role of Alarmins in the Pathogenesis of Rheumatoid Arthritis, Osteoarthritis, and Psoriasis

Alarmins are immune-activating factors released after cellular injury or death. By secreting alarmins, cells can interact with immune cells and induce a variety of inflammatory responses. The broad family of alarmins involves several members, such as high-mobility group box 1, S100 proteins, interleukin-33, and heat shock proteins, among others. Studies have found that the concentrations and expression profiles of alarmins are altered in immune-mediated diseases. Furthermore, they are involved in the pathogenesis of inflammatory conditions. The aim of this narrative review is to present the current evidence on the role of alarmins in rheumatoid arthritis, osteoarthritis, and psoriasis. We discuss their potential involvement in mechanisms underlying the progression of these diseases and whether they could become therapeutic targets. Moreover, we summarize the impact of pharmacological agents used in the treatment of these diseases on the expression of alarmins.

Interleukins and Psoriasis

Psoriasis is an immune-mediated chronic inflammatory skin disease that affects 2% to 3% of the world's population. It is widely assumed that immune cells and cytokines acting together play a crucial part in the pathophysiology of psoriasis by promoting the excessive proliferation of skin keratinocytes and inflammatory infiltration. Interleukins (ILs), as a critical component of cytokines, have been closely associated with the pathogenesis and progression of psoriasis. This review summarizes the current contribution of ILs to psoriasis and describes the role each IL performs in psoriasis. Furthermore, the paper presents the therapeutic effects and application prospects of biologics developed for ILs in clinical treatment and experiments. The study aims to further the research on ILs in the treatment of psoriasis.

In vitro osteoclastogenesis in autoimmune diseases - Strengths and pitfalls of a tool for studying pathological bone resorption and other disease characteristics

Osteoclasts play a critical role in bone pathology frequently associated with autoimmune diseases. Studying the etiopathogenesis of these diseases and their clinical manifestations can involve in vitro osteoclastogenesis, an experimental technique that utilizes osteoclast precursors that are relatively easily accessible from peripheral blood or synovial fluid. However, the increasing number of methodical options to study osteoclastogenesis in vitro poses challenges in translating findings to clinical research and practice. This review compares and critically evaluates previous research work based on in vitro differentiation of human osteoclast precursors originating from patients, which aimed to explain autoimmune pathology in rheumatic and enteropathic diseases. The discussion focuses primarily on methodical differences between the studies, including the origin of osteoclast precursors, culture conditions, and methods for identifying osteoclasts and assessing their activity. Additionally, the review examines the clinical significance of the three most commonly used in vitro approaches: induced osteoclastogenesis, spontaneous osteoclastogenesis, and cell co-culture. By analyzing and integrating the gathered information, this review proposes general connections between different studies, even in cases where their results are seemingly contradictory. The derived conclusions and future directions aim to enhance our understanding of a potential and limitations of in vitro osteoclastogenesis and provide a foundation for discussing novel methods (such as osteoclastogenesis dynamic) and standardized approaches (such as spontaneous osteoclastogenesis) for future use in autoimmune disease research.

Fracture risks and their mechanisms in atopic dermatitis, focusing on receptor activator of nuclear factor kappa-B ligand

Recent multiple studies have shown that the long-term consequences of atopic dermatitis (AD) include an increased risk of osteoporosis and fracture, especially an increase in hip, pelvic, spinal and wrist fractures. AD is very common worldwide, and some kinds of fractures, such as hip fractures, are associated with increased mortality, which has a substantial socioeconomic impact; however, the precise mechanisms for this remain unclear. Receptor activator of nuclear factor kappa-Β (RANK) ligand (RANKL) and osteoprotegerin (OPG) are members of the tumour necrosis factor ligand and receptor family, members of which also are known as bone biomarkers. Alterations in the RANKL/RANK/OPG system and the balance among these factors (represented by the RANKL/OPG ratio) are central to the pathogenesis of bone loss from osteoporosis, and it is postulated that there is a potential association between the serum levels of RANKL and OPG, and bone density or fracture. Recently, our research group demonstrated that the serum RANKL/OPG ratio positively correlated with AD severity and suggests fracture risk in older women with AD. This review summarizes and discusses the risk and mechanisms of osteoporotic fracture in AD. RANKL may be involved in the pathogenesis of AD, regarding not only bone abnormality but also inflammation. Although further investigation will be needed to verify the hypotheses, recent findings may provide new insights into the pathogenesis of AD and therapeutic targets.

Bone Involvement in Rheumatoid Arthritis and Spondyloartritis: An Updated Review

Several rheumatologic diseases are primarily distinguished by their involvement of bone tissue, which not only serves as a mere target of the condition but often plays a pivotal role in its pathogenesis. This scenario is particularly prominent in chronic inflammatory arthritis such as rheumatoid arthritis (RA) and spondyloarthritis (SpA). Given the immunological and systemic nature of these diseases, in this review, we report an overview of the pathogenic mechanisms underlying specific bone involvement, focusing on the complex interactions that occur between bone tissue's own cells and the molecular and cellular actors of the immune system, a recent and fascinating field of interest defined as osteoimmunology. Specifically, we comprehensively elaborate on the distinct pathogenic mechanisms of bone erosion seen in both rheumatoid arthritis and spondyloarthritis, as well as the characteristic process of aberrant bone formation observed in spondyloarthritis. Lastly, chronic inflammatory arthritis leads to systemic bone involvement, resulting in systemic bone loss and consequent osteoporosis, along with increased skeletal fragility.

