Evidence for a superantigen mediated process in Kawasaki disease

Retrospective evaluation of 130 cases with kawasaki disease follow-up in a tertiary care center in Turkey between 1999 and 2019: a 20-year experience

OBJECTIVES

Kawasaki disease (KD), which is a medium vessel vasculitis, is common in Asian countries and is the most common cause of childhood-acquired heart diseases in developed countries. However, disease course and epidemiological data are limited in non-Asian developing countries like ours. We aimed to evaluate the clinical features and prognosis of patients with KD in our country and ethnicity, one of the referee centers of our country.

METHODS

Patients with KD in our center for the last 20 years in the pre-COVID-19 pandemic era were included in the study. The clinical and laboratory findings, treatments, and follow-up findings were reviewed retrospectively in different age groups.

RESULTS

Of the 130 patients, 82 (63%) were male. The median age at diagnosis was 2.97 years (2 months-11.5 years). Thirty-six (27.7%) patients were diagnosed with incomplete KD, and there was no significant laboratory difference between incomplete KD and complete KD patients. Thirty-three (25.3%) patients had coronary artery lesions (CAL), and it persisted in only 3 of 33 patients. One of 15 patients with IVIG resistance had CAL. The independent risk factors were days of illness at initial IVIG administration for CAL (p = 0.013, OR [95%CI] = 1.20 [1.04-1.38]) and low hemoglobin (p = 0.003, OR [95%CI] = 0.51 [0.33-0.79]) and low sodium for IVIG resistance (p = 0.012, OR [95%CI] = 0.81[0.69-0.95]).

CONCLUSIONS

The rate of CAL is approximately three times higher in our results than in the Japanese data in recent years. We showed that the time of IVIG administration is the most critical factor for preventing CAL. Wide-ranging studies are needed to decently predict the disease process according to the age and region of patients.

Kawasaki Disease-Associated Cytokine Storm Syndrome

Kawasaki disease (KD) is a hyperinflammatory syndrome manifesting as an acute systemic vasculitis characterized by fever, nonsuppurative conjunctival injection, rash, oral mucositis, extremity changes, and cervical lymphadenopathy. KD predominantly affects young children and shares clinical features and immunobiology with other hyperinflammation syndromes including systemic juvenile idiopathic arthritis (sJIA) and multisystem inflammatory syndrome in children (MIS-C). Cytokine storm syndrome (CSS) is an acute complication in ~2% of KD patients; however, the incidence is likely underestimated as many clinical and laboratory features of both diseases overlap. CSS should be entertained when a child with KD is unresponsive to IVIG therapy with recalcitrant fever. Early recognition and prompt institution of immunomodulatory treatment can substantially reduce the mortality and morbidity of CSS in KD. Given the known pathogenetic role of IL-1β in both syndromes, the early use of IL-1 blockers in refractory KD with CSS deserves consideration.

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.

Single-cell RNA sequencing of peripheral blood mononuclear cells from acute Kawasaki disease patients

Kawasaki disease (KD) is the most common cause of acquired heart disease in children in developed countries. Although functional and phenotypic changes of immune cells have been reported, a global understanding of immune responses underlying acute KD is unclear. Here, using single-cell RNA sequencing, we profile peripheral blood mononuclear cells from seven patients with acute KD before and after intravenous immunoglobulin therapy and from three age-matched healthy controls. The most differentially expressed genes are identified in monocytes, with high expression of pro-inflammatory mediators, immunoglobulin receptors and low expression of MHC class II genes in acute KD. Single-cell RNA sequencing and flow cytometry analyses, of cells from an additional 16 KD patients, show that although the percentage of total B cells is substantially decreased after therapy, the percentage of plasma cells among the B cells is significantly increased. The percentage of CD8+ T cells is decreased in acute KD, notably effector memory CD8+ T cells compared with healthy controls. Oligoclonal expansions of both B cell receptors and T cell receptors are observed after therapy. We identify biological processes potentially underlying the changes of each cell type. The single-cell landscape of both innate and adaptive immune responses provides insights into pathogenesis and therapy of KD.

Non-Typhoidal Salmonella and the Risk of Kawasaki Disease: A Nationwide Population-Based Cohort Study

Objective

The aim of this study was to investigate the relationship between non-typhoidal Salmonella (NTS) infection and the risk of Kawasaki disease (KD) by using a nationwide population-based data set in Taiwan.

Methods

In this retrospective cohort study, we enrolled 69,116 patients under 18 years of age, with NTS from January 1^st, 2000, to December 31^st, 2013, using the population-based National Health Insurance Research Database of Taiwan. A comparison group without NTS was matched (at a 1:4 ratio) by propensity score. The two cohorts were followed from the initial diagnosis of NTS until the date of KD development or December 31^st, 2013. Cox proportional hazard regression analysis was conducted to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) after adjusting for covariates. Also, we conducted sensitivity analyses to examine our findings.

