Causes of Kawasaki Disease-From Past to Present

Decreased incidence of Kawasaki disease in South Korea during the SARS-CoV-2 pandemic

Purpose

Analyzing Kawasaki disease epidemiology during the SARS-CoV-2 pandemic in South Korea using 2012-2020 National Health Insurance Service data.

Methods

The incidence of Kawasaki disease for 2012-2020 was investigated to identify changes in incidence after the start of the pandemic. National Health Insurance Service data from the Republic of Korea were used. Kawasaki disease was defined based on the International Statistical Classification of Diseases and Related Health Problems, the Tenth Revision diagnostic code (M30.3), and the intravenous immunoglobulin prescription code. Prescription history was collected for the following medications: intravenous immunoglobulin, aspirin, corticosteroids, tumor necrosis factor-α antagonist, clopidogrel, and anticoagulation drugs.

Results

The Kawasaki disease incidence per 100,000 individuals younger than 5 years was 238.9, 230.0, and 141.2 in 2018, 2019, and 2020, respectively. Regarding the incidence from 2012 to 2020, it was the highest in 2018 and decreased to 141.2 (p < 0.001) in 2020, after the start of the pandemic. In 2020, 28.3% of all patients with KD were infants, a percentage significantly higher than that of the previous year (p < 0.001). There was biphasic seasonality in the monthly Kawasaki disease incidence. The Kawasaki disease incidence was the highest in winter followed by that in early summer.

Conclusion

After the start of the pandemic, the Kawasaki disease incidence decreased, and the percentage of patients with Kawasaki disease aged <1 year increased. These findings provide support for the hypothesis suggesting an infectious trigger in Kawasaki disease.

Efficacy and safety of infliximab in the treatment of Kawasaki disease: A systematic review and meta-analysis

Infliximab is a monoclonal antibody specifically binding tumor necrosis factor-alpha and has been approved for the treatment of several inflammatory disorders. However, the efficacy of infliximab in primary treatment of Kawasaki disease (KD) or retreatment of intravenous immunoglobulin (IVIG)-resistant KD in children is controversial. Therefore, we conducted a meta-analysis to compare the efficacy of infliximab alone or in combination with IVIG to IVIG. Eligible randomized and non-randomized trials were retrieved by searching literature databases prior to May 31, 2023. Pooled odds ratio (OR) and 95% confidence interval (95% CI) were calculated for dichotomous variables, and mean difference (MD) with 95% CI was estimated for continuous variables. A total of 14 eligible studies comprising 1257 participants were included. In refractory KD, infliximab alone was associated with a higher effectiveness rate (OR = 4.48, 95% CI 2.67-7.52) and defervescence rate (OR = 5.01, 95% CI 2.99-8.37) and resulted in a 1.08-day-shorter duration of fever (95% CI 0.61-1.55, P < 0.001) and 1.36-day-shorter length of hospital stay (95% CI 0.65-2.08) compared with IVIG. Incidences of coronary artery lesions (CALs), newly developing CALs, and CAL regression did not differ between both groups. For initial treatment of KD, infliximab in addition to IVIG led to a nominally significant higher effectiveness rate (OR = 2.26, 95% CI 1.02-5.01) and a larger reduction of right coronary artery Z score (MD = -0.24, 95% CI -0.27 to -0.21) but did not show additional efficacy in improving other outcomes. The safety profile was similar between both groups.   Conclusion: The meta-analysis demonstrates that infliximab alone is a well-tolerated and effective treatment for IVIG-resistant KD. The additional efficacy of infliximab to IVIG for initial treatment of KD is limited. More large and high-quality trials are needed to confirm the efficacy of infliximab, especially for intensification of primary treatment for KD. What is Known: • Infliximab is a novel monoclonal antibody specifically blocking tumor necrosis factor-alpha and is approved for treatment of several immune-mediated inflammatory disorders. • The efficacy of infliximab in treating children with Kawasaki disease is controversial. What is New: • Infliximab is an effective and safe treatment for children with refractory Kawasaki disease but adds limited efficacy to intravenous immunoglobulin for initial treatment of Kawasaki disease.

Respiratory pathogen trends in patients with Kawasaki disease during the COVID-19 pandemic and respiratory syncytial virus epidemic in Japan

BACKGROUND

Although the etiology of Kawasaki disease (KD) remains unknown, the most common view is that an infectious agent triggers the activation of the inflammatory cascade in predisposed children. The coronavirus disease 2019 (COVID-19) pandemic has led to the establishment of infection control measures, which reduced the overall incidence of respiratory infections; however, a resurgence of respiratory syncytial virus (RSV) infection occurred in the summer of 2021. This study aimed to examine the relationship between respiratory pathogens and KD during the COVID-19 pandemic and the RSV epidemic in Japan between 2020 and 2021.

METHODS

We retrospectively reviewed the medical charts of pediatric patients with KD or respiratory tract infection (RTI) admitted to National Hospital Organization Okayama Medical Center between December 1, 2020, and August 31, 2021. All patients with KD and RTI underwent multiplex polymerase chain reaction testing upon admission. We classified patients with KD into the three subgroups-pathogen-negative, single pathogen-positive, and multi-pathogen-positive-and compared their laboratory data and clinical features.

