CD40 ligand gene and Kawasaki disease

Endothelial Dysfunction: Molecular Mechanisms and Therapeutic Strategies in Kawasaki Disease

The endothelium plays a key role in regulating vascular homeostasis by responding to a large spectrum of chemical and physical stimuli. Vasculitis is a group of inflammatory conditions affecting the vascular bed, and it is known that they are strongly linked to endothelial dysfunction (ED). Kawasaki disease (KD) is one childhood systemic vasculitis, and it represents the leading cause of acquired cardiac disease in children due to coronary damage and subsequent cardiovascular (CV) morbidity and mortality. We aimed to focus on the actual knowledge of ED in the pathogenesis of KD and its practical implications on therapeutical strategies to limit cardiovascular complications. Understanding ED in KD provides insight into the underlying mechanisms and identifies potential therapeutic targets to mitigate vascular damage, ultimately improving cardiovascular outcomes in both the acute and chronic stages of the disease. However, research gaps remain, particularly in translating findings from animal models into clinical applications for cardiovascular lesions and related morbidity in KD patients.

Whole-exome sequencing reveals Kawasaki disease susceptibility genes and their association with coronary artery lesion

Objective

This study aimed to explore Kawasaki disease (KD) susceptibility genes and their complications like coronary artery lesions (CAL) using whole exome sequencing (WES).

Methods

Between April 1, 2021, and December 31, 2022, our study included 55 pediatric patients diagnosed KD at our center, alongside a cohort of healthy children who sought medical care at our institution during the same timeframe. We extracted peripheral blood DNA from all participants and employed the advanced high-throughput Illumina Next-Generation Sequencing technology for comprehensive analysis. Through bioinformatics evaluation, we identified potential susceptibility genes. Moreover, from the 55 KD patients, we selected 15 for the CAL group and 40 for the non-CAL group. We aimed to investigate whether there were significant differences in the allele frequencies of the targeted susceptibility genes between these subgroups, to explore the risk alleles associated with the development of CAL in KD.

Results

HLA-DRB1 rs17882084 and IL6ST rs781455079 genotypes and alleles differed significantly between KD and non-KD (P < 0.05). No differences existed for IL17RC rs143781415 and VEGFB rs776229557 (P > 0.05). No differences in HLA-DRB1 rs17882084, IL6ST rs781455079, and VEGFB rs776229557 genotypes existed between CAL and non-CAL groups (P > 0.05). However, the IL17RC rs143781415 genotype differed significantly between them (P < 0.05).

Conclusions

HLA-DRB1 rs17882084 and IL6ST rs781455079 genotypes may be potential KD susceptibility gene candidates. Specifically, HLA-DRB1 rs17882084 GA genotype and A allele, and IL6ST rs781455079 TC genotype and C allele may increase KD risk. Additionally, the IL17RC rs143781415 genotype may increase CAL risk in KD patients.

Identification of novel locus associated with coronary artery aneurysms and validation of loci for susceptibility to Kawasaki disease

Kawasaki disease (KD) is a paediatric vasculitis associated with coronary artery aneurysms (CAA). Genetic variants influencing susceptibility to KD have been previously identified, but no risk alleles have been validated that influence CAA formation. We conducted a genome-wide association study (GWAS) for CAA in KD patients of European descent with 200 cases and 276 controls. A second GWAS for susceptibility pooled KD cases with healthy paediatric controls from vaccine trials in the UK (n = 1609). Logistic regression mixed models were used for both GWASs. The susceptibility GWAS was meta-analysed with 400 KD cases and 6101 controls from a previous European GWAS, these results were further meta-analysed with Japanese GWASs at two putative loci. The CAA GWAS identified an intergenic region of chromosome 20q13 with multiple SNVs showing genome-wide significance. The risk allele of the most associated SNV (rs6017006) was present in 13% of cases and 4% of controls; in East Asian 1000 Genomes data, the allele was absent or rare. Susceptibility GWAS with meta-analysis with previously published European data identified two previously associated loci (ITPKC and FCGR2A). Further meta-analysis with Japanese GWAS summary data from the CASP3 and FAM167A genomic regions validated these loci in Europeans showing consistent effects of the top SNVs in both populations. We identified a novel locus for CAA in KD patients of European descent. The results suggest that different genes determine susceptibility to KD and development of CAA and future work should focus on the function of the intergenic region on chromosome 20q13.

The up-to-date pathophysiology of Kawasaki disease

Kawasaki disease (KD) is an acute systemic vasculitis of an unknown aetiology. A small proportion of children exposed to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) or infected by Yersinia reproducibly develop principal symptoms of KD in various ethnic areas, but not in all studies. These microbes provoke a rapid cell‐damaging process, called ‘pyroptosis’, which is characterised by a subsequent release of proinflammatory cellular components from damaged endothelial and innate immune cells. In agreement with these molecular events, patients with KD show elevated levels of damage‐associated molecular patterns derived from cell death. In addition, an overwhelming amount of oxidative stress‐associated molecules, including oxidised phospholipids or low‐density lipoproteins, are generated as by‐products of inflammation during the acute phase of the disease. These molecules induce abnormalities in the acquired immune system and activate innate immune and vascular cells to produce a range of proinflammatory molecules such as cytokines, chemokines, proteases and reactive oxygen species. These responses further recruit immune cells to the arterial wall, wherein inflammation and oxidative stress closely interact and mutually amplify each other. The inflammasome, a key component of the innate immune system, plays an essential role in the development of vasculitis in KD. Thus, innate immune memory, or ‘trained immunity’, may promote vasculitis in KD. Hence, this review will be helpful in understanding the pathophysiologic pathways leading to the development of principal KD symptoms and coronary artery lesions in patients with KD, as well as in subsets of patients with SARS‐CoV‐2 and Yersinia infections.

