Regulatory T Cells in Autoimmune Vasculitis

Blood vessels are indispensable for host survival and are protected from inappropriate inflammation by immune privilege. This protection is lost in patients with autoimmune vasculitides, a heterogeneous group of diseases causing damage to arteries, arterioles, and capillaries. Vasculitis leads to vascular wall destruction and/or luminal occlusion, resulting in hemorrhage and tissue ischemia. Failure in the quantity and quality of immunosuppressive regulatory T cells (Treg) has been implicated in the breakdown of the vascular immune privilege. Emerging data suggest that Treg deficiencies are disease-specific, affecting distinct pathways in distinct vasculitides. Mechanistic studies have identified faulty CD8+ Tregs in Giant Cell Arteritis (GCA), a vasculitis of the aorta and the large aortic branch vessels. Specifically, aberrant signaling through the NOTCH4 receptor expressed on CD8+ Treg cells leads to rerouting of intracellular vesicle trafficking and failure in the release of immunosuppressive exosomes, ultimately boosting inflammatory attack to medium and large arteries. In Kawasaki’s disease, a medium vessel vasculitis targeting the coronary arteries, aberrant expression of miR-155 and dysregulated STAT5 signaling have been implicated in undermining CD4+ Treg function. Explorations of mechanisms leading to insufficient immunosuppression and uncontrolled vascular inflammation hold the promise to discover novel therapeutic interventions that could potentially restore the immune privilege of blood vessels and pave the way for urgently needed innovations in vasculitis management.

Characterization of SARS-CoV-2 and common cold coronavirus-specific T-cell responses in MIS-C and Kawasaki disease children

The immunopathogenesis of multisystem inflammatory syndrome (MIS-C) in children that may follow exposure to SARS-CoV-2 is incompletely understood. Here, we studied SARS-CoV-2-specific T cells in MIS-C, Kawasaki disease (KD), and SARS-CoV-2 convalescent controls using peptide pools derived from SARS-CoV-2 spike or nonspike proteins, and common cold coronaviruses (CCC). Coordinated CD4+ and CD8+ SARS-CoV-2-specific T cells were detected in five MIS-C subjects with cross-reactivity to CCC. CD4+ and CD8+ T-cell responses alone were documented in three and one subjects, respectively. T-cell specificities in MIS-C did not correlate with disease severity and were similar to SARS-CoV-2 convalescent controls. T-cell memory and cross-reactivity to CCC in MIS-C and SARS-CoV-2 convalescent controls were also similar. The chemokine receptor CCR6, but not CCR9, was highly expressed on SARS-CoV-2-specific CD4+ but not on CD8+ T cells. Only two of 10 KD subjects showed a T-cell response to CCC. Enumeration of myeloid APCs revealed low cell precursors in MIS-C subjects compared to KD. In summary, children with MIS-C mount a normal T-cell response to SARS-CoV-2 with no apparent relationship to antecedent CCC exposure. Low numbers of tolerogenic myeloid DCs may impair their anti-inflammatory response.

Hygiene Hypothesis as the Etiology of Kawasaki Disease: Dysregulation of Early B Cell Development

Kawasaki disease (KD) is an acute systemic vasculitis that occurs predominantly in children under 5 years of age. Despite much study, the etiology of KD remains unknown. However, epidemiological and immunological data support the hygiene hypothesis as a possible etiology. It is thought that more sterile or clean modern living environments due to increased use of sanitizing agents, antibiotics, and formula feeding result in a lack of immunological challenges, leading to defective or dysregulated B cell development, accompanied by low IgG and high IgE levels. A lack of B cell immunity may increase sensitivity to unknown environmental triggers that are nonpathogenic in healthy individuals. Genetic studies of KD show that all of the KD susceptibility genes identified by genome-wide association studies are involved in B cell development and function, particularly in early B cell development (from the pro-B to pre-B cell stage). The fact that intravenous immunoglobulin is an effective therapy for KD supports this hypothesis. In this review, I discuss clinical, epidemiological, immunological, and genetic studies showing that the etiopathogenesis of KD in infants and toddlers can be explained by the hygiene hypothesis, and particularly by defects or dysregulation during early B cell development.

The autoimmune signature of hyperinflammatory multisystem inflammatory syndrome in children

Multisystem inflammatory syndrome in children (MIS-C) manifests as a severe and uncontrolled inflammatory response with multiorgan involvement, occurring weeks after SARS-CoV-2 infection. Here, we utilized proteomics, RNA sequencing, autoantibody arrays, and B cell receptor (BCR) repertoire analysis to characterize MIS-C immunopathogenesis and identify factors contributing to severe manifestations and intensive care unit admission. Inflammation markers, humoral immune responses, neutrophil activation, and complement and coagulation pathways were highly enriched in MIS-C patient serum, with a more hyperinflammatory profile in severe than in mild MIS-C cases. We identified a strong autoimmune signature in MIS-C, with autoantibodies targeted to both ubiquitously expressed and tissue-specific antigens, suggesting autoantigen release and excessive antigenic drive may result from systemic tissue damage. We further identified a cluster of patients with enhanced neutrophil responses as well as high anti-Spike IgG and autoantibody titers. BCR sequencing of these patients identified a strong imprint of antigenic drive with substantial BCR sequence connectivity and usage of autoimmunity-associated immunoglobulin heavy chain variable region (IGHV) genes. This cluster was linked to a TRBV11-2 expanded T cell receptor (TCR) repertoire, consistent with previous studies indicating a superantigen-driven pathogenic process. Overall, we identify a combination of pathogenic pathways that culminate in MIS-C and may inform treatment.

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.

Downregulation of exhausted cytotoxic T cells in gene expression networks of multisystem inflammatory syndrome in children

Multisystem inflammatory syndrome in children (MIS-C) presents with fever, inflammation and pathology of multiple organs in individuals under 21 years of age in the weeks following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although an autoimmune pathogenesis has been proposed, the genes, pathways and cell types causal to this new disease remain unknown. Here we perform RNA sequencing of blood from patients with MIS-C and controls to find disease-associated genes clustered in a co-expression module annotated to CD56dimCD57+ natural killer (NK) cells and exhausted CD8+ T cells. A similar transcriptome signature is replicated in an independent cohort of Kawasaki disease (KD), the related condition after which MIS-C was initially named. Probing a probabilistic causal network previously constructed from over 1,000 blood transcriptomes both validates the structure of this module and reveals nine key regulators, including TBX21, a central coordinator of exhausted CD8+ T cell differentiation. Together, this unbiased, transcriptome-wide survey implicates downregulation of NK cells and cytotoxic T cell exhaustion in the pathogenesis of MIS-C.

The Emerging Role of Neutrophils in the Pathogenesis of Thrombosis in COVID-19

Previous studies have shown that COVID-19 leads to thrombotic complications, which have been associated with high morbidity and mortality rates. Neutrophils are the largest population of white blood cells and play a pivotal role in innate immunity. During an infection, neutrophils migrate from circulation to the infection site, contributing to killing pathogens. This mechanism is regulated by chemokines such as IL-8. Moreover, it was shown that neutrophils play an important role in thromboinflammation. Through a diverse repertoire of mechanisms, neutrophils, apart from directly killing pathogens, are able to activate the formation of thrombi. In COVID-19 patients, neutrophil activation promotes neutrophil extracellular trap (NET) formation, platelet aggregation, and cell damage. Furthermore, neutrophils participate in the pathogenesis of endothelitis. Overall, this review summarizes recent progress in research on the pathogenesis of COVID-19, highlighting the role of the prothrombotic action of neutrophils in NET formation.