RESULTS

This study enrolled 48 patients with KD and 269 with RTI. Rhinovirus and enterovirus were the most prevalent pathogens in both patients with KD and RTI (13 [27.1%] and 132 patients [49.1%], respectively). The clinical characteristics of the pathogen-negative KD group and the pathogen-positive KD group at diagnosis were similar; however, the pathogen-negative group tended to receive additional treatment, such as multiple courses of intravenous immunoglobulin, intravenous methylprednisolone, infliximab, cyclosporine A, and plasmapheresis, more frequently. The number of patients with KD remained stable when RTI was not prevalent but increased following the surge in RTI with RSV.

CONCLUSIONS

An epidemic of respiratory infections led to an increase in the incidence of KD. Patients with respiratory pathogen-negative KD could have greater recalcitrance to intravenous immunoglobulin than those with respiratory pathogen-positive KD.

Concomitant Kawasaki Disease and Rotavirus Infection-More Than Just a Coincidence: A Case Report

The definitive role of viral infections, such as rotavirus, in causing Kawasaki disease (KD) remains uncertain. However, the intriguing observation of concomitant rotavirus infection and KD suggests a potential association. This study aimed to investigate this relationship. We reported a case of concomitant KD and rotavirus infection complicated by hyponatraemia and anasarca. For the systematic review, we used three large databases, namely PubMed, Ovid, and Scopus, to search articles with the terms "Kawasaki" and "rotavirus". We also used Google Scholar as our secondary source. We included articles that fulfilled the following criteria: (i) articles reporting on children aged 18 and below; (ii) articles reporting on patients infected with rotavirus prior to or concomitant with KD; and (iii) articles written in English only. Three articles were included and analysed in combination with our reported patient. All patients exhibited gastrointestinal symptoms, including diarrhoea and vomiting, in addition to non-resolving fevers, which eventually manifested more signs and symptoms to support the diagnosis of KD. Stool samples from all patients revealed positive rotavirus antigens. Two patients (n = 2) were noted to have hyponatraemia and hypoalbuminaemia. Three (n = 3) manifested coronary artery abnormalities (CAA). Even though the relationship is not fully understood yet, it is known that the combination of these two pathologies can cause catastrophic immune responses and complications.

Calculating the fraction of Kawasaki disease potentially attributable to seasonal pathogens: a time series analysis

Background

Kawasaki disease is an acute, febrile, systemic vasculitis of children that primarily affects medium-sized blood vessels with a tropism for the coronary arteries. Although the etiological factors remain unknown, infections have been suggested as the trigger of Kawasaki disease. We sought to calculate the fraction of Kawasaki disease potentially attributable to seasonal infections.

Methods

This cohort study used a population-based time series analysis from the French hospitalisation database (Programme de Médicalisation des Systèmes d'Information), which includes all inpatients admitted to any public or private hospital in France. We included all children aged 0-17 years hospitalised for Kawasaki disease in France over 13 years. The monthly incidence of Kawasaki disease per 10,000 children over time was analysed by a quasi-Poisson regression model. The model accounted for seasonality by using harmonic terms (a pair of sines and cosines with 12-month periods). The circulation of eight common seasonal pathogens (adenovirus, influenza, metapneumovirus, Mycoplasma pneumoniae, norovirus, rhinovirus, rotavirus, respiratory syncytial virus, and Streptococcus pneumonia) over the same period was included in the model to analyse the fraction of Kawasaki disease potentially attributable to each pathogen. Infections were identified on the basis of polymerase chain reaction or rapid antigen testing in hospital laboratories.

Findings

Between Jan 1, 2007, and Dec 31, 2019, we included 10,337 children with Kawasaki disease and 442,762 children with the selected infectious diseases. In the Kawasaki disease cohort, the median age [IQR] was 2 [0-4] years, 6164 [59.6%] were boys. Adenovirus infection was potentially responsible for 24.4% [21.5-27.8] (p < 0.001) of Kawasaki diseases, Norovirus for 6.7% [1.3-11.2] (p = 0.002), and RSV 4.6% [1.2-7.8] (p = 0.022). Sensitivity analyses found similar results.

Interpretation

This cohort study of data from a comprehensive national hospitalisation database indicated that approximately 35% of Kawasaki diseases was potentially attributable to seasonal infections.

Funding

None.

Seasonality and geographical distribution of Kawasaki disease among Black children in the Southeast United States

Introduction

Kawasaki Disease (KD) is a leading cause of pediatric acquired heart disease in the United States, affecting up to 7,000 children annually. Seasonal variation, an epidemiological characteristic of KD, has previously been reported predominantly among Asian children; however, little is known about the epidemiology and seasonality of KD of Black children within the U.S.

Methods

Electronic medical records were abstracted from 529 hospitalized KD patients admitted to a single tertiary center in Alabama between 2005 and 2019. Medical charts were reviewed to confirm KD diagnosis following American Heart Association criteria. Cases were stratified by the month of diagnosis date to assess seasonality, and statewide distribution of incidence is reported at county level using geographical spatial analysis. Comparisons were performed between Black patients and White patients with KD.