Strontium chloride improves bone mass by affecting the gut microbiota in young male rats

Introduction

Bone mass accumulated in early adulthood is an important determinant of bone mass throughout the lifespan, and inadequate bone deposition may lead to associated skeletal diseases. Recent studies suggest that gut bacteria may be potential factors in boosting bone mass. Strontium (Sr) as a key bioactive element has been shown to improve bone quality, but the precise way that maintains the equilibrium of the gut microbiome and bone health is still not well understood.

Methods

We explored the capacity of SrCl2 solutions of varying concentrations (0, 100, 200 and 400 mg/kg BW) on bone quality in 7-week-old male Wistar rats and attempted to elucidate the mechanism through gut microbes.

Results

The results showed that in a Wistar rat model under normal growth conditions, serum Ca levels increased after Sr-treatment and showed a dose-dependent increase with Sr concentration. Three-point mechanics and Micro-CT results showed that Sr exposure enhanced bone biomechanical properties and improved bone microarchitecture. In addition, the osteoblast gene markers BMP, BGP, RUNX2, OPG and ALP mRNA levels were significantly increased to varying degrees after Sr treatment, and the osteoclast markers RANKL and TRAP were accompanied by varying degrees of reduction. These experimental results show that Sr improves bones from multiple angles. Further investigation of the microbial population revealed that the composition of the gut microbiome was changed due to Sr, with the abundance of 6 of the bacteria showing a different dose dependence with Sr concentration than the control group. To investigate whether alterations in bacterial flora were responsible for the effects of Sr on bone remodeling, a further pearson correlation analysis was done, 4 types of bacteria (Ruminococcaceae_UCG-014, Lachnospiraceae_NK4A136_group, Alistipes and Weissella) were deduced to be the primary contributors to Sr-relieved bone loss. Of these, we focused our analysis on the most firmly associated Ruminococcaceae_UCG-014.

Discussion

To summarize, our current research explores changes in bone mass following Sr intervention in young individuals, and the connection between Sr-altered intestinal flora and potentially beneficial bacteria in the attenuation of bone loss. These discoveries underscore the importance of the "gut-bone" axis, contributing to an understanding of how Sr affects bone quality, and providing a fresh idea for bone mass accumulation in young individuals and thereby preventing disease due to acquired bone mass deficiency.

A Familial Novel Putative-Pathogenic Mutation Identified in Plaque-Psoriasis by a Multigene Panel Analysis

Psoriasis is a chronic multifactorial skin disorder with an immune basis. It is characterized by patches of skin that are usually red, flaky and crusty, and that often release silvery scales. The patches appear predominantly on the elbows, knees, scalp and lower back, although they may also appear on other body areas and severity may be variable. The majority of patients (about 90%) present small patches known as "plaque psoriasis". The roles of environmental triggers such as stress, mechanical trauma and streptococcal infections are well described in psoriasis onset, but much effort is still needed to unravel the genetic component. The principal aim of this study was to use a next-generation sequencing technologies-based approach together with a 96 customized multigene panel in the attempt to determine if there are germline alterations that can explain the onset of the disease, and thus to find associations between genotypes and phenotypes. To this aim, we analyzed a family in which the mother showed mild psoriasis, and her 31-year-old daughter had suffered from psoriasis for several years, whereas an unaffected sister served as a negative control. We found variants already associated directly to psoriasis in the TRAF3IP2 gene, and interestingly we found a missense variant in the NAT9 gene. The use of multigene panels in such a complex pathology such as psoriasis can be of great help in identifying new susceptibility genes, and in being able to make early diagnoses especially in families with affected subjects.

Light-emitting-diode-based antimicrobial photodynamic therapies in the treatment of periodontitis

The use of light-emitting diode (LED)-based photodynamic therapies in the treatment of periodontitis is increasing because these modalities are effective, safe, and painless. They are not subject to acquired drug resistance or environmental issues and are associated with no complications when used appropriately. These light sources have also been used in combination with pharmacological measures to synergize their effects and optimize therapeutic outcomes. This review focuses on optical devices used in treating periodontitis and delineates the current applications of various methods, including their utility and efficacy. The application of LEDs in periodontology is described.

Impact of Chronic Inflammation in Psoriasis on Bone Metabolism

Psoriasis is a chronic inflammatory disease of the skin and joints associated with several comorbidities such as arthritis, diabetes mellitus and metabolic syndrome, including obesity, hypertension and dyslipidaemia, Crohn's disease, uveitis and psychiatric and psychological diseases. Psoriasis has been described as an independent risk factor for cardiovascular diseases and thus patients with psoriasis should be monitored for the development of cardiovascular disease or metabolic syndrome. However, there is mounting evidence that psoriasis also affects the development of osteoporosis, an important metabolic disease with enormous clinical and socioeconomic impact. At present, there are still controversial opinions about the role of psoriasis in osteoporosis. A more in depth analysis of this phenomenon is of great importance for affected patients since, until now, bone metabolism is not routinely examined in psoriatic patients, which might have important long-term consequences for patients and the health system. In the present review, we summarize current knowledge on the impact of psoriatic inflammation on bone metabolism and osteoporosis.