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

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

Phenotype, Susceptibility, Autoimmunity, and Immunotherapy Between Kawasaki Disease and Coronavirus Disease-19 Associated Multisystem Inflammatory Syndrome in Children

Coronavirus disease-19 (COVID-19) in children is usually mild but some are susceptible to a Kawasaki disease (KD)-like multisystem inflammatory syndrome in children (MIS-C) in the convalescent stage, posing a need to differentiate the phenotype, susceptibility, autoimmunity, and immunotherapy between KD and MIS-C, particularly in the upcoming mass vaccination of COVID-19. Patients with MIS-C are prone to gastrointestinal symptoms, coagulopathy, and shock in addition to atypical KD syndrome with fever, mucocutaneous lesions, lymphadenopathy, and/or cardiovascular events. MIS-C manifests KD-like symptoms that alert physicians to early recognize and adopt the KD treatment regimen for patients with MIS-C. MIS-C linked to COVID-19 teaches us infection-associated autoimmune vasculitis and vice versa. Studies on genetic susceptibility have identified certain human leukocyte antigen (HLA) locus and toll-like receptor (TLR) associated with KD and/or COVID-19. Certain HLA subtypes, such as HLA-DRB1 and HLA-MICA A4 are associated with KD. HLA-B*46:01 is proposed to be the risk allele of severe COVID-19 infection, and blood group O type is a protective factor of COVID-19. The autoimmune vasculitis of KD, KD shock syndrome (KDSS), or MIS-C is mediated by a genetic variant of HLA, FcγR, and/or antibody-dependent enhancement (ADE) resulting in hyperinflammation with T helper 17 (Th17)/Treg imbalance with augmented Th17/Th1 mediators: interleukin-6 (IL-6), IL-10, inducible protein-10 (IP-10), Interferon (IFNγ), and IL-17A, and lower expression of Treg-signaling molecules, FoxP3, and transforming growth factor (TGF-β). There are certain similarities and differences in phenotypes, susceptibility, and pathogenesis of KD, KDSS, and MIS-C, by which a physician can make early protection, prevention, and precision treatment of the diseases. The evolution of immunotherapies for the diseases has shown that intravenous immunoglobulin (IVIG) alone or combined with corticosteroids is the standard treatment for KD, KDSS, and MIS-C. However, a certain portion of patients who revealed a treatment resistance to IVIG or IVIG plus corticosteroids, posing a need to early identify the immunopathogenesis, to protect hosts with genetic susceptibility, and to combat Th17/Treg imbalance by anti-cytokine or pro-Treg for reversal of the hyperinflammation and IVIG resistance. Based on physiological and pathological immunity of the diseases under genetic susceptibility and host milieu conditions, a series of sequential regimens are provided to develop a so-called "Know thyself, enemy (pathogen), and ever-victorious" strategy for the prevention and immunotherapy of KD and/or MIS-C.

Identification of key signaling pathways induced by SARS-CoV2 that underlie thrombosis and vascular injury in COVID-19 patients

The SARS-CoV-2 pandemic has led to hundreds of thousands of deaths and billions of dollars in economic damage. The immune response elicited from this virus is poorly understood. An alarming number of cases have arisen where COVID-19 patients develop complications on top of the symptoms already associated with SARS, such as thrombosis, injuries of vascular system, kidney, and liver, as well as Kawasaki disease. In this review, a bioinformatics approach was used to elucidate the immune response triggered by SARS-CoV-2 infection in primary human lung epithelial and transformed human lung alveolar. Additionally, examined the potential mechanism behind several complications that have been associated with COVID-19 and determined that a specific cytokine storm is leading to excessive neutrophil recruitment. These neutrophils are directly leading to thrombosis, organ damage, and complement activation via neutrophil extracellular trap release.

High-Throughput Screening of Kawasaki Disease Sera for Antiviral Antibodies

Clinical features of Kawasaki disease (KD) display overlap with common pediatric viral illnesses, leading some to hypothesize that a viral infection is the inciting event for KD. To investigate viral infection history in KD patients, we performed comprehensive serological profiling using a high-throughput phage immunoprecipitation sequencing assay covering the complete reference protein sequences of known viruses with human tropism. KD and matched febrile control sera did not demonstrate differences in antiviral antibody profiles. We conclude that in the acute and subacute phases of disease, KD patients do not exhibit serologic evidence of exposure to known viruses that differs from controls.

COVID-19 and multisystem inflammatory syndrome in children and adolescents

As severe acute respiratory syndrome coronavirus 2 continues to spread worldwide, there have been increasing reports from Europe, North America, Asia, and Latin America describing children and adolescents with COVID-19-associated multisystem inflammatory conditions. However, the association between multisystem inflammatory syndrome in children and COVID-19 is still unknown. We review the epidemiology, causes, clinical features, and current treatment protocols for multisystem inflammatory syndrome in children and adolescents associated with COVID-19. We also discuss the possible underlying pathophysiological mechanisms for COVID-19-induced inflammatory processes, which can lead to organ damage in paediatric patients who are severely ill. These insights provide evidence for the need to develop a clear case definition and treatment protocol for this new condition and also shed light on future therapeutic interventions and the potential for vaccine development. TRANSLATIONS: For the French, Chinese, Arabic, Spanish and Russian translations of the abstract see Supplementary Materials section.

Clinical Significance of Serum Soluble TNF Receptor I/II Ratio for the Differential Diagnosis of Tumor Necrosis Factor Receptor-Associated Periodic Syndrome From Other Autoinflammatory Diseases

Objectives: Genetic analysis of TNFRSF1A can confirm the diagnosis of tumor necrosis factor receptor-associated periodic syndrome (TRAPS), but interpretation of the pathogenesis of variants of unknown significance is sometimes required. The aim of this study was to evaluate the clinical significance of serum soluble tumor necrosis factor receptor type I (sTNFR-I)/II ratio to differentiate TRAPS from other autoinflammatory diseases. Methods: Serum sTNFR-I and sTNFR-II levels were measured using an enzyme-linked immunosorbent assay in patients with TRAPS (n = 5), familial Mediterranean fever (FMF) (n = 14), systemic juvenile idiopathic arthritis (s-JIA) (n = 90), and Kawasaki disease (KD) (n = 37) in the active and inactive phase, along with healthy controls (HCs) (n = 18). Results: In the active phase, the serum sTNFR-I/II ratio in patients with s-JIA, KD, and FMF was significantly elevated compared with that in HCs, whereas it was not elevated in patients with TRAPS. In the inactive phase, the serum sTNFR-I/II ratio in patients with s-JIA and FMF was significantly higher compared with that in HCs, and the ratio was lower in TRAPS patients than in patients with s-JIA and FMF. Conclusions: Low serum sTNFR-I/II ratio in the active and inactive phase might be useful for the differential diagnosis of TRAPS and other autoinflammatory diseases.

