Perspective of Immunopathogenesis and Immunotherapies for Kawasaki Disease

Development of an immunoinflammatory indicator-related dynamic nomogram based on machine learning for the prediction of intravenous immunoglobulin-resistant Kawasaki disease patients

BACKGROUND

Approximately 10-20% of Kawasaki disease (KD) patients suffer from intravenous immunoglobulin (IVIG) resistance, placing them at higher risk of developing coronary artery aneurysms. Therefore, we aimed to construct an IVIG resistance prediction tool for children with KD in Shanghai, China.

METHODS

Retrospective analysis was conducted on data from 1271 patients diagnosed with KD and the patients were randomly divided into a training set and a validation set in a 2:1 ratio. Machine learning algorithms were employed to identify important predictors associated with IVIG resistance and to build a predictive model. The best-performing model was used to construct a dynamic nomogram. Moreover, receiver operating characteristic curves, calibration plots, and decision-curve analysis were utilized to measure the discriminatory power, accuracy, and clinical utility of the nomogram.

RESULTS

Six variables were identified as important predictors, including C-reactive protein, neutrophil ratio, procalcitonin, CD3 ratio, CD19 count, and IgM level. A dynamic nomogram constructed with these factors was available at https://hktk.shinyapps.io/dynnomapp/. The nomogram demonstrated good diagnostic performance in the training and validation sets (area under the receiver operating characteristic curve = 0.816 and 0.800, respectively). Moreover, the calibration curves and decision curves analysis indicated that the nomogram showed good consistency between predicted and actual outcomes and had good clinical benefits.

CONCLUSION

A web-based dynamic nomogram for IVIG resistance was constructed with good predictive performance, which can be used as a practical approach for early screening to assist physicians in personalizing the treatment of KD patients in Shanghai.

Coronary artery lesions in children with Kawasaki disease: status quo and nursing care

Aim

Coronary artery lesion (CAL) is a common yet serious complication in children with Kawasaki disease. The aim of the present study was to evaluate the influencing factors of CAL in children with Kawasaki disease, to provide reference for the clinical treatment and care of children with Kawasaki disease.

Design

A retrospective cohort study.

Methods

Children with Kawasaki disease treated in a tertiary hospital in China between 1 January 2021 and 31 December 2022 were selected. The characteristics and clinical data of children with Kawasaki disease were analyzed. Spearman's correlation analysis was conducted to evaluate the relationship between CAL and the characteristics of children with Kawasaki disease. A logistic regression analysis was used to analyze the influencing factors of CAL in children with Kawasaki disease.

Results

In total, 185 children with Kawasaki disease were included; the incidence of CAL in children with Kawasaki disease was 18.38%. Pearson's correlation analysis showed that gender (r = 0.504), age (r = 0.611), duration of fever ≥10 days (r = 0.579), hemoglobin (Hb) (r = 0.623), and C-reactive protein (CRP) (r = 0.558) were all correlated with the CAL in children with Kawasaki disease (all p < 0.05). Logistic regression analyses showed that male [odds ratio (OR) = 2.543, 95% confidence interval (CI): 1.801-3.077, p = 0.040], age ≤2 years (OR = 3.002, 95% CI: 2.744-3.641, p = 0.012), duration of fever ≥10 days (OR = 2.089, 95% CI: 1.624-2.515, p = 0.028), Hb ≤105 g/L (OR = 1.914, 95% CI: 1.431-2.406, p = 0.013), and CRP ≥100 mg/L (OR = 2.168, 95% CI: 1.893-2.531, p = 0.035) were the risk factors of CAL in children with Kawasaki disease (all p < 0.05).

Conclusions

The incidence of CAL in children with Kawasaki disease is high and there are many related risk factors. Clinical medical workers should take early warning and carry out interventions and nursing care according to these risk factors to improve the prognosis of children with Kawasaki disease.

Multi-ancestry genetic analysis of gene regulation in coronary arteries prioritizes disease risk loci

Genome-wide association studies (GWASs) have identified hundreds of risk loci for coronary artery disease (CAD). However, non-European populations are underrepresented in GWASs, and the causal gene-regulatory mechanisms of these risk loci during atherosclerosis remain unclear. We incorporated local ancestry and haplotypes to identify quantitative trait loci for expression (eQTLs) and splicing (sQTLs) in coronary arteries from 138 ancestrally diverse Americans. Of 2,132 eQTL-associated genes (eGenes), 47% were previously unreported in coronary artery; 19% exhibited cell-type-specific expression. Colocalization revealed subgroups of eGenes unique to CAD and blood pressure GWAS. Fine-mapping highlighted additional eGenes, including TBX20 and IL5. We also identified sQTLs for 1,690 genes, among which TOR1AIP1 and ULK3 sQTLs demonstrated the importance of evaluating splicing to accurately identify disease-relevant isoform expression. Our work provides a patient-derived coronary artery eQTL resource and exemplifies the need for diverse study populations and multifaceted approaches to characterize gene regulation in disease processes.

