Kawasaki disease (KD) is a childhood vasculitis with a predilection for the coronary arteries (CA). The etiology of KD is unknown; however, superantigens (SAg) have been implicated. SAg-activated T cells undergo massive proliferation followed by apoptosis; conversely, in KD these T cells may persist and target the CAs. Enhanced costimulation can rescue SAg-activated T cells from apoptosis, and Toll-like receptor 2 (TLR2) enhances costimulation. In a murine model of KD, TLR2-deficient mice are disease resistant, and evidence suggests preferential expression of TLR2 at the CA. Results from this study demonstrate that TLR2 is rapidly expressed in the heart following disease induction, and that TLR2 is expressed differentially in various arteries. The aorta, from which the CAs branch off, expressed the highest TLR2 levels. A microvascular endothelial cell line was shown to function as an APC following TLR2 stimulation, supporting the proliferation of SAg-activated T cells and their rescue from apoptosis.

Kawasaki disease (KD) is an acute inflammatory disease characterized by persistent inflammation of the coronary arteries. KD is characterized by the release of cytokines such as tumor necrosis factor alpha (TNFα) and is thought to be initiated by a superantigen (SAg). The Lactobacillus casei cell wall extract model of KD demonstrates a critical requirement for TNFα and its receptor during pathogenesis, although the precise effect of TNFα is unknown. A persistent T cell infiltrate in the coronary artery disagrees with established fates of SAg activated cells, which undergo apoptosis. In this work, TNFα was found to promote the survival of SAg-reactive T cells. The results demonstrate that TNFα regulates B7.2 molecule expression on antigen presenting cells, and that TNFα indirectly promotes the survival of SEB-stimulated T cells by driving costimulation. These observations demonstrate how TNFα prevents T cell apoptosis and lend support to KD therapies which target TNFα and B7.

Kawasaki disease (KD) is a childhood vasculitis with a predilection for the coronary arteries (CA). The etiology of KD is unknown; however, superantigens (SAg) have been implicated. SAg-activated T cells undergo massive proliferation followed by apoptosis; conversely, in KD these T cells may persist and target the CAs. Enhanced costimulation can rescue SAg-activated T cells from apoptosis, and Toll-like receptor 2 (TLR2) enhances costimulation. In a murine model of KD, TLR2-deficient mice are disease resistant, and evidence suggests preferential expression of TLR2 at the CA. Results from this study demonstrate that TLR2 is rapidly expressed in the heart following disease induction, and that TLR2 is expressed differentially in various arteries. The aorta, from which the CAs branch off, expressed the highest TLR2 levels. A microvascular endothelial cell line was shown to function as an APC following TLR2 stimulation, supporting the proliferation of SAg-activated T cells and their rescue from apoptosis.

Kawasaki disease (KD) is a multisystem vasculitis that results in localized coronary artery elastin breakdown and aneurysm formation. It is the leading cause of acquired heart disease of children in North America. Despite conventional treatment, a significant proportion of patients continue to develop coronary sequelae. The mechanisms of arterial aneurysm formation in KD are not known. Using a murine model of KD, Lactobacillus casei cell wall extract-induced coronary arteritis, the processes leading to coronary aneurysm formation were examined. Vessel damage occurred as a result of the increased enzymatic activity of the elastase, matrix metalloproteinase (MMP)-9. MMP-9 protein and activity levels were elevated in the heart post-disease induction. Expression and activity were specific for and localized to inflamed coronary arteries. The pro-inflammatory cytokine, tumour necrosis factor (TNF)-α, was required for increasing local MMP-9 expression. Importantly, MMP-9-deficient animals had a significantly reduced incidence of elastin breakdown. Furthermore, in a cohort of KD patients, serum MMP-9 did not correlate with coronary outcome, highlighting the importance of local expression of this elastase. Intravenous immunoglobulin (IVIG) and aspirin/salicylate are therapeutic agents in current use for the treatment of KD, though their exact mechanisms of action in KD are not known. The biologic effects of IVIG and salicylate on critical stages of disease development were examined. IVIG and salicylate had differential effects on TNF-α expression, with therapeutic concentrations of IVIG inhibiting, and salicylate inducing, TNF-α expression leading to an indirect modulation of MMP-9 expression. Interestingly, TNF-α expression and MMP-9 activity were both directly inhibited by the metal-chelating drug doxycycline. Treatment of affected mice with doxycycline significantly improved coronary outcome. Inhibiting both the inflammatory response as well as the downstream effects of inflammation were of therapeutic value in this model of KD. These results taken together demonstrate the importance of MMP-9 in the pathogenesis of coronary artery aneurysms in KD. Targeting MMP activity holds the promise of transforming KD from the leading cause of acquired heart disease to a self-limited febrile illness.