Kawasaki-like disease in children with COVID-19: A hypothesis

With rapid spread of severe acute respiratory syndrome- corona virus-2 (SARS-COV-2) globally, some new aspects of the disease have been reported. Recently, it has been reported the incidence of Kawasaki-like disease among children with COVID-19. Since, children had been known to be less severely affected by the virus in part due to the higher concentration of Angiotensin converting enzyme (ACE)-2 receptor, this presentation has emerged concerns regarding the infection of children with SARS-COV2. ACE2 has anti-inflammatory, anti-fibrotic and anti-proliferative characteristics through converting angiotensin (Ag)-II to Ang (1-7). ACE2 receptor is downregulated by the SARS-COV through the spike protein of SARS-CoV (SARS-S) via a process that is tightly coupled with Tumor necrosis factor (TNF)-α production. TNF-α plays a key role in aneurysmal formation of coronary arteries in Kawasaki disease (KD). Affected children by COVID-19 with genetically-susceptible to KD might have genetically under-expression of ACE2 receptor that might further decrease the expression of ACE2 due to the downregulation of the receptor by the virus in these patients. It appears that TNF- α might be the cause and the consequence of the ACE2 receptor downregulation which results in arterial walls aneurysm. Conclusion: Genetically under-expression of ACE2 receptor in children with genetically-susceptible to KD who are infected with SARS-CoV-2 possibly further downregulates the ACE2 expression by TNF-α and leads to surge of inflammation including TNF-α and progression to Kawasaki-like disease.

Autoimmune and rheumatic musculoskeletal diseases as a consequence of SARS-CoV-2 infection and its treatment

The coronavirus disease-2019 (COVID-19) pandemic is likely to pose new challenges to the rheumatology community in the near and distant future. Some of the challenges, like the severity of COVID-19 among patients on immunosuppressive agents, are predictable and are being evaluated with great care and effort across the globe. A few others, such as atypical manifestations of COVID-19 mimicking rheumatic musculoskeletal diseases (RMDs) are being reported. Like in many other viral infections, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can potentially lead to an array of rheumatological and autoimmune manifestations by molecular mimicry (cross-reacting epitope between the virus and the host), bystander killing (virus-specific CD8 + T cells migrating to the target tissues and exerting cytotoxicity), epitope spreading, viral persistence (polyclonal activation due to the constant presence of viral antigens driving immune-mediated injury) and formation of neutrophil extracellular traps. In addition, the myriad of antiviral drugs presently being tried in the treatment of COVID-19 can result in several rheumatic musculoskeletal adverse effects. In this review, we have addressed the possible spectrum and mechanisms of various autoimmune and rheumatic musculoskeletal manifestations that can be precipitated by COVID-19 infection, its therapy, and the preventive strategies to contain the infection.

COVID-19: Infection or Autoimmunity

The clinical and laboratory features of COVID-19 are reviewed with attention to the immunologic manifestations of the disease. Recent COVID-19 publications describe a variety of clinical presentations including an asymptomatic state, pneumonia, a hemophagocytic lymphohistiocytosis like syndrome, Multisystem Inflammatory Syndrome in Children (MIS-C) but, also called Pediatric Inflammatory Multisystem Syndrome-Toxic Shock (PIMS-TS), Kawasaki Disease, and myocarditis. A common theme amongst multiple reports suggests an overexuberant autoimmune component of the disease but a common pathophysiology to explain the variations in clinical presentation has been elusive. Review of the basic science of other viral induced autoimmune disorders may give clues as to why immunosuppressive and immunomodulating regimens now appear to have some efficacy in COVID-19. Review of the immunopathology also reveals other therapies that have yet to be explored. There is potential use of T cell depleting therapies and possibly anti-CD20 therapy for COVID-19 and clinical research using these medications is warranted.

Neurological involvement in Kawasaki disease: a retrospective study

BACKGROUND

Kawasaki disease (KD) is an acute, self-limiting systemic vasculitis that predominately affects children. Neurological involvement is a known complication of KD, however, its association with KD severity remains elusive. We aimed to systematically describe the general manifestations of neurological involvement in KD, determine whether neurological involvement is a marker of disease severity in patients with KD, and assess the relationship of such involvement with intravenous immunoglobulin (IVIG) resistance and coronary artery lesions (CALs).

METHODS

We retrospectively reviewed data from 1582 patients with KD between January 2013 and December 2017. Profiles of patients with neurological symptoms (group A, n = 80) were compared to those of gender- and admission date-matched patients without neurological involvement (group B, n = 512). Multivariate logistic regression analyses were performed to determine whether neurological involvement was significantly associated with IVIG resistance.

RESULTS

Neurological involvement was observed in 5.1% (80/1582) of patients with KD. The neurological manifestations were diffuse, presenting as headache (13/80, 16.3%), convulsions (14/80, 17.5%), somnolence (40/80, 50.1%), extreme irritability (21/80, 26.3%), signs of meningeal irritation (15/80, 18.8%), bulging fontanelles (7/80, 8.8%), and facial palsy (1/80, 1.3%). Neurological symptoms represented the initial and/or predominant manifestation in 47.5% (38/80) of patients with KD. The incidence of IVIG resistance and levels of inflammatory markers were higher in group A than in group B. However, neurological involvement was not an independent risk factor for IVIG resistance or CALs.

CONCLUSION

Rates of neurological involvement were relatively low in patients with KD. Neurological involvement was associated with an increased risk of IVIG resistance and severe inflammatory burden. Our results highlight the need for pediatricians to recognize KD with neurological involvement and the importance of standard IVIG therapy.

TRIAL REGISTRATION

Retrospectively registered.

Identification of a novel anti‑heat shock cognate 71 kDa protein antibody in patients with Kawasaki disease

Kawasaki disease (KD) is an idiopathic form of acute systemic vasculitis, which clinically mimics febrile diseases. Although it has been hypothesized that immune system malfunction is associated with KD, its etiology remains unclear. The aim of the present study was to identify a KD‑associated antibody. Immunoproteomic methods were used to identify KD‑associated antigens that could be recognized in the sera of patients with KD. HeLa cells were used as an antigen source and KD sera were used as probe antibodies to determine the binding of the antibodies using an indirect immunofluorescence assay. Western blotting was performed to identify KD‑associated antigens in HeLa whole cell lysates. Eight out of 12 serum samples obtained from patients with KD demonstrated immunoreactive bands at ~70 kDa, which was later determined to be heat shock cognate 71 kDa protein (HSP7C) by mass spectrometry. The diagnostic value of serum anti‑HSP7C antibodies for KD was assessed using ELISA. Using a cut‑off value of 0.267, anti‑HSP7C antibodies were observed to be present in the sera of 60.00% (30/50) of patients with KD, in 21.05% (8/38) of non‑KD febrile controls, and in 5.26% (2/38) of healthy controls. High serum levels of anti‑HSP7C antibodies were detected in the peripheral circulation of patients with KD. To the best of our knowledge, the present study is the first to observe the high expression levels of anti‑HSP7C antibodies in patients with KD. Therefore, anti‑HSP7C antibodies may be used as a diagnostic marker to detect KD.

Interleukin-1 Beta-Mediated Sex Differences in Kawasaki Disease Vasculitis Development and Response to Treatment

OBJECTIVE

Kawasaki disease (KD) is the leading cause of acute vasculitis and acquired heart disease in children in developed countries. Notably, KD is more prevalent in males than females. We previously established a key role for IL (interleukin)-1 signaling in KD pathogenesis, but whether this pathway underlies the sex-based difference in susceptibility is unknown. Approach and Results: The role of IL-1 signaling was investigated in the Lactobacillus casei cell wall extract-induced experimental mouse model of KD vasculitis. Five-week-old male and female mice were injected intraperitoneally with PBS, Lactobacillus caseicell wall extract, or a combination of Lactobacillus caseicell wall extract and the IL-1 receptor antagonist Anakinra. Aortitis, coronary arteritis inflammation score and abdominal aorta dilatation, and aneurysm development were assessed. mRNA-seq (messenger RNA sequencing) analysis was performed on abdominal aorta tissue. Publicly available human transcriptomics data from patients with KD was analyzed to identify sex differences and disease-associated genes. Male mice displayed enhanced aortitis and coronary arteritis as well as increased incidence and severity of abdominal aorta dilatation and aneurysm, recapitulating the increased incidence in males that is observed in human KD. Gene expression data from patients with KD and abdominal aorta tissue of Lactobacillus caseicell wall extract-injected mice showed enhanced Il1b expression and IL-1 signaling genes in males. Although the more severe IL-1β-mediated disease phenotype observed in male mice was ameliorated by Anakinra treatment, the milder disease phenotype in female mice failed to respond.