Results

After adjusting for covariates, the risk of KD for the children with NTS was significantly higher than that of the comparison group (hazard ratio = 1.31; 95% confidence interval = 1.03-1.66; p < 0.01). Stratified analysis showed that the associated risk of the investigated outcome was significant in children aged ≤2 years (aHR= 1.31, 95% C.I. 1.02-1.69), in female patients (aHR= 1.46, 95% C.I. 1.03-2.08), and in those without allergic diseases.

Conclusions

NTS is associated with an increased risk of KD in Taiwanese children.

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.

Identification of a unique TCR repertoire, consistent with a superantigen selection process in Children with Multi-system Inflammatory Syndrome

Multisystem Inflammatory Syndrome in Children (MIS-C), a hyperinflammatory syndrome associated with SARS-CoV-2 infection, shares many clinical features with toxic shock syndrome, which is triggered by bacterial superantigens. The superantigen specificity for binding different Vβ-chains results in Vβ-skewing, whereby T cells with specific Vβ-chains and diverse antigen specificity are overrepresented in the TCR repertoire. Here, we characterized the TCR repertoire of MIS-C patients and found a profound expansion of TCR Βeta Variable gene (TRBV)11-2. Furthermore, TRBV11-2 skewing was remarkably correlated with MIS-C severity and serum cytokine levels. Further analysis of TRBJ gene usage and CDR3 length distribution of MIS-C expanding TRBV11-2 clones revealed extensive junctional diversity, indicating a superantigen-mediated selection process for TRBV expansion. In silico modelling indicates that polyacidic residues in TCR Vβ11-2 engage in strong interactions with the superantigen-like motif of SARS-CoV-2 spike glycoprotein. Overall, our data indicate that the immune response in MIS-C is consistent with superantigenic activation.

Kawasaki syndrome: role of superantigens revisited

Kawasaki syndrome (KS) is an acute vasculitis in children complicated by the development of heart disease. Despite its description over 50 years ago, the etiology of coronary artery disease in KS is unknown. High dose intravenous immunoglobulin is the most effective approach to reduce cardiovascular complications. It remains unclear why patients with KS develop coronary artery aneurysms. A subset of patients is resistant to immunoglobulin therapy. Given the heterogeneity of clinical features, variability of history, and therapeutic response, KS may be a cluster of phenotypes triggered by multiple infectious agents and influenced by various environmental, genetic, and immunologic responses. The cause of KS is unknown, and a diagnostic test remains lacking. A better understanding of mechanisms leading to acute KS would contribute to a more precision medicine approach for this complex disease. In the current viewpoint, we make the case for microbial superantigens as important causes of KS.

Familial Kawasaki disease and acute glomerulonephritis: case report and review of literature

We report two siblings, a 6-year-old boy and his 4-year-old sister who were admitted with fever for 15 days and features of Kawasaki disease. After admission to the hospital, both patients developed red urine and headache. Blood pressure was found to be high in relation to blood pressure percentiles for both patients. Urine analysis showed the features of acute glomerulonephritis with normal urine output and renal function. A multidisciplinary discussion with the paediatric nephrologist, rheumatologist and cardiologist was conducted, and intravenous immunoglobulins, aspirin, pulsed methylprednisolone and antihypertensive therapy were added to the treatment plan with a good outcome.

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).

Update on association between Kawasaki disease and infection

The relationship between infection and Kawasaki disease (KD) remains unclear. Infection has long been considered a key predisposing factor for KD. Bacterial and viral agents may be related to the onset of KD because of superantigen and cytokine production. Various bacterial and viral infections have been reported to be associated with KD, but the actual mechanism remains unknown. The higher association between KD and enterovirus has been well documented by using Taiwan National Health Insurance Research Database. However, no evidence has been obtained that various bacterial and viral infections induce KD. Comprehensive research, including infectious agents, should be conducted to elucidate the pathogenesis of KD.

Implications of hepatic dysfunction in Kawasaki disease: Time-related changes in aspartate aminotransferase, alanine aminotransferase, total bilirubin, and C-reactive protein levels

IMPORTANCE

The cause of the hepatic dysfunction that commonly accompanies Kawasaki disease (KD) remains unclear.

OBJECTIVE

We tried to clarify the cause of the hepatic dysfunction.

METHODS

A total of 381 consecutive patients with acute KD, who had undergone inpatient treatment with intravenous immunoglobulin until the 7th day of illness, were divided into a group of 199 patients with an alanine aminotransferase (ALT) level ≥ 40 IU/L on admission (group I), a group of 52 patients with an ALT level ≥ 40 IU/L at some point after admission (group II), and a group of 130 patients with ALT levels consistently < 40 IU/L throughout hospitalization (group III). Aspartate aminotransferase (AST), ALT, total bilirubin (T-Bil), and C-reactive protein (CRP) levels were analyzed over time, and time-courses were compared.

