Epigenetics and Vasculitis: a Comprehensive Review

Epigenetics in autoimmune diseases: Unraveling the hidden regulators of immune dysregulation

Autoimmune diseases result from complex interactions between genetic and environmental factors. Recent advances in epigenetic research shed light on the intricate regulatory mechanisms that contribute to the development and progression of such conditions. The present review aims to explore the role of epigenetic modifications, including DNA methylation, histone modifications, and non-coding RNAs, in the context of autoimmune diseases. We discuss the current understanding of epigenetic alterations associated with various autoimmune disorders, their impact on immune cell function, and their potential as innovative therapeutic targets. Additionally, we highlight the main future directions in the field of epigenetics in autoimmunity.

Broadening the clinical spectrum of giant cell arteritis: from the classic cranial to the predominantly extracranial pattern of the disease

INTRODUCTION

Giant cell arteritis (GCA) is a large vessel (LV) vasculitis that affects people aged 50 years and older. Classically, GCA was considered a disease that involved branches of the carotid artery. However, the advent of new imaging techniques has allowed us to reconsider the clinical spectrum of this vasculitis.

AREASCOVERED

This review describes clinical differences between patients with the cranial GCA and those with a predominantly extracranial LV-GCA disease pattern. It highlights differences in the frequency of positive temporal artery biopsy depending on the predominant disease pattern and emphasizes the relevance of imaging techniques to identify patients with LV-GCA without cranial ischemic manifestations. The review shows that so far there are no well-established differences in genetic predisposition to GCA regardless of the predominant phenotype.

EXPERT COMMENTARY

The large branches of the extracranial arteries are frequently affected in GCA. Imaging techniques are useful to identify the presence of 'silent' GCA in people presenting with polymyalgia rheumatica or with nonspecific manifestations. Whether these two different clinical presentations of GCA constitute a continuum in the clinical spectrum of the disease or whether they may be related but are definitely different conditions needs to be further investigated.

Exposome: Epigenetics and autoimmune diseases

Systemic autoimmune diseases are complex conditions characterized by an immune system dysregulation and an aberrant activation against self-antigens, leading to tissue and organ damage. Even though genetic predisposition plays a role, it cannot fully explain the onset of these diseases, highlighting the significant impact of non-heritable influences such as environment, hormones and infections. The exposome represents all those factors, ranging from chemical pollutants and dietary components to psychological stressors and infectious agents. Epigenetics, which studies changes in gene expression without altering the DNA sequence, is a crucial link between exposome and the development of autoimmune diseases. Key epigenetic mechanisms include DNA methylation, histone modifications, and non-coding RNAs. These epigenetic modifications could provide a potential piece of the puzzle in understanding systemic autoimmune diseases and their connection with the exposome. In this work we have collected the most important and recent evidence in epigenetic changes linked to systemic autoimmune diseases (systemic lupus erythematosus, idiopathic inflammatory myopathies, ANCA-associated vasculitis, and rheumatoid arthritis), emphasizing the roles these changes may play in disease pathogenesis, their potential as diagnostic biomarkers and their prospective in the development of targeted therapies.

Aortitis after administration of pegfilgrastim to a healthy donor for peripheral blood stem cell collection

A 45-year-old man who was a sibling donor for allogeneic peripheral blood stem cell transplantation (allo-PBSCT) was administered 7.2 mg of pegfilgrastim for stem cell collection. Peripheral blood stem cells were collected 4 days after administration of pegfilgrastim (Day 4) and 4.32 × 106 /kg of CD34-positive cells per recipient body weight were obtained. Fever of 38 ℃ or higher and left submandibular pain appeared on Day 6. Ultrasonography and contrast-enhanced computed tomography (CT) showed wall thickening of the carotid artery and the abdominal aorta. We carefully excluded the possibilities of cardiovascular and autoimmune diseases by thorough examination, and ultimately diagnosed pegfilgrastim-induced aortitis. The patient's fever resolved rapidly after treatment with prednisolone (PSL) 1 mg/kg. We began to taper PSL after eight days. Sixty-one days after starting PSL, we confirmed that abdominal aortic wall thickening had improved by contrast-enhanced CT. We continued to taper off PSL and stopped 141 days later with no relapse thereafter. This is the first case report of pegfilgrastim-induced aortitis in an allo-PBSCT donor. Careful monitoring is warranted when administering pegfilgrastim to donors even without past medical history.