Kawasaki disease (KD) is the most common cause of paediatric acquired heart disease, which may be attributed to the combined effects of infection, immunological response, and genetic susceptibility. The most severe complication in KD is acute coronary artery lesions (CALs), including myocardial infarction and coronary artery aneurysms. Mounting evidence indicates that adhesion molecules and chemokines play an important role in inflammation and cardiovascular disease on basis of pathogenesis. Thus, this study aimed to investigate the association of seven single nucleotide polymorphisms (SNPs) of adhesion molecules and chemokines (P-selectin 290G>A, PSGL-1 62G>A, MCP-1 -2518A>G, SDF-1 -801G>A, PECAM-1 L125V, PECAM-1 S563N and PECAM-1 R670G) with the risk of KD, sequelae of CALs and initial intravenous immunoglobulin (IVIG) treatment failure. A total of 301 KD children (185 without acute and chronic CALs, 81 with acute but without chronic CALs, and 33 with acute and chronic CALs) and 246 sex-matched healthy controls were recruited in the case-control study. In addition, 166 cases from the above KD children and 332 parents were recruited to carry out case-parent trio study. We found that PECAM-1 3 SNPs polymorphisms were not associated with above several risks, except for CALs in chronic stage. As compared with non-Leu-Ser-Arg haplotype, Leu-Ser-Arg haplotype was associated with a significant increased risk for CALs in the chronic stage (AOR 2.50, 95% CI 1.05-6.00, P=0.039). Analyses based on the diplotypes of PECAM-1 also showed that Leu-Ser-Arg allele had a significant increased risk of CALs in chronic stage in dominant manner (AOR 2.98, 95% CI 1.15-7.72, P=0.024). In addition, carriers of Leu-Ser-Arg allele had significant increased counts of platelet (¡Ñ1000/Cumm) (672.6¡Ó207.6 versus 563.1¡Ó196.8; P=0.027) within 10 days of diagnosis of KD. Moreover, we also found a significant correlation between each SNP and polymorphonuclear neutrophil counts by genotype analysis. As for other genes, there were no markedly different outcomes regardless of the risk of KD, sequelae of CALs or initial IVIG treatment failure. In conclusion, the haplotype Leu-Ser-Arg of PECAM-1 is a genetic marker of susceptibility to sequelae of chronic CALs for KD patients. However, the role of PECAM-1 SNPs in CALs formation in the chronic stage in KD patients still needs further evaluation.