The Gene Expression Analysis of Peripheral Blood Monocytes From Psoriasis Vulgaris Patients With Different Traditional Chinese Medicine Syndromes

Psoriasis is chronic skin disease and an important health concern. Traditional Chinese Medicine (TCM) has shown great promise in the treatment of psoriasis. However, the correlation between TCM Syndromes and genomics of psoriasis has not been evaluated. Here, we analyzed gene expression profiling of monocytes from psoriasis vulgaris patients with different TCM syndrome types to reveal the molecular basis of different psoriasis syndromes. Of the 62 cases of psoriasis vulgaris recruited, 16, 23, and 23 cases were of blood-heat syndrome, blood stasis syndrome, and blood-dryness syndrome, respectively; 10 healthy controls were recruited as controls. Affymertix’s Gene Chip ®clariom D gene chip was used to detect the gene expression profile of peripheral blood monocytes collected from recruited individuals. Compared with the healthy control group, 1570 genes were up-regulated and 977 genes were down-regulated in the psoriasis vulgaris patients group; 798 genes and 108 genes were up- and down-regulated in the blood-heat syndrome group respectively; 319 and 433 genes were up- and down-regulated in the blood-dryness syndrome group, respectively; and 502 and 179 genes were up-and down-regulated in the blood-stasis syndrome group. Our analyses indicated not only common differential genes and pathways between psoriasis syndrome groups and healthy controls, but also syndrome-specific genes and pathways. The results of this study link the three syndromes at the gene level and will be useful for clarifying the molecular basis of TCM syndromes of psoriasis.

Clinical Trial Registration: (http://www.chictr.org.cn/showproj.aspx?proj=4390), identifier (ChiCTR-TRC-14005185).

Role of Epithelium-Derived Cytokines in Atopic Dermatitis and Psoriasis: Evidence and Therapeutic Perspectives

Atopic dermatitis and psoriasis are two of the most common chronic skin conditions. Current target therapies represent viable and safe solutions for the most severe cases of these two dermatoses but, presently, several limitations exist in terms of efficacy and side effects. A new class of products, epithelium-derived cytokines (TSLP, IL-25, IL-33), show an increasing potential for use in target therapy for these patients, and demonstrate a direct link between a generalized inflammatory and oxidative stress status and the human skin. A review was conducted to better understand their role in the aforementioned conditions. Of these three molecules, TSLP led has been most often considered in studies regarding target therapies, and most of the results in the literature are related to this cytokine. These three cytokines share common stimuli and are linked to each other in both acute and chronic phases of these diseases, and have been challenged as target therapies or biomarkers of disease activity. The results lead to the conclusion that epithelium-derived cytokines could represent a therapeutic opportunity for these patients, especially in itch control. Furthermore, they might work better when paired together with currently available therapies or in combination with in-development treatments. Further studies are needed in order to verify the efficacy and safety of the biologic treatments currently under development.

Reduced Serum Levels of Bone Formation Marker P1NP in Psoriasis

Psoriasis is a chronic inflammatory disease of the skin and joints. More recent data emphasize an association with dysregulated glucose and fatty acid metabolism, obesity, elevated blood pressure and cardiac disease, summarized as metabolic syndrome. TNF-α and IL-17, central players in the pathogenesis of psoriasis, are known to impair bone formation. Therefore, the relation between psoriasis and bone metabolism parameters was investigated. Two serum markers of either bone formation-N-terminal propeptide of type I procollagen (P1NP) or bone resorption-C-terminal telopeptide of type I collagen (CTX-I)-were analyzed in a cohort of patients with psoriasis vulgaris. In patients with psoriasis, P1NP serum levels were reduced compared to gender-, age-, and body mass index-matched healthy controls. CTX-I levels were indistinguishable between patients with psoriasis and controls. Consistently, induction of psoriasis-like skin inflammation in mice decreases bone volume and activity of osteoblasts. Moreover, efficient anti-psoriatic treatment improved psoriasis severity, but did not reverse decreased P1NP level suggesting that independent of efficient skin treatment psoriasis did affect bone metabolism and might favor the development of osteoporosis. Taken together, evidence is provided that bone metabolism might be affected by psoriatic inflammation, which may have consequences for future patient counseling and disease monitoring.

IL-33 in Rheumatic Diseases

Interleukin-33 (IL-33) is a nuclear factor mainly expressed in barrier epithelium, endothelial cells, and fibroblast reticular cells. Some inflammatory cells also express IL-33 under certain conditions. The important role of IL-33 in allergic reactions, helminth infection, cancer, tissue fibrosis, chronic inflammation, organ transplantation, and rheumatic immune diseases has been extensively studied in recent years. IL-33 primarily activates various circulating and tissue-resident immune cells, including mast cell, group 2 innate lymphoid cell (ILC2), regulatory T cell (Treg), T helper 2 cell (Th2), natural killer cell (NK cell), and macrophage. Therefore, IL-33 plays an immunomodulatory role and shows pleiotropic activity in different immune microenvironments. The IL-33/serum stimulation-2 (ST2) axis has been shown to have a detrimental effect on rheumatoid arthritis, systemic lupus erythematosus, and other rheumatic diseases. Interestingly, IL-33 also plays a protective role in the repair of barrier epithelium and the activation of Tregs. Therefore, the role of IL-33/ST2 depends on the underlying pathological conditions in rheumatic diseases. This review focuses on the dual role of the IL-33/ST2 axis in rheumatic diseases.

Fracture risks in patients with atopic dermatitis: A nationwide matched cohort study

BACKGROUND

The risk of osteoporosis has been explored in atopic dermatitis (AD). The long-term risk of fractures in patients with AD and the effects of various AD treatments on bone health remain to be elucidated.

OBJECTIVE

To evaluate the long-term risk of fractures in patients with AD.

METHODS

This nationwide matched cohort study was conducted using the National Health Insurance Research Database of Taiwan for the period 1997 to 2013. A total of 36,855 patients with AD and 147,420 reference subjects without AD were identified. Demographic characteristics and comorbidities were compared, and cumulative incidence of fractures was evaluated. Adjusted hazard ratios for fracture risks of AD and various AD treatments were calculated using the Cox proportional hazards model.