CONCLUSIONS

IL-1β may play a central role in mediating sex-based differences in KD, with important implications for the use of anti-IL-1β therapies to treat male and female patients with KD.

The differential equation model of pathogenesis of Kawasaki disease with theoretical analysis

Fever is a extremely common symptom in infants and young children. Due to the lowresistance of infants and young, long-term fever may cause damage to the child's body. Clinically,some children with long-term fever was eventually diagnosed with Kawasaki disease (KD). KD, anautoimmune disease, is a systemic vasculitis mainly affecting children younger than 5 years old. Dueto the delayed therapy and diagnosis, coronary artery abnormalities (CAAs) develop in children with KD, and leads to a high risk of acquired heart disease. Later, patients may have myocardial infarctionor even die a sudden death. Unfortunately, at present, the pathogenesis of KD remains unknownand KD lacks of specific and sensitive biomarkers, thus bringing difficulties to diagnosis and therapy.Therefore it is a highly focused topic to research on the mechanism of KD. Some scholars believethat KD is caused by the cross reaction of external infection and organ tissue composition, herebytriggering disorder of the immune system and producing a variety of cytokines. On the basis ofconsidering the cytokines such as vascular endothelial cells, inflammatory factors, adhesion factorsand chemokines, endothelial cell growth factors, put forward a kind of dynamic model of pathogenesisof KD by the theory of ordinary differential equation. It is found that the dynamic model can showcomplex dynamic behavior, such as the forward and backward bifurcation of the equilibria. This articlereveals the possible complexity of KD infection, and provides a theoretical references for the researchof pathogenic mechanism and clinical treatment of KD.

Efficacy of primary treatment with immunoglobulin plus ciclosporin for prevention of coronary artery abnormalities in patients with Kawasaki disease predicted to be at increased risk of non-response to intravenous immunoglobulin (KAICA): a randomised controlled, open-label, blinded-endpoints, phase 3 trial

BACKGROUND

Genetic studies have indicated possible involvement of the upregulated calcium-nuclear factor of activated T cells pathway in the pathogenesis of Kawasaki disease. We aimed to assess safety and efficacy of ciclosporin, an immunosuppressant targeting this pathway, for protection of patients with Kawasaki disease against coronary artery abnormalities.

METHODS

We did a randomised, open-label, blinded endpoints trial involving 22 hospitals in Japan between May 29, 2014, and Dec 27, 2016. Eligible patients predicted to be at higher risk for intravenous immunoglobulin (IVIG) resistance were randomly assigned to IVIG plus ciclosporin (5 mg/kg per day for 5 days; study treatment) or IVIG (conventional treatment) groups, stratified by risk score, age, and sex. The primary endpoint was incidence of coronary artery abnormalities using Japanese criteria during the 12-week trial, assessed in participants who received at least one dose of study drug and who visited the study institution at least once during treatment. This trial is registered to Center for Clinical Trials, Japan Medical Association, number JMA-IIA00174.

FINDINGS

We enrolled 175 participants. One patient withdrew consent after enrolment and was excluded and one patient (in the study treatment group) was excluded from analysis because of lost echocardiography data. Incidence of coronary artery abnormalities was lower in the study treatment group than in the conventional treatment group (12 [14%] of 86 patients vs 27 [31%] of 87 patients; risk ratio 0·46; 95% CI 0·25-0·86; p=0·010). No difference was found in the incidence of adverse events between the groups (9% vs 7%; p=0·78).

INTERPRETATION

Combined primary therapy with IVIG and ciclosporin was safe and effective for favourable coronary artery outcomes in Kawasaki disease patients who were predicted to be unresponsive to IVIG.

FUNDING

Japan Agency for Medical Research and Development (grant CCT-B-2503).

[Research advances in the pathogenesis of familial Kawasaki disease]

Kawasaki disease has become the leading cause of acquired heart disease in children in North America and Japan. The incidence rate of Kawasaki disease varies significantly across regions and races. The first-degree relatives of patients with Kawasaki disease have a significantly higher risk of this disease than the general population. This article reviews the onset of familial Kawasaki disease and possible pathogenesis.

Innate immune responses following Kawasaki disease and toxic shock syndrome

The pathogenesis of Kawasaki disease (KD) remains unknown and there is accumulating evidence for the importance of the innate immune system in initiating and mediating the host inflammatory response. We compared innate immune responses in KD and toxic shock syndrome (TSS) participants more than two years after their acute illness with control participants to investigate differences in their immune phenotype. Toxic shock syndrome shares many clinical features with KD; by including both disease groups we endeavoured to explore changes in innate immune responses following acute inflammatory illnesses more broadly. We measured the in vitro production of interferon (IFN)-γ, tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-1 receptor antagonist (IL-1ra), and IL-10 following whole blood stimulation with toll-like receptor and inflammasome ligands in 52 KD, 20 TSS, and 53 control participants in a case-control study. Analyses were adjusted for age, sex, and unstimulated cytokine concentrations. Compared to controls, KD participants have reduced IL-1ra production in response to stimulation with double stranded RNA (geometric mean ratio (GMR) 0.37, 95% CI 0.15, 0.89, p = 0.03) and increased IL-6 production in response to incubation with Lyovec™ (GMR 5.48, 95% CI 1.77, 16.98, p = 0.004). Compared to controls, TSS participants have increased IFN-γ production in response to peptidoglycan (GMR 4.07, 95% CI 1.82, 9.11, p = 0.001), increased IL-1β production to lipopolysaccharide (GMR 1.64, 95% CI 1.13, 2.38, p = 0.01) and peptidoglycan (GMR 1.61, 95% CI 1.11, 2.33, p = 0.01), and increased IL-6 production to peptidoglycan (GMR 1.45, 95% CI 1.10, 1.92, p = 0.01). Years following the acute illness, individuals with previous KD or TSS exhibit a pro-inflammatory innate immune phenotype suggesting a possible underlying immunological susceptibility or innate immune memory.

The possible link between coeliac and Kawasaki diseases in Brazil: a cross-sectional study

BACKGROUND

Kawasaki disease (KD) is a self-limited acute systemic vasculitis of unknown aetiology that predominantly affects infants and young children eventually associated with immunological abnormalities. Coeliac disease (CD) is an inflammatory autoimmune disease characterised by a permanent gluten intolerance, which affects genetically susceptible individuals of any age group, and can cause intestinal and systemic symptoms. Association of CD with KD has been previously described in a single study that disclosed a surprisingly high prevalence of CD in children with a history of KD.

OBJECTIVE

To confirm the existence of a higher prevalence of CD among individuals with a history of KD, which would turn the screening for CD in patients with history of KD highly advisable.

SETTING

Children with history of KD, diagnosed and followed at the Rheumatology Clinic of the Children's Hospital of Brasilia (Brasilia, Brazil).

PARTICIPANTS

This study included 110 children with history of KD and a control group composed of 110 presumably healthy children.

INTERVENTIONS

Participants underwent anti-transglutaminase and anti-endomysial antibodies tests and genetic typing for the presence of CD predisposing alleles (HLA-DQ2 and DQ8). Jejunal biopsy was performed when necessary, according the European Society of Paediatric Gastroenterology, Hepatology and Nutrition guidelines.