Results

The average number of KD cases per year was 35. Approximately, 60% were males and 44% were White children (N = 234), 45% were Black children (N = 240) and 11% were other races (N = 55). Black children were younger than White children at KD admission (median age 32 vs. 41 months respectively, p = 0.02). Overall, the highest rates of cases occurred between January and April. When stratifying by race, cases started to rise in December among White children with the highest rates between February and April with a peak in March. Among Black children cases were high during the winter season (January-April) with a peak in April. Similarly high rates also occurred in June, July and November. There were no differences in geographical distribution of cases by race.

Conclusion

KD incidence among White children in Alabama follows a seasonal cycle similar to other regions in the U.S. However, sustained incidence and additional peaks outside of the usual KD seasonality were seen among Black children with KD. Further studies are needed to investigate differential triggers between races.

Exploring the diagnostic value of eosinophil-to-lymphocyte ratio to differentiate Kawasaki disease from other febrile diseases based on clinical prediction model

Kawasaki disease (KD) is a febrile disease that affects children under 5 years of age and leads to serious cardiovascular complications such as coronary artery disease. The development of markers that can predict early is important to reduce the under- and misdiagnosis of KD. The aim of this research was to develop a diagnostic predictive model to differentiate Kawasaki disease (KD) from other febrile diseases using eosinophil-to-lymphocyte ratio (ELR) and other biomarkers. We recruited a total of 190 children with KD and 1604 children with other febrile diseases. We retrospectively collected clinical information from the children, which included laboratory data on the day of admission, such as white blood cells (WBC), hemoglobin (HGB), calcitoninogen (PCT), hypersensitive c-reactive protein (CRP), snake prognostic nutritional index (PNI), peripheral blood neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), and ELR. We performed analyses using univariate analysis, multivariate logistic regression, and column line plots, and evaluated the diagnostic parameters of the predictive models. ELR was significantly increased in patients with KD. After multivariate logistic regression, WBC, HGB, CRP, NLR, ELR and PNI were finally included as indicators for constructing the prediction model. The ROC curve analysis suggested that the C-index of the diagnostic prediction model was 0.921. The calibration curve showed good diagnostic performance of the columnar graph model. The cut-off value of ELR alone for KD was 0.04, the area under the ROC curve was 0.809. Kids with KD show highly expressive level of ELR compared to children with febrile disease, which can be used to diagnose KD, and column line graphs constructed together with other indicators can help pediatricians to identify KD more effectively from febrile children.

Bridging a diagnostic Kawasaki disease classifier from a microarray platform to a qRT-PCR assay

BACKGROUND

Kawasaki disease (KD) is a systemic vasculitis that mainly affects children under 5 years of age. Up to 30% of patients develop coronary artery abnormalities, which are reduced with early treatment. Timely diagnosis of KD is challenging but may become more straightforward with the recent discovery of a whole-blood host response classifier that discriminates KD patients from patients with other febrile conditions. Here, we bridged this microarray-based classifier to a clinically applicable quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay: the Kawasaki Disease Gene Expression Profiling (KiDs-GEP) classifier.

METHODS

We designed and optimized a qRT-PCR assay and applied it to a subset of samples previously used for the classifier discovery to reweight the original classifier.

RESULTS

The performance of the KiDs-GEP classifier was comparable to the original classifier with a cross-validated area under the ROC curve of 0.964 [95% CI: 0.924-1.00] vs 0.992 [95% CI: 0.978-1.00], respectively. Both classifiers demonstrated similar trends over various disease conditions, with the clearest distinction between individuals diagnosed with KD vs viral infections.

CONCLUSION

We successfully bridged the microarray-based classifier into the KiDs-GEP classifier, a more rapid and more cost-efficient qRT-PCR assay, bringing a diagnostic test for KD closer to the hospital clinical laboratory.

IMPACT

A diagnostic test is needed for Kawasaki disease and is currently not available. We describe the development of a One-Step multiplex qRT-PCR assay and the subsequent modification (i.e., bridging) of the microarray-based host response classifier previously described by Wright et al. The bridged KiDs-GEP classifier performs well in discriminating Kawasaki disease patients from febrile controls. This host response clinical test for Kawasaki disease can be adapted to the hospital clinical laboratory.

Research trends on causes of Kawasaki disease in the COVID-19 era: focus on viral infections

Despite studies on the etiology of Kawasaki disease (KD) ongoing for half a century since its discovery, its cause has not yet been clearly identified. Although the clinical, epidemiological, and pathophysiological characteristics of KD are presumed to be closely related to infectious diseases, studies of various pathogens to identify its etiology have been actively conducted. To date, bacteria, fungi, and viruses have been investigated to determine the relationship between KD and infection, among which viruses have attracted the most attention. In particular, during the coronavirus disease 2019 pandemic, there were many reports in Europe of a sharp increase in cases of Kawasaki-like disease (KLD), while conflicting reports that the prevalence of KD decreased due to thorough "social distancing" or "wearing mask" in Asian countries drew more attention regarding the association between KD and viral infection. Therefore, the differential diagnosis of KD from KLD with these similar spectra has become a very important issue; simultaneously, research to solve questions about the association between KD and viral infections, including sudden acute respiratory syndrome coronavirus 2, is drawing attention again. Moreover, a new concept has emerged that immune responses occurring in patients with KD can be caused by the pathogen itself as well as host cells damaged by infection. This paper summarizes the research trends into KD etiology and related pathophysiology, especially its association with viral infections, and present future research tasks to increase our understanding of KD.