Early Clinical Evaluation of Coronary Artery Lesions in Kawasaki Disease

The purpose of this study is to analyze the early clinical features of coronary artery lesion (CAL) in Kawasaki disease (KD), evaluate systemic inflammation indicators, and enhance early recognition of CAL in the acute phase of KD. A total of 314 children with KD were divided into those with CAL (CAL group) and without CAL (NCAL group) using echocardiographic results, and their clinical data were retrospectively analyzed. For KD patients, male, children aged 3 to 9 years, and those with fever longer than 6 days before intravenous immunoglobulin (IVIG) use were more likely to have CAL. There were significant differences in sex, age, and fever time (P < .05). Moreover, some laboratory indicator test results revealed there was a significant difference between N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and interleukin-6 (IL-6), and the CAL (P < .05). This study has certain guiding significance for early clinical evaluation.

Roles of Oxidative Injury and Nitric Oxide System Derangements in Kawasaki Disease Pathogenesis: A Systematic Review

Kawasaki disease (KD) is an acute febrile vasculitis that occurs mostly in children younger than five years. KD involves multiple intricately connected inflammatory reactions activated by a cytokine cascade. Despite therapeutic advances, coronary artery damage may develop in some patients, who will be at risk of clinical cardiovascular events and even sudden death. The etiology of KD remains unclear; however, it may involve both genetic and environmental factors leading to aberrant inflammatory responses. Given the young age of onset, prenatal or perinatal exposure may be etiologically relevant. Multisystem inflammatory syndrome in children, a post-infectious hyper-inflammatory disorder associated with severe acute respiratory syndrome coronavirus 2, has features that overlap with those of KD. Available evidence indicates that vascular endothelial dysfunction is a critical step in the sequence of events leading to the development of cardiovascular lesions in KD. Oxidative stress and the dysregulation of the nitric oxide (NO) system contribute to the pathogenesis of inflammatory responses related to this disease. This review provides current evidence and concepts highlighting the adverse effects of oxidative injury and NO system derangements on the initiation and progression of KD and potential therapeutic strategies for cardiovascular pathologies in affected children.

Anti-Inflammatory and Immunomodulatory Effect of High-Dose Immunoglobulins in Children: From Approved Indications to Off-Label Use

BACKGROUND

The large-scale utilization of immunoglobulins in patients with inborn errors of immunity (IEIs) since 1952 prompted the discovery of their key role at high doses as immunomodulatory and anti-inflammatory therapy, in the treatment of IEI-related immune dysregulation disorders, according to labelled and off-label indications. Recent years have been dominated by a progressive imbalance between the gradual but constant increase in the use of immunoglobulins and their availability, exacerbated by the SARS-CoV-2 pandemic.

OBJECTIVES

To provide pragmatic indications for a need-based application of high-dose immunoglobulins in the pediatric context.

SOURCES

A literature search was performed using PubMed, from inception until 1st August 2023, including the following keywords: anti-inflammatory; children; high dose gammaglobulin; high dose immunoglobulin; immune dysregulation; immunomodulation; immunomodulatory; inflammation; intravenous gammaglobulin; intravenous immunoglobulin; off-label; pediatric; subcutaneous gammaglobulin; subcutaneous immunoglobulin. All article types were considered.

IMPLICATIONS

In the light of the current imbalance between gammaglobulins' demand and availability, this review advocates the urgency of a more conscious utilization of this medical product, giving indications about benefits, risks, cost-effectiveness, and administration routes of high-dose immunoglobulins in children with hematologic, neurologic, and inflammatory immune dysregulation disorders, prompting further research towards a responsible employment of gammaglobulins and improving the therapeutical decisional process.

Epstein-Barr virus downregulates the α7 nicotinic acetylcholine receptor of CD8+ T lymphocytes might associate with coronary artery lesions in Kawasaki disease patients

OBJECTIVES

Kawasaki disease (KD) is a systemic vasculitis that is caused by immunological dysregulation in children exposed to pathogens like Epstein-Barr virus (EBV). Myocardial ischemia or infarction due to coronary artery lesions (CALs) might be lethal. However, it is unclear how pathogens, immunomodulation, and CALs interact, particularly in KD patients co-infected with the most widespread virus, EBV.