RESULTS

A total of 1518 patients (4.12%) in the AD cohort and 5579 patients (3.78%) in the reference cohort had fractures (P = .003). The mean ages were 22.6 years in both groups. The 16-year cumulative incidence of fractures in the AD cohort (8.043%) was significantly higher than that in the reference cohort (7.366%) (P = .002). Severe AD (adjusted hazard ratio [aHR], 1.31; 95% confidence interval [CI], 1.08-1.59) was independently associated with fractures. Other independent risk factors included exposure to topical (aHR, 1.21; 95% CI, 1.05-1.39) or systemic (≥10 mg/d; aHR, 1.62; 95% CI, 1.38-1.91) corticosteroids. Use of disease-modifying antirheumatic drugs (aHR, 0.71; 95% CI, 0.53-0.90) and phototherapy (aHR, 0.73; 95% CI, 0.56-0.95) was associated with a lower risk of fractures. The results were consistent across sensitivity analyses.

CONCLUSION

Patients with AD have a higher incidence of fractures. Severe AD is independently associated with fractures.

Volumetric Bone Mineral Density Measured by HR-pQCT in Patients with Psoriasis or Psoriatic Arthritis: A Systematic Review and Meta-Analysis with Trial Sequential Analysis

Bone health in psoriasis and psoriatic arthritis has been emphasized in recent years. Novel imaging modalities allow investigations into volumetric bone mineral density (vBMD) and bone microstructure in psoriatic patients. However, literature regarding vBMD measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) is inconclusive. We conducted a systematic review and meta-analysis to evaluate vBMD in patients with psoriatic disease. We searched PubMed, EMBASE, Web of Science, and Cochrane Library for relevant observational studies. A random-effects meta-analysis with trial sequential analysis (TSA) was performed. The pooled mean difference (MD) and 95% confidence interval (CI) were calculated. Five studies with 780 patients were included. Patients with psoriatic disease showed a lower average vBMD than controls (MD -14.90; 95% CI -22.90 to -6.89; TSA-adjusted CI -23.77 to -6.03; I² = 41%). Trabecular vBMD and cortical vBMD results were inconclusive because of the small sample size. Patients recruited in Asia and those whose vBMD were measured at the distal radius exhibited a lower average vBMD than controls. Further research should clarify the association of psoriasis with bone microstructure and the underlying pathophysiology.

Clinical predictors of psoriatic arthritis and osteoclast differentiation

Psoriasis and psoriatic arthritis (PsA) are interrelated inflammatory diseases. Psoriasis usually precedes PsA onset and represents a well-established risk factor for PsA development. Bone erosion is a hallmark of PsA, and the contribution of cutaneous psoriatic inflammation in this process has been demonstrated. However, little is still known on the pathogenetic mechanisms that link psoriatic skin to joint damage. Clinical features of psoriatic disease, including specific body site involvement, seem to be important risk predictors of PsA. The aim of this pilot research study was to investigate if psoriatic cutaneous inflammation, affecting these anatomical predictive sites for PsA, could be linked to osteoclast differentiation and activity. Our results showed that psoriasis skin localizations were positively related to the osteoclastogenic profile in psoriatic patients. These results provide new insights into the fascinating skin-joint axis concept.

Inhibition of Sirtuin 3 prevents titanium particle-induced bone resorption and osteoclastsogenesis via suppressing ERK and JNK signaling

Implant-derived wear particles can be phagocytosed by local macrophages, triggering an inflammatory cascade that can drive the activation and recruitment of osteoclasts, thereby inducing peri-prosthetic osteolysis. Efforts to suppress pro-inflammatory cytokine release and osteoclastsogenesis thus represent primary approaches to treating and preventing such osteolysis. Sirtuin 3 (SIRT3) is a NAD⁺-dependent deacetylases that control diverse metabolic processes. However, whether SIRT3 could mitigate wear debris-induced osteolysis has not been reported. Herein we explored the impact of the SIRT3 on titanium particle-induced osteolysis. Tartrate resistant acid phosphatase (TRAP) staining revealed that the inhibition of SIRT3 suppressed nuclear factor-κB ligand (RANKL)-mediated osteoclasts activation in a dose-dependent fashion. Notably, inhibition of SIRT3 also suppressed matrix metallopeptidase 9 (MMP9) and nuclear factor of activated T‐cell cytoplasmic 1 (NFATc1) expression at the mRNA and protein levels, while also inhibiting the mRNA expression of dendritic cell-specific transmembrane protein (DC-STAMP), ATPase H⁺ Transporting V0 Subunit D2 (Atp6v0d2), TRAP and Cathepsin K (CTSK) . In addition, inhibition of SIRT3 suppressed titanium particle-induced tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) expression and prevented titanium particle-induced osteolysis and bone loss in vivo. This inhibition of osteoclasts differentiation was found to be linked to the downregulation and reduced phosphorylation of JNK and ERK. Taken together, inhibition of SIRT3 may be a potential target for titanium particle-induced bone loss.

Adipokines, Cardiovascular Risk, and Therapeutic Management in Obesity and Psoriatic Arthritis

Psoriatic arthritis is a chronic inflammatory disease with skin and joint pathology as the dominant characteristics. Scientific evidence supports its systemic nature and relevant relationship with obesity, metabolic syndrome, and associated conditions. Metabolic syndrome and obesity share common signaling pathways with joint inflammation, reinforcing the idea that adipose tissue is a major contributor to disease development and severity. The adipose tissue is not a mere energy store but also an endocrine organ participating in the immune response. In the search for the best therapeutic strategy for a patient, we should appraise the adipose tissue as an endocrine and immune organ responsible for mild chronic inflammation. Today, our challenge is not only to achieve disease remission but to control the associated comorbidities as well. In light of the high prevalence of obesity in psoriatic arthritis patients and the importance of the adipose tissue in the development of chronic inflammation, we aimed to identify the most relevant articles in this regard published in English until June 2020 using the PubMed database. Search terms included psoriatic arthritis, in combination with metabolic syndrome, obesity, adipokines, cardiovascular disease, and treatment. This review summarizes the current evidence regarding the role of adipose tissue as an adipokine-secreting endocrine organ, discussing its influence on disease development and severity, and ultimately in meeting successful disease management.

