Two new susceptibility loci for Kawasaki disease identified through genome-wide association analysis

The changes of coagulation profiles in Kawasaki disease and its associations with clinical classification, intravenous immunoglobulin responsiveness and coronary artery involvement

Coagulation disorders are common in Kawasaki disease (KD). The main objectives of the present study were to probe the associations of coagulation profiles with clinical classification, IVIG responsiveness, coronary artery abnormalities (CAAs) in the acute episode of KD. A total of 313 KD children were recruited and divided into six subgroups, including complete KD (n = 217), incomplete KD (n = 96), IVIG-responsive KD (n = 293), IVIG-nonresponsive KD (n = 20), coronary artery noninvolvement KD (n = 284) and coronary artery involvement KD (n = 29). Blood samples were collected within 24-h pre-IVIG therapy and 48-h post-IVIG therapy. Coagulation profiles, conventional inflammatory mediators and blood cell counts were detected. Echocardiography was performed during the period from 2- to 14-day post-IVIG infusion. In addition, 315 sex- and age-matched healthy children were enrolled as the controls. (1) Before IVIG therapy, coagulation disorders were more prone to appear in KD patients than in healthy controls, and could be overcome by IVIG therapy. FIB and DD significantly increased in the acute phase of KD, whereas reduced to normal levels after IVIG therapy. (2) PT and APTT were significantly longer in patients with complete KD when compared with their incomplete counterparts after IVIG therapy. (3) The larger δDD, δFDP and the smaller δPT, δINR predicted IVIG nonresponsiveness. (4) The higher δDD and δFDP correlated with a higher risk for CAAs (DD: r = -0.72, FDP: r = -0.54). Coagulation disorders are correlated with complete phenotype, IVIG nonresponsiveness and CAA occurrence in the acute episode of KD, and can be rectified by synergistic effects of IVIG and aspirin.

Genetics of vasculitis

Systemic vasculitis encompasses a wide range of conditions characterized by varying degrees of inflammation in blood vessels. Although the etiology of vasculitis remains unclear, accumulated data suggest that it is triggered in genetically predisposed individuals by the concurrence of certain environmental factors. The importance of the genetic component has been consistently supported by evidence of familial aggregation, differential prevalence by ethnicity, and multiple genetic associations with disease susceptibility and severity reported in recent years. The strongest association signals in most vasculitides correspond to genetic variants within the HLA region, suggesting an important role of the immune system in its pathophysiology. However, each type of vasculitis has distinct defining HLA association markers, likely due to disease-specific differences in antigenic drivers. Furthermore, other genetic polymorphisms located outside the HLA region play an important role in susceptibility to different vasculitides. More recent research has assessed the shared genetic susceptibility evident across different vasculitides. Future studies should focus on the identification of genetic markers that can serve as reliable biomarkers for early diagnosis, prognosis, and treatment response in systemic vasculitis.

Secular trend of Kawasaki disease and its correlation with viral activity in Taiwan: a nationwide population-based study

BACKGROUND

Kawasaki disease (KD) is the most important acquired heart disease in children. This study investigated annual incidence, seasonality, secular trend and the correlation of KD incidence with viral activity in Taiwan.

METHODS

Through the national health insurance database, we identified KD during 2001-2020. The viral activity was obtained from nationwide surveillance database. We analyzed KD age-specific annual incidence, secular trends, seasonality and the correlation between KD incidence and common enteric or respiratory viral activity.

RESULTS

The KD incidence of subjects younger than 18 years significantly increased from 2001 to 2020 (11.78 and 22.40 per 100,000 person-years, respectively), and substantially decreased with age. Infants younger than 1 year presented the highest KD annual incidence at 105.82 to 164.34 per 100,000 person-years from 2001 to 2020. For all KD patients, the most frequently occurring season was summer followed by autumn. The KD incidence of infants younger than 1 year had significantly positive correlation with enteric (r = 0.14) and respiratory (r = 0.18) viral activity.

CONCLUSIONS

This study demonstrates the increasing trend of KD annual incidence and seasonality (more in summer and autumn) in Taiwan. The activity of common respiratory and enteric viruses was significantly correlated with KD incidence in infants.

Association between maternal heavy metal exposure and Kawasaki Disease, the Japan Environment and Children's Study (JECS)

Kawasaki disease (KD) is an acute systemic vasculitis primarily affecting young children, with an unclear etiology. We investigated the link between maternal heavy metal exposure and KD incidence in children using the Japan Environment and Children's Study, a large-scale nationwide prospective cohort with approximately 100,000 mother-child pairs. Maternal blood samples collected during the second/third trimester were analyzed for heavy metals [mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se), manganese (Mn)], divided into four quartiles based on concentration levels. KD incidence within the first year of life was tracked via questionnaire. Among 85,378 mother-child pairs, 316 children (0.37%) under one year were diagnosed with KD. Compared with the lowest concentration group (Q1), the highest (Q4) showed odds ratios (95% confidence interval) for Hg, 1.29 (0.82-2.03); Cd, 0.99 (0.63-1.58); Pb, 0.84 (0.52-1.34); Se, 1.17 (0.70-1.94); Mn, 0.70 (0.44-1.11), indicating no concentration-dependent increase. Sensitivity analyses with logarithmic transformation and extended outcomes up to age 3 yielded similar results. No significant association was found between maternal heavy metal levels and KD incidence, suggesting that heavy metal exposure does not increase KD risk.

2024 Heart Disease and Stroke Statistics: A Report of US and Global Data From the American Heart Association

BACKGROUND

The American Heart Association (AHA), in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, nutrition, sleep, and obesity) and health factors (cholesterol, blood pressure, glucose control, and metabolic syndrome) that contribute to cardiovascular health. The AHA Heart Disease and Stroke Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, brain health, complications of pregnancy, kidney disease, congenital heart disease, rhythm disorders, sudden cardiac arrest, subclinical atherosclerosis, coronary heart disease, cardiomyopathy, heart failure, valvular disease, venous thromboembolism, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The AHA, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States and globally to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2024 AHA Statistical Update is the product of a full year's worth of effort in 2023 by dedicated volunteer clinicians and scientists, committed government professionals, and AHA staff members. The AHA strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional global data, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Viral load of Torquetenovirus correlates with Sano's score and levels of total bilirubin and aspartate aminotransferase in Kawasaki disease

Cause of Kawasaki disease (KD) is unknown. KD is often resistant to treatment with intravenous immunoglobulin (IVIG). Sano's score, which is derived from total bilirubin (TBIL), aspartate aminotransferase (AST) and C-reactive protein (CRP), is predictive of IVIG resistance in Japan. A recent study reported that Torquetenovirus (TTV), especially TTV7, was present at a high viral load in the patients with KD. We used PCR to quantify TTV load and amplicon next generation sequencing to detect individual TTV species. We used serum samples that were collected between 2002 and 2005 from 57 Japanese KD patients before IVIG treatment. Correlations between TTV load and Sano's score, the biomarkers that constitute this score, and IVIG resistance were examined. TTV load was positively correlated with Sano's score (P = 0.0248), TBIL (P = 0.0004), and AST (P = 0.0385), but not with CRP (P = 0.6178). TTV load was marginally correlated with IVIG resistance (P = 0.1544). Presence of TTV7 was correlated with total TTV load significantly (P = 0.0231). The correlations between biomarkers for KD and TTV load suggested that TTV may play a role in the pathophysiology of KD. We hypothesize that TTV7 may be associated with a higher total viral load in KD.