Profile of Children with Kawasaki Disease Associated with Tropical Infections

OBJECTIVE

To describe various infectious triggers for Kawasaki disease (KD) in India.

METHODS

A series of 10 children with diagnosed infections who developed KD during their course of illness has been presented. They were diagnosed by the American Heart Association (AHA) 2017 guidelines. Echocardiography was done to check for coronary artery dilation. Treatment was instituted as per standard protocol.

RESULTS

Kawasaki disease was diagnosed in 8 boys and 2 girls, aged 1 mo to 11 y. These children were being treated for dengue, chikungunya, SARS-CoV-2, hepatitis A, tuberculosis, brucellosis, disseminated staphylococcal sepsis, scrub typhus, and enteric fever.

CONCLUSIONS

Kawasaki disease has been associated with infectious triggers. It should be considered in febrile patients with mucocutaneous involvement or in nonresponsive sepsis, despite adequate therapy.

Pharmacologic interventions for Kawasaki disease in children: A network meta-analysis of 56 randomized controlled trials

Background

Although the current consensus recommends a standard treatment of high-dose intravenous immunoglobulin with high-dose aspirin to manage Kawasaki disease (KD), the use of different adjunctive therapies remains controversial. The aim of the current network meta-analysis (NMA) was to compare the efficacy and tolerability of different existing interventions for the initial and refractory stages of KD.

Methods

An NMA of randomised controlled trials (RCTs) was conducted using the frequentist model applied after electronic searches in PubMed, Embase, ScienceDirect, ProQuest, ClinicalTrials.gov, ClinicalKey, Cochrane CENTRAL, and Web of Science. The main outcomes were reduced fever duration/diminished severity of fever subsided. The initial stage of KD was defined as the first stage to treat patients with KD; the refractory stage of KD represents KD patients who failed to respond to standard KD treatment. The cut-off points for intravenous immunoglobulin (IVIG) were low (100–400 mg), medium (1 g), and high (at least 2 g).

Findings

A total of fifty-six RCTs with 6486 participants were included. NMA demonstrated that the medium-dosage IVIG + aspirin + infliximab [mean difference=−1.76 days (95% confidence intervals (95% CIs): −3.65 to 0.13 days) compared to high-dosage IVIG + aspirin] exhibited the shortest fever duration; likewise, the medium-dosage IVIG + aspirin + infliximab [odds ratio (OR)=0.50, 95% CIs: 0.18–1.37 compared to high-dosage IVIG + aspirin] exhibited the smallest incidence of coronary artery lesion (CAL) in the initial-stage KD. In the refractory-stage KD, the high-dosage IVIG + pulse steroid therapy (OR=0.04, 95% CIs: 0.00–0.43 compared to the high-dosage IVIG only) had the best rate of decline of fever; likewise, the high-dosage IVIG + ciclosporin [OR=0.05 (95% CIs: 0.00–1.21) compared to the high-dosage IVIG only] exhibited the smallest incidence of CAL. Infliximab significantly improved resolution compared to the high-dosage IVIG only group (OR=0.20, 95%CIs: 0.07–0.62) in refractory-stage KD.

Interpretation

The NMA demonstrated that the combination therapy with the standard therapy of IVIG and aspirin might have an additional effect on shortening the duration of fever and lowering the CAL incidence rate in patients with acute KD. Moreover, the combination therapy with high-dose IVIG and pulse steroid therapy or cyclosporine therapy might have an additional effect on improving the rate of decline of fever and lowering the incidence rate of CAL in children with refractory KD. Because some of the findings of this NMA should be considered hypothesis-generating rather than confirmatory, further evidence from de novo randomised trials is needed to support our results.

Funding

None.

A Review of Coronaviruses Associated With Kawasaki Disease: Possible Implications for Pathogenesis of the Multisystem Inflammatory Syndrome Associated With COVID-19

Multisystem Inflammatory Syndrome in Children (MIS-C), representing a new entity in the spectrum of manifestations of COVID-19, bears symptomatic resemblance with Kawasaki Disease (KD). This review explores the possible associations between KD and the human coronaviruses and discusses the pathophysiological similarities between KD and MIS-C and proposes implications for the pathogenesis of MIS-C in COVID-19. Since 2005, when a case-control study demonstrated the association of a strain of human coronavirus with KD, several studies have provided evidence regarding the association of different strains of the human coronaviruses with KD. Thus, the emergence of the KD-like disease MIS-C in COVID-19 may not be an unprecedented phenomenon. KD and MIS-C share a range of similarities in pathophysiology and possibly even genetics. Both share features of a cytokine storm, leading to a systemic inflammatory response and oxidative stress that may cause vasculitis and precipitate multi-organ failure. Moreover, antibody-dependent enhancement, a phenomenon demonstrated in previous coronaviruses, and the possible superantigenic behavior of SARS-CoV-2, possibly may also contribute toward the pathogenesis of MIS-C. Lastly, there is some evidence of complement-mediated microvascular injury in COVID-19, as well as of endotheliitis. Genetics may also represent a possible link between MIS-C and KD, with variations in FcγRII and IL-6 genes potentially increasing susceptibility to both conditions. Early detection and treatment are essential for the management of MIS-C in COVID-19. By highlighting the potential pathophysiological mechanisms that contribute to MIS-C, our review holds important implications for diagnostics, management, and further research of this rare manifestation of COVID-19.