IgA vasculitis update: Epidemiology, pathogenesis, and biomarkers

Immunoglobulin A vasculitis (IgAV), formerly known as Henoch-Schönlein purpura, is the most common systemic vasculitis in children, characterized by diverse clinical manifestations with a wide spectrum ranging from isolated cutaneous vasculitis to systemic involvement. The incidence of IgAV is geographically and ethnically variable, with a prevalence in autumn and winter, suggesting a driving role that genetic and environmental factors play in the disease. Although IgAV has a certain degree of natural remission, it varies widely among individuals. Some patients can suffer from severe renal involvement and even progress to end-stage renal disease. Its pathogenesis is complex and has not been fully elucidated. The formation of galactose-deficient IgA1 (Gd-IgA1) and related immune complexes plays a vital role in promoting the occurrence and development of IgAV nephritis. In addition, neutrophil activation is stimulated through the binding of IgA to the Fc alpha receptor I expressed on its surface, resulting in systemic vascular inflammation and tissue damage. Starting from the epidemiological characteristics, this article will review the role of immunological factors such as Gd-IgA1, autoantibodies, circulating immune complexes, complement system, cellular immunization, and the contributions of environmental and genetic factors in the pathogenesis of IgAV, and conclude with the major biomarkers for IgAV.

New Insights into the Pathogenesis of Giant Cell Arteritis: Mechanisms Involved in Maintaining Vascular Inflammation

The giant cell arteritis (GCA) pathophysiology is complex and multifactorial, involving a predisposing genetic background, the role of immune aging and the activation of vascular dendritic cells by an unknown trigger. Once activated, dendritic cells recruit CD4 T cells and induce their activation, proliferation and polarization into Th1 and Th17, which produce interferon-gamma (IFN-γ) and interleukin-17 (IL-17), respectively. IFN-γ triggers the production of chemokines by vascular smooth muscle cells, which leads to the recruitment of additional CD4 and CD8 T cells and also monocytes that differentiate into macrophages. Recent data have shown that IL-17, IFN-γ and GM-CSF induce the differentiation of macrophage subpopulations, which play a role in the destruction of the arterial wall, in neoangiogenesis or intimal hyperplasia. Under the influence of different mediators, mainly endothelin-1 and PDGF, vascular smooth muscle cells migrate to the intima, proliferate and change their phenotype to become myofibroblasts that further proliferate and produce extracellular matrix proteins, increasing the vascular stenosis. In addition, several defects in the immune regulatory mechanisms probably contribute to chronic vascular inflammation in GCA: a defect in the PD-1/PD-L1 pathway, a quantitative and qualitative Treg deficiency, the implication of resident cells, the role of GM-CSF and IL-6, the implication of the NOTCH pathway and the role of mucosal‑associated invariant T cells and tissue‑resident memory T cells.

Age as a risk factor in vasculitis

Two vasculitides, giant cell arteritis (GCA) and Takayasu arteritis (TAK), are recognized as autoimmune and autoinflammatory diseases that manifest exclusively within the aorta and its large branches. In both entities, the age of the affected host is a critical risk factor. TAK manifests during the 2nd-4th decade of life, occurring while the immune system is at its height of performance. GCA is a disease of older individuals, with infrequent cases during the 6th decade and peak incidence during the 8th decade of life. In both vasculitides, macrophages and T cells infiltrate into the adventitia and media of affected vessels, induce granulomatous inflammation, cause vessel wall destruction, and reprogram vascular cells to drive adventitial and neointimal expansion. In GCA, abnormal immunity originates in an aged immune system and evolves within the aged vascular microenvironment. One hallmark of the aging immune system is the preferential loss of CD8⁺ T cell function. Accordingly, in GCA but not in TAK, CD8⁺ effector T cells play a negligible role and anti-inflammatory CD8⁺ T regulatory cells are selectively impaired. Here, we review current evidence of how the process of immunosenescence impacts the risk for GCA and how fundamental differences in the age of the immune system translate into differences in the granulomatous immunopathology of TAK versus GCA.