RESULTS

Diagnosis of CD was confirmed in one (0.91%) patient with KD by positive serological tests, presence of predisposing alleles and CD typical lesions on duodenal biopsy. All serological tests were negative among the controls. The prevalence of CD predisposing alleles among patients with KD was 29.09%, similar to the prevalence found among controls, 33.64%.

CONCLUSION

The detected CD prevalence (0.91%) does not confirm the existence of an association between KD and CD since this prevalence is similar to that found in the general population (≃1%).

FCN1 (M-ficolin), which directly associates with immunoglobulin G1, is a molecular target of intravenous immunoglobulin therapy for Kawasaki disease

Kawasaki disease (KD), an acute systemic vasculitis of early childhood, is of unknown etiology. High-dose intravenous immunoglobulin (IVIG) is an effective treatment, but its molecular target remains elusive. DNA microarray analysis of peripheral blood mononuclear cells (PBMCs) revealed that at least 21 genes are drastically down-regulated after IVIG treatment in most KD patients. qRT-PCR analysis confirmed that the mRNA levels of five of these genes were considerably reduced in almost all KD patients after IVIG treatment. Western blot (Wb) of PBMC extracts revealed that levels of FCN1 (M-ficolin), a protein of the complement system that defends against infectious agents, were reduced after IVIG treatment in many KD patients. In another set of KD patients, Wb confirmed that levels of both FCN1 were greatly reduced after IVIG therapy. Wb revealed that the collagen-like domain of FCN1 directly bound to IgG1 in vitro through a portion of the CH1 and CH3 domains, and synthetic peptides corresponding to these domains of IgG1 efficiently inhibited these associations. These results suggest that FCN1 is a molecular target of intravenous IVIG in KD patients. We propose that these peptides and a humanized monoclonal antibody against FCN1 could be useful in combination therapy with IVIG.

Allograft Inflammatory Factor-1 Links T-Cell Activation, Interferon Response, and Macrophage Activation in Chronic Kawasaki Disease Arteritis

BACKGROUND

Kawasaki disease (KD) is widely viewed as an acute arteritis. However, our pathologic studies show that chronic coronary arteritis can persist long after disease onset and is closely linked with arterial stenosis. Transcriptome profiling of acute KD arteritis tissues revealed upregulation of T lymphocyte, type I interferon, and allograft inflammatory factor-1 (AIF1) genes. We determined whether these immune responses persist in chronic KD arteritis, and we investigated the role of AIF1 in these responses.

METHODS

Gene expression in chronic KD and childhood control arteries was determined by real-time reverse-transcriptase polymerase chain reaction, and arterial protein expression was determined by immunohistochemistry and immunofluorescence. Allograft inflammatory factor-1 small-interfering ribonucleic acid macrophage treatment was performed to investigate the role of AIF1 in macrophage and T lymphocyte activation.

RESULTS

Allograft inflammatory factor-1 protein was highly expressed in stenotic KD arteries and colocalized with the macrophage marker CD68. T lymphocyte and interferon pathway genes were significantly upregulated in chronic KD coronary artery tissues. Alpha interferon-induced macrophage expression of CD80 and major histocompatibility complex class II was dependent on AIF1, and macrophage expression of AIF1 was required for antigen-specific T lymphocyte activation.

CONCLUSIONS

Allograft inflammatory factor-1, originally identified in posttransplant arterial stenosis, is markedly upregulated in KD stenotic arterial tissues. T lymphocyte and type I interferon responses persist in chronic KD arteritis. Allograft inflammatory factor-1 may play multiple roles linking type I interferon response, macrophage activation, and antigen-specific T lymphocyte activation. These results suggest the likely importance of lymphocyte-myeloid cell cross-talk in the pathogenesis of KD arteritis and can inform selection of new immunotherapies for clinical trials in high-risk KD children.

1,25-Dihydroxyvitamin D3 regulates T lymphocyte proliferation through activation of P53 and inhibition of ERK1/2 signaling pathway in children with Kawasaki disease

OBJECTIVE

To study the effect of 1,25(OH)2D3 on T lymphocytes in Kawasaki disease and to further investigate its molecular mechanism.

PATIENTS AND METHODS

A total of 30 child patients was diagnosed as Kawasaki disease, 60 child patients were diagnosed as infectious fever, and 60 normal children, were selected. 4 mL peripheral blood was collected before treatment. Peripheral blood mononuclear cells were isolated and separated using the Facollin method and cultured. Flow cytometry was used to identify T cells. The cell sections were prepared for immunohistochemical staining. After T cells in each group were treated with 1,25(OH)2D3, the proteins were extracted for Western blotting.

RESULTS

Peripheral blood T cells were successfully isolated and cultured, and the maximal atoxic concentration of 1,25(OH)2D3 on T cells was 10-3 μmol/L. In T cells of child patients with Kawasaki disease, signal transducer and activator of transcription 3 (STAT3) were continuously activated, P53 apoptosis genes were inactivated, and nuclear factor κB (NF-κB) P65 pathway and extracellular signal-regulated kinase (ERK) pathway were activated. After the intervention with 1,25(OH)2D3 in vitro, STAT3 and NF-κB P65 had no significant changes, the activation of ERK1/2 signaling pathway was inhibited and the P53 protein was activated.

CONCLUSIONS

Apoptotic T cells in peripheral blood in KD cannot initiate the normal apoptosis program, so they continue to proliferate and differentiate, eventually leading to the increase and abnormal activation of T cells and the immune imbalance in the body. 1,25(OH)2D3 can inhibit the excess hyperplasia of T cells through adjusting partial signal transduction pathway.

Correlation between elevated platelet count and immunoglobulin levels in the early convalescent stage of Kawasaki disease

Kawasaki disease (KD) may be an acute systemic immune-mediated disease which occurs after infection of unknown KD pathogen(s). The aim of this study is to evaluate the changes in platelet count and immunoglobulin (Ig) levels (IgG, IgM, IgA, and IgE) during hospitalization.Forty-three patients with complete KD who received intravenous Ig at 2 g/kg were enrolled in South Korea. The platelet count and Ig levels of the patients were examined twice at presentation and around discharge (mean 6.2 ± 2.4 days apart) and the relationships between platelet level and Ig levels were evaluated.The mean patient age was 31 ± 18 months; 28 patients were male and 15 were female. The values of all parameters measured, with the exception of IgE, were significantly increased at the second examination compared with their values at presentation. These values gradually increased over time after fever onset, over periods ranging from 2 to 16 days. The extent by which platelet levels increased over these 2 time points was correlated with the extents by which IgG (P < .01), IgM (P < .01), and IgA levels (P = .01) increased.Both the platelet count and the Ig (IgG, IgM, and IgA) levels increased with a correlation each other during the early convalescent stage of KD. This finding suggests that all Ig subtypes except IgE and platelets may be involved in the recovery from KD and that the extent of increased parameters may reflect the degree of systemic inflammation in acute KD.

High-dose aspirin for Kawasaki disease: outdated myth or effective aid?

OBJECTIVES

To compare the efficacy and safety of intravenous immunoglobulin (IVIG) plus high-dose aspirin (HDA) vs. IVIG plus low-dose aspirin (LDA) for the treatment of Kawasaki disease, with an emphasis on coronary artery outcomes.