Kawasaki Disease Shock Syndrome vs Classical Kawasaki Disease: A Meta-analysis and Comparison With SARS-CoV-2 Multisystem Inflammatory Syndrome

BACKGROUND

The emergence of increasing reports worldwide of a severe inflammatory process and shock in pediatric patients resembling Kawasaki disease (KD)-and, more specifically, Kawasaki disease shock syndrome (KDSS)-prompted us to explore KDSS in a preamble of a systematic comparison between the 2 conditions.

METHODS

We completed a systematic review of KDSS and performed a meta-analysis comparison between reported KDSS cases and KD controls.

RESULTS

A total of 10 case-control series were included in the meta-analysis. Patients with KDSS were older (38.4 ± 30.6 vs 21.9 ± 19.5 months; P < 0.001) compared with standard KD with equal sex distribution and completeness of clinical diagnostic criteria. KDSS present higher C-reactive protein (59.4 ± 29.2 mg/dL vs 20.8 ± 14.8 mg/dL; P < 0.001), lower albumin (2.7 ± 0.5 g/dL vs 3.3 ± 0.5 g/dL; P < 0.01), and lower platelets (255 ± 149 109/L vs 394 ± 132 109/L; P < 0.001) but only borderline higher white blood cells (P = 0.06). Differences in alanine transaminase, aspartate aminotransferase, and erythrocyte sedimentation rate were nonsignificant. The odds of intravenous immunoglobulin resistance (44.4% vs 9.6%; (P < 0.001) and the hospital length of stay (10.9 ± 5.8 vs 5.0 ± 3.0 days; P < 0.001) were higher in KDSS, as were the odds of coronary-artery abnormalities (33.9% vs 8.6%; P < 0.001).

CONCLUSIONS

This first meta-analysis on KDSS vs KD represents a basis for future works on KDSS and opens the opportunity for future multicentre studies in the search of causal relationships between presenting elements and the eventual complications of KDSS. The similarities between SARS-CoV-2 multisystem inflammatory syndrome in children and KDSS open new horizons to the understanding of the etiology and pathophysiology related to KDSS.

Kawasaki Disease Patient Stratification and Pathway Analysis Based on Host Transcriptomic and Proteomic Profiles

The aetiology of Kawasaki disease (KD), an acute inflammatory disorder of childhood, remains unknown despite various triggers of KD having been proposed. Host 'omic profiles offer insights into the host response to infection and inflammation, with the interrogation of multiple 'omic levels in parallel providing a more comprehensive picture. We used differential abundance analysis, pathway analysis, clustering, and classification techniques to explore whether the host response in KD is more similar to the response to bacterial or viral infections at the transcriptomic and proteomic levels through comparison of 'omic profiles from children with KD to those with bacterial and viral infections. Pathways activated in patients with KD included those involved in anti-viral and anti-bacterial responses. Unsupervised clustering showed that the majority of KD patients clustered with bacterial patients on both 'omic levels, whilst application of diagnostic signatures specific for bacterial and viral infections revealed that many transcriptomic KD samples had low probabilities of having bacterial or viral infections, suggesting that KD may be triggered by a different process not typical of either common bacterial or viral infections. Clustering based on the transcriptomic and proteomic responses during KD revealed three clusters of KD patients on both 'omic levels, suggesting heterogeneity within the inflammatory response during KD. The observed heterogeneity may reflect differences in the host response to a common trigger, or variation dependent on different triggers of the condition.

Update on molecular diversity and multipathogenicity of staphylococcal superantigen toxins

Staphylococcal superantigen (SAg) toxins are the most notable virulence factors associated with Staphylococcus aureus, which is a pathogen associated with serious community and hospital acquired infections in humans and various diseases in animals. Recently, SAg toxins have become a superfamily with 29 types, including staphylococcal enterotoxins (SEs) with emetic activity, SE-like toxins (SEls) that do not induce emesis in primate models or have yet not  been tested, and toxic shock syndrome toxin-1 (TSST-1). SEs and SEls can be subdivided into classical types (SEA to SEE) and novel types (SEG to SElY, SE01, SE02, SEl26 and SEl27). The genes of SAg toxins are located in diverse accessory genetic elements and share certain structural and biological properties. SAg toxins are heat-stable proteins that exhibit pyrogenicity, superantigenicity and capacity to induce lethal hypersensitivity to endotoxin in humans and animals. They have multiple pathogenicities that can interfere with normal immune function of host, increase the chances of survival and transmission of pathogenic bacteria in host, consequently contribute to the occurrence and development of various infections, persistent infections or food poisoning. This review focuses on the following aspects of SAg toxins: (1) superfamily members of classic and novelty discovered staphylococcal SAgs; (2) diversity of gene locations and molecular structural characteristics; (3) biological characteristics and activities; (4) multi-pathogenicity of SAgs in animal and human diseases, including bovine mastitis, swine sepsis, abscesses and skin edema in pig, arthritis and septicemia in poultry, and nosocomial infections and food-borne diseases in humans.