Critical Role of Gut Microbiota and Epigenetic Factors in the Pathogenesis of Behçet's Disease

Behçet’s disease (BD) is a chronic refractory multisystem autoinflammatory disease, characterized by typical clinical features of non-specific vasculitis, oral and genital ulcers, uveitis, as well as skin lesions. The exact etiopathogenesis of BD remains unknown, existing studies have indicated that genetics and environmental factors contribute to the increased development of BD. Recently, several studies have shown that external environmental factors can affect the process of epigenetic modification, and abnormalities of epigenetic factors have been confirmed to be involved in the occurrence of BD. At the same time, abnormalities of gut microbiota (GM) in the body, have also been confirmed to participate in the pathogenesis of BD by regulating the balance of Th17/Tregs. This article reviews the pathogenesis of BD and summarizes numerous clinical studies, focusing on the mechanism of GM and epigenetic factors impacting on BD, and providing new ideas for further elucidating the pathogenesis of BD.

Implication of epigenetic factors in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease that resulted from the severe destruction of the insulin-producing β cells in the pancreases of individuals with a genetic predisposition. Genome-wide studies have identified HLA and other risk genes associated with T1D susceptibility in humans. However, evidence obtained from the incomplete concordance of diabetes incidence among monozygotic twins suggests that environmental factors also play critical roles in T1D pathogenesis. Epigenetics is a rapidly growing field that serves as a bridge to link T1D risk genes and environmental exposures, thereby modulating the expression of critical genes relevant to T1D development beyond the changes of DNA sequences. Indeed, there is compelling evidence that epigenetic changes induced by environmental insults are implicated in T1D pathogenesis. Herein, we sought to summarize the recent progress in terms of epigenetic mechanisms in T1D initiation and progression, and discuss their potential as biomarkers and therapeutic targets in the T1D setting.

Association between Kawasaki Disease and Prenatal Exposure to Ambient and Industrial Air Pollution: A Population-Based Cohort Study

BACKGROUND

Environmental factors may contribute to the development of Kawasaki disease in children, but prenatal environmental exposures are understudied.

OBJECTIVE

We used a population-based cohort to investigate whether prenatal exposure to outdoor air pollution is associated with the incidence of Kawasaki disease in childhood.

METHODS

We performed a longitudinal cohort study of all children born in Quebec, Canada, between 2006 and 2012. Children were followed for Kawasaki disease from birth until 31 March 2018. We assigned prenatal air pollutant exposure according to the residential postal code at birth. The main exposure was annual average concentration of ambient fine particulate matter [PM ≤2.5μm in aerodynamic diameter (PM2.5) and nitrogen dioxide (NO2) from satellite-based estimates and land-use regression models. As secondary exposures, we considered industrial PM2.5, NO2, and sulfur dioxide (SO2) emissions estimated from dispersion models. We estimated hazard ratios (HRs) using Cox proportional hazards models, adjusted for maternal age, parity, sex, multiple birth, maternal smoking during pregnancy, socioeconomic status, birth year, and rural residence. We considered single and multipollutant models. We performed several sensitivity analyses, including assessing modifying effects of maternal comorbidities (e.g., diabetes, preeclampsia).

RESULTS

The cohort comprised 505,336 children, including 539 with Kawasaki disease. HRs for each interquartile range increase in ambient air pollution were 1.16 (95% CI: 0.96, 1.39) for PM2.5 and 1.12 (95% CI: 0.96, 1.31) for NO2. For industrial air pollution, HRs were 1.07 (95% CI: 1.01, 1.13) for SO2, 1.09 (95% CI: 0.99, 1.20) for NO2, and 1.01 (95% CI: 0.97, 1.05) for PM2.5. In multipollutant models, associations for ambient PM2.5 and NO2 (i.e., from all sources) were robust to adjustment for industrial pollution, and vice versa.

DISCUSSION

In this population-based cohort study, both prenatal exposure to ambient and industrial air pollution were associated with the incidence of Kawasaki disease in childhood. Further studies are needed to consolidate the observed associations. https://doi.org/10.1289/EHP6920.