COVID-19 and multisystem inflammatory syndrome in children and adolescents

As severe acute respiratory syndrome coronavirus 2 continues to spread worldwide, there have been increasing reports from Europe, North America, Asia, and Latin America describing children and adolescents with COVID-19-associated multisystem inflammatory conditions. However, the association between multisystem inflammatory syndrome in children and COVID-19 is still unknown. We review the epidemiology, causes, clinical features, and current treatment protocols for multisystem inflammatory syndrome in children and adolescents associated with COVID-19. We also discuss the possible underlying pathophysiological mechanisms for COVID-19-induced inflammatory processes, which can lead to organ damage in paediatric patients who are severely ill. These insights provide evidence for the need to develop a clear case definition and treatment protocol for this new condition and also shed light on future therapeutic interventions and the potential for vaccine development. TRANSLATIONS: For the French, Chinese, Arabic, Spanish and Russian translations of the abstract see Supplementary Materials section.

Low FCMR mRNA expression in leukocytes of patients with Kawasaki disease six months after disease onset

BACKGROUND

Immunoglobulin (Ig) M plays an important role in immune regulation. FCMR-encoded FcμR is a receptor of IgM. Previous research has suggested that IgM levels may be involved in the coronary artery lesions of Kawasaki syndrome or Kawasaki disease (KD). In this study, we aimed to explore the roles of mRNA expressions of IgM receptors, particularly FCMR, in KD patients. FCMR encodes the Fc fragment of immunoglobulin M receptor.

METHODS

We enrolled 60 KD patients and 55 non-KD controls. Whole-blood leukocytes were isolated, and the mRNA expression for FCMR was determined. Each mRNA consisted of a sample taken before intravenous immunoglobulin (IVIG) was administered (acute, KD1) and those taken at three weeks, six months, and one year later (KD3, KD4, KD5). Paired KD subjects were analyzed from both the acute and convalescent phases (n = 28).

RESULTS

After six months and one year of treatment, KD patients still apparently have lower FCMR compared with controls (P = .004). FCMR expressions were downregulated in male patients with KD prior to IVIG administration (P = .044). The FCMR of paired KD patients who received IVIG treatments after six months was significantly lower than before undergoing IVIG treatment (P = .044). Expressions in the polymorphonuclear leukocytes were similar to those in the peripheral blood mononuclear cells.

CONCLUSION

The unique data supported that FCMR is expressed by granulocytes at RNA levels in humans and demonstrated lower FCMR six months after the onset of KD. The findings remind us of the need to track the health of children with KD over the long term, even if we think patients have fully recovered.

Antibodies and Immunity During Kawasaki Disease

The cause of Kawasaki disease (KD), the leading cause of acquired heart disease in children, is currently unknown. Epidemiology studies support that an infectious disease is involved in at least starting the inflammatory cascade set off during KD. Clues from epidemiology support that humoral immunity can have a protective effect. However, the role of the immune system, particularly of B cells and antibodies, in pathogenesis of KD is still unclear. Intravenous immunoglobulin (IVIG) and other therapies targeted at modulating inflammation can prevent development of coronary aneurysms. A number of autoantibody responses have been reported in children with KD and antibodies have been generated from aneurysmal plasma cell infiltrates. Recent reports show that children with KD have similar plasmablast responses as other children with infectious diseases, further supporting an infectious starting point. As ongoing studies are attempting to identify the etiology of KD through study of antibody responses, we sought to review the role of humoral immunity in KD pathogenesis, treatment, and recovery.

Kawasaki disease: pathophysiology and insights from mouse models

Kawasaki disease is an acute febrile illness and systemic vasculitis of unknown aetiology that predominantly afflicts young children, causes coronary artery aneurysms and can result in long-term cardiovascular sequelae. Kawasaki disease is the leading cause of acquired heart disease among children in the USA. Coronary artery aneurysms develop in some untreated children with Kawasaki disease, leading to ischaemic heart disease and myocardial infarction. Although intravenous immunoglobulin (IVIG) treatment reduces the risk of development of coronary artery aneurysms, some children have IVIG-resistant Kawasaki disease and are at increased risk of developing coronary artery damage. In addition, the lack of specific diagnostic tests and biomarkers for Kawasaki disease make early diagnosis and treatment challenging. The use of experimental mouse models of Kawasaki disease vasculitis has considerably improved our understanding of the pathology of the disease and helped characterize the cellular and molecular immune mechanisms contributing to cardiovascular complications, in turn leading to the development of innovative therapeutic approaches. Here, we outline the pathophysiology of Kawasaki disease and summarize and discuss the progress gained from experimental mouse models and their potential therapeutic translation to human disease.

This Review outlines the pathophysiology of Kawasaki disease and discusses the progress gained from experimental mouse models and their potential therapeutic translation to human disease.

Kawasaki disease is a childhood systemic vasculitis leading to the development of coronary artery aneurysms; it is the leading cause of acquired heart disease in children in developed countries.

The cause of Kawasaki disease is unknown, although it is suspected to be triggered by an unidentified infectious pathogen in genetically predisposed children.

Kawasaki disease might not be a normal immune response to an unusual environmental stimulus, but rather a genetically determined unusual and uncontrolled immune response to a common stimulus.

Although the aetiological agent in humans is unknown, mouse models of Kawasaki disease vasculitis demonstrate similar pathological features and have substantially accelerated discoveries in the field.

Genetic and transcriptomic analysis of blood samples from patients with Kawasaki disease and experimental evidence generated using mouse models have demonstrated the critical role of IL-1β in the pathogenesis of this disease and the therapeutic potential of targeting this pathway (currently under investigation in clinical trials).