An Update on Cardiovascular Risk Factors After Kawasaki Disease

First described in Japan 50 years ago, Kawasaki disease is a worldwide multisystem disease. It is an acute self-limited vasculitis of unknown etiology that can lead to coronary artery lesions, such as dilatation, aneurysms, and stenosis in children. It is one of the common causes of acquired heart disease among children in developed countries. The coronary aneurysm is a severe complication in the acute stage, possibly leading to stenotic lesions or myocardial ischemia. More concerns have centered on endothelial damage and the early onset of atherosclerosis in patients with KD. Although the coronary artery aneurysm is small or degenerated, the vascular structure does not return to normal, vascular endothelial dysfunction and remodeling continue. Most patients diagnosed with coronary artery sequelae are at risk of long-term complications. There are still many unknown aspects regarding the long-term prognosis of patients. Concerns have centered on the early onset of atherosclerosis in patients with KD. There is still no consensus on the relationship between Kawasaki disease and atherosclerosis. This study aimed to evaluate if patients with a history of KD were at risk of accelerated atherosclerosis.

Neither soyfoods nor isoflavones warrant classification as endocrine disruptors: a technical review of the observational and clinical data

Soybeans are a rich source of isoflavones, which are classified as phytoestrogens. Despite numerous proposed benefits, isoflavones are often classified as endocrine disruptors, based primarily on animal studies. However, there are ample human data regarding the health effects of isoflavones. We conducted a technical review, systematically searching Medline, EMBASE, and the Cochrane Library (from inception through January 2021). We included clinical studies, observational studies, and systematic reviews and meta-analyses (SRMA) that examined the relationship between soy and/or isoflavone intake and endocrine-related endpoints. 417 reports (229 observational studies, 157 clinical studies and 32 SRMAs) met our eligibility criteria. The available evidence indicates that isoflavone intake does not adversely affect thyroid function. Adverse effects are also not seen on breast or endometrial tissue or estrogen levels in women, or testosterone or estrogen levels, or sperm or semen parameters in men. Although menstrual cycle length may be slightly increased, ovulation is not prevented. Limited insight could be gained about possible impacts of in utero isoflavone exposure, but the existing data are reassuring. Adverse effects of isoflavone intake were not identified in children, but limited research has been conducted. After extensive review, the evidence does not support classifying isoflavones as endocrine disruptors.

Leukocyte proteomics coupled with serum metabolomics identifies novel biomarkers and abnormal amino acid metabolism in Kawasaki disease

Kawasaki disease (KD) is a systemic vasculitis that can lead to severe cardiovascular complications, whereas the development and clinical usage of specific biomarkers might help diagnose KD and avoid certain complications. To this end, the molecular profiles of acute KD patients with coronary artery lesions (CAL) were first investigated through leukocyte proteomics and serum metabolomics assays. A total of 269 differentially abundant proteins and 35 differentially abundant metabolites with the top fold-changed levels were identified in acute KD patients compared to those in the healthy controls. Among them, several highly promising candidate marker proteins and metabolites indicative of KD progression were further analysed, such as the increased proteins ALPL, NAMPT, and S100P, as well as the decreased proteins C1QB and apolipoprotein family members. Moreover, metabolites, including succinic acid, dGMP, hyaluronic acid, L-tryptophan, propionylcarnitine, inosine, and phosphorylcholine, were found to be highly accurate at distinguishing between KD patients and healthy controls. Interestingly, the abnormal expression levels of a distinct set of proteins and metabolites in acute KD patients can be restored to normal levels upon intravenous immunoglobulin (IVIG) treatment. Overall, this work has revealed novel biomarkers and abnormal amino-acid metabolism as a prominent feature involved in KD patients with CAL. SIGNIFICANCE: KD is frequently concomitant with the development of life-threatening coronary vasculitis. Here, the profiles of leukocyte proteomics and serum metabolomics in acute KD patients with CALs were first investigated, and several hub molecules identified here could be used as supplemental biomarkers for KD diagnosis. Moreover, the metabolomic abnormalities especially the amino acids are particularly prominent in KD patients. Interestingly, the abnormal expression levels of a distinct set of proteins and metabolites in acute KD patients can be restored to normal levels upon IVIG treatment. Therefore, these findings might help understand the IVIG activities and also the underlying mechanisms of IVIG-resistant patients, thereby providing a new perspective for the exploration of mechanisms related to KD.