Platelets in Skin Autoimmune Diseases

Systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and small vessel vasculitis are three autoimmune diseases frequently manifested in the skin. They share common pathogenic features, including production of autoantibodies, loss of tolerance to self-antigens, tissue necrosis and fibrosis, vasculopathy and activation of the coagulation system. Platelets occupy a central part within the coagulation cascade and are well-recognized for their hemostatic role. However, recent cumulative evidence implicates their additional and multifaceted immunoregulatory functions. Platelets express immune receptors and they store growth factors, cytokines, and chemokines in their granules enabling a significant contribution to inflammation. A plethora of activating triggers such as damage associated molecular patterns (DAMPs) released from damaged endothelial cells, immune complexes, or complement effector molecules can mediate platelet activation. Activated platelets further foster an inflammatory environment and the crosstalk with the endothelium and leukocytes by the release of immunoactive molecules and microparticles. Further insight into the pathogenic implications of platelet activation will pave the way for new therapeutic strategies targeting autoimmune diseases. In this review, we discuss the inflammatory functions of platelets and their mechanistic contribution to the pathophysiology of SSc, ANCA associated small vessel vasculitis and other autoimmune diseases affecting the skin.

Association between rs1800795 polymorphisms in the interleukin-6 gene and vasculitis: A meta-analysis

Interleukin (IL)-6 is associated with the development and progression of vasculitis, and inhibitors of this cytokine are used to treat this disease. Polymorphisms of the promoter region of IL-6 are associated with the production and expression of IL-6. The aim of this study was to perform a meta-analysis of eligible studies to derive a precise estimate of the association between IL6 polymorphisms and susceptibility to vasculitis. A meta-analysis was conducted to identify the associations between IL6 rs1800795 (-174 G/C) polymorphisms and vasculitis. A total of 13 studies involving 1,294 vasculitis patients and 1,594 controls were considered in the meta-analysis. There were significant associations between IL6 rs1800795 polymorphisms and vasculitis in allele contrast, dominant genetic model, and heterozygote vs. dominant homozygote comparison (OR 0.80, 95% CI 0.67-0.94, P =0.009 and OR 0.76, 95% CI 0.63-0.92, P =0.005, respectively). In subgroup analysis based on subtype, there were significant associations between IL6 polymorphisms and susceptibility in large and medium vessel vasculitis, but not in small and variable vessel vasculitis. The GC genotype of IL6 rs1800795 was suggested by the analyses to be related to low prevalence of vasculitis, especially for large and medium vessels.

Kawasaki disease OX40-OX40L axis acts as an upstream regulator of NFAT signaling pathway

BACKGROUND

We investigated a costimulatory molecule OX40-OX40L acting as an upstream regulator to regulate the nuclear factor of activated T cell (NFAT) in the acute phase of Kawasaki disease (KD).

METHODS

One hundred and one samples were collected and divided into six groups: coronary artery lesion (KD-CAL) before intravenous immunoglobulin (IVIG), KD-CAL after IVIG, KD without CAL (KD-nCAL) before IVIG, KD-nCAL after IVIG, fever of unknown (Fou), and Healthy. In vitro OX40-stimulating and OX40L-inhibiting tests were conducted in Healthy and KD groups, respectively. Both the messenger RNA (mRNA) and protein expression levels of OX40, OX40L, NFAT1, and NFAT2 were investigated using quantitative reverse transcription PCR and immunoblotting assay, respectively.

RESULTS

The mRNA and protein expression levels of NFAT1, NFAT2, OX40, and OX40L were significantly increased in KD-CAL and KD-nCAL groups before IVIG compared with Fou and Healthy groups and decreased after IVIG. A positive correlation was found between them in KD. In vitro OX40-stimulating test demonstrated the significantly increased mRNA and protein expression levels of NFAT1 and NFAT2 in the peripheral blood mononuclear cells of the Healthy group. Meanwhile, OX40L-inhibiting test showed significantly decreased expression levels of NFAT1 and NFAT2 in the KD group.

CONCLUSION

OX40-OX40L acts as an upstream regulator in the NFAT signaling pathway involved in KD.

Comprehensive analyses of DNA methylation and gene expression profiles of Kawasaki disease

OBJECTIVE

Kawasaki disease (KD) is a childhood febrile vasculitis with unknown etiology. Epigenetic regulation in the gene expression dynamics has become increasingly important in KD. Thus, we performed an integrated analysis of DNA methylation and gene expression data to identify novel molecular mechanisms and key functional genes in KD.