RESULTS

In the initial stage of illness, in group I, AST, ALT, T-Bil peaked on days 1-3, and AST tended to improve significantly on the 4th day (P < 0.001). T-Bil improved on day 5 (P < 0.01), and ALT improved significantly on day 6 (P < 0.001). CRP increased every day up to day 6 (P < 0.001). In group II, AST and ALT increased after admission, and thereafter CRP increased, then decreased. The frequency of use of aspirin and aspirin doses did not differ significantly in the three groups.

INTERPRETATION

Recovery from liver dysfunction occurred in the initial stage of illness in group I-within the period of CRP exacerbation, which is an indicator of systemic inflammation.

Kawasaki disease: a matter of innate immunity

Kawasaki disease (KD) is an acute systemic vasculitis of childhood that does not have a known cause or aetiology. The epidemiological features (existence of epidemics, community outbreaks and seasonality), unique age distribution and clinical symptoms and signs of KD suggest that the disease is caused by one or more infectious environmental triggers. However, KD is not transmitted person-to-person and does not occur in clusters within households, schools or nurseries. KD is a self-limited illness that is not associated with the production of autoantibodies or the deposition of immune complexes, and it rarely recurs. Regarding the underlying pathophysiology of KD, innate immune activity (the inflammasome) is believed to play a role in the development of KD vasculitis, based on the results of studies with animal models and the clinical and laboratory findings of KD patients. Animal studies have demonstrated that innate immune pathogen-associated molecular patterns (PAMPs) can cause vasculitis independently of acquired immunity and have provided valuable insights regarding the underlying mechanisms of this phenomenon. To validate this concept, we recently searched for KD-specific PAMPs and identified such molecules with high specificity and sensitivity. These molecules have structures similar to those of microbe-associated molecular patterns (MAMPs), as shown by liquid chromatography-tandem mass spectrometry. We propose herein that KD is an innate immune disorder resulting from the exposure of a genetically predisposed individual to microbe-derived innate immune stimulants and that it is not a typical infectious disease.

Streptococcal toxins: role in pathogenesis and disease

Group A Streptococcus (Streptococcus pyogenes), group B Streptococcus (Streptococcus agalactiae) and Streptococcus pneumoniae (pneumococcus) are host-adapted bacterial pathogens among the leading infectious causes of human morbidity and mortality. These microbes and related members of the genus Streptococcus produce an array of toxins that act against human cells or tissues, resulting in impaired immune responses and subversion of host physiological processes to benefit the invading microorganism. This toxin repertoire includes haemolysins, proteases, superantigens and other agents that ultimately enhance colonization and survival within the host and promote dissemination of the pathogen.

Persistent endothelial damage after intravenous immunoglobulin therapy in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is an acute systemic vasculitis of unknown etiology. Although endothelial cell damage associated with vasculitis might lead to the hypercoagulability that is involved in coronary artery disease, the changes in coagulation after intravenous immunoglobulin therapy (IVIG) have not been well investigated in KD. The aims of this study were to address the changes in coagulation before and after IVIG in KD, and to further elucidate the coagulation-inflammation axis, with special attention to endothelial damage.

METHODS

We retrospectively collected the laboratory data before and after IVIG in 26 pediatric KD patients treated at the Nara Prefecture Western Medical Center between May 2010 and April 2012. Prothrombin time (PT), activated partial thromboplastin time (APTT) and levels of fibrin/fibrinogen degradation products (FDP) and D-dimer were assessed as coagulation markers. Fibrinogen, ferritin, serum amyloid A, procalcitonin and urine β2 microglobulin were assessed as inflammation markers. Thrombomodulin, antithrombin, factor VIII activity (FVIII:C), and von Willebrand factor antigen (VWF:Ag) were used to assess endothelial damage.

RESULTS

Prolonged PT and APTT before IVIG were significantly shortened after IVIG, and elevated levels of FDP and D-dimer were significantly decreased. Elevated levels of inflammation markers had decreased significantly after IVIG, but levels of FVIII:C and VWF:Ag remained high, even after IVIG.

CONCLUSIONS

Ameliorated inflammation by IVIG might improve the hypercoagulable state. Nevertheless, our results suggest that endothelial damage might be prolonged in IVIG-treated patients. Control of endothelial damage in KD is critical.

Streptococcal superantigens: categorization and clinical associations

Superantigens are key virulence factors in the immunopathogenesis of invasive disease caused by group A streptococcus. These protein exotoxins have also been associated with severe group C and group G streptococcal infections. A number of novel streptococcal superantigens have recently been described with some resulting confusion in their classification. In addition to clarifying the nomenclature of streptococcal superantigens and proposing guidelines for their categorization, this review summarizes the evidence supporting their involvement in various clinical diseases including acute rheumatic fever.

