Humoral cross-coronavirus responses against the S2 region in children with Kawasaki disease.

Multisystem Inflammatory Syndrome in Children (MIS-C), a post infectious complication of SARS CoV-2 infection, shares enough features with Kawasaki Disease (KD) that some have hypothesized cross-coronavirus (CoV) immunity may explain the shared pathology. Recent studies have shown that humoral cross-reactivity of the CoVs, particularly of OC43, is focused on the S2 region of the Spike protein. Due to efforts utilizing CoV S2 regions to produce a cross-CoV vaccine, we wished to assess SARS-CoV-2 S2 reactivity in children with KD and assess if cardiac involvement in KD correlated with S2 CoV antibody targeting. The presence of cross-reactivity does not distinguish KD from febrile controls and does not correlate with cardiac involvement in KD. These findings support that, in relation to cardiac vascular inflammation, vaccines targeting the S2 region appear to be a safe approach, but there is disparity in the ability of CoV species to raise cross-reactive S2 targeted antibodies.

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

WHAT IS KNOWN AND OBJECTIVE: An extensively documented multisystem inflammatory syndrome (MIS) has been observed in a small but significant percentage of COVID-19 patients, in some adults but primarily in paediatric patients, and for these patients it is sometimes called MIS-C. COMMENT: Kawasaki disease has also been observed over the last several decades in patients that tested positive for a variety of very virulent pathogens. Several differences and similarities between MIS-C and Kawasaki disease pathology have been observed. Several puzzling aspects of MIS-C, Kawasaki disease and other Kawasaki-like diseases have been discussed, but not yet explained. WHAT IS NEW AND CONCLUSION: An explanatory hypothesis has been presented. Using the hypothesis that a transient or permanent inability to quickly phagocytize antigen-antibody immune complexes created by a novel virulent pathogen infection induces a Type III hypersensitivity immune response and the resulting proteinase exposure and expression of new autoantigens are the fundamental steps for MIS and other Kawasaki-like diseases, it is possible to provide straightforward explanations for at least 10 of the most puzzling aspects of these diseases. The validity of the hypothesis itself is also supported by its ability to provide consistent and straightforward explanations for a large number of these disease aspects. Furthermore, these straightforward explanations and the explanatory hypothesis on which they are based also suggest several potential new treatments, which could possibly be more effective than various treatments in current use.

Multisystem Inflammatory Syndrome Following SARS-CoV-2 Infection in Children: One Year after the Onset of the Pandemic in a High-Incidence Area.

SARS-CoV-2 infection in children can trigger cardiovascular manifestations potentially requiring an intensive treatment and defining a new entity named Multisystem Inflammatory Syndrome in Children (MIS-C), whose features partially overlap with Kawasaki Disease (KD). A cross-sectional study including all diagnoses of MIS-C and KD from April 2020 to May 2021 in our metropolitan area was conducted evaluating clinical, laboratory (including immunological response, cytokines, and markers of myocardial damage), and cardiac (coronary and non-coronary) features at onset of the diseases. Evolution of ventricular dysfunction, valve regurgitations, and coronary lesions was documented. The severity of the disease was also considered based on the need for inotropic support and ICU admission. Twenty-four MIS-C were diagnosed (14 boys, median age 82 months): 13/24 cases (54.17%) presented left ventricular dysfunction, 12/24 (50%) required inotropic support, and 10/24 (41.67%) developed coronary anomalies (CALs). All patients received steroids and IVIG at a median time of 5 days (IQR1:4, IQR3:6.5) from onset of fever and heart function normalized 6 days (IQR1: 5, IQR3: 7) after therapy, while CALs persisted in one. One patient (12.5%) required infliximab because of refractory disease and still presented CALs 18 days after therapy. During the same study period, 15 KD were diagnosed: none had ventricular dysfunction, while 7/15 (46.67%) developed CALs. Three out of 15 patients (20%) still presented CALs 46 days from onset. Compared to KD, MIS-C pts have significantly higher IL8 and similar lymphocytes subpopulations. Despite a more severe presentation and initial cardiac findings compared to KD, the myocardial injury in MIS-C has a rapid response to immunomodulatory treatment (median time 6 days), in terms of ventricular function, valve regurgitations, and troponin. Incidence of CALs is similar at onset, but it tends to regress in most of the cases of MIS-C differently than in KD where CALs persist in up to 40% in the subacute stage after treatment.

Characterizing the differences between multisystem inflammatory syndrome in children and Kawasaki disease.

To characterize the new SARS-Co-V-2 related multisystem inflammatory syndrome in children (MIS-C) among Israeli children and to compare it with Kawasaki disease (KD). We compared, in two medical centers, the clinical and laboratory characteristics of MIS-C, KD and an intermediate group, which met the case definitions of both conditions. MIS-C patients were older, were more likely to be hypotensive, to have significant gastrointestinal symptoms, lymphopenia and thrombocytopenia and to have non-coronary abnormal findings in their echocardiogram. Lymphopenia was an independent predictor of MIS-C. Most of our MIS-C patients responded promptly to corticosteroid therapy. KD incidence in both centers was similar in 2019 and 2020. Although there is clinical overlap between KD and MIS-C, these are separate entities. Lymphopenia clearly differentiates between these entities. MIS-C patients may benefit from corticosteroids as first-line therapy.