METHODS

We investigated pathogen carriage and fundamental clinical data in 281 KD patients. Immunological differences between CALs and non-CALs in KD patients under different conditions were analyzed. Then, the effect of infection by different pathogens on the immune response was excluded, and most EBV co-infected KD patients were included to assess the incidence of CALs, the level of immune modulation, and regulatory mechanisms in different EBV infection states.

RESULTS

Our results showed multiple pathogenic infections occur in KD patients, with EBV being the most prevalent. The incidence of CALs in the EBV-DNA (+) acute infection group, EBV-DNA (-) acute infection group, and EBV latent infection group was 0 (0/6), 27.27% (3/11) and 41.67% (10/24), respectively. The two groups were younger and had increased IL-6 levels and B cells, decreasing CD8+ T cells than the EBV-DNA (+) acute infection group. Interestingly, the increased B cells were not associated with immunoglobulin release. Additionally, these patients down-regulated α7 nicotinic acetylcholine receptor (α7nAChR) and downstream molecule PI3K/AKT/mTOR while activating the NF-κB.

CONCLUSION

Patients with different EBV infection statuses exhibit different incidences of CALs. In acute EBV-DNA (-) infected and latent EBV-infected patients, the number of CD8+ T cells decreased and downregulated CD8+ T cells' α7nAChR and PI3K/AKT/mTOR, which may associate with CALs, while the expression of NF-κB and the pro-inflammatory factor IL-6 was upregulated by inhibiting the anti-inflammatory molecule α7nAChR.

Serum IL-41 might be a biomarker for IVIG resistance and coronary artery lesions in Kawasaki disease

BACKGROUND

This study aimed to evaluate serum IL-41 levels in IVIG resistance and CALs, and to elucidate the relationship between IL-41 and Kawasaki disease (KD)-related clinical parameters.

METHODS

93 children with KD were collected. Baseline clinical data were obtained by physical examination. Serum IL-41 levels were detected with an enzyme-linked immunosorbent assay. The correlations between IL-41 and the clinical parameter of KD were performed by Spearman correlation coefficient. Receiver operating characteristic curve analysis was performed to assess the predictive ability of IL-41 for IVIG resistance and CALs.

RESULTS

Serum IL-41 levels were significantly increased in the IVIG resistance group compared with the response group, and serum IL-41 levels in the CALs group were higher than those in the non-CALs group. Serum IL-41 levels were positively correlated with erythrocyte sedimentation rate, C-reactive protein and C-reactive protein/albumin ratio, but negatively correlated with albumin. Serum IL-41 levels was an independent risk factor for CALs, and total fever days and neutrophil-to-lymphocyte ratio (NLR) were independent predictors for IVIG resistance. The area under the curve (AUC) value for serum IL-41 to predict IVIG resistance was 0.73, yielding a sensitivity of 54.55% and a specificity of 81.71%. The AUC of serum IL-41 was 0.712, with a sensitivity of 63.16% and a specificity of 72.97% for predicting CALs. IL-41 was not inferior to NLR in predicting IVIG resistance (z = 0.282, p = 0.7783).

CONCLUSIONS

Serum IL-41 was increased in IVIG resistance and CALs. Serum IL-41 might be a new potential biomarker for IVIG resistance and CALs.

LncRNAs in Kawasaki disease and Henoch-Schönlein purpura: mechanisms and clinical applications

Kawasaki disease (KD) and Henoch-Schönlein purpura (HSP) are the two most predominant types of childhood vasculitis. In childhood vasculitis, factors such as lack of sensitive diagnostic indicators and adverse effects of drug therapy may cause multiorgan system involvement and complications and even death. Many studies suggest that long noncoding RNAs (lncRNAs) are involved in the mechanism of vasculitis development in children and can be used to diagnose or predict prognosis by lncRNAs. In existing drug therapies, lncRNAs are also involved in drug-mediated treatment mechanisms and are expected to improve drug toxicity. The aim of this review is to summarize the link between lncRNAs and the pathogenesis of KD and HSP. In addition, we review the potential applications of lncRNAs in multiple dimensions, such as diagnosis, treatment, and prognosis prediction. This review highlights that targeting lncRNAs may be a novel therapeutic strategy to improve and treat KD and HSP.