Interleukin-17A Interweaves the Skeletal and Immune Systems

The complex crosstalk between the immune and the skeletal systems plays an indispensable role in the maintenance of skeletal homeostasis. Various cytokines are involved, including interleukin (IL)-17A. A variety of immune and inflammatory cells produces IL-17A, especially Th17 cells, a subtype of CD4⁺ T cells. IL-17A orchestrates diverse inflammatory and immune processes. IL-17A induces direct and indirect effects on osteoclasts. The dual role of IL-17A on osteoclasts partly depends on its concentrations and interactions with other factors. Interestingly, IL-17A exerts a dual role in osteoblasts in vitro. IL-17A is a bone-destroying cytokine in numerous immune-mediated bone diseases including postmenopausal osteoporosis (PMOP), rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondylarthritis (axSpA). This review will summarize and discuss the pathophysiological roles of IL-17A on the skeletal system and its potential strategies for application in immune-mediated bone diseases.

The Role of the IL-33/ST2 Immune Pathway in Autoimmunity: New Insights and Perspectives

Interleukin (IL)-33, a member of IL-1 cytokine family, is produced by various immune cells and acts as an alarm to alert the immune system after epithelial or endothelial cell damage during cell necrosis, infection, stress, and trauma. The biological functions of IL-33 largely depend on its ligation to the corresponding receptor, suppression of tumorigenicity 2 (ST2). The pathogenic roles of this cytokine have been implicated in several disorders, including allergic disease, cardiovascular disease, autoimmune disease, infectious disease, and cancers. However, alerted levels of IL-33 may result in either disease amelioration or progression. Genetic variations of IL33 gene may confer protective or susceptibility risk in the onset of autoimmune diseases. The purpose of this review is to discuss the involvement of IL-33 and ST2 in the pathogenesis of a variety of autoimmune disorders, such as autoimmune rheumatic, neurodegenerative, and endocrine diseases.

IL-33/Vitamin D Crosstalk in Psoriasis-Associated Osteoporosis

Patients with psoriasis (Pso) and, in particular, psoriatic arthritis (PsoA) have an increased risk of developing osteoporosis (OP). It has been shown that OP is among the more common pathologies associated with Pso, mainly due to the well-known osteopenizing conditions coexisting in these patients. Pso and OP share common risk factors, such as vitamin D deficiency and chronic inflammation. Interestingly, the interleukin (IL)-33/ST2 axis, together with vitamin D, is closely related to both Pso and OP. Vitamin D and the IL-33/ST2 signaling pathways are closely involved in bone remodeling, as well as in skin barrier pathophysiology. The production of anti-osteoclastogenic cytokines, e.g., IL-4 and IL-10, is promoted by IL-33 and vitamin D, which are stimulators of both regulatory and Th2 cells. IL-33, together with other Th2 cytokines, shifts osteoclast precursor differentiation towards macrophage and dendritic cells and inhibits receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis by regulating the expression of anti-osteoclastic genes. However, while the vitamin D protective functions in OP and Pso have been definitively ascertained, the overall effect of IL-33 on bone and skin homeostasis, because of its pleiotropic action, is still controversial. Emerging evidence suggests a functional link between vitamin D and the IL-33/ST2 axis, which acts through hormonal influences and immune-mediated effects, as well as cellular and metabolic functions. Based on the actions of vitamin D and IL-33 in Pso and OP, here, we hypothesize the role of their crosstalk in the pathogenesis of both these pathologies.

The Crossroads between Infection and Bone Loss

Bone homeostasis, based on a tight balance between bone formation and bone degradation, is affected by infection. On one hand, some invading pathogens are capable of directly colonizing the bone, leading to its destruction. On the other hand, immune mediators produced in response to infection may dysregulate the deposition of mineral matrix by osteoblasts and/or the resorption of bone by osteoclasts. Therefore, bone loss pathologies may develop in response to infection, and their detection and treatment are challenging. Possible biomarkers of impaired bone metabolism during chronic infection need to be identified to improve the diagnosis and management of infection-associated osteopenia. Further understanding of the impact of infections on bone metabolism is imperative for the early detection, prevention, and/or reversion of bone loss. Here, we review the mechanisms responsible for bone loss as a direct and/or indirect consequence of infection.

Osteoporosis in Skin Diseases

Osteoporosis (OP) is defined as a generalized skeletal disease characterized by low bone mass and an alteration of the microarchitecture that lead to an increase in bone fragility and, therefore, an increased risk of fractures. It must be considered today as a true public health problem and the most widespread metabolic bone disease that affects more than 200 million people worldwide. Under physiological conditions, there is a balance between bone formation and bone resorption necessary for skeletal homeostasis. In pathological situations, this balance is altered in favor of osteoclast (OC)-mediated bone resorption. During chronic inflammation, the balance between bone formation and bone resorption may be considerably affected, contributing to a net prevalence of osteoclastogenesis. Skin diseases are the fourth cause of human disease in the world, affecting approximately one third of the world's population with a prevalence in elderly men. Inflammation and the various associated cytokine patterns are the basis of both osteoporosis and most skin pathologies. Moreover, dermatological patients also undergo local or systemic treatments with glucocorticoids and immunosuppressants that could increase the risk of osteoporosis. Therefore, particular attention should be paid to bone health in these patients. The purpose of the present review is to take stock of the knowledge in this still quite unexplored field, despite the frequency of such conditions in clinical practice.