Coronary Vasculitis Induced in Mice by the Cell Wall Mannoprotein of Candida krusei

Kawasaki disease (KD) is an inflammatory disease that was identified by Professor Tomisaku Kawasaki in 1961. Candida albicans-derived substances, such as the hot water extract of C. albicans (CADS) and Candida water-soluble fraction (CAWS), induced coronary vasculitis similar to KD in mice. An increasing proportion of deep-seated candidiasis cases are caused by non-albicans Candida and are often resistant to antifungal drugs. We herein investigated whether the hot water extract of C. krusei, inherently resistant to fluconazole, induces vasculitis in mice. Three strains of C. krusei, NBRC1395, NBRC1162, and NBRC10737, were cultured in natural (Y) and chemically defined (C) media and cell wall mannoprotein (MN) fractions were prepared by autoclaving cells (CKY1395MN, CKC1395MN, CKY1162MN, CKC1162MN, CKY10737MN, and CKC10737MN). All MN fractions reacted strongly with Concanavalin A (Con A) and dectin-2 and induced anaphylactoid shock in ICR mice. MNs induced severe coronary vasculitis in DBA/2 mice, resulting in cardiac hypertrophy. MNs also induced coronary vasculitis in C57Bl/6 mice. These results suggest that the MNs of non-albicans Candida, such as C. krusei, induce similar toxicity to those of C. albicans.

Lower CMV and EBV Exposure in Children With Kawasaki Disease Suggests an Under-Challenged Immune System

Background: Kawasaki Disease (KD) is a pediatric vasculitis of which the pathogenesis is unclear. The hypothesis is that genetically pre-disposed children develop KD when they encounter a pathogen which remains most often unidentified or pathogen derived factors. Since age is a dominant factor, prior immune status in children could influence their reactivity and hence the acquisition of KD. We hypothesized that systemic immune responses early in life could protect against developing KD. With this study we tested whether the incidence of previous systemic cytomegalovirus (CMV) or Epstein-Barr virus (EBV) infection is lower in children with KD compared to healthy age-matched controls. Methods and Results: We compared 86 KD patients with an age-matched control group regarding CMV and EBV VCA IgG measurements (taken before or 9 months after IVIG treatment). We found that both CMV and EBV had an almost 2-fold lower seroprevalence in the KD population than in the control group. Conclusions: We suggest that an under-challenged immune system causes an altered immune reactivity which may affect the response to a pathological trigger causing KD in susceptible children.

Kawasaki Disease: The Role of Immune Complexes Revisited

Kawasaki disease (KD) is an inflammatory disease in children associated with vasculitis affecting predominantly the coronary arteries and is now the most common cause of acquired heart disease in children in developed countries. The etiology of KD is unknown but epidemiological studies implicate an infectious agent or toxin, which causes disease in genetically predisposed individuals. The presence of immune complexes (ICs) in the serum of children with KD was established in numerous studies during the 1970s and 80s. More recent genetic studies have identified variation in Fcγ receptors and genes controlling immunoglobulin production associated with KD. In this review we link the genetic findings and IC studies and suggest a key role for their interaction in pathophysiology of the disease.

B Cells and Antibodies in Kawasaki Disease

The etiology of Kawasaki disease (KD), the leading cause of acquired heart disease in children, is currently unknown. Epidemiology supports a relationship of KD to an infectious disease. Several pathological mechanisms are being considered, including a superantigen response, direct invasion by an infectious etiology or an autoimmune phenomenon. Treating affected patients with intravenous immunoglobulin is effective at reducing the rates of coronary aneurysms. However, the role of B cells and antibodies in KD pathogenesis remains unclear. Murine models are not clear on the role for B cells and antibodies in pathogenesis. Studies on rare aneurysm specimens reveal plasma cell infiltrates. Antibodies generated from these aneurysmal plasma cell infiltrates showed cross-reaction to intracellular inclusions in the bronchial epithelium of a number of pathologic specimens from children with KD. These antibodies have not defined an etiology. Notably, a number of autoantibody responses have been reported in children with KD. Recent studies show acute B cell responses are similar in children with KD compared to children with infections, lending further support of an infectious disease cause of KD. Here, we will review and discuss the inconsistencies in the literature in relation to B cell responses, specific antibodies, and a potential role for humoral immunity in KD pathogenesis or diagnosis.

[Research advances in the pathogenesis of familial Kawasaki disease]

Kawasaki disease has become the leading cause of acquired heart disease in children in North America and Japan. The incidence rate of Kawasaki disease varies significantly across regions and races. The first-degree relatives of patients with Kawasaki disease have a significantly higher risk of this disease than the general population. This article reviews the onset of familial Kawasaki disease and possible pathogenesis.

Preventing coronary artery lesions in Kawasaki disease

A form of systemic vasculitis that affects mostly small and medium-sized vessels, Kawasaki disease (KD) is most commonly found in children under the age of 5 years old. Though its etiology is unknown, KD has been the most frequent acquired heart disease in developing countries. Its incidence has increased over recent decades in many centuries, including Japan, Korea, and China. The most severe complications of KD are coronary artery lesions (CAL), including dilation, fistula, aneurysm, arterial remodeling, stenosis, and occlusion. Aneurysm formation has been observed in 20–25% of KD patients that do not receive intravenous immunoglobulin (IVIG) treatment, and in 3–5% that do receive it. Coronary artery dilation has been found in about 30% of KD patients in the acute stage, although mostly in the transient form. Diminishing the occurrence and regression of CAL is a vital part of treating KD. In this review article, I demonstrate the clinical method to prevent CAL formation used at the Kawasaki Disease Center in Taiwan.

Dissecting Kawasaki disease: a state-of-the-art review

Kawasaki disease (KD) is a pediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. The diagnosis is based on the presence of persistent fever and clinical features including exanthema, lymphadenopathy, conjunctival injection, and changes to the mucosae and extremities. Although the etiology remains unknown, the current consensus is that it is likely caused by an (infectious) trigger initiating an abnormal immune response in genetically predisposed children. Treatment consists of high dose intravenous immunoglobulin (IVIG) and is directed at preventing the development of CAA. Unfortunately, 10-20% of all patients fail to respond to IVIG and these children need additional anti-inflammatory treatment. Coronary artery lesions are diagnosed by echocardiography in the acute and subacute phases. Both absolute arterial diameters and z-scores, adjusted for height and weight, are used as criteria for CAA. Close monitoring of CAA is important as ischemic symptoms or myocardial infarction due to thrombosis or stenosis can occur. These complications are most likely to arise in the largest, so-called giant CAA. Apart from the presence of CAA, it is unclear whether KD causes an increased cardiovascular risk due to the vasculitis itself.