Higher efficacy of infliximab than immunoglobulin on Kawasaki disease, a meta-analysis

This meta-analysis evaluated the efficacy and safety of infliximab as initial therapy for patients with Kawasaki disease (KD) and intravenous immunoglobulin (IVIG) resistant KD. Studies of infliximab in KD, published between January 2004 and December 2019, were curated from PubMed, MEDLINE, and Cochrane Library. Data were analyzed using STATA Version 12.0. Of the 8 studies considered, 4 evaluated the effect of infliximab combined with IVIG as primary therapy in KD, and the remaining investigated the effect of infliximab in IVIG resistant patients. Infliximab was more effective than the control group, with the total summary odds ratio (OR) of 0.34 (95% confidence interval (CI): 0.19-0.62). The treatment resistance of the infliximab group was lower than the IVIG group (0.36 [95% CI: 0.14-0.92]) when infliximab was combined with IVIG as the initial treatment. However, infliximab treatment for IVIG resistant KD was more effective than the IVIG group (0.28 [95% CI: 0.12-0.66]). There was no significant increase in the incidence of coronary artery lesions. The total summary OR for the incidence of coronary artery lesions and infliximab treatment was 0.88 (95% CI: 0.48-1.62). There was no statistically significant difference in adverse events (AEs) when compared between the groups (0.71 [95% CI: 0.44-1.16]). Infliximab combined with IVIG reduced treatment resistance in KD patients vs. conventional IVIG therapy. Infliximab improved clinical course in IVIG resistant KD patients. Infliximab treatment did not reduce the incidence of coronary artery lesions and did not show any significant increase in the incidence of AEs. PROSPERO REGISTRATION NUMBER: CRD42020218554.

Increased Risk of Kawasaki Disease in Infants Born of Mothers With Immune Disorders

Introduction: Genetic susceptibility and immune dysregulation play important roles in the pathogenesis of Kawasaki disease (KD). However, it is still unclear whether KD causes immune disorder later in life or whether inherited susceptibility to immune disorders causes KD. The aim of this study was to elucidate whether inherited immune disease properties from mothers increase the risk of KD from a population-based perspective. Method: Taiwan's National Health Insurance Research Database was the main data source in this study. Parents and children were linked using the Taiwan Maternal and Child Health Database. Patients diagnosed with KD and younger than 18 years from 2004 to 2015 were enrolled as the study population. The control group was randomly selected from individuals without the diagnosis of KD matched by age, index year, sex, and urbanization level at a ratio of 1 to 10. The prevalence of maternal autoimmune and allergic diseases was compared between groups. Results: In total, 7,178 children were found to have been diagnosed with Kawasaki disease. Then 71,780 children matched by index year, gender, and urbanization were randomly selected to serve as the control group. Children born from mothers with asthma and allergic rhinitis had a higher risk of developing KD. Children of mothers with an autoimmune disorder had a significantly increased tendency to develop KD. Maternal numbers of autoimmune disorders showed a dose-dependent relationship with KD incidence. Conclusion: This is the first population-based study to investigate maternal immune diseases and the risk of KD in their children. Children of mothers with immune disorders tend to have a higher risk of KD.

Kawasaki disease seasonality in Venezuela supports an arbovirus infection trigger

Kawasaki disease (KD) is an inflammatory disease primarily affecting infants and young children, whose etiology remains uncertain. Observational studies of the overlap between KD outbreaks and seasonal peaks of arboviral infections, suggest the possible role of these pathogens as triggers of KD. In Venezuela, regions with the highest reported arboviral infections simultaneously have the highest incidence of KD. One proposed explanation for this association involves the role of proinflammatory mediators, interleukin-1 (IL-1), IL-6, tumor necrosis factor, and vascular endothelial growth factor as mediators of coronary endothelial damage. The promotion of inflammation and tissue destruction by these cytokines is thought to contribute to the coronary endothelial damage experienced in KD. The utilization of overlapping KD and arboviral infection trends contribute to the comprehension of KD etiology, with improvements in diagnosis, prognosis and treatment.

False-positive SARS-CoV-2 serology in 3 children with Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is an acute febrile and eruptive disease with systemic vasculitis predominantly affecting young East Asian children. Recent reports showed that children with KD-like disease from KD low prevalence regions had positive SARS-CoV-2 serology despite a negative SARS-CoV-2 polymerase chain reaction (PCR) in respiratory samples.

OBJECTIVES

To describe 3 pediatric Kawasaki Disease patients with false positive SARS-CoV-2 serology.

STUDY DESIGN

We retrospectively recruited children with KD diagnosed during the COVID-19 outbreak in Hong Kong. Clinical characteristics and laboratory test results including SARS-CoV-2 PCR results were retrieved. We performed a microparticle-based immunoassay for the detection of IgG against nucleoprotein (NP) and spike protein receptor binding domain (RBD), and a microneutralization assay for the detection of neutralizing antibodies.

RESULTS

Three Chinese children with typical KD were identified. They had no epidemiological links with COVID-19 patients and tested negative for SARS-CoV-2 NPA PCR. They were treated with IVIG and aspirin, and were discharged without complications. Subsequently 2 of them were tested positive against anti-RBD and anti-NP antibodies and 1 was tested positive against anti- RBD antibodies. However, microneutralization assay showed that neutralizing antibodies were absent, suggesting a false-positive IgG result.

CONCLUSION

Detection of neutralizing antibodies is recommended to confirm previous SARS-CoV-2 infection in IgG-positive but PCR-negative patients.

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.