Exacerbated Imiquimod-Induced Psoriasis-Like Skin Inflammation in IRF5-Deficient Mice

Interferon regulatory factors (IRFs) play diverse roles in the regulation of the innate and adaptive immune responses in various diseases. In psoriasis, IRF2 is known to be involved in pathogenesis, while studies on other IRFs are limited. In this study, we investigated the role of IRF5 in psoriasis using imiquimod-induced psoriasis-like dermatitis. Although IRF5 is known to play a critical role in the induction of proinflammatory cytokines by immune cells, such as dendritic cells (DCs), macrophages, and monocytes, IRF5 deficiency unexpectedly exacerbated psoriasiform skin inflammation. The interferon-α and tumor necrosis factor-α mRNA expression levels were decreased, while levels of Th17 cytokines including IL-17, IL-22, and IL-23 were increased in IRF5-deficient mice. Furthermore, IL-23 expression in DCs from IRF5-deficient mice was upregulated both in steady state and after toll-like receptor 7/8 agonist stimulation. Importantly, the expression of IRF4, which is also important for the IL-23 production in DCs, was augmented in DCs from IRF5-deficient mice. Taken together, our results suggest that IRF5 deficiency induces the upregulation of IRF4 in DCs followed by augmented IL-23 production, resulting in the amplification of Th17 responses and the exacerbation of imiquimod-induced psoriasis-like skin inflammation. The regulation of IRF4 or IRF5 expression may be a novel therapeutic approach to psoriasis.

Analysis of microRNA expression in peripheral blood monocytes of three Traditional Chinese Medicine (TCM) syndrome types in psoriasis patients

Background

To analyze the expression of miRNA (microRNA) in peripheral blood mononuclear cells in patients with Psoriasis vulgaris with different TCM syndromes by miRNA chip. It further revealed the micromaterial basis of different syndrome types of psoriasis at the miRNA level.

Methods

Peripheral blood monocytes were collected and prepared from 30 patients with Psoriasis vulgaris (including 9 patients of blood heat syndrome, 8 patients of blood stasis syndrome, and 13 patients of blood dry syndrome) and 9 healthy controls. The miRNA expression profile of peripheral blood monocytes was detected by Agilent Hum miRNA chip.

Results

Compared to the healthy control group, 156 upregulated and 242 downregulated miRNAs were detected in all psoriasis patients. Compared to the healthy control group, 40 miRNAs were upregulated and 44 were downregulated in the blood heat syndrome group. Furthermore, there were 49 upregulated miRNAs and 44 downregulated miRNAs in the dry syndrome group as compared to the healthy control group. Also, 67 miRNAs were upregulated and 154 miRNAs were downregulated in the blood stasis syndrome group as compared to the healthy control group.

Conclusions

There are common different miRNAs and pathways, as well as specific miRNAs between the psoriasis and the healthy control groups.

Trial registration ChiCTR-TRC-14005185 registered on August 8, 2014.

Tissue-resident memory T cells in the skin

PURPOSE

Tissue-resident memory T (T_RM) cells are a newly described subset of memory T cells. The best characterized T_RM cells are CD8+ and express CD103 and CD69. These cells are non-recirculating and persist long term in tissues, providing immediate protection against invading pathogens. However, their inappropriate activation might contribute to the pathogenesis of autoimmune and inflammatory disorders. In the skin, these cells have been described in psoriasis, vitiligo, and melanoma among other diseases.

METHODS

Literature review was done to highlight what is currently known on the phenotype and function of T_RM cells and summarizes the available data describing their role in various cutaneous conditions.

RESULTS

Resolved psoriatic skin and disease-naïve non-lesional skin contain a population of IL-17-producing T_RM cells with shared receptor sequences that recognize common antigens and likely contribute to disease recurrence after cessation of therapy. In vitiligo, T_RM cells produce perforin, granzyme B, and interferon-γ following stimulation by interleukin-15 and collaborate with recirculating memory T cells to maintain disease. In melanoma, increased accumulation of T_RM cells was recently shown to correlate with improved survival in patients undergoing therapy with immune checkpoint inhibitors.

Preventative effects of the partial RANKL peptide MHP1-AcN in a mouse model of imiquimod-induced psoriasis

We recently developed a partial peptide of receptor activator of nuclear factor-кB ligand (RANKL) known as microglial healing peptide 1 (MHP1-AcN), that inhibits Toll-like receptor (TLR)-related inflammation through RANKL/RANK signaling in microglia and macrophages without promoting osteoclast activation. The abnormal activation of TLRs contributes to the initiation and maintenance of psoriasis, which is a chronic inflammatory skin disease that involves the aberrant expression of proinflammatory cytokines and the subsequent dermal γδ T cell and T helper 17 (Th17) cell responses. The inhibition of TLR-mediated inflammation provides an important strategy to treat psoriasis. Here, we examined the preventative effects of MHP1-AcN in a mouse model of imiquimod (a TLR 7/8 agonist)-induced psoriasis. Topical imiquimod application induced psoriasis-like skin lesions on the ear and dorsal skin. Systemic administration of MHP1-AcN by daily subcutaneous injection significantly prevented the development of skin lesions, including erythema, scaling and thickening. Mice treated with MHP1-AcN showed reduced levels of skin Il6 mRNA at 32 h and reduced levels of Il23 and Il17a mRNA at d9. Serum levels of IL-6 and IL-23 were reduced at 32 h, and IL-17A was reduced at d9. These results indicated that MHP1-AcN could decrease imiquimod-induced IL-6, IL-23 and IL-17A production. MHP1-AcN is potentially an alternative treatment for psoriasis.