Update on Kawasaki disease: epidemiology, aetiology and pathogenesis

Kawasaki disease is an acute systemic vasculitis predominantly affecting young children. It is due to an abnormal host response to as yet unidentified infectious trigger(s). Kawasaki disease may cause coronary artery damage, long-term cardiovascular morbidity and occasionally mortality, especially if the diagnosis is missed or timely treatment is not given. This is the first of two updates on Kawasaki disease. Here we review recent advances in epidemiology, possible aetiologies, host susceptibility and pathogenesis of this fascinating condition.

Superantigen involvement and susceptibility factors in Kawasaki disease: profiles of TCR Vβ2+ T cells and HLA-DRB1, TNF-α and ITPKC genes among Filipino patients

Superantigens and genetic factors may play roles in the etiology and susceptibility to Kawasaki disease (KD). To investigate these roles, percentages of TCR-Vβ2+ T cells were compared by flow cytometry using anti-Vβ2 monoclonal antibodies and genotyping was done on HLA-DRB1 exon 2, the -308 site of the TNF-α promoter region, and ITPKC SNP rs28493229 by polymerase chain reaction followed by direct sequencing. There were higher percentages of Vβ2+ T-cells in KD patients (9.5 ± 2.15%) compared to healthy controls (7.25 ± 1.48%) (P<0.05, Student's t-test, n=6-8/group). However, no polymorphisms were observed in exon 2 of HLA-DRB1 and in the -308 region of the TNF-α promoter. The ITPKC SNP rs28493229 G/C polymorphism was observed in 1 KD patient and 4 healthy controls. This study suggests that KD etiology may be associated with a superantigen and that HLA-DRB1 exon2, TNF-α -308 region and ITPKC SNP rs28493229 may not be associated with KD. This is the first study investigating Vβ2+ T cells and candidate genes involvement among Filipino KD patients.

Kawasaki disease: basic and pathological findings

Kawasaki disease (KD) is considered to be a kind of systemic vasculitis syndrome. It most frequently affects infants and young children and primarily invades medium-sized muscular arteries, including the coronary arteries. The etiology of KD is unknown, but epidemiological data suggest involvement of infectious agents, such as bacteria and viruses, in the onset of KD. In addition, host genetics underlie the disease's pathogenesis. Histologically, coronary arteritis begins 6-8 days after KD onset, and inflammation of all layers of the artery rapidly ensues. The inflammation spreads completely around the artery, resulting in severe damage to structural components. Then, the artery begins to dilate. KD arteritis is characterized by inflammation consisting of marked accumulation of monocytes/macrophages. Aberrant activation of monocytes/macrophages is thought to be involved in the formation of vascular lesions. Inflammatory-cell infiltration persists until about the 25th day of the disease, after which the inflammatory cells gradually decrease in number. Lesions in all arteries are relatively synchronous, as they evolve from acute to chronic injury. If a giant aneurysm remains or vessel recanalization occurs after thrombotic occlusion of an aneurysm, remodeling of the vascular structure, sometimes including even reocclusion, continues even in the remote stage.

Pathogénie de la maladie de Kawasaki : quoi de neuf ?

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

Kawasaki disease: novel insights into etiology and genetic susceptibility

Kawasaki disease (KD) is a vasculitis of young childhood that particularly affects the coronary arteries. Molecular analysis of the oligoclonal IgA response in acute KD led to production of synthetic KD antibodies. These antibodies identify intracytoplasmic inclusion bodies in acute KD tissues. Light and electron microscopic studies indicate that the inclusion bodies are consistent with aggregates of viral proteins and RNA. Advances in molecular genetic analysis and completion of the Human Genome Project have sparked a worldwide effort to identify genes associated with KD. A polymorphism of one such gene, ITPKC, a negative regulator of T cell activation, confers susceptibility to KD in Japanese populations and increases the risk of developing coronary artery abnormalities in both Japanese and U.S. children. Identification of the etiologic agent and of genes conferring KD susceptibility are the best means of improving diagnosis and therapy and enabling prevention of this important disorder of childhood.

New insights into the prevention of staphylococcal infections and toxic shock syndrome

Staphylococcus aureus is a major human pathogen capable of causing various diseases, from skin infections to life-threatening pneumonia and toxic shock syndrome. S. aureus exoproteins, including superantigens, contribute significantly to the pathogenesis of this organism. Antibiotics inhibit growth, but often provide no protection from S. aureus exoproteins. With the emergence of antibiotic-resistant S. aureus, new therapeutic options to treat or prevent S. aureus-associated diseases are critical. Most S. aureus infections begin on the skin or mucosal surfaces from direct inflammatory or cytotoxic effects of exotoxins. Therefore, antitoxin therapies that prevent toxin production and prevent their effects on host cells are being researched. Current treatments for staphylococcal diseases and recent developments in antitoxin therapeutic agents and vaccines are reviewed.