Identification of B-cell-related HSPG2 and CDSN as susceptibility loci for Kawasaki disease

Kawasaki disease (KD) is an acute pediatric vasculitis that predominantly affects children under the age of 5 years. To date, genome-wide association studies (GWAS) have identified several KD susceptibility genes (e.g., BLK, CD40, FCGR2A, BCL2L11, and IGHV), which are mainly involved in B cell immunity. In this study, we aimed to identify additional KD susceptibility genes mainly involved in B cell development and functions by analyzing our previous GWAS data and conducting a replication study using new sample. Initially, we selected 30 single nucleotide polymorphisms (SNPs) in B-cell-related genes that were significantly (P < 0.01) associated with KD in our previous GWAS analysis of 247 KD cases with complete type and 1,000 healthy controls. Replication study was performed by genotyping the new 837 KD case samples with Fluidigm system and comparing them with 3,553 control genotypes. Among the 30 candidate SNPs, two were significantly associated with KD (P < 0.001) in the replication study. An even greater association between these SNPs and KD was observed in the combined analysis of GWAS and replication samples: odds ratio (OR) = 1.97 (P = 8.61 × 10-6) for rs2270699 (nonsynonymous SNP: c.10588C > T, p.Arg3530Trp) in the heparan sulfate proteoglycan 2 (HSPG2) gene and OR = 1.28 (P = 1.34 × 10-6) for rs3130992 (intronic SNP) in both the corneodesmosin (CDSN) and psoriasis susceptibility 1 candidate 1 (PSORS1C1) genes. These results suggest that the B-cell-related genes, HSPG2 and CDSN or PSORS1C1, play a role in the development of KD.

Whole-exome sequencing analysis identifies novel variants associated with Kawasaki disease susceptibility

BACKGROUND

Kawasaki disease (KD) is an acute pediatric vasculitis affecting genetically susceptible infants and children. Although the pathogenesis of KD remains unclear, growing evidence links genetic susceptibility to the disease.

METHODS

To explore the genes associated with susceptibility in KD, we applied whole-exome sequencing to KD and control subjects from Yunnan province, China. We conducted association study analysis on the two groups.

RESULTS

In this study, we successfully identified 11 significant rare variants in two genes (MYH14 and RBP3) through the genotype/allele frequency analysis. A heterozygous variant (c.2650G > A, p.V884M) of the RBP3 gene was identified in 12 KD cases, while eight heterozygous variants (c.566G > A, p.R189H; c.1109 C > T, p.S370L; c.3917T > G, p.L1306R; c.4301G > A, p.R1434Q; c.5026 C > T, p.R1676W; c.5329 C > T, p.R1777C; c.5393 C > A, p.A1798D and c.5476 C > T, p.R1826C) of the MYH14 gene were identified in 8 KD cases respectively.

CONCLUSION

This study suggested that nine variants in MYH14 and RBP3 gene may be associated with KD susceptibility in the population from Yunnan province.

Rare genetic variants involved in multisystem inflammatory syndrome in children: a multicenter Brazilian cohort study

Introduction

Despite the existing data on the Multisystem Inflammatory Syndrome in Children (MIS-C), the factors that determine these patients evolution remain elusive. Answers may lie, at least in part, in genetics. It is currently under investigation that MIS-C patients may have an underlying innate error of immunity (IEI), whether of monogenic, digenic, or even oligogenic origin.

Methods

To further investigate this hypothesis, 30 patients with MIS-C were submitted to whole exome sequencing.

Results

Analyses of genes associated with MIS-C, MIS-A, severe covid-19, and Kawasaki disease identified twenty-nine patients with rare potentially damaging variants (50 variants were identified in 38 different genes), including those previously described in IFNA21 and IFIH1 genes, new variants in genes previously described in MIS-C patients (KMT2D, CFB, and PRF1), and variants in genes newly associated to MIS-C such as APOL1, TNFRSF13B, and G6PD. In addition, gene ontology enrichment pointed to the involvement of thirteen major pathways, including complement system, hematopoiesis, immune system development, and type II interferon signaling, that were not yet reported in MIS-C.

Discussion

These data strongly indicate that different gene families may favor MIS- C development. Larger cohort studies with healthy controls and other omics approaches, such as proteomics and RNAseq, will be precious to better understanding the disease dynamics.

Identification of Torquetenovirus Species in Patients with Kawasaki Disease Using a Newly Developed Species-Specific PCR Method

A next-generation sequencing (NGS) study identified a very high viral load of Torquetenovirus (TTV) in KD patients. We aimed to evaluate the feasibility of a newly developed quantitative species-specific TTV-PCR (ssTTV-PCR) method to identify the etiology of KD. We applied ssTTV-PCR to samples collected from 11 KD patients and 22 matched control subjects who participated in our previous prospective study. We used the NGS dataset from the previous study to validate ssTTV-PCR. The TTV loads in whole blood and nasopharyngeal aspirates correlated highly (Spearman's R = 0.8931, p < 0.0001, n = 33), supporting the validity of ssTTV-PCR. The ssTTV-PCR and NGS results were largely consistent. However, inconsistencies occurred when ssTTV-PCR was more sensitive than NGS, when the PCR primer sequences mismatched the viral sequences in the participants, and when the NGS quality score was low. Interpretation of NGS requires complex procedures. ssTTV-PCR is more sensitive than NGS but may fail to detect a fast-evolving TTV species. It would be prudent to update primer sets using NGS data. With this precaution, ssTTV-PCR can be used reliably in a future large-scale etiological study for KD.

Heart Disease and Stroke Statistics-2023 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2023 Statistical Update is the product of a full year's worth of effort in 2022 by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. The American Heart Association strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional COVID-19 (coronavirus disease 2019) publications, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Cross-protective humoral immunity to coronaviruses from SARS coronavirus 2-naïve sera of children with Kawasaki disease

OBJECTIVES

SARS coronavirus 2 (SARS-CoV-2)-associated multi-system inflammatory syndrome in children indicates that viruses can trigger a Kawasaki disease (KD)-like hyperinflammation. A plausible hypothesis was that coronavirus-specific 'holes' in humoral immunity could cause both diseases.

METHODS

To determine whether SARS-CoV-2-naïve patients with KD have inferior humoral immunity for the novel coronavirus, sera of children with KD and control children from year 2015 to 2021 were subjected to ELISA, microwestern, and neutralization assays to evaluate the capabilities in recognizing the receptor-binding domain of SARS-CoV-2, spotting spike proteins of three respiratory syndromic coronaviruses, and blocking SARS-CoV-2 from binding to angiotensin-converting enzyme 2 receptors in vitro, respectively.