METHODS

This study was a retrospective, medical record review of paediatric patients with Kawasaki disease comparing 6 centres that routinely used HAD for initial treatment and 2 that used LDA in 2004-2013. Treatment response and adverse events were compared. The primary outcome measure was the occurrence of coronary aneurysm at the subacute or convalescent stage.

RESULTS

The cohort included 358 patients, of whom 315 were initially treated with adjunctive HDA and 43 with LDA. There were no demographic differences between the groups. Coronary aneurysms occurred in 10% (20/196) of the HDA group and 4% (1/24) of the LDA group (p=0.34). Equivalence tests indicate it is unlikely that the risk of coronary aneurysm in LDA exceeds HDA by more than 3.5%. There were no significant between-group differences in the need for glucocorticoid pulse therapy or disease recurrence. Coronary ectasia rate and hospitalisation time were significantly greater in the HDA group. Adverse events were similar in the two groups.

CONCLUSIONS

We found no significant clinical benefit in using IVIG+HDA in Kawasaki disease compared to IVIG+LDA. The use of adjunctive HDA in this setting should be reconsidered.

[Changes in peripheral blood T helper 9 cells and interleukin-9 in children in the acute stage of Kawasaki disease]

OBJECTIVE

To investigate the changes in the expression levels of peripheral blood T helper 9 (Th9) cells and cytokine interleukin-9 (IL-9) in children in the acute stage of Kawasaki disease (KD) and their clinical significance.

METHODS

A total of 45 children in the acute stage of KD who were treated from April 2014 to July 2015 were enrolled, and the children were followed up in the recovery stage. Another 45 healthy children who underwent physical examination were enrolled as the control group. Flow cytometry was used to measure the percentage of peripheral blood Th9 cells, and ELISA was used to measure the serum level of IL-9.

RESULTS

The children in the acute stage of KD showed a significantly higher percentage of Th9 cells and a significantly higher serum level of IL-9 compared with those in the recovery stage and the control group (P<0.05). The percentage of Th9 cells and serum level of IL-9 showed no significant differences between the children in the recovery stage and those in the control group (P>0.05). In the acute stage, the percentage of Th9 cells was positively correlated with the levels of IL-9, C-reactive protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate (ESR), platelet count (PLT), and globulin (r=0.624, 0.324, 0.402, 0.382, 0.467, and 0.386 respectively, all P<0.05), but negatively correlated with serum albumin (r=-0.306, P<0.05). The serum level of IL-9 was positively correlated with the levels of CRP, PCT, ESR, PLT, and globulin (r=0.365, 0.456, 0.403, 0.423, and 0.453 respectively, all P<0.05), but negatively correlated with serum albumin (r=-0.343, P<0.05).

CONCLUSIONS

The children in the acute stage of KD show significant increases in the percentage of peripheral Th9 cells and serum cytokine IL-9 level, which return to normal in the recovery stage. In the acute stage of KD, the expression levels of Th9 and IL-9 are closely correlated with laboratory markers. The results suggest that Th9 cells and IL-9 play important roles in the pathogenesis and outcome of KD.

[Role of triggering receptor expressed on myeloid cells-1 in the pathogenesis of Kawasaki disease]

OBJECTIVE

To study the role of triggering receptor expressed on myeloid cells-1(TREM-1) in the pathogenesis of Kawasaki disease (KD).

METHODS

Based on color Doppler examination results, 45 children with KD were classified into two groups: coronary artery lesions (CAL group) and no coronary artery lesions (NCAL group). Fifteen children with fever caused by respiratory infection (fever control group) and fifteen healthy children (normal control group) served as controls. Real-time fluorescence quantitative PCR was used to detect the expression of TREM-1 mRNA and DNAX-activating protein 12 (DAP12) mRNA in peripheral blood mononuclear cells (PBMC). ELISA was used to detect the expression of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), DAP12, monocyte chemoattractant protein-1(MCP-1), interleukin-8 (IL-8) proteins levels.

RESULTS

The mean serum protein concentrations of sTREM-1 and DAP12 and the expression levels of TREM-1 mRNA and DAP12 mRNA in PBMC in 45 children with KD (KD group) were significantly higher than in the two control groups (P<0.05). The levels of sTREM-1 protein and TREM-1 mRNA in the CAL subgroup were significantly higher than in the NCAL subgroup (P<0.05). The serum protein concentrations of MCP-1 and IL-8 in the KD group were significantly higher than in the two control groups (P<0.05). The MCP-1 protein level in the CAL subgroup was significantly higher than in the NCAL subgroup (P<0.05). In children with KD, there was a positive correlation between serum sTREM-1 and MCP-1 levels (r=0.523, P<0.05).

CONCLUSIONS

TREM-1 activation may be involved in the development of KD.

Interferon-gamma Genetic Polymorphism and Expression in Kawasaki Disease

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology. IFNG gene encoding interferon (IFN)-γ, produced by natural killer cells and T cells, has been suggested to play an important role in the immunopathogenesis of Kawasaki disease. The aim of this study was to examin the correlation of gene polymorphisms of the IFNG gene and plasma levels of IFN-γ in KD patients and their outcomes.A total of 950 subjects (381 KD and 569 controls) were recruited. Three tagging single-nucleotide polymorphisms (rs2069718, rs1861493, rs2069705) were selected for TaqMan allelic discrimination assay. Clinical phenotypes, coronary artery lesions (CAL), coronary artery aneurysms (CAA) and intravenous immunoglobulin (IVIG) treatment outcomes were collected for analysis. Plasma IFN-γ levels were also measured with an enzyme-linked immunosorbent assay.Polymorphisms of the IFNG gene were significantly different between the normal controls and KD patients. The G allele of rs1861493 conferred a better response to IVIG treatment in KD patients. AA allele frequencies of rs1861493 were also associated with a significantly higher risk of CAA in KD patients. Furthermore, the plasma IFN-γ level was lower in the AA allele than in the GG allele of rs1861493 both before and after IVIG treatment in KD patients.This study provides the first evidence supporting an association between IFNG gene polymorphisms, susceptibility of KD, IVIG responsiveness, and plasma IFN-γ levels in KD patients.

[Up-regulation of serum- and glucocorticoid-inducible kinase 1 (SGK1) of CD4⁺ T cells is positively related to RORC and IL-17A in patients with Kawasaki disease]

OBJECTIVE

To investigate the expression of serum- and glucocorticoid-inducible kinase 1 (SGK1) in Kawasaki disease (KD) and explore the correlations between SGK1 and Th17 cell-related cytokines [retinoic-acid-related orphan nuclear receptor C (RORC), interleukin 17A (IL-17A), IL-6] in KD.

METHODS

Thirty patients with KD [(2.8 ± 1.4) years old], 30 healthy volunteers [(2.6 ± 1.6) years old] and 25 patients with infectious disease (ID) [(2.2 ± 1.5) years old] were recruited. The percentage of Th17 cells in CD4⁺ T cells was analyzed using flow cytometry. The mRNA levels of RORC and SGK1 in CD4⁺ T cells were detected using real-time quantitative PCR. The serum levels of IL-17A and IL-6 were analyzed by ELISA.

RESULTS

Compared with healthy volunteers and patients with ID, the percentage of Th17 cells in CD4⁺ T cells significantly increased in KD [(3.57 ± 0.62)% vs (0.51 ± 0.07)% or (1.72 ± 0.36)%]. The serum levels of IL-17A and IL-6 in KD were much higher than those in healthy volunteers and patients with ID. The mRNA levels of RORC and SGK1 in KD were remarkably elevated compared with healthy volunteers and patients with ID. The level of SGK1 in coronary artery lesion (CAL) group of KD was significantly higher than that in KD patients with normal coronary artery (CAN). SGK1 was reduced in KD after intravenous immunoglobulin (IVIG) treatment. What's more, the decrease of SGK1 was more obviously in the CAL group than in the CAN group. In addition, SGK1 expression in KD was positively correlated with RORC and IL-17A, but not with IL-6.