METHODS

DNA methylation (GSE84624) and gene expression (GSE68004) datasets were downloaded from Gene Expression Omnibus. Methylated-differentially expressed genes (mDEGs) were documented as the overlapping genes between the differentially methylated genes (DMGs) in GSE84624 and differentially expressed genes (DEGs) in GSE68004. Functional enrichment analyses of the mDEGs were conducted using DAVID database. Protein-protein interaction (PPI) network was then constructed to obtain the hub genes involved in KD using STRING database.

RESULTS

A total of 1389 DMGs and 1362 DEGs were screened out between KD and control samples. Overlapping of them resulted in four hypermethylated/downregulated and 187 hypomethylated/upregulated genes. These mDEGs were mainly enriched in inflammation response, innate immune response, and blood coagulation, and signaling pathways such as platelet activation, osteoclast differentiation, and chemokine signaling pathway. PPI network analyses identified MAPK14 and PHLPP1 as the hub genes involved in KD, which could distinguish KD from other common pediatric febrile diseases. In addition, the methylation and expression levels of MAPK14 and PHLPP1 were validated in other independent datasets.

CONCLUSION

This study provides an integrated view of interactions among DNA methylation and gene expression in patients with KD. MAPK14 and PHLPP1 are the key genes influenced by methylation and may serve as candidate biomarkers for KD.

Early childhood exposure to maternal smoking and Kawasaki Disease: A longitudinal survey in Japan

Kawasaki disease is the leading cause of acquired childhood heart disease in most developed countries, but the etiology of the disease is unknown. An aberrant immune response to some environmental triggers may play a role and involuntary exposure to tobacco smoke can alter immune functions. We thus prospectively examined the association between early childhood exposure to maternal smoking and the incidence of Kawasaki disease. We used a large, nationwide population-based longitudinal survey ongoing since 2010 and restricted participants to a total of 38,444 children for whom information on maternal smoking was available. Maternal smoking status was ascertained at 6months of age, and responses to questions about hospital admission for Kawasaki disease between the ages of 6 and 30months were used as outcome. We conducted binomial log-linear regression analyses adjusting for children's, parental, and residential factors with children of non-smoking mothers as our reference group. Maternal smoking increased the risk of admission, in particular for the period between 6 and 18months of age, in a dose-dependent manner. Compared with children of non-smoking mothers, the children of mothers who smoked had a risk ratio of 1.83 (95% confidence interval: 1.06, 3.35) for hospital admissions between 6 and 30months of age and a risk ratio of 2.69 (95% confidence interval: 1.56, 4.64) for hospital admissions between 6 and 18months of age. Early childhood exposure to maternal smoking may increase the risk of Kawasaki disease hospitalizations in childhood.

Decreased DNA methyltransferases expression is associated with coronary artery lesion formation in Kawasaki disease

Background: Kawasaki disease (KD) is the most common acute coronary vasculitis to occur in children. Although we have uncovered global DNA hypomethylation in KD, its underlying cause remains uncertain. In this study, we performed a survey of transcript levels of DNA methyltransferases and demethylases in KD patients. Materials and Methods: We recruited 145 participants for this study. The chip studies consisted of 18 KD patients that were analyzed before undergoing intravenous immunoglobulin (IVIG) treatment and at least 3 weeks after IVIG treatment, as well as 36 control subjects, using Affymetrix GeneChip® Human Transcriptome Array 2.0. An additional study of 91 subjects was performed in order to validate real-time quantitative PCR. Results: In our microarray study, the mRNA levels of DNMT1 and DNMT3A were significantly lower while TET2 was higher in acute-stage KD patients compared to the healthy controls. Through PCR validation, we observed that the expression of DNMT1 and TET2 are consistent with the Transcriptome Array 2.0 results. Furthermore, we observed significantly lower DMNT1 mRNA levels following IVIG treatment between those who developed CAL and those who did not. Conclusion: Our findings provide an evidence of DNA methyltransferases and demethylases changes and are among the first report that transient DNA hypomethylation is induced during acute inflammatory phase of Kawasaki disease.

Recent Advances in Giant Cell Arteritis

PURPOSE OF REVIEW

Giant cell arteritis (GCA) is the most common systemic vasculitis. GCA is categorized as a granulomatous vasculitis of large and medium size vessels. Majority of the symptoms and signs of GCA result from involvement of the aorta and its branches intra- and extracranial. Temporal artery biopsy continues to be the cardinal diagnostic procedure despite new imaging modalities for diagnosing GCA with cranial involvement. Great advances in awareness have led to improvement in preventing irreversible vision loss due to early diagnosis.