Relationship between IL-17A gene polymorphism and susceptibility to Kawasaki disease

OBJECTIVES

Kawasaki disease (KD) is the most common autoimmune vasculitis syndrome in children, which supposed be a complex polygenic disorder. Interleukin-17 (IL-17) is a member of the pro-inflammatory cytokine family, which has a strong pro-inflammatory effect and can participate in various acute and chronic inflammatory responses. This study aims to investigate the relationship between the single-nucleotide polymorphism (SNP) locus rs3819025 in the IL-17A gene and the susceptibility to KD.

METHODS

A total of 120 patients with KD who met the diagnostic criteria (the KD group) and 120 healthy children (the control group) were enrolled retrospectively in this study. Polymerase chain reaction (PCR) and DNA direct sequencing were used to detect the SNPs of children in the 2 groups.

RESULTS

The frequencies of GG, GA, and AA genotypes of rs3819025 locus in the IL-17A gene in the KD group were 82.5%, 17.5%, and 0, respectively, and the frequencies of GG, GA, and AA genotypes in the control group were 72.5%, 22.5%, and 5.0%, respectively. There were significant differences in both genotype (χ2=7.524, P=0.023). The allele frequencies G and A of rs3819025 locus in the KD group were 91.25% and 8.75%, respectively, while those in the control group were 83.75% and 16.25%, respectively. There was significant difference between the 2 groups (χ2=6.171, P=0.013). The distribution frequencies of GG or GA genotype and G or A allele were 88.46% or 11.54% and 94.23% or 5.77% in the KD group with coronary artery lesion, respectively. The distribution frequencies of GG or GA genotype and G or A allele were 78.72% or 21.28% and 89.36% or 10.64% in the KD group without coronary artery lesion, respectively. There were no significant differences in genotype and allele frequencies of rs3819025 between the KD with coronary artery lesion group and the KD group without coronary artery lesion (both P>0.05). Besides, children with the allele A had a 2.023 times higher risk of KD than those without the allele A (χ2=6.171, P=0.013; OR=2.023, 95% CI 1.151 to 3.557).

CONCLUSIONS

The locus rs3819025 in the IL-17A gene is associated with the pathogenesis of KD. The allele A of the locus rs3819025 in the IL-17A gene may be a risk factor for KD.

MiR-223-3p affects the proliferation and apoptosis of HCAECs in Kawasaki disease by regulating the expression of FOXP3

OBJECTIVE

Kawasaki disease (KD) can lead to permanent damage to coronary structures, the pathogenesis of which remains unknown. This experiment was designed to investigate whether miR-223-3p secreted in the serum of KD patients affects the proliferation and apoptosis of HCAECs in KD by regulating FOXP3.

METHODS

Blood samples were collected in acute febrile phase of KD, after IVIG treatment, and from healthy controls. Transfected into HCAECs cells by synthetic FOXP3 siRNA/NC. A co-culture system was established between HCAECs cells transfected with FOXP3 siRNA/NC and THP1 cells added with three sera.

RESULTS

Compared with the control group, the expressions of miR-223-3p, RORγt, and Th17 in serum of KD patients were significantly upregulated, and the expressions of TGF-β1, FOXP3 and Treg were significantly downregulated. At the same time, the levels of IL-6, IL-17, and IL-23 were significantly increased, and the levels of IL-10 and FOXP3 were significantly decreased. After IVIG treatment, the patient's above results were reversed. The serum of KD patients increased the expression of miR-223-3p and inhibited the expression of FOXP3 in HCAECs cells. IVIG serum is the opposite. Overexpression of miR-223-3p also promoted the apoptosis of HCAECs. In addition, serum from KD patients promoted apoptosis, whereas serum after IVIG treatment inhibited apoptosis. KD patient serum downregulated the expression of FOXP3, Bcl2, TGF-β1 and IL-10 in cells, and upregulated the expression of caspase3, Bax, IL-17, IL-6, and IL-23. The opposite results were obtained with IVIG-treated sera.

CONCLUSION

miR-223-3p secreted in serum of KD patients can regulate the expression of FOXP3 and affect the proliferation, apoptosis, and inflammation of cells.