Possible Roles of IL-33 in the Innate-Adaptive Immune Crosstalk of Psoriasis Pathogenesis

Background

IL-33 belongs to the IL-1 family, playing a role in several biologic processes as well as in the pathogenesis of different diseases, including skin pathologies. It acts as an alarmin, released by damaged cells. Binding to a ST2 receptor, it stimulates many immune cells such as ILC2 and Th2 cells. IL-33/ST2 axis seems to be involved in Th17 response. According to this, a review was performed to analyze if IL-33 even interplay in the onset of psoriasis, a Th1/Th17 inflammatory disease.

Methods

Data obtained from the included articles are study author name, publication date, group studied, clinical and biological variables, laboratory tests, and outcome of interest of the study.

Results

Data are obtained from the 19 studies identified, which assessed the association between IL-33 and psoriasis.

Discussion

It seems to promote the innate-adaptive immune crosstalk: it could induce mast cells and neutrophil response after being released by injured keratinocytes and after stimulation by some cytokines, in particular TNFα, INFγ, and IL-17A. In addition, it seems to be involved from the onset of disease to the development of comorbidities, as psoriatic arthritis.

Conclusion

The core of the future research on psoriasis could be to fully understand the role of this complex cytokine, in order also to find a new therapeutic approach.

Deficiency of Interleukin-1 Receptor Antagonist: A Case with Late Onset Severe Inflammatory Arthritis, Nail Psoriasis with Onychomycosis and Well Responsive to Adalimumab Therapy

DIRA (deficiency of the IL-1Ra) is a rare condition that usually presents in the neonatal period. Patients with DIRA present with systemic inflammation, respiratory distress, joint swelling, pustular rash, multifocal osteomyelitis, and periostitis. Previously, we reported a patient with a novel mutation in IL1RN with a healthy neonatal period, a late-onset of pustular dermatosis, inflammatory arthritis, and excellent response to canakinumab treatment. Herein, we are presenting a new case of late-onset DIRA syndrome, carrying a different mutation and showing different clinical findings. This patient is the first one in the literature with the inflammatory arthritis, nail psoriasis, and onychomycosis and with her remarkable response to monoclonal antibodies. The case responded well and fully recovered after treatment with adalimumab, but not with canakinumab. The DIRA disease can lead to death from multiple organ failures and if recognized early, the treatment with replacement of the deficient protein with biologic agents induces rapid and complete remission. Therefore, clinical symptoms should be learned exactly by the pediatricians, pediatric rheumatologists, and immunologists; and molecular analysis targeting this defect must be performed as early as possible.

Treating to Target(s) With Interleukin-17 Inhibitors

Background:

The treat-to-target (T2T) strategy has become established in several medical specialties as a key guidance to optimal therapeutic decision making. T2T may be effective in the assessment of the biologic class of agents called interleukin (IL)-17 inhibitors, which are emerging as a safe and effective treatment option for autoimmune inflammatory conditions such as plaque psoriasis, psoriatic arthritis (PsA), and ankylosing spondylitis (AS).

Objective:

The objective of this article is to use a T2T approach for the evaluation of the effectiveness and safety of IL-17 inhibitors in the management of patients with plaque psoriasis, PsA, and AS.

Methods:

Following a comprehensive literature search, a full-day meeting was convened to discuss and identify the T2T targets for psoriasis, PsA, and AS. Clinical trial evidence was presented for the approved IL-17 inhibitors—secukinumab, ixekizumab, and brodalumab—to assess whether these data meet T2T safety and efficacy targets.

Results:

All 3 approved agents were significantly superior to placebo and active controls in the achievement of T2T targets for psoriasis. Secukinumab and ixekizumab were likewise associated with significantly better outcomes than controls in the PsA targets, and secukinumab resulted in significant AS target improvements vs placebo. The IL-17 inhibitors were also associated with low rates of serious adverse events and exacerbations of common comorbid conditions.

Conclusion:

Phase III trial results support the T2T benefit and safety of IL-17 inhibitors according to their specific indications for the management of patients with plaque psoriasis, PsA, and AS.

MiR-146a-5p Expression in Peripheral CD14⁺ Monocytes from Patients with Psoriatic Arthritis Induces Osteoclast Activation, Bone Resorption, and Correlates with Clinical Response

In psoriatic arthritis (PsA), progressive bone destruction is mediated by monocyte-derived osteoclasts. MicroRNAs (miRNAs) regulate many pathophysiological processes; however, their function in PsA patient monocytes has not been examined. This study aims to address whether specific miRNAs in CD14⁺ monocytes and monocyte-derived osteoclasts cause active osteoclastogenesis in PsA patients. Candidate miRNAs related to monocyte activation (miR-146a-5p, miR-146b-5p and miR-155-5p) were measured in circulatory CD14⁺ monocytes collected from 34 PsA patients, 17 psoriasis without arthritis (PsO) patients, and 34 normal controls (NCs). CD14⁺ monocytes were cultured with media containing TNF-α and RANKL to differentiate into osteoclasts. Osteoclast differentiation and bone resorption were measured by TRAP immunostaining and dentin slice resorption, respectively. The results showed that the miR-146a-5p expression was higher in PsA patient-derived CD14⁺ monocytes compared to PsO and NCs. Activation and bone resorption were selectively enhanced in osteoclasts from PsA patients, but both were abrogated by RNA interference against miR-146a-5p. More importantly, after clinical improvement using biologics, the increased miR-146a-5p expression in CD14⁺ monocytes from PsA patients was selectively abolished, and associated with blood CRP level. Our findings indicate that miR-146a-5p expression in CD14⁺ monocytes derived from PsA patients correlates with clinical efficacy, and induction of osteoclast activation and bone resorption.

