High levels of IgA-containing circulating immune complex and secretory IgA in Kawasaki disease

Gut Microbiota Alterations in Patients With Kawasaki Disease

The intestinal microbiota influences many host biological processes, including metabolism, intestinal barrier functions, and immune responses in the gut and distant organs. Alterations in its composition have been associated with the development of inflammatory disorders and cardiovascular diseases, including Kawasaki disease (KD). KD is an acute pediatric vasculitis of unknown etiology and the leading cause of acquired heart disease in children in the United States. The presence of gastrointestinal symptoms in the acute phase of KD has been associated with an increased risk of treatment resistance and the development of coronary artery aneurysms. Studies report alterations in fecal bacterial communities of patients with KD, characterized by the blooming of pathogenic bacteria and decreased relative abundance of short-chain fatty acid-producing bacteria. However, causality and functionality cannot be established from these observational patient cohorts of KD. This highlights the need for more advanced and rigorous studies to establish causality and functionality in both experimental models of KD vasculitis and patient cohorts. Here, we review the evidence linking an altered gut microbiota composition to the development of KD, assess the potential mechanisms involved in this process, and discuss the potential therapeutic value of these observations.

Immune and non-immune mechanisms that determine vasculitis and coronary artery aneurysm topography in Kawasaki disease and MIS-C

The overlap between multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease (KD) including coronary artery aneurysms (CAA) and broadly shared gastrointestinal and mucocutaneous disease is poorly defined. In this perspective, we highlight common age-related extravascular epicardial microanatomical and immunological factors that might culminate in CAA expression in both MIS-C and KD. Specifically, the coronary vasa vasorum originates outside the major coronary arteries. Widespread inflammation in the epicardial interstitial compartment in shared between KD and MIS-C. Age-related changes in the neonatal and immature coronary vasculature including the impact of coronary artery biomechanical factors including coronary vessel calibre, age-related vessel distensibility, flow, and vessel neurovascular innervation may explain the decreasing CAA frequency from neonates to older children and the virtual absence of CAA in young adults with the MIS-C phenotype. Other KD and MIS-C features including mucocutaneous disease with keratinocyte-related immunopathology corroborate that disease phenotypes are centrally influenced by inflammation originating outside vessel walls but a potential role for primary coronary artery vascular wall inflammation cannot be excluded. Hence, common extravascular originating tissue-specific responses to aetiologically diverse triggers including superantigens may lead to widespread interstitial tissue inflammation characteristically manifesting as CAA development, especially in younger subjects. Given that CAA is virtually absent in adults, further studies are needed to ascertain whether epicardial interstitial inflammation may impact on both coronary artery physiology and cardiac conduction tissue and contribute to cardiovascular disease- a hitherto unappreciated consideration.

Increased Risk of Asthma and Allergic Rhinitis in Patients With a Past History of Kawasaki Disease: A Systematic Review and Meta-Analyses

Background: Allergic diseases are frequently observed in children with Kawasaki disease (KD). However, the evidence supporting the association between KD and allergies has been conflicting. The objective of the current study is to examine the association between KD and allergic diseases. Methods: We conducted an electronic search using PubMed, Embase, and the Cochrane through 24 July 2021. The inclusion criteria consisted of studies that examined the prevalence of allergic diseases in children with a previous diagnosis of KD and in a comparison group. We pooled studies by using a random effects model. The effects of KD on the subsequent risk of allergic diseases were expressed as odds ratio (OR) with 95% confidence intervals (CI). Results: We included a total of four studies that assessed the effect of KD on asthma, allergic rhinitis, and atopic dermatitis vs. non-KD children (KD individuals for asthma, four studies, n = 8,474; allergic rhinitis, four studies, n = 8,474; atopic dermatitis, three studies, n = 8,330). The overall prevalence of asthma, allergic rhinitis, and atopic dermatitis was 9.12, 27.63, and 6.55% among patients with previous KD. The meta-analysis showed a significantly increased risk of asthma (OR:1.437, CI: 1.067-1.937) and allergic rhinitis (OR: 1.726, CI: 1.291-2.307) in patients with KD, compared with the control groups. However, patients with KD did not have a significantly different level of risk of atopic dermatitis (OR: 1.243, 95% CI: 0.857-1.802). Conclusion: This meta-analysis supports that individuals with KD are more likely to have asthma and allergic rhinitis compared to controls.

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.