A case of Kawasaki disease with coexistence of a parapharyngeal abscess requiring incision and drainage

Kawasaki disease (KD) causes multisystemic vasculitis but infrequently manifests with deep neck infections, such as a peritonsillar abscess, peritonsillar or deep neck cellulitis, suppurative parapharyngeal infection, or retropharyngeal abscess. As its etiology is still unknown, the diagnosis is usually made based on typical symptoms. The differential diagnosis between KD and deep neck infections is important, considering the variable head and neck manifestations of KD. There are several reports on KD patients who were initially diagnosed with retropharyngeal abscess on on computed tomography scans (CT). However, the previously reported cases did not have abscess or fluid collection on retropharyngeal aspiration. Therefore, false-positive neck CT scans have been obtained, until recently. In this case, suspected neck abscess in patients with KD unresponsive to intravenous immunoglobulin could signal the possible coexistence of suppurative cervical lymphadenitis.

The systemic and pulmonary immune response to staphylococcal enterotoxins

In response to environmental cues the human pathogen Staphylococcus aureus synthesizes and releases proteinaceous enterotoxins. These enterotoxins are natural etiologic entities of severe food poisoning, toxic shock syndrome, and acute diseases. Staphylococcal enterotoxins are currently listed as Category B Bioterrorism Agents by the Center for Disease Control and Prevention. They are associated with respiratory illnesses, and may contribute to exacerbation of pulmonary disease. This likely stems from the ability of Staphylococcal enterotoxins to elicit powerful episodes of T cell stimulation resulting in release of pro-inflammatory cytokines. Here, we discuss the role of the immune system and potential mechanisms of disease initiation and progression.

Hospitalizations for Kawasaki syndrome among children in the United States, 1997-2007

BACKGROUND

The present study describes the rate and trends of childhood hospitalizations with Kawasaki syndrome (KS) in the United States.

METHODS

Retrospective analysis of hospitalizations with KS among children <18 years of age in the United States using the Kids' Inpatient Database (1997, 2000, 2003, and 2006) and the Nationwide Inpatient Sample (1998-2007).

RESULTS

The KS-associated hospitalization rate for children <5 years of age was 20.8 (95% CI: 18.5-23.1) per 100,000 children in 2006. Annual rates remained constant during the study period, except for a peak in 2005. In 2006, 76.8% (SE = 0.9%) of an estimated 5523 (SE = 289) KS-associated hospitalizations among children <18 years of age were <5 years of age. The mean age for all children at hospitalization was 3.0 years (SE <0.1); 25.7 months (SE = 0.3) for children <5 years of age, and 24.8 months (SE = 0.4) and 27.1 months (SE = 0.5) for boys and girls, respectively. The rate for boys was higher than that for girls (24.2 [95% CI: 21.3-27.1] and 16.8 [95% CI: 14.7-18.9], respectively). The rate for Asian/Pacific Islander children (30.3 [95% CI: 20.2-40.4]) was the highest among the racial groups.

CONCLUSIONS

The national KS-associated annual hospitalization rate for children <5 years of age from 1997 to 2007 was relatively stable and was similar to previously published rates, except for an increase in 2005. Most hospitalizations were in children <3 years of age with few hospitalizations during the first 2 months of age. Children of Asian/Pacific Islander descent had the highest hospitalization rate.

Detection of multiple superantigen genes in stools of patients with Kawasaki disease

OBJECTIVES

To investigate whether superantigens (SAgs) are involved in the development of Kawasaki disease (KD) by examining SAg genes in the stool of patients with KD.

STUDY DESIGN

Stool specimens were obtained from 60 patients with KD and 62 age-matched children (36 children with acute illness and 26 healthy children). Total DNA was extracted from these stool samples. Using polymerase chain reaction, we examined genes of 5 SAgs: streptococcal pyrogenic exotoxin-A (SPE-A), SPE-C, SPE-G, SPE-J, and toxic shock syndrome toxin-1.

RESULTS

At least 1 of the 5 SAg genes was detected in 42 (70%) specimens from patients with KD, 14 (38.9%) from the febrile group, and 7 (26.9%) from the healthy group. The detection rate between subjects with and without KD was of at least 1 of the 5 SAg genes (P < .001), and more than 2 SAg genes were significantly different (P = .002).

CONCLUSIONS

SAg may be involved in the development of KD; data suggest that multiple SAgs may trigger KD.

Infection and vasculitis

Vasculitis may be associated with infection, immunization or anti-microbial drugs. Infections are responsible for a number of different types of vasculitis. Conversely, patients with vasculitis may develop infections, which sometimes mimic relapse. The aim of this review is to summarize the various aspects of the inter-relationship between vasculitis and infection, and the physiopathological mechanisms involved, in light of our current knowledge from animal models. Currently, a causal relationship between infection and vasculitis has only been established in a few instances and many mechanisms remain hypothetical. This inter-relationship is further assessed from the point of view of clinical presentation and therapeutic options, based on case reports and prospective observational data.