CONCLUSION

SGK1 was up-regulated in CD4⁺ T cells and was positively correlated with RORC and IL-17A in the patients with KD.

Identification of 4-Trimethylaminobutyraldehyde Dehydrogenase (TMABA-DH) as a Candidate Serum Autoantibody Target for Kawasaki Disease

Kawasaki disease (KD), an acute vasculitis that preferentially affects coronary arteries, is still the leading cause of acquired heart disease in children. Although the involvement of immune system malfunction in the onset of KD is suggested, its etiology still remains to be clarified. We investigated autoantibodies in KD patients, which are frequently found in sera from patients with autoimmune diseases, vasculitides and arteritides. We performed two-dimensional western blotting and LC-MS/MS to analyze the antigens of autoantibodies, detected two protein spots with 4 out of 24 sera from KD patients but not with 6 control sera, and identified the antigens as 4-trimethylaminobutyraldehyde dehydrogenase (TMABA-DH). A slot blot analysis with TMABA-DH as an antigen also revealed higher reactivities of patients' sera than control sera (positive rates: 18/43 vs 3/41). Using an enzyme-linked immunosorbent assay (ELISA), we found that the reactivity of anti-TMABA-DH antibodies in sera from KD patients was significantly higher than that in sera from age-matched controls. The optimal cut-off value of 0.043 had a sensitivity of 83.7% and a specificity of 80.0% in detecting KD patients (positive rates: 37/43 for KD patients, 9/41 for controls). Immunohistochemistry performed on thin sections of rat heart revealed that TMABA-DH colocalized with myosin light chains in cardiac myocytes. Patient sera with high reactivity gave similar immunostaining pattern. These results suggest that the detection of anti-TMABA-DH autoantibody could be a potential strategy for a diagnosis of KD.

[Immunoglobulin therapy]

Kawasaki disease(KD) is an acute, self-limited vasculitis of unknown etiology that predominantly affects infants and children. Coronary artery(CA) aneurysms, the most severe complication, occur in 25 % of untreated children and may lead to ischemic heart disease, myocardial infarction, or sudden death. While a single high dose of intravenous immunoglobulin (IVIG) terminates the fever and acute inflammation in most subjects and dramatically reduces the incidence of CA aneurysms, 10 to 20 % of KD patients are IVIG- resistant and these subjects are at higher risk of developing CA abnormalities. Several mechanisms have been reported for the anti-inflammatory activity of IVIG in different disease states. In this review, we describe the clinical utility and these mechanisms of IVIG in KD.

[Present situation and new challenges for medical treatment of Kawasaki disease]

To predict resistance to intravenous immunoglobulin (MIG) treatment in patients with severe Kawasaki disease (KD), Gunma, Kurume, and Osaka risk scores were established. Using these scores, prospective randomised trials were performed, and addition of predni- solone or intravenous methylprednisolone -pulse to the standard regimen of IVIG improves coronary artery outcomes in severe KD. Adding the evidences of new and existing therapies, such as infliximab, cyclosporin A, ulinastatin, and plasma exchange, the clinical guideline for medical treatment of the acute phase of KD was revised in 2012. Additional large cohort studies are needed to clarify the applicability of intensive initial treatment. Challenges for the future are: 1) clarification of etiology and establishment of specific therapy, 2) establishment of personalized therapy using genetic markers related to the severity of KD.

[Cyclosporin A treatment for refractory Kawasaki disease]

The association between functional polymorphism of inositol 1,4,5-trisphosphate 3- kinase-C(ITPKC) and susceptibility to Kawasaki disease(KD) and formation of coronary arterial lesions was reported in 2008. Since ITPKC acts as a negative regulator of T-cell activation, activated T cells may play a pivotal role in the pathogenesis of KD. Cyclosporin A(CsA), which potently suppresses the activity of T cells through negative regulation of the nuclear factor of activated T cells(NFAT) pathway, may be a promising candidate for the treatment of refractory KD. In this review, we summarize the results of our clinical trials of CsA for refractory KD, the changes in the levels of cytokines before and after CsA treatment, and the future direction of CsA treatment for refractory KD.

[Anti TNF-α (infliximab) treatment for intravenous immunoglobulin (IVIG) resistance patients with acute Kawasaki disease the effects of anticytokine therapy]

Among the patients with acute Kawasaki disease treated with intravenous immunoglobulin (IVIG), 10-20 % demonstrate resistance or incomplete effects. Cardiac complication such as the coronary arterial aneurysm is frequent in these patients. For patients with IVIG-resistance, we have surveyed the efficacy and safety of anti-cytokine therapy with use of infliximab (Remicade), chimera type anti TNF-α agent, for children. After May, 2005, Remicade has been used in >500 pediatric patients in whom IVIG and intravenous methylprednisolone pulse therapy did not show significant effects. The efficacy and safety of Remicade on patients with IVIG-resistant Kawasaki disease has been observed but 10~20 % of patients was Remicade-resistant. Re-treatment with IVIG or steroids was also effective. The efficacy of Remicade for reducing the fever duration, CRP, WBC counts was promising, but reduction of the incidence of coronary aneurysm was not confirmed. Randomized clinical trial will be needed.

[Kawasaki disease and innate immunity]

Kawasaki disease (KD) is an acute self-limited systemic vasculitis, and could develop in association with innate immune disorders. An innate immune system appears to play a key role in the development of KD, because pathogen-associated molecular patterns(PAMPs) and damage-associated molecular patterns(DAMPs) are elevated in the sera at acute phase KD, and oral administration of innate immune Nod1 ligand induces KD-like coronary arteritis in mice. PAMPs can be produced massively from microbes in a certain condition. DAMPs are produced from the host cells by the stimulation of PAMPs. We propose a hypothesis that PAMPs and DAMPs activate innate immune system and vascular cells through innate immune pattern recognition receptors(PRR) to release chemokines and cytokines, and induce KD in genetically predisposed individuals.

[Cytokines in Kawasaki disease]

We analyzed plasma levels of 14 cytokines in patients with Kawasaki disease (KD) before intravenous infusion of immunoglobulin (WIG) therapy using multiplex bead assay system. The results demonstrated that both inflammatory(TNF-α, IL-6, IL-8, IL-17, IFN-γ, G-CSF, MCP-1 and sIL-2Rα) and anti-inflammatory(IL-10, sTNFR1 and sTNFR2) cytokine levels were simultaneously elevated in patients refractory to the initial IVIG therapy. System-level understanding of the cytokine networks would be the key to develop a new therapeutic strategy to prevent coronary artery injuries in KD.

Expression of CD11b as an adhesion molecule on neutrophils in children with Kawasaki disease

Inflammation of blood vessels is a characteristic feature of Kawasaki disease. Neutrophils play a key role in the inflammatory responses where movement of neutrophils toward the site of inflammation depends on CD11b/CD18 expression as adhesion molecules on these cells. The purpose of this study was to investigate CD11b/CD18 expression in patients with Kawasaki disease upon diagnosis and after treatment.The study included 20 children with Kawasaki disease aged from 3 months to 8 years. Mean fluorescence intensity of CD11b levels on diagnosis and at 1-2 and 6 weeks after intravenous immunoglobulin (IVIG) therapy was measured in these patients. Level of CD11b was measured in age-matched healthy children and febrile children (each 21) as negative and positive controls, respectively.Mean fluorescence intensity of CD11b in Kawasaki patients was lower than that of the control groups before and after 1-2 weeks of IVIG therapy. There were no significant differences in CD11b in Kawasaki patients either with aneurysm or without aneurysm. The CD11b levels at the diagnosis time and after treatment with IVIG in our patients with Kawasaki were lower than the control groups.