CONCLUSION

Many aspects of KD remain unknown, although there is growing knowledge on the etiology, treatment, and development and classification of CAA. Since children with previous KD are entering adulthood, long-term follow-up is increasingly important. What is known: • Kawasaki disease (KD) is a pediatric vasculitis with coronary artery damage as its main complication. • Although KD approaches its 50th birthday since its first description, many aspects of the disease remain poorly understood. What is new: • In recent years, multiple genetic candidate pathways involved in KD have been identified, with recently promising information about the ITPKC pathway. • As increasing numbers of KD patients are reaching adulthood, increasing information is available about the long-term consequences of coronary artery damage and broader cardiovascular risk.

Plasma Prostaglandin E2 Levels Correlated with the Prevention of Intravenous Immunoglobulin Resistance and Coronary Artery Lesions Formation via CD40L in Kawasaki Disease

BACKGROUND

A form of systemic vasculitis, Kawasaki disease (KD) occurs most frequently in children under the age of five years old. Previous studies have found that Prostaglandin E2 (PGE2) correlates with KD, although the related mechanisms are still unknown. CD40L may also be a marker of vasculitis in KD, so this study focuses on PGE2 and CD40L expression in KD.

MATERIALS AND METHODS

This study consisted of a total of 144 KD patients, whose intravenous immunoglobulin (IVIG)/coronary arterial lesion (CAL) formation resistance was evaluated. PGE2 levels were evaluated in vitro to study the effect of CD40L on CD4+ T lymphocytes.

RESULTS

PGE2 levels significantly increased after IVIG treatment (p<0.05), especially in patients who responded to initial IVIG treatment (p = 0.004) and for patients without CAL formation (p = 0.016). Furthermore, an in vitro study revealed that IVIG acted as a trigger for PGE2 expression in the acute-stage mononuclear cells of KD patients. According to our findings, both IVIG and PGE2 can impede surface CD40L expressions on CD4+ T lymphocytes (p<0.05).

CONCLUSIONS

The results of this study are among the first to find that plasma PGE2 is correlated with the prevention of IVIG resistance and CAL formation through CD40L in KD.

Development of a highly resolutive method, using a double quadruplex tetra-primer-ARMS-PCR coupled with capillary electrophoresis to study CD40LG polymorphisms

Polymorphisms in the CD40 ligand gene (CD40LG) are associated with various immunological disorders such as tumors, autoimmune and infectious diseases. The aim of this study was to develop a highly optimized double quadruplex tetra-primer amplification refractory mutation system PCR (double quadruplex T-ARMS-PCR) coupled with capillary electrophoresis to allow genotyping of eight relevant candidate CD40LG SNPs and to establish haplotypes. After conducting the double quadruplex T-ARMS-PCR, the genotypes obtained through agarose electrophoresis were compared with those obtained through capillary electrophoresis. This strategy was applied to analyze the genetic patterns of CD40LG in two distinct cohorts of blood donors (211 French and 274 Tunisian). The T-ARMS-PCR method was rapid, inexpensive, reproducible and reliable for SNP determination. Regarding the separation technique, capillary electrophoresis allows traceable and semi-automated analysis while agarose electrophoresis remains a cost-effective technique that does not require specialized or costly equipment. Using these methods, we identified significantly different genetic heterogeneity between the two investigated populations (p ≤ 0.0001) and we also extensively characterized their haplotypes. The obtained genotype distribution and the optimized quadruplex T-ARMS-PCR technique coupled with capillary electrophoresis provides valuable information for studying pathologic inflammation leading to various diseases in which CD40LG might be a candidate gene.

Identification of an association between genomic hypomethylation of FCGR2A and susceptibility to Kawasaki disease and intravenous immunoglobulin resistance by DNA methylation array

OBJECTIVE

Kawasaki disease (KD) is characterized by systemic vasculitis, and it is the most common acquired heart disease in children. However, the etiology and immunopathogenesis of KD are still unclear. A genome-wide association study (GWAS) identified polymorphisms in CD40, BLK, and FCGR2A as the susceptibility genes for KD. No epigenetic array studies of KD have previously been published. This study was undertaken to investigate differences in DNA methylation in patients with KD as compared to controls.

METHODS

The HumanMethylation27 BeadChip (Illumina) was used to survey the differences in DNA methylation between KD patients and controls. DNA methylation array validation was performed in a separate cohort by pyrosequencing assay and reporter gene assays. Messenger RNA (mRNA) expression was determined, and the association of methylation with response to intravenous immunoglobulin (IVIG) treatment was analyzed.

RESULTS

HumanMethylation27 BeadChip assay showed a 15% difference in methylation of 10 genes between KD patients and controls. The FCGR2A cg24422489 group, which was recently reported to be associated with KD susceptibility in a GWAS, had significant hypomethylation of 15.54% less in the KD group than in the control group. Validation of FCGR2A methylation in another cohort also showed significant hypomethylation in the KD group (5 of 5 CpG sites [P < 0.01]; n = 43 in the KD group and n = 55 in the control group). KD patients with IVIG resistance showed hypomethylation of 5 CpG sites (P < 0.05). FCGR2A mRNA expression was significantly increased in patients in the acute stage of KD compared to controls. Reporter gene assays indicated that the CpG sites of the FCGR2A promoter region were sufficient to modulate gene expression.

CONCLUSION

This is the first study to examine the DNA methylation array in KD and identify a role of hypomethylation of FCGR2A in susceptibility to KD and IVIG resistance.

Intravenous immunoglobulin, pharmacogenomics, and Kawasaki disease

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology and it is therefore worth examining the multifactorial interaction of genes and environmental factors. Targeted genetic association and genome-wide association studies have helped to provide a better understanding of KD from infection to the immune-related response. Findings in the past decade have contributed to a major breakthrough in the genetics of KD, with the identification of several genomic regions linked to the pathogenesis of KD, including ITPKC, CD40, BLK, and FCGR2A. This review focuses on the factors associated with the genetic polymorphisms of KD and the pharmacogenomics of the response to treatment in patients with intravenous immunoglobulin resistance.