Searching for the cause of Kawasaki disease--cytoplasmic inclusion bodies provide new insight

Although Kawasaki disease (KD) is the most common cause of acquired heart disease in children in the developed world, its aetiology remains unknown. In this Opinion, Anne Rowley and colleagues discuss evidence, including recently identified cytoplasmic inclusion bodies, which suggests that KD is caused by an infectious agent.

Kawasaki disease (KD) has emerged as the most common cause of acquired heart disease in children in the developed world. The cause of KD remains unknown, although an as-yet unidentified infectious agent might be responsible. By determining the causative agent, we can improve diagnosis, therapy and prevention of KD. Recently, identification of an antigen-driven IgA response that was directed at cytoplasmic inclusion bodies in KD tissues has provided new insights that could unlock the mysteries of KD.

Other Allergic Skin Disorders

In this chapter we discuss allergic skin disorders other than atopic dermatitis (AD): the urticaria-angioedema syndrome, allergic contact dermatitis (ACD), protein contact dermatitis (PCD), phytodermatitis, allergic photodermatitis and allergic vasculitis.

T cell activation profiles in Kawasaki syndrome

Superantigens (SAgs) are potent stimulators of T cells bearing specific Vbeta T cell receptors (TCR) and may play a role in the pathogenesis of Kawasaki syndrome (KS), although despite 15 years of intense study this area remains controversial. Because SAgs can cause Vbeta restricted T cell activation in the absence of Vbeta skewing the aims of this study were to describe a flow cytometric protocol to study both CD4 and CD8 Vbeta repertoires, and CD69 expression across the CD4 and CD8 Vbeta repertoire in children with KS. Sixteen children with KS were studied. There was no significant increase in overall peripheral blood CD4 or CD8 T cell activation as determined by CD69 expression. However, Vbeta restricted CD4 and/or CD8 activation was observed in eight of 11 (72%) of the KS patients, a finding not observed in healthy controls. Thirteen of 16 (81%) of the KS patients had evidence of either Vbeta skewing (particularly CD4 Vbeta2 and Vbeta5.1) and/or Vbeta restricted activation. Three patients had Vbeta restricted activation in the absence of skewing. We suggest that these preliminary observations highlight the many layers of complexity when considering T cell activation in KS, which could explain some of the conflicting studies regarding peripheral blood T cell activation and Vbeta skewing. It is likely that in order to move forward with this debate a combination of detailed microbiological, immunological and molecular techniques applied to individual patients will be required ultimately to prove or refute the SAg hypothesis of KS.

The role of superantigens of group A Streptococcus and Staphylococcus aureus in Kawasaki disease

PURPOSE OF REVIEW

Since the first suggestion of a superantigen hypothesis for Kawasaki disease over a decade ago, debate on the aetiology remains inconclusive. This article reviews recent publications that address the role of superantigens of group A Streptococcus and Staphylococcus aureus in the pathogenesis of Kawasaki disease.

RECENT FINDINGS

Over the past few years, new superantigens produced by group A Streptococcus and S. aureus have been increasingly identified, bringing the total known number to more than 30. Several studies on T-cell Vbeta repertoires and seroloepidemiology have demonstrated evidence for the involvement of single or multiple superantigens produced by the two pathogens. The associated superantigens differed in those studies, including streptococcal pyrogenic toxins A and C, staphylococcal enterotoxins A-C, and toxic shock syndrome toxin 1. These disparate findings suggest that the inflammation of Kawasaki disease does not result from a single agent but rather a final common inflammatory pathway in genetically susceptible individuals after numerous infectious agents.

SUMMARY

Certain staphylococcal and streptococcal superantigens are suggested to be responsible for the development of Kawasaki disease. A better understanding of the precise role of the causative agents will lead to accurate diagnosis, more targeted therapy and an improvement of coronary outcomes.

New developments in the search for the etiologic agent of Kawasaki disease

PURPOSE OF REVIEW

The aim of this article is to review recent developments in the search for the etiologic agent of Kawasaki disease.

RECENT FINDINGS

Two recently proposed theories of Kawasaki disease etiology, the toxic shock syndrome toxin-1 hypothesis and the coronavirus NL-63 hypothesis, have been studied extensively and have been disproven. Surprisingly, IgA plasma cells infiltrate inflamed tissues in acute Kawasaki disease, including the coronary artery, and are oligoclonal, or antigen-driven. Synthetic versions of predominant IgA antibodies in acute Kawasaki disease arterial tissue bind to an antigen present in acute Kawasaki disease ciliated bronchial epithelium and in a subset of macrophages in acute inflamed Kawasaki disease tissues. Light and electron microscopic studies of the antigen in acute Kawasaki disease ciliated bronchial epithelium indicate that the Kawasaki disease-associated antigen localizes to cytoplasmic inclusion bodies that are consistent with aggregates of viral protein and associated nucleic acid.