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.

Multisystem inflammatory syndrome (MIS-C) in Pakistani children: A description of the phenotypes and comparison with historical cohorts of children with Kawasaki disease and myocarditis.

OBJECTIVES: To determine clinical, laboratory features and outcomes of Multisystem Inflammatory Syndrome in children (MIS-C) and its comparison with historic Kawasaki Disease (KD) and Viral Myocarditis (VM) cohorts. METHODS: All children (1 month- 18 years) who fulfilled the World Health Organization criteria of MIS-C presenting to two tertiary care centers in Karachi from May 2020 till August 31st were included. KD and VM admitted to one of the study centers in the last five years prior to this pandemic, was compared to MIS-C. RESULTS: Thirty children with median age of 24 (interquartile range (IQR)1-192) months met the criteria for MIS-C. Three phenotypes were identified, 12 patients (40%) with KD, ten (33%) VM and eight (26%) had features of TSS. Echocardiography showed coronary involvement in 10 (33%), and moderate to severe Left Ventricular dysfunction in 10 (33%) patients. Steroids and intravenous immunoglobulins (IVIG) were administered to 24 (80%) and 12 (41%) patients respectively while 7 (23%) received both. Overall, 20% children expired. During the last five years, 30 and 47 children were diagnosed with KD and VM, respectively. Their comparison with MIS-C group showed lymphopenia, thrombocytosis, and higher CRP as well as more frequent atypical presentation in MIS-C KD group with less coronary involvement. The MIS-C VM was more likely to present with fulminant myocarditis. CONCLUSIONS: Our MIS-C cohort is younger with higher mortality compared to previous reports. MIS-C is distinct from historic cohorts of KD and VM in both in clinical features and outcomes.

Cardiac pathology and outcomes vary between Kawasaki disease and PIMS-TS.

Overlapping clinical features promoted the discussion of whether Kawasaki disease (KD) and PIMS-TS share pathophysiological features and disease outcomes. Medical records from English patients with KD (2015-02/20, N = 27) and PIMS-TS (02/2020-21, N = 34) were accessed to extract information. Children with PIMS-TS were older and more frequently of minority ethnicity background. They patients more commonly exhibited cytopenias and hyperferritinemia, which associated with diffuse cardiac involvement and functional impairment. In some PIMS-TS cases, cardiac pathology developed late, but outcomes were more favorable. In both, KD and PIMS-TS, baseline coronary diameter was a predictor of outcomes. PIMS-TS treatment more frequently included respiratory and cardiovascular support, and corticosteroids with IVIG. Cardiac involvement in PIMS-TS may be the result of a cytokine storm. Though more severe and diffuse when compared to KD, cardiac involvement of PIMS-TS has a more favorable prognosis, which may, after recovery, mitigate the need for long-term follow up.

Chemical and Biochemical Aspects of Molecular Hydrogen in Treating Kawasaki Disease and COVID-19.

Kawasaki disease (KD) is a systemic vasculitis and is the most commonly acquired heart disease among children in many countries, which was first reported 50 years ago in Japan. The 2019 coronavirus disease (COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)) has been a pandemic in most of the world since 2020, and since late 2019 in China. Kawasaki-like disease caused by COVID-19 shares some symptoms with KD, referred to as multisystem inflammatory syndrome in children, and has been reported in the United States, Italy, France, England, and other areas of Europe, with an almost 6-10 times or more increase compared with previous years of KD prevalence. Hydrogen gas is a stable and efficient antioxidant, which has a positive effect on oxidative damage, inflammation, cell apoptosis, and abnormal blood vessel inflammation. This review reports the chemical and biochemical aspects of hydrogen gas inhalation in treating KD and COVID-19.

The wide spectrum of Kawasaki-like disease associated with SARS-CoV-2 infection.

Introduction: On June 2020, the first case of concurrent Covid-19 and Kawasaki disease (KD) was published. After this first description, further works reported new cases of children affected by KD and KD-like syndrome after SARS-CoV-2 infection. The clinical and biochemical features of these patients differed from the historical cohorts of KD, suggesting the possibility of a new multi-systemic inflammatory syndrome. Is still unclear if this new clinical entity, often referred as pediatric inflammatory multisystem syndrome (PIMS) or multi-system inflammatory syndrome in children (MIS-C), could be considered as part of the KD spectrum or is a new disease with different pathogenic mechanisms and uniquely linked to SARS-CoV-2 infection. The authors searched the available literature in MedLine (via Pubmed) with the terms ('coronaviruses' OR 'coronavirus') AND ('Kawasaki disease') for English studies without any temporal limit. Areas covered: This review aims to comprehensively describe multisystem inflammatory syndromes affecting children during Coronaviruses outbreak, and to evaluate the possible pathogenic role of human Coronaviridae in KD and KD-like syndromes. Expert opinion: An increased incidence of PIMS-TS, during the Covid-19 pandemic has been reported, suggesting that SARS-CoV-2 may trigger a severe hyper-inflammatory syndrome in childhood. The pathophysiological mechanisms of this disease are still unclear. Based on these findings, SARS-CoV-2 may be considered another trigger in the complex mosaic about the relationship among infectious agents and the occurrence of systemic hyper-inflammation related syndromes.