The roles of Ca2+/NFAT signaling genes in Kawasaki disease: single- and multiple-risk genetic variants

Ca²⁺/nuclear factor of activated T-cells (Ca²⁺/NFAT) signaling pathway may play a crucial role in Kawasaki disease (KD). We investigated 16 genetic variants, selected by bioinformatics analyses or previous studies, in 7 key genes involved in this pathway in a Chinese population. We observed a significantly or marginally increased KD risk associated with rs2720378 GC + CC genotypes (OR = 1.39, 95% CI = 1.07–1.80, P = 0.014) or rs2069762 AC + CC genotypes (OR = 1.28, 95% CI = 0.98–1.67, P = 0.066), compared with their wild type counterparts. In classification and regression tree analysis, individuals carrying the combined genotypes of rs2720378 GC or CC genotype, rs2069762 CA or CC genotype and rs1561876 AA genotype exhibited the highest KD risk (OR = 2.12, 95% CI = 1.46–3.07, P < 0.001), compared with the lowest risk carriers of rs2720378 GG genotype. Moreover, a significant dose effect was observed among these three variants (P_trend < 0.001). In conclusion, this study implicates that single- and multiple-risk genetic variants in this pathway might contribute to KD susceptibility. Further studies on more comprehensive single nucleotide polymorphisms, different ethnicities and larger sample sizes are warranted, and the exact biological mechanisms need to be further clarified.

Evidence for involvement of the CD40/CD40L system in post-stroke epilepsy

Post-stroke epilepsy (PSE) has a negative effect on stroke prognosis and quality of life. The CD40/CD40L system is reported to be involved in the progression of multiple disease states. We investigated the association between functional polymorphism of CD40 and PSE susceptibility, and we also explored the role of the CD40/CD40L system in PSE. A case-control study was performed in 410 ischemic stroke (IS) patients and in 389 PSE patients. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The CD40 mRNA and protein levels were determined by real-time PCR and western blotting, respectively. The plasma sCD40L level was detected using an ELISA kit. The frequency of the T allele in PSE patients was significantly higher than in IS patients (P<0.05). The plasma sCD40L level was significantly higher in the PSE patients than in the healthy controls and IS patients (P<0.01, P<0.05, respectively). The peripheral blood mononuclear cells (PBMCs) from PSE patients showed significantly higher CD40 mRNA and protein expression than the healthy controls and IS patients (P<0.01, P<0.05, respectively). In the PSE patients, the T-allele carriers showed increased plasma sCD40L levels and increased CD40 mRNA expression. Our study suggested that the T allele of the CD40 -1C/T polymorphism may be associated with PSE susceptibility. The CD40/CD40L system is involved in the process of PSE.

The role of infection in Kawasaki syndrome

OBJECTIVES

To analyse the evidence suggesting a possible infectious origin of Kawasaki syndrome (KS).

METHODS

PubMed was searched for all of the studies published over the last 15 years using the key words "Kawasaki syndrome" or "mucocutaneous lymph node syndrome" and "infectious disease" or "genetics" or "vasculitis" or "pathogenesis".

RESULTS

Various levels of evidence support the hypothesis that KS is a complex disease triggered by an infection due to one or more pathogens. Viruses or bacteria may be the primum movens, although no specific infectious agent can be considered definitely etiological. A number of genetic polymorphisms have been identified in subjects with KS, but none of them can currently be considered a real marker of susceptibility.

CONCLUSIONS

Various data suggest that KS is intimately related to infectious diseases and that its clinical expression is influenced by predisposing genetic backgrounds, but our knowledge of the infectious agent(s) involved and the genetic characteristics of susceptible children remains only partial. Further studies are needed to address the many still open questions concerning the disease.

Understanding the pathogenesis of Kawasaki disease by network and pathway analysis

Kawasaki disease (KD) is a complex disease, leading to the damage of multisystems. The pathogen that triggers this sophisticated disease is still unknown since it was first reported in 1967. To increase our knowledge on the effects of genes in KD, we extracted statistically significant genes so far associated with this mysterious illness from candidate gene studies and genome-wide association studies. These genes contributed to susceptibility to KD, coronary artery lesions, resistance to initial IVIG treatment, incomplete KD, and so on. Gene ontology category and pathways were analyzed for relationships among these statistically significant genes. These genes were represented in a variety of functional categories, including immune response, inflammatory response, and cellular calcium ion homeostasis. They were mainly enriched in the pathway of immune response. We further highlighted the compelling immune pathway of NF-AT signal and leukocyte interactions combined with another transcription factor NF- κ B in the pathogenesis of KD. STRING analysis, a network analysis focusing on protein interactions, validated close contact between these genes and implied the importance of this pathway. This data will contribute to understanding pathogenesis of KD.

Molecular diagnosis of genodermatoses

The progress of molecular genetics helps clinicians to prove or exclude a suspected diagnosis for a vast and yet increasing number of genodermatoses. This leads to precise genetic counselling, prenatal diagnosis and preimplantation genetic haplotyping for many inherited skin conditions. It is also helpful in such occasions as phenocopy, late onset and incomplete penetrance, uniparental disomy, mitochondrial inheritance and pigmentary mosaicism. Molecular methods of two genodermatoses are explained in detail, i.e. genodermatoses with skin fragility and neurofibromatosis type 1.

CD40 Gene polymorphisms associated with susceptibility and coronary artery lesions of Kawasaki disease in the Taiwanese population

BACKGROUND

Kawasaki disease (KD) is characterized by systemic vasculitis of unknown etiology. Our previous studies showed expression of CD40 ligand on CD4+ T cells correlated to the coronary artery lesion (CAL) and disease progress in KD. Other studies from Japan suggested the role of CD40L in the pathogenesis of CAL, and this might help explain the excessive number of males affected with KD but cannot be reproduced by Taiwanese population. This study was conducted to investigate the CD40 polymorphism in KD and CAL formation.