SUMMARY

The identification of cytoplasmic inclusion bodies in acute Kawasaki disease ciliated bronchial epithelium has provided direction for future Kawasaki disease etiology studies. Transmission electron microscopic examination of glutaraldehyde-fixed medium-sized bronchi from acute Kawasaki disease fatalities and analysis of the protein and nucleic acid components of the inclusions should provide important information about these inclusion bodies and speed the identification of the specific etiologic agent of Kawasaki disease.

Epidemiology and etiology of Kawasaki disease

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

Salicylate for the treatment of Kawasaki disease in children

BACKGROUND

Kawasaki disease is the most common cause of acquired heart disease in children in developed countries. The coronary arteries supplying the heart can be damaged in Kawasaki disease. The principal advantage of timely diagnosis is the potential to prevent this complication with early treatment. Salicylate (acetyl salicylate acid (ASA), aspirin) and intravenous immunoglobulin (IVIG) are widely used for this purpose. Salicylate is largely otherwise avoided in children because of concerns about serious side effects, particularly the risk of Reyes syndrome.

OBJECTIVES

The objective of this review was to evaluate the effectiveness of salicylate in treating and preventing cardiac consequences of Kawasaki disease in children.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Disease Group searched their trials register (last searched July 2006) and the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched Issue 3, 2006). We searched MEDLINE (January 1966 to July 2006), EMBASE (January 1980 to July 2006), and CINAHL (1982 to July 2006), and reference list of articles. In addition we contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of salicylate to treat Kawasaki disease in children were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

We found one trial involving 102 children which was described as randomised, but it was not possible to confirm the method of treatment allocation. A second comparative study, possibly with a randomised treatment allocation, was also identified. The one randomised trial reported no association between the addition of ASA to IVIG treatment on the rate of coronary artery abnormalities at follow up, but with wide confidence limits. The second, possibly randomised trial did demonstrate a reduction in duration of fever with high dose ASA compared to low dose ASA, but was insufficiently powered to establish the effect on coronary artery abnormalities at follow up.

AUTHORS' CONCLUSIONS

Until good quality RCTs are carried out, there is insufficient evidence to indicate whether children with Kawasaki disease should continue to receive salicylate as part of their treatment regimen.

Development of serum IgM antibodies against superantigens of Staphylococcus aureus and Streptococcus pyogenes in Kawasaki disease

To serologically determine the association of microbial superantigens and the pathogenesis of Kawasaki disease (KD), we conducted a case-control study. Serum IgG and IgM antibodies against staphylococcal enterotoxin A (SEA), SEB, SEC, toxic shock syndrome toxin-1 (TSST-1), and streptococcal pyrogenic exotoxin A (SPEA) were measured by an enzyme-linked immunosorbent assay in 293 serum samples from 65 KD patients on clinical days 1-28 and 120 control samples. The administration of immunoglobulin products, which contain high concentrations of IgG antibodies against all the superantigens, directly elevated antitoxin IgG antibodies in KD patients. In contrast, antitoxin IgM antibodies were not detected in immunoglobulin products. Actually, we found a significant elevation of IgM antibodies against SEA in KD patients in the first (median titre: 0.020, P < 0.01 versus control), second (0.024, P < 0.001), third (0.030, P < 0.001) and fourth (0.038, P < 0.001) weeks, compared to the controls (0.015). Significant differences of IgM antibodies were also true for SEB, TSST-1, and SPEA throughout the first to fourth weeks, and for SEC throughout the second to fourth weeks. The prevalence of KD patients having high IgM titres (> mean + 2SD of control values) to the 5 superantigens was increased with the clinical weeks, and reached 29-43% of KD subjects at the fourth week. This is the first study that describes kinetics of IgM antibodies against superantigens and clarifies the serological significance throughout the clinical course of KD. Our results suggest that multiple superantigens involve in the pathogenesis of KD.

Kawasaki disease: what is the epidemiology telling us about the etiology?

Kawasaki disease (KD) is an important and common inflammatory vasculitis of early childhood with a striking predilection for the coronary arteries. It is the predominant cause of paediatric acquired heart disease in developed countries. Despite 40 years of research, the aetiology of KD remains unknown and consequently there is no diagnostic test and treatment is non-specific and sub-optimal. The consensus is that KD is due to one or more widely distributed infectious agent(s), which evoke an abnormal immunological response in genetically susceptible individuals. The epidemiology of KD has been extensively investigated in many populations and provides much of the supporting evidence for the consensus regarding etiology. These epidemiological data are reviewed here, in the context of the etiopathogenesis. It is suggested that these data provide additional clues regarding the cause of KD and may account for some of the continuing controversies in the field.

The epidemiology of Kawasaki disease in an urban hospital: does African American race protect against coronary artery aneurysms?