RESULTS

29 patients with KD before 2019, 74 patients with KD in 2019 or 2020, 54 non-febrile controls, and 24 febrile controls were included in the study. SARS-CoV-2 was recognized on ELISA for both patients with KD in 2016 and those with KD in 2020. Microwestern demonstrated cross-reactive IgG in an all-or-none manner towards three spike proteins of syndromic coronaviruses regardless of sample year or KD status. The ratio between the sera that recognized all spike proteins and those that recognized none (51 vs. 47) was significantly higher from patients with KD than from non-febrile controls (17 vs. 32; p 0.047) but not from febrile controls (13 vs. 11; p 0.85). Most positive sera (12 of 17 controls, 5 of 8 patients with KD before 2019, and 28 of 33 patients with KD in 2019 or 2020) offered protection comparable to low-titre sera from the WHO reference panel.

DISCUSSION

Humoral immunity of SARS-CoV-2-naïve children with KD was not inferior to that of controls in offering cross-protection against the novel coronavirus.

Hygienic behaviors during the COVID-19 pandemic may decrease immunoglobulin G levels: Implications for Kawasaki disease

Background

Due to the coronavirus disease 2019 (COVID-19) pandemic, hygienic behaviors became a new norm since January 2020. The hygiene hypothesis predicts that an excessively hygienic environment may adversely affect human health.

Objective

We quantified the effect of COVID-19 on immunological parameters linked to the hygiene hypothesis.

Methods

We examined age-specific levels of total nonspecific immunoglobulin G (IgG) and IgE in individuals who visited Fukuoka Tokushukai Hospital between 2010 and 2021. Pre-COVID (2010–2019) and COVID (2020–2021) periods were compared.

Results

IgG levels steadily decreased throughout Pre-COVID period. IgG levels fell abruptly from the pre-COVID period to the COVID period in all age groups (P = 0.0271, < 0.3 years; P = 0.0096, 0.3–5 years; P = 0.0074, ≥ 5 years). The declines in IgG in < 0.3 years and that in ≥ 5 years accelerated during the COVID period. IgE levels were seasonal, but did not change noticeably from the pre-COVID to COVID period. IgG levels recorded for patients with Kawasaki disease (KD) (mean 709 mg/dL) were significantly lower than for matched control subjects (826 mg/dL) (P<0.0001).

Discussion

Hygienic behaviors during the COVID-19 outbreak decreased the chance of infection, which may explain the decreases in IgG levels in children and adults. Neonatal IgG declined, possibly because of the decrease in maternal IgG.

Conclusion

Hygienic behaviors decreased the IgG levels in all age groups, from neonates to adults. This downturn in IgG may lead to vulnerability to infections as well as to KD.

IgA Vasculitis: Influence of CD40, BLK and BANK1 Gene Polymorphisms

CD40, BLK and BANK1 genes involved in the development and signaling of B-cells are identified as susceptibility loci for numerous inflammatory diseases. Accordingly, we assessed the potential influence of CD40, BLK and BANK1 on the pathogenesis of immunoglobulin-A vasculitis (IgAV), predominantly a B-lymphocyte inflammatory condition. Three genetic variants within CD40 (rs1883832, rs1535045, rs4813003) and BLK (rs2254546, rs2736340, rs2618476) as well as two BANK1 polymorphisms (rs10516487, rs3733197), previously associated with inflammatory diseases, were genotyped in 382 Caucasian patients with IgAV and 955 sex- and ethnically matched healthy controls. No statistically significant differences were observed in the genotype and allele frequencies of CD40, BLK and BANK1 when IgAV patients and healthy controls were compared. Similar results were found when CD40, BLK and BANK1 genotypes or alleles frequencies were compared between patients with IgAV stratified according to the age at disease onset or to the presence/absence of gastrointestinal or renal manifestations. Moreover, no CD40, BLK and BANK1 haplotype differences were disclosed between patients with IgAV and healthy controls and between patients with IgAV stratified according to the clinical characteristics mentioned above. Our findings indicate that CD40, BLK and BANK1 do not contribute to the genetic background of IgAV.

IL-1 and autoinflammatory disease: biology, pathogenesis and therapeutic targeting

Over 20 years ago, it was first proposed that autoinflammation underpins a handful of rare monogenic disorders characterized by recurrent fever and systemic inflammation. The subsequent identification of novel, causative genes directly led to a better understanding of how the innate immune system is regulated under normal conditions, as well as its dysregulation associated with pathogenic mutations. Early on, IL-1 emerged as a central mediator for these diseases, based on data derived from patient cells, mutant mouse models and definitive clinical responses to IL-1 targeted therapy. Since that time, our understanding of the mechanisms of autoinflammation has expanded beyond IL-1 to additional innate immune processes. However, the number and complexity of IL-1-mediated autoinflammatory diseases has also multiplied to include additional monogenic syndromes with expanded genotypes and phenotypes, as well as more common polygenic disorders seen frequently by the practising clinician. In order to increase physician awareness and update rheumatologists who are likely to encounter these patients, this review discusses the general pathophysiological concepts of IL-1-mediated autoinflammation, the epidemiological and clinical features of specific diseases, diagnostic challenges and approaches, and current and future perspectives for therapy.

Preterm birth and Kawasaki disease: a nationwide Japanese population-based study

BACKGROUND

Previous studies showed that preterm birth increased the risk for hospital admissions in infancy and childhood due to some acute diseases. However, the risk of preterm children developing Kawasaki disease remains unknown. In the present study, we investigate whether preterm birth increased the morbidity of Kawasaki disease.

METHODS

We included 36,885 (34,880 term and 2005 preterm) children born in 2010 in Japan. We examined the association between preterm birth and hospitalization due to Kawasaki disease using a large nationwide survey in Japan.

RESULTS

In log-linear regression models that were adjusted for children's characteristics (sex, singleton birth, and parity), parental characteristics (maternal age, maternal smoking, paternal smoking, maternal education, and paternal income), and residential area, preterm infants were more likely to be hospitalized due to Kawasaki disease (adjusted risk ratio: 1·55, 95% confidence interval: 1.01-2.39). We then examined whether breastfeeding status modified the potential adverse effects of preterm birth on health outcome. Preterm infants with partial breastfeeding or formula feeding had a significantly higher risk of hospitalization due to Kawasaki disease compared with term infants with exclusive breastfeeding.

CONCLUSIONS

Preterm infants were at a high risk for Kawasaki disease, and exclusive breastfeeding might prevent this disease among preterm infants.

IMPACT

Previous studies showed that preterm birth increased the risk for hospital admissions in infancy and childhood due to some acute diseases, however, the risk of preterm children developing Kawasaki disease remains unknown. This Japanese large population-based study showed that preterm infants were at a high risk for Kawasaki disease for the first time. Furthermore, this study suggested that exclusively breastfeeding might prevent Kawasaki disease among preterm infants.

The EIF2AK4/rs4594236 AG/GG Genotype Is a Hazard Factor of Immunoglobulin Therapy Resistance in Southern Chinese Kawasaki Disease Patients

Background: Kawasaki disease (KD) is an acute, self-limited vasculitis disorder of unknown etiology in children. Immunologic abnormalities were detected during the acute phase of KD, which reflected that the effect cells of the activated immune system markedly increased cytokine production. High-dose intravenous immunoglobulin (IVIG) therapy is effective in resolving inflammation from KD and reducing occurrence of coronary artery abnormalities. However, 10%–20% of KD patients have no response to IVIG therapy, who were defined as IVIG resistance. Furthermore, these patients have persistent inflammation and increased risk of developing coronary artery aneurysm (CAA). EIF2AK4 is a stress sensor gene and can be activated by pathogen infection. In addition, the polymorphisms of EIF2AK4 were associated with various blood vessel disorders. However, it remains unclear whether the EIF2AK4 gene polymorphisms were related to IVIG therapy outcome in KD patients.