METHODS

A total of 950 subjects (381 KD patients and 569 controls) were investigated to identify 2 tagging single-nucleotide polymorphisms (tSNPs) of CD40 (rs4810485 and rs1535045) by using the TaqMan allelic discrimination assay.

RESULTS

A significant association was noted with regards to CD40 tSNPs (rs1535045) between controls and KD patients (P = 0.0405, dominant model). In KD patients, polymorphisms of CD40 (rs4810485) showed significant association with CAL formation (P = 0.0436, recessive model). Haplotype analysis did not yield more significant results between polymorphisms of CD40 and susceptibility/disease activity of KD.

CONCLUSIONS

This study showed for the first time that polymorphisms of CD40 are associated with susceptibility to KD and CAL formation, in the Taiwanese population.

Pathogénie de la maladie de Kawasaki : quoi de neuf ?

La maladie de Kawasaki (MK) est une vascularite inflammatoire aiguë survenant le plus souvent chez le nourrisson et dont le pronostic est dicté par l’atteinte coronarienne. La cause de cette maladie reste inconnue mais différentes hypothèses ont été développées ces dernières années et s’associent à des travaux de recherche pour la compréhension de la physiopathologie de la MK. La présentation clinique de la MK partage de nombreux signes avec des maladies infectieuses virales et bactériennes. La possibilité d’une maladie infectieuse à superantigène a été suggérée. La fréquence augmentée dans certaines populations, la survenue précoce à l’âge pédiatrique supporte la participation de facteurs génétiques dans le développement de la maladie. Certaines anomalies immunologiques sont également retrouvées chez les sujets présentant une MK, suggérant qu’un déséquilibre immunologique est à l’origine de la vascularite.

Polymorphisms of transforming growth factor-β signaling pathway and Kawasaki disease in the Taiwanese population

Kawasaki disease (KD) is a systemic vasculitis associated with cardiovascular symptom. A previous study in the European descent has indicated that genetic variants of the transforming growth factor-β (TGF-β) pathway are involved in the KD susceptibility and clinical status. This study was conducted to investigate if polymorphisms in TGF-β signaling pathway are associated with KD susceptibility, and the coronary artery lesion formation. A total of 950 subjects (381 KD patients and 569 controls) were investigated to identify 12 single-nucleotide polymorphisms in the TGF-β signaling pathway (rs2796817, rs10482751, rs2027567, rs12029576, rs11466480, rs4776338, rs12901071, rs7162912, rs1438386, rs6494633, rs12910698 and rs4776339) by using TaqMan Allelic Discrimination assay. Our results indicated that rs1438386 in the SMAD3 is significantly associated with the susceptibility of KD. Additionally, both haplotypes of TGFβ2 and SMAD3 were also associated with the risk of KD. This study showed that genetic polymorphisms in TGF-β signaling pathway are associated with KD susceptibility, but not coronary artery lesions formation, or intravenous immunoglobulin treatment response in the Taiwanese population.

Genetic polymorphisms in Kawasaki disease

Kawasaki disease (KD) is an acute febrile systemic vasculitis, and the cause of KD is not well understood. It is likely due to multiple interactions between genes and environmental factors. The development of genetic association and genome-wide association studies (GWAS) has opened an avenue to better understanding the molecular mechanisms underlying KD. A novel ITPKC signaling pathway was recently found to be responsible for the susceptibility to KD. Furthermore, the GWAS demonstrated the functionally related susceptibility loci for KD in the Caucasian population. In the last decade, the identification of several genomic regions linked to the pathogenesis of KD has made a major breakthrough in understanding the genetics of KD. This review will focus on genetic polymorphisms associated with KD and describe some of the possible clinical implications and molecular mechanisms that can be used to explain how genetic variants regulate the pathogenesis in KD.

Clinical Implication of the C Allele of the ITPKC Gene SNP rs28493229 in Kawasaki Disease: Association With Disease Susceptibility and BCG Scar Reactivation

BACKGROUND

a functional single nucleotide polymorphism (SNP) (rs28493229) in the inositol 1,4,5-trisphosphate 3-kinase C (ITPKC) gene has been linked to the susceptibility to Kawasaki disease (KD). The implication remains unclear.

SUBJECTS AND METHODS

genotyping for the ITPKC polymorphism was conducted on 280 unrelated Taiwanese children with KD and 492 healthy ethnically and gender-matched controls. The clinical manifestations and laboratory data were systemically collected.

RESULTS

the GC and CC genotypes of ITPKC gene SNP rs28493229 were overrepresented in KD patients (GG:GC:CC was 236:43:1, C allele frequency: 8.04%) than those in the controls (GG:GC:CC was 454:37:1, C allele frequency: 3.96%; OR: 2.23, P = 0.001). In KD patients, those with GC or CC genotypes of SNP rs28493229 (19/44) were more likely to have reactivation at the Bacille Calmette-Guérin (BCG) inoculation site than those with GG genotypes (66/236; OR: 1.96, P = 0.044). Such association was particularly strong in patients aged <20 months (OR: 3.26, P = 0.017). The other clinical manifestations were not related to this SNP. There were 160 (57.1%) patients with coronary arterial lesions. The development and the severity of coronary arterial lesion were also not associated with this SNP. Comparison between patients with and without BCG reactivation revealed only one difference: patients with reactivation were younger.

CONCLUSION

in a cohort from a population with the world's third highest incidence of KD, we demonstrated that the C-allele of ITPKC SNP rs28493229 is associated with KD susceptibility and BCG scar reactivation during the acute phase, although its frequency is lower than that in the Japanese cohort (22.6%), suggesting this SNP contributes to KD susceptibility through induced hyperimmune function reflected in the BCG reactivation.