Multisystem Inflammatory Syndrome in Children Related to COVID-19: the First Case in Korea.

Since mid-April 2020, cases of multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease 2019 that mimics Kawasaki disease (KD) have been reported in Europe and North America. However, no cases have been reported in Korea. We describe an 11-year old boy with fever, abdominal pain, and diarrhea who developed hypotension requiring inotropes in intensive care unit. His blood test revealed elevated inflammatory markers, thrombocytopenia, hypoalbuminemia, and coagulopathy. Afterward, he developed signs of KD such as conjunctival injection, strawberry tongue, cracked lip, and coronary artery dilatation, and parenchymal consolidation without respiratory symptoms. Microbiological tests were all negative including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction. However, serum immunoglobulin G against SARS-CoV-2 was positive in repeated tests using enzyme-linked immunosorbent assay and fluorescent immunoassay. He was recovered well after intravenous immunoglobulin administration and discharged without complication on hospital day 13. We report the first Korean child who met all the criteria of MIS-C with features of incomplete KD or KD shock syndrome.

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.

Pediatric Inflammatory Multisystem Syndrome: Time to Collaborate.

There is significant variability in the names and case definition of pediatric inflammatory multisystem syndrome associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Such variability leads to adverse consequences in the quest for further knowledge and management strategies. It is time to collaborate to gain consensus.

The Immunology of Multisystem Inflammatory Syndrome in Children with COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is typically very mild and often asymptomatic in children. A complication is the rare multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19, presenting 4-6 weeks after infection as high fever, organ dysfunction, and strongly elevated markers of inflammation. The pathogenesis is unclear but has overlapping features with Kawasaki disease suggestive of vasculitis and a likely autoimmune etiology. We apply systems-level analyses of blood immune cells, cytokines, and autoantibodies in healthy children, children with Kawasaki disease enrolled prior to COVID-19, children infected with SARS-CoV-2, and children presenting with MIS-C. We find that the inflammatory response in MIS-C differs from the cytokine storm of severe acute COVID-19, shares several features with Kawasaki disease, but also differs from this condition with respect to T cell subsets, interleukin (IL)-17A, and biomarkers associated with arterial damage. Finally, autoantibody profiling suggests multiple autoantibodies that could be involved in the pathogenesis of MIS-C.

False-positive SARS-CoV-2 serology in 3 children with Kawasaki disease.

BACKGROUND: Kawasaki disease (KD) is an acute febrile and eruptive disease with systemic vasculitis predominantly affecting young East Asian children. Recent reports showed that children with KD-like disease from KD low prevalence regions had positive SARS-CoV-2 serology despite a negative SARS-CoV-2 polymerase chain reaction (PCR) in respiratory samples. OBJECTIVES: To describe 3 pediatric Kawasaki Disease patients with false positive SARS-CoV-2 serology. STUDY DESIGN: We retrospectively recruited children with KD diagnosed during the COVID-19 outbreak in Hong Kong. Clinical characteristics and laboratory test results including SARS-CoV-2 PCR results were retrieved. We performed a microparticle-based immunoassay for the detection of IgG against nucleoprotein (NP) and spike protein receptor binding domain (RBD), and a microneutralization assay for the detection of neutralizing antibodies. RESULTS: Three Chinese children with typical KD were identified. They had no epidemiological links with COVID-19 patients and tested negative for SARS-CoV-2 NPA PCR. They were treated with IVIG and aspirin, and were discharged without complications. Subsequently 2 of them were tested positive against anti-RBD and anti-NP antibodies and 1 was tested positive against anti- RBD antibodies. However, microneutralization assay showed that neutralizing antibodies were absent, suggesting a false-positive IgG result. CONCLUSION: Detection of neutralizing antibodies is recommended to confirm previous SARS-CoV-2 infection in IgG-positive but PCR-negative patients.

Multisystem Inflammatory Syndrome in Children (MIS-C) with COVID-19: Insights from simultaneous familial Kawasaki Disease cases.

Recently, an increasing number of SARS-CoV-2 patients with COVID-19 syndrome, which overlaps with Kawasaki Disease (KD), have been reported, supporting the suggestion that infection is one of the triggers of KD. We summarized the reports of simultaneous familial KD cases to better understand the etiopathogenesis of both KD and Multisystem Inflammatory Syndrome in Children (MIS-C) related to COVID-19. Here we discuss the etiology of these syndromes from the point of view of infection and genetic susceptibility.