Methods:EIF2AK4/rs4594236 polymorphism was genotyped in 795 IVIG response KD patients and 234 IVIG resistant KD patients through TaqMan, a real-time polymerase chain reaction. The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of association between EIF2AK4/rs4594236 polymorphism and IVIG therapeutic effects.

Results: Our results showed that the EIF2AK4/rs4594236 AG/GG genotype was significantly associated with increased risk to IVIG resistance compared to the AA genotype (AG vs. AA: adjusted ORs = 1.71, 95% CIs = 1.17–2.51, and p = 0.0061; GG vs. AA: adjusted ORs = 2.09, 95% CIs = 1.36–3.23, and p = 0.0009; AG/GG vs. AA: adjusted ORs = 1.82, 95% CIs = 1.27–2.63, and p = 0.0013; and GG vs. AA/AG: adjusted ORs = 1.45, 95% CI = 1.04–2.02, and p = 0.0306). Furthermore, the stratified analysis of age and gender in the KD cohort indicated that male patients carrying the rs4594236 AG/GG genotype tends to be more resistant to IVIG therapy than female patients.

Conclusion: These results suggested that EIF2AK4/rs4594236 polymorphism might be associated with increased risk of IVIG resistance in southern Chinese KD patients.

Identification of rare coding variants associated with Kawasaki disease by whole exome sequencing

Kawasaki disease (KD) is an acute pediatric vasculitis that affects genetically susceptible infants and children. To identify coding variants that influence susceptibility to KD, we conducted whole exome sequencing of 159 patients with KD and 902 controls, and performed a replication study in an independent 586 cases and 732 controls. We identified five rare coding variants in five genes (FCRLA, PTGER4, IL17F, CARD11, and SIGLEC10) associated with KD (odds ratio [OR], 1.18 to 4.41; p = 0.0027–0.031). We also performed association analysis in 26 KD patients with coronary artery aneurysms (CAAs; diameter > 5 mm) and 124 patients without CAAs (diameter < 3 mm), and identified another five rare coding variants in five genes (FGFR4, IL31RA, FNDC1, MMP8, and FOXN1), which may be associated with CAA (OR, 3.89 to 37.3; p = 0.0058–0.0261). These results provide insights into new candidate genes and genetic variants potentially involved in the development of KD and CAA.

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.

Hygiene Hypothesis as the Etiology of Kawasaki Disease: Dysregulation of Early B Cell Development

Kawasaki disease (KD) is an acute systemic vasculitis that occurs predominantly in children under 5 years of age. Despite much study, the etiology of KD remains unknown. However, epidemiological and immunological data support the hygiene hypothesis as a possible etiology. It is thought that more sterile or clean modern living environments due to increased use of sanitizing agents, antibiotics, and formula feeding result in a lack of immunological challenges, leading to defective or dysregulated B cell development, accompanied by low IgG and high IgE levels. A lack of B cell immunity may increase sensitivity to unknown environmental triggers that are nonpathogenic in healthy individuals. Genetic studies of KD show that all of the KD susceptibility genes identified by genome-wide association studies are involved in B cell development and function, particularly in early B cell development (from the pro-B to pre-B cell stage). The fact that intravenous immunoglobulin is an effective therapy for KD supports this hypothesis. In this review, I discuss clinical, epidemiological, immunological, and genetic studies showing that the etiopathogenesis of KD in infants and toddlers can be explained by the hygiene hypothesis, and particularly by defects or dysregulation during early B cell development.

Single-Nucleotide Polymorphism LncRNA AC008392.1/rs7248320 in CARD8 is Associated with Kawasaki Disease Susceptibility in the Han Chinese Population

Background

Kawasaki disease (KD) is a multisystem vasculitis in infants and young children and involved in the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome activation. Genetic factors may increase the risk of KD. To assess the association between rs7248320 in long noncoding RNA (lncRNA) AC008392.1 located in the upstream region of CARD8 and the risk of KD, a case–control study was conducted in the Han Chinese population.

Methods

This study genotyped the polymorphism rs7248320 in the lncRNA AC008392.1 gene using the TaqMan real-time polymerase chain reaction assay. The genetic contribution of rs7248320 was evaluated using odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression analysis. The association between rs7248320 and KD susceptibility was analyzed by performing a hospital-based case–control study including 559 KD patients and 1055 non-KD controls.

Results

In this study, a significant relationship between rs7248320 and KD risk was observed in the genotype/allele frequency distribution. The rs7248320 polymorphism was associated with a significantly decreased risk of KD after adjustment for age and sex (AG vs AA: adjusted OR = 0.80, 95% CI: 0.64–0.99, P = 0.0421; GG vs AA: adjusted OR = 0.71, 95% CI: 0.51–1.00, P = 0.0492; AG/GG vs AA: adjusted OR = 0.78, 95% CI: 0.63–0.96, P = 0.0186). Moreover, the rs7248320 G allele also exhibited a decreased risk for KD (adjusted OR = 0.83, 95% CI: 0.72–0.97, P = 0.0193) compared with the A allele. In the stratification analysis, compared to the rs7248320 AA genotype, AG/GG genotypes were more protective for males (OR = 0.71, 95% CI: 0.55–0.93, P = 0.0122).

Conclusion

This study suggests for the first time that the lncRNA AC008392.1 rs7248320 polymorphism may be involved in KD susceptibility in the Han Chinese population.

Clinical Characteristics of Patients With Kawasaki Disease Whose Siblings Had the Same Disease

BACKGROUND

Some patients with Kawasaki disease (KD) have siblings who developed the same disease. Using a large-scale epidemiologic dataset, the present study aimed to determine the clinical characteristics of this population.

METHODS

We analyzed 89,725 patients diagnosed with KD during 2011-2018 who were registered in the nationwide Japanese KD survey database. Multivariable logistic regression analyses were performed to determine factors associated with sibling history of KD.

RESULTS

Of the 89,725 patients, 1777 (2%) had sibling history of KD. Annual prevalence ranged from 1.5% to 2.3% during the study period and showed a tendency toward an increasing trend. Patients with recurrent KD and parental history of KD were significantly associated with sibling history of KD (adjusted odds ratio [95% confidence interval] = 2.15 [1.82-2.54] and 2.64 [2.02-3.47], respectively). Although patients with a sibling history of KD were significantly associated with initial intravenous immunoglobulin treatment resistance (1.14 [1.02-1.28]), no significant association was found between sibling history and coronary artery abnormality development. Among patients with a sibling history of KD, male patients were less likely to have recurrent KD than female patients (0.68 [0.49-0.96]).

CONCLUSIONS

The significant association between sibling history and parental history may indicate genetic susceptibility to KD onset. Among those with a sibling history, recurrent KD was more likely to occur in female patients. Further studies focusing on this population may contribute toward identification of the cause of KD onset.