A meta-analysis on association between viral infections and Kawasaki disease in children

Aim: To investigate the association between different viral infections and the development of Kawasaki disease (KD) in children. Materials & methods: Electronic databases were searched for relevant studies published from inception to May 2020. The pooled odds ratios (ORs) of the association of different viral pathogens with KD were estimated using a random-effects model weighted by the inverse variance method. Results: The strongest associations were found between KD and human parvovirus B19 viremia (OR = 41.05; 95% CI: 5.13–328.28; I-square = 0%), EBV IgM seropositivity (OR = 7.18; 95% CI: 3.65–14.12, I-square = 0%) and human herpesvirus-6 IgG seropositivity (OR = 5.83; 95% CI: 1.06–32.01). Conclusion: Human parvovirus B19, EBV and human herpesvirus-6 are highly suspected to be key contributors to the development 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.

Kawasaki disease: pathophysiology and insights from mouse models

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

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

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

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

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

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

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

Intestinal Permeability and IgA Provoke Immune Vasculitis Linked to Cardiovascular Inflammation

Recent experimental data and clinical, genetic, and transcriptome evidence from patients converge to suggest a key role of interleukin-1β (IL-1β) in the pathogenesis of Kawasaki disease (KD). However, the molecular mechanisms involved in the development of cardiovascular lesions during KD vasculitis are still unknown. Here, we investigated intestinal barrier function in KD vasculitis and observed evidence of intestinal permeability and elevated circulating secretory immunoglobulin A (sIgA) in KD patients, as well as elevated sIgA and IgA deposition in vascular tissues in a mouse model of KD vasculitis. Targeting intestinal permeability corrected gut permeability, prevented IgA deposition and ameliorated cardiovascular pathology in the mouse model. Using genetic and pharmacologic inhibition of IL-1β signaling, we demonstrate that IL-1β lies upstream of disrupted intestinal barrier function, subsequent IgA vasculitis development, and cardiac inflammation. Targeting mucosal barrier dysfunction and the IL-1β pathway may also be applicable to other IgA-related diseases, including IgA vasculitis and IgA nephropathy.

Kawasaki Disease: The Role of Immune Complexes Revisited

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

B Cells and Antibodies in Kawasaki Disease

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

Gastrointestinal presentation of Kawasaki disease: A red flag for severe disease?

Background

Kawasaki disease (KD) is a febrile systemic vasculitis of unknown etiology and the main cause of acquired heart disease among children in the developed world. To date, abdominal involvement at presentation is not recognized as a risk factor for a more severe form of the disease.

Objective

To evaluate whether presenting abdominal manifestations identify a group at major risk for Intravenous immunoglobulin (IVIG)-resistance and coronary lesions.

Methods

Retrospective study of KD patients diagnosed between 2000 and 2015 in 13 pediatric units in Italy. Patients were divided into 2 groups according to the presence or absence of abdominal manifestations at onset. We compared their demographic and clinical data, IVIG-responsiveness, coronary ectasia/aneurysms, laboratory findings from the acute and subacute phases.

Results

302 patients (181 boys) were enrolled: 106 patients with, and 196 patients without presenting abdominal features. Seasonality was different between the groups (p = 0.034). Patients with abdominal manifestations were younger (p = 0.006) and more frequently underwent delayed treatment (p = 0.014). In the acute phase, patients with abdominal presentation had higher platelet counts (PLT) (p = 0.042) and lower albuminemia (p = 0.009), while, in the subacute phase, they had higher white blood cell counts (WBC) and PLT (p = 0.002 and p < 0.005, respectively) and lower red blood cell counts (RBC) and hemoglobin (Hb) (p = 0.031 and p 0.009). Moreover, the above mentioned group was more likely to be IVIG-resistant (p < 0.005) and have coronary aneurysms (p = 0.007). In the multivariate analysis, presenting abdominal manifestations, age younger than 6 months, IVIG- resistance, delayed treatment and albumin concentration in the acute phase were independent risk factors for coronary aneurysms (respectively p<0.005, <0.005, = 0.005 and 0.009).

Conclusions

This is the first multicenter report demonstrating that presenting gastrointestinal features in KD identify patients at higher risk for IVIG-resistance and for the development of coronary aneurysms in a predominantly Caucasian population.

Clinical trial registration

8/20014/O/OssN.

