An immune-molecular hypothesis supporting infectious aetiopathogenesis of Kawasaki disease in children

COVID-19 and cardiovascular consequences: Is the endothelial dysfunction the hardest challenge?

A Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) has become a pandemic disease named Coronavirus Disease-19 (COVID-19) of epochal dimension. The clinical spectrum of COVID-19 is wide, ranging from asymptomatic forms to severe pneumonia, sepsis and multiple organ dysfunction syndromes resulting in poor outcomes. Among the various consequences of severe COVID-19, cardiovascular (CV) collapse appears the most serious and potentially lethal. On the other hand, pre-existent CV comorbidities are also associated with higher mortality. The most reliable hypothetical pathogenetic mechanism for CV complications and cardiac injury in severe COVID-19 patients appears to be a sustained endothelial dysfunction, caused by the interplay of inflammation and coagulation. In this review, we survey papers addressing issues related to severe COVID-19, characterized by enhanced lung microvascular loss, hypercytokinemia, hypoxemia and thrombosis. We discuss about how the virus-induced downregulation of the angiotensin converting enzyme-2 (ACE2) receptor, used to enter the host cell, could affect the renin-angiotensin system, attempting to clarify the doubts about the use of ACE inhibitors and Angiotensin-II receptor blockers in COVID-19 patients. Finally, we point out how the delicate and physiological homeostatic function of the endothelium, which turns into a disastrous battlefield of the complex interaction between "cytokine and coagulative storms", can be irreparably compromised and result in systemic inflammatory complications.

Coronary Artery Dilation in Children with Febrile Exanthematous Illness without Criteria for Kawasaki Disease

Background

Coronary dilatation is the most important complication of Kawasaki disease (KD) and, in addition to some clinical characteristics, is common to KD and febrile exanthematous illnesses (FEIs).

Objective

To assess whether children with FEI, who do not meet the criteria for KD, have changes in coronary arteries dimensions.

Methods

Echocardiography was performed within the first two weeks of the disease in patients < 10 years with fever and exanthema without other KD criteria. To make a comparison with KD patients, we reviewed the echocardiograms and medical records of patients with a diagnosis of KD of the last five years. Coronary ectasia was assessed using Z scores of coronary arteries. The means of the dimensions of the coronary arteries were compared with a z test and a level of significance of 0.05 was adopted.

Results

A total of 34 patients were included, 22 (64.7%) with FEI, and 12(35.2%) with a diagnosis of KD. Using the Z scores of coronary artery, a dilation of any of the coronary artery branches was observed in six (27.2%) patients with FEI.

Conclusions

An important percentage of patients with FEI has coronary artery dilation.

HLA-C variants associated with amino acid substitutions in the peptide binding groove influence susceptibility to Kawasaki disease

Kawasaki disease (KD) is a pediatric vasculitis caused by an unknown trigger in genetically susceptible children. The incidence varies widely across genetically diverse populations. Several associations with HLA Class I alleles have been reported in single cohort studies. Using a genetic approach, from the nine single nucleotide variants (SNVs) associated with KD susceptibility in children of European descent, we identified SNVs near the HLA-C (rs6906846) and HLA-B genes (rs2254556) whose association was replicated in a Japanese descent cohort (rs6906846 p = 0.01, rs2254556 p = 0.005). The risk allele (A at rs6906846) was also associated with HLA-C*07:02 and HLA-C*04:01 in both US multi-ethnic and Japanese cohorts and HLA-C*12:02 only in the Japanese cohort. The risk A-allele was associated with eight non-conservative amino acid substitutions (amino acid positions); Asp or Ser (9), Arg (14), Ala (49), Ala (73), Ala (90), Arg (97), Phe or Ser (99), and Phe or Ser (116) in the HLA-C peptide binding groove that binds peptides for presentation to cytotoxic T cells (CTL). This raises the possibility of increased affinity to a "KD peptide" that contributes to the vasculitis of KD in genetically susceptible children.

Aetiological Significance of Infectious Stimuli in Kawasaki Disease

Kawasaki disease (KD) is a pediatric vasculitis syndrome that is often involves coronary artery lesions (e. g., coronary artery aneurysms). Although its causal factors and entire pathogenesis remain elusive, the available evidence indicates that the pathogenesis of KD is closely associated with dysregulation of immune responses to various viruses or microbes. In this short review, we address several essential aspects of the etiology of KD with respect to the immune response to infectious stimuli: 1) the role of viral infections, 2) the role of bacterial infections and the superantigen hypothesis, 3) involvement of innate immune response including pathogens/microbe-associated molecular patterns and complement pathways, and 4) the influence of genetic background on the response to infectious stimuli. Based on the clinical and experimental evidence, we discuss the possibility that a wide range of microbes and viruses could cause KD through common and distinct immune processes.

Serum exosomal miR-328, miR-575, miR-134 and miR-671-5p as potential biomarkers for the diagnosis of Kawasaki disease and the prediction of therapeutic outcomes of intravenous immunoglobulin therapy

The present study was conducted to screen serum exosomal microRNAs (miRNAs) for the early diagnosis of Kawasaki disease (KD) and to investigate their underlying mechanisms by analyzing microarray data under accession numbers GSE60965 [exosomal miRNA, including three pooled serum samples from 5 healthy children, 5 patients with KD and 5 patients with KD following intravenous immunoglobulin (IVIG) therapy] and GSE73577 (mRNA, including peripheral blood mononuclear cell samples from 19 patients with KD prior to and following IVIG treatment) from the Gene Expression Omnibus database. Differentially expressed miRNAs (DE-miRNAs) and genes (DEGs) were identified using the Linear Models for Microarray data method, and the mRNA targets of DE-miRNAs were predicted using the miRWalk 2.0 database. The functions of the target genes were analyzed using the Database for Annotation, Visualization and Integrated Discovery (DAVID). As a result, 65 DE-miRNAs were identified with different expression patterns between the healthy children and patients with KD and between patients with KD and patients with KD following IVIG therapy. The target genes of 15 common DE-miRNAs were predicted. Following overlapping the target genes of DE-miRNAs with 355 DEGs, 28 common genes were identified and further screened to construct a network containing 30 miRNA-mRNA regulatory associations. Of these associations, only miR-328-spectrin α, erythrocytic 1, miR-575-cyclic AMP-responsive element-binding protein 5/b-1,4-galactosyltransferase 5/WD repeat and FYVE domain-containing 3/cystatin-A/C-X-C motif chemokine receptor 1/protein phosphatase 1 regulatory subunit 3B, miR-134-acyl-CoA synthetase long chain family member 1/C-type lectin domain family 1 member A and miR-671-5p-tripartite motif containing 25/leucine rich repeat kinase 2/kinesin family member 1B/leucine rich repeat neuronal 1 were involved in the negative regulation of gene expression. Functional analysis indicated that the identified target genes may be associated with inflammation. Accordingly, serum exosomal miR-328, miR-575, miR-134 and miR-671-5p may act as potential biomarkers for the diagnosis of KD and the prediction of outcomes of the IVIG therapy by influencing the expression of inflammatory genes.