Identification of Novel Genomic-Variant Patterns of OR56A5, OR52L1, and CTSD in Retinitis Pigmentosa Patients by Whole-Exome Sequencing

Inherited retinal dystrophies (IRDs) are rare but highly heterogeneous genetic disorders that affect individuals and families worldwide. However, given its wide variability, its analysis of the driver genes for over 50% of the cases remains unexplored. The present study aims to identify novel driver genes, disease-causing variants, and retinitis pigmentosa (RP)-associated pathways. Using family-based whole-exome sequencing (WES) to identify putative RP-causing rare variants, we identified a total of five potentially pathogenic variants located in genes OR56A5, OR52L1, CTSD, PRF1, KBTBD13, and ATP2B4. Of the variants present in all affected individuals, genes OR56A5, OR52L1, CTSD, KBTBD13, and ATP2B4 present as missense mutations, while PRF1 and CTSD present as frameshift variants. Sanger sequencing confirmed the presence of the novel pathogenic variant PRF1 (c.124_128del) that has not been reported previously. More causal-effect or evidence-based studies will be required to elucidate the precise roles of these SNPs in the RP pathogenesis. Taken together, our findings may allow us to explore the risk variants based on the sequencing data and upgrade the existing variant annotation database in Taiwan. It may help detect specific eye diseases such as retinitis pigmentosa in East Asia.

Combined Single Nucleotide Variants of ORAI1 and BLK in a Child with Refractory Kawasaki Disease

Kawasaki disease (KD) is a systemic vasculitis with an unknown etiology affecting young children. Although intravenous immunoglobulin (IVIG) plus acetylsalicylic acid is effective in most cases, approximately 10–20% of patients do not respond to this therapy. An 8-month-old boy was admitted to a local hospital with the presumptive diagnosis of KD. He received IVIG twice and four series of methylprednisolone pulse therapy from the third to the tenth day of illness. Despite these treatments, his fever persisted with the development of moderate dilatations of the coronary arteries. A diagnosis of refractory KD was made, and infliximab with oral prednisolone was administered without success. Defervescence was finally achieved by cyclosporine A, an inhibitor of the signaling pathway of the calcineurin/nuclear factor of activated T cells (NFAT). Whole-genome sequencing of his deoxyribonucleic acid samples disclosed two single nucleotide variants (SNVs) in disease-susceptibility genes in Japanese KD patients, ORAI1 (rs3741596) and BLK (rs2254546). In summary, the refractory nature of the present case could be explained by the presence of combined SNVs in susceptibility genes associated with upregulation of the calcineurin/NFAT signaling pathway. It may provide insights for stratifying KD patients based on the SNVs in their susceptibility genes.

SARS-CoV-2-related MIS-C: A key to the viral and genetic causes of Kawasaki disease?

Multisystem inflammatory syndrome in children (MIS-C) emerged in April 2020 in communities with high COVID-19 rates. This new condition is heterogenous but resembles Kawasaki disease (KD), a well-known but poorly understood and clinically heterogenous pediatric inflammatory condition for which weak associations have been found with a myriad of viral illnesses. Epidemiological data clearly indicate that SARS-CoV-2 is the trigger for MIS-C, which typically occurs about 1 mo after infection. These findings support the hypothesis of viral triggers for the various forms of classic KD. We further suggest that rare inborn errors of immunity (IEIs) altering the immune response to SARS-CoV-2 may underlie the pathogenesis of MIS-C in some children. The discovery of monogenic IEIs underlying MIS-C would shed light on its pathogenesis, paving the way for a new genetic approach to classic KD, revisited as a heterogeneous collection of IEIs to viruses.

Association of an IGHV3-66 gene variant with Kawasaki disease

In a meta-analysis of three GWAS for susceptibility to Kawasaki disease (KD) conducted in Japan, Korea, and Taiwan and follow-up studies with a total of 11,265 subjects (3428 cases and 7837 controls), a significantly associated SNV in the immunoglobulin heavy variable gene (IGHV) cluster in 14q33.32 was identified (rs4774175; OR = 1.20, P = 6.0 × 10-9). Investigation of nonsynonymous SNVs of the IGHV cluster in 9335 Japanese subjects identified the C allele of rs6423677, located in IGHV3-66, as the most significant reproducible association (OR = 1.25, P = 6.8 × 10-10 in 3603 cases and 5731 controls). We observed highly skewed allelic usage of IGHV3-66, wherein the rs6423677 A allele was nearly abolished in the transcripts in peripheral blood mononuclear cells of both KD patients and healthy adults. Association of the high-expression allele with KD strongly indicates some active roles of B-cells or endogenous immunoglobulins in the disease pathogenesis. Considering that significant association of SNVs in the IGHV region with disease susceptibility was previously known only for rheumatic heart disease (RHD), a complication of acute rheumatic fever (ARF), these observations suggest that common B-cell related mechanisms may mediate the symptomology of KD and ARF as well as RHD.

Integration of genome-wide association study and expression quantitative trait locus mapping for identification of endometriosis-associated genes

To determine whether genetic predisposition to endometriosis varies depending on ethnicity and in association with expression quantitative trait loci (eQTL) in a Taiwanese population. We conducted a genome-wide association study (GWAS) and replicated it in 259 individuals with laparoscopy-confirmed stage III or IV endometriosis (cases) and 171 women without endometriosis (controls). Their genomic DNA was extracted from blood and evaluated by the GWAS of Taiwan Biobank Array. Novel genetic variants that predispose individuals to endometriosis were identified using GWAS and replication, including rs10739199 (P = 6.75 × 10^-5) and rs2025392 (P = 8.01 × 10^-5) at chromosome 9, rs1998998 (P = 6.5 × 10^-6) at chromosome 14, and rs6576560 (P = 9.7 × 10^-6) at chromosome 15. After imputation, strong signals were exhibited by rs10822312 (P = 1.80 × 10^-7) at chromosome 10, rs58991632 (P = 1.92 × 10^-6) and rs2273422 (P = 2.42 × 10^-6) at chromosome 20, and rs12566078 (P = 2.5 × 10^-6) at chromosome 1. We used the Genotype-Tissue Expression (GTEx) database to observe eQTL. Among these SNPs, the cis-eQTL rs13126673 of inturned planar cell polarity protein (INTU) showed significant association with INTU expression (P = 5.1 × 10^-33). Moreover, the eQTL analysis was performed on endometriotic tissues from women with endometriosis. The expression of INTU in 78 endometriotic tissue of women with endometriosis is associated with rs13126673 genotype (P = 0.034). To our knowledge, this is the first GWAS to link endometriosis and eQTL in a Taiwanese population.

IgA Levels Are Associated with Coronary Artery Lesions in Kawasaki Disease

Background and Objectives

Kawasaki disease (KD) is an acute systemic vasculitis that affects the coronary arteries. Abnormal immune reactions are thought to contribute to disease pathogenesis. The effect of immunoglobulin (Ig) isotype (IgG, IgA, IgM, and IgE) on inflammatory data and clinical outcomes of patients with KD was examined.