RECENT FINDINGS

The cause of GCA has not been elucidated but major progress has been made in the knowledge of its pathogenesis leading to new therapeutic targets, particularly inhibition of interleukin 6. IL 6 plays a key role in the regulation of TH17/Tregs imbalance in GCA and appears to correlate with clinical disease activity in GCA. All of this has led to the first FDA (food and drug administration) approved treatment for GCA, Tocilizumab. Abatacept and Ustekinumab are promising targets for therapy in LVV but still need further research. This paper is a review of the recent progress in the understanding of GCA pathogenesis, diagnosis, treatment, and prognosis.

Cross-phenotype analysis of Immunochip data identifies KDM4C as a relevant locus for the development of systemic vasculitis

OBJETIVE

Systemic vasculitides represent a heterogeneous group of rare complex diseases of the blood vessels with a poorly understood aetiology. To investigate the shared genetic component underlying their predisposition, we performed the first cross-phenotype meta-analysis of genetic data from different clinically distinct patterns of vasculitis.

METHODS

Immunochip genotyping data from 2465 patients diagnosed with giant cell arteritis, Takayasu's arteritis, antineutrophil cytoplasmic antibody-associated vasculitis or IgA vasculitis as well as 4632 unaffected controls were analysed to identify common susceptibility loci for vasculitis development. The possible functional consequences of the associated variants were interrogated using publicly available annotation data.

RESULTS

The strongest association signal corresponded with an intergenic polymorphism located between HLA-DQB1 and HLA-DQA2 (rs6932517, P=4.16E-14, OR=0.74). This single nucleotide polymorphism is in moderate linkage disequilibrium with the disease-specific human leucocyte antigen (HLA) class II associations of each type of vasculitis and could mark them. Outside the HLA region, we identified the KDM4C gene as a common risk locus for vasculitides (highest peak rs16925200, P=6.23E-07, OR=1.75). This gene encodes a histone demethylase involved in the epigenetic control of gene expression.

CONCLUSIONS

Through a combined analysis of Immunochip data, we have identified KDM4C as a new risk gene shared between systemic vasculitides, consistent with the increasing evidences of the crucial role that the epigenetic mechanisms have in the development of complex immune-mediated conditions.

Autoimmunity in 2016

The number of peer-reviewed articles published during the 2016 solar year and retrieved using the "autoimmunity" key word remained stable while gaining a minimal edge among the immunology articles. Nonetheless, the quality of the publications has been rising significantly and, importantly, acquisitions have become available through scientific journals dedicated to immunology or autoimmunity. Major discoveries have been made in the fields of systemic lupus erythematosus, rheumatoid arthritis, autoimmunity of the central nervous system, vasculitis, and seronegative spondyloarthrithritides. Selected examples include the role of IL17-related genes and long noncoding RNAs in systemic lupus erythematosus or the effects of anti-pentraxin 3 (PTX3) in the treatment of this paradigmatic autoimmune condition. In the case of rheumatoid arthritis, there have been reports of the role of induced regulatory T cells (iTregs) or fibrocytes and T cell interactions with exciting implications. The large number of studies dealing with neuroimmunology pointed to Th17 cells, CD56(bright) NK cells, and low-level TLR2 ligands as involved in multiple sclerosis, along with a high salt intake or the micriobiome-derived Lipid 654. Lastly, we focused on the rare vasculitides to which numerous studies were devoted and suggested that unsuspected cell populations, including monocytes, mucosal-associated invariant T cells, and innate lymphoid cells, may be crucial to ANCA-associated manifestations. This brief and arbitrary discussion of the findings published in 2016 is representative of a promising background for developments that will enormously impact the work of laboratory scientists and physicians at an exponential rate.

Intrauterine and Early Postnatal Exposure to Particulate Air Pollution and Kawasaki Disease: A Nationwide Longitudinal Survey in Japan

OBJECTIVES

To examine the effects of prenatal and postnatal exposure to particulate matter on Kawasaki disease (KD) occurrence, using data from a nationwide population-based longitudinal survey in Japan that began in 2010.