[Clinical significance of anti-neutrophil cytoplasmic antibodies and anti-endothelial cell antibodies in children with Kawasaki disease]

OBJECTIVE

To study the clinical significance of anti-endothelial cell antibodies (AECA) and anti-neutrophil cytoplasmic antibodies (ANCA) in Kawasaki disease (KD) and its complication of coronary arterial lesions (CAL).

METHODS

Forty-two children with KD, as well as 20 children with fever caused by respiratory infection (fever control group) and 15 children for selective operation (normal control group), were included in the study. Serum levels of AECA and ANCA were measured using enzyme-linked immunosorbent assay. Echocardiography was performed to evaluate CAL in KD patients.

RESULTS

During the acute phase, the KD patients had significantly higher serum AECA and ANCA levels than the two control groups (P<0.01). The KD patients had reduced serum ANCA levels (P<0.01) in the remission phase, but they were still higher than those of the two control groups (P<0.05). Among KD patients, those with CAL had significantly higher ANCA levels than those without CAL (P<0.01) in the acute phase. There was a positive correlation between serum ANCA levels and the ratio of left coronary artery to aortic annular diameter in KD patients with CAL (r=0.88, P<0.01).

CONCLUSIONS

AECA and ANCA may be involved in vasculitis and CAL among children with KD. Serum levels of AECA and ANCA may be used as indicators for the diagnosis of suspected KD cases in the acute phase. Elevated ANCA level has a certain predictive value for CAL.

The role of the inflammasome in cardiovascular diseases

Inflammasome is a very important signaling platform sensing a variety of triggers of the innate immune system. Inflammasome promotes the production of important pro-inflammatory cytokines such as IL-1β and IL-18. Tight control of inflammasome activity is, therefore, essential and occurs at multiple levels. The activation of inflammasome pathways is linked to the pathogenesis of various prevalent disorders including cardiovascular disease such as atherosclerosis, ischemic injury, cardiomyopathy, and Kawasaki disease. The study of the inflammasome in the cardiovascular system has led to the identification of important triggers and endogenous modulators, and to the exploration of new treatment strategies based on the inhibition of inflammasome activation or its end products, i.e., IL-1β and IL-18. In summary, the discovery of the inflammasome has greatly advanced our understanding of how the innate immune system interferes with cardiovascular disease development and progression, and targeting inflammasome provides new avenues for the treatment and management of cardiovascular diseases.

Serological Identification of Endothelial Antigens Predominantly Recognized in Kawasaki Disease Patients by Recombinant Expression Cloning

We showed IgG immune response against endothelial antigens in sera obtained from convalescent Kawasaki disease (KD) patients after recovery from the disease during the follow-up period using serological analysis of recombinant cDNA expression library (SEREX) methodology. We identified 46 antigens represented by 69 clones by immunoscreening of a cDNA expression library from tumor necrosis factor-alpha (TNFalpha) treated human umbilical vein endothelial cells (HUVEC) with sera from 4 KD patients. They included ubiquitin pathway proteins, transcriptional factors, signal transduction molecules, metabolic enzymes, cytoskeletal proteins, an adhesion molecule, and a cell cycle protein. By serological survey using phage plaque assay, sera from 5 non-KD patients were rarely reactive with the antigens. Among the antigens, tropomyosin was most frequently isolated (18 of 69 clones). Seventeen of the 18 clones were identified using KD3 serum. The second most frequently isolated antigen was also a cytoskeletal protein, called Tplastin (3 of 69 clones).

Interleukin-18 and coronary artery lesions in patients with Kawasaki disease

BACKGROUND

Interleukin-18 (IL-18) plays an important role in mediating cytokine cascade leading to coronary artery lesions (CALs) in Kawasaki disease (KD). However, our research suggested that the literature regarding IL-18 and KD is limited. Consequently, this study aimed to evaluate the correlation between IL-18 and CALs in patients with KD.

METHODS

In this prospective study of 14 children with KD (seven without and seven with CALs in the acute phase), we obtained patient measurements of a series of serum IL-18 levels in the acute, subacute, and convalescent phases. Serum IL-18 levels were measured with a Bio-Plex cytokine assay. Control samples were obtained from 18 febrile children with viral infection.

RESULTS

Compared with febrile controls, patients with acute-stage CALs [postintravenous immunoglobulin (post-IVIG) period] had a significantly higher IL-18 level (88.4 ± 20.7 vs 56.0 ± 35.0 pg/mL, p = 0.006). However, those without acute-stage CALs (post-IVIG period) lacked similarly elevated IL-18 level readings (62.0 ± 40.6 vs 56.0 ± 35.0 pg/mL, p = 0.762). The IL-18 level of patients with acute-stage CALs did not decrease significantly until the convalescent phase (97.4 ± 55.8 vs 38.7 ± 22.6 pg/mL, p = 0.018), but for those without CALs, it decreased significantly in the subacute phase (60.2 ± 37.4 vs 23.6 ± 13.8 pg/mL, p = 0.018). In the subacute stage, there was a significant difference of IL-18 level between patients with and without acute-stage CALs (p = 0.048).

CONCLUSION

Our data show that IL-18 levels were elevated in the acute phase of KD and might be related to the formation of CALs.

Kawasaki disease and soy: potential role for isoflavone interaction with Fcγ receptors

Kawasaki disease (KD) is a diffuse vasculitis occurring in children and showing predilection for the coronary arteries. The etiology remains unknown, although some risk factors for susceptibility have been defined. Asian ethnicity is a primary risk factor. Several theories have circulated regarding the differences in KD ethnic incidence. Those theories implicating genetic differences among populations as the cause for this discrepancy have dominated and are areas of active investigation by multiple research groups. Differences in diet between Asians and Westerners are touted as reasons for certain ethnic-related discrepancies in susceptibility to cardiovascular disease and cancer in adults. Surprisingly, these cultural dietary differences have not been previously considered as the source of the discrepancy in KD incidence among these ethnic populations. Recent data from genetic studies have highlighted the role of specific immune receptors in the pathogenesis of KD. Functions of the Fcγ receptors (FcGRs) are modulated by isoflavones in soy, in particular, genistein. Epidemiological data from Hawaiian populations support an association between soy consumption and KD. These observations form the basis of a hypothesis: isoflavones participate in KD pathogenesis by modulating function of the FcGRs and by disrupting the balance between activation and inhibition of the inflammatory response.

Kawasaki syndrome and concurrent Coxsackie virus B3 infection

We describe two previously healthy children who were hospitalized in the same period in different departments of our University with clinical signs of Kawasaki syndrome, which were treated with intravenous immunoglobulins and acetylsalicylic acid: in both cases, Coxsackie virus infection was concurrently demonstrated by enzyme-linked immunosorbent assay, and complement fixation test identified antibodies to serotype B3. In the acute phase, both patients presented hyperechogenic coronary arteries, but no cardiologic sequels in the mid term. The etiological relationship between Kawasaki syndrome and Coxsackie viruses is only hypothetical; however, the eventual identification of ad hoc environmental triggers is advisable in front of children with Kawasaki syndrome, with the aim of optimizing epidemiological surveillance and understanding the intimate biological events of this condition.