Integrative multi-ancestry genetic analysis of gene regulation in coronary arteries prioritizes disease risk loci

Genome-wide association studies (GWAS) have identified hundreds of genetic risk loci for coronary artery disease (CAD). However, non-European populations are underrepresented in GWAS and the causal gene-regulatory mechanisms of these risk loci during atherosclerosis remain unclear. We incorporated local ancestry and haplotype information to identify quantitative trait loci (QTL) for gene expression and splicing in coronary arteries obtained from 138 ancestrally diverse Americans. Of 2,132 eQTL-associated genes (eGenes), 47% were previously unreported in coronary arteries and 19% exhibited cell-type-specific expression. Colocalization analysis with GWAS identified subgroups of eGenes unique to CAD and blood pressure. Fine-mapping highlighted additional eGenes of interest, including TBX20 and IL5 . Splicing (s)QTLs for 1,690 genes were also identified, among which TOR1AIP1 and ULK3 sQTLs demonstrated the importance of evaluating splicing events to accurately identify disease-relevant gene expression. Our work provides the first human coronary artery eQTL resource from a patient sample and exemplifies the necessity of diverse study populations and multi-omic approaches to characterize gene regulation in critical disease processes.

Study Design Overview

Kawasaki disease complicated with shock syndrome, macrophage activation syndrome, and acute abdomen in children: Two case reports

Background

Kawasaki disease (KD) is an acute systemic vasculitis that can involve multiple organs. Few reports have been published about KD patients presenting with multiple complications such as acute abdomen, KD shock syndrome (KDSS), and macrophage activation syndrome (MAS).

Case Description

We present the cases of two males (9 and 12 years old) diagnosed with KD accompanied by rare manifestations. Case 1 is a 9-year-old male treated for acute appendicitis, KDSS, and MAS. Case 2 is a 12-year-old male who presented with KDSS, MAS, and an ileal perforation. They were treated with intravenous immunoglobulin, aspirin, high-dose corticosteroids, vasoactive drugs, and symptomatic treatment, with good outcomes.

Conclusions

Clinicians should be aware of the possibility of KD in the presence of fever and unusual manifestations, such as severe inflammatory indicators and acute abdomen that is nonresponsive to antibiotic therapy. Meanwhile, KD-related unusual complications should be recognized, such as KDSS and MAS.

Ultrasound evaluation of endothelial dysfunction in immunoglobulin-resistant children with acute Kawasaki disease

INTRODUCTION

Given the evidence that brachial artery flow-mediated dilation (FMD) is declined in children later after the onset of Kawasaki disease (KD), we hypothesized that indicators that detect the situation of the endothelium are useful parameters that can accurately reflect subclinical dysfunction in resistant patients and assist in differentiating patients with KD at a higher risk of IVIG resistance, which may be valuable in better understanding how to protect patients from endothelial and thrombotic complications.

METHODS

Fifty IVIG-resistant KD children, 120 IVIG-responsive KD children, 35 febrile children with acute upper respiratory infection, and 50 healthy controls were recruited, and indicators reflecting endothelial inflammation, including flow-mediated dilation (FMD), were measured. Receiver operating characteristic (ROC) curve analysis was utilized to determine the threshold values of these indicators of IVIG resistance. Multiple logistic regression analysis was performed to determine whether FMD was an independent predictor of IVIG-resistant patients.

RESULTS

In comparison with the lab data, PCT, Na + , and FMD exhibited AUCs of 0.727, 0.653, and 0.698 (P < 0.05), respectively, in predicting IVIG resistance in KD through ROC analysis. PCT > 1.69 ng/ml, Na +  < 133.2 mmol/l, and FMD < 5.79% were independent predictors of IVIG resistance in KD (OR 4.257, 3.516, 3.563, 95% CI 1.549 ~ 11.700, 1.277 ~ 9.680, 1.299 ~ 9.772, P < 0.05).

CONCLUSION

More severe endothelial dysfunction, especially lower FMD, was present in IVIG-resistant patients than in IVIG-responsive patients. It is a helpful diagnostic tool that provides supportive criteria to detect KD patients at a higher risk of IVIG resistance when FMD < 5.79% in children. Key Points • IVIG-resistant KD patients have more severe endothelial dysfunction than IVIG-sensitive patients. • FMD < 5.79% may indicate an increased risk of IVIG resistance in children with Kawasaki disease.