STUDY DESIGN

Prenatal and postnatal suspended particulate matter concentrations were obtained at municipality level and assigned to participants based on their municipality of birth. We analyzed data from 30 367 participants with data on either exposure period. We used hospital admission for KD from 6 to 30 months of age as the main outcome of interest. We conducted a multilevel logistic regression analysis, adjusting for individual and municipality-level variables.

RESULTS

Children who were exposed to higher levels of suspended particulate matter, in particular during pregnancy, were more likely to be hospitalized for KD. The ORs for ≥25 µg/m³ exposure compared with <20 µg/m³ exposure were 1.59 (95% CI 1.06, 2.38) for prenatal exposure and 1.41 (0.82, 2.41) for postnatal exposure. Prenatal exposure during mid-to-late gestation seemed to be more relevant for the increased risk.

CONCLUSIONS

Early life exposure to particulate air pollution, in particular during pregnancy, is associated with an increased risk of KD hospital admission in early childhood in a nationally representative sample in Japan.

Tacrolimus therapy for dermal arteritis of the nasal philtrum refractory to surgery and anti-inflammatory therapy (doxycycline/niacinamide and topical fluocinolone) in a dog

BACKGROUND

Dermal arteritis of the nasal philtrum is a rarely reported condition commonly affecting large breed dogs.

OBJECTIVE

To describe the effective treatment of nasal philtrum arteritis with topical tacrolimus in one dog.

ANIMAL

A 9-year-old, intact male German shorthair pointer dog was presented with well-demarcated deep erythematous ulcers targeting exclusively the skin of the nasal philtrum, accompanied by frequent series of haemorrhage.

METHODS

Complete blood count, serum chemistry profile, urinalysis, histopathological examination and immunohistochemistry of skin biopsies.

RESULTS

The presence of a V-shaped ulcer with subendothelial spindle cell proliferation resulting in stenosis of dermal arteries and arterioles on histological evaluation, together with a well-demarcated deep nasal philtrum ulcer was consistent with arteritis of the nasal philtrum. Treatment was initiated with twice daily oral doxycycline and niacinamide in conjunction with topical fluocinolone cream. Over the course of two years, the lesions progressed with frequent bleeding episodes. A novel surgical approach provided deep resection of all grossly affected tissue; four months later a recurrence of fissures and occasional mild bleeding from the original site was noted and there was no improvement after another two months of oral doxycycline/niacinamide and topical fluocinolone treatment. Topical application of 0.1% tacrolimus twice daily resulted in complete healing of the ulceration and normalization of the epidermis. Over the subsequent 15 months, the dog's lesions remained in remission with topical tacrolimus application twice daily.

CONCLUSIONS AND CLINICAL IMPORTANCE

Topical tacrolimus ointment appeared effective at inducing and maintaining lesion remission in this dog with nasal philtrum arteritis.

The epigenetic mechanism for discordance of autoimmunity in monozygotic twins

Monozygotic twins share an identical DNA sequence but are not truly "identical". In fact, when it comes to health and disease, they may often display some level of phenotypic discordance. The cause of this discordance is often unknown. Epigenetic modifications such as DNA methylation, histone modification, and microRNAs-mediated regulation regulate gene expression and are sensitive to external stimuli. These modifications may be seen to bridge the gap between genetics and the environment. Over the years, the importance of epigenetics as a primary mechanism for the role that the environment plays in defining phenotype has been increasingly appreciated. Mechanisms of epigenetics include DNA methylation, histone modifications and microRNAs. Discordance rates in monozygotic twins vary depending on the specific condition, from 11% in SLE to 64% in psoriasis and 77% in PBC. Other autoimmune diseases in which discordance is found among monozygotic twins has also been studied include type 1 diabetes, multiple sclerosis, rheumatoid arthritis, dermatomyositis and systemic sclerosis. In some cases, the differences in various epigenetic modifications is slight, even though the concordance rate is low, suggesting that epigenetics is not the only factor that needs to be considered. Nonetheless, the study of phenotypic discordance in monozygotic twins may shed light on the pathogenesis of autoimmune diseases and contribute to the development of new methodologies for the diagnosis and treatment of these diseases.