Kawasaki disease (KD) is the most common cause of paediatric acquired heart disease which may be attributed to the combined effects of infection, immunological response, and genetic susceptibility. Acute coronary artery lesions (CALs) develop in 20-48 % KD children. In addition, chronic CALs develop in approximately 20-30% of untreated KD children. Although KD children treated with IVIG, 2-6% still develop chronic CALs. According to recent epidemiological studies, Asian populations have a much higher incidence of KD. Taiwan has the third highest annual incidence in the world (69 per 100,000 children < 5 years of age between 2003 and 2006). Several studies have shown that KD patients spontaneously produce high levels of IL- 10. Plasma or serum IL-10 levels of KD children in acute phase were nearly 8-33 fold and 4-5 fold higher than those of healthy controls and those of the acute febrile children, respectively. The elevated IL-10 levels during the acute phase of KD not only decreased during subacute and convalescent phase, but also decreased immediately after IVIG administration, coincidently rapid improvement of inflammatory symptoms. The above studies show a correlation of high IL-10 levels with inflammatory features of KD, but do not answer the question of whether high levels of IL-10 may be simply a byproduct of acute KD, or whether it may play a role in the pathogenesis of KD. Therefore, a family-based linkage study of 134 case-parents trios, a case-control study of 247 KD children and 129 normal controls, and a matched case-control study of 76 KD cases with acute coronary artery lesions (CALs) and 76 KD controls without acute CALs were carried out to evaluate the association of genetic single nucleotide polymorphisms (SNP) in IL-10 promoter (-1082, -819, and -592) with the risk of KD and acute CALs. Based on the Transmission Disequilibrium test (TDT) results, significant undertransmission of haplotype ATA and overtransmission of haplotype (ACC+GCC) were found for KD (p = 0.023 and 0.011, respectively), even after 1,000 times permutation (p = 0.026 and 0.010, respectively). In addition, the TC and CC genotype of IL-10-819T>C were significantly associated with the decreased risk of acute CALs (AOR, 0.93; 95% CI, 0.47-1.81 and AOR, 0.07; 95% CI, 0.01-0.62, respectively), as compared to TT genotype. The carries of AC and CC genotype in IL-10-592A>C were with significantly decreased risk of acute CALs (AOR, 0.90; 95%CI, 0.46-1.75 and AOR, 0.17; 95%CI, 0.03-0.87, respectively), as compared to those with AA genotype. Furthermore, as compared with ATA/ATA diplotype, GCC+ACC/GCC+ACC diplotype of IL10 was associated with the decreased risk of acute CALs (AOR, 0.18; 95% CI, 0.04-0.72). In conclusion, the haplotype and diplotype of IL10-1082/-819/-592 were significant differences in the transmission in KD families and that the IL10-819 and -592 SNPs played important role for the sequelae of acute CALs.

Kawasaki Disease (KD) is a childhood disease leading to coronary arteritis. Elevated numbers of CD40L+ platelets in circulation is correlated with risk of heart damage. CD40L is a tumor necrosis family member that binds to CD40 and αIIbβ3, receptors which are also expressed on platelets. A single injection of Lactobacillus casei Cell Wall Extract (LCWE) induces a disease similar to KD in mice, where LCWE superantigen (SAg) reactive T-cells persist in the coronary artery. This phenotype is inconsistent with the fate of SAg-stimulated cells and is likely mediated by co-stimulation. This work shows that stimulation with a SAg induces platelet activation and CD40L expression in vitro. Furthermore, enhanced survival of SAg-reactive T-cells is demonstrated following antibody-mediated CD40L cross-linking. This effect is mediated via inhibition of the extrinsic apoptosis pathway. In addition, CD40 cross-linking is also reported to enhance SAg-reactive T-cell survival by enhancing CD86 expression on APCs and CD28 co-stimulation.

Kawasaki Disease (KD) is a childhood disease leading to coronary arteritis. Elevated numbers of CD40L+ platelets in circulation is correlated with risk of heart damage. CD40L is a tumor necrosis family member that binds to CD40 and αIIbβ3, receptors which are also expressed on platelets. A single injection of Lactobacillus casei Cell Wall Extract (LCWE) induces a disease similar to KD in mice, where LCWE superantigen (SAg) reactive T-cells persist in the coronary artery. This phenotype is inconsistent with the fate of SAg-stimulated cells and is likely mediated by co-stimulation. This work shows that stimulation with a SAg induces platelet activation and CD40L expression in vitro. Furthermore, enhanced survival of SAg-reactive T-cells is demonstrated following antibody-mediated CD40L cross-linking. This effect is mediated via inhibition of the extrinsic apoptosis pathway. In addition, CD40 cross-linking is also reported to enhance SAg-reactive T-cell survival by enhancing CD86 expression on APCs and CD28 co-stimulation.