Kawasaki disease: update on pathogenesis

PURPOSE OF REVIEW

This review will highlight recent advances in our understanding of the pathogenesis of Kawasaki disease, highlighting the molecular players involved in regulation of T-cell activation and their affect on disease incidence and outcome in both humans and mouse.

RECENT FINDINGS

Kawasaki disease is the most common cause of multisystem vasculitis in childhood. The vessels most commonly damaged are the coronary arteries, making Kawasaki disease the number one cause of acquired heart disease in children from the developed world. The contribution of genetics to disease predisposition is clearly implicated, but the mechanisms involved in regulating predisposition to disease susceptibility and outcome are not clearly understood. Two independent approaches have recently identified regulation of T-cell activation as the critical factor in determining susceptibility and severity of Kawasaki disease. Firstly, genetic analysis of affected Japanese children identified ITPKC, 1,4,5-triphosphate 3-kinase C, a kinase involved in regulation of T-cell activation, to be significantly associated with susceptibility to and increased severity of Kawasaki disease. A second independent approach using an animal model of Kawasaki disease has also identified regulation of T-cell activation, specifically costimulation, the second signal regulating optimal T-cell activation as the critical regulator of susceptibility to and severity of disease.

SUMMARY

Understanding the molecular players responsible for dysregulation of the immune response in Kawasaki disease will foster development of improved diagnostic/predictive tools and more rational use of therapeutic agents to improve outcome in affected children.

The role of protozoa-driven selection in shaping human genetic variability

Protozoa exert a strong selective pressure in humans. The selection signatures left by these pathogens can be exploited to identify genetic modulators of infection susceptibility. We show that protozoa diversity in different geographic locations is a good measure of protozoa-driven selective pressure; protozoa diversity captured selection signatures at known malaria resistance loci and identified several selected single nucleotide polymorphisms in immune and hemolytic anemia genes. A genome-wide search enabled us to identify 5180 variants mapping to 1145 genes that are subjected to protozoa-driven selective pressure. We provide a genome-wide estimate of protozoa-driven selective pressure and identify candidate susceptibility genes for protozoa-borne diseases.

Progress in pediatric vasculitis

PURPOSE OF REVIEW

To examine recent advances in the pathophysiology and therapy of pediatric vasculitis.

RECENT FINDINGS

The past 2 years have been marked by significant progress in extending novel techniques to the investigation of the two most common pediatric vasculitis syndromes, Henoch-Schonlein purpura and Kawasaki disease. Study of other vasculitides, such as Wegener granulomatosis, Churg-Strauss syndrome, and microscopic polyangiitis, is impeded by the small number of pediatric patients. Nonetheless, national and international registries are beginning to provide the foundation for generation of testable hypotheses regarding pathogenesis and optimal treatment. Thus, recent data from the study of children suggest that disorders in the control of inflammation, such as those that underlie familial Mediterranean fever and other autoinflammatory diseases, may predispose to vasculitis. Improved knowledge of mechanisms of disease, in turn, should pave the way for more targeted, effective, and tolerable therapies for children with systemic vasculitis.

SUMMARY

International collaboration to study rare disorders such as pediatric vasculitis are demonstrating disorders of inflammatory regulation that predispose to these diseases and may point toward new treatment approaches.

Molecular genetics of Kawasaki disease

Kawasaki disease (KD) is a leading cause of acquired cardiac disease of children in the developed countries. The pathogen that triggers this perplexing disease is still unknown after 40 y from the first description. Epidemiologic findings have made us believe that there are considerable genetic components in the etiology and some candidate genetic variations, which confer susceptibility to KD or risk for coronary artery lesions have been identified. However, most of them remain to be definitively confirmed by replication studies with large cohorts. In this article, I review the candidate gene association studies to date. I also introduce our recent findings in genome-wide approach, which revealed the importance of Ca2+/nuclear factor of activated T-cells pathway in the pathogenesis of KD.

Genetic polymorphisms in the CD40 ligand gene and Kawasaki disease

BACKGROUND

Although some previous studies have reported that genetic and immunological factors play important roles in the pathogenesis of Kawasaki disease (KD), the etiological factors of this enigmatical pediatric disease are still poorly understood.

PURPOSE

This study aims to investigate whether polymorphisms of the CD40 ligand (CD40L) gene are associated with KD and the development of coronary artery lesions (CAL) in the Taiwanese children.

MATERIALS AND METHODS

The CD40L -3459 A/G and IVS4+121 A/G single nucleotide polymorphisms (SNPs) were genotyped in 167 children with KD and 1,010 ethnically matched healthy controls by TaqMan assay.

RESULTS

None of the CD40L polymorphisms was associated with susceptibility or CAL development of KD, and this finding was supported by the haplotype analysis.

CONCLUSION

In summary, these results provide little support for specific CD40L SNPs in the susceptibility or CAL development of KD in Taiwanese children. However, it will be necessary to validate or replicate this association in other independent large-size ethnic groups.

Genetic Variations of HLA-DRB1 and Susceptibility to Kawasaki Disease in Taiwanese Children

Although some previous studies have reported that genetic and immunologic factors play important roles in the pathogenesis of Kawasaki disease (KD), the etiologic factors of this enigmatic pediatric disease are still poorly understood. The purpose of this study was to investigate whether polymorphisms of the human leukocyte antigen DRB1 (HLA-DRB1) gene are associated with KD and the development of coronary artery lesions (CAL) in Taiwanese children. Genomic DNA was extracted from whole blood samples from 145 children with KD and 331 healthy controls. The HLA-DRB1 gene was genotyped by polymerase chain reaction (PCR) and sequence-based typing assays. We found that the distribution of HLA-DRB1 allele families and alleles in children with KD did not differ from that in healthy controls. Stratified analysis did not demonstrate any association between particular HLA-DRB1 allele families or alleles and the development of CAL in children with KD. These findings suggest that susceptibility to KD and CAL is not associated with the HLA-DRB1 gene in a Taiwanese population. If immunogenetic determinants are involved in this disease and its complications in Taiwanese children, they must involve genes other than HLA-DRB1.