Suppressed plasmablast responses in febrile infants, including children with Kawasaki disease

Background

Kawasaki disease (KD), the leading cause of acquired heart disease in children, primarily affects infants and toddlers. Investigations on immune responses during KD are hampered by a limited understanding of normal immune responses in these ages. It’s well known that Infants have poorer vaccine responses and difficulty with maintaining prolonged serum immunity, but there are few studies on human infants detailing immune deficiencies. Limited studies propose an inability to maintain life-long bone marrow plasma cells. Plasmablasts are a transitional cell form of B cells that lead to long-term Plasma cells. Plasmablasts levels rise in the peripheral blood after exposure to a foreign antigen. In adult studies, these responses are both temporally and functionally well characterized. To date, there have been few studies on plasmablasts in the predominant age range of KD.

Methods

Children presenting to an urban pediatric emergency room undergoing laboratory evaluation, who had concern of KD or had fever and symptoms overlapping those of KD, were recruited. Peripheral blood mononuclear cells were isolated and evaluated utilizing flow cytometry with specific B cell markers from 18 KD subjects and 69 febrile controls.

Results

Plasmablast numbers and temporal formation are similar between infectious disease controls and KD subjects. In both groups, infants have diminished plasmablast responses compared to older children.

Conclusion

In this single-time point survey, infants have a blunted peripheral plasmablast response. Overall, similar plasmablast responses in KD and controls support an infectious disease relationship to KD. Future time-course studies of plasmablasts in infants are warranted as this phenomenon may contribute to observed immune responses in this age group.

Histopathological evaluation of horse serum-induced immune complex vasculitis in swine: implication to coronary artery lesions in Kawasaki disease

BACKGROUND

Immune complex (IC) vasculitis can be experimentally induced in animal models by intravenous injection of horse serum (HS), and the findings of HS-induced IC vasculitis in swine were very similar to that of Kawasaki disease (KD). The IC mechanism may be involved in the pathogenesis of vasculitis in KD. Here, we studied the two-dimensional (2D) echocardiographic and histopathological findings of acute, subacute, and healing phases of vasculitis induced by two different types of HS, and the reproducibility of IC vasculitis in swine.

METHODS AND RESULTS

Our study group consisted of 24 pure-bred landrace male piglets of 1.5-3 months of age. They were divided into three HS groups (n = 17), namely, Group A (n = 8) receiving gamma globulin-free HS, and Group B (n = 6) receiving donor herd HS, three doses at 5-day intervals, and Group C (n = 3) that received only one dose of donor herd HS on Day 1, and the saline group (n = 7) that received three doses of intravenous normal saline (NS) at 5-day intervals. The 2D echocardiography was performed every 3-4 days, and all piglets were killed for histopathological studies at different dates from Days 2 to Day 60. All the HS groups developed rashes and demonstrated significant dilation (54-150%) of coronary arteries in Groups A and B; when compared (p < 0.02) with 9-53% dilation in Group C and the saline group. Histopathological changes of test groups were asymmetric coronary vasculitis in various stages, whereas none of the piglets in the control group developed vasculitis. No significant difference in the echocardiographic and histopathological findings was observed among the piglets that received two types of HS.

CONCLUSION

HS can induce IC vasculitis in swine. The rashes and 2D echocardiographic and histopathological studies of the acute to healing phases showed close similarities with KD, and it is concluded that swine may serve as a unique experimental model for IC vasculitis and for various therapeutic trials.

Study of the autoantibody profile after the acute phase of Kawasaki disease in a cohort of children from North India

A study of organ-specific and organ-nonspecific autoantibodies was carried out in 21 children being followed up after a diagnosis of Kawasaki disease at a tertiary care center of North India. Anti-nuclear antibodies were detected in 9.5% patients while anti-thyroid microsomal antibodies were detected in 23.9% patients. Other autoantibodies (e.g. anti-parietal cell antibody, anti-liver kidney microsomal antibody anti-neutrophil cytoplasmic antibody, anti-mitochondrial antibody and anti-smooth muscle antibody) were not detected in any of our patients. Children with Kawasaki disease need to be monitored for the development of autoantibodies during follow-up.

Increased production of serum IgA-class antibody to lipid A in Kawasaki disease

BACKGROUND

The etiology of Kawasaki disease (KD) remains unknown. To investigate whether a conventional bacterial antigen is involved in the pathogenesis of KD, we studied the serum response to lipopolysaccharide (LPS).

METHODS

We measured the serum levels of IgG-, IgM- and IgA-class antibodies (Ab) to lipid A, a toxic site of LPS, using enzyme-linked immunosorbent assay in 20 patients with KD, 11 patients with Gram-negative bacterial infection (GNBI), 27 healthy children and 12 healthy adults.