Methods

Ig levels in 241 patients with KD were measured during the acute, subacute, convalescent, and normal phases of the disease.

Results

Compared with reference Ig values, IgG, IgA, and IgM levels were significantly higher in the subacute phase, while IgE levels were elevated in 73.9% (178/241) of patients with KD in all clinical phases. However, high IgE levels were not associated with clinical outcomes, including intravenous immunoglobulin unresponsiveness and coronary artery lesions (CALs). Significantly more CALs were observed in the high IgA group than in the normal IgA group (44.7% vs. 20.8%, respectively; p<0.01). In addition, IgA levels in the acute phase (p=0.038) were 2.2-fold higher, and those in the subacute phase were 1.7-fold higher (p <0.001), in the CAL group than in the non-CAL group. IgA concentrations increased along with the size of the coronary artery aneurysm (p <0.001). Furthermore, there was a strong correlation between IgA levels and CAL size (r=0.435, p<0.001), with a high odds ratio of 2.58 (p=0.022).

Conclusions

High IgA levels in patients with KD are prognostic for the risk of CALs.

Epigenetics in Kawasaki Disease

Kawasaki disease (KD) is a common febrile multisystemic inflammatory illness in children that preferentially affects coronary arteries. Children with KD who develop coronary artery aneurysms have a life-long risk of premature coronary artery disease. Hypothesis of inherent predisposition to KD is supported by epidemiological evidence that suggests increased risk of development of disease in certain ethnicities and in children with a previous history of KD in siblings or parents. However, occurrence of cases in clusters, seasonal variation, and very low risk of recurrence suggests an acquired trigger (such as infections) for the development of illness. Epigenetic mechanisms that modulate gene expression can plausibly explain the link between genetic and acquired predisposing factors in KD. Analysis of epigenetic factors can also be used to derive biomarkers for diagnosis and prognostication in KD. Moreover, epigenetic mechanisms can also help in pharmacogenomics with the development of targeted therapies. In this review, we analysed the available literature on epigenetic factors such as methylation, micro-RNAs, and long non-coding RNAs in KD and discuss how these mechanisms can help us better understand the disease pathogenesis and advance the development of new biomarkers in KD.

Association Between rs12037447, rs146732504, rs151078858, rs55723436, and rs6094136 Polymorphisms and Kawasaki Disease in the Population of Polish Children

Background: Kawasaki disease (KD) is an acute self-limited febrile vasculitis that mainly affects young children. Coronary artery involvement is the most serious complication in children with KD. It is currently the leading cause of acquired cardiac disease in children from developed countries. Literature data indicate a significant role of genetic susceptibility to KD. Objective: The aim of this study was to perform the first Genome-Wide Association Study (GWAS) in a population of Polish children with KD and identify susceptible genes involved in the pathogenesis of KD. Materials and Methods: The blood samples of Kawasaki disease patients (n = 119) were collected between 2016 and 2020, isolated and stored at the Department of Pediatrics, Nutrition and Metabolic Diseases, Children's Memorial Health Institute in Warsaw. The control group was based on Polish donors (n = 6,071) registered as the POPULOUS collection at the Biobank Lab of The Department of Molecular Biophysics in University of Lodz. DNA samples were genotyped for 558,231 Single Nucleotide Polymorphisms (SNPs) using the 24 × 1 Infinium HTS Human Core Exome microarrays according to the protocol provided by the manufacturer. In order to discover and verify genetic risk-factors for KD, association analysis was carried out using PLINK 1.9. Results: Of all 164,395 variants, 5 were shown to occur statistically (p_adjusted < 0.05) more frequent in Kawasaki disease patients than in controls. Those are: rs12037447 in non-coding sequence (p_adjusted = 8.329 × 10^-4, OR = 8.697, 95% CI; 3.629-20.84) and rs146732504 in KIF25 (p_adjusted = 0.007354, OR = 11.42, 95% CI; 3.79-34.43), rs151078858 in PTPRJ (p_adjusted = 0.04513, OR = 8.116, 95% CI; 3.134-21.01), rs55723436 in SPECC1L (p_adjusted = 0.04596, OR = 5.596, 95% CI; 2.669-11.74), rs6094136 in RPN2 (p_adjusted = 0.04755, OR = 10.08, 95% CI; 3.385-30.01) genes. Conclusion: Polymorphisms of genes KIF25, PTRPJ, SPECC1L, RNP2 may be linked with the incidence of Kawasaki disease in Polish children.

Perspective of Immunopathogenesis and Immunotherapies for Kawasaki Disease

Kawasaki Disease (KD) is an acute inflammatory illness that mostly occurs in children below 5 years of age, with intractable fever, mucocutaneous lesions, lymphadenopathy, and lesions of the coronary artery (CAL). KD is sharing clinical symptoms with systemic inflammatory syndrome in children (MIS-C) which is related to COVID-19. Certain genes are identified to be associated with KD, but the findings usually differ between countries and races. Human Leukocyte Antigen (HLA) allele types and toll-like receptor (TLR) expression are also correlated to KD. The acute hyperinflammation in KD is mediated by an imbalance between augmented T helper 17 (Th17)/Th1 responses with high levels of interleukin (IL)-6, IL-10, IL-17A, IFN-γ, and IP-10, in contrast to reduced Th2/Treg responses with lower IL-4, IL-5, FoxP3, and TGF-β expression. KD has varying phenotypic variations regarding age, gender, intravenous immunoglobulin (IVIG) resistance, macrophage activation and shock syndrome. The signs of macrophage activation syndrome (MAS) can be interpreted as hyperferritinemia and thrombocytopenia contradictory to thrombocytosis in typical KD; the signs of KD with shock syndrome (KDSS) can be interpreted as overproduction of nitric oxide (NO) and coagulopathy. For over five decades, IVIG and aspirin are the standard treatment for KD. However, some KD patients are refractory to IVIG required additional medications against inflammation. Further studies are proposed to delineate the immunopathogenesis of IVIG-resistance and KDSS, to identify high risk patients with genetic susceptibility, and to develop an ideal treatment regimen, such as by providing idiotypic immunoglobulins to curb cytokine storms, NO overproduction, and the epigenetic induction of Treg function.

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.

Comprehensive pathogen detection in sera of Kawasaki disease patients by high-throughput sequencing: a retrospective exploratory study

Background

Kawasaki disease (KD) is an idiopathic systemic vasculitis that predominantly damages coronary arteries in children. Various pathogens have been investigated as triggers for KD, but no definitive causative pathogen has been determined. As KD is diagnosed by symptoms, several days are needed for diagnosis. Therefore, at the time of diagnosis of KD, the pathogen of the trigger may already be diminished. The aim of this study was to explore comprehensive pathogens in the sera at the acute stage of KD using high-throughput sequencing (HTS).

Methods

Sera of 12 patients at an extremely early stage of KD and 12 controls were investigated. DNA and RNA sequences were read separately using HTS. Sequence data were imported into the home-brew meta-genomic analysis pipeline, PATHDET, to identify the pathogen sequences.