Epidemiology and etiology of Kawasaki disease

Kawasaki disease was first reported in Japan in 1967 by Dr. Tomisaku Kawasaki. It has since been recognized worldwide, and in at the United States and Japan is the most important cause of acquired heart disease in children, surpassing other more recognized conditions such as rheumatic fever, endocarditis and myocarditis. It is primarily a disease of children less than 5 years of age but has been reported in older children and adults. Risk factors for the illness include Asian ancestry, male gender and certain familial predispositions. Observations such as similarity to certain exanthematous infectious diseases, temporal-geographic clustering of cases and seasonality in incidence favors an infectious etiology. Pathology and pathogenesis of the disease indicate that it is a medium-sized artery vasculitis that results from a dramatic immune activation that in most cases reversed by immune modulating agents such as intravenous immunoglobulin. Unfortunately, the etiology of the illness remains obscure, although recent studies favor a possible viral etiology.

A genomewide linkage analysis of Kawasaki disease: evidence for linkage to chromosome 12

Kawasaki disease (KD) is an acute systemic vasculitis syndrome that primarily affects infants and young children. The cause of KD is largely unknown, but its higher incidence in the Asian population and increased risk in patients' families suggests the existence of underlying genetic factors. To determine the loci of a susceptibility gene for KD, a genomewide linkage analysis with affected sib pairs was performed on 78 family samples collected from all over Japan. Multipoint linkage analysis using MAPMAKER/SIBS 2.0 identified evidence of linkage on 12q24 [maximum lod score (MLS) = 2.69]. Possible linkage (MLS > 1.0) was also found on 4q35, 5q34, 6q27, 7p15, 8q24, 18q23, 19q13, Xp22, and Xq27. This is the first large-scale study of the genetic susceptibility to KD, and our results, combined with the accumulated knowledge of the human genome, could greatly promote research on identification of the molecular pathogenesis of KD.

Family-based association analysis implicates IL-4 in susceptibility to Kawasaki disease

Several compelling lines of evidence suggest an important influence of genetic variation in susceptibility to Kawasaki disease (KD), an acute vasculitis that causes coronary artery aneurysms in children. We performed a family-based genotyping study to test for association between KD and 58 genes involved in cardiovascular disease and inflammation. By analysis of a cohort of 209 KD trios using the transmission disequilibrium test, we documented the asymmetric transmission of five alleles including the interleukin-4 (IL-4) C(-589)T allele (P=0.03). Asymmetric transmission of the IL-4 C(-589)T was replicated in a second, independent cohort of 60 trios (P=0.05, combined P=0.002). Haplotypes of alleles in IL-4, colony-stimulating factor 2 (CSF2), IL-13, and transcription factor 7 (TCF7), all located in the interleukin gene cluster on 5q31, were also asymmetrically transmitted. The reported associations of KD with atopic dermatitis and allergy, elevated serum IgE levels, eosinophilia, and increased circulating numbers of monocyte/macrophages expressing the low-affinity IgE receptor (FCepsilonR2) may be related to effects of IL-4. Thus, the largest family-based genotyping study of KD patients to date suggests that genetic variation in the IL-4 gene, or regions linked to IL-4, plays an important role in KD pathogenesis and disease susceptibility.

Update on pediatric vasculitis

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of the recent research and progress made in the field of pediatric vasculitis.

RECENT FINDINGS

Over the past year, researchers have described several polymorphisms in Henoch-Schonlein purpura and Kawasaki Disease as well as the association between various vasculitides and infections. International and multidisciplinary efforts in Kawasaki Disease have resulted in recommendations for its diagnosis, treatment, and long-term management to improve patient care and further increase global collaboration. Researchers are investigating the role of inflammation and its role in endothelial health and atherosclerosis. Treatment regimens continue to improve, with the use of different immunosuppressive medications; however, we continue to have incomplete treatment successes.

SUMMARY

Vasculitides are rare conditions with significant morbidity and mortality whose prognosis has improved with newer diagnostic modalities and treatments; however, we continue to have insufficient knowledge of vasculitides and lack unambiguous diagnostic criteria. As technology continues to progress it is clear that a single cause of these diseases may be an oversimplification: the genetic makeup of individuals, as well as various environmental exposures, are of vital importance in the pathophysiology and evolution of disease processes, as well as response to therapy. Efforts should continue to improve international multicenter collaboration and interdisciplinary efforts to help solve this ever-growing puzzle.

Kawasaki disease: infection, immunity and genetics

Kawasaki disease is an acute multisystem vasculitic syndrome of unknown etiology occurring mostly in infants and children younger than 5 years of age. In developed countries, Kawasaki disease is currently the leading cause of acquired heart diseases in children. However, it is still a mysterious disease. In this article, we reviewed and summarized from the aspects based on infection agents, host immune dysregulation and genetic background intended to establish a feasible infection-immunogenetic pathogenesis for this mysterious disease and also provided the rational strategy to explore optimal treatment of this disease.

Current perspectives on Kawasaki disease

The etiology of Kawasaki disease (KD) remains unknown despite several years of dedicated research in this direction. Recently coronavirus infection and genetic polymorphisms have been implicated. Since first description of the disease there have been few changes in the diagnostic criteria except for newer recommendations of fever of at least 4 instead of 5 days duration. Recently, Echocardiography Criteria and Laboratory Criteria have been added to aid in the diagnosis of incomplete KD where all the historical diagnostic criteria are not present; this is now called the "incomplete form of KD" as opposed to "atypical form of KD". The word "atypical" is reserved for unusual presentations of KD such as those with hemophagocytic syndrome or nerve palsy. The treatment of KD includes infusion of high dose immunoglobulin. Patients non-responsive to immunoglobulin therapy are labeled as having "immunoglobulin resistant KD". The treatment of immunoglobulin resistant KD can be challenging and new therapies that have tried with some success. Late outcomes after 4 decades of treating these patients have recently been published. There has been some concern about increased risk for premature atherosclerosis in patients with childhood KD who had coronary artery abnormalities.