Kawasaki disease (KD) is a multisystem vasculitis that results in localized coronary artery elastin breakdown and aneurysm formation. It is the leading cause of acquired heart disease of children in North America. Despite conventional treatment, a significant proportion of patients continue to develop coronary sequelae. The mechanisms of arterial aneurysm formation in KD are not known. Using a murine model of KD, Lactobacillus casei cell wall extract-induced coronary arteritis, the processes leading to coronary aneurysm formation were examined. Vessel damage occurred as a result of the increased enzymatic activity of the elastase, matrix metalloproteinase (MMP)-9. MMP-9 protein and activity levels were elevated in the heart post-disease induction. Expression and activity were specific for and localized to inflamed coronary arteries. The pro-inflammatory cytokine, tumour necrosis factor (TNF)-α, was required for increasing local MMP-9 expression. Importantly, MMP-9-deficient animals had a significantly reduced incidence of elastin breakdown. Furthermore, in a cohort of KD patients, serum MMP-9 did not correlate with coronary outcome, highlighting the importance of local expression of this elastase. Intravenous immunoglobulin (IVIG) and aspirin/salicylate are therapeutic agents in current use for the treatment of KD, though their exact mechanisms of action in KD are not known. The biologic effects of IVIG and salicylate on critical stages of disease development were examined. IVIG and salicylate had differential effects on TNF-α expression, with therapeutic concentrations of IVIG inhibiting, and salicylate inducing, TNF-α expression leading to an indirect modulation of MMP-9 expression. Interestingly, TNF-α expression and MMP-9 activity were both directly inhibited by the metal-chelating drug doxycycline. Treatment of affected mice with doxycycline significantly improved coronary outcome. Inhibiting both the inflammatory response as well as the downstream effects of inflammation were of therapeutic value in this model of KD. These results taken together demonstrate the importance of MMP-9 in the pathogenesis of coronary artery aneurysms in KD. Targeting MMP activity holds the promise of transforming KD from the leading cause of acquired heart disease to a self-limited febrile illness.

Presentation: A 3 month-old male is referred for admission with a 2-day history of fever, having been diagnosed with pneumonia and prescribed a cephalosporin on the previous day. A blood culture obtained at that time is positive for coagulase negative Staphyloccocus. On exam, he is ill-appearing. He has bilateral conjunctivitis that spares the limbus, non-exudative pharyngitis, and a polymorphic truncal rash. There is no appreciable cervical lymphadenopathy or extremity involvement. A chest x-ray demonstrates a round infiltrate of the left upper lobe, and initial labs reveal a white blood count of 17.5, a C-reactive protein (CRP) of 23.9 mg/dL, and a normal comprehensive metabolic panel. His positive blood culture is deemed a contaminant, and antibiotic coverage for community-acquired pneumonia is given with ampicillin. Diagnostic evaluation: On day 5 of illness, his fevers persist despite broadened antibiotic coverage. Further work-up has ruled out viral respiratory pathogens and Epstein-Barr virus as a cause of persistent fevers. Incomplete Kawasaki disease is suspected due to continued fevers, the presence of three clinical criteria, and further increase in his CRP. He lacks other supplemental laboratory criteria, so an echocardiogram is obtained that shows mild dilation of the left anterior descending artery (LAD) of indeterminate significance. A repeat echocardiogram 2 days later reveals progressive dilation of left main coronary artery (LMCA), LAD, and right coronary artery (RCA). Diagnosis: Dilation of the LAD and RCA confirm a diagnosis of incomplete Kawasaki disease. Within 48 hours of treatment with IVIG and high-dose aspirin, the patient is afebrile with resolving symptoms and a declining CRP. He is discharged on the 9th day of illness on low dose aspirin and a cephalosporin to complete an antibiotic course for concurrent pneumonia. Conclusion & Discussion: This case illustrates the importance of maintaining a high index of suspicion for an incomplete presentation of Kawasaki disease, particularly among infants. The American Heart Association’s guidelines were updated in 2017 to improve recognition of incomplete Kawasaki disease, particularly among infants who are more likely to have an incomplete presentation, abnormalities of the coronary arteries, and a delayed diagnosis. The key to this patient’s diagnosis was the presence of a bilateral conjunctivitis that spared the limbus. A bilateral, non-exudative conjunctivitis that spares the limbus has been recognized as a feature suggestive of Kawasaki disease for the better part of four decades; our review of the literature suggests this feature is highly specific to the diagnosis of Kawasaki disease.