Results

No RNA virus reads were detected in any KD case except for that of equine infectious anemia, which is known as a contaminant of commercial reverse transcriptase. Concerning DNA viruses, human herpesvirus 6B (HHV-6B, two cases) and Anelloviridae (eight cases) were detected among KD cases as well as controls. Multiple bacterial reads were obtained from KD and controls. Bacteria of the genera Acinetobacter, Pseudomonas, Delfita, Roseomonas, and Rhodocyclaceae appeared to be more common in KD sera than in the controls.

Conclusion

No single pathogen was identified in serum samples of patients at the acute phase of KD. With multiple bacteria detected in the serum samples, it is difficult to exclude the possibility of contamination; however, it is possible that these bacteria might stimulate the immune system and induce KD.

Complex genetic signatures in immune cells underlie autoimmunity and inform therapy

We report on the influence of ~22 million variants on 731 immune cell traits in a cohort of 3,757 Sardinians. We detected 122 significant (P < 1.28 × 10^-11) independent association signals for 459 cell traits at 70 loci (53 of them novel) identifying several molecules and mechanisms involved in cell regulation. Furthermore, 53 signals at 36 loci overlapped with previously reported disease-associated signals, predominantly for autoimmune disorders, highlighting intermediate phenotypes in pathogenesis. Collectively, our findings illustrate complex genetic regulation of immune cells with highly selective effects on autoimmune disease risk at the cell-subtype level. These results identify drug-targetable pathways informing the design of more specific treatments for autoimmune diseases.

Validation of genome-wide associated variants for Kawasaki disease in a Taiwanese case-control sample

Kawasaki disease (KD) is an acute febrile systemic vasculitis of unknown etiology that affects infants and young children. Considerable evidence supports the hypothesis that there is a genetic basis for KD susceptibility. Genome-wide association studies (GWAS) have identified several genetic variants associated with KD. This study aims to replicate three novel KD-associated single nucleotide polymorphisms (SNPs), identified by GWAS in Japanese, in a Taiwanese population. Associations between these SNPs and development of coronary artery lesions (CALs) were also investigated. The rs2254546 A/G, rs2857151 A/G, and rs4813003 C/T SNPs were genotyped in 681 children with KD and 563 ethnically-matched healthy controls using TaqMan Assay or DNA sequencing. We found rs2254546 and rs4813003 SNPs were significantly associated with KD (G allele, odds ratio [OR] = 1.54, P = 1.0 × 10^–5; C allele, OR = 1.32, P = 8.1 × 10^–4). However, no evidence for associations with CAL development was observed. Our study successfully validates associations of the rs2254546 and rs4813003 SNPs with KD in a Taiwanese population. Further functional studies of the SNPs are important in understanding the pathogenesis of KD.

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.

Adjuvant herbal therapy for targeting susceptibility genes to Kawasaki disease: An overview of epidemiology, pathogenesis, diagnosis and pharmacological treatment of Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a self-limiting acute systemic vasculitis occur mainly in infants and young children under 5 years old. Although the use of acetylsalicylic acid (AAS) in combination with intravenous immunoglobulin (IVIG) remains the standard therapy to KD, the etiology, genetic susceptibility genes and pathogenic factors of KD are still un-elucidated.

PURPOSE

Current obstacles in the treatment of KD include the lack of standard clinical and genetic markers for early diagnosis, possible severe side effect of AAS (Reye's syndrome), and the refractory KD cases with resistance to IVIG therapy, therefore, this review has focused on introducing the current advances in the identification of genetic susceptibility genes, environmental factors, diagnostic markers and adjuvant pharmacological intervention for KD.

RESULTS

With an overall update in the development of KD from different aspects, our current bioinformatics data has suggested CASP3, CD40 and TLR4 as the possible pathogenic factors or diagnostic markers of KD. Besides, a list of herbal medicines which may work as the adjunct therapy for KD via targeting different proposed molecular targets of KD have also been summarized.

CONCLUSION

With the aid of modern pharmacological research and technology, it is anticipated that novel therapeutic remedies, especially active herbal chemicals targeting precise clinical markers of KD could be developed for accurate diagnosis and treatment of the disease.

A Comprehensive Update on Kawasaki Disease Vasculitis and Myocarditis

PURPOSE OF THE REVIEW

Kawasaki disease (KD) is a childhood systemic vasculitis of unknown etiology that causes coronary artery aneurysms (CAA), and if left undiagnosed can result in long-term cardiovascular complications and adult cardiac disease. Up to 20% of KD children fail to respond to IVIG, the mainstay of therapy, highlighting the need for novel therapeutic strategies. Here we review the latest findings in the field regarding specific etiology, genetic associations, and advancements in treatment strategies to prevent coronary aneurysms.

RECENT FINDINGS

Recent discoveries using the Lactobacillus casei cell wall extract (LCWE)-induced KD vasculitis mouse model have accelerated the study of KD pathophysiology and have advanced treatment strategies including clinical trials for IL-1R antagonist, Anakinra. KD remains an elusive pediatric vasculitis syndrome and is the leading cause of acquired heart disease among children in the USA and developed countries. Advancements in combination treatment for refractory KD with further understanding of novel genetic risk factors serve as a solid foundation for future research endeavors in the field.

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.

Prediction for Intravenous Immunoglobulin Resistance Combining Genetic Risk Loci Identified From Next Generation Sequencing and Laboratory Data in Kawasaki Disease

Background: Kawasaki disease (KD) is the most common cause of acquired heart disease. A proportion of patients were resistant to intravenous immunoglobulin (IVIG), the primary treatment of KD, and the mechanism of IVIG resistance remains unclear. The accuracy of current models predictive of IVIG resistance is insufficient and doesn't meet the clinical expectations. Objectives: To develop a scoring model predicting IVIG resistance of patients with KD. Methods: We recruited 330 KD patients (50 IVIG non-responders, 280 IVIG responders) and 105 healthy children to explore the susceptibility loci of IVIG resistance in Kawasaki disease. A next generation sequencing technology that focused on 4 immune-related pathways and 472 single nucleotide polymorphisms (SNPs) was performed. An R package SNPassoc was used to identify the risk loci, and student's t-test was used to identify risk factors associated with IVIG resistance. A random forest-based scoring model of IVIG resistance was built based on the identified specific SNP loci with the laboratory data. Results: A total of 544 significant risk loci were found associated with IVIG resistance, including 27 previous published SNPs. Laboratory test variables, including erythrocyte sedimentation rate (ESR), platelet (PLT), and C reactive protein, were found significantly different between IVIG responders and non-responders. A scoring model was built using the top 9 SNPs and clinical features achieving an area under the ROC curve of 0.974. Conclusions: It is the first study that focused on immune system in KD using high-throughput sequencing technology. Our findings provided a prediction of the IVIG resistance by integrating the genotype and clinical variables. It also suggested a new perspective on the pathogenesis of IVIG resistance.