The etiology and pathogenesis of Kawasaki disease (KD) is largely unknown. Certain demographic factors and laboratory findings are predictive of the development of coronary artery (CA) aneurysms. The objectives of this study were to determine the epidemiology of KD patients in an urban hospital and determine risk factors associated with their development of CA abnormalities. A longitudinal case series of KD patients admitted to Children's National Medical Center from 1990 to 2002 was examined. Age, sex, ethnic background, duration of fever prior to diagnosis, address, month diagnosed, and CA abnormalities (ectasia or aneurysms) on echocardiography were recorded. Median household income was obtained from the U.S. Census Bureau Web site. The Student t-test, logistic regression analyses, and the Kruskal-Wallis test were used, with significance assumed at p < 0.05. A total of 302 patients were evaluated. CA abnormalties were found in 27 patients (9%), with aneurysms identified in 13 patients (4%). Age was 2.9 +/- 2.4 years (range, 2 months to 14 years). A total of 51 patients (16%) were < or =1 year and 35 patients (12%) were > or =5 years. Ethnic distribution was 54% (164) African American, 24% (72) Caucasian, 9% (29) Asian/Pacific Islander, 8% (23) Hispanic, and 5% (14) Middle Eastern. Only 2/164 (1.2%) African Americans developed CA aneurysms. Neighborhood median income of the cohort was $45,400 +/- $21,200 ($52,200 +/-$25,800 for patients with aneurysms). A total of 28% of cases clustered between December and January. Cases doubled annually in 1999-2001 compared to 1990-1998 (39 vs 19). Multivariate logistic regression found age between 1 and 5 years [p = 0.045; odds ratio, 0.31; 95% confidence interval (CI), 0.10-0.97] and African American race (p = 0.014; odds ratio, 0.15; 95% CI, 0.03-0.68) to be independently protective against CA aneurysms. Duration of fever prior to diagnosis, considered in 210 patients, was different between patients with and without aneurysms (11 +/- 5.3 vs 6.5 +/- 3.8 days, respectively, p = 0.0007). Multivariate logistic regression found fever longer than 5 days to be the only predictive factor associated with the development of aneurysms and any abnormality. African Americans had a shorter duration of fever than the rest of the cohort (6.03 vs 7.31 days), (p = 0.0087). The epidemiology of KD at our hospital is similar to that at other centers except for the predominance of African Americans with a shorter duration of fever prior to diagnosis and a decreased incidence of CA aneurysms compared to other ethnicities. The protective nature of African American ethnicity against the development of CA aneurysms raises speculation about the role of genetics and its interaction with immunity in the pathogenesis of KD.

Pathogénie des vascularites systémiques primitives (II): vascularites ANCA-négatives

The pathogenesis of different types of systemic vasculitis negative for antineutrophil cytoplasm antibodies (ANCA) and involving small or medium-sized vessels is not very well documented. During polyarteritis nodosa (PAN), which is related to hepatitis B virus (HBV) infection, as well as during cryoglobulinemic vasculitides, associated with hepatitis C virus (HCV), and probably during Henoch Schönlein purpura, histological lesions may result from the deposition of immune complexes formed from viral antigens and from antibodies responsible for the activation of the classic complement pathway and for recruitment of polymorphonuclear neutrophils. Two other mechanisms are discussed for other types of ANCA-negative systemic vasculitis: immune complex deposition and sheer stress at arterial bifurcation points. A bacterial superantigen is suspected in Kawasaki disease but remains unproved.

Absence of hypercoagulability in acute Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a systemic vasculitis syndrome with the striking feature of cardiovascular involvement. Endothelial cell (EC) damage has been suggested to predispose individuals to the development of coronary vascular disorders. When EC are perturbed, prethrombotic complications ensue. The purpose of this study was to examine the clinical relevance of EC activation and hypercoagulability in the pathogenesis of KD and to determine if plasma levels of these markers are correlated with the development of coronary aneurysms.

METHODS

EC function and coagulation status were assessed in 52 patients with acute KD, 20 febrile control subjects, and 20 healthy control subjects. Biological markers of EC and hypercoagulability were measured and included thrombomodulin, tissue factor, tissue factor pathway inhibitor, von Willebrand factor (vWF), coagulation factor VII (FVII), activated factor VII, prothrombin fragment 1 + 2 (F1 + 2), and D-dimer.

RESULTS

Transient dilatation of coronary arteries was the most common complication (55.8%), and coronary aneurysm was noted in five patients (9.6%). Levels of vWF, FVII, F1 + 2 and D-dimer were higher in acute KD patients compared with healthy controls but not febrile controls. Markers of EC and hypercoagulability were not different between patients with cardiac complications and those without cardiac complications. Biological and immunological assays did not demonstrate the prethrombotic state in acute KD.

CONCLUSIONS

Our results suggest that hypercoagulability does not occur during the acute stage of KD. Markers of EC damage and hypercoagulability are not predictive of coronary aneurysms in KD.