RESULTS

The serum levels of anti-lipid A IgG, IgM and IgA tended to increase with advancing age in healthy children older than 6 months of age. The mean level of anti-lipid A IgM in the acute phase of GNBI and the mean levels of anti-lipid A IgM and IgA in the acute phase of KD were found to increase significantly, in comparison to the age-matched controls. Furthermore, the mean level of anti-lipid A IgA also showed a significant increase from the acute to the subacute phases of KD. Regarding the IgA-subclass response, higher titers of anti-lipid A specific Ab were seen in the IgA2 subclass than in the IgA1 subclass.

CONCLUSION

These findings indicate that KD patients demonstrate an intense response to lipid A in the IgA, especially IgA2-subclass, thus suggesting that an unusual activation of the mucosal immune response to a ubiquitous antigen derived from Gram-negative bacteria may be involved in the pathogenesis of KD.

Surface and cytoplasmic immunoglobulin expression in circulating B-lymphocytes in acute Kawasaki disease

Kawasaki disease (KD) is an acute vasculitis of young childhood predominantly affecting the coronary arteries. IgA plasma cells have been found to infiltrate vascular and nonvascular tissues in fatal acute KD. To determine whether IgA B-lymphocytes were increased in the peripheral blood of patients with KD, we performed three-color flow cytometry to detect surface and cytoplasmic immunoglobulin expression (IgA, IgM, IgD, and IgG) of peripheral B-lymphocytes in KD patients during the acute, subacute, and convalescent stages of illness and in age-matched febrile and afebrile pediatric controls. Surprisingly, absolute numbers of B-lymphocytes expressing IgA were found to be significantly lower in peripheral blood of acute KD patients compared with febrile and afebrile pediatric controls. These findings indicate that IgA plasma cells are not present in KD tissue as a result of excess numbers of these IgA B-lymphocytes in peripheral blood. We speculate that IgA B-lymphocytes are selectively withdrawn from the peripheral circulation into KD target tissues as part of a specific IgA immune response.

Kawasaki syndrome

Kawasaki syndrome is a fascinating worldwide illness of young children. This acute self-limited vasculitis has become the most common cause of acquired heart disease in children in the United States and Japan. KS causes significant coronary artery disease that may lead to myocardial infarction and sudden death. Clinical and epidemiologic features of KS support an infectious cause, but the etiology remains unknown. Clearly, additional research on the cause of KS and its pathogenesis is needed urgently to allow for improved diagnosis; more specific therapy; and, ultimately, prevention of the disorder.

Kawasaki syndrome

Kawasaki syndrome (KS) is an acute, sometimes fatal vasculitis of young children. KS has replaced acute rheumatic fever as the most common cause of acquired heart disease in children in the United States. The illness is manifested by prolonged fever, conjunctival injection, enanthem, exanthem, erythema and swelling of the hands and feet, and cervical adenopathy. These acute features of illness are self-limiting, but coronary artery abnormalities occur in 20% of untreated patients. The etiology of the illness is unknown, but its clinical and epidemiologic features are most consistent with an infectious cause. Common cardiovascular manifestations of the illness include myocarditis, pericardial effusion, and coronary artery aneurysm formation. Treatment with intravenous gamma globulin (IVGG) and aspirin within the first 10 days of illness reduces the prevalence of coronary artery abnormalities from 20% in those treated with aspirin alone to 4%. Patients who develop coronary artery aneurysms, particularly those who develop giant coronary artery aneurysms, may suffer myocardial infarction secondary to thrombosis or stenosis in the abnormal vessel. Additional research to determine the cause of KS is urgently needed to allow for improved diagnosis, more specific therapy, and prevention of the disorder.

Classical pathway complement activation in Kawasaki syndrome

In this study the complement breakdown products C3d, C4d, Bb and membrane attack complex were measured in plasma of patients with Kawasaki syndrome. The results suggested strong activation of the classical activation pathway. However, there was no significant decrease in hemolytic titer or in the concentrations of the intact proteins C3, C4, and B. The relationship between the serum concentrations of cytokines and complement components was examined; increased interleukin-6 concentration on the fifth day after the onset of fever was found to correlate well with the C3 and B concentrations in serum obtained 5 days later. We conclude that complement activation occurred in Kawasaki syndrome via the classical pathway but that the inflammatory reaction was accompanied by increased production of complement components. As a result, there was increased formation of activation products without changes in the serum complement levels.