Pathogenesis and Preventive Tactics of Immune-Mediated Non-Pulmonary COVID-19 in Children and Beyond

The COVID-19 pandemic has evolved to immune escape and threatened small children and the elderly with a higher severity and fatality of non-pulmonary diseases. These life-threatening non-pulmonary COVID-19 diseases such as acute necrotizing encephalopathies (ANE) and multisystem inflammatory syndrome in children (MIS-C) are more prevalent in children. However, the mortality of multisystem inflammatory syndrome in adults (MIS-A) is much higher than that of MIS-C although the incidence of MIS-A is lower. Clarification of immunopathogenesis and genetic susceptibility of inflammatory non-pulmonary COVID-19 diseases would provide an appropriate guide for the crisis management and prevention of morbidity and fatality in the ongoing pandemic. This review article described three inflammatory non-pulmonary COVID-19 diseases including (1) meningoencephalitis (ME), (2) acute necrotizing encephalopathies (ANE), and (3) post-infectious multisystem inflammatory syndrome in children (MIS-C) and in adults (MIS-A). To prevent these life-threatening non-pulmonary COVID-19 diseases, hosts carrying susceptible genetic variants should receive prophylactic vaccines, avoid febrile respiratory tract infection, and institute immunomodulators and mitochondrial cocktails as early as possible.

Non-coding RNAs in Kawasaki disease: Molecular mechanisms and clinical implications

Kawasaki disease (KD) is an acute self-limiting vasculitis with coronary complications, usually occurring in children. The incidence of KD in children is increasing year by year, mainly in East Asian countries, but relatively stably in Europe and America. Although studies on KD have been reported, the pathogenesis of KD is unknown. With the development of high-throughput sequencing technology, growing number of regulatory noncoding RNAs (ncRNAs) including microRNA (miRNA), long noncoding RNA (lncRNA), and circular RNA (circRNA) have been identified to involved in KD. However, the role of ncRNAs in KD has not been comprehensively elucidated. Therefore, it is significative to study the regulatory role of ncRNA in KD, which might help to uncover new and effective therapeutic strategies for KD. In this review, we summarize recent studies on ncRNA in KD from the perspectives of immune disorders, inflammatory disorders, and endothelial dysfunction, and highlight the potential of ncRNAs as therapeutic targets for KD.

Explanations for 10 of the most puzzling aspects of multisystem inflammatory syndrome and other Kawasaki-like diseases

WHAT IS KNOWN AND OBJECTIVE

An extensively documented multisystem inflammatory syndrome (MIS) has been observed in a small but significant percentage of COVID-19 patients, in some adults but primarily in paediatric patients, and for these patients it is sometimes called MIS-C.

COMMENT

Kawasaki disease has also been observed over the last several decades in patients that tested positive for a variety of very virulent pathogens. Several differences and similarities between MIS-C and Kawasaki disease pathology have been observed. Several puzzling aspects of MIS-C, Kawasaki disease and other Kawasaki-like diseases have been discussed, but not yet explained.

WHAT IS NEW AND CONCLUSION

An explanatory hypothesis has been presented. Using the hypothesis that a transient or permanent inability to quickly phagocytize antigen-antibody immune complexes created by a novel virulent pathogen infection induces a Type III hypersensitivity immune response and the resulting proteinase exposure and expression of new autoantigens are the fundamental steps for MIS and other Kawasaki-like diseases, it is possible to provide straightforward explanations for at least 10 of the most puzzling aspects of these diseases. The validity of the hypothesis itself is also supported by its ability to provide consistent and straightforward explanations for a large number of these disease aspects. Furthermore, these straightforward explanations and the explanatory hypothesis on which they are based also suggest several potential new treatments, which could possibly be more effective than various treatments in current use.

Multisystem inflammatory syndrome in children and Kawasaki disease: a critical comparison

Children and adolescents infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are predominantly asymptomatic or have mild symptoms compared with the more severe coronavirus disease 2019 (COVID-19) described in adults. However, SARS-CoV-2 is also associated with a widely reported but poorly understood paediatric systemic vasculitis. This multisystem inflammatory syndrome in children (MIS-C) has features that overlap with myocarditis, toxic-shock syndrome and Kawasaki disease. Current evidence indicates that MIS-C is the result of an exaggerated innate and adaptive immune response, characterized by a cytokine storm, and that it is triggered by prior SARS-CoV-2 exposure. Epidemiological, clinical and immunological differences classify MIS-C as being distinct from Kawasaki disease. Differences include the age range, and the geographical and ethnic distribution of patients. MIS-C is associated with prominent gastrointestinal and cardiovascular system involvement, admission to intensive care unit, neutrophilia, lymphopenia, high levels of IFNγ and low counts of naive CD4⁺ T cells, with a high proportion of activated memory T cells. Further investigation of MIS-C will continue to enhance our understanding of similar conditions associated with a cytokine storm.