Anti-IL-17 therapy rapidly decreases osteoclast activity in psoriatic patients: a novel quality in addition to its efficacy and safety

BACKGROUND

Psoriasis is a chronic, immune-mediated, inflammatory skin disease where interleukin-17 plays an important role in the underlying pathogenesis. IL-17A is a key driver of pro-osteoclastogenic process, that is abnormal in psoriatic patients. Aim of this study was to investigate in vivo the capability of secukinumab to influence the osteoclastogenesis in psoriatic patients reporting also our experience regarding the effectiveness and safety profile of this biological treatment.

METHODS

Efficacy and tolerability of secukinumab were evaluated after the induction period and 12 weeks. Moreover, to investigate how the cutaneous clinical improvement impacted also on the osteoclastogenic profile of psoriatic patients, the osteoclastogenic assay was performed in 5 secukinumab-treated psoriatic patients, not including psoriatic arthritis, before and after 5 weeks of therapy.

RESULTS

In line with clinical trials, our results confirmed the efficacy, speed of achievement and safety of secukinumab for the treatment of psoriatic patients.

CONCLUSIONS

Moreover, in our experiments secukinumab has demonstrated speed of action also on osteoclastogenic process, reducing the number and activity of osteoclasts only after five weeks of treatment.

Psoriatic arthritis onset in psoriatic patients receiving UV phototherapy in Italy

BACKGROUND

Psoriasis is a chronic, recurrent, and immune-mediated inflammatory disease that affects 2-3% of the world population. A substantial proportion of patients with psoriasis, approximately 40%, develop a form of inflammatory arthritis known as psoriatic arthritis (PsA), the arthritis follows the development of psoriasis, and it will develop simultaneously or possibly before the appearance of skin lesions. The presence of PsA indicates a need for more active intervention rather than purely topical therapies or UV-based therapies. The aim of this multicenter, retrospective, epidemiological study was to estimate the incidence of PsA in psoriatic patients receiving UV treatment as monotherapy.

METHODS

A retrospective epidemiological study was performed in 8 dermatological reference center, located throughout Italy (2 from Northern, 3 from Center, 3 from Southern); a period of 1 year was considered. Data from the overall study population including 326 patients with a diagnosis of psoriasis were analyzed. Furthermore, data coming from follow-up visits, including screening for PsA onset through specific questionnaires were analyzed.

RESULTS

PsA screening was positive in 27 patients (8.3%), whereas PsA diagnosis was confirmed by a rheumatologist in only 22/27 (81.5%) being therefore found in 22/326 (6.7%). Patients diagnosed with PsA had a statistically significantly higher abdominal circumference (96±15.3 vs. 88.9±18.3, P=0.048) and more commonly presented a positive past medical history for phototherapy (90.9% vs. 57.6% P=0.004).

CONCLUSIONS

Our study showed that phototherapy is not able to prevent or slow down the risk of PsA development in psoriatic patients. PsA screening should be always carried out in those patients even if asymptomatic, especially in obese subjects which are at great risk to develop PsA due to their increased systemic inflammatory state.

Psoriasis, Cardiovascular Events, and Biologics: Lights and Shadows

Nowadays, it is well established a link between psoriasis and cardiovascular (CV) diseases. A series of different overlapping mechanisms including inflammation, homeostasis dysregulation, and genetic susceptibility are thought to underlie this association. Advances in understanding the molecular patterns involved in the complex scenario of psoriasis have highlighted a tight correlation with atherosclerosis. Indeed, common profiles are shared in term of inflammatory cytokines and cell types. In the last decade, the management of psoriasis patients has been revolutionized with the introduction of biological therapies, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-12/23, and IL-17 inhibitors. In clinical setting, the effectiveness of these therapies as well as the incidence of CV events is related to the type of biologics. In particular, anti-TNF-α agents seem to reduce these events in psoriasis patients whereas anti-IL-12/23 agents related CV events reduction still remain to clarify. It has to be taken into account that IL-12/23 inhibitors have a shorter post-marketing surveillance period. An even more restricted observational time is available for anti-IL-17 agents. IL-17 is associated with psoriasis, vascular disease, and inflammation. However, IL-17 role in atherosclerosis is still debated, exerting both pro-atherogenic and anti-atherogenic effects depending on the specific context. In this review, we will discuss the differences between the onset of CV events in psoriasis patients, referred to specific biological therapy and the underlying immunological mechanism. Given the development of new therapeutic strategies, the investigation of these inhibitors impact on heart failure outcome is extremely important.

Altered Bone Remodeling in Psoriatic Disease: New Insights and Future Directions

Psoriatic arthritis (PsA) is an inflammatory rheumatic disorder that occurs in patients with psoriasis and predominantly affects musculoskeletal structures, skin, and nails. The etiology of PsA is not well understood but evidence supports an interplay of genetic, immunologic, and environmental factors which promote pathological bone remodeling and joint damage in PsA. Localized and systemic bone loss due to increased activity of osteoclasts is well established in PsA based on animal models and translational studies. In contrast, the mechanisms responsible for pathological bone remodeling in PsA remain enigmatic although new candidate molecules and pathways have been identified. Recent reports have revealed novel findings related to bone erosion and pathologic bone formation in PsA. Many associated risk factors and contributing molecular mechanisms have also been identified. In this review, we discuss new developments in the field, point out unresolved questions regarding the pathogenetic origins of the wide array of bone phenotypes in PsA, and discuss new directions for investigation.