Current State of Precision Medicine in Primary Systemic Vasculitides

Precision medicine (PM) is an emerging data-driven health care approach that integrates phenotypic, genomic, epigenetic, and environmental factors unique to an individual. The goal of PM is to facilitate diagnosis, predict effective therapy, and avoid adverse reactions specific for each patient. The forefront of PM is in oncology; nonetheless, it is developing in other fields of medicine, including rheumatology. Recent studies on elucidating the genetic architecture of polygenic and monogenic rheumatological diseases have made PM possible by enabling physicians to customize medical treatment through the incorporation of clinical features and genetic data. For complex inflammatory disorders, the prevailing paradigm is that disease susceptibility is due to additive effects of common reduced-penetrance gene variants and environmental factors. Efforts have been made to calculate cumulative genetic risk score (GRS) and to relate specific susceptibility alleles for use of target therapies. The discovery of rare patients with single-gene high-penetrance mutations informed our understanding of pathways driving systemic inflammation. Here, we review the advances in practicing PM in patients with primary systemic vasculitides (PSVs). We summarize recent genetic studies and discuss current knowledge on the contribution of epigenetic factors and extracellular vesicles (EVs) in disease progression and treatment response. Implementation of PM in PSVs is a developing field that will require analysis of a large cohort of patients to validate data from genomics, transcriptomics, metabolomics, proteomics, and epigenomics studies for accurate disease profiling. This multi-omics approach to study disease pathogeneses should ultimately provide a powerful tool for stratification of patients to receive tailored optimal therapies and for monitoring their disease activity.

Immunoglobulin profiling identifies unique signatures in patients with Kawasaki disease during intravenous immunoglobulin treatment

Identifying the causes of high fever syndromes such as Kawasaki disease (KD) remains challenging. To investigate pathogen exposure signatures in suspected pathogen-mediated diseases such as KD, we performed immunoglobulin (Ig) profiling using a next-generation sequencing method. After intravenous Ig (IVIG) treatment, we observed disappearance of clonally expanded IgM clonotypes, which were dominantly observed in acute-phase patients. The complementary-determining region 3 (CDR3) sequences of dominant IgM clonotypes in acute-phase patients were commonly observed in other Ig isotypes. In acute-phase KD patients, we identified 32 unique IgM CDR3 clonotypes shared in three or more cases. Furthermore, before the IVIG treatment, the sums of dominant IgM clonotypes in IVIG-resistant KD patients were significantly higher than those of IVIG-sensitive KD patients. Collectively, we demonstrate a novel approach for identifying certain Ig clonotypes for potentially interacting with pathogens involved in KD; this approach could be applied for a wide variety of fever-causing diseases of unknown origin.

Association between the miRNA-149 rs2292832 T>C polymorphism and Kawasaki disease susceptibility in a southern Chinese population

Background

Kawasaki disease (KD), which is characterized by vasculitis, is prone to occur in patients under 5 years of age, has an ambiguous etiology, and displays coronary artery lesions as the chief complication. Previous studies have linked miRNA‐149 to cancers, and rs2292832 T>C is related to allergic diseases and inflammatory bowel disease, which both show immune system disorders and coronary artery disease. Therefore, we performed a study concentrating on the association between the miRNA‐149 rs2292832 T>C polymorphism and KD susceptibility.

Methods

The subjects enrolled were 532 children with KD and 623 controls. We used TaqMan real‐time PCR to obtain the genotypes of the rs2292832 T>C polymorphism.

Results

Ultimately, no significant association was found between the miRNA‐149 rs2292832 T>C polymorphism and KD susceptibility, even in stratification analysis.

Conclusion

Our results indicated that in southern Chinese patients, the miRNA‐149 rs2292832 T>C polymorphism did not affect KD susceptibility, which needs to be further confirmed.

Leveraging Genetic Findings for Precision Medicine in Vasculitis

Vasculitides are a heterogeneous group of low frequent disorders, mainly characterized by the inflammation of blood vessels that narrows or occlude the lumen and limits the blood flow, leading eventually to significant tissue and organ damage. These disorders are classified depending on the size of the affected blood vessels in large, medium, and small vessel vasculitis. Currently, it is known that these syndromes show a complex etiology in which both environmental and genetic factors play a major role in their development. So far, these conditions are not curable and the therapeutic approaches are mainly symptomatic. Moreover, a percentage of the patients do not adequately respond to standard treatments. Over the last years, numerous genetic studies have been carried out to identify susceptibility loci and biological pathways involved in vasculitis pathogenesis as well as potential genetic predictors of treatment response. The ultimate goal of these studies is to identify new therapeutic targets and to improve the use of existing drugs to achieve more effective treatments. This review will focus on the main advances made in the field of genetics and pharmacogenetics of vasculitis and their potential application for ameliorating long-term outcomes in patient management and in the development of precision medicine.

A low-frequency IL4R locus variant in Japanese patients with intravenous immunoglobulin therapy-unresponsive Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a systemic vasculitis which may be associated with coronary artery aneurysms. A notable risk factor for the development of coronary artery aneurysms is resistance to intravenous immunoglobulin (IVIG) therapy, which comprises standard treatment for the acute phase of KD. The cause of IVIG resistance in KD is largely unknown; however, the contribution of genetic factors, especially variants in immune-related genes, has been suspected.

METHODS

To explore genetic variants related to IVIG-unresponsiveness, we designated KD patients who did not respond to both first and second courses of IVIG therapy as IVIG-unresponsive patients. Using genomic DNA from 30 IVIG-unresponsive KD patients, we performed pooled genome sequencing targeting 39 immune-related cytokine receptor genes.

RESULTS

The single nucleotide variant (SNV), rs563535954 (located in the IL4R locus), was concentrated in IVIG-unresponsive KD patients. Individual genotyping showed that the minor allele of rs563535954 was present in 4/33 patients with IVIG-unresponsive KD, compared with 20/1063 individuals in the Japanese genome variation database (odds ratio = 7.19, 95% confidence interval 2.43-21.47). Furthermore, the minor allele of rs563535954 was absent in 42 KD patients who responded to IVIG treatment (P = 0.0337), indicating that a low-frequency variant, rs563535954, is associated with IVIG-unresponsiveness in KD patients. Although rs563535954 is located in the 3'-untranslated region of IL4R, there was no alternation in IL4R expression associated with the mior allele of rs563535954. However, IVIG-unresponsive patients that exhibited the minor allele of rs563535954 tended to be classified into the low-risk group (based on previously reported risk scores) for prediction of IVIG-resistance. Therefore, IVIG-unresponsiveness associated with the minor allele of rs563535954 might differ from IVIG-unresponsiveness associated with previous risk factors used to evaluate IVIG-unresponsiveness in KD.

CONCLUSION

These findings suggest that the SNV rs563535954 could serve as a predictive indicator of IVIG-unresponsiveness, thereby improving the sensitivity of risk scoring systems, and may aid in prevention of coronary artery lesions in KD patients.

Vasculitis: Decade in Review

BACKGROUND

In the last decade, we have come to better understand and manage the vasculitides. The classification of vasculitides has been revised. Genome- wide association studies and linkage analyses have been undertaken in hope of better understanding the pathogenesis of vasculitides. Comprehensive genetic studies have highlighted new pathways that may guide us in more targeted therapies. Description of the monogenic forms of vasculitis, such as deficiency of adenosine deaminase type 2 (DADA2), Haploinsufficiency of A20 (HA20), have introduced a new perspective to vasculopathies, and introduced alternative treatments for these diseases.

CONCLUSION

In this review, the important discoveries in pathogenesis and consensus treatment recommendations from the past decade will be summarized.