The Immune Response and the Pathogenesis of Idiopathic Inflammatory Myositis: a Critical Review

The pathogenesis of idiopathic inflammatory myositis (IIMs, including polymyositis and dermatomyositis) remains largely enigmatic, despite advances in the study of the role played by innate immunity, adaptive immunity, genetic predisposition, and environmental factors in an orchestrated response. Several factors are involved in the inflammatory state that characterizes the different forms of IIMs which share features and mechanisms but are clearly different with respect to the involved sites and characteristics of the inflammation. Cellular and non-cellular mechanisms of both the immune and non-immune systems have been identified as key regulators of inflammation in polymyositis/dermatomyositis, particularly at different stages of disease, leading to the fibrotic state that characterizes the end stage. Among these, a special role is played by an interferon signature and complement cascade with different mechanisms in polymyositis and dermatomyositis; these differences can be identified also histologically in muscle biopsies. Numerous cellular components of the adaptive and innate immune response are present in the site of tissue inflammation, and the complexity of idiopathic inflammatory myositis is further supported by the involvement of non-immune mechanisms such as hypoxia and autophagy. The aim of this comprehensive review is to describe the major pathogenic mechanisms involved in the onset of idiopathic inflammatory myositis and to report on the major working hypothesis with therapeutic implications.

[Research advances in association between vitamin D and Kawasaki disease and related mechanisms of action]

Vitamin D is an important steroid hormone, which has a wide biological effect and is the protective factor against cardiovascular disease and other diseases. At present, the etiology and pathogenesis of Kawasaki disease (KD) remain unknown, but recent studies have shown that vitamin D insufficiency or deficiency is associated with KD. Vitamin D insufficiency or deficiency may affect KD via its influence on inflammatory response, adipokine, endothelial function, platelet function, and DNA methylation and increase the risk of coronary artery lesions. This article reviews the research advances in the association between vitamin D and KD and possible mechanisms of action.

Histone modification signature at myeloperoxidase and proteinase 3 in patients with anti-neutrophil cytoplasmic autoantibody-associated vasculitis

BACKGROUND

Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is a systemic autoimmune disease characterized by destructive vascular inflammation. Two prominent ANCA autoantigens are myeloperoxidase (MPO) and proteinase 3 (PR3), and transcription of MPO and PRTN3, the genes encoding the autoantigens, is associated with disease activity. We investigated whether patients with AAV have alterations in histone modifications, particularly those associated with transcriptional activation, at MPO and PRTN3.

RESULTS

We identified a network of genes regulating histone modifications that were differentially expressed in AAV patients compared to healthy controls. We focused on four genes (EHMT1 and EHMT2, ING4, and MSL1) and found their expression correlated with expression of MPO and PRTN3. Methylation of histone H3K9, catalyzed by EHMT1 and EHMT2 and associated with gene silencing, was most depleted at MPO and PRTN3 in patients with active disease and the highest MPO and PRTN3 expression. Acetylation of histone H4K16, modified by complexes containing ING4 and MSL1 and associated with gene activation, was most enriched at MPO and PRTN3 in patients with active disease and the highest MPO and PRTN3 expression. Methylation at H3K4, a mark of transcriptional activation, was enriched at MPO and PRTN3 in patients and healthy controls.

CONCLUSIONS

MPO and PRTN3 in neutrophils of AAV patients with active disease have a distinct pattern of histone modifications, which implicates epigenetic mechanisms in regulating expression of autoantigen genes and suggests that the epigenome may be involved in AAV pathogenesis.

Classifying aging as a disease in the context of ICD-11

Aging is a complex continuous multifactorial process leading to loss of function and crystalizing into the many age-related diseases. Here, we explore the arguments for classifying aging as a disease in the context of the upcoming World Health Organization's 11th International Statistical Classification of Diseases and Related Health Problems (ICD-11), expected to be finalized in 2018. We hypothesize that classifying aging as a disease with a "non-garbage" set of codes will result in new approaches and business models for addressing aging as a treatable condition, which will lead to both economic and healthcare benefits for all stakeholders. Actionable classification of aging as a disease may lead to more efficient allocation of resources by enabling funding bodies and other stakeholders to use quality-adjusted life years (QALYs) and healthy-years equivalent (HYE) as metrics when evaluating both research and clinical programs. We propose forming a Task Force to interface the WHO in order to develop a multidisciplinary framework for classifying aging as a disease with multiple disease codes facilitating for therapeutic interventions and preventative strategies.