Altered gut microbiota correlated with systemic inflammation in children with Kawasaki disease

Kawasaki disease (KD) is a multi-systemic vasculitis of unknown etiology that occurs mainly in children, and the disturbance of gut microbiota is generally believed to cause a hyperimmune reaction triggering KD. The aim of the study was to investigate the alterations in the fecal microbiota and assess its relationship with systemic inflammation. Totally 30 KD children were enrolled and followed up for 6 months, with another group of 30 age- and sex-matched healthy children as controls. Phylotype profiles of fecal microbial communities were analyzed using 16S rRNA gene sequencing. Serum inflammatory markers were detected by flow cytometer. We showed that KD children exhibited a significant reduction in fecal microbial diversity in the acute phase compared with the healthy controls. Enterococcus, Acinetobacter, Helicobacter, Lactococcus, Staphylococcus and Butyricimonas in acute KD children were significantly higher than the healthy children. Levels of systemic inflammation biomarkers, including IL-2, IL-4, IL-6, IL-10, TNF-α, and INF-γ, were significantly elevated in the acute KD children. Altered microbiota genera Enterococcus and Helicobacter abundances were shown to be correlated positively with IL-6, which were never previously reported in KD. This study suggested that gut microbiota alteration is closely associated with systemic inflammation, which provides a new perspective on the etiology and pathogenesis of KD.

Increased Interleukin-35 suppresses peripheral CD14+ monocytes function in patients with Kawasaki disease

Background

Interleukin-35 (IL-35) is a newly identified IL-12 cytokine family member, which regulates the activity of immune cells in infectious diseases and autoimmune disorders. However, the regulatory function of IL-35 in Kawasaki disease is not well elucidated.

Methods

Thirty-three patients with Kawasaki disease and seventeen healthy controls were studied. Peripheral IL-35 concentration was measured by enzyme linked immunosorbent assay. CD14⁺ monocytes were purified, and mRNA expression of IL-35 receptor (IL-12Rβ2 and gp130) was semi-quantified by real-time polymerase chain reaction. CD14⁺ monocytes were stimulated with recombinant IL-35. The modulatory role of IL-35 treated CD14⁺ monocytes to naïve CD4⁺ T cell activation was investigated by flow cytometry. The influence of IL-35 to cytotoxicity of CD14⁺ monocytes was assessed by measuring target cell death, cytokine and granzyme secretion.

Results

Plasma IL-35 concentration was elevated in patients with Kawasaki disease. There was no significant differences of either IL-12Rβ2 or gp130 mRNA expression in CD14⁺ monocytes between Kawasaki disease patients and controls. IL-35 suppressed CD14⁺ monocytes induced naïve CD4⁺ T cell activation in Kawasaki disease, and this process required direct cell-to-cell contact. IL-35 also inhibited tumor necrosis factor-α and granzyme B secretion by CD14⁺ monocytes from patients with Kawasaki disease, however, only granzyme B was responsible for the cytotoxicity of CD14⁺ monocytes.

Conclusions

IL-35 played an important immunosuppressive role to CD14⁺ monocytes function in Kawasaki disease.

Kawasaki Disease Following Severe Sunburn Injury

Background: Although an etiology of Kawasaki disease (KD) is unknown, an aberrant innate immune system in predisposed individuals has been proposed to play a key role in the development of KD vasculitis. Various etiological pathogens have been proposed as the trigger of KD and a scaled injury preceding symptom onset has been reported as one of them. Here, we report a 17-month-old Japanese female who was hospitalized due to high fever lasting for 4 days with infection ruled out as a cause. On admission, she displayed severe sunburn all over her body following a prolonged period of outdoor play 5 days ago. On the 5 day of illness, she developed complete KD. Serum levels of high mobility group box 1, a representative for damage-associated molecular patterns (DAMPs), were elevated during acute phase and continued to decrease during subacute phase. This unique course suggested the inflammatory process of KD involving innate immunity via DAMPs.

Global Investigation of Immune Repertoire Suggests Kawasaki Disease Has Infectious Cause

BACKGROUND

Kawasaki disease (KD) severely threatens young children's health worldwide. The pathogenic mechanism of KD has not yet been solved, so there is still debate over whether KD is an infectious disease or an autoimmune disease.Methods and Results:To solve this problem, an immune repertoire analysis of KD was conducted. We collected blood cell RNA samples and prepared them into amplicons with iRepertoire kits. The amplicons were sequenced and analyzed with the iRepertoire pipeline. We first identified KD-specific VJ and VDJ forms that had the potential to serve as biomarkers of KD. In addition, the KD-specific VDJ forms were contributed mostly by immunoglobulin G. The D50 value analysis showed that B-cell diversity in KD is decreased, suggesting unique immunoglobulins are produced in KD. Moreover, V, D and J segment usage in IgA, IgG and IgM was consistent with previous KD studies. Further comparison showed no difference in CDR3 peptide length between KD and fever controls (subjects with fever but not diagnosed as KD), indicting KD had B-cell selection phenomenon that has a non-autoimmune pattern. The comparison of amino acid usage of the CDR3 region demonstrated a preference for hydrophilic amino acids in KD.

CONCLUSIONS

The results of D50 value, VDJ usage and CDR3 peptide length analyses suggested the characteristics of infectious disease for KD.